Discontinuity Fault
Measured against continuous electrical continuity standards, temporary losses of electrical connection create elusive failure modes in operating electronic assemblies. An intermittent open occurs when an electrical path breaks sporadically under specific mechanical or thermal conditions and subsequently restores itself. Microcracks within solder joints, fractured plated through-holes, cracked ceramic substrates and oxidized connector contacts frequently exhibit this behavior.
These temporary circuit breaks disrupt signals without leaving permanent structural damage that standard static continuity tests catch easily.
Stress Sensitivity
Thermal expansion mismatches between circuit substrates and surface mount packages induce cyclic mechanical strain on solder joints. Under operating thermal loads, a microcrack opens, causing an intermittent open that disappears when the assembly cools back to ambient room temperature. Vibration and mechanical shock similarly flex circuit boards, momentarily separating fractured conductive interfaces.
Environmental stress screening subjects assemblies to combined thermal cycling and random vibration to force these transient faults into permanent open circuits during factory testing.
Diagnostic Challenge
In-circuit testing and traditional functional testing often miss transient discontinuities because test conditions fail to recreate operating physical stresses. Continuous event detection monitoring during environmental stress testing captures microsecond resistance spikes indicating an intermittent open. High-speed glitch detectors isolate affected channels before field deployment.
