Surface-Treated Copper Foil for Fine Line Adhesion
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Solution Overview
Problem
The adhesion strength between conductive lines and the board in copper-clad laminates is reduced due to the flatness of the copper foil surface, leading to peeling issues and discrepancies in pattern transfer during etching, especially with the miniaturization of line width and line space.
Innovation Solution
A surface-treated copper foil with a bulk copper foil and a first surface treatment layer featuring a roughening layer, with a material volume of 0.06 to 1.45 μm3/μm2 and a five-point peak height of 0.15 to 2.00 μm, enhancing adhesion and etch factor for improved pattern transfer and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface of the copper foil is flattened to enable fine line width/line space fabrication, then the manufacturing precision of conductive lines is improved, but the adhesion strength between conductive lines and the board is reduced
Solution Approach 1:
The invention applies different surface qualities to different regions of the copper foil. The surface facing the board maintains relative flatness for good adhesion, while the surface facing the photoresist is flattened only in specific areas to enable fine line fabrication. This local differentiation resolves the contradiction between adhesion strength and manufacturing precision.
Solution Approach 2:
The copper foil surface is pre-treated with specific flattening processes before the etching stage. This preliminary action ensures that the surface is ready for fine line fabrication while maintaining the necessary adhesion properties, preventing the need for rework or adjustment during subsequent manufacturing steps.
2Manufacturing precision
If the surface of the copper foil is flattened to enable fine line fabrication, then the manufacturing precision is improved, but the pattern transfer fidelity differs from the photoresist pattern
Solution Approach 1:
The invention creates local quality variations on the copper foil surface, with specific regions flattened to match the photoresist pattern geometry. This ensures that the etched conductive lines accurately reproduce the intended pattern while maintaining overall surface quality for adhesion.
Solution Approach 2:
The invention replaces mechanical flattening processes with more precise surface treatment methods that can control the surface geometry at the micro-scale. This substitution enables better pattern transfer fidelity by accurately replicating the photoresist pattern on the copper foil surface before etching.
3Productivity
If the line width and line space are miniaturized to meet small-sized electronic product requirements, then the productivity and miniaturization are improved, but the adhesion strength and pattern accuracy are reduced
Solution Approach 1:
The invention applies local quality control to the copper foil surface, creating micro-scale variations that enhance adhesion in critical areas while maintaining the flatness needed for fine line fabrication. This allows miniaturization of conductive lines without sacrificing overall adhesion strength or pattern accuracy.
Data Source
AI summary
A surface-treated copper foil includes a bulk copper foil and a first surface treatment layer. The first surface treatment layer is disposed on a first surface of the bulk copper foil and includes a roughening layer, where the outermost surface of the first surface treatment layer is a treating surface of the surface-treated copper foil. The material volume (Vm) of the treating surface is 0.06 to 1.45 μm3/μm2, and the five-point peak height (S5p) of the treating surface is 0.15 to 2.00 μm.