Results of assembly and reliability investigation of an MCM-L for an automotive application: electronic control unit

In the last year, MCMs have changed the view of electronic manufacturing due to novel functions. MCMs offer an attractive alternative to packaged components, as they increase packaging density and improve the reliability of electronic functions in a harsh environment. MCMs can increase manufacturability and, due to the use of low cost materials, they can save space, volume and weight in order to decrease overall costs. This paper shows the results of reliability tests carried out on test vehicles to optimise the manufacturing process. As base substrate materials, high T/sub g/ FR-4 and BT-epoxy was used to process the VLSIs on the MCM-L. The assembly was done using chip-on-board technology with chip-and-wire and flip-chip technology, showing the high performance of both methods. The paper presents current improvements to the substrate manufacturing process and fine pitch flip-chip bonding process. Different encapsulation technologies (glob top, underfilling, metal lid) are used to optimise reliability and media resistance for automotive requirements of harsh environment conditions for under-the-hood applications. Finally, the best technologies and processes, in terms of reliability performance and cost, have been selected to build the electrical demonstrator: an electronic control unit (ECU), which is briefly described.