Detecting Changes in Field Reliability Using Data from a Complex Factory Screen

Abstract

New products are sometimes screened in the factory before shipment to the field. We show how to use failure time data from one of these screens to predict early field reliability. These reliability predictions are more economical and timely than reliability estimates that wait for data from field tracking studies. Further, these predictions are continuously responsive to the changes in reliability that frequently occur during the manufacture of a new product, and therefore, can form the basis of a rapid-feedback system for manufacturing process control.

Keywords:

• maximum likelihood estimation
• delta method
• statistical process control
• reliability estimation

Notes

 ^aIn our application of the model, we have: k = 9, h = 8, (t₁, t₂, ,… ,t₉) = (4, 8, ,… , 36), (S₁, S₂, … ,S₈) = (5, 10, … , 40), and r = 4.