An empirical relationship between test transparency and fault coverage

The concept of test transparency was used to analyze the reject data from different fault coverage soft bins. The device used in the study was a gate array with 12.5 K equivalent logic gates. As additional vectors were generated they were isolated into separate modules within the sort program. The sort program shell was altered to provide a soft bin count of the number of failures incurred within each module. This information was then uploaded automatically into the manufacturing database. The results presented are based on functional test results from over 350000 dice. It is shown that Boolean testing can be represented as a linear relationship between test transparency and fault coverage. The linear coefficients are sensitive to the defect type for the stuck-at model fault coverage. The linear coefficients are also sensitive to the fault vector generation methodology