This development is very basic. It provides the GPIO in the form of header. As i will be using this board for rapid development and learning different coding practices.
I designed this board in KiCad – a open source l tool. From schematics and PCB layout is designed in this software suite.
Here are the schematics and PCB layout.
As i don’t have a laser printer i used the free hand sketching of traces. It is a very long and tedious process. After tracing with permanent marker and letting it dry it for few minutes. I etched this PCB in ferric chloride solution. I use very diluted solution, few grams of ferric chloride in around 200 ml water.
Total Etching time is around 40 minutes, After the board has been etched it needs to be cleaned thoroughly. I used utensil cleaning powder for that. And rinsed the board under water. And then let it air dry for few minutes.
The development is created. But there are few issues that came while testing the board. When i tested the board the chip does not responds. While checking for shorts or no connection on the PCB. I found that capacitor is not blocking the alternating signal. rather it is showing a short. So i had to change the 22pf capacitor with a new one and the board now works perfectly fine.
Well after you have built your circuit. You need to realize that circuit to test or deploy.
Single Layer Non-Commercial PCB Fabrication Process Sequence
Make Your Schematic in any EDA tool like KiCad, Eagle, Express PCB, Proteous. Note: These EDA tools are not inter compatible with each other so make sure to use the appropriate tools
Make the PCB Layout using EDA tools.
Now there are two type of output 1. Graphic output (PDF, JPEG, BMP, SVG) 2. CNC text output file or Gerber files
After you made you PCB layout. The base file consist of copper layer and silk layer. Copper Layer: This where all your traces (connecting wires) reside. Silk layer: This layer consist of the graphic layout. It for the accessibility of the user for easy insertion and Post production annotations. You can avoid this if want.
Two methods of etching 1. Tonner transfer : In this method the plastic tonner of the laser printer is transfered to the PCB by the application of heat. Heat can be applied by using the Laminator or the cloth iron.
2. Photoresist method : This is an old method. It produce neat result but it takes a lot of step for understanding. Three steps of photo resist development. a. Apply photoresist film b. Apply Mask c. expose the film under UV light : This can be done by placing the copper clad board into bright sunlight for a brief period of about 10 minute(try a test pcb for the correct exposure time) or you can place the board under a UV LAMP d. develop the photoresit by submerging the board into a solution of a sodium carbonate (1 gm of sodium carbonate into 500ml of water) e. etch the board by submerging the board into any one of the following solution. 1. ferric chloride (dissolve ferric chloride into 200ml-300ml water till it becomes saturated) 2. Muriactic Acid Solution (muriatic acid solution) (Old name for HCL) 3. Copper sulfate + sulfuric acid 4. Nitric Acid 5. Hydrochloric acid + hydrogen peroxide f. rinse the board in water. g. photoresist removal : submerge in sodium hydroxide solution h. rinse the board in water.