Graphite Membrane Surface Smoothness via Tension Baking
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Solution Overview
Problem
Conventional methods fail to produce a graphite membrane with high surface smoothness, thin thickness, large area, and high electrical conductivity in the a-b plane direction, often resulting in wrinkles and undulations that hinder applications in miniaturized electronic devices and other precise uses.
Innovation Solution
Applying force to the polymer film during baking, specifically by pulling it outward along the film plane, to reduce wrinkles and enhance surface smoothness, while carbonizing and graphitizing the film to achieve a thickness of 10 nm to 12 µm and an electrical conductivity of 8000 S/cm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thin polymer film is used to produce a thin graphite membrane, then the thickness is reduced, but the mechanical strength becomes weaker and wrinkles increase
Solution Approach 1:
The patent applies force to the polymer film during the baking process, changing the mechanical parameters of the system. By applying tension force during thermal treatment, the film maintains mechanical strength despite its thinness, preventing wrinkles while achieving the desired thin graphite membrane structure with thickness of 10 nm to 12 µm
Solution Approach 2:
The force application is performed preliminarily during the baking process before the graphitization is complete. This preliminary mechanical action prevents wrinkle formation during the critical transformation phase, ensuring the final graphite membrane maintains both thinness and surface smoothness
2Manufacturing precision
If force is applied to reduce wrinkles during baking, then surface smoothness is improved, but the process complexity increases
Solution Approach 1:
The patent modifies the baking process by adding a force application parameter. The polymer film is subjected to controlled tension during thermal treatment, transforming the process from simple heating to a combined thermomechanical process that achieves superior surface smoothness with arithmetic average roughness of 200 nm or less
Solution Approach 2:
The applied force acts as an intermediary mechanism during baking, mediating between the thermal energy input and the structural outcome. This intermediate mechanical action controls wrinkle formation without requiring complex post-processing steps
3Length of stationary object
If the polymer film is made thinner to achieve thin graphite membrane, then the thickness is reduced, but the electrical conductivity may be affected
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: the force application during baking enhances the crystalline structure development, while the graphitization temperature and duration are controlled to ensure high electrical conductivity. The resulting graphite membrane achieves both thinness (10 nm to 12 µm) and high electrical conductivity (8000 S/cm or more in a-b plane direction)
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 a graphite membrane with exceptional surface smoothness and high electrical conductivity, suitable for applications in small-sized electroconductors, thermoconductors, and micro electromechanical systems (MEMS), with an arithmetic average roughness of 200 nm or less over a 5 mm or more square area.
Implementation Method 1
carbonizing and graphitizing the film
Implementation Method 2
carbonizing and graphitizing the film to achieve a thickness of 10 nm to 12 µm and an electrical conductivity of 8000 S/cm or more
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(b)
Figure 3
AI summary
The present invention contains a graphite membrane having a thickness of 10 nm to 12 µm, an area of 5 × 5 mm2 or more, an electrical conductivity of 8000 S/cm or more, and an arithmetic average roughness Ra of 200 nm or less on the surface of the graphite membrane. It is preferable that a kind of raw material polymer is polyimide, and the heating temperature at the graphitization of the raw material film is 2600 °C or more.