Escape Ratio
Measured performance metrics define the proportion of defects that bypass inspection gates to reach final assembly or the customer. The fault escape rate calculates the percentage of total faults occurring in a fabrication or assembly process that evade detection during standard quality control cycles. Engineers identify these undetected issues through secondary diagnostic procedures or field return analysis rather than internal production logs.
Detection Logic
Statistical controls rely on the comparison between internal scrap data and external failure reports to isolate the volume of latent problems. Quality management systems subtract the detected defect count from the actual yield loss to isolate the hidden failures. Production teams map this data against specific test equipment capabilities to determine if inspection coverage aligns with the failure modes observed.
Increasing the resolution of automated optical inspection or the sensitivity of circuit testing protocols directly reduces this ratio.
Process Consequence
High failure leakage results in increased warranty costs and significant field maintenance overhead for the original manufacturer. Latent defects remaining in populated printed circuit boards often trigger intermittent electrical shorts or mechanical failures under thermal stress. Sustained reduction in the number of escaped faults correlates with better reliability and lower long term support expense.
Persistent gaps in the inspection chain indicate an underlying failure in the detection strategy rather than an anomaly in production consistency.
