Desoldering advice please: Removing DIP IC's without damage

[Mad Professor]

Hi All.

I am looking for some help and advice with Desoldering / Removing DIP IC's from a PCB without damaging the PCB or the IC's.

I have a total of 7 DIP IC's with a total of 228pins.

My current soldering / desoldering tools include: cheap adjustable temperature soldering iron, standard De-Solder Pump (Solder Sucker), heated De-Solder Pump (Solder Sucker), desoldering wick, flux, etc.

I don't mind buying extra tools if it makes the job easier and less likely to damage the PCB and or IC's.

What would you recommend.

Thanks for your time.

Best Regards.

[wblock]

Which "heated desolder pump" do you have?  What is the budget for buying additional tools?

[Mad Professor]

The heated De-Solder Pump (Solder Sucker) looks like this:


At this point in time I don't really have a budget in mind, as I don't really know the costs of additional tools.

So I will just say as a starting point around the £100, but this is not a fixed price.

Thanks again for your time.

Best Regards.

[matherp]

It somewhat depends on whether they are soldered with lead or lead-free, single-sided or plate through. Lead-free and/or plate-through are  harder.

To be really safe I would use Chip-Quik to lower the melting point of the solder on all the pins and then invest in a proper temperature controlled hot-air gun. Set this to say 180C and play it over the legs until the Chip-Quik modified solder softens and then pull out the chips. I clear the holes using hot air to melt the solder and then a blast from a air-gun. Braid sometimes works to clear the holes but sometimes doesn't. Tapping the board on the bench when the solder is molten can also clear the holes.

[AlxDroidDev]

You might like Dave`s episode #542:



It's a desoldering gun station. He was able to desolder entire DIP ICs within a few seconds, with no damages to the pins or board. I liked the video so much, I now want to buy one of those. Apparently, it costs less than £100 in most places.

Neverthless, you can achieve good results with what you have. Just don't get the desoldering pump or soldering iron too hot and in the pins/pads for too long and all the ICs will survive perfectly. It's not very productive, ' though, but quite doable.

[mariush]

Stay away from tools like that heated desoldering pump (third post), they usually have very little suction and it takes time to bring the tip back to temperature between pins. Basically, it's very annoying.

Desoldering guns like the one in the post above work great, if you get the technique right. Basically, you may even have to add a bit of solder, then put the nozzle over the pin when it's hot enough, make some small circles with the tip around the pin to detach it from the walls of the hole and then suck the solder. Once you get the move, you desolder one pin in 2-3 seconds.
Just remember to not desolder pins sequencially, as you may overheat the chips or the board if you put heat in the same region, jump from side to side of the IC.

Unless you have high quality wick (with built in quality flux), stay away from it, it's more hassle than it's worth otherwise. I've bought cheap solder wick and hated it so much I almost gave up on using wick until I borrowed a quality (expensive) one with good flux in it. Makes huge difference.

What I would do is apply a bit of liquid flux over the pins, then optionally (if I feel it's needed, if there's very little solder in the first place) add a bit of solder to each pin (doesn't matter if it's lead free or not), then go with the iron and heat the pins and use a regular quality solder sucker to suck the solder.  I have an aluminum one with a long spring, which makes a lot of suction.... and if you want you can improve it by adding a tiny bit of silicone tube over the existing tip, the silicon will tolerate the heat well and last a long time.

[ConKbot]

+1 to chip-quik if you dont want to damage either the board or the ICs, with that many chips, thats the best way to slope the odds in your favor.  If youre board has generously sized plated though holes (or is single sided) then you can probably do it with wick and suckers, etc. But if it is even somewhat tight, youre going to get a pin that doesnt want to clear out fully etc.   If you absolutely have to save the board, cut the pins on the IC, if you absolutely have to save the IC, cut the board, if you need both, things just got a bit harder :p

[KJDS]

Nothing makes life easier than a decent Pace desoldering tool, but they are expensive. Even then you'll sometimes need to use wick as a supplement on stubborn holes, especially if some leads were initially bent to hold the chip in place prior to soldering.

[wblock]

For quick and easy, I'd go with a vacuum desolder tool first.  Hot air can be very effective, too.  Chip Quik works, but is slower, messier, and fiddlier.

Whichever method is chosen, find some scrap boards and practice first.

[bookaboo]

I've tried loads of heated desolder tools including the one in Dave's video linked above. I've yet to find a better solution than hand desolder pump then take the rest off with wick.

[Aodhan145]

You can use desolder braid to remove the solder then just pull on the chip with a set of pliers.

[fivefish]

Hakko 808
like soldering in reverse....

[bookaboo]

You can use desolder braid to remove the solder then just pull on the chip with a set of pliers.

I find it best if you can remove enough solder that you need very little mechanical force, often the pin just needs "freed" to the middle of the hole after all the solder is removed.

[KL27x]

Having recently desoldered a pretty decent batch of through parts done with lead-free solder, I can put in two cents on a solder sucker. For years, I often added a little flux and/or some low melt-point bismuth solder to the joints prior to desoldering. But after some recent experimentation, I changed my algorhythm. If there's enough of a bead to give good contact to the iron, I would leave it alone. With this lead free stuff, it may very well LOOK like the bead isn't completely flowed, even when it's completely melted. With some experimentation, you can find out how long it takes your iron to melt the joint. Even though you can't really see it, and the joint looks cold on the other side, I find it clears just as easily. Any added solder will add fresh flux, and flux is what clogs up the tool. Flux plus solder dust = cement. A good sucker will clear the holes faster and with much less maintenance if you can clear them as is.

If you don't melt the entire bead, you will screw it up and the hole won't clear. Then you will probably have to add some solder to get a good thermal contact. And you may think it will save time/effort to flux up the joints, because you can see the joint reflow. But it you have a big pile of parts to do, you can figure out what temp and how long to hold the iron to breeze through the pile without stopping to clean the sucker, even without this visual indicator.

There is a big difference between a good solder sucker and a bad one. If you want a good one, I suggest anything by Edsyn, or one of the many clones of their original Soldapult.

[wblock]

Hakko 808
like soldering in reverse....

Hakko 472D here, but pretty much, yes .  Yesterday I replaced a soldered-in flat flex cable, two 8-pin SIP arrangements.  It took longer to heat up the desoldering station (three minutes) than to actually do the unsoldering.  Worth the time, though.  The last time I used an iron to heat and pull header pins out, I tore off some pads without even noticing.

It does vary some from board to board.  More layers make it tougher, and some old boards have particularly sludgy lead-free solder that needs flux or more solder or both.

[GreyWoolfe]

You might like Dave`s episode #542:



It's a desoldering gun station. He was able to desolder entire DIP ICs within a few seconds, with no damages to the pins or board. I liked the video so much, I now want to buy one of those. Apparently, it costs less than £100 in most places.

Neverthless, you can achieve good results with what you have. Just don't get the desoldering pump or soldering iron too hot and in the pins/pads for too long and all the ICs will survive perfectly. It's not very productive, ' though, but quite doable.

+1, I have this and it works well.  If you decide to get one, I would suggest you practice with it on a throwaway board to get the feel for using it.  I lifted pads on the practice board until I got the hang of using it.  Make sure you keep it clean.

[KL27x]

Another tip: if you have an awkward board that won't sit still and can't be easily clamped in a vice, get your glue gun ready. Temporarily glue the boards to you bench and use alcohol to remove the glue, after.

[Mad Professor]

Thank you for your replies.

The PCB in question is the main control / interface board from a CNC Lathe,  "LCB3 (c) 1990 GSM-Syntel LTD".

I am in the process of upgrading the Lathe with more modern hardware and software, but it seems that GSM-Syntel LTD have long been out of business.

I will upload some pictures of the PCB in the morning.

Thanks again.

Best Regards.

[alsetalokin4017]

You can use desolder braid to remove the solder then just pull on the chip with a set of pliers.

I find it best if you can remove enough solder that you need very little mechanical force, often the pin just needs "freed" to the middle of the hole after all the solder is removed.

Yes, this.

I remove a lot of parts from old PCBs, just pulled a couple of DIP ICs off one yesterday in fact. I am using just solder braid and flux pen more and more these days, although I do have a sucker as well, and some ChipQuick in the toolbox for many-pad SMDs,as well as a hot air station. But for through-hole DIPs, I take some braid, run the flux pen on it from both sides, and then use the iron, slightly hotter than for actual soldering, to run the braid slowly along the chip's pins, moving to fresh braid for each pin. It's amazing how the solder just runs up into the braid. Often just one application will remove all the solder from a plated through-hole and pin. Then I sometimes use a small screwdriver to push the pin to the middle of the hole, as suggested above, to break that last little bit of adhesion. The screwdriver will also be used as a "prybar" to raise up the chip and free it from the board. Sometimes it will free first on one side or end; a bit more heating with the iron will free up the remaining pins. Then a careful straightening with the fine-tipped pliers to get the pins back into shape. Clamping the chip in the Panavise and then hitting the pins with iron+braid+flux again to remove ugly residual solder is a last step.

Sometimes it helps to add some lead-tin solder first, which seems to help flow the lead-free junk and make it easier to wick or pump up.

I do suggest practising on unimportant chips first -- I've had a _lot_ of practice myself.
But then I mostly deal with 20 pins/chip and under.

For big components like flyback transformers off TV/CRT monitor boards,  I use a monster heat gun of the type used for removing paint, but in those cases I care not about the board itself or adjacent components.

My braid, flux pen and sucker:

[KL27x]

^That sucker is the reason you use braid. I went through two of those things. Used them for many years before finding out how crappy they are. Use a real sucker, don't add flux, and the part will not need any prying. If it doesn't fall out by itself, just pulling on it with your fingers will be enough to get it out! And you will get it done, faster.

[alsetalokin4017]

^That sucker is the reason you use braid. I went through two of those things. Used them for many years before finding out how crappy they are. Use a real sucker, don't add flux, and the part will not need any prying. If it doesn't fall out by itself, just pulling on it with your fingers will be enough to get it out! And you will get it done, faster.

Well, everybody's got an opinion, I guess. And while you were expressing yours, I made a video demonstration using the braid+flux, removing a 28 pin chip from an old board. Perhaps it took about as long as it would have taken you with your Real Sucker -- and all the solder wound up in the braid, easy to cut off and dispose of, without having to take something apart, clean it and reassemble it. Of course the solder braid costs money that you aren't spending when using your Real Sucker -- I used about 18 cents worth to remove the chip.  I'm guessing I probably would be able to remove a couple hundred 28-pin chips for the cost of a Real Sucker.   

I'll be posting the video to YouTube as soon as it finishes processing.

[KJDS]

The other way I have that works well, a set of metcal tweezers with big bits in either side, can comfortably heat every pin of a 16 pin DIP at once. It's worth adding some fresh leaded solder to ensure a good contact all round. Contact for three seconds and pull it out gently but firmly. You'll need to clean the board up afterwards.

[RobertHolcombe]

Another vote for the Hakko 808 or FR-300. The 808 has been discontinued, however if you had the option to buy either one brand new I can definitely recommend the FR-300 being worth the additional cost. The form factor (no base unit) makes them very compact and portable - the FR-300 is significantly more comfortable to use. I would only recommend other units w/ base stations if ergonomics was a serious consideration i.e. when working at the same bench 40+ hours a week and performing mass desoldering.

[tooki]

Just a tip on solder wick: the MG Chemicals wick (as shown in the photo above) is AWESOME. It uses much finer wires than any other wick I've tried, which turns out to create superior thermal transfer and capillary action. The fact that it's rather cheap on Amazon.com is just icing on the cake.

[alsetalokin4017]

Just a tip on solder wick: the MG Chemicals wick (as shown in the photo above) is AWESOME. It uses much finer wires than any other wick I've tried, which turns out to create superior thermal transfer and capillary action. The fact that it's rather cheap on Amazon.com is just icing on the cake.

Yep, and with some added flux from the flux pen it works even better.



(Hey, it's not a "Dave" video or a Rossmann video, but it is what it is.)