Aluminum-Silicon Carbide Composite Base Plate Warpage Control
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Solution Overview
Problem
Conventional heat dissipation structures for power modules face issues with thermal expansion coefficient mismatch between base plates and ceramic substrates, leading to crack formation and inadequate heat dissipation, and existing methods for shaping aluminum-silicon carbide composites result in inconsistent warpage and high fabrication costs.
Innovation Solution
A flat silicon carbide porous body impregnated with an aluminum alloy, where an aluminum layer is formed on one primary plane and ground to improve flatness, with controlled thickness to achieve a rectangular shape and specific warpage, and a Ni film is applied for enhanced thermal conductivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper base plate is used for heat dissipation, then thermal conductivity is improved, but thermal expansion coefficient mismatch causes solder layer cracks and reduces reliability
Solution Approach 1:
The invention changes the material composition parameters by using aluminum alloy (specifically Al-Si-Mg alloy) instead of copper for the base plate. This material substitution provides a thermal expansion coefficient that matches the ceramic substrate, eliminating solder layer cracks while maintaining adequate heat dissipation performance.
Solution Approach 2:
The invention employs composite material structure by combining aluminum alloy with silicon carbide particles dispersed throughout the base plate. This composite approach enhances the thermal conductivity of the aluminum alloy while maintaining the matched thermal expansion coefficient, thus resolving both the reliability and thermal expansion issues simultaneously.
2Reliability
If aluminum alloy-silicon carbide composite is used to match thermal expansion coefficient, then solder layer reliability is improved, but warpage control is insufficient and heat dissipation property deteriorates
Solution Approach 1:
The invention applies local quality control by dispersing silicon carbide particles non-uniformly within the aluminum alloy matrix and creating a specific layered structure with different aluminum alloy compositions. This local variation in material properties enables precise control of warpage while maintaining thermal expansion matching and heat dissipation performance.
Solution Approach 2:
The invention controls warpage by adjusting compositional parameters of the aluminum alloy, specifically controlling Si content at 2-12 mass% and Mg content at 0.5-3 mass%, along with particle size distribution of silicon carbide. These parameter optimizations enable warpage control within acceptable limits while maintaining reliability and heat dissipation.
3Shape
If base plate surface is ground to improve flatness, then heat dissipation property is improved, but manufacturing cost increases significantly
Solution Approach 1:
The invention applies preliminary action by controlling the microstructure and composition of the aluminum alloy during casting and solidification processes. This preliminary control of material properties enables the base plate to achieve adequate flatness and warpage control without requiring extensive post-manufacturing grinding operations, thus reducing manufacturing costs while maintaining heat dissipation performance.
Solution Approach 2:
The invention reduces manufacturing cost by optimizing alloy composition parameters (Si: 2-12 mass%, Mg: 0.5-3 mass%) and silicon carbide particle characteristics. These parameter optimizations enable the material to self-adjust during solidification to achieve acceptable flatness and warpage control, minimizing the need for expensive diamond grinding operations.
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 solution provides a base plate with low thermal expansion and high thermal conductivity, improving heat dissipation properties and reliability by reducing gaps between the base plate and heat dissipation fins, and ensuring consistent warpage and flatness for semiconductor elements.
Implementation Method 1
a flat silicon carbide porous body impregnated with an aluminum alloy
Implementation Method 2
an aluminum layer made of a metal containing aluminum as the main component formed on one primary plane (front surface), and its flatness can be improved by grinding an aluminum layer on the rear side
Implementation Method 3
a Ni film is applied for enhanced thermal conductivity and reliability
Implementation Method 4
efficient dissipation of such heat has become a problem to be solved... high thermal conductivity... heat dissipation property of entire module
Data Source
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AI summary
An aluminum-silicon carbide composite suitable for a base plate for power module is provided. A base plate for power module, comprising an aluminum-silicon carbide composite that is a flat plate-shaped silicon carbide porous body impregnated with a metal containing aluminum as the main component, and an aluminum layer made of a metal containing aluminum as the main component formed only on one of the principal planes of the composite, wherein a rear surface being the other one of principal planes of the aluminum-silicon carbide composite is exposed to the outside, and the shape of the exposed aluminum-silicon carbide composite is a rectangle or a rectangle from which portions encompassing holes in the peripheral portion are removed. Plating property is imparted to the composite by providing an aluminum layer on one principal plane of the composite, and the flatness of the composite was improved by grinding its rear surface so that the aluminum-silicon carbide composite is exposed to the outside, and further, the warpage shape after the rear surface is ground is controlled by controlling the thickness of the aluminum layer.