Heat-Curable Resin Composition for Smooth Copper Foil Adhesion
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Solution Overview
Problem
Existing heat-curable resin compositions face challenges in achieving low dielectric tangent and adhesivity, particularly when used with copper foils of low surface roughness, leading to resin peeling during the desmear process.
Innovation Solution
A heat-curable resin composition comprising aromatic and aliphatic cyclic imide compounds, epoxy resin, curing agent, and inorganic filler, with specific molecular weights and ratios, to enhance adhesivity and desmear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the surface roughness of copper foil is reduced to lower conductor loss, then transmission loss is reduced, but adhesivity between resin and copper foil decreases causing resin peeling during desmear process
Solution Approach 1:
The patent modifies the chemical composition parameters of the resin by incorporating specific maleimide compounds (20-80 wt%) with particular molecular structures and weight average molecular weights (5,000-100,000). This chemical parameter change enables the resin to maintain strong adhesivity to smooth copper foil surfaces while preventing peeling during desmear processing, thus resolving the contradiction between low conductor loss and reliable adhesion.
Solution Approach 2:
The patent creates a composite resin system combining maleimide compounds with epoxy resins and curing agents. This composite material approach leverages the complementary properties of each component: maleimide compounds provide excellent adhesion to copper and desmear resistance, while epoxy resins contribute to overall mechanical strength and electrical insulation, thereby achieving both low conductor loss and high reliability simultaneously.
2Reliability
If specific maleimide compound is used to improve dielectric properties and adhesion, then dielectric tangent is reduced and adhesion to metal is enhanced, but resin overly melts in desmear process causing peeling
Solution Approach 1:
The patent precisely controls the weight average molecular weight of maleimide compounds within 5,000-100,000 and specifies their content (20-80 wt%). This parameter optimization ensures the resin has appropriate melting characteristics that prevent excessive softening during desmear processing while maintaining excellent dielectric properties and metal adhesion, thus resolving the contradiction between reliability and desmear resistance.
Solution Approach 2:
The patent creates local quality differentiation within the resin system by having maleimide compounds concentrate at the copper foil interface to provide strong adhesion and dielectric performance, while the bulk resin matrix (containing epoxy and curing agents) provides structural integrity and resistance to desmear etching. This spatial differentiation of functional properties resolves the contradiction between interface adhesion and bulk desmear resistance.
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 low dielectric tangent and excellent adhesivity, providing robust desmear resistance and suitable for bonding films, prepregs, copper foils, and build-up films, especially for high-speed communication applications.
Implementation Method 1
heat-curable resin composition comprising (A) an aromatic cyclic imide compound, (B) an aliphatic cyclic imide compound, (C) an epoxy resin, (D) a curing agent for epoxy resin
Implementation Method 2
exhibits an excellent adhesion force to metals or the like compared to epoxy resins and is a heat-curable resin
Implementation Method 3
particularly results in a cured product which exhibits an excellent desmear resistance (resistance against etching liquid)
Data Source
AI summary
Provided is a heat-curable resin composition that not only has a low dielectric tangent but also is excellent in adhesivity, and that particularly results in a cured product which exhibits an excellent desmear resistance. The heat-curable resin composition includes (A) an aromatic cyclic imide compound having a weight average molecular weight of 5,000 to 100,000, (B) an aliphatic cyclic imide compound having a weight average molecular weight of 100 to 2,000, (C) an epoxy resin having two or more epoxy groups in one molecule, (D) a curing agent for epoxy resin, (E) a curing catalyst, and (F) an inorganic filler, wherein the heat-curable resin composition contains the components (A) to (E) in a total amount of 5 to 99% by mass based on the overall composition.