[sdiy] I must be really strong, cuz I've lifted so many pads!

[David Cornutt]

On Sep 6, 2004, at 9:49 PM, James Patchell wrote:

>
> 2. If they are solder plated, were they bright shiny solder plated, or 
> dull oxidized...again, need to make them bright and shiny...

Yep.  This is a board that I purchased partially assembled.  I think it 
had been
sitting around for a while.  I went over the remaining un-soldered pads 
with some
0000 steel wool before i started.

>
> 3. What type of flux are you using?  Don't know....for challenging 
> solder jobs, I recommend Kester 44 resin core solder...it will solder 
> just about anything.

Yep, that's what I've been using on this.

>
> 4. Finally, lets get down to what causes the pads to lift in the first 
> place...one of the primary causes, believe it or not, is water vapor.

Aha!  That could very well be it.  My workbench is out in the 
un-air-conditioned
garage.  I'm in Alabama and as you can imagine, it's rather humid this 
time of year.
I'm going to make it a point from now on to keep boards in work inside 
the house
in between soldering sessions.

> If there is enough moisture trapped between the copper and the 
> fiberglass, it will vaporize and when it does it will literally push 
> the copper right off...when I used to work for NASA, PC boards had to 
> go through a process they called thremal-vac, where the boards were 
> heated and subjected to a vacuum.

Interesting.  I've had the experience of seeing something go through 
thermal
vac before, but in this case (an experiment going to Mir) it was to 
take care of
outgassing, and it was done on the completed assembly.  I've never heard
of putting bare boards through thermal vac.  Sounds like an interesting 
idea,
though.  I wish I could get access to the thermal vac chamber at MSFC.

>
> Then again...you could change your name to Bullwinkle...or at the very 
> least, make sure Borris isn't trying to destroy you SDIY...

Look, Natasha!  Moose and soldering iron!