Power Electronic Substrate Edge Insulation Against Thermal Bending
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Solution Overview
Problem
Semiconductor modules face issues due to thermal expansion differences between power electronic substrates and molded bodies, leading to potential bending and cracking that affect electrical insulation properties.
Innovation Solution
A semiconductor module design featuring a power electronic substrate with a first and second conductive layer separated by an insulating layer, where the insulating layer protrudes beyond the conductive layers' contours with a thickness-to-length ratio of 0.8 or more, reducing bending stress and potential cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the power electronic substrate and molded body are assembled together, then the semiconductor module achieves structural integrity and functionality, but thermal expansion differences cause bending and cracking in the substrate
Solution Approach 1:
The insulating layer is designed with non-uniform thickness, protruding beyond the conductive layers at lateral sides by a nonzero protrusion. This local quality enhancement provides additional insulation coverage at critical stress concentration zones where thermal expansion differences cause bending, preventing cracks while maintaining overall structural integrity.
Solution Approach 2:
The insulating layer is pre-configured with a thickness-to-length ratio of 0.8 or more before assembly, creating a protective structure in advance that compensates for future thermal expansion stresses. This preliminary design ensures that when temperature changes occur during operation, the insulating layer is already positioned to prevent cracking and maintain electrical insulation.
2Strength
If temperature changes occur during soldering or sintering, then the semiconductor module is securely attached to the heatsink, but differential thermal expansion causes significant bending and cracks
Solution Approach 1:
The insulating layer protrudes at lateral sides of the power electronic substrate, creating localized reinforcement zones where bending stress concentrates during thermal expansion. This non-uniform thickness distribution provides targeted protection at critical areas while allowing the rest of the substrate to accommodate thermal stresses.
Solution Approach 2:
The insulating layer with thickness-to-length ratio of 0.8 or more acts as a pre-configured cushioning element that absorbs and distributes bending stresses before they can cause cracks. This protective structure is in place before thermal cycling occurs, preventing damage during subsequent soldering or sintering processes.
3Reliability
If the insulating layer thickness is increased to prevent cracks, then electrical insulation properties improve, but the complexity of the substrate structure increases
Solution Approach 1:
Instead of uniformly increasing the insulating layer thickness throughout the substrate, the invention applies additional thickness only at lateral sides where the insulating layer protrudes beyond the conductive layers. This localized approach enhances electrical insulation and crack resistance at critical areas without unnecessarily complicating the overall substrate structure.
Solution Approach 2:
The insulating layer is designed with a thickness-to-length ratio of 0.8 or more, which may appear excessive for insulation purposes alone. However, this partial excessive action at lateral sides provides dual benefits: sufficient electrical insulation and structural reinforcement against bending stresses, avoiding the need for even more complex structural modifications.
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 design effectively reduces bending stress and minimizes cracks in the insulating layer, enhancing the electrical insulation properties and reliability of the semiconductor module.
Implementation Method 1
the power electronic substrate and the molded body may exhibit a significant difference in their coefficients of thermal expansion. Therefore, a sufficient change in temperature, e.g. during or after soldering or sintering the semiconductor module to a heatsink, may cause significantly different amounts of thermal expansion or shrinkage
Data Source
AI summary
A semiconductor module includes: a power electronic substrate having a first conductive layer, a second conductive layer, and an insulating layer separating the first and second conductive layers; at least one semiconductor die arranged over the first conductive layer; and a molded body having a first side and an opposite second side. The molded body encapsulates the semiconductor die and partially encapsulates the power electronic substrate such that the second conductive layer is at least partially exposed from the second side of the molded body. The insulating layer protrudes beyond a contour of the first conductive layer and/or beyond a contour of the second conductive layer at lateral sides of the power electronic substrate by a nonzero protrusion. A ratio of a thickness of the insulating layer to a length of the protrusion is 0.8 or more.