Major Circuit Yield Improvement: Yours for the Price of Minor Resistor Redesign

A method has been developed to optimize thick film resistor geometries for maximum manufacturing yield by utilizing the mathematics of the normal distribution curve. Use of the method introduces minor changes in registor geometry to increase the size of the manufacturing window, and thereby to greatly reduce the number of reject circuits. The optimization method is described with examples from an actual redesign of a heart Pacer thick film circuit. Sample calculations are made and tables are shown giving complete results for selected resistors. Production yield results are given for the heart pacer circuit. These results show that large yield improvements were in fact achieved on a difficult circuit by use of this Optimization method.