Graphite Composite Film With Through Holes For Metal Adhesion
Solution Overview
Problem
Graphite films exhibit poor adhesion to metals and resins, leading to peeling issues during heat treatment and handling due to low surface activity, and challenges in joining with metal plates using solder.
Innovation Solution
A graphite composite film is created with a metal layer formed on the surface and inside through holes of the graphite film, where the through holes have a specific diameter and spacing, and the metal layer is connected from one side to the other, ensuring a metal area ratio of 1.4% or more within the composite film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal layer is directly formed on the surface of a graphite film, then the adhesion between metal and graphite is improved, but the metal layer is easily peeled off during heat treatment or handling due to poor adhesion
Solution Approach 1:
The invention divides the metal layer into two functional parts: a first metal layer formed on the graphite film surface providing adhesion, and a second metal layer formed on the first metal layer providing heat resistance. This segmentation allows each layer to specialize in one function, preventing the single-layer structure from having to compromise between adhesion and heat resistance requirements
Solution Approach 2:
The invention creates a composite metal layer structure where two different metal layers are combined. The first metal layer (e.g., nickel) provides strong adhesion to graphite, while the second metal layer (e.g., copper or aluminum) provides excellent heat dissipation and solderability. This composite structure resolves the contradiction by combining materials with complementary properties
2Strength
If the metal layer thickness is increased to improve adhesion, then adhesion strength is improved, but heat dissipation performance deteriorates
Solution Approach 1:
The invention applies different metal layers with different properties to different locations/functions: the first metal layer (thinner, 1-10 μm) is applied where adhesion is needed (directly on graphite), while the second metal layer (thicker, 10-50 μm) is applied where heat dissipation is prioritized (on top of the first layer). This local differentiation optimizes both adhesion and heat dissipation without compromise
Solution Approach 2:
By combining a thin adhesion-promoting metal layer with a thicker heat-dissipating metal layer, the composite structure achieves both strong adhesion and excellent heat dissipation. The thin first layer minimizes thermal resistance while the thick second layer maximizes heat dissipation capacity
3Temperature
If a graphite film is used as a heat dissipator with a resin layer formed on its surface, then heat dissipation performance is achieved, but void formation or separation occurs between the graphite film and resin layer during molding
Solution Approach 1:
The first metal layer acts as an intermediary between the graphite film and the resin layer. It provides a surface with properties that are compatible with both graphite and resin, enabling reliable adhesion of the resin layer while maintaining the heat dissipation function of the graphite film. This intermediary layer prevents void formation and separation during molding
4Ease of manufacture
If a graphite film is brazed with solder to join with metal plates, then joining is attempted, but the graphite film is poor in affinity for solder making joining difficult
Solution Approach 1:
The second metal layer (copper or aluminum) serves as an intermediary that provides excellent solder affinity. Instead of attempting to solder directly to graphite which has poor solder wetting properties, the solder is applied to the second metal layer which readily accepts solder, enabling reliable joining to metal plates while the graphite film maintains its heat dissipation function
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
This configuration enhances the adhesion and prevents peeling of the metal layer from the graphite film, improving soldering heat resistance and interlaminar strength, while maintaining high heat dissipation performance.
Implementation Method 1
the metal layer on the surface of the graphite film is formed by plating
Implementation Method 2
A graphite film offers high heat dissipation performance due to its high heat conductivity
Data Source
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AI summary
There is provided a graphite composite film including a graphite film and a metal layer formed on a surface of the graphite film, in which peeling-off of the metal layer from the graphite film is suppressed. More specifically, the graphite composite film includes a graphite film and a metal layer formed on at least one side of the graphite film, wherein the graphite film has a plurality of through holes formed therein, a metal layer is formed also inside the through holes so as to be connected to the metal layer formed on a surface of the graphite film, the metal layer inside the through holes is formed continuously from the one side to an opposite side of the graphite film, and a distance between outer diameters of the through holes is 0.6 mm or less and a ratio of an area of metal inside the through holes to an area of the graphite composite film is 1.4% or more.