Fluororesin Coating Composition for Low-Dielectric Adhesive Laminates
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Solution Overview
Problem
Existing coating compositions for circuit boards face challenges in achieving low coefficient of linear expansion, low dielectricity, excellent adhesive properties on smooth surfaces, and minimizing coating film defects such as cracks and holes.
Innovation Solution
A coating composition comprising 2 or more kinds of fluororesin dispersions, where at least one fluororesin has 30 to 1,000 functional groups per 10^6 main-chain carbon atoms, combined with an anisotropic filler, a surfactant, and a liquid medium, is used to form a coating film with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluororesin dispersion with low functional group content is used, then low dielectricity is achieved, but adhesive properties deteriorate
Solution Approach 1:
The patent changes the parameter of functional group content in fluororesin from low (conventional) to specifically 30-1,000 per 10^6 main-chain carbon atoms. This parameter optimization enables the resin to achieve both low dielectricity and excellent adhesive properties by balancing the fluorine content for low dielectric constant with sufficient functional groups for adhesion to copper foil and other substrates.
Solution Approach 2:
The patent uses composite fluororesin dispersions containing multiple fluororesin types with different functional group contents. By combining fluororesins with complementary properties, the composition achieves synergistic effects where the composite material provides both low dielectric constant and high adhesion that neither component could achieve alone.
2Reliability
If coating composition is applied to smooth copper foil surface, then excellent adhesive properties are achieved, but coating film defects such as cracks and holes occur
Solution Approach 1:
The patent optimizes multiple parameters including functional group content (30-1,000 per 10^6 main-chain carbon atoms), dispersion viscosity, and filler content. These parameter changes enable the coating to achieve proper wetting and adhesion on smooth surfaces while maintaining film integrity during drying and curing, preventing cracks and holes.
Solution Approach 2:
The patent introduces surfactants and dispersants as intermediary substances that mediate between the coating composition and the smooth copper foil surface. These intermediaries improve wetting and adhesion on smooth surfaces without causing film defects, acting as a bridge that enables reliable coating formation.
3Stability of the object's composition
If conventional fluororesin composition is used, then low coefficient of linear expansion is achieved, but adhesive properties on smooth surfaces deteriorate
Solution Approach 1:
The patent specifically optimizes the functional group content parameter to 30-1,000 per 10^6 main-chain carbon atoms, which maintains the low coefficient of linear expansion characteristic of fluororesins while dramatically improving adhesive properties. This precise parameter control resolves the contradiction between dimensional stability and adhesion.
Solution Approach 2:
The patent introduces functional groups at specific locations (local regions) of the fluororesin chains. These localized functional groups provide adhesion sites without altering the overall fluororesin structure and its low thermal expansion properties, achieving both low coefficient of linear expansion and good adhesion.
Data Source
AI summary
Provided is a coating composition capable of forming a coating film layer, which has low coefficient of linear expansion at low dielectricity, excellent adhesive properties even when the surface of a counterpart material is smooth, and few coating film defects such as cracks and holes. A coating composition including 2 or more kinds of fluororesin emulsions, wherein at least 1 kind of the fluororesin, a fluororesin (I), has a number of functional groups of 30 to 1,000 per 106 main-chain carbon atoms, and the coating composition further includes an anisotropic filler, a surfactant, and a liquid medium.