Browse Prior Art Database

Engineering Change Method for Multilayer Ceramic/ Multichip Modules

IP.com Disclosure Number: IPCOM000108103D
Original Publication Date: 1992-Apr-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 100K

Publishing Venue

IBM

Related People

Frech, R: AUTHOR [+3]

Abstract

This article describes an engineering change (EC) method which changes only one (of 6) wiring planes.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Engineering Change Method for Multilayer Ceramic/ Multichip Modules

       This article describes an engineering change (EC) method
which changes only one (of 6) wiring planes.

      For multilayer ceramic (MLC) or glass ceramic multichip modules
(MCMs) of the next generation, the full EC pad capability on the top
surface of the substrate can no longer be retained, because of the
high I/O signal count per chip.

      This applies in particular to large CMOS (complementary metal
oxide semiconductor) chips.  Therefore, special probe pads have been
proposed and introduced which partially also allow ECs by adding
signals.

      Typical problems with which system designers are confronted
include logic design errors in the chip logic, on the chip-to-chip
connection of the MCM, and in connections from and to the chip and
the outside of the MCM.  Not all of these problems are detected by
system simulation and will appear during power-up or in subsequent
debugging phases, such as during the design verification test.  To
support EC pads for all signals would increase the substrate size and
drastically deteriorate the electrical characteristics. Therefore,
not all design errors can be fixed by the probe pad EC capability, so
that the chip(s) or the substrate of the MCM may have to be
redesigned.

      Redesigning the MCM requires long turn-around times at the
manufacturing location, as a number of process steps are involved.
Only the fixed layers which are on stock do not have to be rebuilt.
For future MLCs or MCMs comprising a larger number of plane pairs
(e.g. > 6, see the figure), the turn-around times will be
particularly long.

      The above-described ECs normally impact clock and control
lines.  It very rarely happens that buses have to be redesigned as
well.  Th...