Metal-clad laminate adhesion via staged thermal drying
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Solution Overview
Problem
Metal-clad laminates with thermoplastic liquid crystal polymer films face challenges in achieving high frequency characteristics and sufficient adhesion strength while preventing blister generation, especially when using metal sheets with low roughness.
Innovation Solution
A method involving thermo-compression bonding of a metal sheet with a thermoplastic liquid crystal polymer film, followed by a drying process at a temperature lower than the melting point and for a duration of 10 seconds or longer, and subsequent heat-treatment above the melting point to enhance adhesion strength and prevent blistering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal sheet with low roughness is used to reduce insertion loss and improve high frequency characteristics, then adhesion strength between the metal sheet and thermoplastic liquid crystal polymer film becomes insufficient
Solution Approach 1:
The invention applies a preliminary drying process before heat treatment to remove volatile components from the thermoplastic liquid crystal polymer film. This preliminary action prevents blister formation during subsequent adhesion enhancement, allowing the use of low-roughness metal sheets for both high frequency performance and adequate adhesion strength
Solution Approach 2:
The invention changes the temperature parameter by implementing a two-stage thermal process: first drying at a temperature below the melting point to remove volatiles, then heat-treating at or above the melting point to enhance adhesion. This parameter progression enables achieving both good adhesion and high frequency characteristics with smooth metal sheets
2Strength
If the laminate is heat-treated at a temperature higher than the melting point of the thermoplastic liquid crystal polymer film to enhance adhesion strength, then blisters are generated due to expansion of volatilization components
Solution Approach 1:
The drying process is performed as a preliminary step before heat treatment. By removing volatile components at a lower temperature first, the invention prevents the formation of blisters that would otherwise occur during the subsequent high-temperature adhesion enhancement process
Solution Approach 2:
The thermal treatment process is segmented into two distinct stages: a drying stage at temperature below the melting point to remove volatiles, and a heat treatment stage at or above the melting point to enhance adhesion. This segmentation prevents the harmful effect of blister formation while achieving the desired adhesion strength
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 produces metal-clad laminates with improved adhesion strength and high frequency characteristics while inhibiting blister generation, even with metal sheets having low surface roughness, thus enhancing their performance and reliability.
Implementation Method 1
heat-treating the laminate at a temperature of equal to or higher than the melting point of the thermoplastic liquid crystal polymer film
Implementation Method 2
blisters were generated due to expansion of volatilization components, such as water included in the film
Data Source
Figure 1~4
AI summary
Provided is a method for producing a metal-clad laminate of a thermoplastic liquid crystal polymer film and a metal sheet(s) bonded to at least one surface of the film using roll-to-roll processing. The metal sheet has a surface with a ten-point average roughness (Rz) of 5.0 µm or less to be bonded to the thermoplastic liquid crystal polymer film. The method includes preparing the laminate, dry-treating the laminate by subjecting the laminate passed through a dry zone satisfying the following conditions (1) and (2): (1) the dry treatment is carried out at a drying temperature of lower than the melting point of the thermoplastic liquid crystal polymer film, (2) the dry treatment is carried out for a drying period of 10 seconds or longer, and heat-treating the dried laminate by subjecting the laminate passed through a heating zone on a temperature condition of not lower than the melting point of the thermoplastic liquid crystal polymer film successively after the dry treatment.