The economics of guardband placement

This paper investigates the guardbanding technique used with production test equipment. The consequences of guardband size and tester inaccuracy on the profit per unit produced are analyzed. The Taguchi loss function is used to model the effect of customer dissatisfaction when a product strays from its intended target. This loss function is integrated with product profitability and the variables of the test process. Sample computations are reported relating profits to the process capability index C_pk and to tester measurement error. The results show examples of when guardbands are beneficial, and how much benefit they provide