17 Nov
2006
17 Nov
'06
4:51 p.m.
Of course the thing to do is to not need to use a
pulled part in the
first place, but sometimes that is not really an option with rare
chips. Just keep in mind that a solder pulled chip is a weaker device
than one factory new, and that latent failures lie within.
While heating a chip (e.g. by soldering/desoldering it) will weaken it, I
am not sure the effect is particularly noticeable. I've not noticed that
the chips I've desolderd/resoldered are especially likely to fail (e.g.
if I've removed a few chips from a board for testing, then resoldered
them, future failures on that board may well not involve any of those
chips). I've done it with SMD stuff too -- the manufacturers tell you not
to, but I have never had any problems from so soing. If I was making
stuff where a failure could cause significant loss or injury then I'd
bahave rather differently of course.
And given the choice between a backup of the program in a chip (e.g. on
my PC) and a possibly weaker chip (that is, I've desoldered it to copy it
[1]) and not weakening the chip but no backup (so when it fails I am
really stucK), I'll pick the former every time.
[1] Of course I don't resolder it. I put in a turned-pin socket.
Always. We can debate the reliabilty of sockets ad nauseam, but none of
the classics I own are in 'mission critical' -- if I get bad contacts at
a socket I can rasily reseat the chip without any real problems.
-tony