AlSiC Base Plate for Semiconductor Thermal Warping
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Solution Overview
Problem
Conventional semiconductor devices face issues such as substrate warping and cracking due to thermal expansion differences, leading to reliability concerns and challenges in downsizing, heat dissipation, and mounting complexity.
Innovation Solution
A semiconductor device design featuring an insulating substrate with a base plate having a lower coefficient of linear expansion than copper and a transfer mold resin with scooped shapes exposing base plate mounting holes, reducing thermal warping and enhancing adhesive strength, heat dissipation, and simplifying mounting processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a Cu base plate is used for high thermal conductivity, then heat dissipation is improved, but substrate warping and cracking occur due to thermal expansion difference
Solution Approach 1:
The base plate is constructed as a composite structure with a Cu core layer (high thermal conductivity) and an AlSiC outer layer (low thermal expansion coefficient). This composite design allows the device to benefit from both high heat dissipation capability and reduced thermal warping, resolving the contradiction between thermal performance and structural reliability.
Solution Approach 2:
The invention changes the material parameters of the base plate by selecting AlSiC with specific properties: thermal expansion coefficient of 5.7-6.5 ppm/°C (matching the insulating substrate) and thermal conductivity of 120-150 W/mK. These parameter optimizations enable simultaneous achievement of low warping and adequate heat dissipation.
2Power
If the insulating substrate size is increased for higher power handling, then power capacity is improved, but warping and cracking increase
Solution Approach 1:
The AlSiC base plate's low thermal expansion coefficient (5.7-6.5 ppm/°C) closely matches that of the insulating substrate, creating a composite structure with compatible thermal characteristics. This allows larger substrate sizes to be used for higher power handling without experiencing excessive warping or cracking.
3Reliability
If transfer mold resin with high adhesive strength is used, then bonding reliability is improved, but curing contraction causes substrate warping
Solution Approach 1:
The invention specifies transfer mold resin with a low coefficient of linear expansion (≤16 ppm/°C) to minimize curing contraction. This parameter optimization allows the resin to maintain high adhesive strength while causing minimal warping of the insulating substrate during the curing process.
4Volume of moving object
If semiconductor chip size is reduced for downsizing, then device compactness is improved, but junction reliability deteriorates due to thermal stress
Solution Approach 1:
The AlSiC base plate's thermal expansion coefficient (5.7-6.5 ppm/°C) closely matches that of the semiconductor chip, creating a compatible thermal environment. This allows smaller chip sizes to be used for device downsizing while maintaining junction reliability by reducing thermal stress during temperature cycles.
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
This design prevents substrate cracking, ensures reliable dielectric integrity, improves heat dissipation efficiency, and facilitates easier mounting with reduced fixture requirements, enhancing workability and cost-effectiveness.
Implementation Method 1
the coefficient of linear expansion of the base plate is lower than that of copper... In a cooling process after soldering the insulating substrate onto the Cu base plate, the Cu base plate and the insulating substrate contract. The contraction due to cooling is referred to as cooling contraction.
Implementation Method 2
the coefficient of linear expansion of the transfer mold resin is not higher than 16 ppm/° C... by using a resin having a coefficient of linear expansion lower than that of the liquid epoxy resin or the like used for the above-discussed case type semiconductor device, the semiconductor chip and the like are sealed by a transfer mold resin sealing method. With the transfer mold type, great adhesive strength can be achieved
Implementation Method 3
The base plate has such scooped shapes as to expose opposed short-side centers and the vicinity of the base plate, respectively... improves heat dissipation efficiency
Data Source
AI summary
A semiconductor device includes a base plate having one main surface joined to an insulating substrate on which a semiconductor chip and the like are mounted and a transfer mold resin which is so provided as to cover the one main surface of the base plate, the insulating substrate, the semiconductor chip, and the like and expose the other main surface of the base plate. The coefficient of linear expansion of the base plate is lower than that of copper and the coefficient of linear expansion of the transfer mold resin is not higher than 16 ppm/° C. The transfer mold resin has such scooped shapes as to expose opposed short-side centers and the vicinity of the base plate, respectively. The base plate has mounting holes in portions exposed by the scooped shapes of the transfer mold resin.