Modified Epoxy Resin CTE Reduction via Phase Separation
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Solution Overview
Problem
Epoxy materials used in semiconductor packaging exhibit high coefficient of thermal expansion (CTE), leading to warpage and cracking issues, which hinder processability and reliability in semiconductor packaging.
Innovation Solution
A modified novolac epoxy resin with specific weight average molecular weight (5,000 to 25,000) and polydispersity index (5.0 to 20.0) is developed, combined with a specific epoxy equivalent weight (150 g/Eq to 500 g/Eq), and used in conjunction with an acrylic resin to control phase separation characteristics, resulting in improved thermal expansion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy materials are used in semiconductor packaging, then adhesive properties and mechanical strength are improved, but coefficient of thermal expansion increases leading to warpage and cracking
Solution Approach 1:
The patent modifies the epoxy resin by controlling the average molecular weight (5,000 to 25,000) and polydispersity index (5.0 to 20.0) parameters. By adjusting these molecular parameters and the epoxy equivalent weight (150 to 500 g/Eq), the resin achieves optimized phase separation characteristics that reduce the coefficient of thermal expansion while preserving adhesive properties.
Solution Approach 2:
The patent creates a composite system by blending modified epoxy resin with acrylic resin. This composite approach leverages the complementary properties of both materials: the epoxy provides strength and adhesion while the acrylic contributes to stress relaxation and reduced thermal expansion, achieving a balance that neither material could achieve alone.
2Reliability
If acrylic resin is blended with epoxy resin to improve stress relaxation, then adhesive properties are enhanced, but phase separation occurs during curing
Solution Approach 1:
The patent controls the phase separation phenomenon by precisely adjusting the molecular weight parameters of the epoxy resin. The specific range of average molecular weight (5,000 to 25,000) and polydispersity index (5.0 to 20.0) creates optimal phase separation characteristics during curing, transforming an unwanted side effect into a controllable feature that enhances stress relaxation while maintaining composition stability.
3Adaptability or versatility
If semiconductor packaging is made highly integrated, thin, and large-area, then device functionality is improved, but warpage and cracking become more serious due to high CTE
Solution Approach 1:
The patent addresses the warpage and cracking issues in advanced semiconductor packaging by modifying the epoxy resin's molecular parameters. The controlled average molecular weight (5,000 to 25,000) and polydispersity index (5.0 to 20.0) create a material with reduced coefficient of thermal expansion, enabling highly integrated, thin, and large-area packages to maintain dimensional stability during thermal cycling without warpage or cracking.
Data Source
AI summary
The present disclosure relates to a modified epoxy resin having a weight average molecular weight of 5,000 to 25,000 and a polydispersity index of 5.0 to 20.0, and comprising (1) an epoxy-derived unit and (2) a modifier-derived unit, a preparation method thereof, a composition comprising the same, and uses thereof. When the epoxy composition comprising the modified epoxy resin according to the present disclosure is cured, the epoxy composition has a lowered coefficient of thermal expansion (CTE), i.e., improved thermal expansion properties, due to curing-induced phase separation (morphological properties) into an epoxy region and an acrylic region. The modified epoxy of the present disclosure and the epoxy composition comprising the same are suitable as adhesives for semiconductor packaging.