Copper-Clad Laminate Zinc Layer Adhesion Fluororesin
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Solution Overview
Problem
High-frequency printed wiring boards using fluororesins face challenges with adhesion between copper foils and resin substrates, particularly at high temperatures, leading to reduced reliability and increased transmission loss.
Innovation Solution
A copper-clad laminate is developed with a surface-treated copper foil featuring a zinc-containing layer composed of Zn and a transition element with a melting point of 1200°C or more, where the emission intensity ratios IZn/ICu and IZn/IM are within specific ranges, enhancing adhesion and heat resistance without increasing transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a low dielectric constant thermoplastic resin (fluororesin) is used to reduce dielectric loss, then transmission loss is reduced, but adhesion force to copper foil deteriorates
Solution Approach 1:
The patent introduces a zinc-containing layer as an intermediary between the copper foil and fluororesin substrate. This intermediate layer has specific compositional characteristics (Zn content 1-10 wt%, transition element M content 90-99 wt%) that enable it to bond effectively with both the copper foil and the fluororesin, resolving the adhesion problem while maintaining the low dielectric constant properties of the fluororesin
2Strength
If conventional surface treatment (oxidation and reduction) is applied to copper foil to improve adhesion, then adhesion force is improved, but heat-resistant adhesion deteriorates
Solution Approach 1:
The patent changes the compositional parameters of the surface treatment layer by introducing a specific zinc-containing layer with controlled Zn and transition element M content ratios. This compositional parameter change creates a layer that maintains stable adhesion properties across a wide temperature range, unlike conventional oxidation-reduction treatments that degrade at high temperatures
3Strength
If roughness of copper foil surface is increased to ensure adhesion strength, then adhesion force is improved, but transmission loss increases
Solution Approach 1:
The patent applies local quality modification by creating a zinc-containing layer with specific compositional characteristics at the interface between copper foil and fluororesin. This localized compositional change provides enhanced adhesion at the bonding interface without affecting the overall smoothness and electrical properties of the copper foil surface, thus avoiding increased transmission loss
Data Source
AI summary
Provided is a copper-clad laminate in which a copper foil and a resin are joined together with high heat-resistant adhesion force though a fluororesin is used. This copper-clad laminate includes a surface-treated copper foil including a copper foil and a zinc-containing layer on at least one surface of the copper foil; and a sheet-shaped fluororesin on the zinc-containing layer side of the surface-treated copper foil. The zinc-containing layer is composed of Zn and a transition element M having a melting point of 1200° C. or more. When the interface between the copper foil and the zinc-containing layer is subjected to elemental analysis by GD-OES, the emission intensity ratio IZn/ICu of the emission intensity of Zn to that of Cu is 3.0×10−3 or less, and the emission intensity ratio IZn/IM of the emission intensity of Zn to that of the transition element M is 0.30 to 0.50.