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Subject: Re: [Homebrew_PCBs] Re: Fine soldering iron

From: Johnathan Corgan <jcorgan@...>
Date: 2004-03-18

ghidera2000 wrote:

> As for the QFP - Some things I've read said that going with a fine
> tip might actually be harder than going with a wide one. They said
> go wide and solder several pins at once. Check for bridges when
> you're done and remove with a soldering wick.
>
> I haven't tried a QFP but I have tried some SOTs this way. Seems
> that the solder rarely bridges unless you put loads of it on. Even
> then I usually just turn the tip sideways and reheat one of the pins
> and the bridge melts away in an instant.

Yep. The "solder blob swipe" technique works especially well when there
is a solder mask layer on the board, I never seem to get bridges.
Without the solder mask the bridges are much more likely but nothing a
little wicking won't remove (as you mentioned.)

Just remember that flux is your friend. "Be the flux."

Lately, though, I've noticed that there is sufficient solder finish on
the SMT pads from my proto manufacturer to just heat the pin while
applying slight pressure on the body of the part. The pad finish melts,
bonds to the pin, and it's done! I've done many 0805 parts and even a
couple VQ44 packages this way. It seems to work well electrically and
mechanically but I don't trust it that it could be so easy (these are of
course home projects so I don't have to worry about commercial
quality/reliability standards. Still.)

-Johnathan