Types of Printed Circuit Boards

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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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