Homemade PCBs Types
Generally, there exist two methods of manufacturing PCBs at home:
- The ultraviolet rays method.
- 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:
- UV pre- sensitized Copper Clad Boards
- Brother HL-2070N Laser printer
- 200 UV LEDs
- 200 Resistors of 470 ohms.
- Chest/box to house
- Transparent plastic picture frame
- Photoresist Developer
- Muriatic Acid
- Baking Soda
- Hydrogen Peroxide
- 26 and 16 gauge wire
- Wire stripper
- Power Supply
- Buckets for chemicals
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:
- Cello tape
- Acid bowl or Acid Chamber
- Hand Gloves or Safety Gloves
- The printed layout on A4 Glossy Photo Paper
- 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.