Resin Case Notch Groove for Power Semiconductor Stress Relief
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Solution Overview
Problem
Conventional power semiconductor modules experience stress concentration and cracking at corner portions due to differences in thermal expansion coefficients between the resin case and metal substrate, leading to reduced insulation and increased costs.
Innovation Solution
Incorporating a notch groove at the corner portions of the resin case with a width and length of 4% or more of the internal dimension, and an angle of 90 to 150 degrees, to disperse stress and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin case is used to enclose the stacked assembly, then insulation and protection are provided, but stress concentration and cracking occur at corner portions due to thermal expansion differences
Solution Approach 1:
The resin case is segmented by introducing notch grooves at the corner portions, dividing the continuous corner structure into sections that can accommodate thermal expansion differences, thereby reducing stress concentration while maintaining overall structural integrity and insulation
Solution Approach 2:
The corner portions of the resin case are given a different local structure by adding notch grooves, making these specific areas more flexible and stress-resistant while the rest of the case maintains its original insulating properties
2Volume of stationary object
If the resin case is made larger to accommodate the stacked assembly, then more space is available for components, but stress at corner portions increases leading to cracking
Solution Approach 1:
By segmenting the corner portions with notch grooves, the patent allows the resin case to maintain a larger overall volume for component accommodation while the segmented corners independently manage thermal stress, preventing cracking despite the increased size
3Ease of manufacture
If conventional resin materials are used, then production costs are lower, but the resin case is prone to cracking at corner portions due to stress concentration
Solution Approach 1:
The notch grooves are preliminarily formed in the resin case during manufacturing, pre-configuring the corner portions to accommodate future thermal expansion and stress, thereby allowing the use of conventional resin materials without compromising long-term reliability
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 notch groove effectively reduces stress at corner portions, enhancing insulation and package life, while allowing the use of conventional resin materials, thus lowering production costs.
Implementation Method 1
Conventional power semiconductor modules experience stress concentration and cracking at corner portions due to differences in thermal expansion coefficients between the resin case and metal substrate
Data Source
AI summary
A semiconductor device has a configuration in which a stacked assembly and a resin case are combined. The stacked assembly includes a semiconductor element, a stacked substrate on which the semiconductor element is mounted, and a metal substrate on which the stacked substrate is mounted. In the resin case, a notch groove is provided at a corner portion for reducing a stress. At least one of a width and a length of the notch groove is 2 mm or more.