Halogen-Free Epoxy Adhesive Resolves Phase Separation
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Solution Overview
Problem
Conventional adhesive agents used in multi-layered flexible printed circuit boards and IC packaging, such as acrylic resin and epoxy resin, exhibit poor thermal and chemical resistance, and blending with bismaleimide results in a brittle mixture that cannot be coated homogeneously due to phase separation, with residual high boiling point solvents degrading electronic device quality.
Innovation Solution
A halogen-free and thermal resistant composition comprising a mixture of bismaleimide and maleimide in a 99:1 to 50:50 molar ratio, barbituric acid in a 93:7 to 80:20 molar ratio, and epoxy resin in a 5:95 to 50:50 weight ratio, which forms an interpenetrating copolymer without the need for high boiling point solvents, enhancing thermal resistance and solubility while eliminating phase separation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bismaleimide is blended with epoxy resin to improve thermal and chemical resistance, then thermal resistance and chemical resistance are improved, but the mixture becomes brittle and cannot be coated homogeneously due to phase separation
Solution Approach 1:
The patent introduces a specific polyfunctional amine compound as an intermediary coupling agent between bismaleimide and epoxy resin. This amine compound has multiple reactive groups that can react with both bismaleimide and epoxy resin, forming a bridging structure that prevents phase separation and ensures homogeneous mixing while maintaining the thermal and chemical resistance benefits of bismaleimide.
Solution Approach 2:
The patent creates a composite adhesive system comprising epoxy resin, bismaleimide, and a polyfunctional amine compound in specific proportions. This composite formulation leverages the complementary properties of each component: epoxy resin provides baseline adhesion and flexibility, bismaleimide enhances thermal and chemical resistance, and the polyfunctional amine ensures homogeneous integration of all components, eliminating phase separation.
2Ease of manufacture
If high boiling point solvent such as γ-butyrolactone is used for polymerization, then the adhesive composition can be processed, but the solvent cannot be fully removed and residues degrade the quality of electronic devices
Solution Approach 1:
The patent eliminates the harmful high boiling point solvent (γ-butyrolactone) from the adhesive composition entirely. Instead, it uses a solvent-free formulation where the polyfunctional amine compound acts as both the curing agent and the processing medium, allowing the adhesive to be applied and cured without introducing any removable solvent that could leave degrading residues.
Solution Approach 2:
The polyfunctional amine compound serves multiple functions simultaneously: it acts as the curing agent for polymerization, as the processing medium that enables application of the adhesive, and as part of the final cured structure. This self-service approach eliminates the need for a separate solvent that would need to be removed, avoiding residue problems entirely.
3Ease of operation
If acrylic resin or epoxy resin is used as adhesive agent, then the adhesive can be applied easily, but thermal and chemical resistance properties are poor compared to polyimide
Solution Approach 1:
The patent merges the advantages of different resin systems by combining epoxy resin (which provides good applicability and adhesion) with bismaleimide (which provides superior thermal and chemical resistance). The polyfunctional amine compound facilitates the integration of these components, creating a unified adhesive system that exhibits both ease of application and enhanced thermal/chemical resistance, achieving properties comparable to or exceeding polyimide while maintaining epoxy-based processability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition provides improved thermal resistance, chemical resistance, and peeling strength, with reduced curing temperature and simplified manufacturing, forming high-quality, bubble-free materials suitable for electronic packaging applications.
Implementation Method 1
The polymerization of the composition requires a high boiling point solvent such as γ-butyrolactone that cannot be fully removed after polymerization
Implementation Method 2
a halogen-free and thermal resistant composition comprising a mixture of bismaleimide and maleimide... and an epoxy resin
Data Source
AI summary
The invention provides a halogen-free and thermal resistant composition, including a mixture of bismaleimide and maleimide with molar ratio of 99:1-50:50; a barbituric acid, wherein the molar ratio of the mixture and the barbituric acid is 93:7-80:20; and an epoxy resin, wherein (the mixture with the barbituric acid) and the epoxy resin have a weight ratio of 5:95 to 50:50. The mixture undergoes reaction at 110-130° C. for about 2˜7 hours to form a maleimide modified epoxy resin. The procedure of forming the composition is solvent-free, thereby providing improved integrity for electronic packaging, lower curing temperature, and a simplified process.