Hilaire Perera
February 22nd, 2009, 03:39 PM
Adaptive ESS is based on the adjustment of screens in response to previously observed screening results to minimize Outgoing Defects using the Chance Defective Exponential Model [ Failure Rate = A + B * EXP ( - C * t ), where t = Screening Time; A,B,C constants determined by curve fitting of failure data ].
In this way, the screens are always most cost effective while meeting the program goals with no unnecessary usage of Service Life. Given no failure mechanism/mode information, Random Vibration followed by Thermal Cycling is a good default screening condition
Test Strength [TS] = (Detection Efficiency [DE]) * ( 1 - EXP ( - C * t ))
Outgoing Defect Density [Dout] = ( B / C ) * ( 1 - TS )
Time to Remove 99.999% Defects = ( - 1 / C ) * ln (0.00001)
In this way, the screens are always most cost effective while meeting the program goals with no unnecessary usage of Service Life. Given no failure mechanism/mode information, Random Vibration followed by Thermal Cycling is a good default screening condition
Test Strength [TS] = (Detection Efficiency [DE]) * ( 1 - EXP ( - C * t ))
Outgoing Defect Density [Dout] = ( B / C ) * ( 1 - TS )
Time to Remove 99.999% Defects = ( - 1 / C ) * ln (0.00001)