"John-Del" wrote in message
...
On Tuesday, February 9, 2016 at 6:26:21 AM UTC-5, Cursitor Doom wrote:
Hi all,

Anyone got any tips on how to avoid the unpleasant situation where you
try to de-solder a part on an elderly board and end up removing more than
just component leads? Most of the stuff I work on is at *least* 25 years
old and things start to get fragile.

thanks

Preheat the board before desoldering and apply some liquid flux. Make
sure to use *enough* heat as too low is just as bad as too much. You want
to reduce the time it takes to finish the process more than anything.

I'd add to that; make sure the end of the lead isn't bent so it struggles
when you try to pull it out.

Although its my preferred method, I'm reluctant to recommend a piston type
solder sucker because the recoil can knock pads off if you're not careful.
Conversely; solder wick has to be kept hot while you pull it away, or the
pad/track comes with it - which doesn't really help with keeping the heating
to the shortest time possible.

Sometimes you have to remove the solder to inspect the end of the lead, and
straighten it if required. All I can suggest is; use the method you're most
comfortable with.

A single sided board is dead easy if you remove the solder, through hole
takes a little more effort. Some manufacturers do sucker irons where the tip
is hollow and has a receptacle for the waste solder, the expensive ones with
an electric pump or the cheaper type with a rubber bulb next to the handle.
It almost never removes *ALL* the solder from a through hole, but you can
usually wiggle the lead free with pointy nose pliers.

In most cases more solder and the flux that comes with it is added to
improve heat flow - in the case of RoHS solder, adding some 60/40 lowers the
melting temperature.