Fundamentals of MCM testing and design-for-testability

Products motivated by performance-driven and/or density-driven goals often use Multi-Chip Module (MCM) technology, even though it still faces several challenging problems that need to be resolved before it becomes a widely adopted technology. Among its most challenging problems is achieving acceptable MCM assembly yields while meeting quality requirements. This problem can be significantly reduced by adopting adequate MCM test strategies: to guarantee the quality of incoming bare (unpackaged) dies prior to module assembly; to ensure the structural integrity and performance of assembled modules; and to help isolate the defective parts and apply the repair process. This paper describes today's MCM test problems and presents the corresponding test and design-for-testability (DFT) strategies used for bare dies, substrates, and assembled MCMs.