Tension Loss
Reduction in the vertical pressure exerted by a spring-loaded contact over time or repeated use defines a failure mode in automated test equipment. Probe force decay happens when the internal spring material loses its elasticity and can no longer maintain the required gram-force against a contact pad. It leads to intermittent electrical connections that frustrate the accuracy of functional tests.
This phenomenon is a primary consideration in the maintenance schedule of high-volume testing facilities.
Stress Factor
Elevated temperatures inside a burn-in oven accelerate the weakening of the spring alloy. The stress factor of probe force decay involves the molecular rearrangement of the metal under constant compression at heat. Testing cycles that exceed the rated lifespan of the probe also contribute to the gradual loss of return force.
Regular verification with a load cell ensures that each pin provides enough pressure to pierce through surface oxides.
Failure Threshold
Inadequate contact pressure results in false open circuits. The failure threshold of probe force decay is reached when the contact resistance becomes unstable due to low mechanical bias. Once a probe falls below eighty percent of its nominal force, the risk of data errors justifies the replacement of the entire pin set.
