Solder Wick (Desoldering Braid)

Solder wick, also called desoldering braid, is a fine copper braid coated with flux that is used to remove solder from a joint or pad. Press the braid against a solder joint, heat it with a soldering iron, and the flux activates while the molten solder is drawn up into the copper strands by capillary action — the same wicking effect that pulls liquid into a sponge. The result is a clean, solder-free pad ready for a new component. On a mining repair bench it is one of the cheapest and most-used consumables in the drawer, sitting beside flux and isopropyl alcohol as the unglamorous trio behind every clean rework.

How to use it well

The technique is simple but exacting. Lay clean braid over the joint, press a freshly tinned iron tip onto the braid to drive heat through it, wait a moment for the solder underneath to melt and wick upward, then lift the iron and braid together — lifting the iron first lets the solder refreeze and can tear the pad off with the braid. A clean, well-tinned tip is essential, because the braid itself must reach solder-melting temperature and the iron only reaches it through a thin contact patch; a starved, oxidized tip just scorches flux without moving solder. Adding a touch of extra flux, or a dab of fresh solder to the tip, dramatically improves heat transfer into stubborn joints. Used sections of braid saturate quickly and stop wicking — trim them off so fresh copper is always presented. Width matters too: narrow braid for fine-pitch pads, wide braid for ground pours and connector tabs that soak heat.

Solder wick on the hashboard bench

In ASIC repair, solder wick's headline job is pad cleaning after chip removal. The standard hot-air rework procedure for replacing a failed hash chip runs: flux around the chip, heat at roughly 350–380 °C, lift the chip when the solder melts — then clean the pads with solder wick and flux before the replacement goes down. Those BGA pads must be dead flat; any leftover solder bump will tilt the new chip and produce opens or shorts under it, invisible until the board fails test. The same applies after removing a DC-DC converter, a PIC socket, or a damaged connector on a hashboard: wick the pads flat, clean the residue, inspect, then rebuild. Because a replacement BGA chip is either factory-new or salvaged and reballed with fresh 0.4 mm spheres during BGA rework, the board-side pads contribute their solder volume too — which is exactly why they must start clean and uniform before reflow.

Wick versus pump versus hot air

Each desoldering tool has its lane. A spring-loaded desoldering pump excels at emptying through-hole barrels — power connectors, headers, electrolytic capacitors — where a slug of solder must be pulled from a hole. Hot air removes multi-pin surface-mount parts whole. Solder wick is the finishing and precision tool: flattening pads, clearing solder bridges between fine-pitch pins, tidying a joint after pump work, and removing small passives in a tight area without bathing neighbouring components in hot air. That localized heat is a genuine advantage on a dense hashboard, where an ASIC or a temperature sensor may sit millimetres from the joint you are working; the wick heats one joint, not a zone.

Buying and keeping it

Braid is graded by width and comes flux-impregnated ("no-clean" or rosin) or bare; flux-impregnated is what you want, and even then a little added flux helps. Keep it sealed — the flux coating degrades and the copper oxidizes with humidity, and old braid wicks poorly. It costs little enough that replacing a stale roll is never the wrong call. A clean pad is the foundation of every repair that follows it, and solder wick is how pads get clean.