Sooner or later, after soldering, you find a part in the wrong direction, need to replace a faulty part, or need to fix wiring. If you tear a part off by force at that point, the pads lift and the board is ruined. If you know the tools and the order for removing solder cleanly, you can safely make corrections any number of times. This article covers how to use solder wick and a solder sucker, the removal order by type of part, how to avoid damaging pads, and how to save a damaged pad.
Tools for removing solder
| Tool | Method | Characteristics |
|---|---|---|
| Solder wick (desoldering braid) | A braid of copper wire soaks up molten solder by capillary action | Cheap and easy to learn. Good for tidying up solder left on a pad |
| Solder sucker (desoldering pump) | Sucks up molten solder instantly using spring force | Removes solder from a through-hole part in one go |
| Desoldering gun or station | Heating and suction in one body | Convenient for people who correct often |
| Hot air | Heats with a stream of hot air | Removing SMD parts (almost unnecessary on perfboard) |
For beginners, having one solder wick and one solder sucker is enough.
How to use solder wick
- Applying flux to the end of the wick, or using a part with flux on it, makes it soak up solder much better (Choosing Solder and Flux).
- Place the wick on the solder to be removed and put the iron tip on top of it, so the solder melts and is drawn up into the wick.
- Pull the wick away together with the iron, sliding it flat across the pad. Do not pull hard while the wick is stuck to the pad. If the solder sets, the pad is torn off.
- Cut off the used part and use a fresh section.
How to use a solder sucker
- Press down the sucker's plunger to cock it.
- Melt the soldered joint completely with the iron.
- Put the sucker nozzle close to the molten solder and press the button to suck it up. Timing is important. You must press right at the moment the solder melts.
- Clean it when residue builds up inside the nozzle.
Removal by type of part
Parts with 2 to 3 leads (resistors, diodes, capacitors, transistors)
- Remove the solder from one lead with solder wick or the sucker.
- Remove the other the same way.
- Wiggle the part slightly, and if something catches, remove more solder from that lead.
- When both leads are free, slowly pull the part out.
If you are in a hurry, there is a way to melt one lead's solder with the iron, pull the part slightly, and then melt the other side, but heat is applied to the part for a long time, so use it only on cheap parts.
ICs with many leads
It is hard to take an IC off all at once. We recommend this order.
- Using an IC socket is the best prevention. If it is plugged into a socket, you do not need to touch the soldering when pulling it (Reading DIP IC Pin Numbers).
- If you soldered without a socket, remove the solder from each pin with a solder sucker. For 14 pins, repeat 14 times.
- For pins still attached after using the sucker, finish with solder wick.
- Press each pin one by one with tweezers to check that all are free, and slowly pull the IC up.
- If it absolutely will not come off, cut off the IC body (giving up on the IC), pull the pins out one by one, and clean up the holes.
When a hole is plugged with solder
For solder blocking a hole, melt it with the iron tip and push it through with a toothpick or a thin pin, or suck it up with a solder sucker. If you push a part by force inside the hole, the copper plating comes off.
When a pad has lifted
Overheating or applying force can lift a pad off the board or detach it.
- Finish the work on a pad within 5 seconds. If heat is applied too long, the adhesive melts and the pad rises.
- If a pad has come off, do not use that hole again; use a neighboring hole and connect with a jumper wire. In a design tool like Patterndo, just redraw with the layout slightly changed.
- For a pad that is only half lifted, hold the part in place, press the pad down with epoxy or super glue, and then solder.
Tips for resoldering
- When soldering back into a spot you cleared, tidy up the pad and the hole and use fresh solder and flux. Old solder is oxidized and does not stick well.
- Even when you replace a part, solder it from the same side in the same way (Soldering Basics).
- After the fix, recheck for shorts between adjacent pads with a continuity test (It Is Finished but It Does Not Work: A Step-by-Step Checklist).
Habits that reduce corrections
Before soldering, check orientation and placement in Patterndo (especially IC orientation and polarity), and solder one part at a time from the shortest parts, checking with a continuity test. Most moments when you need to correct something come from skipping the checks.
Summary
The core of removing solder is using fresh flux, with the solder fully melted, and without applying force. Keep solder wick for tidying and a solder sucker for through-hole removal, and use a socket for ICs from the start. If a pad is damaged, work around it with a jumper. For safety while working, see Soldering Safety.