Graphite Sheet Production via Phosphorus-Modified Polyimide Film
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Solution Overview
Problem
Existing graphite sheets face challenges in achieving high thermal diffusivity and interlaminar strength due to low productivity caused by film fusion during graphitization, as seen in conventional production methods.
Innovation Solution
A method involving a polyimide film with inorganic particles and a phosphorus-containing non-metal additive, where the inorganic particles and additive content are within specific ranges, is used for heat-treating the film to produce a graphite sheet with high thermal diffusivity and interlaminar strength, preventing film fusion during graphitization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a polyimide film containing inorganic particles is used for graphitization to achieve high thermal diffusivity, then thermal diffusivity is improved, but film fusion occurs during graphitization causing low productivity
Solution Approach 1:
A phosphorus-containing non-metal additive is introduced as an intermediary substance between the inorganic particles and the polyimide film matrix. This additive prevents direct fusion between inorganic particles and the film during graphitization while maintaining the thermal diffusivity benefits, thus resolving the contradiction between achieving high thermal diffusivity and preventing film fusion
Solution Approach 2:
The phosphorus content in the polyimide film is precisely controlled within the range of 0.018% to 0.032% by weight. This parameter optimization prevents film fusion during graphitization while preserving the thermal diffusivity enhancement from inorganic particles, thereby maintaining high productivity
2Temperature
If inorganic particles are added to polyimide film to enhance thermal diffusivity, then thermal diffusivity is improved, but interlaminar strength decreases due to film fusion
Solution Approach 1:
The phosphorus-containing non-metal additive acts as a mediator that prevents direct bonding between inorganic particles and the polyimide film during graphitization. This eliminates the film fusion that would otherwise reduce interlaminar strength while preserving the thermal diffusivity enhancement from the inorganic particles
Solution Approach 2:
A composite polyimide film is created containing inorganic particles (0.01% to 0.08% by weight) and phosphorus-containing non-metal additive (0.018% to 0.032% by weight). This composite structure combines the thermal diffusivity benefits of inorganic particles with the strength-preserving effect of the phosphorus additive, achieving both high thermal diffusivity and good interlaminar 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 enables the production of graphite sheets with enhanced thermal diffusivity and interlaminar strength while maintaining high productivity by preventing film fusion, making them suitable for heat dissipation in electronic devices.
Implementation Method 1
heat-treating a polyimide film to a temperature of not lower than 2800° C.
Implementation Method 2
preventing fusion of a film with itself or fusion between films during graphitization
Data Source
AI summary
An object is to provide, with high productivity, a graphite sheet having good thermal diffusivity and interlaminar strength. The object is attained by a method for producing a graphite sheet having a thermal diffusivity of not less than 10.0 cm2/s, the method including the step of heat-treating a polyimide film to a temperature of not lower than 2,800° C., the polyimide film containing: not less than 0.01% by weight and not more than 0.08% by weight of inorganic particles; and a non-metal additive containing not less than 0.018% by weight and not more than 0.032% by weight of phosphorus.