Ni-Zn Alloy Surface Treated Copper Foil for CCL Bonding
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Solution Overview
Problem
Current surface treatments for copper foils used in copper clad laminates (CCLs) fail to simultaneously achieve strong bonding with polyimide films, chemical resistance, and effective etching properties, particularly at high temperatures, leading to reliability issues in fine pitch circuits.
Innovation Solution
A surface treated copper foil with a Ni-Zn alloy layer, where the Zn content is between 6% and 15% and the Zn deposition amount is 0.08 mg/dm² or more, combined with a Cr treatment and silane coupling agent, to enhance bonding strength, heat resistance, and prevent chemical deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Zn plating is applied to improve bonding strength between copper foil and polyimide film, then bonding strength is improved, but chemical resistance deteriorates because Zn dissolves easily in acid during etching treatment
Solution Approach 1:
The patent applies a composite plating structure consisting of multiple layers: a base Zn plating layer for bonding strength, followed by a Ni plating layer for chemical resistance and etching performance, and optionally a Cr plating layer for additional protection. This composite structure allows each layer to fulfill its specific function without compromising the others, resolving the contradiction between bonding strength and chemical resistance.
Solution Approach 2:
The patent controls the thickness and composition ratios of each plating layer precisely. By optimizing the Zn layer thickness to provide sufficient bonding strength while limiting it to prevent excessive dissolution during etching, and by controlling Ni and Cr layer thicknesses for adequate protection, the patent achieves both strong bonding and chemical resistance through parameter optimization.
2Reliability
If multiple plating layers (Ni-Zn) are applied to achieve both bonding strength and chemical resistance, then both properties are improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple plating operations (Zn plating, Ni plating, Cr plating) into a unified surface treatment process that is applied to the copper foil before bonding with polyimide. By merging these treatments into a standard manufacturing sequence, the complexity is managed through process integration rather than separate complex operations.
3Reliability
If etching treatment time is shortened to prevent Zn layer dissolution, then chemical resistance is maintained, but productivity decreases due to advanced technology and management systems being required
Solution Approach 1:
The patent uses a thin Ni plating layer (0.01-0.05 mg/dm²) that serves as a sacrificial protective layer during etching. This thin layer is sufficient to prevent Zn dissolution and maintain chemical resistance, allowing standard etching times to be used without requiring extended treatment or complex management systems, thus maintaining productivity.
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 provides a copper foil that maintains high bonding strength, chemical resistance, and etching properties, even after heat treatment and acid exposure, ensuring reliable circuit formation and reduced peeling risks in fine pitch circuits.
Implementation Method 1
a surface treated copper foil comprising an untreated copper foil on at least one surface of which Ni-Zn alloy is deposited
Implementation Method 2
the copper foil and the polyimide are bonded by thermal adhesion at high temperature of several hundreds of degrees
Data Source
AI summary
To provide a surface treated copper foil satisfying all of the bonding strength to polyimide film, chemical resistance, and etching property, and to provide a CCL using the surface treated copper foil, a surface treated copper foil is formed being comprising an untreated copper foil on at least one surface of which Ni—Zn alloy is deposited, wherein Zn content (wt %)=Zn deposition amount/(Ni deposition amount+Zn deposition amount)×100 is 6% or more and 15% or less, and Zn deposition amount is 0.08 mg/dm2 or more, or, a CCL is formed being comprising a surface treated copper foil and a polyimide film laminated on the surface treated copper foil, wherein the surface treated copper foil comprises an untreated copper foil on at least one surface of which Ni—Zn alloy is deposited, Zn content (wt %)=Zn deposition amount/(Ni deposition amount+Zn deposition amount)×100 is 6% or more and 15% or less, and Zn deposition amount is 0.08 mg/dm2 or more.