Resin Composition for Ultra-Thin Copper Foil Adhesion
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Solution Overview
Problem
The existing fabrication processes for printed circuit boards using ultra-thin copper foils face challenges such as roughness changes and weakened adhesion, leading to poor peel strength between the copper foils and insulation resin layers, especially after thermal treatments like reflow, which affects the overall performance and reliability of the circuits.
Innovation Solution
An assembly comprising an ultra-thin copper foil with a thickness of less than or equal to 6 μm, combined with an insulation material made from a resin composition comprising oxazolidone epoxy resin, oxydianiline type benzoxazine resin, and a curing agent, which achieves a peel strength of greater than or equal to 3.0 lb/in and maintains excellent physical and chemical properties, including high glass transition temperature, low dimensional change after reflow, and improved thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ultra-thin copper foil is used to achieve fine lines and narrow spacing, then manufacturing precision is improved, but adhesion strength deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the resin system by using a specific combination of epoxy resin, phenolic resin, and polyimide resin in defined weight ratios. This parameter change in material composition improves the adhesion strength to ultra-thin copper foil while maintaining the ability to form fine lines and narrow spacing.
Solution Approach 2:
The patent employs a composite resin system comprising epoxy resin (30-70 wt%), phenolic resin (10-40 wt%), and polyimide resin (5-20 wt%). This composite material approach combines the advantages of different resins to achieve both strong adhesion to ultra-thin copper foil and suitable properties for fine line fabrication.
2Ease of manufacture
If thermal treatment is applied to process the circuit board, then manufacturing capability is improved, but adhesion strength deteriorates
Solution Approach 1:
The patent modifies the resin composition parameters to include heat-resistant components (phenolic resin and polyimide resin) that maintain adhesion properties after thermal treatment. The specific weight ratios of these resins are optimized to withstand reflow temperatures while preserving bonding strength to ultra-thin copper foil.
Solution Approach 2:
The patent converts the potential harm of thermal treatment (which normally deteriorates adhesion) into a benefit by using heat-resistant resin components that actually improve adhesion stability after reflow. The thermal history of the process enhances the crosslinking density and bonding performance of the composite resin system.
3Volume of moving object
If copper foil thickness is reduced to achieve miniaturization, then device size is reduced, but reliability deteriorates
Solution Approach 1:
The patent changes the resin composition parameters to create a chemically active bonding interface that compensates for the reduced copper foil thickness. The specific resin system with controlled molecular weight and functional group content enhances interfacial adhesion, ensuring reliability even with ultra-thin copper foils of 6 μm or less.
Solution Approach 2:
The patent uses a composite resin system that provides enhanced interfacial bonding through multiple interaction mechanisms (covalent bonding, hydrogen bonding, and physical entanglement). This composite material approach ensures that ultra-thin copper foils maintain sufficient mechanical and electrical reliability despite their reduced thickness.
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 solution enhances the peel strength between the ultra-thin copper foils and insulation materials, ensuring high reliability and stability of printed circuit boards with improved dimensional stability and thermal performance, suitable for high-speed and high-frequency signal transmission applications.
Implementation Method 1
the insulation material is made from a resin composition comprising oxazolidone epoxy resin, oxydianiline type benzoxazine (ODA-Bz) resin and a curing agent
Implementation Method 2
a glass transition temperature as measured by reference to IPC-TM-650 2.4.24.4 of greater than or equal to 185° C., such as between 190° C. and 220° C.; a dimensional change after reflow as measured by reference to IPC-TM-650 2.4.39 of less than or equal to 0.025%
Data Source
AI summary
Disclosed is an assembly comprising an insulation material and a copper foil disposed on the insulation material, wherein the copper foil has a thickness of less than or equal to 6 μm, and the insulation material is made from a resin composition comprising oxazolidone epoxy resin, oxydianiline type benzoxazine resin and a curing agent. The assembly achieves desirable balanced properties in peel strength, glass transition temperature, dimensional change after reflow, thermal resistance, and dielectric properties.