A cold joint forms when solder melts incompletely or the parts never reach wetting temperature, so the solder sits on the surface without a proper metallurgical bond. It looks dull, grainy or lumpy, with a poor fillet or visible gaps, and may conduct at first and then fail intermittently. Causes include a large copper plane sinking the heat, too low an iron temperature or dwell time, and oxidised or contaminated surfaces the flux cannot clean.
That connector's ground pins are all cold joints, the plane is sucking the heat out, use a bigger tip and preheat.
Also heard as
- cold solder joint
- cold solder
Related terms
Thermal relief
Spoked connection between a pad and a copper plane that limits heat flow so the joint can be soldered.
Wicking
Solder or plating chemistry drawn by capillary action where it is not wanted, up a lead, into a via or along glass.
Rework
Removing and replacing parts or fixing joints on an assembled board to correct defects or make changes.