Introduction: DIY PCB at Home (Vinegar+H2O2+Salt) and Arduino Airsoft Bomb

Hello!

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.

Comments

author
mkrobert made it!(author)2017-03-14

In response to the vinegar strength, vinegar is acetic acid (usually between 5%-20%). You might find an etching liquid of that strength or maybe ask a pharmacist.

author
oragamiunicorn made it!(author)2017-03-05

I've never come across concentrated vinegar 'essence' is that a catering strength thing? Do you know what percentage an off the shelf white vinegar would be? I'm hoping i can use this technique with kitchen white vinegar?

author
deskpro256 made it!(author)2017-03-07

Hey there! I live in Latvia, a small EU country, we had a company producing this strong concentrated 70% vinegar acid, but after EU standards didn't allow these to be produced anymore and some people bought these while they could. I had this laying around at my mother's house, she uses it to also make regular vinegar for making pickles.
We have about 9% vinegar here, but after searching on Google a bit regular white vinegar is about 5-20%. Depending on where you live it may vary. I would suggest checking some stores or ask your parents about it.
Also check the instructables thread I mention in the beginning of my instructable.

If your vinegar is a bit weak like those 5%, maybe try heating it a little to get the water out and have a bit stronger vinegar.

Anyway, I'd say go ham with it and try a small board just to test. Remember to keep agitating the board in the liquid and heat up the container that has the liquid, so it has a stronger eaction.
Cheers!

author
oragamiunicorn made it!(author)2017-03-08

thanks for your response, I don't think I can get hold of this stronger vinegar, I might try concentrating white vinegar by simmering it off as you suggest, though I'll have to do it outside, the fumes from heating vinegar are horrible. Does anyone know how I can test the strength? I'm assuming if I boil down 1 litre of 5% vinegar to 500ml it'll be 10% strength?

author
Swansong made it!(author)2017-03-02

Looks good :)

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Bio: Hi, I am a 22 year old electronics engineering student who likes to make projects, learn new things and also reuse old electronics for new ... More »
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