Power Semiconductor Module With Compressed Dielectric Cooling Layer
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Solution Overview
Problem
Power semiconductor modules face challenges with mechanical and thermo-mechanical stress due to differing thermal expansion coefficients and rigid solder joints, leading to increased thermal resistance and premature failure, which complicates miniaturization and increases costs.
Innovation Solution
A power semiconductor module is designed with a dielectric material layer that provides an electrically insulating and thermally conductive connection to a cooling element via a non-positive fit, eliminating the need for rigid connections and allowing for a thinner, more reliable structure with reduced stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ceramic substrate is made thicker to compensate for mechanical and thermo-mechanical stress, then the stress resistance is improved, but the thermal resistance between the power semiconductor elements and the heat sink increases
Solution Approach 1:
The patent introduces a flexible connection layer (adhesive layer or solder layer with specific properties) as an intermediary between the ceramic substrate and the heat sink. This intermediary layer accommodates thermal expansion differences while maintaining good thermal contact, thus resolving the contradiction between stress resistance and thermal resistance.
Solution Approach 2:
The patent changes the mechanical parameters of the connection layer (such as using a flexible adhesive instead of rigid solder, or optimizing solder layer thickness and composition) to reduce its rigidity. This allows the connection layer to absorb thermal stress while maintaining adequate thermal conductivity, thereby reducing both the required substrate thickness and the thermal resistance.
2Temperature
If larger chip surfaces are used to meet application requirements due to higher thermal resistance, then the thermal performance is improved, but the installation space increases
Solution Approach 1:
By changing the parameters of the connection layer (reducing its thickness, improving its thermal conductivity through material selection), the overall thermal resistance of the assembly is reduced. This allows the use of smaller chip surfaces while maintaining the required thermal performance, thus reducing installation space.
3Strength
If rigid solder joints are used to provide strong mechanical connection, then the mechanical strength is improved, but the service life decreases due to aging and thermal stress
Solution Approach 1:
The patent changes the material properties and structural parameters of the connection layer, transitioning from rigid solder joints to a more flexible connection system. This can involve using adhesive layers with appropriate elasticity, optimizing solder layer thickness, or creating a composite connection structure. These changes reduce the connection layer's susceptibility to thermal stress and aging, thereby extending service life while maintaining adequate mechanical strength.
Solution Approach 2:
The patent employs a composite connection structure combining different materials (such as adhesive layers, solder layers, and flexible interlayers) to achieve both mechanical strength and resistance to thermal stress. This composite approach allows the connection system to accommodate thermal expansion differences while maintaining strong mechanical bonding, thus improving reliability.
4Reliability
If additional connecting materials and thicker substrates are used to ensure reliability, then the service life is improved, but the manufacturing costs increase
Solution Approach 1:
The patent optimizes the parameters of existing materials and processes (such as reducing substrate thickness through improved connection layer design, optimizing solder layer composition and thickness, or selecting adhesives with better performance) to achieve the required reliability without adding more materials or increasing complexity, thus controlling manufacturing costs.
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 reduces mechanical and thermo-mechanical stress, enabling a thinner module with extended service life and lower costs by minimizing thermal resistance and eliminating the need for additional connecting materials.
Implementation Method 1
the dielectric material layer (8) which is connected in an electrically insulating and thermally conductive manner to a cooling element (10)
Implementation Method 2
the dielectric material layer being connected with a non-positive fit to the cooling element by means of a first force (F1) acting orthogonally to the surface (11) of the cooling element (10)
Data Source
AI summary
A power semiconductor module includes a power semiconductor element. In order to reduce the required installation space of the power semiconductor module and to increase the service of the power semiconductor module, the power semiconductor element is connected in an electrically insulating and thermally conductive manner to a cooling element via a dielectric material layer. The dielectric material layer is laid flat on a surface of the cooling element and force-lockingly connected to the cooling element by a first force acting orthogonal to the surface of the cooling element.