Resin Composition Adhesion to Low Roughness Copper Foil
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Solution Overview
Problem
Existing adhesive technologies face challenges in achieving strong adhesiveness to polyimide-based resin films and metallic foils with low surface roughness, particularly in high-density flexible printed boards, where adhesiveness and electrical insulation are critical but initial adhesion strength and anchor effects are compromised.
Innovation Solution
A resin composition comprising a modified hydrogenated block copolymer with an alkoxysilyl group and a crosslinking aid, specifically designed to enhance adhesiveness to polyimide-based resin films and metallic foils with low surface roughness, achieving strong bonding and improved electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a copper foil with low surface roughness is used to reduce transmission loss, then electrical insulation and signal quality are improved, but adhesiveness with the resin substrate deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive resin by incorporating specific functional groups (carboxylic acid groups with 0.01-5 mmol/g and hydroxyl groups with 0.01-5 mmol/g) into the polymer chain. This chemical modification enables the adhesive to form strong bonds with smooth copper surfaces through chemical interactions, resolving the adhesion problem without requiring surface roughness
Solution Approach 2:
The invention creates a composite adhesive system by combining multiple functional components: the base polymer matrix providing mechanical strength, carboxylic acid groups providing chemical bonding to copper, and hydroxyl groups providing additional bonding sites and humidity resistance. This multi-functional composite structure achieves both strong adhesion to smooth surfaces and environmental resistance
2Manufacturing precision
If the anchor effect is reduced due to roughening treatment removal, then transmission loss is reduced, but initial adhesion strength deteriorates
Solution Approach 1:
The invention replaces the mechanical anchoring mechanism (which relied on physical interlocking with rough surfaces) with a chemical bonding mechanism. The carboxylic acid and hydroxyl groups in the adhesive form chemical bonds with the copper surface and polyimide substrate, creating strong adhesion without requiring mechanical interlocking through surface roughness
3Reliability
If adhesiveness is improved through silane coupling agents and surface treatments, then environmental resistance is improved, but initial adhesion strength cannot compensate for anchor effect loss
Solution Approach 1:
The invention optimizes the functional group parameters within specific ranges (carboxylic acid: 0.01-5 mmol/g, hydroxyl: 0.01-5 mmol/g) to achieve the right balance between initial adhesion strength and environmental resistance. This parameter optimization ensures sufficient crosslinking density for humidity resistance while maintaining adequate initial bonding strength
Solution Approach 2:
The invention creates a multi-functional adhesive composite that simultaneously provides: (1) strong initial adhesion through multiple bonding mechanisms, (2) environmental resistance through crosslinked network structure, and (3) compatibility with both smooth copper and polyimide surfaces. This composite approach achieves all requirements without compromising initial adhesion strength
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 provides excellent adhesiveness and electrical insulation, enabling the production of high-density flexible printed boards with enhanced solder heat resistance and mechanical strength, even with metallic foils having low surface roughness.
Implementation Method 1
a modified hydrogenated block copolymer with an alkoxysilyl group
Implementation Method 2
a crosslinking aid
Data Source
AI summary
The present invention is a resin composition comprising a specific modified hydrogenated block copolymer [E] prepared by introducing an alkoxysilyl group and a crosslinking aid; a resin laminate prepared by laminating a layer including the resin composition on at least one side of a polyimide-based resin film; and a resin laminated metallic foil prepared by laminating a metallic foil on at least one side of the polyimide-based resin film through the layer including the resin composition. According to the present invention, provided are: a novel resin composition excellent in adhesiveness to a polyimide-based resin film and a metallic foil with low surface roughness and excellent in electrical insulation; a resin laminate prepared by laminating the resin composition and a polyimide-based resin film; and a resin laminated metallic foil that is useful for manufacturing a high density flexible printed board, in which the polyimide-based resin film and a metallic foil with a low surface roughness are laminated by using the resin composition as an adhesive.