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Screening Test of Multichip Module Without Recalculation of Serial Number Dependent Test Values

IP.com Disclosure Number: IPCOM000084217D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 92K

Publishing Venue

IBM

Related People

Barbash, WA: AUTHOR

Abstract

Because of the repair status of a multichip module, it is improbable that modules with the same part number will have the same nets to chip-in-place test (CIPT). The screening tests prior to CIPT can be done without recalculation of the expected measurement values for each serial number of the module.

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Screening Test of Multichip Module Without Recalculation of Serial Number Dependent Test Values

Because of the repair status of a multichip module, it is improbable that modules with the same part number will have the same nets to chip-in-place test (CIPT). The screening tests prior to CIPT can be done without recalculation of the expected measurement values for each serial number of the module.

Prior to chip-in-place test (CIPT) of a multichip module (MCM), the MCM can be screened for gross degradation resulting from chip mounting. The following tests can presently be done without placing the MCM in a cooling environment as required for CIPT: 1) nodal conductance with low power applied, 2) impedance measurement with power off.

A problem arises with these tests in that the measurements to be made on the tested MCM are serial-number dependent, because of the repairs that must be made to the module substrate. The repair wires that do not affect CIPT are applied after CIPT. However, the measurements to be made in either Test 1 or 2 are dependent upon the net configuration, as seen at any chip-to-substrate connection redistribution pad (EC pad).

The expected measurements can be pre-computed for each serial number by examining the design and repair history files, and calculating the loading for the actual connections.

It is proposed that the calculation of the loading be eliminated and, in its place, that comparative measurements be made on a module Unit Under Test (U...