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Method to Utilize Polyimides as Dielectrics for High Performance Multilayer Electronic Packaging Structures

IP.com Disclosure Number: IPCOM000107548D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Davis, CR: AUTHOR [+6]

Abstract

Polyimides, particularly low-stress types, possess unusual combinations of desirable characteristics, i.e., low dielectric constant, low coefficient of thermal expansion, and excellent thermal stability, that make them attractive as insulation layers for electronic device applications. Although such polyimides have found acceptance in the first-level packaging arena, they have had minimal impact in the second-level multilayer packaging. This can be attributed in part to the poor adhesion between two fully cured polyimide layers making fabrication of multilayer structures difficult.

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Method to Utilize Polyimides as Dielectrics for High Performance Multilayer Electronic Packaging Structures

       Polyimides, particularly low-stress types, possess
unusual combinations of desirable characteristics, i.e., low
dielectric constant, low coefficient of thermal expansion, and
excellent thermal stability, that make them attractive as insulation
layers for electronic device applications. Although such polyimides
have found acceptance in the first-level packaging arena, they have
had minimal impact in the second-level multilayer packaging.  This
can be attributed in part to the poor adhesion between two fully
cured polyimide layers making fabrication of multilayer structures
difficult. This article identifies materials, specifically, high
temperature polyimides having bulky substituents and flexible
moieties as adhesives, and processes for the fabrication of
multilayer structures where low-stress polyimides are utilized as the
major insulating material.

      As an example, a chromium-coated copper sheet is coated with a
solution of biphenyl tetracarboxylic dianhydride/phenylene diamine
(BPDA-PDA) polyamic acid which is available from E. I. du Pont de
Nemours & Co. as Pyralin 2610 and 2611. The coating's solvent is
partially removed by drying in a convection oven at a temperature and
time significantly below that where any appreciable imidization
occurs, for instance, 80 degrees C for 20 minutes.  A layer of
adhesive polyamic acid, such as,
4,4'-(hexafluoroisopropylidene)bis(phthalic anhydride)/oxydianiline,
available from E. I. du Pont de Nemours & Co. as Pyralin
2566(6FDA-ODA), or biphenyl-tetracarboxylic dianhydride/ 2,2-bis
[4...