Power Module Reinforcing Structure for Ceramic Substrate Cracking
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Solution Overview
Problem
Power modules face reliability issues due to stress concentration and cracking risks in the ceramic substrate, which are exacerbated by the use of high thermally conductive materials with low mechanical strength, failing to meet long-term reliability requirements.
Innovation Solution
A reinforcing structure is integrated into the thermally conductive base plate, enclosing a containing space with the first metal layer, and filled with a molding body to distribute stress and reduce cracking risks, enhancing the ceramic substrate's support and improving the power module's reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a high thermally conductive ceramic substrate is used, then heat dissipation capability is improved, but mechanical strength decreases and risk of layering or cracking increases
Solution Approach 1:
The patent uses a composite structure combining ceramic insulation layer with metal layers (first metal layer and second metal layer) to create a ceramic metal composite substrate. This composite structure maintains high thermal conductivity through the metal layers while the ceramic layer provides electrical insulation, and the combined structure improves mechanical strength and crack resistance compared to pure ceramic substrates
Solution Approach 2:
The patent applies different materials with different properties to different layers of the substrate structure. The ceramic insulation layer provides thermal and electrical insulation properties, while the metal layers provide mechanical strength and electrical conductivity. This local differentiation of material properties allows the substrate to simultaneously achieve heat dissipation, mechanical strength, and electrical insulation
2Ease of manufacture
If the outer edge of the ceramic insulation layer protrudes relative to the lower copper layer, then manufacturing flexibility is improved, but stress concentration increases at the joint
Solution Approach 1:
The patent replaces the sharp corner geometry with a rounded corner structure. The rounded corners of the first metal layer and the ceramic insulation layer create a gradual transition zone that distributes stress more evenly, eliminating the stress concentration points that would occur at sharp corners while still allowing the ceramic insulation layer to protrude for manufacturing flexibility
3Stability of the object's composition
If the molding body wraps the ceramic substrate and chip, then structural integrity is improved, but stress concentration on the ceramic substrate increases
Solution Approach 1:
The patent introduces a recessed portion in the molding body that is positioned to avoid direct contact with the ceramic insulation layer at critical stress points. This localized modification to the molding body structure allows the molding body to provide overall structural support and integrity while reducing concentrated stress on the ceramic substrate, particularly at the corners and edges where stress concentration would be most severe
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 reinforcing structure optimizes stress distribution, reduces the risk of cracking in the ceramic substrate, and enhances the long-term reliability of the power module by transferring stress concentrations away from the ceramic insulation layer.
Implementation Method 1
The molding body provides a support force for the surface that is of the first metal layer and that faces the thermally conductive base plate
Implementation Method 2
transfers a stress concentration position on the ceramic substrate from the joint between the side surface of the first metal layer and the insulation layer to the surface that is of the first metal layer and that faces the thermally conductive base plate
Implementation Method 3
heat generated when the power chip works is mainly dissipated externally by using the ceramic substrate and a thermally conductive base plate (BP)
Data Source
Figure 1~2
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AI summary
A power module and a power converter are provided. The power module includes a thermally conductive base plate, a connection layer, a ceramic substrate, and a chip that are sequentially stacked. A molding body wraps the ceramic substrate and the chip. The ceramic substrate includes an insulation layer and a first metal layer. The first metal layer is disposed between the insulation layer and the connection layer. A reinforcing structure is formed on a side that is of the thermally conductive base plate and that faces the ceramic substrate. The reinforcing structure is located on a side portion of the connection layer in a direction perpendicular to an arrangement direction of the thermally conductive base plate and the connection layer. A wall surface of the reinforcing structure and a surface that is of the first metal layer and that faces the thermally conductive base plate enclose a containing space. The molding body fills the containing space. The molding body in the containing space wraps the surface that is of the first metal layer and that faces the thermally conductive base plate and a joint between a side surface of the first metal layer and the insulation layer, and transfers a stress concentration position on the ceramic substrate from the joint between the side surface of the first metal layer and the insulation layer to the surface that is of the first metal layer and that faces the thermally conductive base plate. This reduces a risk of layering or cracking of the insulation layer and helps improve reliability of the power module.