Desoldering

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Mike6158
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Desoldering

Post by Mike6158 » Sun Feb 27, 2005 3:50 pm

Well... you know how you should read the instructions, reaad the instructions, and then solder in the component? I didn't do that. I soldered in an LED array when it was supposed to have an IC socket. The board is double sided with plated thru holes. I spent about an hour with solder wick and my iron removing solder but it's still "stuck". It won't wiggle at all. :( I can't get to the top side of the leads and I think that's where it's stuck. Any good ideas for how to get this thing out?
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."

jimandy
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Re: Desoldering

Post by jimandy » Sun Feb 27, 2005 3:57 pm

Ha Ha Ha Ha Ha,<p>Ooops, sorry about that. I only laugh because it has happened so many times to me, usually with the one-of-a-kind chip that I installed BACKWARDS!<p>My advice: Best not to destroy the traces or pads in further removal attempts, just bite the bullet, cut the leads off on the component side, kiss it goodbye, and install that socket.
"if it's not another it's one thing."

Mike6158
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Re: Desoldering

Post by Mike6158 » Sun Feb 27, 2005 4:15 pm

:D :D :D <p>I hear you... It will work as it's installed. They supplied a socket so that I could use the array as common cathode or common anode...<p>I soldered it very well... I can't get to the lead so snip them off if I wanted to... It's either live with it as is or desolder it...
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."

Enzo
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Re: Desoldering

Post by Enzo » Sun Feb 27, 2005 5:43 pm

Braid sucks because, well, it doesn't suck. Literally. You need at least one of the cock it and push the button deals. Ideally a desoldering station. Take it to an electronics repair shop of some kind and ask if they can extract the part without destroying the part for a nominal fee. My shop is hobbyist friendly, while not all are, so talk first to avoid that $50 shop minimum. And to ask if they even have a desoldering station.<p>Holes that are not coming clean will do better with plenty of fresh solder. Wet solder conducts heat better. Also, make sure when you heat it that you give it time to melt thoroughly all the way through to the top side. So sometimes it pays to add solder before removing it.<p>Braid takes two hands, so it is very hard to hold the iron and the braid AND wiggle the part. Wiggling helps insure the solder is removed all around the leg.

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philba
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Re: Desoldering

Post by philba » Sun Feb 27, 2005 8:19 pm

I'd just live with it unless you really want a socket. Every time you desolder/remove a component, you damage the PCB. maybe not beyond use but you only get so many shots at it. <p>Hot air would be your best bet. Turn the board over (component on the bottom), hit it with the streamof hot air and it should be easy to pull loose. It might just drop off. <p>Phil

gerty
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Re: Desoldering

Post by gerty » Sun Feb 27, 2005 8:39 pm

One thing that's always close by my bench is a solder sucker. I've tried the old Radio Shack one with a heating element and a squeeze bulb and didn't like it at all, didn't have the neccessary suction. The one I use now is a Soldapault(?)it's like Enzo says, cock it and press the button. Sometimes you have to add solder to get the tip close enough to molten solder to suck it out. And yes, there will be some stuff that'll be nearly impossible to get out no matter what you use..
Good luck.. :)

Mike6158
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Re: Desoldering

Post by Mike6158 » Mon Feb 28, 2005 5:30 am

I wish that I had a hot air station. I can't justify it for what I do though. At least I don't think that I can...<p>If it was a single sided board I would probably have more success with removing it. The plated thru-holes have a good hold on the part. I tried a "solder sucker" but it isn't budging. I need to be able to heat all of the pins.<p>Oh well... It's not a complete screw up. The board is a lab board for experimenting with PIC's. The part that I soldered in is an array of led's. The socket was included so that I could change the connection to the array from common cathode to common anode by changing some jumpers and installing the array in the opposite direction. No big deal if I can't do that.
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."

k7elp60
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Re: Desoldering

Post by k7elp60 » Mon Feb 28, 2005 6:21 am

Been there, done that too!!!.
I have a pair of side cutters with fairly small jaws and they are flush cutters. I can take a typical DIP that is soldered to the double sided board, clip the individual pins right next to the package on the top of the board. That is clip the pins one at a time. When they are all clipped I clip a pair of hemostats(the tool the doctors use to clamp blood vessels) on the individual pins, on at a time. Holding the hemostats in one hand heat that particular pin on the bottom of the board and gently pull the pin out.
I helps to clamp the board in a vise.
With patience(and some cuss words), it is possible to competely remove the part and the pins with no damage to the board. What usually causes damage is the direct pressure to the joint and then side movement.
Once the pins are removed from the holes the ones that still have excess solder in them can be filled with solder and then wicked out with the braid.
If you want to remove the component and don't care about the board, you have to heat all the pins at once. With a pair of pliers clamped to the ends of the part on the top of the board, A propane torch on low near the pins on the bottom
will heat all pins at once, pull the part from the board. Keep the part toss the the board.

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dacflyer
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Re: Desoldering

Post by dacflyer » Mon Feb 28, 2005 11:53 am

heres what i have done when in desperate situations. usually when in the salvaging situation for a certain part , here is what i'd do.<p>i get add solider to the pins..lots of it.. then with a really hot iron. i get all the solider molten , and then as its all molten, slowly wiggle the part...but do not force it to wiggle.
when all the pins (on one side)are hot..then the part should come loose..if possible work both rows of pin.. i have salvaged many parts this way.. wish you luck.

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haklesup
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Re: Desoldering

Post by haklesup » Mon Feb 28, 2005 12:44 pm

Aw, FLUX it<p>Seriously, use lots of liquid flux (paste is OK too). The solder will flow better, stick to the copper braid better and leave the pads a lot better shape than without. Don't just count on the flux core of your solder. Solderwick is useless unless it is soaked in the stuff.<p>I usually us a combination of the sucker and wick. If the pins are enough smaller than the hole it is easier because tight pins tend to stick to a cooled thru hole even with only a trace of solder left.

JKMADSCI
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Re: Desoldering

Post by JKMADSCI » Mon Feb 28, 2005 3:43 pm

Ive had great results with the rs sucker. I like it because you dont waste any time inbetween heat
and suction. In an emergency i use caned air if all else fails.

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jwax
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Re: Desoldering

Post by jwax » Mon Feb 28, 2005 6:30 pm

Cheaper than a hot air source is a solder pot. It's a heater and a small "pot", or bucket of solder that melts at temperature. If you slightly overfill it, the molten solder rises above the level of the pot, not overflowing due to surface tension, and touch your board to that puddle. All the joints that touch the molten solder get "reflowed" simultaneously, allowing the part to be pulled out. Do it quick, of course!

peter-f
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Re: Desoldering

Post by peter-f » Tue Mar 01, 2005 10:20 am

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by jwax:
Cheaper than a hot air source is a solder pot. It's a heater and a small "pot", or bucket of solder that melts at temperature. <p><hr></blockquote><p>What occured to me while doing a good bit of desoldering recently...
was a setup similar to jwax's desciption... <p>One hotplate, set to melt solder (+ 5-10 degrees), with a cold plate of aluminum nearby...<p>.. Heat your PCB- (reverse of wave soldering-- letting solder drip from the board)
.. pick up board with leather gloves
.. take heated board and slam flat on aluminum - solder-side down. - [may not be appropriate with multi-layer or very large boards]

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philba
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Re: Desoldering

Post by philba » Tue Mar 01, 2005 1:30 pm

For mass desoldering, I use a propane torch. Clamp the board upside down via one corner on the edge of a table (or other sacrificial surface) and then gently heat the board. Move the torch around a lot to prevent hot-spotting. When the solder starts to melt, I "pluck" the board (pull the corner up and let go). That knocks off a lot of parts. I use newspaper to catch the parts but the aluminum pan sounds like a good idea. For the big TH parts, I'll use pliers or a hemostat to gently tug at them. plastic connectors are tricky...<p>Phil<p>[ March 01, 2005: Message edited by: philba ]</p>

Mike6158
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Re: Desoldering

Post by Mike6158 » Tue Mar 01, 2005 1:33 pm

Lot's of good ideas but I'm afraid she's stuck. I can't risk ruining the entire board. I'll just lose some functionality...
"If the nucleus of a sodium atom were the size of a golf ball, the outermost electrons would lie 2 miles away. Atoms, like galaxies, are cathedrals of cavernous space. Matter is energy."

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