Semiconductor Device Thermal Management via Local Quality Placement
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Solution Overview
Problem
The existing semiconductor devices face reliability issues due to heat cycle-induced cracks in the solder joining material, which degrade the heat radiation properties and reduce the stability of silicon switching elements compared to silicon carbide diode elements, leading to inefficient cooling and potential device failure.
Innovation Solution
The semiconductor device design includes wide-band-gap semiconductor elements positioned at the outer peripheral edge portions of the circuit board, while silicon semiconductor elements are placed at the central area, avoiding the cracked regions and maintaining efficient heat radiation by utilizing a laminated substrate with a metal cooling plate and conductive joining materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicon switching elements are disposed over corner portions of the circuit board to improve cooling efficiency, then heat radiation is improved, but cracks appear in the solder under the laminated substrate due to heat cycles, degrading reliability
Solution Approach 1:
The patent applies local quality by differentiating the placement strategy for different types of semiconductor elements based on their thermal characteristics. SiC diode elements (high temperature tolerance) are placed in the central area where heat accumulation occurs, while Si switching elements (lower temperature tolerance) are placed around the central area where cooling is more effective. This spatial differentiation of element placement according to local thermal conditions resolves the contradiction between heat radiation efficiency and solder crack resistance.
2Reliability
If silicon carbide diode elements are disposed in the central area to utilize their high temperature stability, then device performance is improved, but heat radiation becomes difficult in this region, causing temperature rise
Solution Approach 1:
The patent utilizes local quality by matching semiconductor element characteristics with local thermal conditions in the circuit board. The central area, which has poor heat radiation capability, is assigned SiC diode elements that can operate stably at high temperatures. Conversely, areas with better cooling are assigned Si switching elements that require lower operating temperatures. This spatial assignment resolves the contradiction between high temperature stability and heat radiation difficulty.
3Ease of manufacture
If solder joining material is used to join the metal board and cooling plate, then assembly is simplified, but cracks develop in the solder due to thermal expansion differences during heat cycles, degrading heat radiation
Solution Approach 1:
The patent addresses the solder crack issue by strategically placing semiconductor elements according to their thermal tolerance in relation to the solder joints. SiC elements are placed in areas where solder cracks are most likely to occur (central area), as these elements can withstand the resulting temperature variations and potential crack propagation. This placement strategy compensates for the reliability degradation caused by solder cracks while maintaining the manufacturing simplicity of using solder joining material.
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 reliability and cooling efficiency of the semiconductor device by isolating the silicon elements from heat cycle-induced cracks, ensuring stable operation at high temperatures and maintaining the semiconductor device's performance after repeated heat cycles.
Implementation Method 1
heat is conducted from the switching element through the laminated substrate to the cooling plate
Implementation Method 2
the metal board and the cooling plate being joined by using a joining material
Data Source
AI summary
A semiconductor device includes a cooling plate made of metal, one or more laminated substrates each formed by laminating a circuit board, an insulating board, and a metal board, and one or more first semiconductor elements each made of a wide-band-gap semiconductor and disposed over outer peripheral edge portions of the circuit board. The metal board and the cooling plate are joined by the use of a joining material. As a result, even if temperature rises due to the operation of the one or more first semiconductor elements and heat radiation is not performed properly, the one or more first semiconductor elements operate stably.