Power Conversion Circuit Body With Variable Thermal Interface Thickness
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Solution Overview
Problem
The existing power conversion devices experience peeling of the sheet member due to stress from the heat cycle of energization and de-energization of the power semiconductor element, leading to deterioration in insulating and heat dissipation properties.
Innovation Solution
The electric circuit body incorporates a heat conduction member with varying thickness across different projection regions, with increased thickness in the second projection region facing the sealing member, to mitigate stress concentration and prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sheet member is joined to a conductor plate in a power conversion device, then insulating and heat dissipation properties are achieved, but the sheet member peels off due to stress from heat cycles
Solution Approach 1:
The heat conduction member is designed with varying thickness: a first thickness in the first projection region and a second thickness (greater than the first) in the second projection region. This local quality variation allows the thicker portion to absorb thermal expansion stress while the thinner portion maintains adequate heat conduction, preventing sheet member peeling at the joint between the conductor plate and cooling member
Solution Approach 2:
The thickness parameter of the heat conduction member is changed across different regions to optimize both stress resistance and heat conduction. By increasing the thickness in the second projection region where stress concentration occurs, the structure can withstand thermal cycle stress without peeling, while the overall thin design maintains effective heat dissipation
2Reliability
If heat conduction member thickness is increased to prevent peeling, then peeling resistance improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of uniformly increasing the thickness of the entire heat conduction member, the design applies local quality by varying thickness only in specific regions. The first projection region maintains a thinner profile while the second projection region (at the joint area) has increased thickness, providing peeling resistance only where needed without adding unnecessary complexity elsewhere
Solution Approach 2:
The heat conduction member's thickness varies in the vertical dimension across different horizontal regions. This dimensional variation creates a gradient structure that naturally manages stress distribution and heat flow paths, achieving enhanced reliability through geometric design rather than adding separate components or complex assembly structures
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 design effectively suppresses peeling of the sheet member, maintaining insulating and heat dissipation properties by reducing shear stress concentration, thereby enhancing the reliability and performance of the electric circuit body.
Implementation Method 1
a heat conduction member provided between the opposite surface of the sheet member and the cooling member
Implementation Method 2
a cooling member that cools heat of the power semiconductor element
Data Source
AI summary
An electric circuit body including a power semiconductor element joined to one surface of a conductor plate; a sheet member including an insulating layer joined to the other surface of the conductor plate; a sealing member that integrally seals the sheet member, the conductor plate, and the power semiconductor element in a state where a surface of the sheet member opposite to a surface joined to the conductor plate is exposed; a cooling member that cools heat of the power semiconductor element; and a heat conduction member provided between the opposite surface of the sheet member and the cooling member, where the heat conduction member is provided over a first projection region facing the conductor plate and a second projection region facing the sealing member, and a thickness of the heat conduction member is thicker in the second projection region than in the first projection region.