Variable-Thickness Substrate Metallization for Thermal Contact
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Solution Overview
Problem
Power semiconductor module arrangements experience deformation and cavity formation due to differing coefficients of thermal expansion (CTEs) among substrate and semiconductor elements, leading to reduced thermal contact and increased thermal resistance with heat sinks.
Innovation Solution
A substrate design featuring a dielectric insulation layer with metallization layers of varying thicknesses, including areas with different thicknesses to accommodate thermal expansion, preventing cavity formation and enhancing thermal contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform thickness metallization layers are used, then manufacturing is simple, but thermal contact is reduced and thermal resistance increases due to cavity formation from thermal expansion differences
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 among substrate components during heating and cooling cycles, preventing cavity formation on the lower mounting surface and maintaining reliable thermal contact with the heat sink.
Solution Approach 2:
The patent changes the thickness parameter of the second metallization layer from uniform to variable, creating regions of different thicknesses to accommodate thermal expansion differences. This parameter modification allows the metallization layer to adapt to thermal stresses while maintaining structural integrity and thermal contact quality.
2Manufacturing precision
If uniform thickness metallization layers are used, then manufacturing precision requirements are lower, but cavity formation occurs reducing thermal contact
Solution Approach 1:
The second metallization layer incorporates local thickness variations with first areas having a first thickness and second areas having a second thickness greater than the first thickness. This local quality differentiation directly addresses cavity formation by providing material compensation in regions prone to thermal expansion mismatch, eliminating the harmful effect while maintaining acceptable manufacturing precision standards.
Solution Approach 2:
The patent converts the harmful effect of thermal expansion differences into a beneficial design feature by intentionally creating non-uniform thickness distribution in the second metallization layer. The thickness variation that would normally be considered a manufacturing deviation is instead utilized to compensate for thermal stresses, transforming a potential defect into a functional advantage that prevents cavity formation.
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 thermal contact and reduces thermal resistance by compensating for thermal expansion, ensuring efficient heat dissipation and module performance.
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
AI summary
A substrate includes a dielectric insulation layer, a first metallization layer attached to a first side of the dielectric insulation layer, and a second metallization layer attached to a second side of the dielectric insulation layer opposite the first side. The second metallization layer includes one or more first areas and one or more second areas. The second metallization layer in the one or more first areas has a first thickness, and in the one or more second areas has a second thickness that is greater than the first thickness. Methods of producing the substrate are also described.