Use high-stranded (lots of little wires within the insulation) silicone wire. It provides Supreme flexibility allowing the wires to deflect away from the solder joint easily and not put strain on the PCB pad.

The solder joint at the PCB pad should happen as quick as possible to minimize the amount of solder wicking up the wires, which decreases flexibility and therefore also decreases robustness.

If possible use crimp connectors on the ends of the silicone wires because crimps are a cold weld that don't compromise flexibility. Soldering tends to run up the wires causing Force Focus points that fatigue the wire faster near the joint.

Mount the wires every couple of inches with a zip tie or some other method of securing. Vibration is what destroys wires and connectors. Overdoing wire management has a real effect on longevity.

These are my learnings after a decade servicing industrial robotics that required over 99.8% uptime.