PCB DIY, revisited

[Connoisseur of Distortion]

I have started etching again. why? because i really wanted to make some effects that might suffer from clock whine. to make these pedals on perf, i would have immense difficulty squeezing them into a reasonable box. I just etched a nigh flawless Ultra Flanger using My New System.

My new system is based on existing routines, but a couple of additional steps are added in to make it more consistent.


Preparations! I use Jet Print Multi Project Photo Paper, which seems to give me the best results. Your paper of choice will probably be fine. I get my copies made at Kinko's, because I have no laser printer. Make copies as dark as possible while avoiding noise (extra shadows/ black dots). You should be able to get good, thick toner while keeping the noise level down. THIS IS URGENT! If you have too little toner, your results will be AWFUL.

First, cut / prep the board. I leave more copper than i need on one edge, so that the little hook has something to grasp while hanging in the container.

Second, clean the board. From here on, it's exam gloves! Scrub the board with some fine steel wool until ALL of the surface shines. I used to miss the edges, but now i make sure it all shines equally well. Then, use some alcohol on a kleenex to wipe it down. Wipe thoroughly, then dry with another kleenex. inspect the board, and make sure that no "rainbow" spots have appeared. If they have, use alcohol again and make sure it doesn't dry on.

Third, iron. Place the transfer on the top of the board, and gently move about, touching it to make it adhere. Then, place a piece of ordinary paper on top of the transfer and board, and leave the iron on top to preheat. The paper is there to allow heat transfer while minimizing the risk of sliding your transfer around. After about 5 minutes of preheating, start running the iron around the transfer slowly and firmly. After doing this for a couple of minutes, remove the ordinary paper and start ironing directly, and GENTLY, to the transfer. The circuit should start to show itself through the paper, and by the end you should see the entire circuit within reasonable detail. Iron like this for about 5-10 minutes, depending on whether it's showing itself easily or not.

Fourth, complete transfer. Now, go drop this PCB into a bowl of water. Doesn't matter if it's hot, it's only going in to make it easy to touch. After cool enough (usually about 5-10 seconds), place on a piece of wood and apply acetone to the top of the transfer. The circuit should show through the paper with good detail. Let it sit for about 30 seconds, then wave it around wildly to dry it off. Now go hold your circuit under a faucet running hot water. I use needle nose pliers, but it's up to you. The paper will resist motion, but gently rub it to make the paper form little rolls and come off gradually. Just keep doing this until a corner comes up and allows it to come off. View the amazing transfer you have. Onward!

Finally, etch. I do not have a heat source, but I use an aquarium air pump to run some air into the FeCl3 to speed up the process. Babysit this thing, because the stuff is poisonous, unpredictable, and can completely mess up your board. It will barely move for the first part of the transfer, and will gather speed as it eats away. It takes about 10-15 minutes for etching to complete in my setup. Not bad, all things considered.

EDIT: now, remove gloves  .  But seriously, this is when you should actually remove them. Not any sooner.

If anyone wants to host pics, I have some brand new, lovely boards sitting downstairs. 

[Connoisseur of Distortion]

i just finished etching a String Ringer. This board is massive, and only needed 3 dremel touch ups.

before that, i etched a perfect BSIAB. no work necessary.

last night i etched a rebote 2.5 , and forgot that touching after the transfer can cause spots to not etch properly. bleh. it'll work alright post-dremel.

i am starting to like etching. this is usually my hated part of any project, but now the results are actually decent!

[Paul Perry (Frostwave)]

That 'acetone' stage is a new one on me! I've known people to use acetone to transfer toner (or otehr solvent soluble inks) from one surface to another, but I'm not sure what is happening here, unless the idea is to dissolve the toner in contact wiht the paper while it stays in contact with the copper. I gues timing is critical!!
Great to have one more account of a successful PCB process.

[Pushtone]

If anyone wants to host pics, I have some brand new, lovely boards sitting downstairs. 

Like these?? I get great results using PnP Blue from SB and Tonepad's photo essay.
One thing I learned during this etching is not to have the iron too hot. The toner bleeds or crawls (traces/pads get larger) when iron is too hot. I used setting for polyester this time and traces stayed the same size.

[nunocaldeira]

Are those little ones the migmuff tone control?

If so, whould you tell me where to get the layout??



Thank you,

Nuno Caldeira

[mojotron]

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One thing I learned during this etching is not to have the iron too hot. The toner bleeds or crawls (traces/pads get larger) when iron is too hot. I used setting for polyester this time and traces stayed the same size.

One thing to note is that too much heat is mostly an issue for PNP. For Picture Paper (I use Staples brand...) you want a lot of heat - just as described above.

I have done a lot of boards using a lot of different techniques <search to find my exact steps> and this sounds like a good set of steps to follow - definitely will try the Acetone step if I use Picture Paper again - but I always use PNP these days. PNP makes the whole process quite repeatable and is very quick.

Two things I would add about prepping the board.
1) When I sand it - and I use 220 grit wet/dry sanding paper - sand it from 8 directions (lightly/quickly) or in circular motion. You want to rough up the surface not polish it. Sand the sides/edges really hard at an extreme angle - you aren't putting any traces on the edges so sand enough so that there are no ridges on the edges that would block the toner transfer.
2) When I clean the board - I use acetone and a paper towel - be careful (don't use gloves they will just melt). The board is clean enough when you can wipe the board with a fresh paper towel with some acetone on it and the paper does not show any dirt after wiping it.

[newperson]

Hi,

What containers are people using to etch in?  I have used glass, little plastic trays from part bins, bigger plastic sandwich Tupperware, and the zip lock bags.  But all of these methods causes me only to be able to small boards.  I would like to try to do a full size 8/10 or even 5/8 size board.  Are any of you doing sizes that big?  And if so, what are you putting the acid in, and how are you heating it?

-p.

[gaussmarkov]

i don't etch ... yet ... but i came across this idea and thought it was interesting:

"No Agitation" method of etching PCBs.  A simple alternative for lazy people.

i posted it once before, but i don't think many noticed it.  so here it is again. 

[Connoisseur of Distortion]

the idea behind the acetone stage was to make the paper separate without pulling traces along. I did that waaaay too many times, thanks.

also, thought i'd add another little stroke of genius i had yesterday. to make use of copperclad that has both sides copper, i grind off the copper on one side using a sander. I don't grind down to the base, for that would be quite messy. Rather, i grind until i start to see 'threads' of PCB through the copper, and then i grind on the edges a little extra to help along the etching (which starts at the edges, mind you). Both sides etch in about the same amount of time, and a lot of FeCl3 is saved.

BTW, how does sodium persulphate compare? does it last longer? does it etch cleaner? is it safe to pour down the drain? i have been wondering about this...