Metal Substrate Edge Stress Relief for High-Voltage Power Modules
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Solution Overview
Problem
Conventional insulated metal substrates face challenges in providing stable functionality and reliability, particularly in high voltage applications, due to mechanical and thermo-mechanical stress leading to voids, cracks, delamination, and dielectric breakdown at the edges of circuit metallization.
Innovation Solution
A metal substrate structure with a stress relief structure, featuring recesses, protrusions, and structured edges, is integrated into the metal top layer to absorb and dissipate mechanical and thermo-mechanical stress, enhancing adhesion between the metal and dielectric layers, thereby preventing voids and cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulated metal substrates are used for semiconductor power modules, then the structure is simple and manufacturing is easy, but mechanical and thermo-mechanical stress causes voids, cracks, delamination, and partial discharge under high voltage conditions
Solution Approach 1:
The patent applies local quality by introducing stress relief structures specifically at the edge regions of the metal top layer, where mechanical and thermo-mechanical stress is most concentrated. These localized features (grooves, recesses, or holes) provide stress relief precisely where needed without requiring complex modifications to the entire substrate structure, thus improving reliability under high voltage while maintaining overall structural simplicity
Solution Approach 2:
The patent segments the metal top layer by introducing discontinuities in the form of stress relief structures (grooves, recesses, or holes) at the edges. This segmentation allows the metal layer to better accommodate thermal expansion and mechanical stress by creating controlled weak points that prevent crack propagation, thereby reducing delamination and partial discharge risks
2Strength
If the metal top layer is made stiff to improve mechanical strength, then structural integrity is enhanced, but stress concentration at edges increases leading to voids and cracks
Solution Approach 1:
The patent converts the harmful effect of stress concentration at rigid metal layer edges into a beneficial feature by introducing stress relief structures. These structures create controlled stress distribution patterns that prevent uncontrolled crack formation and delamination, effectively transforming the potential failure mechanism into a protective feature that enhances overall structural integrity
3Reliability
If edge regions of circuit metallization are left as-is, then manufacturing is straightforward, but mechanical and thermo-mechanical stress causes delamination and partial discharge
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the metal top layer at its edges through stress relief structures. By changing the edge geometry from continuous to discontinuous (with grooves, recesses, or holes), the structure's resistance to delamination and partial discharge is improved while maintaining compatibility with standard manufacturing processes
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 stress relief structure improves mechanical stability, reduces the risk of partial discharge and dielectric breakdown, and extends the module life, enabling reliable operation in high voltage applications while maintaining heat dissipation characteristics.
Implementation Method 1
The stress relief structure of the described metal substrate structure is specifically formed in the area of the edge to absorb or dissipate forces due to mechanical or thermos-mechanical stress
Implementation Method 2
The metal substrate structure further comprises a metal bottom layer and a dielectric layer which is coupled with both the metal top layer and the metal bottom layer and formed in between with respect to a stacking direction
Implementation Method 3
The stress relief structure also serves as an anchoring structure for improved adhesion between the metal top layer and the dielectric layer
Implementation Method 4
The metal top layer having at least one recess which is limited by an edge of the metal top layer, wherein the metal top layer further comprises at least one stress relief structure in an area adjacent to the edge
Data Source
Figure 1
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Figure 4~5
AI summary
A metal substrate structure (10) for a semiconductor power module comprises a metal top layer (11) having at least one recess which is limited by an edge (14) of the metal top layer (11), wherein the metal top layer (11) further comprises at least one stress relief structure in an area adjacent to the edge (14). The metal substrate structure (10) further comprises a metal bottom layer (13) and a dielectric layer (12) which is coupled with both the metal top layer (11) and the metal bottom layer (13) and formed in between with respect to a stacking direction (A).