Browse Prior Art Database

Densely Populated, Vertically Stacked Multi Chip Module

IP.com Disclosure Number: IPCOM000115236D
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 95K

Publishing Venue

IBM

Related People

Reynolds, SD: AUTHOR [+2]

Abstract

This disclosure describes a technique to achieve very high electronic packaging densities for a multichip module used in a wide range of applications.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 59% of the total text.

Densely Populated, Vertically Stacked Multi Chip Module

      This disclosure describes a technique to achieve very high
electronic packaging densities for a multichip module used in a wide
range of applications.

      The preferred embodiment of this disclosure would entail the
use of several large silicon metallized chip carriers, each populated
with a plurality of semiconductor chips.  The carriers would each be
of different size, starting with the largest at the bottom and
working up to the smallest at the top of the stack.  Each carrier is
separated from the carrier below via a hard, controlled height
spacer.  Communication and electrical power is maintained through the
use of small flex cable/TAB like lead frames bonded to the carrier
edges via soldered or thermocompression joints (Figs. 1A and 1B).

The lead frames are electrically connected to the carrier directly
below.  As an alternative to silicon carriers, FR4 material (or
equivalent) may be used in conjunction with a suitable encapsulant to
prevent C4 damage during thermal cycling.  For better cooling, one
edge of each carrier may be extended into an air stream or connected
to a finned array heat sink (Fig. 2).  Another embodiment of the
scheme would use metal plates (copper/ aluminum) over which a
metalized flex cable is bonded and extends beyond the edge of the
carriers to form the lead frame interconnection.  The flex cables
would include multiple chip sites (square holes in the plastic) where...