Polyimide Film High Molecular Weight Graphite Thermal Conductivity
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Solution Overview
Problem
Current methods for preparing graphite sheets do not effectively enhance thermal conductivity, which is crucial for efficient heat dissipation in increasingly compact electronic devices.
Innovation Solution
A polyimide film is prepared by reacting a diamine monomer with an acid dianhydride monomer in a solvent, followed by mixing with an imidization solution and heat treatment, controlling the solid content and viscosity to achieve a weight-average molecular weight of 240,000 or more, and incorporating inorganic particles as fillers to improve windability and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional methods are used to prepare graphite sheets by carbonization and graphitization of polyimide resin, then graphite sheets can be obtained, but the thermal conductivity is insufficient for effective heat dissipation
Solution Approach 1:
The patent changes the molecular weight parameter of the polyimide resin to 240,000 or more, which is significantly higher than conventional resins. This parameter change leads to longer carbon chains after carbonization, creating more efficient thermal conduction pathways in the graphite sheet, thereby resolving the contradiction between obtaining graphite sheets and achieving sufficient thermal conductivity
Solution Approach 2:
The patent uses polyimide resin as a precursor material that transforms into graphite through carbonization. This composite approach, where the resin structure is designed to convert into a graphite structure with enhanced properties, allows achieving superior thermal conductivity (400-500 W/m·K) compared to conventional graphite preparation methods
2Temperature
If the solid content and viscosity of polyamic acid solution are increased to achieve higher molecular weight polyimide, then thermal conductivity improves, but the solution becomes harder to process
Solution Approach 1:
The patent optimizes two critical parameters of the polyamic acid solution: solid content (15-20%) and viscosity (55,000-900,000 cps at 23°C). These parameter ranges balance the need for high molecular weight (for thermal conductivity) with processability requirements, allowing the solution to be handled and processed effectively while still achieving the desired molecular weight after imidization
Solution Approach 2:
The patent specifies a viscosity range that is higher than conventional solutions would suggest, but not excessively high. This partial excessive action in viscosity (up to 900,000 cps) allows achieving the necessary molecular weight while still maintaining enough fluidity for processing, resolving the contradiction between high molecular weight and ease of manufacture
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 resulting graphite sheets exhibit enhanced thermal conductivity and improved windability, effectively addressing the thermal management challenges in electronic devices.
Implementation Method 1
preparing a polyamic acid solution by reaction of a diamine monomer with an acid dianhydride monomer in a solvent
Implementation Method 2
imidizing the gel film by performing a heat treatment
Implementation Method 3
a polyimide (PI) resin is prepared by imidization of the polyamic acid derivative via ring-closing dehydration at a high temperature
Implementation Method 4
a graphite sheet has been prepared by carbonization and graphitization of a polyimide resin
Implementation Method 5
a graphite sheet has been prepared by carbonization and graphitization of a polyimide resin
Data Source
AI summary
The present invention relates to a polyimide film and a preparation method thereof. According to the present invention, a polyamic acid solution having a high weight-average molecular weight may be obtained by adjusting viscosity and solid content of the polyamic acid solution, and thus, a desired polyimide film may be prepared therefrom. Furthermore, since a length of carbon chains rearranged during graphitization is increased, a graphite sheet having excellent thermal conductivity can be prepared from the polyimide film of the present invention. Also, since the polyimide film has improved windability by further including inorganic particles as a filler, it may facilitate the wind operation.