Mathematical Rule
A mathematical equation used in electronics manufacturing assigns the root cause of an uncaught PCB defect to either a failed inspection routine or a subsequent processing step. Under the escape attribution formula, engineers calculate the probability that a specific solder bridge or missing component should have been detected by automated optical inspection prior to the reflow stage. When the calculation is applied, it divides the responsibility for defects between the fabrication line and the assembly line.
Industrial Application
Quality assurance departments use this calculation during post-assembly auditing to refine the programming thresholds of automated inspection equipment. High yield environments rely on the math to distinguish between false calls and actual missed escapes. By analyzing these ratios, process engineers can identify whether a defect represents a mechanical failure in the pick-and-place machine or a program weakness in the inspection algorithm.
If the escape rates of a specific defect class exceed the baseline, the inspection software is retrained with tighter tolerances. This systematic loop drives down defect levels while protecting the line speed from excessive manual intervention.
Practical Boundary
The calculation is valid only when the inspection system and manual logs provide complete records of every board. If the tracking database contains gaps, the mathematical model breaks down. This restriction prevents the formula from being used on non-serialized high-volume runs.
