Investigation of design and performance of multichip modules including electromagnetic compatibility

This paper examines the effectiveness of EMI driven MCM substrate routing in reducing coupled noise in the MCM and subsequently on the motherboard. Different layouts of a three chip, laminate MCM were performed with and without EMI driven routing constraints. Quantic Labs EMC software was then used to simulate the crosstalk on critical nets for the different routings. It is shown that proper routing constraints can greatly reduce noise on susceptible nets and reduce noise on all nets in general. A software package to automatically generate router constraints base on EMI considerations is being developed to simplify the routing process. For experimental validation of the Quantic software, simple test structures were fabricated, tested and compared to simulation predictions. Also, a comparison of the coupled noise on the motherboard with an MCM versus three individual surface mount packages shows that the MCM significantly reduces the conducted emissions at the system level. Effective design of automotive MCM's with proper consideration to EMI requirements can substantially reduce conducted emissions from an engine controller unit onto the wiring harness. This results in improved system performance and potentially lower cost by eliminating EMI filtering components.