Desoldering tips for through hole components - Page 1
Forum section: electronics / beginners

author: Skippy
author_rank: Contributor
timestamp: October 29, 2012, 03:00:32 pm
content: I'm frequently having trouble desoldering through-hole components, especially from double sided boards, and I was wondering if someone can help.The tools I have available to me are a soldering iron, leadfree multicore solder, solder wick and a solder sucker. I've also got some chipquik. I don't really want to spend a ton of money on a desoldering gun.The problem I have is that I can in general melt the solder and get the component out. The thing I really struggle to do is get the hole cleaned out- so I can see all the way through and is unblocked, rather than being blocked with solder. It's making it difficult to solder replacement parts in.My current technique is to add solder using the iron, then see if I can remove the solder by heating the whole lump of solder, quickly removing the iron, sucking with the sucker hopefully before it freezes, and repeating. Some holes I can never seem to clear this way. This is easier if I add some Chipquik to the mix as it stays molten longer, but this doesn't seem like the "right way" of doing things. I'm contemplating getting some leaded solder too for a similar purpose.Has anyone got any advice.

author: SeanB
author_rank: Super Contributor
timestamp: October 29, 2012, 03:18:38 pm
content: Stainless steel crochet needles will go through the hole and will not stick to the solder.

author: grumpydoc
author_rank: Super Contributor
timestamp: October 29, 2012, 04:15:43 pm
content: A vacuum desoldering iron makes this much easier.

author: StubbornGreek
author_rank: Frequent Contributor
timestamp: October 29, 2012, 04:51:01 pm
content: I haven't found the (mechanical) solder sucker effective after the component is removed. Instead, flood with a little fresh solder and use the wick. I have a Hakko 808 sitting on my bench but I don't power it up unless I'm doing lots of desoldering - the wick works fine for most things. One important note is to use wick that's already treated with flux (or add your own). I've use some braided wicks that weren't treated and I may as well have been using nothing at all - completely useless and frustrating.

author: Skippy
author_rank: Contributor
timestamp: October 29, 2012, 06:36:16 pm
content: Quote from: StubbornGreek on October 29, 2012, 04:51:01 pmWick never gets rid of it all for me, I'm always left with some in the hole.

author: Skippy
author_rank: Contributor
timestamp: October 29, 2012, 06:37:59 pm
content: Oh and I'm trying to desolder industrial soldered boards. I can always wick away the solder I add. I'm spending my life adding solder, then taking the solder I've just added away again.

author: AndyC_772
author_rank: Super Contributor
timestamp: October 29, 2012, 06:55:55 pm
content: It sounds like you may simply not be getting enough heat into the joint. Do you have a bigger and/or hotter soldering tip available?

author: ptricks
author_rank: Frequent Contributor
timestamp: October 29, 2012, 08:42:43 pm
content: Add flux not solder to make the solder fluid enough that it will suck out easily. A desoldering iron with the bulb vacuum attachment really does help with doing lots of through hole work and they don't cost over $20.Also don't forget to put an alligator clip or some form of heatsink on parts you are removing as well a clamp on the board itself can help remove excess heat and prevent board damage.

author: Smokey
author_rank: Super Contributor
timestamp: October 29, 2012, 08:43:33 pm
content: This kind of thing happens because of poor thermal isolation of big pads from the surrounding thermal mass. That's why there are those thermal spokes around some pads. It's so you can heat up the pad and not have the big copper pour/ground plane it's connected to suck out all the heat. Sometimes you can't put the spokes in there because it reduces the copper area too much like in high current applications or something. I've had to do boards with multiple layers of pours, inner and outer, directly connected to through-hole pads. When the boards are professionally assembled it's not usually a problem since they can do wave soldering which heats up the whole board. But when you are hand soldering/reworking these it becomes near impossible. It's not so much a matter of having a hot enough soldering iron tip because the amount of heat required to heat up the whole pour around the pad is huge. Depending on the size of the connected thermal mass, having a vacuum desoldering tool might not help either. A lot of times the thermal mass you need to heat up is going to be on the other side of the board from the solder joint you can get to and even under things like big caps. In that case you are trying to heat up a pour or something through the board with only the pin of the part and the little copper in the barrel of the hole as a thermal conduction path. Good luck.The only sure fire way to rework a board in this case is to preheat the entire board around the pad. They make fixtures that hold your boards and have heating elements under them. You can also use a hot air rework station, but that gets tedious as you have to sit there for a while moving the air around the section you are reworking.If you sit there with a normal soldering iron on the pad for long enough, you will EVENTUALLY heat everything up enough that all the solder will suck out with a normal solder sucker, but you better have something to keep you entertained while you wait.

author: ciccio
author_rank: Frequent Contributor
timestamp: October 29, 2012, 09:03:26 pm
content: Quote from: Skippy on October 29, 2012, 03:00:32 pmYou should not remove the iron before putting the sucker on the joint. Doing this you let the joint cool down before vacuum is applied.The sucker has an heat resistant nozzle that can stand the heat of the soldering iron tip.You should put the iron's tip on the joint, and apply the sucker's nozzle on the tipandthe joint, then operate the sucker's pumpwithoutremoving the iron from the joint.See this youtube video.Other tips:1) use more heat than you will use for soldering2) apply some solder or some flux to the joint before desoldering, and "redo" the solder joint: solder will be more esaly to fluw away.Best regards

author: 6502nop
author_rank: Regular Contributor
timestamp: October 29, 2012, 11:04:42 pm
content: Got $13? ($15 if you get an extra tip...)http://www.radioshack.com/product/index.jsp?productId=2062731&filterName=Type&filterValue=DesolderingTip: Let this thing warm up for about 20 minutes before using. Tap a bit of fresh solder on the rim of the tip before touching to joint. Press bulb BEFORE touching to joint, then when you see the solder melt, release bulb. Takes a couple of tries, but you learn quickly.nop

author: Psi
author_rank: Super Contributor
timestamp: October 29, 2012, 11:30:55 pm
content: - When using the solder sucker add more solder first. Also give it a few seconds to heat the joint properly.Don't try to get the solder sucker tight over the hole, it works better to have it at a little angle where it can pull in air, the fast moving air will take the solder with it.- Always keep your solder sucker clean, they don't work well once they get full of solder. Also the oil dries out.To clean it take it apart and remove all the solder from inside then apply some oil to the rubber seals and put it back together.It will move MUCH faster after a good clean and oil. (and work much better)- When removing a 2 leg component if you can get one leg free you can just apply the iron to the other hole and pull it out. No need to remove solder from both holes until after you get it out. Sometimes one of them is the ground plane and very hard to clean when the component is still there.- If you can get a wide iron tip you can often heat up all pads at once and just pull out the component. Its much easier to clean the holes once the component is out.

author: grenert
author_rank: Frequent Contributor
timestamp: October 29, 2012, 11:41:09 pm
content: If you're doing desoldering with any kind of regularity, I highly recommend an Edsyn Soldapult:http://www.edsyn.com/index.php?Mode=piw&pn=DS017I used to have the same problem with some solder still holding the lead to the board. The vacuum on the Soldapult draws just about everything from the hole, leaving the lead floating freely in the middle.I'm also a big fan of quality solder wick (Chemtronics, Easy Braid) if you still need to get that last bit out. Like others have said, some extra flux is often beneficial.

author: Jimmy the Squid
author_rank: Regular Contributor
timestamp: October 30, 2012, 12:02:15 am
content: Here's a video from JumperOne that demonstrates the use of compressed air as a means to blow the solder out. Seemed to make quick work of the components, but there are likely to be environmental concerns from the atomized lead.I liked his youtube videos, but he hasn't posted in a while.

author: nukie
author_rank: Frequent Contributor
timestamp: October 30, 2012, 03:04:13 am
content: Lead doesn't get atomized at normal soldering temperature.

author: mariush
author_rank: Super Contributor
timestamp: October 30, 2012, 03:23:12 am
content: Or you could use something like this:Though I can see it would be hard to use it for desoldering a single DIP chip on a large board. There are however similar designs which have only about 1-2 cm in diameter openings at the top and they also have some sort of pump that squirts the solder towards the board in a small area.

author: Psi
author_rank: Super Contributor
timestamp: October 30, 2012, 04:36:34 am
content: Soldering pots scare me a little, not just because they could fall over but because they heat up everything, the PCB and the components.Seems a bit risky if you want to reuse stuff.

author: poptones
author_rank: Frequent Contributor
timestamp: October 30, 2012, 04:54:22 am
content: How big is the board? Sure fire method for me has always been holding the board a bit above the surface, heat the pad with an iron and then TAP tap it against the bench quick like. Molten solder will hurl down onto your workbench, clearing the hole.

author: cwalex
author_rank: Frequent Contributor
timestamp: October 30, 2012, 07:31:19 am
content: I don't know if this is obvious so my apologies if it is.To clear solder from a hole using a solder sucker add some fresh solder and a little flux. Put the solder sucker on one side of the board and heat the pad on the opposite side of the board and suck it out the hole that way. You can use a nice big fat tip if there is room.

author: Skippy
author_rank: Contributor
timestamp: November 14, 2012, 12:56:16 pm
content: Self bump.What I should have done is watchedThis totally explains why I can do single sided boards but not double sided ones. I'd recommend watching this video series to anyone.

author: xygor
author_rank: Regular Contributor
timestamp: November 14, 2012, 10:05:08 pm
content: Quote from: nukie on October 30, 2012, 03:04:13 amIt sure can. Almost any liquid or solid can be atomized.You probably meant"Lead doesn't get *vaporized* at normal soldering temperature.", which is true.

author: G7PSK
author_rank: Super Contributor
timestamp: November 15, 2012, 06:55:42 pm
content: The risk of using high pressure air to blow the solder out is that the solder will go every where as little pellets which can lodge anywhere on the board causing shorts but more problematical is they could lodge in your eyes, so if you try this wear eye protection, full goggles not glasses.

author: OutThere
author_rank: Contributor
timestamp: July 24, 2020, 12:13:01 pm
content: if you do not need the chip, we use to cut each leg or lead with a pair of diagonal cutters freeing the chip. Then you just had each lead or leg to unsolder.