Novolac Epoxy Resin Composition for Low Thermal Expansion
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Solution Overview
Problem
Current epoxy resin compositions, such as naphthol novolac type epoxy resins, fail to adequately meet the demands for high heat resistance, low thermal expansion, and low moisture absorption, leading to connection failures in printed wiring boards due to significant volume changes during thermal history.
Innovation Solution
A curable resin composition incorporating a cresol-naphthol co-condensed novolac type epoxy resin, a naphthol glycidyl ether compound, and a xanthene compound, with the xanthene content ranging from 0.1% to 5.5% by area ratio, which exhibits a small change in volume after thermal history, excellent low thermal expansion, and low moisture absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If naphthol novolac type epoxy resin is used to reduce thermal expansion, then thermal expansion coefficient is improved, but volume change during thermal history increases causing connection failure
Solution Approach 1:
The patent changes the chemical composition parameters of the epoxy resin by incorporating specific ratios of naphthol novolac type epoxy resin (5-20 mass%), phenolic hydroxy group-containing resin (75-90 mass%), and cycloaliphatic polyamine compound (5-20 mass%). This parameter optimization achieves both low thermal expansion coefficient (below 70 ppm/K) and small volume change after thermal history, resolving the contradiction between thermal expansion control and connection reliability
Solution Approach 2:
The patent creates a composite resin system by combining multiple resin components (naphthol novolac type epoxy resin, phenolic hydroxy group-containing resin) with a specific curing agent (cycloaliphatic polyamine compound). This composite approach leverages the complementary properties of each component to achieve both low thermal expansion and minimal volume change, preventing solder ball connection failures while maintaining dimensional stability
2Reliability
If reflow temperature is increased for lead-free solder, then solder clack resistance is improved, but volume change of insulating material increases causing warpage and connection failure
Solution Approach 1:
The patent optimizes the chemical composition parameters to achieve high heat resistance with decomposition temperature above 400°C while simultaneously controlling volume change after thermal history to below 3.0%. The specific ratio of cycloaliphatic polyamine compound (5-20 mass%) combined with phenolic hydroxy group-containing resin creates a crosslinked structure that resists thermal degradation and minimizes expansion, enabling solder clack resistance at high reflow temperatures without warpage or connection failure
Solution Approach 2:
The patent introduces local quality by selecting specific functional groups and molecular structures in the resin components. The phenolic hydroxy group-containing resin provides high-temperature stability and low moisture absorption, while the cycloaliphatic polyamine compound creates a crosslinked network that restricts molecular movement and reduces thermal expansion. This localized functional optimization enables the material to withstand high reflow temperatures with minimal volume change, maintaining connection reliability
3Volume of moving object
If naphthol novolac type epoxy resin is used to achieve low thermal expansion, then thermal expansion coefficient is reduced, but heat resistance and moisture absorption rate are insufficient
Solution Approach 1:
The patent creates a composite system combining naphthol novolac type epoxy resin (5-20 mass%) with phenolic hydroxy group-containing resin (75-90 mass%) and cycloaliphatic polyamine compound (5-20 mass%). This composite structure achieves low thermal expansion coefficient (below 70 ppm/K) while simultaneously providing high heat resistance (decomposition temperature above 400°C) and low moisture absorption (below 0.10 mass%). The synergistic interaction between components resolves the contradiction between thermal expansion control and heat resistance
Solution Approach 2:
The patent changes the chemical composition parameters by optimizing the ratios of resin components and curing agent. The phenolic hydroxy group-containing resin contributes high-temperature stability and low moisture absorption, while the cycloaliphatic polyamine compound creates a dense crosslinked structure that reduces thermal expansion and enhances heat resistance. This parameter optimization achieves all three targets: low thermal expansion, high heat resistance, and low moisture absorption simultaneously
Data Source
AI summary
An epoxy resin exhibits a small change in volume after thermal history, is excellent in low thermal expansion and low moisture absorption, and has high heat resistance, in terms of a cured product obtained therefrom; a curable resin composition; a cured product which has all the above properties; a semiconductor encapsulating material; a semiconductor device; a prepreg; a circuit board; a buildup film; a buildup substrate; a fiber-reinforced composite material; and a molded article. The present invention is characterized by an epoxy resin, characterized by including as essential components, a cresol-naphthol co-condensed novolac type epoxy resin (A), a naphthol glycidyl ether compound (B), and one or more xanthene compounds (C) selected from the group of compounds represented by the following structural formulae (1) to (3), wherein the content of the xanthene compound(s) (C) is from 0.1% to 5.5% in terms of area ratio in a GPC measurement.