How to desolder an element from a PCB?

Question

I want to desolder an element from a PCB, I can see all the solder joints that are holding it on to the board and I can reach all of them easily.
I am not very experienced in working with a soldering iron, tbh this is the first time I am working with one but I informed myself how to do it correctly and I also got myself a desoldering pump to remove the melted solder joints.

The only thing that is giving me headaches is the fact that I read it can be difficult to desolder solder joints that are close or on a ground plane because the ground plane absorbs heat.
I took a look at my board and this may be the case for 3 or 4 of them.

My question is do I have to take special care of those solder joints, do I need a specific tool to remove those or can I remove them just like the others?

Answer 1

Whenever you have to desolder something the first question you need to ask yourself is: do I need the component intact?

Because if you removing damaged component then often the easiest way is to separate its pins first. For most but the smallest SMD components this can be done with wire cutter. The plastic connector shroud can be broken or melted away etc. Once you've done that removing pins one-by-one becomes trivial.

If you do need the component, see if you can distribute heat to all pins simultaneously. For 2-5 pins this usually can be done by adding solder to the pads, making a blob of molten solder. For more pins you can cut a piece of heavy gauge copper wire and put it along the pads, then cover everything in solder and keep heating until all pins got loose. Here is very good video demonstrating this technique.

Pump and/or wick can be used afterwards to clean the pads.

In either case having an iron suitable for the job is most important. Big chisel or screwdriver type tips work best for this.

Answer 2

Tricky, especially if you are not experienced. It's a connector?

What I would try is first go along the pads with a solder sucker, suck out solder, and check that each pin is physically free with the tip of a small screwdriver or similar. Also use solder wick to draw solder out. Sometimes you have to refill the hole with solder and repeat before you can get enough solder out. Even so it depends a bit on how big the hole is compared to the pin going through. If the fit is too tight this won't work.

The other option is to try to heat all pads at once and then prise the component out. A hot air gun (the type for surface mount soldering) is good, but you have to be careful not to overheat the board and the component.

It's not really a beginners job, to be honest. Needs a bit of experience, the right tools, and some patience.

Answer 3

Depending on the geometry of the pads and how they are connected to the ground plane, they will require longer heating to let you remove the solder.

A tip is to use a bigger solder tip, which has more thermal mass. It will help delivering enough heat before it is drawn away by the ground plane.

Answer 4

• Decide if you want to keep the board or the component intact. Keeping both intact is a hairy problem even for experts.

• Desoldering lead-free solder joints is tedious. It's actually easier if you first generously add leaded solder (SnPb38Cu2 or SnPb38Ag2, not SnPb40!). Connect all the pins with solder. Solder in a thick copper wire bridge as a helper.

• Heat the whole thing up at once.

• Pull the component. Congrats, you are almost done.

• Remove the wire bridge.

• Use solder wick to remove the solder from the vias. Don't use a pump, they tend to reap the copper eyelets from the board.

Answer 5

This can take a while. Desolder pumps are nice, but desoldering wick can also be useful.

Where it's not contraindicated, the easiest way is to cut the piece, and take out the pins one at a time.