Statistical Tolerance Study Sample
Definition: Statistical analysis of minimum recommended target sizes, based on actual customer bare board manufacturing tolerances combined with Everett Charles Technologies advanced fixture customizing techniques.
The figure below identifies the maximum recommended target size for various types of ECT fixtures based on a false failure rate of approximately 50 parts per million (ppm) based on an actual STS.
The results provided in the figure are based on the following board manufacturing tolerances; +/- .004" on the location of the test target relative to the tooling hole, +/- .002" on the diameter of the test target and +/- .002" on the diameter of the tooling hole. ECT can perform tolerances studies to assess targeting accuracy for board manufacturing tolerances which differ from those listed above.