Tutorial : Making your own PCB

CodeMonk

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I ran this by LtDave32 (and he ok'ed it) a while back, then just totally spaced out on it. (Chemicals can be fun, but hazardous kiddies).



Making your own PCBs tutorial

How do you make your own circuit boards?
Its a lot easier than you think.
But there are some precautions you need to take.

I'm going to show you the low budget way to do it.
There are several ways to do it, but I like the low budget way, so that's what
I am going to show you.


First off, stuff you need:
Computer
Program for designing circuit layouts
Laser printer (Ink-jet won't work)
Photo paper made for laser (NOTE: You can also use Presentation paper)
Copper blanks
Etchant
Drill Bits (Recommended sizes. YMMV).
....For component holes: 0.035 - 0.038 (#60 - #65)
....For wire holes: 0.040 - 0.045 (#54 - #56) - I use 22 gauge wire.
Drill or Drill press (I paid $50 for my drill press)
Iron (the type you use for clothes)
Plastic tub
Safety glasses
Rubber gloves
#0000 steel wool and/or 400 grit abrasive paper. Scotchbrite pads can be used as well.
Small air pump (not necessary, but speeds the process up like 400%)
Plastic or glass container
LOTS of water standing by (For safety reasons)


OK, first up, VERY IMPORTANT:
You will be using chemicals, some of which are hazardous...

For disposal, contact your local waste management facility

MSDS stands for Material Safety Data Sheet

Sodium PerSulphate MSDS
http://www.sciencelab.com/msds.php?msdsId=9927601

Muratic Acid MSDS
Department of Visual Art | Department of Visual Art

Ferric Cholride MSDS
http://www.sciencelab.com/msds.php?msdsId=9924033

How should you dispose of muriatic acid



Up next, the Layout.
You can design you own or use one of the many available. If a DIY pedal exists,
someone has likely already done a layout for it.

For simple layout software, I prefer DIY Layout Creator (diy-layout-creator - Free multi-platform schematic, layout and guitar wiring diagram editor - Google Project Hosting)
You can create a layout in 30 minutes or less. It can also take days or weeks.

Laser printer. Ink-jet printers will not do. Laser toner is plastic based which you will soon see is critical to this method working.

Copper blanks you should be able to get at any electronic hobby store.
Avoid the double sided ones unless you really need them.
Radioshack even sells them. You can also find them at Smallbear
(http://www.smallbearelec.com/Categories.bok?category=PC+Boards+and+Prototyping&searchpath=2418184&start=9&total=23)

Etchant. Several options here. Sodium Persulfate Powder, Ferric chloride, Or a combination of Muratic Acid and Hydrogen Peroxide (Which is what I use).
With the Muratic Acid and Hydrogen Peroxide you can have about 4 gallons of etchant for less than $20. The others are $10 or more per quart)
But Muratic Acid is very caustic (Hence the "LOTS of water standing by" bit above).
Ferric chloride you can get at most electronic hobby stores (even radioshack)
Muratic Acid you can get at most large chain hardware stores or pool cleaning supply stores.
Hydrogen Peroxide can be found at any drug store/pharmacy.

Sodium Persulfate Powder, I have never used so I can't comment on that.
Ferric chloride:
Downsides, while only about $10 a quart, it etches a little slow and its a dark red so you can't easily check the progress of the etching. Also, anything it touches it stains. Get it on your hand for even a few seconds, it stains.
The stain will be there for awhile.
Upside: less caustic to skin

Muratic Acid solution:
Downsides, very caustic. Will burn your skin. That why I keep lots of water around and wear the gloves.
Upside, costs much less than Ferric Chloride.

The iron, anything works. I paid $4 for mine at Walmart.

Plastic tub. I personally use one that previously held a gallon of ice cream.
This is for after you apply the layout from the photo paper to the copper.

Safety glasses. We may be working with some nasty chemicals. A full faced safety shield is better.

Rubber gloves. I prefer Nitrile gloves as they stand up much better to acetone than latex does. Cost is about the same.

Plastic or glass container for doing the etching.

Long sleeve shirts should be worn when handling the etchant.

-----------------------------------------------

Ok, lets get started shall we?

Some equipment and safety info first:

Here is where the "LOTS of water standing by" is for.
2 - 5 gallon buckets. Time to change these soon.
We are going to be using the Muratic Acid and Hydrogen Peroxide solution for etching. Its a caustic solution.
Muratic Acid is used to clean pools and grease stains and such from concrete driveways.
If I get any on me, I dip my hands in these buckets ASAP. It can burn if not taken care of quickly.



Nitrile gloves.
You can use latex or vinyl but I find that nitrile is more durable with acetone and the etchant. Although some brands can tear
easily when you put them on.




Here is what happened after I left an open container of the solution overnight in my garage.
Thats my drill press. It was all shiney before.
So always seal any solution after use in a plastic or glass container (No metal containers or lids).




Here is what we are going to be etching a PCB for.
Since this is just for a test, no need to design for the
transformer.




Ok, so now we need to design the circuit layout.
Using DIY Layout Creator (diy-layout-creator - Free multi-platform schematic, layout and guitar wiring diagram editor - Google Project Hosting)
I created the layout. I made it fairly open so you can see the circuit traces easily.
Generally I design boards much more compact than this.
You are going to need the layout so you know where all the parts go.
I also left out the switch labeled "S1". I personally like the sound with the switch bypassed.
I think the harmonics are sweeter.
Also to show that its sometimes relatively easy to mod a circuit.
R1 is a resistor
C1 - C5 are capacitors
D1 - D3 are diodes
Q1 is a transistor
When assembling take care the orientation of Q1
P41 is the volume control

You can find all these at Radioshack even.

Anyway, I am hoping anyone interested in this knows something about the different components
and how to solder and hopefully able to read schematics.
If you lack any of this knowledge, might I suggest the following sites:


How to Solder
How to Read a Schematic

Diy Layout Creator has an option for saving the layout as a GIF file (listed under the "File" button), "Render Image"




Ok so we created a layout. Now to get the circuit itself from this design
Diy Layout Creator has an option for this as well (listed under the "File" button), "Render PNP"

The text I added. Take care that its mirrored. Any text you want on a circuit board has to
be done mirrored.
For the image properties, set Pixels Per Inch at 200.
And that gives us this:




Now, using a laser printer, print out the circuit on PHOTO PAPER MADE FOR LASER.
I usually print out extra circuits because my laser printer is kind of a POS.
I can choose the best image.




Next you cut out your copper a little bit bigger than your design.
Then using the 400 grit abrasive paper to clean the copper. Oxidation is very likely on it and needs to be cleaned off or the circuit design will not stick to the copper properly. Sand in a circular motion
until it looks clean.
Then clean the board off with Acetone.
Wear gloves and safety glasses while doing this.




Now we get ready to apply the design to the copper board.
Notice how I don't let my bare fingers touch the board.




Now we lay the circuit FACE DOWN...

 

CodeMonk

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And we begin using the iron.
Set the iron on the hottest setting (usually Cotton).
Apply light to medium pressure, moving in a circular pattern.
For a board this size, 45 seconds to 1 minute should be fine.
It also helps if you hold down a corner of the photo paper with something (NOT YOUR FINGERS!),
until the circuit pattern starts to stick to the copper.
This part can be a bit tricky and may take some practice. it took me several tries to get it right
the first few times I made my own boards.
For larger boards, it will take more time. Also for larger boards, I generally use a toaster oven I use
for baking pedal enclosures after I paint them. What I do is heat up the board first. About 150 - 200 degrees should be fine.
This only applies to larger boards. For small boards its not necessary.
If you use a toaster oven for either purpose, DO NOT USE IT FOR FOOD EVER AGAIN!




We now have the circuit transferred to the copper, time to give it a bath.
I use warm soapy water. What we want to do is soften the paper so it comes of easily, leaving the trace on the board.



Now let it soak for 10 - 20 minutes.
After we remove the board from its bath.
You can just use your fingers and a toothbrush to remove the wet paper.
And here is what we get from that:




Ready for etching!
Next step...
Now what I have done here is taken some strips and little squares of plexiglass to create something
to hold the PCB at the proper height. We want the board raised up enough so that it is just barely
in the solution.
The mixture of the solution, well, ask ten people, you will get ten different answers.
As for me, I use a mixture of roughly 3/2 - Muratic Acid/Hydrogen Peroxide.
Pour just enough in the barely cover the board.

Muratic Acid and the Hydrogen Peroxide.
The little cup on top of the peroxide I use to measure out the chemicals.
measure carefully.




Here I use a small air pump you can get at anyplace that sells fish for $5 or so.
Buy it at an electronics supply store and its around $10. But you also get the hose and something
to attach it to. What you want for this to do is create multiple small bubbles underneath the board.
This greatly speeds up the etching versus just letting the board sit it the solution.
Another option is to continually rock you etching tank back and forth.
Trust me the air pump is the way to go by far.
What you want if using the air pump is something non-metallic to plug the hose into with multiple
holes in it that blow air bubbles at the board. I use a hard piece of rubber. A real bitch to drill holes
in but I have a big piece that 1/2 inch thick and about 5 x 5 feet.

Now here we are etching. Notice the bubbles. And the shield.




Now we have our etched board (ok, I took it out to soon and left a tiny piece of copper there.
Not to worry in this case. Its away from the circuit and will likely be trimmed anyway.




Now you see why the text was printed in reverse :)



Now we start drilling the holes needed for the components and wires:
Note #2: Before you start drilling make sure that the little holes the components will go through are clear of the toner. It helps to keep the drill bit from drifting or wobbling.
Those drill bits are very thin and bend easily. And fiberglass tends to dull the drill bits a bit. Carbide bits are an option but they cost about $6 each. regular ones, you can get like 10 of them for a few bucks.
(Sorry, a little blurry)
NOTE: make sure you wear eye protection and some sort of mask to prevent inhaling fiberglass dust
(Another blurry picture)




After we drill all the holes (see list for drill sizes), we need to debur the holes and remove the laser toner.
Use the 400 grit paper to remove the burs and Acetone to remove the laser toner

And we get....





Nice and purty

And there we go, ready to be assembled.

Any questions, problems, etc, reply in this thread.

Enjoy...and be careful.



-----------------------------------------
Some additions...


Here is a little addition.
Sometimes, especially when you first start doing board etching, the toner material doesn't stick to the PCB in some locations.
Here is a "photoshopped" example of what I mean:


See how some of the trace is not there. Two choices here. Either take some Acetone, remove the toner and start over.
Another option is to simply use a Sharpie to cover the little trace section that is missing the toner.
And yes, that really works.

------------------------------------------------------


For those of you that have actually made your own PCB's, this is another step I have been doing lately (About a year or so).
Plating the PCB.
Exposed copper can get corroded and rather nasty after time. Especially if you live on/near an ocean/coast (or other body of salt water)

I have tried several methods of protecting/plating the copper and this method seems to be the easiest, lowest cost, most durable, and quickest.
Plating also makes it much easier to solder as the plated material accepts solder far better than bare copper.
It only takes a few minutes. Other methods I have tried can take up to an hour, which includes preparation of the solution.
I use a product called "Liquid Tin". Its available from MG Chemicals


This is what I did this morning.
.
Use a small NON-METAL container, just large enough to hold your PCB.
Place your PCB in the container and pour in just enough of the Liquid Tin to completely cover the PCB.

LIQUID TIN:


CONTAINER:


DURING TIN (After about 10 seconds):


AFTER TIN:


HALF TIN (I just tinned part of the board (Store bought from RadioShack) so you can see the difference):


It take less than 5 minutes for the PCB to become fully plated. Usually just 2 or 3 minutes.
I have left a PCB in the solution for up to half an hour with no apparent detrimental effects to the board.

After the tinning process, just use liquid soap and warm water, to clean things up.
Then solder away.

Afterwards, I pour the used liquid into another NON-METAL (No metal lids either) container. It is still good and can be used later.
Some people just pour it back into the original container.
While I have no experience with just pouring it back into the original container, I have heard that it may weaken the solution.
 

H.E.L.Shane

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I used to use the photo reactive boards, print the circuit on a clear transfer and then expose the board to UV light.. then do the etching process..

If I remember correctly... I did it because i didn't have a laser printer at home...

I'm thinking about getting back into making boards again.. might have to look at all the ways to do it...
 

CodeMonk

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The photoresist method, you can get some amazing detail with that method.


------------------------------------------
ANOTHER UPDATE

I few months ago, from the suggestion from someone on another forum (With a few of my own twisted added)...
An upgrade to the bubble method.
(May look a little ugly but it REALLY IMPROVES THE BUBBLE ACTION PART).



Parts used (Total cost about $20 or so):
(You can get all of this stuff at some place like Walmart, except maybe the hard rubber bits).
  1. Hard Rubber.
    If you know someone with a horse trailer, try and get some of the rubber floor padding. has roughly the same consistency of a car tire, but its flat. Or something similar.
  2. Air Stones.
    Can be had at any store that carries pet fish/fish tank supplies.
  3. Hose to attach to said stones as well as a few adapters that fit the hose. A few T adapters as well as some 90 degree adapters are preferred.
  4. Air pump. The one I use I think is like 2,200 CFM (Or maybe it was CCM). (might be over kill). It was about $10
  5. Plastic toothpicks. These help to keep the PCB just above the air stones.
  6. Latex or silicone caulking goop.
  7. Plastic container.
  8. Drill several small holes in the rubber at various locations. Stick the toothpicks in these holes.
  9. Attach the hoses and fittings to the air stones so that they fit ABOVE the stones.
  10. Put some caulk on the bottom of the stones and the hard rubber and push the down in the bottom of the plastic container. Try to evenly space everything.
  11. Fill in the gaps with the caulking.
  12. Let cure a day or two.
  13. Attach hoses between air pump and the etching container.
  14. Start etching.

THIS METHOD SPEEDS UP THE ETCHING PROCESS BY QUITE A BIT SO KEEP A CLOSE EYE ON THE PROGRESS.

If anyone needs clarification on ANYTHING in this tutorial, please feel free to ask.
 




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