Styrene Elastomer Adhesive Composition for PCB Folding Endurance
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Solution Overview
Problem
Conventional printed wiring boards face challenges with high dielectric properties, poor folding endurance, and insufficient heat resistance due to the use of polyphenyleneether materials, which lack flexibility and have high melting points.
Innovation Solution
An adhesive composition comprising 70 to 90 parts by mass of styrene elastomer, 5 to 25 parts by mass of modified polyphenyleneether resin with a radical polymerizable group, and up to 10 parts by mass of epoxy resin and peroxide, with a styrene ratio of 42% or less, is used to create a thermosetting adhesive sheet for printed wiring boards, enhancing dielectric properties and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyphenyleneether is used as substrate material to achieve low dielectric properties, then dielectric constant and dielectric loss tangent are reduced, but folding endurance becomes inferior due to high melting point and hard property
Solution Approach 1:
The invention uses a composite material system consisting of polyphenyleneether resin (for low dielectric properties) combined with styrene elastomer (for flexibility and folding endurance) and modified polyphenyleneether resin with radical polymerizable groups (for crosslinking). This composite approach allows simultaneous achievement of low dielectric constant, low dielectric loss tangent, and excellent folding endurance by combining materials with complementary properties.
Solution Approach 2:
The invention changes the physical and chemical parameters of the material system by controlling the glass transition temperature (Tg) through specific composition ratios (polyphenyleneether 30-70 parts, styrene elastomer 10-40 parts, modified polyphenyleneether 5-20 parts) and implementing crosslinking reactions. This parameter optimization enables the material to maintain flexibility for folding while preserving low dielectric properties.
2Reliability
If polyphenyleneether is used to achieve low dielectric properties, then dielectric performance is improved, but heat resistance becomes insufficient for mounting components
Solution Approach 1:
The invention raises the glass transition temperature (Tg) to 80°C or higher through controlled crosslinking reactions of the modified polyphenyleneether resin with peroxide. This parameter change enables the material to withstand high temperatures during component mounting (solder reflow process) and hot bar solder processes while maintaining low dielectric properties for high-frequency applications.
Solution Approach 2:
The invention introduces local crosslinked structures within the adhesive composition through peroxide-cured crosslinking of radical polymerizable groups on polyphenyleneether chains. These localized crosslinked regions provide heat resistance and structural stability without compromising the overall low dielectric properties of the polyphenyleneether-based material system.
3Temperature
If conventional adhesive composition is used to achieve heat resistance, then heat resistance is improved, but dielectric properties and folding endurance deteriorate
Solution Approach 1:
The invention creates a specialized composite adhesive composition where polyphenyleneether resin (providing low dielectric properties) is combined with styrene elastomer (providing flexibility) and modified polyphenyleneether with crosslinkable groups (providing heat resistance through crosslinking). This composite formulation achieves simultaneous optimization of dielectric properties, folding endurance, and heat resistance, unlike conventional single-material or simple mixture adhesives.
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 achieves a low dielectric constant, low dielectric loss tangent, excellent folding endurance, and superior heat resistance, making it suitable for high-frequency applications and flexible printed wiring boards.
Implementation Method 1
a modified polyphenyleneether resin having a radical polymerizable group at an end; a peroxide
Implementation Method 2
the styrene elastomer has a functional group for promoting the curing reaction of the epoxy resin
Data Source
AI summary
An adhesive composition having a low dielectric constant, low dielectric loss tangent, excellent folding endurance, and excellent heat resistance. The adhesive composition includes: with respect to the total of 100 parts by mass of the adhesive composition, 70 to 90 parts by mass of the styrene elastomer; 5 to 25 parts by mass of a modified polyphenyleneether resin having a polymerizable group at an end; 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 42%.