Styrene Elastomer Adhesive for Low Dielectric PCBs
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Solution Overview
Problem
Conventional adhesive compositions for printed wiring boards face challenges in achieving low dielectric constants, low dielectric loss tangents, and sufficient folding endurance, particularly with polyphenyleneether materials that have high melting points and hard properties at ordinary temperatures.
Innovation Solution
An adhesive composition comprising 75 to 90 parts by mass of styrene elastomer, 3 to 25 parts by mass of modified polyphenyleneether resin with a polymerizable group, and 10 parts by mass or less of epoxy resin and curing agent, with a styrene ratio less than 30%, forming a thermosetting adhesive sheet for printed wiring boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If polyphenyleneether is used as the main resin component (30-50% composition) to achieve low dielectric properties, then the dielectric constant and dielectric loss tangent are reduced, but the folding endurance deteriorates due to high melting point and hard properties
Solution Approach 1:
The patent changes the chemical composition parameters by limiting polyphenyleneether to 5-30 mass% (down from conventional 30-50%) and introducing modified polyphenyleneether resin with polymerizable groups (10-40 mass%). This parameter change reduces the hard and brittle characteristics while maintaining low dielectric properties, thereby improving folding endurance
Solution Approach 2:
The patent creates a composite adhesive composition combining multiple resin systems: styrene-based resin (50-90 mass%) for flexibility and folding endurance, modified polyphenyleneether resin (10-40 mass%) for low dielectric properties, and epoxy resin (5-20 mass%) for adhesion. This composite approach balances dielectric performance with mechanical flexibility
2Loss of energy
If polyphenyleneether content is increased to achieve low dielectric constant, then the dielectric constant is reduced, but the material becomes too hard and brittle at ordinary temperature
Solution Approach 1:
The patent adjusts the polyphenyleneether content parameter to 5-30 mass% (reduced from conventional levels) and modifies it by introducing polymerizable groups through reaction with compounds containing vinyl or acrylic groups. This creates a balance between maintaining low dielectric constant and preserving flexibility at ordinary temperatures
Solution Approach 2:
The patent introduces modified polyphenyleneether resin as an intermediary component that combines the low dielectric constant benefit of polyphenyleneether with improved flexibility. The polymerizable groups allow it to participate in crosslinking while the modified structure maintains softer characteristics compared to conventional polyphenyleneether
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 solution provides a printed wiring board with low dielectric constants, low dielectric loss tangents, and excellent folding endurance by adjusting the glass transition temperature of the cured adhesive composition to a range of −40 to 40°C, enhancing peel strength, heat resistance, and storability.
Implementation Method 1
a modified polyphenyleneether resin having a polymerizable group at an end
Implementation Method 2
a cured product of the adhesive composition
Data Source
AI summary
An adhesive composition has a low dielectric constant, a low dielectric loss tangent, and an excellent folding endurance. The adhesive composition includes: with respect to the total of 100 parts by mass of the adhesive composition, 75 to 90 parts by mass of a styrene elastomer; 3 to 25 parts by mass of a modified polyphenyleneether resin having a polymerizable group at an end; and totally 10 parts by mass or less of an epoxy resin and an epoxy resin curing agent, wherein the styrene ratio of the styrene elastomer is less than 30%.