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Mcgyver
09-05-2005, 10:16 PM
wanting to take a couple components off an old circuit board, i was messing with those braided cooper rolls to de-solder when I thoguht why no use the same principal as the expensive solder vacuums. Out to the shop, turn on the air compressor and grab the safety glasses. Little bit of heat to the solder, shot of air directed at the molten solder (pointing away from hand holding the solder iron of course), move onto next pin. In minute or less, component, no matter how many pins, is easily lifted out.

It does make a mess of the back of the board so not for stuff you want to keep, but good for salvage work.

AZSORT
09-06-2005, 12:46 AM
Rad Shack sells a desolder iron for about $10 that uses a squeeze bulb to do the sucking and is real handy and doesn't leave a mess. The tips burn out pretty fast so don't leave it plugged in.

Weston Bye
09-06-2005, 06:35 AM
For desoldering surface mount components, I found that a heat gun and tweezers work great. This is the heat gun I use.

http://www.newark.com/product-details/text/CD121/Images/Web1/35F3074-30.jpg

There are others as well. Use the pinpoint tip to focus the heat. I found hot air to work better than an iron, and with a little care, the board is undamaged.

Wes

BillH
09-06-2005, 11:02 AM
A slightly more destructive way if your not careful, take a propane torch, heat up the whole board to melt the solder, then slam the board on something, pick up all your components.. Hmm, you know, that heat gun is sounding better!

Evan
09-06-2005, 11:09 AM
I have used the torch and whack method too. It works fine but you do need to watch out for flying solder.

For more carefull desoldering solder wick works well if you have the right type. It is sold both unfluxed and fluxed. The unfluxed solder wick isn't worth buying. The fluxed wick together with a solder puller (vacuum gun) makes easy work of removing components.

Paul Alciatore
09-06-2005, 11:47 AM
I've been at it (desoldering) a long time. I've tried the bulb type vacuum irons, a very expensive iron with a built in vacuum pump (it's on my bench right now and I rarely use it), the braid, etc. The braid is hit or miss. Some times it works very well and others nothing. The bulb type iroms require manual operation of the bulb and that frequently takes the tip of the iron off the pad when you release it. And they do not have a strong vacuum so they are marginal at best. The expensive iron with the built in pump is also weak and marginal at best: a tank would help.

The best tool I have found is the solder vacuum. They consist of a plastic cylinder with a piston and spring. You cock it by depressing the plunger and it clicks in place. You heat the pad or joint and place the tip on it and press the trigger. It instantly applies a large vacuum that usually clears the hole the first time. Since all you do is press a trigger, it is easy to keep the tip on the pad. I like the big blue ones.

If you are going to throw tne part away and replace it, it is often best to cut the leads to remove it first. That way you just have to remove the bit of wire in the hole with the solder vacuum.

If the board is going to be reused, I would not use the compressed air as it will send drops of solder everywhere and they can be hard to see. A short under a chip would be very hard to find and fix.

Paul A.

J Tiers
09-06-2005, 12:04 PM
I'll second the Soldapullt...the blue sucker.... The most powerful are the ones with the long rod out the top.

The competitors have way less "suck", like Paladin.

One problem they most all have is that they will leave a small spray of solder around teh hole. That is mostly if there is too much old solder inside the sucker, but can happen anytime. The wick does not have that problem.

Another issue is that they tend to skitter a bit as the piston flies up, forcing you to try again.

Also, with plated through holes, using most any method, if you try to unsolder the IC one pin at a time without clipping, often the pin lays against the wall of the hole, and there is a bit of solder that won't wick out or pull out up teh side of the pin.

If you then try to pull the IC out, you may mess up the plated through "barrel" in the hole. Same if you heat it too much, too often, etc.

Clipping allows you to suck/pull the leads out from above, so that any clipped shoulders of the leads come out OK.

Since I made a simple heated block that ments the solder on all the leads at once, I have had far less trouble and damage when repairing. The whole IC comes out in less toime, with less heating than doing teh holes individually. Clearing the holes takes less time because the lead isn't in there obstructing things. Total heating time is less.

Similar items are available commercially, but we all have shops, and a bit of brass plus some time is all you need.

ibewgypsie
09-06-2005, 12:08 PM
I use the solder bulb.

Put it onto the part pin, squeeze in and out slightly and when you see the solder becoming molten pull back squeeze bulb and put tip on pin and release bulb.. it should be loose.

Putting a part back in? Take the same solder bulb load the tip with solder, heat pin and squeeze bulb pushing solder around pin/hole.

Most times the factory can't tell you replaced a part. (*don't ask, don't tell)

David

Weston Bye
09-06-2005, 12:14 PM
[QUOTE]Originally posted by J Tiers:
[B]I'll second the Soldapullt...the blue sucker.... The most powerful are the ones with the long rod out the top.

These are very good. My first preference for thru-hole work.

The early ones just had a big knob on the end of the rod that jumped out when you pulled the trigger, hitting you in the face if you were not careful. Happened to me.

Wes

Paul Alciatore
09-06-2005, 05:22 PM
<font face="Verdana, Arial" size="2">Originally posted by J Tiers:
I'll second the Soldapullt...

One problem they most all have is that they will leave a small spray of solder around teh hole. That is mostly if there is too much old solder inside the sucker, but can happen anytime. The wick does not have that problem.

Another issue is that they tend to skitter a bit as the piston flies up, forcing you to try again.

Also, with plated through holes, using most any method, if you try to unsolder the IC one pin at a time without clipping, often the pin lays against the wall of the hole, and there is a bit of solder that won't wick out or pull out up teh side of the pin.

If you then try to pull the IC out, you may mess up the plated through "barrel" in the hole. Same if you heat it too much, too often, etc.

Clipping allows you to suck/pull the leads out from above, so that any clipped shoulders of the leads come out OK.
.....
</font>

Yep, that's the name.

The spray of solder around the hole is easily removed by quickly running the tip of the soldering iron around area after removing the part. It only takes a second.

Yes, they move a bit but not near as easily as the bulb types.

On the pins on the side of the hole thing, the jerk of the solder tool is often enough to dislodge it. When that does not happen, you can use a small (&lt; 1/8") screwdriver to push it sideways while reheating the pad. That will dislodge it. If you are trying to save the chip, you often have to go around and do that to all the pins. Push first, then heat and push if needed.

If the board is to be reused, never apply more than moderate force. The copper traces will come off the board with surprising ease. Be gentle.

Boy, this thread is becomming a great de-soldering tutorial.

Another quick tip. Often it is desirable to add a small amount of solder to a joint you are trying to desolder. This helps transfer the heat of the iron to the joint and melt it quickly and completely.

Paul A.

[This message has been edited by Paul Alciatore (edited 09-06-2005).]

3 Phase Lightbulb
09-06-2005, 08:39 PM
I made a small video tonight using my desoldering station. I'm a little rusty as I haven't used it in awhile. I've populated entire motherboards with this unit. I use it to both solder/desolder all surface mount components, ball grid arrays, etc. It's a digitally controlled hot air station with about 32 different nozzels for different package types:

Low quality video (2mb):

http://www.bbssystem.com/desolder/desolder.wmv

High quality video (12mb):

http://www.bbssystem.com/desolder/desolder_high.wmv

-Adrian

JRouche
09-06-2005, 09:33 PM
I have an old Pace solder-desolder station that works just fine for me.

While in the service I used that super sucking blue tube (SOLDAPULL) but I still like the controllability of the station. JRouche

Mcgyver
09-06-2005, 09:41 PM
Adrian, thx for the video, for the unitiated can you describe what its doing? is it vacuuming up the solder? if so how does it apply the heat?

3 Phase Lightbulb
09-06-2005, 09:47 PM
Mcgyver, It's blowing super heated air and only locally heating up the pads to the point that it reflows the solder. I have a bunch of different nozzels for different footprints.

I didn't bother to practice before making that video. I'll make another one in a few minutes that really shows you how fast and efficient it works.. You'll notice as soon as I bring the nozzle close enough, the chips just start floating. I just need to practice for a few minutes and I'll create another video.

-Adrian

3 Phase Lightbulb
09-06-2005, 10:07 PM
I didn't really practice, but I tried again removing a row of line drivers. I'm still quite clumbsy but after working with it for a little bit, I can just pull components by just looking at them:

Low Quality (1mb):

http://www.bbssystem.com/desolder/desolder_row.wmv

High Quality (5.6mb):

http://www.bbssystem.com/desolder/desolder_row_high.wmv

-Adrian