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Subject: Re: [Homebrew_PCBs] Fiberglass weave present through copper surface? (plus some tips I learned...)

From: DJ Delorie <dj@...>
Date: 2014-05-15

"Peter Johansson rockets4kids@... [Homebrew_PCBs]"
<Homebrew_PCBs@yahoogroups.com> writes:
> I can see where that would be a problem. I am only ∗just∗ making the
> jump from TH to SMD, and I'm starting with the coarsest pitch
> components I can find.

I like 0603 and 0.5mm pitch myself. But I'm "that crazy guy that makes
insanely small pcbs at home".
http://www.delorie.com/pcb/inkjet/insanity_II.html

> It would certainly be possible to drag the iron away from the pads on
> fine-pitch parts and leave them bare.

Design note: if you're hand-soldering fine-pitch SMT ICs (like TSSOP or
TQFP), make the pads on the footprints stick out 1-2mm more than normal.
This gives you some exposed pad to "drag away" any excess solder.

> I've read conflicting reports on the Liquid Tin. Some people love it,
> other people claim it provides little to no long-term protection for
> your boards and doesn't really help with soldering SMD parts either.

It reduces copper oxidation, that's all I use it for. I don't think
it's intended to help with soldering. It "helps" with SMD only because
it's not lumpy solder :-)

> One thing is for sure though -- it does make your boards look
> beautiful!

My favorite "pretty" trick is to use another layer of etch-resist film
as a solder mask, over the tin. It gives a deep blue hue to everything.
http://www.delorie.com/electronics/adapters/r8c-pillar.html