Reinforced Power Module Packaging for Ceramic Substrate Cracking
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Solution Overview
Problem
Power modules with high thermally conductive ceramic substrates face reliability issues due to low force strength and a high risk of layering or cracking, which cannot meet long-term reliability requirements.
Innovation Solution
A power module design featuring a thermally conductive base plate with reinforcing structures on its side facing the ceramic substrate, enclosing a containing space filled with a molding body, which redistributes stress and supports the ceramic substrate, reducing the risk of cracking and improving 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 force 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 the high thermal conductivity of the ceramic material while the metal layers provide enhanced mechanical strength and stress distribution, preventing cracking and layering of the brittle ceramic substrate during molding and operation.
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 leading to layering or cracking
Solution Approach 1:
The patent applies different structural qualities to different regions of the substrate. The ceramic insulation layer protrudes at the outer edge to provide manufacturing flexibility and insulation, while the metal layers extend beyond the ceramic edges at critical stress areas. This local differentiation allows the structure to have both manufacturing flexibility and stress resistance in different locations simultaneously.
Solution Approach 2:
The patent extends the metal layers in the horizontal dimension beyond the ceramic insulation layer edges, creating an overlapping structure. This dimensional extension allows the metal layers to provide stress distribution and mechanical support at the edges where the ceramic protrudes, preventing stress concentration while maintaining the protrusion's manufacturing benefits.
3Stability of the object's composition
If the molding body directly contacts the joint between the lower copper layer and ceramic insulation layer, then packaging integrity is improved, but stress concentration at the joint increases causing layering or cracking
Solution Approach 1:
The patent introduces the molding body as an intermediary element that fills the containing space and contacts the metal layers rather than directly contacting the vulnerable joint between the copper layer and ceramic insulation layer. The molding body acts as a stress-distributing medium that provides support without concentrating stress at the weak joint interface, thereby maintaining packaging integrity while protecting the joint from stress concentration.
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 optimizes stress distribution within the power module, reducing the risk of layering or cracking of the insulation layer and enhancing the long-term reliability of the power module.
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. In addition, the molding body 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.
Implementation Method 2
heat generated when the power chip works can be dissipated externally by using the ceramic substrate and a thermally conductive base plate (BP). Use of a high thermally conductive ceramic substrate can significantly improve a heat dissipation capability of the power module.
Data Source
AI summary
A 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.