Solder versus Crimp Comparison
On wiring harnesses exposed to vibration, crimping is the termination method preferred over soldering. Solder turns the conductor into a stiff block and a stiff-to-flexible transition forms where the solder ends; repeated bending stress concentrates exactly at this point and breaks the conductor by fatigue.
Solder gives a good contact electrically; the problem is mechanical. Molten solder wicks between the strands by capillary action and locally turns a flexible stranded conductor into a solid rod. When the cable bends, all the bending gathers at the boundary of this stiff region.
- Fatigue fracture: the stiff-to-flexible boundary is where the crack starts under repeated vibration.
- Thermal effect: the soldering temperature hardens the copper and reduces its ductility.
- Difficulty of repair: when a soldered end is undone and remade, the insulation recedes and the loss of length accumulates.
There are places where solder is appropriate: board-level connections that do not move, short ends fixed inside an enclosure and special connections for which no crimp terminal exists. When you have no choice, support the soldered end with sleeving and clamp the cable right behind the soldered zone so that the bending load is kept away from the solder boundary. On high-current power connections, use a pressed lug.
Context in which this term is used: Installation, redundancy and field continuity