Metal-Clad Laminate Roughness Control for Strong Foil Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods struggle to increase the thickness of the insulating layer in metal-clad laminates without causing a decline in the peel strength of the metal foil, which affects the stability and performance of printed wiring boards.
Innovation Solution
A manufacturing method involving the continuous feeding of metal foils and insulating films between endless belts, followed by hot-press molding, where the insulating films have surfaces with controlled roughness differences to enhance adhesion and thickness, resulting in an insulating layer with a thickness of 100-300 μm and peel strength of 0.60 N/mm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of the insulating layer is increased to reduce transmission losses, then the RF characteristics are improved, but the peel strength of the metal foil with respect to the insulating layer deteriorates
Solution Approach 1:
The patent applies local quality by creating asymmetric surface roughness on the insulating films - one surface has higher roughness (Rz≥1.5μm) to enhance metal foil adhesion, while the other surface has lower roughness (Rz≤3.0μm) to ensure proper bonding with adjacent insulating layers. This localized differentiation of surface properties allows the thick insulating layer (100-300μm) to maintain both low transmission loss and high peel strength (≥0.60N/mm)
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the ten-point mean roughness (Rz) values of the insulating film surfaces within specific ranges. By adjusting the surface roughness parameters of different faces of the insulating films and ensuring the absolute difference between contacting surfaces is ≤0.35μm, the patent achieves optimal balance between transmission loss reduction (through increased thickness) and peel strength maintenance
2Loss of energy
If multiple insulating films are stacked to increase insulating layer thickness, then transmission loss is reduced, but the manufacturing complexity and control of surface roughness uniformity increase
Solution Approach 1:
The patent applies segmentation by dividing the thick insulating layer into multiple individual insulating films (each with thickness L/2 to 5L/6 where L is total thickness). These segmented films are stacked and hot-press molded together, with each film having controlled surface roughness on both faces. This segmentation approach enables achieving the desired total thickness (100-300μm) for low transmission loss while managing manufacturing complexity through standardized film units
Solution Approach 2:
The patent manages manufacturing complexity through parameter changes by establishing specific roughness control criteria: each insulating film's first surface has Rz≥1.5μm, the second surface has Rz≤3.0μm, and the absolute difference between surfaces of adjacent films is ≤0.35μm. These quantified parameters provide clear manufacturing guidance, transforming the complex multi-film stacking process into a controllable procedure that ensures both performance and consistency
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 method allows for increased thickness of the insulating layer, reducing transmission losses and maintaining high peel strength, thereby enhancing the stability and performance of printed wiring boards.
Implementation Method 1
hot-press molding the first sheet of metal foil, the plurality of insulating films, and the second sheet of metal foil together to form an insulating layer out of the plurality of insulating films
Implementation Method 2
The resin layers each contain a liquid crystal polymer. A peel strength of the sheet of metal foil with respect to the insulating layer is equal to or greater than 0.60 N/mm
Data Source
AI summary
A manufacturing method includes stacking, between two endless belts, a first sheet of metal foil, a plurality of insulating films, and a second sheet of metal foil in this order one on top of another and hot-press molding these sheets and films together to form an insulating layer out of the plurality of insulating films. Each of the plurality of insulating films has a first surface and a second surface. The second surface has a larger ten-point mean roughness (Rzjis) than the first surface. The absolute value of difference between a ten-point mean roughness (Rzjis) of a surface, in contact with the first sheet of metal foil, of the insulating layer and a ten-point mean roughness (Rzjis) of another surface, in contact with the second sheet of metal foil, of the insulating layer is equal to or less than 0.35 μm.