Copper Clad Laminate With Low-Ni Plating for High-Frequency Flex Circuits
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Solution Overview
Problem
Existing methods for producing flexible circuit boards with copper clad laminates face challenges in achieving high adhesion between low dielectric resin films and electroless copper plating layers while maintaining low transmission loss and good volume resistivity, particularly at high frequencies.
Innovation Solution
A copper clad laminate is developed with a low dielectric resin film and an electroless copper plating layer containing 0.01 to 1.2 wt% Ni, having a volume resistivity of 6.0 μΩ·cm or lower, and an average surface roughness of 1 to 150 nm, with optional electrolytic copper plating, and a production method involving surface modification and heating steps to enhance adhesion and deposition properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an electroless copper plating layer is formed on a low dielectric resin film to achieve good adhesion, then adhesion strength is improved, but transmission loss increases due to high Ni content in the plating layer
Solution Approach 1:
The invention changes the concentration parameters of the electroless plating bath, specifically controlling the Ni content to 0.01-1.2 wt% and Cu content to 98.8-99.99 wt%, to achieve optimal adhesion while minimizing transmission loss. This precise parameter control resolves the contradiction by finding the optimal balance point between adhesion strength and transmission loss.
Solution Approach 2:
The invention creates a plating layer with non-uniform composition by controlling the deposition process to achieve specific Ni distribution that promotes adhesion at the interface while keeping overall Ni content low to minimize transmission loss. The local quality of the plating layer varies to satisfy both adhesion and low loss requirements.
2Reliability
If Ni content in the electroless copper plating layer is increased to improve deposition properties, then adhesion is improved, but volume resistivity increases and magnetism is introduced
Solution Approach 1:
The invention optimizes the Ni content parameter to a specific range (0.01-1.2 wt%) that provides sufficient deposition properties and adhesion while preventing excessive volume resistivity and magnetism. This parameter optimization resolves the contradiction by identifying the optimal concentration window.
3Reliability
If sputtering process is used to form copper layer on low dielectric film, then conductive film is formed, but production complexity increases and productivity decreases
Solution Approach 1:
The invention replaces the sputtering process (physical vapor deposition) with an electroless plating process (chemical deposition). This substitution maintains the ability to form high-quality copper conductive films while dramatically improving production efficiency and reducing process complexity, as electroless plating is a simpler, more scalable process.
4Strength
If electroless copper plating is applied to low dielectric resin film to achieve good adhesion, then adhesion is improved, but transmission loss increases due to surface roughness
Solution Approach 1:
The invention optimizes the surface roughness parameter of the electroless copper plating layer to a specific range that provides sufficient adhesion while minimizing transmission loss. By controlling the plating bath composition and deposition conditions, the surface roughness is maintained at an optimal level that balances adhesion and transmission characteristics.
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 achieves high adhesion and low transmission loss, enabling the production of flexible circuit boards with improved conductivity and reduced impedance variations, suitable for high-frequency applications.
Implementation Method 1
an electroless copper plating layer formed on at least one surface of the low dielectric resin film
Implementation Method 2
a dielectric loss that occurs in such a circuit board is known to be proportional to the product of three elements consisting of 'the frequency of a signal,' 'a square root of a dielectric constant of a board material' and 'a dissipation factor'
Data Source
AI summary
A copper clad laminate is provided that is capable of achieving a good volume resistivity at an electroless copper plating layer of a low dielectric resin film while suppressing a transmission loss when being applied to a flexible circuit board, and a method for producing the copper clad laminate. The copper clad laminate of the present invention includes a low dielectric resin film having a relative permittivity of 3.5 or lower and a dissipation factor of 0.008 or lower at a frequency of 10 GHZ, and an electroless copper plating layer laminated on at least one surface of the low dielectric resin film. An Ni content in the electroless copper plating layer is 0.01 to 1.2 wt %, and the electroless copper plating layer has a volume resistivity of 6.0 μΩ·cm or lower.