Materials for spring-loaded probe needles

The needle of a spring-loaded probe is made from a small set of materials: tungsten (W), rhenium-tungsten alloy (ReW), copper (Cu) and the A+ alloy. Needle material strongly affects probe behaviour in service, including elasticity, alignment and how much maintenance the tip requires.

Tungsten and rhenium-tungsten needles

The main materials used for probe needles are W and ReW. Their elasticity is only average: the needle shifts position easily during testing, picks up gold chips from plated pads, and needs to be cleaned many times. Because wear can eventually damage the long needle, service life is also only average.

A+ needles

Needles made from the A+ material have good elasticity, do not shift out of alignment during testing, and do not stick to gold chips, so they need no cleaning. As a result they offer a long service life.