Power Semiconductor Bonding Structure for Thermal Crack Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power semiconductor modules and power conversion apparatuses face challenges in extending their lifespan due to thermal cycles causing cracks that can propagate through bonding layers, leading to device failure.
Innovation Solution
A power semiconductor module design featuring a circuit substrate, power semiconductor device, and bonding portions with specific metal members and bonding layers, where the 0.2% offset yield strength of the first metal member is smaller than that of the second metal member and the bonding layer, preventing crack propagation by selectively generating cracks in the first metal member distal to the semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding layer is used to bond metal members in a power semiconductor module, then the module can withstand thermal cycles, but cracks may propagate through the bonding layer leading to device failure
Solution Approach 1:
The patent applies local quality by creating a gradient in yield strength across different metal members. The first metal member has lower yield strength than the second metal member, so that under thermal stress, the first metal member yields and absorbs energy locally, preventing crack propagation to the bonding layer and semiconductor device. This localized deformation protects the critical components while allowing the module to withstand thermal cycling.
Solution Approach 2:
The patent implements beforehand cushioning by designing the first metal member with lower yield strength to act as a sacrificial element. This member is positioned between the bonding layer and the external environment, so it deforms first under thermal stress, cushioning the bonding layer and semiconductor device from the full impact of thermal cycles. This pre-planned deformation path extends module lifespan by protecting critical components.
2Reliability
If the 0.2% offset yield strength of the first metal member is made smaller than that of the second metal member, then cracks are selectively generated in the first metal member preventing them from reaching the semiconductor device, but the structural strength of the bonding portion is reduced
Solution Approach 1:
The patent applies local quality by creating a gradient in yield strength across different metal members. The first metal member has lower yield strength than the second metal member, so that under thermal stress, the first metal member yields and absorbs energy locally, preventing crack propagation to the bonding layer and semiconductor device. This localized deformation protects the critical components while allowing the module to withstand thermal cycling.
Solution Approach 2:
The patent implements this principle by making the first metal member a sacrificial, short-living component that is intentionally designed to fail first. This disposable element absorbs the damage from thermal cycling through plastic deformation, protecting the more valuable semiconductor device and bonding layer. The first metal member serves its protective function and then deforms, but this controlled deformation prevents catastrophic failure of the entire module.
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 extends the lifespan of power semiconductor modules and power conversion apparatuses by preventing crack development in the semiconductor device, even under thermal cycles, through controlled crack generation in the first metal member, thereby enhancing reliability and reducing maintenance costs.
Implementation Method 1
a bonding layer that bonds the first metal member and the second metal member to each other
Implementation Method 2
0.2% offset yield strength of the first metal member is smaller than the 0.2% offset yield strength of the second metal member
Data Source
AI summary
A power semiconductor module includes a circuit substrate, a power semiconductor device including a semiconductor substrate, and at least one bonding portion. The at least one bonding portion includes a first metal member distal to the semiconductor substrate, a second metal member proximal to the semiconductor substrate, and a bonding layer that bonds the first metal member and the second metal member to each other. At an identical temperature, 0.2% offset yield strength of the first metal member is smaller than the 0.2% offset yield strength of the second metal member and is smaller than shear strength of the bonding layer.