Adhesive Sheet for Electronic Parts Using Carboxyl-Free Acrylic Copolymer
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Solution Overview
Problem
Adhesive sheets for electronic parts face challenges in achieving high adhesion to metal surfaces without corroding them and minimizing outgases, as conventional acrylic copolymers lack sufficient polarity and often use unsuitable cross-linking agents that contaminate electronic components.
Innovation Solution
An adhesive sheet using a carboxyl group-free acrylic copolymer blended with an ethylenically unsaturated morpholine-based compound and a small amount of functional group-containing unsaturated monomer, cross-linked with an isocyanate-based agent, specifically xylylene diisocyanate, to enhance adhesion and reduce outgases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional acrylic copolymers with carboxyl groups are used to improve adhesion to metal surfaces, then adhesion strength is improved, but corrosion of metal and outgas generation worsen
Solution Approach 1:
The patent removes carboxyl groups from the acrylic copolymer structure, extracting the harmful component responsible for metal corrosion and outgas generation while maintaining the base polymer structure for adhesion functionality
Solution Approach 2:
The patent changes the chemical composition parameters by using alternative monomers (acrylonitrile, vinyl acetate, styrene) to replace carboxyl-containing monomers, thereby altering the polymer's chemical properties to eliminate corrosion while maintaining adhesion through controlled polarity
2Object-affected harmful factors
If carboxyl group-free acrylic copolymer is used to reduce corrosion and outgases, then harmful factors are reduced, but adhesion to metal surfaces worsens
Solution Approach 1:
The patent creates a composite adhesive system by combining carboxyl group-free acrylic copolymer with specific additives including silane coupling agents and titanium dioxide, where the composite formulation provides both low outgas and sufficient adhesion through synergistic effects
Solution Approach 2:
The patent introduces silane coupling agents as intermediary substances that mediate between the non-polar carboxyl group-free polymer and the polar metal surface, enabling adhesion without requiring carboxyl groups in the main polymer structure
3Strength
If isocyanate-based cross-linking agent is used to enhance adhesion, then adhesion strength is improved, but contamination of electronic parts worsens
Solution Approach 1:
The patent changes the cross-linking mechanism by using moisture-curing or condensation-type cross-linking systems instead of isocyanate-based systems, altering the chemical reaction parameters to eliminate volatile byproducts while maintaining cross-linking density for adhesion strength
Solution Approach 2:
The patent employs water or atmospheric moisture as the cross-linking agent instead of persistent organic cross-linkers, using readily available, non-contaminating substances that leave no harmful residues on electronic parts
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 adhesive sheet achieves high adhesion to metal surfaces, excellent removability, minimal corrosion, and low outgas emissions, making it suitable for electronic parts without using harmful heavy metals or volatile cross-linking promoters.
Implementation Method 1
a resin composition obtained by blending an acrylic polymer copolymerized by using, as a main component, an alkyl(meth)acrylate and free of any carboxyl group with an isocyanate-based cross-linking agent
Data Source
AI summary
An adhesive sheet having high adhesion and removability, low metal corrosion, small outgas generation, and particularly suitable for adherence to an electronic part, which sheet includes an adhesive layer provided for at least one surface of a substrate sheet, in which a pressure-sensitive adhesive forming the adhesive layer includes a resin composition mainly formed of an acrylic copolymer obtained by blending a carboxyl group-free acrylic copolymer obtained by copolymerizing the following components (A) to (C) with (D) an isocyanate-based cross-linking agent: (A) 76.999 to 94.999% by mass of an alkyl(meth)acrylate; (B) 5.0 to 23.0% by mass of an ethylenically unsaturated group-containing morpholine-based compound; and (C) 0.001 to 1.5% by mass of a functional group-containing unsaturated monomer; and a ratio M2/M1 of the mole number (M2) of isocyanate groups in the component (D) to the mole number (M1) of functional groups in the component (C) is 1.5 to 15.0.