A MCM test strategy using boundary scan-cells integrated into silicon substrates is presented. The differences between IC-based boundary scan and active substrate boundary scan and their eflects on scan-cell placement and design are highlighted. A yield optimized partition of the test circuitry and an adaption to commercially available boundary scan testsystems is proposed. Active substrates with boundary scan test capabilities are fabricated based on the identified requirements. The adaption to the test system is evaluated.