A MULTIPROBE APPROACH FOR MCM SUBSTRATE TESTING

Multi-chip module (MCM) technology has become an important means to pa ckage high performance systems. An important task during the packaging process is to check for possible open, short, and high resistance fau lts in the wiring networks of the bare MCM substrates, which is called substrate testing. After examining several substrate testing methodol ogies, we find that multi-probe or kappa-probe testers are cost-effect ive for substrate testing. However, the testing speed of this method i s not high; hence, we focus on improving the throughput by reducing th e number of tests and by deriving good probe routes. For test size red uction, we propose a routing tree model to capture the wiring structur e of a given net; then by taking advantage of the routing tree, we gen erate a minimum number of tests while ensuring complete open fault cov erage. Our algorithm reduces the number of tests by up to 50% compared to that of previous approaches. Given a routing tree with its node de gree bounded by a constant, our test generation algorithm runs in line ar time with respect to the number of leaves of the tree. For probe ro ute scheduling, we observe that in order to obtain a balanced and effi cient scheduling, the routes of different probes must be considered si multaneously, which motivates our Multi-Dimensional Traveling Salesman Problem (MDTSP) formulation. Our package has been installed on existi ng substrate testers and has achieved encouraging results.