Removing Solder?

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Kruegon

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I have an Eggtimer TRS that I'm working on retrofitting with terminal blocks. The existing wiring appears to be soldered top and bottom. I have no issues heating the solder to remove the wires. But the solder keeps trying to fill the holes. It's also leaving a lump on top of the board. Even if the hole is clean, this prevents the terminal block from seating fully and I worry about it running and shorting the board if I try to heat it and push the terminal block through.

Not looking to buy a desoldering iron. What can I use to pick up the solder off the board while heating it? Thanks.
 

ttabbal

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There are 2 main ways. One is solder wick. It's a ribbon you put over the hole and heat with the iron. The solder is drawn into the wick.

The second is a vacuum desoldering tool. You press a spring loaded pump down, heat the solder, and trigger the pump to suck up the molten solder.
 

jpoehlman

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This Amazon listing has both: Vastar Desoldering Wick, solder braid with 2.5mm Width, 1.5m Length & Solder Sucker Desoldering Vacuum Pump Solder Removal Tool Blue https://www.amazon.com/dp/B01ESUKNXG/?tag=skimlinks_replacement-20

To use the wick, you will first need to tin it with some fresh solder, then place it over the whole you want to remove solder from just at the edge of the tinned part of the wick.

Suckers are good to remove gross excess, but you'll probably need to wick to clean out the hole.

Radio shack use to sell this stuff. Fry's should have it now a days.

Jack
 
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Incongruent

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Some solder wicks already have flux but you may need to add extra flux in order to get the solder to flow.

Video on Desoldering:
[YOUTUBE]N_dvf45hN6Y[/YOUTUBE]
 

Kruegon

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Thanks. I was unaware of the wicks. I wonder if my local radio shack carries it. Thanks for the info.
 

cerving

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I like stuff like this if there is enough room: https://www.parts-express.com/ecg-j...source=google&utm_medium=cpc&utm_campaign=pla
Can sometimes heat and blow out the hole. The cheap sucker takes timing and the wick might not get it all. I use all three. I forgot, there are electric vacuum suckers too. Kurt
Radio Shack used to sell these for about $10, I still have one. I would caution that you should not BLOW the solder out, you shoud SUCK it in. Blown solder will end up everywhere... really bad for something with SMT parts.
 

r66astro

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I don't tin solder wick but I push the wick back towards itself to spread out, it will be wider now.
 

ttabbal

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I don't tin solder wick but I push the wick back towards itself to spread out, it will be wider now.
You don't usually need to. It has flux in it already. Once in a while though, the existing solder decides to be difficult and it can help to add a tiny bit of solder (and flux) to the wick as you heat it.

Note that either method can overheat the board and pull pads off. It takes a little practice. A good rule of thumb is to never heat the board for more than about 30 seconds, let it cool before trying again. Also make certain that you remove the wick with the iron. Even a split second is enough to solidify the solder to the wick, which you pull on, which then pulls on the pad.

Ideally, learn on an old PCB you don't care about. :)

Through-hole stuff is easier to assemble, but rework is painful compared to SMT. Particularly if you have a hot air setup available. I can replace TQFPs with hot air in a couple minutes. A DIP takes forever.
 

ksaves2

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Radio Shack used to sell these for about $10, I still have one. I would caution that you should not BLOW the solder out, you shoud SUCK it in. Blown solder will end up everywhere... really bad for something with SMT parts.
Stick it over a pie tin. Sometimes if sucking doesn't work, blowing gets the hole nice and clean. One has to do what that has to do. I've done things like trying to drill through a hole and the danged drill rips off the pad around the hole.
Then have to scrape the coating of the remaining trace and do a bridge to the component lead. Of course, cleaning SMT pads are a piece of cake for do overs unless of course there is a multiplicity of fine traces close together. Kurt
 

michigander

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removing solder can be aggravating , another option save soldered wire version for a permanent mount


buy a new kit to build with blocks
 

Reinhard

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Another option, without any additional tools required, is the "Slap Method"
https://www.sparkfun.com/tutorials/339

The comments are interesting too. I've only came recently across the article, so I haven't had the opportunity to try it myself and can't vouch for it. The safety warnings seem warranted though.

One thing that I've learned when trying to remove stubborn solder from plated through holes, is that it is often easier to remove a bigger blob of solder than a smaller one. It can help to add some solder, before removing it all together. This will also introduce some fresh flux, which is often beneficial too.

Reinhard
 

OverTheTop

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Reinhard beat me to it on both of his comments. Remember safety glasses (should be used all the time when soldering anyway) when using the "tap" method (slap is too violent I think :) ). Just used this method today to remove a surface-mount part.

Adding solder to the joint helps heaps with extraction. It allows more heat to be driven into the joint so the solder comes out easier. Remember to lay the iron down (chisel tip) to get the best contact with the joint too.

If you are going to purchase a desoldering sucker (they do work well) try to get the largest volume you can. The bigger the sucker the bigger the suck (obvious really!) It is important, as the first bit of suctioning gets the solder out of the hole, and the remaining air cools the leg and the hole lining (barrel) so the solder doesn't re-attach the leg to the barrel of the through-hole. This is assuming double-sided boards of course.

Remember when you are dealing with solder, solder follows three things: Heat, flux and other solder.
 

vcp

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Seconded on adding solder - it helps to conduct heat to the solder that's deep in the hole.
 

boatgeek

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Another cheap and dirty approach is to stick a small toothpick into the hole while the solder is flowing. The solder won't stick to the wood so you can pull it out after it cools. There are probably some reasons that this isn't a good idea, but it did work for me.

I can see the need to wear safety glasses when tapping/slapping, but is there significant risk of spatter when doing standard soldering?
 

OverTheTop

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I can see the need to wear safety glasses when tapping/slapping, but is there significant risk of spatter when doing standard soldering?
It can happen if someone is particularly heavy-handed with the iron and slips, or very unlucky. It is recommended from an OHS point of view. Also, solder suckers spit tiny bits of stuff out the back when you hit the trigger.
 

NateLowrie

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Another thing you may want to try. Use the wick first to get the excess solder on the front and back. Then, heat up the joint till the solder flows and pull out the wire with a pliers while the solder is still liquid. Any addition solder cleanup up nicely with the wick..
 

Kruegon

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Thanks for the tips. Removing the wiring isn't an issue. I do in fact Heat and pull when removing wires. I just need the top surface to be solder free so the terminal block can seat smoothly. I think the wick method should be sufficient for my needs. Now I just need to find the wick.
 

Steve Shannon

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Thanks for the tips. Removing the wiring isn't an issue. I do in fact Heat and pull when removing wires. I just need the top surface to be solder free so the terminal block can seat smoothly. I think the wick method should be sufficient for my needs. Now I just need to find the wick.
You can simply spread or loosen the strands of stranded copper wire, such as in a piece of zip cord and apply flux to it. It's not quite as easy as solder wick, but it will work in a pinch.

Or https://www.amazon.com/dp/B017ODKIPC/?tag=skimlinks_replacement-20


Steve Shannon
 
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