DIY solder mask theory (And a big one, need helllllpppppp)

[darron]

  I'll 3rd the "learn to solder better" sentiment. Also make sure your using the proper equipment, new tips, proper wattage, .020 dia.(or less) solder, etc.
  Jered

yeah, but you're going to have to spray the board at some point anyway to protect it. so i'm thinking this would be a really good idea. i can solder (: i guess.... i haven't tried smd yet or anything (:

i'm just wondering if anyone knows which paints will work. i guess i'll just have to experiment when the time comes.

[culturejam]

This article might be of interest:
http://www.sigcon.com/Pubs/edn/PassivationandSolderMask.htm

I'll second the idea that a conformal spray coating is probably a better idea.

[bighead]

I use clear fingernail polish to paint over the traces. It works great.

[Jered]

  I'll 3rd the "learn to solder better" sentiment. Also make sure your using the proper equipment, new tips, proper wattage, .020 dia.(or less) solder, etc.
  Jered

yeah, but you're going to have to spray the board at some point anyway to protect it. so i'm thinking this would be a really good idea. i can solder (: i guess.... i haven't tried smd yet or anything (:

i'm just wondering if anyone knows which paints will work. i guess i'll just have to experiment when the time comes.

  Well then, I use Circuit Coate Uralane 8267. Dries to the touch in 30 minutes, complete insulation in 24 hrs, and fast repair. Just solder through and respray.
  Jered

[darron]

  I'll 3rd the "learn to solder better" sentiment. Also make sure your using the proper equipment, new tips, proper wattage, .020 dia.(or less) solder, etc.
  Jered

yeah, but you're going to have to spray the board at some point anyway to protect it. so i'm thinking this would be a really good idea. i can solder (: i guess.... i haven't tried smd yet or anything (:

i'm just wondering if anyone knows which paints will work. i guess i'll just have to experiment when the time comes.

  Well then, I use Circuit Coate Uralane 8267. Dries to the touch in 30 minutes, complete insulation in 24 hrs, and fast repair. Just solder through and respray.
  Jered

wouldn't the mask be better if you couldn't easily solder through it?

i'll try some conformal spray from RS components. they have silicone and acrylic. one of the silicones is red though, and they don't mention the colour of the other. i wanted the blue mojo ):

[juse]

I'll 4th the 'better solder' technique. Soldermask is really for wave solder applications, unless you are trying to do a .4mm BGA  by hand or something. If you use less solder, the right heat & have good timing, you'll be fine.

[R.G.]

Doing a proper solder mask is equal in difficulty to putting on etch resist if you use photo-techniques. It's much harder if you try some other technique.

The only solder mask technique I know of that's workable at home without either photo or CNC equipment is to put little paper dots on each copper pad, spray the board with lacquer or equivalent, then pick off the dots, leaving the copper pads.

Frankly, learning to solder better is probably going to save you time over the long run.

Historically, solder mask was invented so boards could be wave soldered.

[darron]

i re-brought this one up because i'm mainly interested in protecting the board. since i'll be using the laser it really won't be any extra work at all to do a solder mask. it would loose the cool diy look but i'd even be happy spraying a clear (? insert paint here that won't make nasty fumes). i don't actually have any problems with soldering or bridges, and the only place where i sometimes get problems is around pads that i made too close, which the mask probably wouldn't help with anyway.

other than the conformal spray, which i'll need to order, i guess it's just something that people here aren't really experienced with. i'll need to experiment to see what chars, what smokes, etc. maybe engine spray...

[Jered]

  Circuit Coate is clear.

[darron]

  Circuit Coate is clear.

didn't you say that you can just solder right through it though? will it be happy with populating a whole circuit board? i've never actually used the commercial circuit protectors because i've found anything with high resistance does the trick of protecting from oxidizing, and i always have sprays lying around.

[juse]

i re-brought this one up because i'm mainly interested in protecting the board.

What are you trying to protect? If you are trying to keep the copper from corroding or something like that, then tinning the traces is a good idea. I can't think of anything that would be threatened with the traces tinned, unless there was abuse involved. Assuming corrosion was your nemesis, keeping all of the metal surfaces covered/sealed with the same type of metal would pretty much prevent this because corrosion gets its start where two or more different types of metal are in contact with each other & most component leads are tinned, so tinned traces would even it all out. As long as your tin job was thorough, I foresee no problems.

[darron]

i re-brought this one up because i'm mainly interested in protecting the board.

What are you trying to protect? If you are trying to keep the copper from corroding or something like that, then tinning the traces is a good idea. I can't think of anything that would be threatened with the traces tinned, unless there was abuse involved. Assuming corrosion was your nemesis, keeping all of the metal surfaces covered/sealed with the same type of metal would pretty much prevent this because corrosion gets its start where two or more different types of metal are in contact with each other & most component leads are tinned, so tinned traces would even it all out. As long as your tin job was thorough, I foresee no problems.

yes. i meant protecting from corrosion. i guess tinning would look just as cool (:

how do you go about doing it? i saw clip on youtube where he coated the board and then hit it with a heat gun (i have one). i think he used zinc or something for that though. or do you mean just covering the whole board with solder. i suppose i'll check out the electronics places when i am in there next. i like the idea that i could tin it and then leave it forever exposed and solder on it whenever i wanted, so i wouldn't sort of in a rush to get it done that night or the following for example.

i still wouldn't mind trying the solder mask because it should be really easy to do, and i haven't seen a DIY pedal posted here for someone who's done it, and i want to be the first (:

thanks juse

[frank]

Well you could do it with wave solder machine I think.  It's a rocking heated pane with solder in it. When the solder waves passes underneath and every copper that is there is covered.  I saw a small machine at the store but don't know how $$.
Perhaps it will help ?
Frank

[darron]

Well you could do it with wave solder machine I think.  It's a rocking heated pane with solder in it. When the solder waves passes underneath and every copper that is there is covered.  I saw a small machine at the store but don't know how $$.
Perhaps it will help ?
Frank

sounds like heaps of effort to get a board done. but a rocking heated pane also sounds like it would be really useful for etching.

[frank]

HA HA,
It heats way too much.  Imagine the fumes

[darron]

i was hoping that it might come with a thermostat control (:

i once left a whole box in acid to etch in a fridge (not a cold one, i use it for spray painting). half an hour later when i opened it i realised how much fume is actually released. nasty stuff.

[frank]

I was reading your thing yesterday and it poped out.
Darron I think I have a solution.

My aunt is making Ukrainian eggs for easter.  I used to do that also.  The principle is that you cover with bees wax the places that will not be dyed.  So you have:
-  A candle
- Bees wax (sticky) Perhaps you can use something else that cleans out better.
- and a instrument that is a very small metal "funnel" at the end of a stick (some use an used shoelace). there are many hole size in the funnels for different width of marks.

What you do is that you heat up you instrument over the candle and "take a spoon" of wax with the funnel.  The wax melt in it and don't flows till you put it against the egg (well your copper pad)
Spray with lacquer and wait it drys

Then heat a bit at low temp in a small oven, and try to take off the wax.
I think you will have to find a good combination of soap/solvent to clean the rest.

I think you could buy all size of those for very low cost on internet.

Keyword:  This art is called:  pessankas  in Ukraine.

[R.G.]

I came up with my own tinning process. It's common in the industry - or used to be, before solder mask was common - to roller-tin PCBs.

Did you ever spend any time in the back of a snow-ski rental shop? They have a machine there for waxing skis. It's a pot of molten wax with a large diameter metal wheel which spins slowly above it, dipping the wheel into the wax and rotating above the wax. The wheel gets coated in molten wax - and you just pass the wax-ready ski over the top of the wheel as it rotates. A nice thin coat of wax is deposited onto the ski.

So it is with roller tinning. A metal roller is rotated into and out of a pan of molten solder. The wheel is tinned steel, and carries a thin layer of molten solder on it as it rotates out of the pan. To tin a PCB, you take the freshly etched PCB, paint it with flux, pre-heat, and then just pass the copper side over the top surface of the wheel as it rotates. A thin layer of solder is deposited only on the copper.

The hot vat of solder is dangerous, but I came up with a simpler, smaller process. You go to a plumbing store and get a 6-8" length of heavy brass pipe. At home, you arrange a long handle on the pipe from the middle so the pipe looks like the cross of a "T". You heat the pipe by blowing the flame of a propane torch through the middle. For first prep, sandpaper the outside of the pipe, paint on flux, then heat and tin the pipe with solder.

To use it, you lay your PCB down, copper side up, and paint with flux. Then you heat the brass pipe and load it up with solder, maybe laying a few niblets of solder onto the PCB to replenish. When the pipe is good and hot, well above solder melting, you squeegee the pipe across the PCB copper side. The pipe is coated in melted solder and transfers a thin layer to the PCB. With practice, it's easy and fast, and you don't have to run a solder pot.

I first posted this about eight years ago.

[frank]

Oh good idea RG,

That is very fun to talk with experienced guys like you.  Was there any other solutions that were tested and that worked for some?
Oh maybe it's asking too much! How can we get back that far in time on the subject on this site?

Frank

[darron]

frank. the wax idea sounds like it would probably work really well. maybe something for Zben3129 to try. i actually want to spray the whole board with a paint and then use the same laser engraver that i made the board with to quickly take off the paint on the pads. all i'd gave to do is modify the original artwork so that it had only the pads and not the traces. the laser takes acrylics, enamels, and urethanes right off the coper and fiberglass. i mostly just wanted to know which paints people use to make the soldering masks. maybe i should have opened another thread, but this was the closest thing in the search and wasn't very old.

R.G.'s idea look like it would be a bit of work to setup, but he says it's pretty easy. I've done screenprinting myself which is a pain so i doubt its as hard as that. it would be good to save those instructions.


i found the youtube video too!

check out what he does at the end of this... he somehow gives it a nickel coating. looks simple enough. anyone ever done that?
http://www.youtube.com/watch?v=8NhNsNw5BfU