FPC Adhesive Composition for Low-Dielectric Films and Copper Foil
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Solution Overview
Problem
Existing adhesive agents for flexible printed-wiring boards (FPCs) lack low dielectric properties, adhesion strength to low-dielectric resin films and copper foils, and moisture and reflow resistance, which are critical for high-frequency applications.
Innovation Solution
A composition comprising a maleimide compound with specific molecular weight and organic groups, an epoxy resin with multiple epoxy groups, a diaminotriazine ring-containing imidazole, and optionally an inorganic filler, which provides low dielectric properties, high adhesion strength, and moisture and reflow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy resin compositions or acrylic resin compositions are used as adhesive agents, then adhesion strength to copper foil and base material is improved, but dielectric properties deteriorate (transmission loss increases)
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive agent by using polyphenylene ether as the base resin and combining it with specific curing agents (isocyanate or polyfunctional silane) to achieve both low dielectric properties and sufficient adhesion strength. This parameter change resolves the contradiction by finding a material composition that simultaneously satisfies both requirements.
Solution Approach 2:
The patent creates a composite adhesive system by combining polyphenylene ether resin with specific curing agents (isocyanate or polyfunctional silane) and optionally with coupling agents. This composite material approach allows the adhesive to achieve both low dielectric properties from the polyphenylene ether and sufficient adhesion strength from the curing system, resolving the contradiction between these two properties.
2Loss of energy
If polyphenylene ether resin composition is used as low-dielectric material, then dielectric properties are improved, but adhesion strength deteriorates
Solution Approach 1:
The patent uses coupling agents (silane or isocyanate) as intermediary substances that bridge the polyphenylene ether resin and the substrate (copper foil or base material). These coupling agents chemically bond to both the resin and the substrate, providing the necessary adhesion strength while maintaining the low dielectric properties of the polyphenylene ether system.
Solution Approach 2:
The patent creates a composite adhesive system by combining polyphenylene ether resin with specific curing agents (isocyanate or polyfunctional silane) and optionally with coupling agents. This composite material approach allows the adhesive to achieve both low dielectric properties from the polyphenylene ether and sufficient adhesion strength from the curing system, resolving the contradiction between these two properties.
3Ease of manufacture
If conventional adhesive agents are used, then ease of manufacture is maintained, but moisture resistance and reflow resistance deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive agent by using polyphenylene ether as the base resin and combining it with specific curing agents (isocyanate or polyfunctional silane) to achieve both low dielectric properties and sufficient adhesion strength. This parameter change resolves the contradiction by finding a material composition that simultaneously satisfies both requirements.
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 composition achieves low dielectric properties, high adhesion strength to copper foil and low-dielectric resin films, and excellent moisture and reflow resistance, suitable for high-frequency applications.
Implementation Method 1
a maleimide compound having at least two maleimide groups in one molecule, having a number average molecular weight of greater than 4,000
Implementation Method 2
the maleimide compound being represented by the following general formula (1), wherein A independently represents a tetravalent organic group
Implementation Method 3
an epoxy resin having at least two epoxy groups in one molecule
Implementation Method 4
the epoxy resin and the maleimide compound to form a crosslinked network structure
Implementation Method 5
a diaminotriazine ring-containing imidazole
Implementation Method 6
an inorganic filler
Implementation Method 7
excellent moisture resistance and reflow resistance
Implementation Method 8
reflow resistance
Data Source
AI summary
Provided is an adhesive composition for a flexible printed-wiring board (FPC) that has low dielectric properties, a high adhesion strength to low-dielectric resin films (LCP or MPI) and a copper foil, and an excellent moisture resistance and reflow resistance. This adhesive composition contains:(A) 100 parts by mass of a maleimide compound having at least two maleimide groups in one molecule, having a number average molecular weight of greater than 4,000, and having at least one divalent organic group selected from a dimer acid skeleton, a linear alkylene group having not less than 6 carbon atoms, and a linear alkenylene group having not less than 6 carbon atoms;(B) 0.1 to 15 parts by mass of an epoxy resin having at least two epoxy groups in one molecule; and(C) 0.1 to 5 parts by mass of a diaminotriazine ring-containing imidazole.