Removing solder from stubborn joints

[pharaoh3]

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

It's strange since I'll do several joints without a problem then I'll find one or two they just act differently. Maybe those are absorbing the heat differently.

My heat is fairly high at 350-380c. I've been using 420c on my heat gun with low air pressure.

[ataradov]

It's strange since I'll do several joints without a problem then I'll find one or two they just act differently. Maybe those are absorbing the heat differently.

This happens to pins connected to the ground plane. Even with thermal reliefs, they still "feel" different and absorb more heat.

[semir-t]

When this happens to me, I sometimes do the following:
1. I hold the PCB with left hand
2. I hold the soldering iron with right hand and I am heating the hole that has solder in it
3. When the solder is in liquid state I start moving the PCB and soldering iron (while still trying to heat the hole with solder in it) in one direction (as fast as possible) and then after 10-20 cm I instantly stop. The idea is that inertia will cause solder to exit the hole.

This sometimes works for me and sometimes it doesn't but it's worth a shoot.

[Shock]

I know at least 20 ways to fix this but it would be a book and likely solved by my previous post and using "name brand" solder like Kester, Loctite (Multicore) or any well established non chinese brand. Inferior alloys, flux, plus unregulated and potentially dangerous contaminants are used in low cost and counterfeit products.

[djsb]

Decent solder braid I use.
Goot wick: Available in various widths-Expensive but VERY good-made in Japan.
Techspray: Used some that was included in a ChipQuick kit.
Multicore: You can buy this in large reels, so works out cheaper.

A proper desoldering handpiece is the best tool for this job. That is, providing you can find a bit with the correct size hole that accommodates the stub of the component lead.
The engineer desoldering pump is also very good.
Also, a soldering Iron with the heating element as close to the soldering joint as possible is best. I use a PACE MBT 350 that has the heating element in the actual bit. Metcal stations also use this approach, although the temperature is not variable like on the PACE.

[DavidAlfa]

I'm tied to Chem-Wik, USA brand. They have tons of flux, the solder flows like a river on these.
I usually buy 15 or 30m reels in eBay for around 20euro.
They last a long time and the cost/meter is actually cheaper than any crappy chinese brand, they all suck, but not solder!
Search Chem-wik or Chemwik (the results vary quite a bit).
It doesn't degrade over time, I'm finishing my current roll after 3 years, it still works like new, no special care, no air-tight storage, I just throw it away when I'm done!

They also have 500ft (150m) rolls, that's crazy!

[perieanuo]

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

indeed the toothpick never will be obsolete. or some good pump after you got how it works, +- silicone tube attached or not.
never guessed the toothpick thing gets out of eastern europe  i thought it's our registered patent

[ataradov]

never guessed the toothpick thing gets out of eastern europe  i thought it's our registered patent

I'm originally from Russia and learned about the toothpick from my dad

[perieanuo]

I'm originally from Russia and learned about the toothpick from my dad

me,when i was almost 40, in france, from a romanian pcb designer, he had crappy de/soldering tools (i had to convince him to buy hotair station and some other common-sense tools for r&d lab, the guy soldered his bga's in hungary at his friend's company) 

[pharaoh3]

I'm convinced its the solder that is used on the PS4 Controller. It seems to clump together much more than other solder I have seen. Plus when I dilute it with 60/40 solder it tends to clump, but when I use lead free I have no issues. However, it is very difficult to remove.

Today, I replaced the joystick on my Xbox One controller, and it was incredibly easy in comparison to the PS4 controller.

[Mario87]

If you want to make your life very easy, get some low melt solder. It's pricey, but you don't need much. Add some of that to the hole, then heat it up and use wick to remove it / clean the hole.

The issue will be that these holes are likely connected to internal and possibly external GND layers that are absorbing a lot of heat. If you don't have a good iron that can maintain temperature, you will have this issue.

As someone else said, there are many, many different ways to skin this cat (de-solder gun, de-solder pump, heating with hot air & iron simultanously, using a needle / toothpick, etc, etc). However, by far the easiest is to reduce the melting point of the solder so that the wick can readily absorb it before it cools down and hardens.

As such, some low melt solder will do the job just nicely.

[pharaoh3]

If you want to make your life very easy, get some low melt solder. It's pricey, but you don't need much. Add some of that to the hole, then heat it up and use wick to remove it / clean the hole.

The issue will be that these holes are likely connected to internal and possibly external GND layers that are absorbing a lot of heat. If you don't have a good iron that can maintain temperature, you will have this issue.

As someone else said, there are many, many different ways to skin this cat (de-solder gun, de-solder pump, heating with hot air & iron simultanously, using a needle / toothpick, etc, etc). However, by far the easiest is to reduce the melting point of the solder so that the wick can readily absorb it before it cools down and hardens.

As such, some low melt solder will do the job just nicely.

All right mate! I am getting a de-solder gun and low melt solder! I'm tired of letting this problem defeat me!

[djsb]

With the low melting point solder (ChipQuik et al)you need to make sure that you are able to remove it all from deep within any plated through holes. I've only ever used this solder on surface mount parts.

[abdulbadii]

ensure solder is molten & the fluxed fine wick hot  so that can get wetted smoothly
likely it's not such adequate heat due to it's drained by other massive metal/conductor

[geggi1]

Solder iron and sucker would work well on this board for the through the hole pads.
Sett up the PCB vertically with a small vice or something similar.
Heat the solder pad on one side and hold the sucker on the opposite and suck out the solder when it flows.

[grendle373]

"Chip Quick" low melt solder makes quick work of these.  Be sure to get it all off though, I like to resolder with kester 44, then wick that, and you should be good to go. 

[nigelwright7557]

I have a solder sucker wit ha hard plastic tip.
The hard tip isnt good for a seal so I put a short piece of soft silicon tubing over the end and that seals much better.
Put solder in hole, heat up with iron, remove iron and quickly move in with solder sucker and suck.

[abdulbadii]

Use clean desoldering iron
Unclean one won't work as heat is dismissed to many metal area else including the solder inside the tool

it should work unless target point is contacted to massive conductive plate

[BrokenYugo]

When this happens to me, I sometimes do the following:
1. I hold the PCB with left hand
2. I hold the soldering iron with right hand and I am heating the hole that has solder in it
3. When the solder is in liquid state I start moving the PCB and soldering iron (while still trying to heat the hole with solder in it) in one direction (as fast as possible) and then after 10-20 cm I instantly stop. The idea is that inertia will cause solder to exit the hole.

This sometimes works for me and sometimes it doesn't but it's worth a shoot.

Works better if you run the board into something, I usually use a roll of solder. Just hold the board a few cm above and flick it into the "anvil". If you cut a part off the board this will usually knock out cut off chunks of component legs too.

[geggi1]

This kind of problems is normally pretty simple to solve.
1. You need some kind of clamping to hold the PCB in posisjon this will free up your hand and make you able to work two handed. the clamping can be a small vice, G-clamps, "third hand" device or something similar.
2.  Then you need a solder sucker pump of some kind. This can be some of these cheep piston things with a spring inside just be sure to get one with PTFE tip.
3. Decent solder iron no less than 50W and temperature control. Stannol type is better because there is more mass in the head and this will prevent the temperature from dropping. Weller solder stations is not so good because the small head.
4. set the PCB up in your preferred clamping.
5. heat your solder iron to +400C and put a good bob of solder on top of the solderpad. The bob should cover the pad and be 2-3mm high. Keep the solder hot with the iron.
6. use your piston sucker from the opposite side of the PCB and clean out the via.
7. clean the pad with solder-wick if required.

The most important when cleaning vias is good solder, high temperature and use two hands.

A tip about these piston suckers. use some wd40 or similar penetrating oil inside. the cleaning will be simpler.

[djsb]

If you're using 400 degrees C on your iron, be prepared for your pads lifting or damage to the board substrate, or both. If you are de-soldering a large earth plane without reliefs then a high temperature is justified. However I would not go above 300 degrees C. What's important is the rate at which heat is transferred from the heating element to the joint. I use a PACE iron where the element is actually in the bit itself, so heat transfer is very quick. Likewise with a Metcal (apart from the fixed temperature).

[Ian.M]

*DONT* use WD40 or penetrating oil to lubricate your solder sucker unless it has absolutely no plastic parts under spring load, as you risk it micro-crazing the plastic parts due to poor chemical compatibility, and as a result, your solder sucker violently disassembling itself during use!   Instead, use light silicone oil, which you may already have around: e.g. DOT 5 brake fluid or silicone copier/printer fuser oil, which has much better chemical compatibility with nearly all plastics (excluding silicone rubber, but your sucker shouldn't have silicone O rings as they get torn up too easily by solder dross).  See my comments here: https://www.eevblog.com/forum/reviews/upgrade-the-o-ring-of-goot-soldapullt-desoldering-tool/
and also my suggestion for a wiper to reduce the amount of solder dross that reaches the O ring, increasing the maintenance interval and improving suction in reply #16 here: https://www.eevblog.com/forum/repair/de-soldering-advice-loosing-my-mind/
The rest of that thread is worth a read as well.

Here's a picture of the wiper mod for solder suckers that us a compression spring in the chamber.  A waxed paper wiper disk can be seen bottom left and also several between the spring and the plunger.  Sorry its such a crappy photo!

[m k]

Why big iron and manual sucker is not a norm?
The case seems to pretty always be a lack of heat and/or speed.

Back in the day when CRT was a thing and horizontal deflection high some joints didn't like it at all.
Finally solder compound changed totally and became something that didn't melt.
Drilling wasn't an option so repetition was all that was left.
Then finally you just give up and decide it's clean enough.

We had rules of course and some parts had to be scrapped but for VT100 and friends there were no rules, or one, make it happen.
(obsolete stuff, no new parts, or was but astronomical price, manufactured(late '80s) on your request)

New solder was a key then.
Now it's more accurately new flux.

I've never tried pulling stuff out slowly, if not lifting a leg, but pushing it down many times.
There I've used normal copper wire and two irons, old tip with hooked top will help.

My desoldering iron is set to ~360C, no idea what it really is.
You're also supposed to heat the joint and not the board, so as big a tip as is practical is the way.
If you must touch the board with the iron remember that dry board will take the heat, so to speak.