Low-temp desoldering of SMT
cclist at sydex.com
Sat May 3 21:28:23 CDT 2008
You've probably all heard about Chip-Quik--a low-temp soldering alloy
used to desolder SMT at about 150C. Today, I took a scrap board and
decided to try my own version.
Normally, I keep a fair amount of Wood's metal around for bending
thinwall brass tube (filling a tube with the stuff keeps it from
collapsing while bending). WM melts at about 158F (70C) and I
wondered if the considerably cheaper Wood's metal would do the job
that Quik-Chip is sold for.
It does--I just removed a TSOP28 package using nothing more than a
couple of scraps of WM and a 90W PAR38 spotlight to heat the PCB. I
moved the WM around the chip leads a bit and then grabbed the chip
with a bit of silicone putty on the end of a fingerip. The chip came
right up. A little flux might have speeded things up a bit, but I
didn't bother with it. Cleanup was easy--shake the excess metal off
the board, wipe down the pads. I'd probably clean the pads a bit
more if I wanted to resolder a chip there.
Thought folks might like to know. WM is marketed under several trade
names, such as Cerrobend.
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