[Test-Equipment] UNSOLDERING

[Lee Ritta]

I have read the replies so far and I don't remember anyone mentioning,
Adding extra flux I have just done an advanced soldering course at college
And 50% of the course was about repairing and desoldering components, be
they SMD or thru holes devices. The basic step with all of them is to add
extra flux, you avoid dewetting, or poor wetting, and i.e. the solder flows
cleanly. I have used the Pace desoldering system and liked it that much I
bought one myself. I found that two things you need to consider, a correct
size tip and correct temperature, and again add extra flux.
I hope you find this useful.
Lee

-----Original Message-----
From: test-equipment-bounces at mailman.qth.net
[mailto:test-equipment-bounces at mailman.qth.net] On Behalf Of Tony Snider
Sent: Friday, 4 November 2005 8:50 PM
To: Test-Equipment at mailman.qth.net
Subject: [Test-Equipment] UNSOLDERING

after doing soldering and unsoldering for practically every day since I was
13 yrs old. and whether we are talking removing and reusing flatpacks with
solderwick, or double sided milspec coated boards. or whether we are talking
radio shack solder suckers or mega buck Pace stations, 

the MOST important thing of all is to ADD SOME FRESH SOLDER TO EACH JOINT
YOU WANT TO UNSOLDER.

this provides better heat transfer than tarnish and the joint will melt
instantly without heating up the board. also adding solder forces the joint
to swell and split the conformal coating on both sides of the board allowing
air to flow down the hole during extraction

the second thing to always remember is to rotate the desoldering tip around
the pin during extraction, this will move the pin away from the side of the
plate through and prevent it from rebonding to side.

for junk board removal one of the little butane rechargeable pencil torches
from radio shack works well, they come with some small attachments that
allow you to just heat one chip with out setting the whole board on fire
with a propane torch. then you just wack the board on a piece of wood and
your chip jumps out.

as much as I hate to admit it the 9.00 radio shack desoldering irons work
fantastic as long as you add solder and keep fresh tips on them.

Tony
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