How to remove and replace a through-hole component
How to desolder a through-hole component with a pump and desoldering braid, clear the holes and fit a replacement without damaging the PCB.
Add solder before removing it
It sounds backwards, but old or lead-free joints on factory boards melt badly. Adding a little fresh leaded solder and flux lowers the melting point and lets the joint melt all at once.
Two-lead parts
For resistors, diodes and small capacitors: heat one joint and pull that lead gently with tweezers from the top side, then the other, rocking the part out. Then clear the holes.
Parts with many pins
- Flux every joint.
- Cock the pump. Melt one joint fully, place the pump nozzle over it, and trigger immediately after lifting the iron.
- Clean what remains with braid: flux, braid on the pad, iron on the braid, lift both together.
- Check each pin moves freely before pulling the part. If one sticks, reflow and clear it again. Never pull hard.
Fit the new part
Check orientation marks first: the stripe on diodes, the minus on electrolytic capacitors, pin 1 on chips and connectors. Insert, bend the leads slightly to hold it, solder one pin, check the part is flat and straight, then solder the rest.
Common mistakes
- Pulling a part while one pin is still soldered, which rips the plated hole out.
- Holding the iron on for ten seconds or more. Heat damages the board and the parts around.
- Dragging braid across the pad.
- Fitting the new part backwards.
Stop if a plated hole comes out with the lead, if the board has more than two layers and a pin connects to a large internal plane, or if the part is a connector carrying power. Repairing a damaged via or plated hole needs a bench and the design files.
Kit list
| Item | What to look for | Buy |
|---|---|---|
| Temperature-controlled soldering iron | Adjustable 200 to 450 °C, 60 W or more, fast heat-up, replaceable tips. The single most important tool. | View on Amazon ↗ |
| Spare tips for your iron | A 2 mm chisel for general work and a 1 mm conical or small chisel for fine pads. They must match your iron model. | View on Amazon ↗ |
| Leaded solder wire, 0.5 to 0.8 mm | Sn63/Pb37 or Sn60/Pb40 with flux core. Easiest to use; for repairs and prototypes, not for products sold in the EU. | View on Amazon ↗ |
| No-clean flux gel (syringe) | Thicker than a pen; stays in place for SMD work and desoldering. | View on Amazon ↗ |
| Desoldering braid, 1.5 to 2.5 mm | Copper wick that soaks up solder. Buy fluxed braid. | View on Amazon ↗ |
| Desoldering pump | Spring-loaded sucker for clearing through-holes. | View on Amazon ↗ |
| ESD-safe precision tweezers | Fine straight and curved tips to hold small parts. | View on Amazon ↗ |
| Isopropyl alcohol 99 % | Removes flux residue after soldering. | View on Amazon ↗ |
| ESD cleaning brush | Stiff anti-static brush to scrub flux with alcohol. | View on Amazon ↗ |
| Magnifier or USB microscope | To inspect joints. Most bad joints look fine to the naked eye. | View on Amazon ↗ |
Links go to Amazon. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. We only list tools of the kind we use on our own bench.
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