Efficient smart substrates with test capabilities and on-line temperature monitoring

A methodology for testing active MCM silicon-based substrates by using boundary scan elements integrated into the carrier is presented. By optimizing the scan cell organization, the test circuitry causes no degradation of signal propagation. Tests of the bare substrate and of the assembled carrier can be accomplished efficiently. To monitor substrate and chip temperature, an on-line monitoring system is integrated into the substrate. The system is compensated for supply voltage variations and is calibrated to offset fabrication process deviations. An experimental carrier is fabricated