Removing solder from stubborn joints

[pharaoh3]

I have a PS4 controller that I want to replace the joystick on, so I disassembled the controller, added flux, added additional solder to all the joints, and removed the faulty joystick with a heat gun. Everything went well, but I ran into a few problems during the next step which was removing all the solder from the joints with a soldering iron, solder sucker, and a wick. The problem is that I have a few joints with a incredibly thin amount of solder that is quite difficult to remove since I can't get my iron and sucker on it at the same time. What is the best way to remove the solder ?



I have tried adding additional solder, adding more flux, using a wick, and heating up the board with a heatgun then switching to the iron. I have even tried attaching a resistor to the joint, adding solder, and then attempting to remove the solder again. What do I do? Note: This is for fun/practice, and not for a professional repair, so I am willing to experiment.

[ataradov]

Sharpen a toothpick and poke a hole in the molten solder. Then remove the extra solder that comes out on the other side.

[pharaoh3]

Sharpen a toothpick and poke a hole in the molten solder. Then remove the extra solder that comes out on the other side.

I don't think I could fit my soldering iron and a toothpick on the joint at the same time.

Plus, I don't have a toothpick handy...

[ataradov]

Why? There is lots of space on the board. Just hover the toothpick over the hole and once the solder is molten, push it though the hole. This is a standard method for dealing with stuck holes, it always works.

Wood can take quite a bit of heat, so heating the annular ring will let you push the toothpick though the hole further.

Get anything wooden. There must be something around, like a match.

Otherwise you will just destroy the board. There are not too many methods of dealing with this.

Also, it does not look like you have enough flux judging by the picture.

[pharaoh3]

You sound confident that this is the technique to use. I turned in for the day, so I will have to report back tomorrow

[Microcheap]

For these situations I have a set of hollow needles like this one: https://www.aliexpress.com/item/33004594843.html

I use a soldering iron with a chisel tip to better spread the heat, apply some fresh solder and then I poke the hole with the needle of the right diameter, the result is a clean via and no damage to the board.

[ataradov]

I tried those needles, but they are way too big. Plus they are metal and cool down the solder faster. And I always find myself going back to the plain old toothpick.

[nigelwright7557]

I use a solder sucker with a silicon tube around the end for a better seal.

Sounds counter intuitive but fill hole with fresh solder.
Heat up fresh solder and quickly put solder sucker over hole and press the button.

Sometimes you have to suck from both sides if other side has a lot of copper attached.

Sometimes copper desolder braid helps.

[mdubinko]

Solder wick should be able to do this, after adding a bunch more flux. Use the pointiest iron tip you have, and heat through the copper wick into the hole and all the solder within should, well, wick right up. It looks like there might be enough solder to saturate a segment of the braid, in which case you might have to move it while maintaining heat. And yeah, if the last bit of solder left is deep down, it can be hard to get it all in one 'slurp'.

Mind if I ask what brand of solder wick you're using? I've picked up some wick from Aliexpress that was worse than unusable, but genuine stuff from a reputable source will be orders of magnitude better.

Worst case, I would use some low-melt solder to give yourself more working time (and then use wick to clean up all the low-melt solder)
-m

[mzzj]

Proper desoldering gun makes night and day difference in this kind of cases. Well worth of the 100-200usd investment if you have more than one-time use for it.

Other than that:
Preheat the board with hot air gun
Fill the via with fresh solder
Use flux
Use 2 soldering irons simultaneously on both sides of the board (or soldering iron and desoldering gun)

And like already mentioned the desoldering braid brand makes big difference!

[Martian Tech]

I can't get my iron and sucker on it at the same time. What is the best way to remove the solder ?

You simply use the sucker on the other side of the board from the iron.  Stand the board up vertically somehow, put the sucker in place and hold it there while applying heat from the other side of the board with the iron.

[Microcheap]

I tried those needles, but they are way too big. Plus they are metal and cool down the solder faster. And I always find myself going back to the plain old toothpick.

I've never tried the toothpick but the hollow needle works nicely for me.

I normally just use a solder sucker with a silicon tube on its tip and it does the job for most of the vias but for areas of the PCB with a big cooper plane where the solder will solidify before I can sucker it, I find easier and faster to use those needles.
Try to use a bigger chisel tip (I like the T12-D32) with fresh solder and then keep the iron touching the pad while leaving the via accessible for you to insert the needle in it. It works even better if you can heat the pad from the other side of the PCB.

I also have a de-soldering station but I rarely use it. The solder wick didn't work for me but that is because I can get only those junk from Aliexpress, good quality stuff should work fine.

[Haenk]

heat with tip from one side, poke from the other side
For tiny holes, I use a sewing needle, however these are one or two time use only, eventually solder might stick to it.
 

[Psi]

You can add more solder to make the hole full, then hold the heat on it with a large flat tip, giving it some time to soak. Then, move the iron out of the way fast and instantly blow the solder out by blowing at it really hard at point blank range.
But your face has to be very close to it and also gets very close to the iron. So it's definitely a learned skill with a high risk of burning your face if you do it wrong.

Another hacky method is to hold the heat on with the iron from one PCB side and then put the nozzle of the vacuum cleaner on the other PCB side. Open the air relief intake value thing a bit, so the suction is not crazy

but really, I recommend good quality solder wick and some flux

[DavidAlfa]

I've changed few of these. Rohs solder + multilayer ground planes don't make it too easy.
99% of the time it's caused by the iron, lacking power or using a tip head that can't transfer enough heat.
So when you thing the solder is melted, it's only the surface layer.

The copper braid will take heat from the solder joint, so when there're ground planes involved, it's not the best option!
First, use a wide, thick tip, put it on the bottom side, but watching from the top.
Add some solder on the top, keep heating until it melts. Now you know it's fully melted all the way through.
Take a cheap piston pump, and give it a shot! Clean hole with no effort!
Don't be unpatient when heating it up. You want the solder fully melted.
If you only take part of it, like in your picture, it'll be very hard to clean.
Not only that, It'll require a lot of heat, causing a lot of stress on the pcb and risking to damage it.
When that happens, you need to refill it with fresh solder and try again!

[HB9EVI]

for such cases I refresh the pad with new solder and remove it, normally that helps to get the residues from the old solder off with it; if not, some flux from the syringe should help.

if all doesn't help, heat up the pad and blow pressurized air through the hole (the use of non-inflammable pressurized air is highly recommended)

[rfclown]

You don't have to remove all the old solder, just enough to get the leads of the new part on. For clearing out the hole I've used a dental pick (I guess like the toothpick and needle mentioned). I put the base of the dental pick on the bench and have the point on the back side of the board on the hole to clear out. I hold the board so that the dental pick is suspended straight vertically using only the pressure of the board (it's precarious, but avoids needing a third hand). Then I heat the top side of the hole with an iron while pushing down on the board. When the solder melts, the stainless steal pick will ram through the hole. On the flip side I used to remove through hole components in a similar manner. Clip a hemostat on the part, hold the board upside down, heat solder joints. Then the solder is melted, the weight of the hemostat pulls the part out.

[BreakingOhmsLaw]

Get an "Engineer SS-02 Solder Sucker". It has a silicone tube instead of a solid nozzle. That really seals around the hole and pulls the solder out. Never fails me if used correctly.
You get two inches of spare tube with it that you can cut off and replace it with.

https://www.engineertools-jp.com/ss02

The only issue I have with it that is is on the small side. That's good if you need to cram it in awkward positions, but if you have shovel hands it is a bit fiddly.

EDIT: For the really tough annoying cases like ground planes that pull the heat out, get "ze secret weapon":
SN42/Bi58 bismuth solder wire. Oh baby. It drops the melting point of solder to ridiculously low temperatures.
Works like a charm, just don't use it on anything that gets hot during use, it'll unsolder itself even if minimal traces of bismuth are left in the final solder joint 

[Shock]

To clear solder blocked holes use fresh leaded solder and flux both sides then a solder sucker. If it's stubborn heat from one side and suck from the other. A small amount of residue is fine if pin/leg insertion is possible.

[pharaoh3]

I have no idea what brand. It's some Chinese stuff. I am using some Chinese solder that's supposed to be 60/40. I've noticed on some joints I have a hard time apply the solder.

The wick I have seems to do a decent job, but it doesn't help with this issue. The best solution I've noticed so far is apply solder and removing it about 15 times, but that is incredible time waster. I was able to disassemble a broken controller today and desolder the components in under 10 minutes, but I got stuck on a single joint for hours. I think I fried the board too cause now it won't turn on.

[pharaoh3]

I can't get my iron and sucker on it at the same time. What is the best way to remove the solder ?

You simply use the sucker on the other side of the board from the iron.  Stand the board up vertically somehow, put the sucker in place and hold it there while applying heat from the other side of the board with the iron.

I actually do this and it isn't effective on these joints for some reason. This is why I'm tearing out my hair.

[pharaoh3]

but really, I recommend good quality solder wick and some flux

How can I tell if it's high quality? I just order random Chinese shit off ebay and hope it arrives.

[pharaoh3]

I've changed few of these. Rohs solder + multilayer ground planes don't make it too easy....
Not only that, It'll require a lot of heat, causing a lot of stress on the pcb and risking to damage it.
When that happens, you need to refill it with fresh solder and try again!

What's ROH solder?
Also, what are the non obvious signs that a board is damaged? I was completed a swap on a practice board, but it won't turn on, and I don't see any obvious signs of damage.

[pharaoh3]

Why? There is lots of space on the board. Just hover the toothpick over the hole and once the solder is molten, push it though the hole. This is a standard method for dealing with stuck holes, it always works.

Otherwise you will just destroy the board. There are not too many methods of dealing with this.

Also, it does not look like you have enough flux judging by the picture.

Are you inserting the tooth pick while the iron is on or are you swapping them out?

I'm having a hard time getting the solder molten on that joint. It seems to glob together instead of getting molten and liquid.

I asked this of somebody else too, but I want to hear your opinion.  I sucussfully swapped on the joystick on a different board, but now it won't turn on? Did I fry the board? There aren't any obvious signs of damage.

I cleaned the board before taking the picture.

[ataradov]

Are you inserting the tooth pick while the iron is on or are you swapping them out?

At about the same time. You melt the solder, move the iron slightly to the side and insert the toothpick.

I'm having a hard time getting the solder molten on that joint. It seems to glob together instead of getting molten and liquid.

Not enough flux or too low temperature. Or you are doing something else wrong. Hard to tell.