Multilayer Polyimide Film Composition for Low-Loss Lamination
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Solution Overview
Problem
Existing polyimide films face challenges with high dielectric dissipation factors and inadequate adhesive strength, particularly at high frequencies, leading to instability and poor insulation properties in flexible copper-clad laminates for high-speed communication.
Innovation Solution
A multilayer polyimide film structure is developed, comprising a core layer and skin layers with specific compositions and thicknesses, using biphenyl-tetracarboxylic and pyromellitic dianhydrides and diamines, to achieve a dielectric dissipation factor of 0.003 or less and adhesive strength of 1,000 gf/cm or more, suitable for high-speed transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thermoplastic resin is used for adhesion between the polyimide film and the metal foil in laminating, then adhesive strength can be achieved, but high temperature (300°C or higher) is required which causes significant decrease in storage modulus and dimensional instability of the polyimide film
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyimide film by incorporating specific aromatic diamine components and controlling the ratio of aromatic to aliphatic diamine units. This compositional parameter change enables the film to achieve both high adhesive strength (≥1000 gf/cm) and dimensional stability during high-temperature lamination, resolving the contradiction between adhesion and stability
Solution Approach 2:
The patent creates a composite polyimide structure by combining different diamine components (aromatic and aliphatic) with specific ratios. This composite material approach allows the film to exhibit both strong adhesion properties and dimensional stability simultaneously, overcoming the limitation of single-component polyimide films
2Temperature
If the glass transition temperature of the polyimide film is significantly lower than the laminating temperature, then the viscosity of the polyimide film becomes relatively high at the laminating temperature, causing significant dimensional change and deterioration in appearance quality
Solution Approach 1:
The patent adjusts the glass transition temperature parameter by modifying the diamine component composition. By controlling the ratio of aromatic to aliphatic diamine units within specific ranges, the Tg is optimized to be sufficiently high relative to the lamination temperature, preventing excessive viscosity and dimensional changes that would compromise appearance quality
3Reliability
If typical polyimide is used, then good insulation properties are achieved, but the dielectric constant is relatively high (3.4 to 3.6) which is not sufficient for high-frequency communication above 10 GHz
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide by selecting specific diamine components with appropriate aromatic and aliphatic ratios. This structural parameter modification reduces the dielectric constant to 3.6 or lower while preserving excellent insulation properties, enabling high-frequency communication performance above 10 GHz
Data Source
AI summary
The present invention provides a multilayer polyimide film and a method for manufacturing same, the multilayer polyimide film comprising at least one skin layer, which is formed on at least one outer surface of a core layer, and having a dielectric dissipation factor of 0.003 or less and an adhesive force of 1,000 gf/cm or more.