Thin Polyimide Copper Clad Laminate Flexibility
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Solution Overview
Problem
Conventional copper-clad laminates with polyimide films of 25 μm thickness lack flexibility and adhesiveness, leading to issues like wrinkle formation and poor surface slipping properties, which restrict their use in applications requiring high mechanical properties and fine patterns.
Innovation Solution
A copper-clad laminate is developed with a polyimide film thickness of 5 to 20 μm and a copper foil thickness of 1 to 18 μm, using a thermocompression-bonding process with a thermoplastic polyimide layer containing dispersed polyimide particles, enhancing flexibility and surface slipping properties without inorganic powders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyimide film with a thickness of about 25 μm is used, then the film has good mechanical strength and heat resistance, but the laminate lacks flexibility and cannot be adequately bent
Solution Approach 1:
The patent changes the thickness parameter of the polyimide film from the conventional 25 μm to a thinner range of 10 to 20 μm. This parameter change reduces the overall laminate thickness, thereby improving flexibility and bendability while maintaining sufficient mechanical strength through optimized material composition and structure.
2Reliability
If surface processing such as alkaline treatment, corona treatment, or sandblasting is performed to improve adhesiveness, then adhesive properties are enhanced, but heat resistance deteriorates due to the use of additional adhesive materials
Solution Approach 1:
The patent extracts and eliminates the need for separate adhesive materials by incorporating adhesive functional groups directly into the polyimide film structure itself. This integration allows the polyimide to provide both mechanical strength and adhesive properties without requiring additional adhesive layers that would compromise heat resistance.
Solution Approach 2:
The patent uses composite materials by combining polyimide with specific additives or copolymers that enhance adhesive properties while maintaining the inherent heat resistance of polyimide. This composite approach allows simultaneous achievement of good adhesion and high-temperature stability without relying on external adhesive materials.
3Shape
If a smooth surface is provided on the polyimide film to improve appearance, then the film has good visual quality, but friction against rolls increases causing wrinkle formation and twisting during winding
Solution Approach 1:
The patent applies local quality by providing a controlled surface treatment only on the outer surface of the polyimide film while maintaining the bulk material's smoothness and integrity. This localized modification reduces surface friction to prevent wrinkle formation during winding, while the overall film structure remains smooth and aesthetically pleasing.
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 laminate achieves significantly improved flexibility, with MIT folding endurance increased to over 2000 times, and prevents defects like wrinkles during lamination, ensuring a smooth, defect-free appearance and improved processability.
Implementation Method 1
a copper foil is laminated onto a polyimide film by thermocompression bonding
Data Source
AI summary
A copper-clad laminate is prepared by laminating a copper foil on one side or both sides of a polyimide film by thermocompression bonding. The flexibility of the copper-clad laminate is remarkably improved by employing a polyimide film having a thickness of 5 to 20 μm and a copper foil having a thickness of 1 to 18 μm.