Power Module Housing Lid for Thermal Stress Management
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Solution Overview
Problem
Existing power modules face challenges in achieving optimal heat radiation performance, connection reliability, and absorbing component height variance, while also risking stress during assembly due to difficulties in applying the correct pressing force for heat dissipation.
Innovation Solution
A power module design featuring a housing case with a heat sink and lead frames, where the lead frames are coupled to power semiconductor devices with metal joining material, and a sealing resin, with insulating members that vary in thickness to absorb stress and ensure proper contact, allowing for efficient heat dissipation and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the pressing force is increased to improve heat radiation performance, then heat dissipation efficiency is improved, but the power module may be damaged
Solution Approach 1:
A lid is introduced as an intermediary component between the housing cover and the power module. The lid receives the pressing force from the housing cover and distributes it uniformly across the power module surface through its larger contact area, preventing localized stress concentration that could damage the module while still ensuring adequate thermal contact for heat radiation.
Solution Approach 2:
The pressing force is controlled by adjusting the fit between the housing cover and housing base, transforming the assembly process into a parameter-controlled operation. By designing the housing dimensions to provide a specific interference fit, the appropriate pressing force is automatically applied without requiring complex adjustment mechanisms or risking over-compression.
2Strength
If the pressing force is decreased to protect the power module, then module damage is prevented, but heat radiation performance is degraded
Solution Approach 1:
The lid serves as a force distribution intermediary that allows using a larger overall pressing force from the housing cover without damaging the power module. The lid's larger surface area distributes the load, enabling sufficient contact pressure for heat radiation while protecting the module from excessive localized stress.
Solution Approach 2:
The lid performs multiple functions simultaneously: it acts as a thermal conduction path for heat radiation, a mechanical protective element that distributes pressing force, and a structural component that bridges the housing cover and power module. This multi-functionality resolves the contradiction by enabling both protection and heat dissipation.
3Temperature
If precise contact between lid and power module is required for heat radiation, then heat dissipation is improved, but assembly difficulty and pressing force control become problematic
Solution Approach 1:
The housing cover and housing base are designed with complementary dimensions that create a self-adjusting pressing mechanism. When assembled, the interference fit between these components automatically applies the necessary pressing force to ensure contact between the lid and power module, eliminating the need for precise manual adjustment or complex assembly procedures.
Solution Approach 2:
The lid acts as a mediator that transforms the assembly process. Instead of requiring direct precise alignment between the housing cover and power module, the lid provides a larger, more forgiving interface that automatically ensures adequate contact when the housing components are assembled with standard tolerances.
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 enhances heat radiation performance, improves connection reliability, and effectively absorbs component height variance, reducing stress during assembly and maintaining efficient heat dissipation.
Implementation Method 1
heat dissipated from power semiconductor devices is radiated to the surfaces of the case and lid
Implementation Method 2
heat dissipated from power semiconductor devices is radiated to the surfaces of the case and lid
Data Source
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AI summary
A power module includes a power unit equipped with plural power semiconductor devices, heat sinks, and a housing case. The power unit includes the power semiconductor devices, lead frames, and a sealing resin. The lead frames are coupled to the surfaces of each of the power semiconductor devices, and parts of the external surfaces of the upper and lower lead frames are bared out of the sealing resin. The housing case includes a housing base and a housing cover. The housing base, heat sink, power unit, heat sink, and housing cover are layered in that order. Assuming that S1 denotes the outline size of the housing base, S2 denotes the outline size of the housing cover, S3 denotes the size of the lead frame bared part of the power unit, the relationship of S1>S2>S3 is established. The housing cover is pressed and fixed to a receiving part of the housing base.