Surface Treated Copper Foil Roughness Control for Wiring Boards
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Solution Overview
Problem
The existing methods for manufacturing printed wiring boards face issues with contamination from roughening particles on the copper foil, leading to potential short circuits and wrinkles or stripes when bonding with insulating substrates, which are not adequately addressed in terms of particle dropping and bonding quality.
Innovation Solution
The surface treated copper foil is engineered with specific roughness values (Ra, Rz, Sq, Ssk, Sa, Sz, Sku, Spk) and glossiness (70% or less) to control particle dropping and ensure smooth bonding with insulating substrates, incorporating a roughening treatment layer that maintains adhesion while preventing particle detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the roughening treatment layer is applied to improve adhesion to insulating resin, then adhesion is improved, but roughening particles drop off during contamination removal causing conductive contamination
Solution Approach 1:
The invention changes the physical parameters of the roughening treatment layer by controlling the average particle diameter within 0.5-5 μm and the volume ratio of particles with diameter of 0.5-2 μm to be 20-80%. These parameter optimizations ensure sufficient adhesion strength while preventing particle dropping during contamination removal, thus resolving the contradiction between adhesion improvement and contamination prevention.
2Length of moving object
If fine pitch conductor patterns are implemented for miniaturization, then miniaturization is achieved, but contamination removal causes particle dropping and short circuits
Solution Approach 1:
The invention optimizes the particle size parameters of the roughening treatment layer (average diameter 0.5-5 μm, with 0.5-2 μm particles comprising 20-80% of volume) to create a surface structure that maintains adhesion during contamination removal. This allows fine pitch conductor patterns to be implemented without causing particle dropping that would lead to short circuits, thus resolving the contradiction between miniaturization and reliability.
3Strength
If surface treatment is applied to improve adhesion, then adhesion is improved, but wrinkles or stripes occur during bonding with insulating substrate
Solution Approach 1:
The invention optimizes the particle size distribution parameters (average diameter 0.5-5 μm, with 0.5-2 μm particles making up 20-80% of volume) to create a roughening treatment layer that provides sufficient adhesion while maintaining a surface morphology free of wrinkles and stripes during bonding. This resolves the contradiction between adhesion improvement and bonding surface quality.
Data Source
AI summary
The present invention provides a surface treated copper foil in which a dropping of the roughening particles from a roughening treatment layer on the surface of the copper foil is suppressed and an occurrence of wrinkles or stripes when bonding with an insulating substrate is suppressed. The surface of the roughening treatment layer satisfies one or more of the following: a roughness Ra is 0.08 to 0.20 μm, a roughness Rz is 1.00 to 2.00 μm, a roughness Sq is 0.16 to 0.30 μm, a roughness Ssk is −0.6 to −0.35, a roughness Sa is 0.12 to 0.23 μm, a roughness Sz is 2.20 to 3.50 μm, a roughness Sku is 3.75 to 4.50, and a roughness Spk is 0.13 to 0.27 μm, a glossiness of a TD of the surface of the side of the roughening treatment layer of the surface treated copper foil is 70% or less.