Browse Prior Art Database

Non-hermetic Sealing Structure for Reworkable Multichip Module

IP.com Disclosure Number: IPCOM000122696D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 59K

Publishing Venue

IBM

Related People

Buchwalter, SL: AUTHOR [+2]

Abstract

Disclosed is a reworkable sealband structure for a surface-mount multichip module (MCM). Previous technology in non-hermetic sealing of single-chip modules did not allow for rework, as it was not cost effective. Current MCMs have substantially higher value in chips and circuitry, which requires the ability to rework the module, should one chip fail during burn-in, testing or actual use.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 87% of the total text.

Non-hermetic Sealing Structure for Reworkable Multichip Module

      Disclosed is a reworkable sealband structure for a
surface-mount multichip module (MCM).  Previous technology in
non-hermetic sealing of single-chip modules did not allow for rework,
as it was not cost effective.  Current MCMs have substantially higher
value in chips and circuitry, which requires the ability to rework
the module, should one chip fail during burn-in, testing or actual
use.

      To meet this new requirement, a condensation cure, pressure-
sensitive adhesive silicone is used as a non-hermetic sealband for
the MCM.  The sealband (silicone on both sides of a Kapton* carrier
film) is positioned onto a cap (aluminum or other common cap
material) via a pyramid (Figure 1).  The cap, with sealband, is then
positioned and sealed onto an MCM substrate (silicon, ceramic or
other similar material), as shown in Figure 2, and the assembly cured
for 3H/170C.  Due to the low modulus (< 200 psi) of the silicone
sealband, it absorbs any stress created by CTE mismatch between the
substrate and cap.

      After cure, the modules can survive elevated temperature and
humidity and temperature cycling stresses without device failures.
These sealed modules can easily be reworked in common ketones or
aromatic solvents at room temperature (e.g., MEK/3H/RT).  After
reseal and recure of the reworked modules, reliability is still
maintained.
*  Trademark of E. I. du Pont de Nemours & Co.

     ...