Copper Foil Carrier Sheet Release Layer
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Solution Overview
Problem
Conventional electrodeposited copper foils with carrier foils lack stable release strength at high temperatures above 300°C, leading to defects in copper-clad laminates and making them unsuitable for industrial production of fine pitch circuits.
Innovation Solution
A copper foil with a carrier sheet featuring a bonding interface layer composed of a metal layer and a carbon layer formed by sputtering vapor deposition, providing a stable and low release strength for easy carrier sheet removal even after high-temperature hot pressing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional release layer is used between carrier foil and copper foil layer, then the structure is simple, but the release strength becomes unstable at high temperatures above 300°C
Solution Approach 1:
The release layer is constructed as a composite structure with a metal oxide layer (1-50 nm) and an organic agent layer (5-50 nm). This composite design combines the thermal stability of metal oxide with the release properties of organic agents, achieving stable release strength at high temperatures while maintaining reasonable structure complexity.
Solution Approach 2:
The patent optimizes the thickness parameters of both layers within specific ranges (metal oxide: 1-50 nm, organic agent: 5-50 nm) to achieve the desired balance between adhesion and release properties at high temperatures.
2Strength
If the release strength is increased to prevent carrier foil tearing, then the carrier foil remains attached too strongly, but if decreased for easy removal, then counter diffusion occurs at high temperatures
Solution Approach 1:
The metal oxide layer serves as an intermediary between the carrier foil and copper foil layer. It provides thermal stability and controlled adhesion while allowing the organic agent layer to provide the necessary release properties, preventing both excessive adhesion and counter diffusion at high temperatures.
Solution Approach 2:
The combination of metal oxide and organic agent creates a composite release layer that balances adhesion and release properties, enabling easy carrier foil removal while preventing counter diffusion during high-temperature hot pressing.
3Productivity
If thinner copper foils are used to achieve fine-pitch wirings, then the packaging density increases, but the handling becomes difficult and wrinkles form
Solution Approach 1:
The carrier foil acts as a flexible support film for the thin copper foil during handling and processing. The release layer ensures the carrier can be easily removed after use, enabling the use of ultra-thin copper foils for fine-pitch wirings while maintaining handling ease throughout the manufacturing process.
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 ensures stable and controlled release of the carrier sheet from the copper foil layer at temperatures exceeding 300°C, preventing defects and enabling the production of high-quality copper-clad laminates for fine pitch circuits.
Implementation Method 1
a bonding interface layer which is characterized in that the bonding interface layer has two layer structure composed of a metal layer and a carbon layer formed by using physical vapor deposition
Data Source
AI summary
An object of the present invention is to provide a copper foil with carrier sheet which permits releasing of the carrier sheet from the copper foil layer even when hot pressing at a temperature exceeding 300° C. is applied in the production of a printed wiring board. In order to achieve the object, a copper foil with physically releasable carrier sheet having a copper foil layer on the surface of the carrier sheet through a bonding interface layer, characterized in that the bonding interface layer is composed of a metal layer and a carbon layer. It is preferable for the bonding interface layer to be composed of a metal layer of 1 nm to 50 nm thick and a carbon layer of 1 nm to 20 nm thick.