Optimized wafer-probe and assembled package test design for analog circuits

Abstract

It is well known that wafer-probe test costs of analog ICs are an order of magnitude less than the corresponding test costs of assembled packages. It is therefore natural to push as much of the testing process into wafer-probe testing as possible to reduce the scope of assembled package testing. However, the signal drive and response observation capabilities during wafer probe testing are limited in comparison to assembled packages. In this article, it is shown that by using band-limited transient test signals, which can be supported by wafer-probe test instrumentation, significant numbers of bad ICs can be detected early during the wafer-probe test. The optimal test stimuli are determined by cooptimizing the wafer-probe and assembled package test waveforms. Overall test costs, including the cost of packaging bad ICs, are minimized and are reduced up to four times. The proposed method has been validated using hardware test data, which were obtained through measurements made on a prototype.