Oriented Graphite Heat Conduction Sheets for Uneven Surfaces
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Solution Overview
Problem
Existing heat conduction sheets face challenges in reducing thermal resistance due to the high heat generation and large size of semiconductor components, particularly with pressure bonding issues and uneven surfaces, necessitating improved thermal conductivity and flexibility.
Innovation Solution
A heat conduction sheet comprising a heat conduction layer with oriented graphite particles and an adhesive layer containing a resin component and heat conductive filler, which fills gaps between uneven surfaces for enhanced contact and reduces thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the heat conduction sheet is made thicker to accommodate chip level difference, then the flexibility and gap-filling capability improve, but the thermal resistance increases
Solution Approach 1:
The heat conduction sheet combines graphite particles (with high in-plane thermal conductivity) and metal particles (with high through-thickness thermal conductivity) in a resin matrix, creating a composite material that achieves both flexibility for gap-filling and low thermal resistance through the synergistic effect of different filler materials with complementary thermal conduction characteristics
Solution Approach 2:
The patent uses different types of particles with different properties: graphite particles primarily for in-plane heat conduction and metal particles for through-thickness heat conduction. This local differentiation of heat conduction pathways allows the material to maintain low thermal resistance even when thicker, while still providing the flexibility needed to accommodate chip level differences
2Reliability
If inorganic particles are oriented perpendicular to the sheet surface to improve thermal conductivity, then the through-thickness thermal conduction improves, but the manufacturing complexity and alignment precision requirements increase
Solution Approach 1:
Instead of requiring precise perpendicular orientation of all particles, the patent changes the approach by using metal particles with inherently high through-thickness thermal conductivity combined with graphite particles for in-plane conduction. This parameter change in the filler material selection reduces the need for complex orientation control during manufacturing while still achieving high thermal conductivity in both directions
Solution Approach 2:
The composite structure combines particles with different thermal conduction anisotropy characteristics: graphite particles provide excellent in-plane thermal conductivity, while metal particles provide excellent through-thickness thermal conductivity. This composite approach achieves high thermal conductivity in both directions without requiring complex orientation control, simplifying the manufacturing process
3Reliability
If pressure bonding force is reduced to prevent damage to semiconductor components, then the component integrity improves, but the contact between the heat conduction sheet and uneven surfaces worsens
Solution Approach 1:
The patent changes the material parameters of the heat conduction sheet by incorporating flexible resin components and using a bimodal particle distribution (graphite and metal particles of different sizes and shapes). This allows the material to deform and conform to uneven surfaces at low pressure, achieving good contact quality without compromising component integrity through excessive bonding force
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 sheet achieves low thermal resistance by orienting graphite particles in the thickness direction and using an adhesive layer to fill gaps, improving thermal conductivity and adhesion, thereby enhancing heat dissipation.
Implementation Method 1
a heat conduction layer containing at least one kind of graphite particles (A)
Implementation Method 2
an adhesive layer containing a resin component and a heat conductive filler, which is located on at least a part of a main surface of the heat conduction layer
Data Source
AI summary
A heat conduction sheet includes a heat conduction layer containing at least one kind of graphite particle (A) selected from the group consisting of scale-like particles, ellipsoidal particles and rod-like particles, in which in a case of scale-like particles, a plane direction of the particle is oriented in a thickness direction of the heat conduction sheet, and in a case of ellipsoidal particles or rod-like particles, a long axis direction of the particle is oriented in the thickness direction of the heat conduction sheet, and an adhesive layer containing a resin component and a heat conductive filler, which is located on at least a part of a main surface of the heat conduction layer.