Low-temp desoldering of SMT

[Chuck Guzis]

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.  

Cheers,
Chuck