Variable-Thickness Metallized Substrate for Thermal Flatness
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Solution Overview
Problem
Power semiconductor module arrangements face issues due to differing coefficients of thermal expansion (CTEs) among substrate layers and semiconductor elements, leading to deformation and the formation of cavities that reduce thermal contact and increase thermal resistance between the substrate and heat sinks.
Innovation Solution
A substrate design featuring a dielectric insulation layer with a first metallization layer and a second metallization layer having varying thicknesses in specific areas to compensate for thermal expansion, either by increasing thickness in some areas or reducing it in others, thereby preventing cavity formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform thickness metallization layers are used, then manufacturing is simple, but thermal expansion differences cause deformation and cavity formation
Solution Approach 1:
The second metallization layer is designed with non-uniform thickness, featuring first areas with a first thickness and second areas with a second thickness that is greater than the first thickness. This local variation in thickness compensates for differential thermal expansion in different regions of the substrate, preventing cavity formation while maintaining manufacturing feasibility through selective deposition or additive processes.
2Adaptability or versatility
If different materials with different CTEs are used, then functional requirements are met, but deformation occurs during cooling
Solution Approach 1:
The patent explicitly addresses thermal expansion by designing the second metallization layer with varying thickness to compensate for differential thermal expansion between the substrate layer and semiconductor elements. The thicker regions in second areas provide additional material that expands more during heating and contracts less during cooling, maintaining substrate flatness despite using materials with different coefficients of thermal expansion.
3Reliability
If cavity formation is prevented, then thermal contact is improved, but manufacturing complexity increases
Solution Approach 1:
The patent changes the thickness parameter of the second metallization layer from uniform to non-uniform, creating first areas with a first thickness and second areas with a greater second thickness. This parameter variation is strategically implemented to prevent cavity formation and improve thermal contact, while the complexity increase is managed through controlled deposition or additive manufacturing techniques that can efficiently create the required thickness profile.
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 substrate design maintains a flat surface and enhances thermal contact with heat sinks, reducing thermal resistance and ensuring stable operation of the power semiconductor module.
Implementation Method 1
The different elements generally comprise different materials and therefore have different coefficients of thermal expansion CTE. Due to the different CTEs of the different elements, e.g., the substrate layer, the first and second metallization layers, and the semiconductor elements, at least some of the elements may deform during assembly of the power semiconductor module arrangement.
Data Source
Figure 1~3
Figure 4~5C
AI summary
A substrate (10) comprises a dielectric insulation layer (11), a first metallization layer (111) attached to a first side of the dielectric insulation layer (11), and a second metallization layer (112) attached to a second side of the dielectric insulation layer (11) opposite the first side, wherein the second metallization layer (112) comprises one or more first areas (A) and one or more second areas (B), wherein the second metallization layer (112) in the one or more first areas (A) has a first thickness (dA), and in the one or more second areas (B) has a second thickness (dB) that is greater than the first thickness (dA).