Re: de-soldering IC's

In article <ZXYPf.18014$vC4.4770@clgrps12>,
"Dave" <dspear99ca@xxxxxxxxxxxxxxxx> wrote:

"Smitty Two" <prestwhich@xxxxxxxxxxxxx> wrote in message
news:prestwhich-09DCBA.22170008032006@xxxxxxxxxxxxxxxxxxxx

Get some liquid flux !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Really !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


I never solder without it, and you should never, ever, ever, try to
desolder without it, unless irritation and frustration and destroyed
parts and boards are interesting to you.


All right, already. I went and got some godd#mn flux about a year ago after
reading one of your posts. Still not sure exactly when to use it or how
much to use... seems to leave a bit of a mess on my board when the job is
done, i.e. doesn't come off with isopropanol and a Q-tip.

You only need a drop. I use a 2 oz. squeeze bottle with a 0.010" ID
needle. A larger diameter needle will make a mess. But, whatever, the
alcohol should clean it up OK. I pay about $30 for 5 gallons of alcohol,
and $4.00 for 1000 cotton swabs, so I don't worry too much about the
cost of using several swabs. We use 99% isopropyl. The drugstore rubbing
alcohol may not be as good.


METHOD 1: (preferred)

----------------------------


Nope. No fancy desoldering station for me, one more piece of electronic
gear in my workshop and I'll be in divorce court for sure. I like the $5
desoldering braid. I may learn to like my $15 desoldering pump if I figure
out the technique.

ALTERNATE method for those who can't justify owning a professional
sucker:

Cut the pins, as others suggested. Now, get out your liquid flux. You do
have some, right? You say you solder, and you don't have liquid flux?
That's absurd. Go get some.

Put flux on the top and bottom of each pin.

Now, hold the board over the edge of the table with one hand, so that
both the top of the board and the part of the hand used for karate chops
face down to the table.

Melt the solder for at least three seconds. The pin will usually fall
out by then, but regardless of whether or not it falls, pull the
soldering iron away and *immediately* karate chop that table! This
hurts some, but the reward is worth it.


I'm not 100% sure I understand your technique but hey, it's worth a try. I
generally work at my bench; I may need some sort of protective glove to make
it shake given it weighs >150kg and is lag-bolted into a concrete wall. Or
maybe I could try a card table.

You're just trying to knock the pin and the molten solder out of the
hole. Think of whacking the board on the table while the solder is
molten. But, instead of that, which might damage something on the board,
I hold the board firmly in hand and whack my hand on the table. Hand
acts as a shock absorber. (Obviously, if the board in question is still
bolted to the inside of a TV cabinet, this technique isn't applicable.)

It's true that new solder is flux cored, but when you're trying to
desolder, whether with a plunger pump or a machine or braid, the trouble
is, there's no flux left in the soldered joint. Flux is what makes the
solder flow. No flux, no flow. That's why some advocate adding more
solder, but what they're really doing is adding a little fresh flux. Far
better to add what's actually needed, some fresh flux. For the solder
braid enthusiasts, liquid flux will improve your results tenfold at
least.



The pin, if it was still there, and the solder, will depart the board,
leaving a nice, clean, wide open hole. And a nice solder splash on your
table. Repeat as needed. After fourteen to sixteen pins, your hand may
hurt some, but your heart will sing. You must be courageous! Do not
soften up as you go along! Stay vigorous.

Now go get some liquid flux before you embarrass yourself.

I used some flux yesterday. It worked. It worked very well. It worked so
well I had to clean up the mess on the other side of my board! Part of my
bungling component removal technique is to destroy at least one metal pad
(metal circle on PCB with no trace attached). If one is trying to solder in
a new component, it's tough to get the solder to flow to the other side of
the board without the metal pad... the solder tends to want accumulate on my
iron instead of flowing onto the heated component lead. Ahh, enter the
flux. I used it on two of my IC pins and yowza! Solder went right through
the hole and dripped off the pin on the other side before I realized it!



Thanks for the advice and the entertaining manner in which it was delivered.

Dave
.

Relevant Pages

  • Re: de-soldering ICs
    ... Get some liquid flux!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ... I never solder without it, and you should never, ever, ever, try to ... No fancy desoldering station for me, ... Cut the pins, as others suggested. ...
    (sci.electronics.repair)
  • Re: newbie solder question
    ... > liquid--is to 'activate' old desoldering braid. ... > the end into the flux between uses. ... know a hell of a lot about troubleshooting, but I know how to solder. ...
    (sci.electronics.repair)
  • Re: de-soldering ICs
    ... my aging desoldering braid. ... So I heat up my iron, apply the braid, ZOOP, up comes the solder into the ... Get some liquid flux!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ... top and the bottom of each pin. ...
    (sci.electronics.repair)
  • Re: New way to mess up soldering copper pipe!
    ... plumber under my house for a few days now, ... First we suspected the flux had become ... Harbor Freight to apply the flux and he likes to continue to brush on ... Of course you can't solder joints when they're filled with water, ...
    (rec.crafts.metalworking)
  • Re: Soldering a tractor radiator - UPDATE
    ... I had also thought it might be safer to leave the radiator partially filled to protect it from heat, but I think the poor access for cleaning and doing the actual soldering mean that it isn't a great plan. ... so I think I'm going to need to get the solder off. ... Then there's the question of flux. ... The previous repair of oversoldering will come off with your flux brush a 1/2in paint brush will do. ...
    (rec.crafts.metalworking)