Intro: DIY PCB at Home (Vinegar+H2O2+Salt) and Arduino Airsoft Bomb
This is my first instructable and first time etchina a PCB.
This is more of a how I made my PCB rather than an actual instructible.
For my etching I used a method which was posted a while ago by: Feynmaniac
With his instructable: Here
I am making an Arduino UNO project with a 4x4 matrix keypad and a 16x2 LCD and various other parts.
Also, I am making it a standalone UNO, so I am only using the ATmega328p-pu.
First off, I made the project on a breadboard and in Circuits.io, because I thought I could get a schematic and a PCB from them, but that was a dead givaway, so I tried to do it on my own using other programs such as Altium designer 17, CircuitMaker, and at the end settled with Eagle from Autodesk with a student licence.
Made the schematic, then placed and routed the PCB.
The weird thing is that almost all of my electronic parts are non standard, the keypad has its pinout different than most keypads, the LCD pinout is also weirdly made. Pins 15 & 16 are the first and then they start from 1 to 14.
Made things very difficult to even begin with.
Step 1: The PCB
I made a PDF file with 9 PCB images on it so I dant waste my paper and time. Then cut out individual PCB images and started the good old iron technique. I cleaned the board with acetone. I couldn't find steel wool here, but I figured that a metal dish scrubber should work just fine. After that I did the Toner transfer with my iron to the full heat for about 5 minutes.
Then the board want to a soapy water bath for good 10-20 minutes and peeled the paper away easily.
Checked the transfer and drew on some places where it didn't transfer as good or had a break.
Then I cut the board to a smaller size with a saw.
Step 2: PCB Etching
Here comes the tricky part. I didn't have regular vinegar. I had a very strong essence of 70% so I had to water it down.
So I will give some of my calculations if you happen to need them:
70% - 350ml (0.350 L)
9% - 2.695 L to water down all the 350 ml of essence.
70% : 9% = 7.777(7)
I only need about 100ml, so:
100ml : 7.7 = 12.9 ml of essence for those 100ml of vinegar.
According to the PCB etching guide by Feynmaniac, I need a ratio of 2:3. 2 parts of H2O2 and 3 parts of vinegar.
So basically, for easier calculations, I made the ratio 1 : 1.5
I had 100ml 3% H2O2 and 150ml 9% Vinegar. That meant I need to add more essence, which is about 20ml for that 150ml of vinegar.
Also I added a tablespoon of NaCl (salt) and mixed the whole liquid together and put my PCB in there.
I put the container inside of another container with hot water, so the reaction would go faster.
The whole etching process took about an hour. At first it didn't go that fast, so I added a bit more essence, salt and H2O2.
After the naked copper had been etched, I rinsed the board with water, dried it and then removed the toner with nail polish remover with acetone.
All that's left is to drill the holes and solder the components.
That was my first try at making the board from start to finish.
I will add more images of the finished project.