Patterned Sintered Power Module Connection for Thermo-Mechanical Stress
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Solution Overview
Problem
Power modules experience unwanted deformations and potential damage due to internal thermo-mechanical stress caused by temperature variations, leading to issues like crack formation and delamination in sintered connections, which traditional sintered connections cannot adequately address.
Innovation Solution
A power module with a patterned sintered connection layer, where the sintering material covers only a portion of the connection area, creating subregions that act as compensating layers to distribute and reduce thermo-mechanical stress, with a ratio of uncovered to covered surfaces between 10% and 75%, and using silver or copper nano/micro-particles for enhanced reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-patterned sintered connection layer is used to mechanically join module components, then mechanical strength and reliability are improved, but internal thermo-mechanical stress causes unwanted deformations, crack formation, and delamination
Solution Approach 1:
The sintered connection layer is segmented into patterned regions and non-covered subregions, creating a distributed structure that localizes stress in specific areas while maintaining overall mechanical strength through the sintered material regions
Solution Approach 2:
Different regions of the connection layer are designed with different properties: sintered material regions provide mechanical strength and electrical conductivity, while non-covered subregions provide stress relief and flexibility, creating local quality variations that address both strength and stress concerns
2Stability of the object's composition
If the entire area of the connection layer is covered by sintering material, then mechanical stability is improved, but rigidity increases making the layer unable to compensate for thermo-mechanical stress
Solution Approach 1:
The connection layer is divided into discrete sintered material regions separated by non-covered subregions, allowing the structure to maintain stability through the sintered regions while gaining flexibility through the segmented design that can deform independently in each region
Solution Approach 2:
The patterned sintered connection layer creates a thin-film-like structure where the non-covered subregions act as flexible elements that can deform to accommodate thermal expansion and contraction, while the sintered material regions maintain structural integrity
3Strength
If the ratio of uncovered surfaces to sintered connection area is less than 10%, then mechanical strength is maintained, but the effect of reducing internal thermo-mechanical stress becomes negligible
Solution Approach 1:
The ratio of uncovered surface area to total connection area is optimized within the range of 10-75%, representing a critical parameter change that simultaneously provides sufficient stress relief pathways while maintaining adequate mechanical strength through the remaining sintered material
4Object-affected harmful factors
If the ratio of uncovered surfaces to sintered connection area is more than 75%, then stress reduction effect is maximized, but mechanical stability of the connection may not be ensured
Solution Approach 1:
The uncovered surface ratio is constrained to maximum 75% to prevent excessive stress relief that would compromise the structural integrity of the connection layer, maintaining an optimal balance between stress management and mechanical stability
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 patterned sintered connection layer significantly reduces internal thermo-mechanical stress, enhancing the reliability and longevity of the power module by distributing stress and improving the quality of sintered connections, while maintaining mechanical stability.
Implementation Method 1
Sintering is a well-suited method to establish mechanically strong and highly reliable joining connections. Sintered joining connections, which are prepared for example from silver or copper micro-particles or nano-particles
Data Source
Figure 1~2A
Figure 2B~2C
Figure 3A~3B
AI summary
A power module (10) comprising at least two module components (M) and at least one connection layer (5) is provided, wherein the at least one connection layer (5) is formed along a vertical direction between the at least two module components (M) for mechanically connecting the at least two module components (M). The at least one connection layer (5) is a sintered connection layer forming a sintered connection between the at least two module components (M). Moreover, the at least one connection layer (5) is patterned, and in top view, an area (50) of the sintered connection is only partly covered by a sintering material, wherein subregions (50U) of the area (50), which are not covered by the sintering material, are bordered by one or several outer edges (50E) of the area (50). Furthermore, a ratio of surfaces of the not-covered subregions (50U) to the respective area (50) of the sintered connection is between 10 % and 75 %, inclusive. Moreover, a method for producing such a power module (10) is provided.