PCB etching process

[IlyasOsman]

Are you tired of using a breadboard for your projects? Do you find it exhausting to deal with all the wires, constantly struggling to remember which one goes where on the breadboard? 😕 Well, look no further; you've come to the right place. 😌 This is a straightforward guide to designing and fabricating your own PCB at home, whether for a personal or school project. At the Nakuja project, we specialize in designing PCBs for avionics and flight control systems using design software like EasyEDA. We print the designs, etch the PCBs, and solder the components ourselves.

This blog aims to provide you with a step-by-step guide to the etching process. I hope you enjoy creating your PCB!

Materials Required:

• Board design (created with EasyEDA, Eagle, etc.)
• Clothes iron
• Copper-clad board
• Sandpaper
• Cupric chloride
• Water
• Plastic dish or basin
• PCB drill
• Soldering iron
• Solder wire

Note: The etching solution is CORROSIVE and toxic, so handle it with care, wear proper safety clothing (gloves), and work in a space with proper ventilation.

Hazard Summary:

1. Cupric chloride can irritate the nose, throat, and lungs when breathed in, leading to coughing and wheezing.
2. Direct contact with cupric chloride can cause severe skin and eye irritation, possibly resulting in eye damage.
3. Ingestion of cupric chloride may lead to stomach issues such as salivation, nausea, vomiting, stomach pain, and diarrhea.
4. Prolonged exposure may cause damage to the liver and kidneys.
5. Cupric chloride is classified as a DOT CORROSIVE CHEMICAL.

Step One: Design

1. Design the board (single layer) using various services such as Eagle, Fritzing, or EasyEDA. In this case, we used EasyEDA.

   • Note: To ensure your design is easy to etch and the tracks appear clearly after etching, set some design rules; for example, a track width of 1.5 and clearance of 0.5. Some tracks, such as those supplying 12V, should be thicker than others.

Fig 1. PCB design on EasyEDA

2. Once the design is complete, save your work, then select File, Export, PDF as shown below.

fig 2. Design export step

3. Select the specific boxes as shown in the diagram below.

fig 3. Design export properties

4. Once done, the downloaded PDF should resemble the image shown below.

fig 4. Downloaded PDF of the PCB design

Step Two: Print out the Design onto the Shiny Side of a Glossy Paper

Once you have the PDF as shown above, print out the design on the shiny side of glossy paper. When printing, ensure:

1. The printer is a laser printer, not an ink jet.
2. The print dimensions are actual size, not fit.

Step Three: Cleaning the Copper Clad

It is IMPORTANT to wear gloves from this step onwards to handle the copper-clad and etching solution. This helps in avoiding getting oils on the copper and chemicals, and copper filings on your hands. Clean the copper clad using fine sandpaper. Scrub the surface until it is bright metallic looking. Wash off the surface with running water to remove the small copper filings from the sanding.

Step Four: Toner Transfer

1. Cut out the design leaving some margins around it.
2. Place the cut-out with the glossy side facing down on the copper clad.
3. Place the hot clothes iron on top of the paper and press down for about a minute.
4. Move the clothes iron around the paper for about 3-5 minutes while still applying pressure. Do not lift the paper when hot as this will result in no toner transfer.
5. Place the PCB in water until it cools and remove the paper using your thumb and fingers. Ensure that all the paper is removed, especially in between tracks, as this might result in the area not getting etched.

fig 5. PCB placed in water to cool before removing paper

Step Five: Dissolving the Copper

1. Dissolve a sufficient amount of cupric chloride in water.
2. Submerge the PCB into the solution and agitate until all the copper around the design has dissolved.

fig 6. Removal of copper

Note: In case the process is taking long, you can speed it up by dissolving some more cupric chloride into the solution.

4. Once all the copper is etched, remove the PCB from the solution and rinse it with some soap and water.
5. Scrub off the ink transferred onto the PCB with a kitchen scrubber and soap or rubbing alcohol.

fig 7. Etched PCBs

DISPOSAL NOTE: The etching solution eats copper and is somewhat toxic. Hence, it should be disposed of with care. Do not pour it down the drain if your drain system has copper pipes, as it will eat up the copper pipes!

Step Six: Drilling of Holes

Drill holes onto the PCB using the PCB drill. Ensure that the drill bit you are using corresponds to the hole size of the hole you are drilling. If it is bigger, it might remove the copper pad, thus eliminating an area for soldering.

fig 8. PCB with holes of various sizes drilled

Step Seven: Soldering

After completing the PCB drilling, solder the components onto the PCB, and this should finalize your PCB.

fig 9. Soldering process

fig 10. PCB with components soldered

[IlyasOsman]

By @ianmuchyri, on January 07, 2023.