I've got a display module that I designed and built that consists of two
double-sided PCB's sandwitched together. One PCB has 35 5x7 LED modules
on it, the other PCB has the driver circuitry. The former PCB is
entierly through hole while the latter is almost entierly fine pitch
surface mount, soldered using a toaster oven. The connection between the
two boards is made by in-line strip connectors, soldered to both boards.
72 individual pins in total go between the boards.

In short, the gap between the boards is about 0.100" and getting them
apart is going to be a real pain. I did carefully check that none of the
protruding pins from the through-hole components are shorting anything,
that is not an issue. I really need things to be compact in this
application.

The whole assembly works perfectly except... Somewhere on the LED board
there are two shorts, between two pairs of column lines to the LEDs. I'm
pretty certain that they are caused by tiny solder bridges, the layout
of the boards was very tight in some areas.

Any clever tricks you guys can think of to fix this, short of taking
everything apart? I'm half inclined to try simply running everything
through the reflow oven again, but the LED modules would probably melt. 

And if I am going to take things apart, how the heck do you reliably
desolder pins from through-hole plated circuit boards? I've always found
the solder sticks too well for solder-wick to remove it. Using those
solder suckers is a nice theory, but the joints cool before I can
position them and release. Unfortunately if I manage to damage any of
the pins, I've really got to then take off the led modules to solder in
new pins as the joints are obscured...

Somehow, after looking at how compact Cray's were built, I think they
had better pre-assembly testing than I did!

-- 
pete@petertodd.ca http://www.petertodd.ca
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