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Low CTE Composite Substrate for Large Geometry Electronic Packages

IP.com Disclosure Number: IPCOM000010888D
Publication Date: 2003-Jan-29
Document File: 4 page(s) / 119K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses multiple CTE cores/layers, in combination with organic package substrate build-up layers, to reduce shear stresses between the materials. Other benefits include compatibility with conductive and non-conductive low CTE materials.

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Low CTE Composite Substrate for Large Geometry Electronic Packages

Disclosed is a method that uses multiple CTE cores/layers, in combination with organic package substrate build-up layers, to reduce shear stresses between the materials. Other benefits include compatibility with conductive and non-conductive low CTE materials.

Background

Current organic packaging applications that utilize low CTE layers consist of small openings to facilitate layer-to-layer signal routing.  At elevated temperatures, interfacial stresses between the two materials are created and can result in cracking. The current art is also limited in size due to the cracking that results in packages with larger distances from neutral point. 

Current development that corrects this issue is targeted at using alternative organic laminate/build-up layers that reduce the CTE mismatch between materials. Figure 4a shows the package at a low temperature where the laminate material has the same horizontal length as the lower CTE material.  As the temperature is increased (figure 4b) the laminate layer expands quicker than the low CTE layer. The top of the laminate expands while the bottom of the laminate is constrained by the coupling with the low CTE layer. This coupling results in interfacial shear stresses at elevated temperature ranges. This stress continues to increase as the distance from the neutral point increases.

General Description

The disclosed method uses gaps/trenches in layers of a low CTE package (see Figures 1, 2, 3 & 5) to provide a discontinuous interfacial plane. These gaps reduce inter...