Raspberry Pi Homemade Custom Expansion Board

Since 2015 i am improving this great project to have an almost unlimited custom media centre on my car. One day i decided to bring organization to wires on there with a custom home made pcb board . Pictures above are on broad prototype stage , so there is some wires spread.This board can be modified to your own needs if know how to use CAD software.

USE IT AT YOUR OWN RISK . SOME STEPS DESCRIBED ARE DANGEROUS IN MANY WAYS (SOLDERING WITH HOT IRON, CHEMICAL PROCESSES,ELECTRICITY,ETC ) . BE CAREFUL

media centre website

Step 1: Required Tools

• A manual driller
• Iron solder
• solder
• Vacuum desoldering pump
• Photo paper

Step 2: Material List

• ferric chloride
• phenolite plate
• pin header 2x20 for raspberry Pi 2
• pin header single line

Step 3: Software

Since it is not the point of this instructable , i am just attach the file containing the file to mod as your needs . Software used is EAGLE CAD 7.5.0 freeware version:

Easily Applicable Graphical Layout Editor

Step 4: Exporting Layers Monochromatic

Eagle cad has an option to export file as image,but before some layers must be hidden:

NOTES:

• Some layers are hidden (we dont want them printed)
• As this one is a double side board there are 2 exported images to be done(top and bottom)
• export image as 300 dpi (option monochromatic must be checked)

• After exported use another software(i used GIMP) to paste many times on the same sheet and then export as pdf.

DO NOT SCALE IMAGE!!

Step 5: Toner Transfer

1. Cut phenolite plate near to the size of raspberry board
2. Drill the holes is a good idea to make photo paper match the board size and right positions
3. You can drill some of the holes on pin header on the paper and the board and use a pin to match positions
4. Cut photo paper a little bit bigger to use some tape ,since both top and bottom are on touch with the board use some tape to keep it together
5. Cover the prepared board with some old cloth(t-shirt maybe folded) on both sides
6. Use ironwork for some minutes on maximum temperature on both sides

Don`t feel bad if not get it first time . Just practice give precision to know the right way . Look at the pictures my first attempts (fail,fail,fail) and it was just a single side board without ground plane. Now i am able to make a double-side board .

Step 6: Cleaning Board and Etching Solution

1. Once tone transfer is ready is time to remove photo paper ,clean it with something to remove paper leftovers but no remove toner.
2. Prepare ferric chloride following instructions from the seller
3. Add a sewing thread in oneof the holes on the board
4. Sink the board on the solution and left it there, from time to time check it and make some movements to dissolve undesired copper layer, repeat this process until only thing left are pcb lines.
5. After dry and clean use steel wool to remove toner and reveal copper lines

The attached project here is for a double side board and i do not have pictures of etching process anymore

Step 7: Drilling and Soldering

As a homemade board and being a double side the cheap way to connect top to bottom is to use some wires soldered. Small board is not a problem.

1. Use manual driller tool to make holes carefully
2. Attach pin headers and components
   
3. Solder everything

Some steps more are necessary to finish and make it protected from handling but i did not complete this stage.

Step 8: Mounting and Testing

The board on the picture is not yet the double side from here cause i am improving it to have a better look but the features are almost the same .

• FM breakout board SI4703
• GPS module serial
• 2 rotary encoders

CAR-PC

Custom expansion board