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I know how to do a PCB until this step (below image) ugly and not safe by short-circuits.

I found this PCB Plating Tape on Aliexpress (Link to the aliexpress product. I'm not the seller) which I think I can use to mask my PCBs but I don't know how can I leave some copper uncovered (like below image) so I can solder components later.

  • Do you mask PCBs with a tape or some kind of resin spray?
  • How do you keep some copper uncovered for soldering?
    • With tape - Cut it away after applying?
    • With tape - Heat interested area with the welder so it magically goes away?
    • With spray - Cover the area with something before of applying and then remove the cover?
  • Do you use rivets (or Annular ring) on holes?

Sorry for the huge list of questions, I am a big newbie.

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  • \$\begingroup\$ Have a look at this EEVBlog video to see how this is done in a professional environment: youtube.com/watch?v=rEB0pl8a5C0 They use paint for the solder mask. Some hobbyists use transfer papers I believe. \$\endgroup\$ Jan 4 '17 at 16:14
  • \$\begingroup\$ By far the easiest (at least for me) is to use a spray on conformal coating post board assembly. There are many conformal coating spray and paint solutions available. \$\endgroup\$ Jan 4 '17 at 16:29
  • \$\begingroup\$ That board "needs" solder mask like a cat needs pajamas. \$\endgroup\$
    – JRE
    Jan 4 '17 at 20:01
  • \$\begingroup\$ If you want to have double-side boards with plated through holes and soldermask, the easiest is to order them to a cheap PCB fab house. The price they offer now could even beat a home-made PCB with the features you request, the quality will be better, and you'll experience less pain this way. I'd say that any try to make home-made PCB more advanced than what you shown on the first picture is a waste of time. \$\endgroup\$
    – dim
    Jan 5 '17 at 9:39
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Solder mask uses a special kind of paint. It cures (hardens / dries) using UV light.

The paint is applied to the entire board, then a printed mask is applied over the top. This mask has the parts that you want open in black and the parts that you want covered in paint transparent.

The paint is then dried in an oven and cured with UV and the mask removed.

Where the mask was opaque the paint will not have cured and can be washed off with a suitable solvent.

You can buy the paint on eBay in syringes. If you are careful it is also possible to apply the paint with a very fine paint brush leaving the apertures you need clear. Then bake it at 80C until dry and leave it sat in bright sun for 30 minute's or so.

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  • \$\begingroup\$ Thank you so much, your answer was very helpful! One more question: do you think the product I linked suits good for this process? I mean, do you think it is UV curable? \$\endgroup\$ Jan 16 '17 at 13:55
  • \$\begingroup\$ @CliffBurton Unlikely, that's tape, not a paint. This is the paint I use: ebay.co.uk/itm/112221676097 \$\endgroup\$
    – Majenko
    Jan 16 '17 at 13:57
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Generally it is best to design boards without surface traces that could potentially short to some other conductor that will be in contact with the board.

Even without soldermask, PCB substrate is not very attractive to solder, so even the slightest care in assembly or (or at worst removal of extra solder with fine braid) is usually enough to prevent shorts to adjacent pins/traces.

In your case it appears that you may have a sub-module apparently having conductive regions on its lower surface that you are worried will short against your handmade traces.

While a commercially applied soldermask might perhaps be contemplated for protection against that, I'd hesitate to rely on a hand applied one as an insulator.

Your best bet is probably going to be some thin polyamide (kapton) tape or other physical insulation, especially if you can put manual attention into making sure that the contacts are reliably made despite any slight vertical spacing introduced by it.

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