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Research has shown that out-of-control heat causes over half of all electronic system failures. Assuming that we can carry out good heat management, we can drastically drive down the number of electronic system failures.

As electronic gadgets keep on being scaled down, the heat demands in these frameworks increment as more features are pressed into more modest gadgets. This is particularly obvious in printed circuit boards (PCBs) that work at high current-carrying capacities. High output power systems, for example, Li+ ion cells utilized in electric vehicles, require an integrated power management system that is based on PCBs. Designers and producers should carry out innovative methodologies to oversee heat produced in a high current PCB design.

Thermal resistance is the distinction in temperature between two shut surfaces partitioned by the absolute heat flow between the surfaces. The level of heat resistance regularly relies upon PCB configuration factors. Utilizing surface mount parts affects positively by reducing thermal resistance. area and thickness of the copper foil on the PCB and the thickness and material utilized for the PCB have a more noteworthy impact. Essentially, more extensive and thicker materials disseminate more heat. However, constraints exist due to the standard utilization of materials and due to item details.

Printed circuit board thermal management techniques to reduce overheating

For effective thermal performance, PCB designers ought to consider the following heat management techniques;

1. Marking thermal hot spots and high-current traces

• To manufacture a thermally steady PCB, thermal impacts should be contemplated during the planning stage itself. The initial phase in the thermal plan is to distinguish the areas of interest.
• Heat modeling and simulation strategies are utilized to track down areas of interest. Additionally, current flow examination should be done alongside it, since high-current follows cause generation of heat.

• The legitimate statistical course of action of parts and high-current follows empowers even dissemination of heat. High-current follows should be steered away from thermally touchy parts, for example, sensors and Op-amps.

2. The thickness of copper and width of traces

Consideration of width of traces for proficient PCB thermal management.

• The thickness and width of the copper pads or traces assume a critical part of the PCB heat management plan.
• Copper traces thickness ought to be satisfactory to give a low impedance path for current going through it.
• This is on the grounds that the opposition of copper traces and vias represent huge power loss and thermal generation especially when they carry high current density. Along these lines, adequate trace width and thickness are prescribed to diminish thermal generation.

 

3. Pad design for printed circuit board (PCB) thermal management.

• Very much like trace thickness, pad thickness is additionally significant. Heat is disseminated straightforwardly towards the top copper layer. In this way, the top copper pad should have adequate thickness and surface area to give sufficient heat dispersion.

• Assuming that the PCB configuration has heat sinks in it, they are normally mounted on the base copper pad. Then, at that point, the base copper pad ought to have adequate inclusion to permit the ideal thermal transfer to the heatsink.
• The parts pin are bound to the PCB upheld by pads. The part is joined with the pad which brings about exceptionally low thermal resistance from the PCB. An exceptional welding pad, that is thermal pad is utilized on the circuit board. This pad is just associated with slender bridges to the copper-encompassing pour.
• The patch glue used to join the part footprint with the thermal pad ought to be negligible.
• An excessive amount of solder paste under the thermal pad can bring about the drifting of parts on a pool of liquid bind during reflow. At the point when this occurs, the part bundle will move. The answer to the drifting package issue is to improve the patch glue or solder paste volume.

4. The setting of high-power components in PCB

• For better thermal dispersal, high-power parts, for example, processors and microcontrollers ought to be put at the focal point of the PCB. Assuming that a powerful part is mounted close to the edge of the board, it will amass heat at the edge and raise the temperature. In any case, on the off chance that the gadget is put at the focal point of the board, heat will disperse over the surface in every direction. Hence the surface temperature of the PCB would be lower and disperses without any problem.

• Likewise, ensure you have put high-power parts from delicate gadgets and keep an appropriate distance between 2 high-power gadgets. Attempt to put high-power parts uniformly across the PCB.

5. PCB thermal vias layout

• Thermal vias are heat-directing copper barrels that run between the top and lower parts of the board. Such vias are great heat conductors that move heat away from basic electronic parts. These vias are ordinarily used to work with fast heat dissemination away from surface mount gadgets (SMD).

• Assume there is no space for a cooling framework on top of the PCB, as on account of a coordinated sensor, indicator, or a loaded board with various parts. The most straightforward method for scattering heat would be through thermal vias to the cooling system (heat sink/ heat pipes).
• The number of warm vias under BGAs or processors ought not to be set in stone by the designers considering the heat dispersal reach and surface area. Standard thermal via parameters are as referenced below:
• The distance across is 12 mil (0.3 mm) put on 25 mils (0.64 mm) lattice spacing.
• Standard copper plating thickness is 1 mil (25 μm) with no via fills.

6. Heat sink

• The heat sink is a cooling technique that moves dispersed heat from PCB parts into a cooling medium. Heat sink deals with the principle of conduction which expresses that heat moves from an area of high thermal resistance to an area of low thermal resistance.

• The heat additionally moves from high-temperature regions to low-temperature regions and how much heat flow is straightforwardly relative to the temperature contrast. The heat sink draws heat away from the PCB to blades that give a bigger surface region to quicker thermal dispersion.
• PCB designers can pick a reasonable heat sink for their design in light of a few elements. For instance, the thermal resistivity of material utilized, the speed of cooling liquid inside the sink, the warm point of interaction material utilized, the number of blades and the space between blades, and the mounting method utilized.

7. The integration of heat pipe

• Heat pipes are cooling gadgets suggested for higher temperatures applications, for example, in rockets, satellites, and aeronautics. The heat pipes are for the most part accessible in an empty round and hollow shape, yet it very well may be made into any shape advantageously.

• The heat dispersed from different gadgets is moved to the fluid inside the heat pipe and disintegrates the fluid. The vaporized fluid condensate at the condenser end and gets back to the evaporator through the wick structure by capillarity. This cyclic interaction guarantees the disseminated heat away from the PCB.
• PCB designers ought to consider a heat pipe that covers their heat source and ought to have the option to twist according to your plan needs. There is a wide scope of heat pipe working liquids accessible, from cryogens to fluid metals. Working liquid determination relies upon the temperature scope of the circuit and the liquid’s substance similarity with the container and the wick of the heat pipe.

8. Use of thicker printed circuit boards.

• For more modest gadgets, cooling techniques like a heat sink, heat pipes, cooling fans are impossible by any stretch of the imagination. In such cases, the main choice is to build the thermal conductivity of the board and spread the created heat. Thick boards with a similarly bigger surface region can scatter heat rapidly.

• The thermal conductivity of a PCB is resolved in view of the coefficient of thermal expansion (CTE) of the materials utilized and their thickness.

• Designers should concentrate entirely on picking material for each layer in the PCB stackup. At the point when the coefficient of thermal expansion of the different materials utilized in various layers is bungled, (repeated thermal cycling) weakness happens to decrease the thermal conductivity. Copper plating in vias and solder balls are more defenseless against harm under high thermal cycling.

9. Incorporated cooling techniques

• Integrated cooling techniques are utilized to accomplish higher coefficients of thermal conductivity contrasted with customary heatsink and fan arrangements. The idea is to blow a cooling agent through vias straightforwardly to the lower part of the processors or BGAs or any heating parts.

• The number of vias ought to be determined by the PCB designer, depending upon the thermal criteria of the mounted part. A solitary via is viewed as first, more can be added on request which relies upon the speed of the cooling liquid and the surface area of the part.

• There are additionally different sorts of integrated cooling strategies, for instance, the inboard cooling strategy delineated previously. In this technique, a hotness exchanger is fused inside the actual board. Since no outer hotness sink or cold plate is required, the

• PCB gathering steps and the heaviness of the result is decreased. However, these coolers require an exceptionally high warm through-thickness around the cooling channels.

10. The soldering concentration.

• The soldering thickness of component joints ought to be even and surrounding to decrease heat accumulation on the part leads. Additional consideration should be given while fastening close vias. There is an opportunity for the patch to overfill the opening prompting bumps on the lower part of the board and this diminishes the contact area of the heat sink.

• PCB planners have two choices to keep away from the flood of a bind. The first thing is to diminish the breadth of the via underneath to 0.3mm. The more modest the vias, the surface strain of the fluid bind inside the via is better, ready to counter the power of gravity on the solder.

• The subsequent choice is the interaction called tenting. It includes covering the stack of the via with a patch of soldering mask to keep the solder from streaming down to the via.

11. Thermal simulation of printed circuit boards

• A definite thermal simulation serves to exactly track down the temperature of a thermal hotspot in a PCB. Thermal simulation is the color scale guide of temperature in the heating area acquired under various circumstances. The unit of temperature in the simulation is degrees celsius(°C). The color scale maps are acquired by computing the temperatures of thousands of points from the circuit boards.

The reason why you should perform thermal simulation

• To find hot areas of interest to stay away from the gamble of gadget failure.
• Distinguish the conceivable dependability of dielectric material with different CTE values
• Further develops item unwavering quality.
• Warm reproductions can diminish the expense of execution by decreasing designing deferrals, field disappointments, and item emphasis.
• Further developing execution and correspondence between the designing and electrical groups.

12. Bigger PCB housing

• Finally, a bigger PCB housing framework can be utilized for cooling too. Screws used to mount the PCB can fill in as effective heat flow paths to the framework body when the screws are thermally associated with spreader and ground planes.

• The number of screws ought to be increased with the eventual result of unavoidable losses when contrasted with transfer impact and cost.

• Metal PCB hardening plates can give an extra cooling region when joined with the heat spreading plane. For applications where the PCB is encased in a housing or other fenced-in area, a cavity filler material gives an improved thermal execution over an air-filled enclosure.

• Cooling solutions, for example, fans and heat sinks are likewise normal ways of cooling a framework, yet regularly require extra space or design adjustments to upgrade cooling potential.

 

Common PCB cooling systems

1. Fans for PCB cooling

• Most electronic PCBs depend on cooling fans, with sizes ranging from 10-inch blowers to 8 mm miniature fans. A couple of heat plan conditions can limit the choice options. Early framework prototypes can assist with refining fan determination.

• The intricacy of airflow implies that picking the right fan might require experimentation. A best practice is to begin the thermal plan from the start of the hardware prototyping.

• Fans move the air by making a pressure differential. If the air is hindered, pressure develops, and no air moves. Assuming the fan is out in the open, there is no pressure across the fan, and the airflow is amplified. The working point is somewhere close to these limits.

• One huge limitation of using fans as a method of PCB cooling is that some fans produce a lot of irritating noise during operation.

2. Heat sink

• A heat sink and fan (HSF) is a functioning chilling solution used to cool PCB. As the name proposes, it is made out of a passive cooling unit and a fan.

• There are 2 types of heatsink namely; active and passive.

1. Active heat sink

• Active heat sinks use the PCBs power supply and may incorporate a fan. Now and then these kinds of heat sinks are alluded to as (HSF), heat sink, and fan. There are additionally fluid cooling frameworks, which have become famous lately.

2. Passive heat sink

• This type of heat sink is one that has no mechanical parts. Subsequently, they are 100 percent solid. They are made of an aluminum finned radiator that scatters heat through convection. For passive heat sinks to work to their full limit, there should be a consistent wind current getting across the fins.

3. Liquid cooling system

• A fluid cooling system is a method used to keep a PCB processor’s temperature low involving water as the cooling medium. This cooling system gives effective cooling and assists with limiting the clamor produced by higher processor speeds.

Types of liquid-cooled systems

1. Integrated cooling systems

• This cooling system, similar to its name, comes included as a component of a PCB housing.

• As all of the fluid cooling gear is gathered inside the housing, presumably this is the least demanding choice to work with.
• This is because it will normally give you the most room accessible inside the housing without having any outside parts to manage.

2. Internal cooling systems

• This cooling system has the water-cooling parts set inside the PCB housing.
• This is because most PCB housings are not planned with this sort of system ordinarily, things may be somewhat clogged. As a benefit, this establishment permits you to keep your beloved case and to move the completed item around with less difficulty.

3. External cooling systems

• In this system, the radiator, supply, and pump are assembled remotely in a different unit.

• As a functioning technique, the fluid coolant is siphoned into the PCB case, and in a return section, a return line pumps the hot coolant that was sent cold out of the case and into the supply.

• The benefit of the external cooling system is that it bears the cost of the inside working space of a coordinated framework as well as can adjust to use with any ordinary case.

• It takes into account a huge radiator and has more cooling power than some other incorporated solutions.
• The drawback is that an exterior cooling framework isn’t quite as versatile as integrated or interior frameworks.

Step by step instructions to Identify Thermal Problems with Your PCB

Designers can utilize a wide scope of procedures to distinguish possible issues. Well-known approaches incorporate the utilization of thermal analysis instruments, visual assessments, and infrared cameras.

1. Direct Thermal Analysis

• Playing out a warm investigation lays out how the parts and PCB will act at various temperatures and conditions. The investigation furnishes creators with a thought of the hotness age and moves inside the circuit.

• Architects can then utilize the analyzed results and reenactments to concoct strategies that will assist them with better heat management.

2. Visually Inspecting the Circuit Board without Power

• The visual investigation is a simple method for tracking down indications of overheating, by looking at burned or partially damaged parts, dry joints, arcing, and so on.

• A portion of the apparent signs incorporates protruding parts, burnt parts, and stained spots on the PCB. Notwithstanding the visual investigation, a smell from the board can likewise highlight heating issues.

3. Utilize Infrared Cameras

• Test specialists can utilize IR cameras to assess powered prototype boards for thermal issues and distinguish issues imperceptible to the naked eye. As well as showing regions where there is an overabundance of heat, the cameras can once in a while distinguish fake or damaged parts whose heat signature contrast from those of genuine parts.

• Thermal imaging cameras can likewise distinguish where the tracks have a lacking solder, hence more heat dispersal.

CONCLUSION

PCB thermal management procedures rely upon various elements including how much heat the parts and circuit disperse, the climate, the general plan, and the enclosure. Assuming the heat generated is low, the circuit can work without extra cooling. However, if the circuit creates higher measures of heat, there should be a cooling instrument to remove the heat.

To give thermally optimized PCBs, producers ought to consider all that impacts temperature right from the concept stage and all through the plan and assembling stages.

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The printed circuit boards form the main skeleton of most electronic devices. These are devices that have triggered major advancements in the area of electronics especially computational devices such as calculators, smartphones, computers, and other appliances. For clarity, a PCB routes electrical signals through electrical components to satisfy the required need or task. In simple words, the PCB directs electricity where to go hence ensuring that the electronics are brought to life.

To achieve these tasks, PCB has copper traces that form the substrate where the electrical signals flow from component to component. These copper routes will always determine the purpose of each PCB.

Before starting the process of printed circuit board design, the designers are advised to visit the nearest fab houses and explain the intended purpose of their designs face to face and also lay down their PCB manufacturing conditions and demands. This is very helpful as it will save the designers from making any errors that can originate from the design stage.

We are presenting this article in order for every designer to be conversant with the step-by-step PCB manufacturing process. Hopefully, most designers will come across this in order to understand how the design process is done and avoid most errors that may be witnessed during the process.

Steps for PCB manufacturing

1. The design and the output.

Printed circuit boards must be compatible with designs that have been created using the design tools. The most used PCB design tools include; Kicad, Proteus, EasyCAD, Orcad, and many others. Before beginning the design, the designer should contact the manufacturer to inquire about their favorite design tools so that to avoid making mistakes in the process.

• After doing the design and it is approved for manufacturing, the designer will generate manufacturing files as per the designers’ specifications.
• The most used file is the GERBER extension file which is also known as the IX274X

• GERBER files carry around very important information like the copper tracking layers, the components notations, apertures, drill drawing, and many others.
• At this point, all the design requirements are fine-tuned to ensure that they have been met.
• After a close examination, the board is forwarded to the fab house for manufacturing.
• To ensure that the design is fit for manufacturing, all the PCB fab houses run the Design For Manufacture (DFM) check before taking the circuit through the manufacturing process.

2. From file to Film

The PCB manufacturing will begin once the designer has generated the manufacturing files and the manufacturer has performed the DFM check.

• The fab houses have a special type of printer called the plotter which is used for making the photo films of the printed circuit boards. These prints will be used to image the printed circuit boards.
• Plotters, although they are laserjet printers, they are not standard laserjet printers.
• They use highly precise technology to provide a detailed outcome of the PCB to be manufactured.

• At the end of the printing, we must be able to come up with the result of a photo in black ink.
• For the printed photo, the black ink represents the conductive copper traces and the other remaining clear part represents the non-conductive layers of the oriented circuit board.
• The outer layer is different, clear represents the conductive copper layer and the clear indicates the parts that are to be etched away.
• The plotter is used to generate this perfect film and the film is stored in a safe place to prevent contamination.

3. The inner layer printing: Where does the copper layers go?

The creation of the film in the above step is for mapping of the copper paths. In this step, we shall be print the figure of the film on the copper foil.

• Here we are preparing to start making the actual PCB. Remember that the simplest form of PCB is made up of laminate board which has epoxy resin as the core material and the glass fiber which also is referred to as the substrate material.
• The laminate is the receiving body of the copper that forms the substrate material.
• The copper laminate material is first cleaned then passed through the decontaminate substance. During this stage, it is very important to ensure that no dust material settles on the substrate. The cleanliness of the PCB is very vital.
• The availability of the dirt on the PCB might cause the circuit to have a short or open circuit.

• Next, the cleaned substrate layer receives a photoresist which is a photo-sensitive layer that comprises a photoreactive layer that hardens moments it is exposed to UV rays.
• The film is fitted into pins that hold them, into the laminate panel.
• The film and the board are passed through a blast of ultraviolet rays. Light will pass through the clear parts of the film and harden the photoresist substance that is under it and on the copper.
• The black ink that was printed by the plotter will always prevent the protected areas from hardening since these areas are slated for removal.
• Then the board is washed with an alkaline substance to remove the photoresist material that was not hardened.
• Then it is passed through pressure wash to remove anything that had not been washed by the alkaline and passed through the drier.
• A technician examines the board physically to ensure that there is no error incurred during the process. He also ensures that all the resists present represents the copper that will remain during the final stage of the process.
• This process is only suitable for boards with two or fewer layers. For multilayer PCB more steps are needed in the process.

4. Unwanted copper removal process.

During the process, there is a need to remove the unwanted copper material. This can be done by the use of a stronger material. here we shall be using the copper solvent solution to achieve our goal. As we do this, the wanted copper parts remain protected by the photoresist material.

• Not all copper materials have a similar process. Some heavy copper PCBs require a lot of solvents to be etched.
• Now that we have etched away from the unwanted copper material, the remaining copper material covered by the hardened resins needs to be cleaned. The hardened photoresistor needs to be washed away.
• We shall end up with a glittering board with only the copper material suitable for the end product.

5. Optical inspection and layer alignment.

After cleaning all the layers, they require alignment punches to ensure that they are well aligned. The registration holes will align the inner layers to the outer ones. The technician will use the optical punch machine to align and punch the layers.

6. Layering up and bonding.

This is the stage where the circuit board takes shape. Al the separate layers are reunited here. With the layer accurate, ready, and confirmed, they only need to be joined together.

• The outer layers are joined with the substrate.
• This process is carried out in two processes that are the layering-up and bonding.
• The outer layer is made up of fiberglass together with epoxy resin.
• A thin copper foil covers the top and the bottom layers of the PCB substrate which contains the copper traces for conduction.

• Bonding is done on a heavy steel table that has metal clamps.
• The prepreg layer is the first one to be placed, then the substrate layer follows the prepreg layer before you finally place the copper sheet. Finally, the sheet of the prepreg sits over the copper layer.
• Then this is prepared by pressing.
• The entire operation is done automatically by bonding press computer.

7. Drilling

Holes are bored into the stack board. All the components that are planned to be fitted on the board are done so using the drilled holes. The drill holes will determine the accuracy of fixing these components.

• The x-ray locator is used to locate where drill holes will be done.
• Before the drilling operation is started, it is advisable you place a board of buffer below the board to ensure that the holes drilled maintain the high level of cleanliness.
• A computer is used to control the drilling machine. The machine will use files received from the designer to locate the exact location of each hole to be drilled.

• After drilling is complete, the entire holes undergo a cleaning process.

8. Plating and deposition of copper.

After drilling, the panel moves to the next stage which involves plating. In this stage, different plates are fused together using the method of chemical deposition.

• After sparkling cleaning of the panel, it undergoes a series of chemical bathing where a thin film of chemical is deposited on the surface of the panel. The copper will go into the holes that had been recently drilled.
• Computers are used to control the whole deposition process so that it can be as accurate as possible.

9. The imaging of the outer layer.

In step three, we imaged the panel with the photoresist. This process is repeated in this stage only that we only image the outer layer of the panel that has the PCB design.

• The process starts with layers in a sterile room to prevent any contaminations on the surface of the PCB.
• Thereafter we apply a layer of the photoresist on the surface of the panel. The prepped surface is then passed through the yellow room.
• The ultraviolet rays affect the surface of the panel.
• The goodness is that the yellow light UV rays do have not enough wavelength to affect the photoresist layer.
• Hold the black ink transparencies together then blast the surface with UV rays to harden the photoresists.
• The surface is then passed through a machine to remove the photoresist that was not hardened due to protection by the black ink.
• Inspect the outer layer to ensure that it is in good condition as expected.

10. Plating

Here we are forced to go back to plating room like we had done in step 8 and do the electroplating of the plate with a thin layer of copper. In the process, the exposed section of the panel from the outer layer section we receive the electroplating of the copper.

• Sometime the process mu involve tin plating so that we can be able to clean up the unremoved copper that remained during the etching process.
• This tin will cover the amount of copper that is not to be etched away and etching will remove only the copper that is not tinned.

11. The final etching

As stated earlier, the tin will protect the wanted copper from etching. The unwanted copper foil and the copper below will be under the etching process.

• The etching will be done using the method of chemical removal.
• After this final etching to remove the copper material, we shall have a clear indication of the contacting and connecting copper paths remaining on the plate.

12. Application of the solder mask.

Before this process, the panel is cleaned nicely and covered with the epoxy solder ink before applying the solder mask on both sides.

• Then the board is passed through a blast of ultraviolet rays which passes through the solder mask photo.
• The covered portion will remain unhardened and will undergo removal to have a complete board.
• Then the board will finally go via an oven to cure the soldering mask.

13. Surface finishing

Sometimes we would like our PCBs to have different abilities and this makes us electroplate our PC Bs with either gold or silver.

• You will find some PCBs with hot air-leveled pads. This is done in this stage and it will always result in the uniform pad.
• PCB manufacturing firms can generate different types of finishing depending on the customer and designers’ needs.

14. Silkscreen.

Almost all finished PCB will receive inkjet writing on its surface which will be used to indicate all the needed information about the PCB.

• Then the PCB lastly passes through the final coating, plating, and the curing stage.

15. Electrical tests.

As the final precaution, the technician must perform electrical tests on the PCB to ensure that it is functioning as expected.

• The automated system is used to do the electrical tests on the PCB and confirm its conformity with the design.

Machines and equipment used in the mounting of components in PCB manufacturing.

PCB drilling machine; even though we have said that the SMD is mounted on the surfaces, remember that there needs to be a connection between layers of the PCB boards. this is done via vias which are very tiny holes drilled on the board. This is done by the use of the drilling machine.

Wave soldering machine; this is used for the soldering process. It is also very important in the mass production of the boards.

The PCB brushing machine; we have talked about via drilling. Now after the drilling process is done, we have debris that is deposited. This debris is removed by the PCB brushing machine.

Pick and place machine; this picks the components, rotates them to the required direction, and places them on the PCB board in preparation for the components solder.
The PCB cleaning machine; does all the necessary cleaning that is required on the board. It also ensures that the board is very dry and free from any form of moisture.

Solder paste printing machine; this is for printing the solder paste to attach the components on the board. It ensures that the process is easy and first.

Reflow oven; this does the actual soldering of the boards.it ensures that the process is done in an effective way. We have three types that are currently common in the market; vapor phase oven, infrared oven, and convection oven.

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In the world of electronics, printed circuit boards have revolutionized the way systems function. They have impacted a lot of things in terms of smartness and efficiency where electronic systems are imaginatively thinking like humans. The printed circuit board area has also experienced significant growth that has led to the development of different types of boards depending on the function intended, the technology used, the needs of the consumers, and the application area of interest. The material used in the designing of the PCBs has also contributed to the raising of different types of these PCBs. Designers and engineers have the task of choosing the appropriate type of PCB to consider depending on the client’s specifications. There are no ready-made PCBs and hence it is the duty of the designers to customize them according to need.

The various types of PCBs available in the market and PCB fab house are:

• Single-layer PCB
• Double-layer PCB
• Multi-layer PCB
• Rigid PCB
• Flexible PCB
• Flex-rigid PCB
• High-Density Interconnect PCB
• LED PCB
• Blank PCB
• Custom PCB
• High-frequency PCB
• Aluminum backed PCB

Let us have a deeper discussion about these types of PCB below.

Single-Layer PCB

This is the most common type of PCB that is available in the market currently. In this type, all components are located on one side of the substrate while the circuit is on the other side. The board has one conductive layer hence acquiring the name single-sided PCB.

• It is the simplest form of the manufactured PCB with only one layer of material of conduction.
• They are best suitable for low-density production.
• The holes where the components are attached are not platted through.

Advantages of single-layered PCB

• It is cost-effective. For instance, if you do not need to waste the extra space that comes in with the double-sided PCBs, then this is the best type you need.
• Suitable for low-density project designs.
• They can be easily manufactured because components can be inserted in the easiest way possible.
• They are very easy to design as compared to other types of PCBs and you have a lower probability of making mistakes in the process. Also, since is made up of a single layer, drilling and soldering can be done very easily.
• They can be repaired easily in case something goes wrong.

Uses of Single-layer PCB

• Used in-home equipment and appliances such as milk vending machines.
• Electronics such as printers, mobile phones, cameras, calculators, and radios.

Double-Layer PCB

From research, this type of PCB is considered the most popular in the industry. They are the getaway to more advanced technologies that exist in the world.

• As the name suggests, they have a thin film of the conducting copper material being spread on both sides of the PCB, that is the bottom and the top side.
• Holes are drilled through the board to allow the connection of the circuit on one side of the board to the circuit on the other side of the board.
• On the double-layered PCB, components are connected by the utilization of two methods namely the through-hole technology and the surface mount technology.

Through-hole technology as the name suggests involves connecting components into the board by inserting their leads in holes and soldering the respective components leads.

For the surface mount technology, the components are placed on the surface of the board and connected by the use of the pads instead of the leads. Sometimes the terminals of these components are made up of many small pins or leads.

• Surface mount technology is the best as it allows the board to save on space hence making a single small board complete more functions as compared to the through-hole technology.

Advantages of the Double-Sided PCBs

• This type of PCB offers increased compactness in circuits.
• It is relatively cost-effective
• It is more flexible to designs hence a more ideal option for the design manufacturers.
• It offers a transitional level of circuit density.
• Reduced cost due to compact board.
• They have reduced sizes as compared to the single-sided PCB.

Uses of the Double-Sided PCBs

• Used medical devices such as scanners and x-rays.
• Mechanical systems such as the high current battery chargers and the engine controllers.
• Find use in the lighting industry because of the advantage of having two insulating layers.
• Automotive and aerospace industry because this type of board can withstand high-frequency vibrations.

Multi-Layer PCB

This is a PCB that contains three or more conductive layers and its through-holes are plated. The multilayer PCB comes with different models.

• If the multilayer PCB is constructed using both rigid and flexible material the PCB is referred to as rigid-flex printed circuit boards. this board can be bent into any given shape.
• In multilayer PCB, the copper conductive layers are bonded together with resin layers.
• This is the most complex type of printed circuit board available in the field of electronics.
• Due to this complexity, you will realize that this type of PCB comes at a relatively high cost.

Application of Multi-Layered PCBs

Medical devices Applications

Electronic devices are very vital in the area of medical diagnosis and evaluation. Like any other area of specialization, the medical field is adapting the technology of miniaturization. With the adoption of non-invasive treatment, many areas in the field of medicine have adapted the miniaturized technology.

• Multilayer PCBs have solved the need for these smaller devices due to their lightweight and small in size shapes.
• Examples of medical equipment using multilayer PCB include x-rays, CT scans, MRI, and blood pressure equipment.

Consumer Electronics Applications

Consumer electronics cover a wide range of electronic equipment that is used at home. This includes the devices that are used for communication such as smartphones and laptops.

• They also include entertainment systems such as music players, TVs, and the kitchen appliances such as microwaves and electric kettles.

Most of the devices listed above are fitted with multilayer circuit boards because such type of PCBs contributes to their better performance and compact designs.

Industrial Electronics

Electronics equipment in an industrial setup is quite different from consumer equipment. This is simply because such electronics are exposed to harsh environmental conditions such as high temperatures, vibrations, noise, and dust.

• Examples of industrial equipment include high-speed assembly lines, spray painting robots, automated assembly lines, and packaging conveyor belts.
• These systems are designed for a long time functioning such as working throughout the day.

In this case, a multilayer PCB is required due to its durability and compatibility.

Computer and Devices

In the modern world. It is almost impossible to imagine life without computers which come in hand with automation. Most parts of these computers from motherboards, the mouse, and the CPU use the multilayer PCB to achieve its relevance. This is because the multilayer PCB has the advantage of space-saving as compared to others. This type of PCB can achieve superior performance when you compare it with other types of PCBs.

Telecommunication Electronics.

• In the area of telecommunication, multilayer PCBs find use in many devices such as satellites and GPS systems which require durability as they still maintain high-performance functionality.
• The development of wireless devices has triggered a high demand for high-speed data transmission and miniature devices which can only be achieved through the use of multilayer PCBs.
• Other applications of these PCBs in the area of telecommunications include; alternators, tower and radar communication, attenuation, amplification, and many others.

Aerospace, military, and defense.

Similar to the area of telecommunication, military and aerospace areas require high-performing and miniature PCBs and this can only be offered by the utilization of the multilayer type of PCBs. These PCBs offer high-speed which is required in the field of the military.

Rigid PCB

 

This is the earliest and most traditional form of the printed circuit board in the world. This type of PCB remains popular. They are rigid and inflexible and therefore, they cannot be bent or coiled.

• They are made up of layers such as substrate layer, solder mask layer, copper conducting layer, and silkscreen layer which are permanently fixed with adhesive and high temperature.
• Although some of these circuits are single-sided PCB, most of them are either double-sided or multilayered.

Advantages of Rigid PCBs

Compact PCBs

One of the very significant things about rigid PCBs is that they are small in size. The compact size of the PCB ensures that various complex circuits can be created.

• It takes up limited space in its area of application.
• Due to the reduction in the size of the PCBs and their components, this type of PCB provides a basis where this can be achieved.

Low Electronic Noise

The design of this PCB ensures that we have very minimal electronic noise. This can be achieved by ensuring that the assembled electrical circuit components have minimal current flowing between them.

The effect of this is low radiation effects from the PCB.

The low radiation current and electric flow mean that the PCB is not able to pick many electromagnet waves hence reducing cross-talking between electronic components.

Ease in repair and diagnosis.

These types of PCBs are easy to repair and also diagnose in case of any mechanical challenge.

• All the components in this PCB are marked hence making it easy to locate any component hence making the process of assembly and disassembly very easy.
• Also, the traces of this type of PCB are well marked and visible making it easy for the technician to follow them during the repair.

Immunity to movement

The components are fixed to the board using the solder and the flux. The process is done such that the components remain fixed on the board and they cannot move even if the PCB is used in areas with has conditions such as high temperatures and mechanical vibrations. This makes such PCBs suitable for applications that involve shaking and frequent movement.

Flexible PCB

• Unlike the rigid PCBs that are made up of rigid materials like fiberglass, flexible PCBs are made up of flexible materials that can be bent or flex and move such as flexible polymers.
• They come either single, double, or multilayered types.
• Since they are printed on flexible material, then this type of PCBs will cost relatively higher as compared to others.

Features of flexible PCBs and Rigid PCB

Advantages of flexible PCBs

• This can be freely bent, wound, and also folded. This allows it to be moved in any space whether tight, small, or shapeless.
• They can greatly reduce the weight and the size of the printed circuit boards.
• They have the benefit of good solderability and good heat dissipation.

Flex-Rigid PCB

This is a combination of both the rigid PCBs and the flex PCBs. It is made up of a multilayered printed circuit board that is combined with some layers of rigid PCBs.

Advantages of flex-rigid PCBs

1. Increased reliability.
2. Space-saving
3. Reduced cost
4. Ease of testing

High-Density Interconnect PCB

PCBs are made up of components that are interconnected and fixed on them. The components are connected by wiring them on the board. The wiring is in form of tracks and traces. Some boards involve a small low density of wiring capacity per unit area while others involve very high-density wiring capacity per unit area. HID which is an abbreviation of the high density connect boards are boards that have a high density of the wiring capacity per the unit area when you compare with the normal PCBs.

• These boards are very special as they come with finer lines, tiny vias and a high connection density of the pads than the one that is utilized in the normal boards.
• A good HID PCB should have one or all of the following:

1. Blind and buried vias
2. Micro vias
3. Build-up lamination
4. Considerations of high signal performance.

• The HID boards are very compact with small vias, micro-vias, spaces, pads, and copper traces.

Benefits of the HBI printed circuit boards.

This technology has found great importance in smartphone and tablet manufacturing. Apart from that, they have become of great use in laptops and desktop computers. The following id the great benefits of the HDI PCBs;

1. Tighter designs; when we have a look at the high density interconnect PCB, we will realize that the board has a very high-intensity nature of circuit network connection. This high intensity implies that the board takes literally less physical space. The utilization of design features such as blind and buried vias enables the designers to come up with more compact builds and this will make the HDI circuits very versatile.
2. Reliability; the connectivity that is employed in the design of the HDI boards such as the use of the blind vias and the buried vias makes them more physically reliable. This is because such types of connections are less likely to get compromised.
3. Lighter material; the material used is very light and cooler. The traditional and other PCBs use a different variety of materials but the common one is the combination of copper, aluminum, fiberglass, and other metals which might prove to be bulk. This is not the case with the HDI boards.
4. Sharper signals; since these types of PCB has more compact systems, then the outcome is that the signals will have a very short distance to travel hence avoiding many disturbances that come in with the long-distance travel. This advantage makes the signal rich their destination undisturbed hence sharper performance of the board.
5. Pocket friendly; four layers of the HDI boards are enough to perform all the functions of the standard PCB layer. The board has reduced size, which implies a reduction in the cost too.
6. Low power consumption; these types of boards have a high number of transistors and also signals travel a very short distance. These features play a greater role in reduced power consumption in these types of boards.

The common use of the HDI boards.

These types of boards have found many areas of use in the modern world of technology. Let us have a look at a few areas where the high-density interconnect boards are used;

Healthcare

Due to the smaller size of the HDI boars, medical designers have found great interest in this type of board. The medical equipment is compatible with HDI because they are very small and can fit into them for example in implants and also in the imaging equipment. The equipment plays a very significant role in the treatment of the ailments and therefore smaller chips that require less intervention have to be used. Let us take an example of a heart pacemaker that is implanted in the heart to regulate the speed of the heart bit. The pacemaker should be very tiny and therefore the HDI has provided boards that can solve the size of the pacemaker issue. another good example is the colonoscopy which is passed through the colon of a human to carry out the colon examination. It is evident through research that so many people avoid the colonoscopy examination due to the painful experience but the availability of the HDI technology has drastically reduced the size of the camera and improved the visual quality of the same camera which has made the colonoscopy process less painful hence triggering the increased number of people searching for the service.

Aerospace and military.

Military use strategic equipment such as missiles and some other defense communication devices. This equipment utilizes the HDI technology in their boards since it is the only efficient available method. there have been greater changes in aerospace technology and HDI has always provided the needed solution. Communication devices such as wireless phones and trackers are becoming very tiny in size and this is due to the involvement of too many tiny layers of the HDI boards.

Automotive industry.

The car and other automotive manufacturers are falling in love with the HDI boards simply because with this type of board you are assured of greater discoveries and innovations. This board allows the saving of more space in the vehicle and also have increased performance of the same vehicle. To be specific, Tesla uses the HDI technology to run the electric car system where it helps in extending the battery life of the system. Other driver assistants such as cameras, tablets etc fit on the dashboard.

Digital devices.

Let us make a comparison of todays digital devices like the smartphone with what we had 10 years ago and you will make note that there is a very big improvement in size, thickness and weight. This has been made possible by the use of the HDI boards in this area. Thinner and more compatible smartwatches are also a product of the HDI boards.

Advantages of the HBI PCBs

• Compact design; the strategic use of the burred and blind micro vias makes the board compact and this leads to spacing.
• High reliability; the preferred use of the stacked vias makes the board have a super shield against harsh environmental conditions.
• Phenomenal versatility; this board is ideal where weight, size, and performance are of great consideration.
• Cost-effective; the functionality of a 6- layer standard PCB can be reduced to a 4-layer HDI board without altering its intended purpose.
• Better signal integrity; vias and pads and blind technology are what is mostly used in the HDI. It also has very short compact trucks or traces and this reduces the chance of the signals being interfered by the external forces hence achieving of very high signal integrity.

Other types of PCBs include:

• LED PCB
• Blank PCB
• Custom PCB
• High-frequency PCB
• Aluminium backed PCB

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The process of PCB ordering and manufacturing is time-consuming and requires prior planning. This tells us that it is not necessary to order for less volume PCBs through a manufacturer or even order for your own hobby PCB. To make the process economical, we have to understand how to make our own boards from home. This tutorial is about how to make our own PCBs from home to avoid some expenses and also saves time in the end. it is very significant to note that this process cannot be used to build complex circuits and sometimes it is very unreliable. Therefore, the process is important in the building of simple circuits such as the Arduino circuit that we shall be using in this process.

Homemade PCBs Types

Generally, there exist two methods of manufacturing PCBs at home:

1. The ultraviolet rays method.
2. The toner transfer method. (most commonly used)

• These two methods are almost similar with only one or two steps making the difference.

1. The Ultraviolet Rays Method

 

The following steps will show you how to do your own PCB using ultraviolet rays.

The material needed for this method to be accomplished practically are listed below:

PCB Comopnents:

• Transparencies
• UV pre- sensitized Copper Clad Boards
• Brother HL-2070N Laser printer
• 200 UV LEDs
• 200 Resistors of 470 ohms.
• Breadboards
• Chest/box to house
• Transparent plastic picture frame

Chemicals:

• Photoresist Developer
• Muriatic Acid
• Baking Soda
• Acetone
• Hydrogen Peroxide

Tools:

• Soldering
• Screwdriver
• 26 and 16 gauge wire
• Wire stripper
• Gloves
• Goggles
• Power Supply
• Q-Tips
• Buckets for chemicals
• Timer

Step one: Building of the UV LED Box.

 

We started by finding a box that is one foot in height. Then we place the breadboards on the transparent glass paper and do the arrangement of the LEDs as shown in the image above.

Step two: Drawing of the Schematic

The next step involves drawing the schematic for the circuit that you intend to design.

• There is so much free Electronic Automation Design software available in the market and you have to choose the one that you are conversant with. For me, I had to settle for Autodesk Eagle.
• Once the schematic and the layout has been finished, you have to print it on the transparency.
• For you to be able to print only the desired layers, turn on the top layer, the vias, and the pads. This is achieved by selecting the correct setting in the EDA software.
• The end results of the schematic and printing should be similar to what is displayed in the image below:

 

Step three: Exposing the Pre-Sensitized board to UV rays

 

• Place the printed transparency about 10 inches above the LEDs. Let the inked face upwards the sky.
• Ensure that the room is dark then peel off the white film on the pre-sensitized circuit board in order to expose the photoresist.
• Place the printed circuit board on the top of the transparency while the photoresist is facing downwards in the direction of the LEDs.
• Place some weight on top of the printed circuit board to ensure that the photoresist is tightly fitted on the ink of the transparency.
• Turn on the UV ray box for at least one minute.

Step four: The Developer Solution Preparation.

 

• The next step is the preparation of the developer solution where one part developer is mixed with 10 parts of water that are the ¼ cup of the developer is equal to 2 ¼ cups of the tap water.
• Ensure that you mix the developer and water completely so that the photoresistor can be eaten uniformly to get the desired end product.
• Place the PCB on the solution and shake it up nicely to wash away the parts that were exposed to UV rays. This will take at most 10 seconds.
• Do not leave this board on the developer for a long time since by doing so, the developer might wash away all the photoresists.
• Now place the PCB in cold water to stop further reaction once you remove it from the developer.
• Don’t spill of the developer solution for it can be reused for other boards development.

 

Step five: Etching Copper Away.

 

• Here we start by preparation of the solution where one-part muriatic acid is mixed with two parts of hydrogen peroxide. In my project, I made use of 8oz. of muriatic acid against 16oz. of hydrogen peroxide.
• This acid is stronger than the photoresist and therefore, you must be very careful. Ensure you make use of the proper personal protective equipment before making use of the product.
• Put the printed circuit board into the solution and ensure that you shake the bucket very carefully.
• You will notice the solution turning into green color as copper is being etched away.
• As soon as you notice that the whole copper has been etched away, remove the PCB from the solution. The time frame for copper to be etched away is about 2 minutes.
• Use a hose to clean the etched PCB.

 

Step six: Removing of the Photoresist.

• This step makes use of the acetone and Q-tip to remove the photoresist.
• It is very easy to remove the photoresist using Q-tip that has been dipped in acetone.
• Keep using new Q-tips until they remain white to indicate that the whole photoresist has been removed.

 

Step seven: Populate the Printed Circuit Board with Parts

 

 

At this point with you is the PCB to populate with all the parts that are required. Enjoy the process.

The Toner Transfer Method

According to me, this is the simplest method to do your own PCB at home as compared to the ultraviolet method we have discussed above. This method offers advantages such as stability and reliability

• We are going to have a look at how this method is made possible and let us start by listing the material that we require in the process:

 

Materials

• Cello tape
• Acid bowl or Acid Chamber
• Cup
• Hand Gloves or Safety Gloves
• The printed layout on A4 Glossy Photo Paper
• Scissor
• Sandpaper
• Hacksaw
• Permanent Marker pen
• Copper Coated Board
• Steel Wool
• Muriatic Acid
• Hydrogen Peroxide

Step 1: Making your Customized PCB Design

Here we shall be masking the use of the EDA design software to generate our schematic and the layout.

• If you are new to PCB design you can search online for several tutorials on how to do design using EDA software.
• Again, there is too many design software that you can choose from such as fritzing, Kicad, Proteus, EasyCAD, and many more.
• On the EAD you will be able to generate drawing like the one shown below:

Step 2: Printing of the PCB Layout

You must print your PCB design on a good laser printer because we shall be utilizing the toner transfer method to do the transfer of the copper surface by use of the heat and copper coated board as the substrate.

• Check out the image that is attached below:

• Use thin and glossy photo paper for image printing because the normal paper will absorb the color immediately you print.
• Make sure you use the thick black color because there is no other color that works out.
• Check the printer settings attached below:

Step 3: Preparation of the Single-sided Copper Board.

After the designing and the printing has been done, now we look forward to the preparation of the copper board.

• Here the quality of the single-side coated copper board is very important. You should settle for the best quality otherwise you might end up with poor results.

• Clean the copper surface by scrabbing to remove the dust and any other unwanted material and the copper oxide materials which could have been formed through oxidation. You can utilize steel wool or sandpaper in the process of cleaning.
• Make sure you don’t use the sandpaper and the steel wool hardly. Use them gently to get a nice surface.

 

• Generally, you will get the copper board in a full standard size, and hence you have to utilize the hacksaw to cut the required size.

• Now, cut your printed PCB design using the laser printer. Use the razer to cut the part printed and place the printed side on top of the copper board and fix the sides on the board using the tape so that it cannot move during ironing.

Step 4: Transfer the ink to the board by ironing.

• As I had said earlier, this is the toner transfer method. we will employ heating and pressure techniques to transfer the ink from the paper to the copper board. We shall utilize a hot iron to do so.
• Use simple and gentle ironing on the backside of the copper so that the heat can be transferred easily.
• Iron for like 15 minutes and you will see the copper turning blackish after ironing for like 10 minutes. This will be the indication that toner has been passed well.

Step 5: Paper Removal from the Board

• Drop the board in hot water for about 15minutes to allow it to soak. After 15 minutes the paper will have softened.
• Now, rub it with your fingers and remove it gently then peel off the layers one by one.
• After the first layer peeling off, then drop it in the water and repeat the procedure to peel of the second layer.
• Repeat the procedure until you peel off all the paper layers from the board.

• When you have removed all the paper layers, the copper surface gets dry but we still have a paper layer sticking on the surface of the board which cannot n]be removed by hands.
• Take a toothbrush and gently brush it off as shown below. You will realize that with brushing the thin copper paper gets off.

Step 6: Acid Solution Preparation for Etching of the Copper Layer.

• This step involves the making of an acid solution that can be used in the etching of the printed copper-coated board.
• Ferric chloride is normally used in the making of the acid. But, in our process, we shall be using another method because ferric acid is not easily found and if the ferric acid is available the purchase procedure is very tiring due to the documentation that is required.
• Therefore, I shall be using muriatic acid which is readily available. I mixed 3 cups of muriatic acid with 1 cup of hydrogen peroxide in a bowl to make a solution that is green in color.

Step 7: PCB Etching

• Now that the acid solution is ready, just drop the PCB in the solution and leave it for 15 minutes to etch.
• For complete etching ensure that after every interval of 2 to 3 minutes you steer the solution.
• After complete etching, you need to rinse the final product with clean water to stop further etching.
• After the board has dried, take a piece of cotton and drop it on acetone solution and cleanse the board until all the greenish color have been removed.

Step 8: Drill holes for Mounting your Components

After all the above procedures, we have to end up fitting the components on the board. To do this, we should be available to drill holes on the PCB.

• Holes can be drilled using a drill either homemade or commercially available PCB drilling drills.
• For me I used my own homemade drill shown below:

Advantages of Doing the PCB by yourself

• The process saves time that could be have been consumed while doing the booking of the manufacturing process. The PCB can be manufactured quickly and a complete PCB be obtained within the shortest time possible.
• It is cheaper for low volume production of PCBs.
• It is the best method that is recommended for low-volume prototyping.

 

The Disadvantages of doing PCB by Yourself at Home.

• Mass production cannot be achieved by the use of this manufacturing process.
• The manufacturing process is cumbersome to the user of the process.
• If high efficiency and accuracy are required, this method cannot be utilized because it has very low efficiency.
• High quality cannot be guaranteed while using this method.
• Finding the material for this process is not for average people.
• Finally, if the design is so complex, you cannot find the solution for this board and therefore you will be forced to look for a manufacturer to help you out.

 

PCB Designing Process for Mass Production

After having a look at the homemade PCB process, here am going to give you a precise way of doing PCB manufacturing for mass production. It will be a step-by-step guide that will be understandable for anybody who has the ambition of understanding this process.

Step 1: Schematic Design

The schematic design also known as the schematic diagram is the blueprint for any PCB design process.

• It is a representation of the logical component connections, the traces, and the circuitry that is required in the process of the PCB design.
• Every component that is to be used in the design has a symbol that is placed on the board to represent the component.
• It is the work of the client to come up with the idea of what should go into the PCB as the designer will build the schematic depending on the idea.
• Each symbol used has one or more pins that are connected by lines to form nets.
• The schematic is made using the EDA software as discussed in the homemade PCB design.

Step 2: PCB layout planning.

Once all the symbols have been laid on the circuitry to form the schematic, the board is taken through the next stage called PCB layout which involves the following procedure:

• Creation of all the models of the physical components within the tools.
• Make sure that the nets don’t come in contact with each other hence avoiding sort circuits once the PCB is built.
• Setting up the physical appearance of the PCB. The shape and the color will be preferred.

Step 3: Placement of Components Planning.

Once the design of the schematic is ready, the next process involves the placement of the components planning. This process is very helpful in determining how many PCB layers you will require and many other specifications in your design. These steps will also ensure that you avoid errors in the process of design hence saving time and drastically reducing the cost of your PCB manufacturing.

The footprints are placed in the following order:

• Fixed components like the switches and the connectors are the first to be placed in the layout datasheet.
• Second to be placed are the critical components like the microelectronics and the power supply systems placed next to the fixed components.
• The PCB supporting components such as the capacitors and the resistors are placed around the critical components.
• Finally, the PCB supporting elements such as the decoupling capacitors and resistors are placed.

Step 4: Connecting Routing

After the PCB components have been laid, it is time for connecting these components with traces. This process is referred to as PCB routing.

The four most common trace routing methods are:

• Manual routing – the designer does the routing manually by drawing a single trace at a time
• Semi-automated routing– there is a semi-automated feature in the design tool which a design uses to draw a single or many nets of the traces.
• Auto-interactive routing– here it is a combination of the manual and the semi-automated process.
• Batch auto-routing-the designer will do the routes manually and set several design rules to guide the process.

Step 5: Designing the 3D

This comes in after the PCB routing.

The designer will deliberate on the size of the PCB that is required and generate the exact size.

At this point, all manufacturing files are generated and delivered to the manufacturer for the process of manufacturing to be initiated.

In the next article, we shall have a look at the PCB manufacturing process and how we can order for PCB manufacturing in an online platform.

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All over the world, we are surrounded by electronic devices. Whether we are working in offices or at homes, it is very easy to come across an electronic device. Some of them we walk with such smartphones, tablets, and laptops. Some are amazingly beautiful while others are subtle. All these devices have a board inside them that is referred to as a printed circuit board (PCB).

The printed circuit boards have been available since 1945 when they were discovered for military use during World War 2. When they were made commercially available, many manufacturers adopted them as the most suitable method for assembling electronics as compared to the traditional available point-to-point connection of the electronic circuits.

Over the years, the area of the printed circuit board has seen immense growth and also witnessed the introduction of new technologies in circuitry generation to meet the market demand and also to accommodate the new trends in the area of electronics. The knowledge about the electronic design and printed circuit boards can fill a shelve and today we are going to have a look at the basic introduction of it.

Definition of Printed Circuit Board.

A printed circuit board is an electronic rigid structure that is made of embedded metal wires referred to as traces/tracks and some large areas of metals referred to as planes. The electronic components are then fixed on the top, bottom, or even on both sides of the board using the metal pads. They can also be fixed on the sides of the board. The metal parts are also fixed on the boards to allow the components to be interconnected together. The board can be made up of a single layer of circuitry with components connected on either side or both or even can be made up of multiple layers of the circuitry that are stacked together.

• The board plane is made up of a dielectric material that is free from electrical conductivity so that it can be free from contaminating the electrical signals.
• The FR-4 is the standard material that is used in the production of the PCBs while the metal planes and the traces are made up of copper material.
• The printed circuit boards find great applications in many fields of electronics. You can find complex boards on computers and telecommunications and simple boards in child toys.
• Some boards are made up of specialized materials due to the high frictions and frequencies that they operate with such as high temperatures while others are made up of flexible materials so that they can be bent or even fitted in their areas of use. Also, some of the boards have heavy copper traces dues to their applications. In the current market, you will come across boards that have been built for extreme environments such as sensors that operate under high temperatures for example in car engines and boilers.

Although these are some of the noticed applications of the printed circuit boards, they all follow a similar construction process. Let us have a look at it below:

 

The PCB Making Process.

To come up with a physical printed circuit board, you must start by designing it. The design process starts with Electronic Design Automation which is made successful by the use of the design tool.

• The design process is divided into two stages

1. The schematic which involves the creation of the circuit connectivity in a diagram
2. The PCB layout involves the creation of the physical circuit board.

• Step number one involves the creation of the libraries that you need to use in your design. These libraries comprise the symbols, the footprints, and the 3D model of the components that you want to use.
• Once all the models are ready, the next things involve the creation of the schematic logical diagram. The CAD tools are used to place the symbols in the working space and interconnect them to form circuitry.

 

• At the same time, we have to simulate the circuit to ensure that it is functioning as it is intended. Once this is done, the simulated circuitry connection is passed to the next stage which is the PCB layout stage.
• At the layout stage, the schematic is received as nets that connect two or more components. With the outline of the PCB desired shape, the designer will place every component on their desired space.

 

• Once the components have been laid optimally, the next step is to connect the pins using the traces. The design tool will have several in-build rules and restrictions that stop the traces from crossing and touching each net and also control the size of the width governing each trace. Once the routing is completed, we shall have to use the design tool to generate all the documents required for the manufacturing process to be accomplished.

 

It is very clear that the design and manufacturing of the printed circuit board is a step-by-step process that starts with the design and simulation of the schematic, then the layout process where routing of the board is done, and also the generation of the relevant manufacturing files before delivering the final design to the manufacturer. The relevant manufacturing files that should be generated from the design tool include the pick and place files, the bill of material files, the GERBER files, and the drill files. The final step in the building of the PCB will involve assembling the BOM and building the final board. Let us have an in deep looking into these steps.

Important Files in the PCB Design and Manufacturing Process

During the process of the design of the PCB, before proceeding to order the PCB through the manufacturers’ site, there are different types of files that you need to generate using the Design Tool. Let us discuss them below:

GERBER files

They are the most common and also the most used files in the area of electronic design. They can be produced by almost all the EDA tools. In manufacturing, they are referred to as stencil data or light painting files.

The GERBER file is in two different types: RS274-X and RS274-D.

The GERBER file is a very crucial requirement in the design process, and if the file has inconsistent then the design will not be that good.

BOM files

BOM also known as a bill of the material file shows the list of components that are needed to make the PCB and does the matching of the components to the correct designator in the PCB layout. It also has a column for the source of the part, part number, and the manufacturer of the part. The file is in excel form as shown below.

Pick and Place Files

This is simply the list of all the components in the design and their respective coordinates and the rotation. Most EDA tools can generate the components’ x-y coordinates and how they have been rotated. They are always in excel form as shown below.

 

Types of Printed Circuit Boards

The printed circuit boards are classified into many different types depending of the number of layers that are available in the board and also the manufacturing process that was used. They are classified as follows:

Single-Sided PCBs

This is the most common PCB with a single copper layer above its substrate.

• The electrical components are placed on one side of this board. The conducting paths cannot intersect since it utilizes a single layer hence a lot of space is needed.

Double-Sided PCBs

A thin layer of conducting copper layer is added on both sides of the boards and holes drilled through the board allow the metal parts to be connected across both layers.

• These types connect the parts from one side to the other using one or two methods; ie THT or SMT.

Multilayer PCBs

This has more than two copper layers. Generally, a board featuring at least three layers will fall under this category.

What You Need to Know before Doing a PCB Design.

Many of us would like to become PCB designers. To some, it might be seen as an easy journey, and to others, it might become a complex journey. Here am going to take you through what you need to know before becoming an expert. First, you need to know the many electronic components involved in the design process. Secondly, you should have the know-how of the necessary EDA tools such as KiCAD, Proteus, EasyCAD, and many others which will help you in doing the design before sending the complete design to the manufacturer. Thirdly, we shall have a look at the different, materials that are very necessary for building the board used for the circuitry attachment and finally we shall see the manufacturing process is done especially the mass production. Let us start with the component.

PCB Design Components/ Elements.

PCB design starts with an Electric Circuit. An electric circuit is an interconnection between components of various types and purposes in which there is at least one enclosed path in which an electric current can flow as shown in the image below.

performance of a system be it mechanical or electrical is done by drawing of its electrical circuit equivalent. by simulating this circuit, any system can be studied. This tells us that the performance of any system can be studied by mastering its circuit theory.

Below are the elements that are commonly used in electronic circuits;

Active elements:

are elements of the circuit that have their energy. They are independent of an external power source. They are of two types that is a current source and a voltage source.

Passive elements:

these elements do not possess energy of their own. They depend on an external source of energy. This is the area of focus of this article and therefore more discussion will follow. An example of this is a resistor.

Linear and non-linear Elements:

• Linear elements show the linear characteristic of the voltage and current which is in most cases a straight line. Example a resistor.
• For the non-linear elements, the v-I do not follow a straight line. Example diode

Bilateral and unilateral elements:

Bilateral elements have the same relation existing between voltage and current for current flowing in bi- directions. Example current source.

Unilateral elements do not have the same relationship existing between their voltage and current flow. Example a silicon diode.

Lumped and distributed elements:

Talking about the lumped element, our focus shifts to those very tiny in size elements in which actions take place simultaneously. We can have a few examples such as resistors, inductors, and capacitors.

On distributed elements, we can define them as those elements that are not separatable electrically for analysis. They include for example a transmission line that has distributed parameters along its length and may extend for hundreds of miles.

Now after having a reminder on what electrical elements are, let us go back to the purpose of this article. Our focus is on passive elements and we have already introduced what they are in our introduction.

Passive Electronic Components.

Passive elements are those elements that do not possess energy of their own. They are dependent on an external source of energy such as a current source or a voltage source. These elements do not generate power but they dissipate energy.

Passive elements are part of electronic circuits. 99% of the circuits we have around have either one or more passive elements. Before we get deeper, I would also like you to know that we have different techniques of how to fix components on a PCB board. Yes, two methods;

• Through-hole technique; the PCB board has holes drilled through them where the components with long legs are fitted through and soldered. It was the first method to be used although today it is not in much use.
• Surface mounting techniques; in this technique, the components or elements are laid on the surface of a PCB board then it is interconnected through copper pores. This is the latest technology that has led to the generation of compact and small components hence leading to reduced board sizes.

Having this in mind, it is very important to note that, passive elements also exist as a through-hole device (THD) or as a surface-mount device (SMD).

 

Let us now shift our focus to some passive elements that are commonly in use and are used. This will give us an early signal on things to consider while using passive elements. You cannot use an element without knowing what it is, what it does, and where to use it.

The Material used in the PCB Manufacturing

There are three types of PCBs and all will have different types of material. However, they all have similar primary materials. below, we are going to have a discussion on the different materials used in the manufacturing of the printed circuit boards.

Substrates

This forms the base of any printed circuit board upon which the manufacturer will mount the components and create the circuit to make the board complete.

• The type of the board is depended on the type of material that forms the base.
• Mainly there is the availability of two materials that are commonly used by the manufacturer to form the base of any given PCB namely; the fiberglass substrate and the plastic substrate.
• The fiberglass substrate is best suited for rigid, strong, and flexible PCBs used in the area of medicine.
• The plastic substrate is the cheapest option and also the most flexible option. Therefore, most manufacturers go for the plastic substrate. Plastic substrate durability is dependent on which type of material is used which includes; liquid crystal, polyimide, and polyester.

Conducting Material

Besides the nonconducting substrate, in any given printed circuit board is the conducting material that facilitates the creation of the traces and the completing of the circuit. This is made up of copper material.

• How the copper sheet is laid is defined by the designer depending on the usability of the board.

Solder Mask

This is a protective layer that is used to insulate the copper traces and protects them from damages such as short circuits and environmental dust and moisture.

• Without the soldering mask, oxidation will take place on the solder liquid hence making the circuit stop working.
• Besides the protection function, the solder mask determines the color of the printed circuit board.
• The most common color is green, but manufacturers have come up with solder masks of different colors such as blue, red, etc.

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