Resin Composition for Wiring Boards Using Thermally Expandable Microcapsules
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Solution Overview
Problem
Conventional thermally expandable microcapsules used in foaming techniques for wiring boards have poor heat resistance, leading to impaired properties and unsuitable dielectric properties when exposed to curing temperatures above 100°C, limiting their application in wiring boards.
Innovation Solution
A resin composition combining a thermosetting resin with thermally expandable microcapsules, where the microcapsules have a maximum expansion temperature between 100°C and 280°C, maintaining heat resistance and achieving a relative dielectric constant of 1.0 to 2.2 in the cured product, enabling low dielectric properties and weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional thermally expandable microcapsules are used in thermosetting resin compositions, then the dielectric constant can be reduced, but the heat resistance deteriorates because the microcapsules burst during curing at temperatures above 100°C
Solution Approach 1:
The patent changes the key parameter of the microcapsule shell material from conventional polymers to polyether sulfone, which has a glass transition temperature of 185°C or higher. This parameter change enables the microcapsules to withstand curing temperatures above 100°C without bursting, while still maintaining the ability to expand and reduce the dielectric constant of the cured product to 2.2 or less.
2Quantity of substance
If thermoplastic resins are used for foaming to reduce dielectricity, then the dielectric constant can be lowered, but the application becomes complex and restricted due to requiring various hardware and having large expansion coefficients
Solution Approach 1:
The patent replaces the mechanical foaming process (requiring hardware and complex equipment) with a chemical foaming mechanism. The thermally expandable microcapsules contain a foaming agent that generates gas upon heating, creating foam structure automatically during the curing process without requiring external foaming equipment or complex mechanical systems.
3Quantity of substance
If conventional thermally expandable microcapsules are used, then the dielectric constant can be reduced, but the microcapsules cannot withstand curing temperatures and burst during the curing process
Solution Approach 1:
The patent changes the shell material parameter from conventional polymers with low glass transition temperatures to polyether sulfone with a glass transition temperature of 185°C or higher. This enables the microcapsules to maintain structural integrity at curing temperatures above 100°C while still expanding to reduce the dielectric constant of the final product.
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 resin composition effectively decreases the relative dielectric constant and maintains heat resistance, allowing for the production of lightweight wiring boards with excellent low dielectric properties and high heat resistance, suitable for electronic devices.
Implementation Method 1
thermally expandable microcapsules, in which a relative dielectric constant (10 GHz) of a cured product of the resin composition is more than 1.0 and 2.2 or less
Data Source
AI summary
A resin composition for wiring board material contains a thermosetting resin and a thermally expandable microcapsule, in which the relative dielectric constant (10 GHz) of a cured product of the resin composition is more than 1.0 and 2.2 or less.