My DIY Solder Mask

[Kevin Mitchell]

I thought I'd share a habit I've picked up recently to preserve my boards a bit better. Some times I have to put a board down for a while before finishing it or go in for adjustments later on. One thing that happens is the copper oxidized and becomes dirty and not solder-friendly.

Here's my fix!


I've read around that some people (and old-school production companies) would apply a thin layer of acid free clear coat on the board as a solder mask. So I gave it a shot!

For the image above I used a colored translucent "glass" paint that works on many surfaces. Be sure apply very thin coats. DO NOT OVER APPLY! You need just enough for the board to be covered. For colored paints it's especially crucial so you can still makes out all of the traces on board. I had to do about 6 passes on that board before there were no more unfinished specs. When soldering the paint quickly flashes off when the solder contacts the ready to solder heated pad.

This technique is great for any type of board. Vero, stripboard and home etched boards. I definitely recommend the usual stomp box builders to give this a shot. Unless someone has something to say otherwise!

Obviously don't use a paint that contains metallic properties... Acid free translucent paint (clear coats).

[R.G.]

Does your paint absorb humidity from the air over time?

It's acid free - is it alkali free? Or does it contain another chemical that will react with copper over time?

You're probably fine, but these are things worth thinking about.

[Kevin Mitchell]

Does your paint absorb humidity from the air over time?

It's acid free - is it alkali free? Or does it contain another chemical that will react with copper over time?

You're probably fine, but these are things worth thinking about.

I can't say it does but besides the can itself I wouldn't know where else to look. I've built a few circuits with this paint and basic clear gloss acrylic paint.
Thanks for the info!

[PRR]

Consider Art-Store spray shellac.

It is clear(!).

It burns-off fairly-clean with solder heat.

It isn't likely to be doped with much odd stuff. (OTOH it is not likely to be chemically-pure.)

[deadastronaut]

i use car spray clear coat on my diy pcbs once populated to preserve the copper,

can be soldered through after too...

[LiLFX]

I've always used Krylon clear acrylic. You can solder through it no problem. If you want something more application specific check out the products offered by Humiseal.

[Gargaman]

i use car spray clear coat on my diy pcbs once populated to preserve the copper,

can be soldered through after too...

Over all the components, etc? Is it possible to take measurements with the multimeter after you apply?
I tried my girlfriend's nail enamel to protect the cooper, but I can't take measurements. Didn't try desolder or solder on it.
Am I completely dumb?

[deadastronaut]

not over the components...

just the copper side..

[Gargaman]

not over the components...

just the copper side..

Over all the components, etc?

where is my mind??

making some coffee here by now

[amptramp]

The components can be conformally coated to protect against moisture or contamination.  The solder mask may be the same material but if you need it to be solder-through, you may need a different material.