Meltable Encapsulant Zones for Crack-Resistant Semiconductor Modules
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Solution Overview
Problem
Power modules face challenges in providing effective protection and electrical insulation due to harsh environmental conditions and heat generation, leading to issues like cracks and delamination from coefficient of thermal expansion mismatch.
Innovation Solution
A semiconductor module with an electrically insulating encapsulant that is solid at room temperature but liquifies in response to operational heat, forming self-sealed liquified envelopes around heat-generating elements, thereby mitigating thermal stress and delamination while maintaining electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid encapsulant is used to protect and electrically insulate the power electronic circuitry, then electrical insulation and protection are provided, but cracks and delamination occur due to coefficient of thermal expansion mismatch under temperature variations
Solution Approach 1:
The encapsulant's physical state is changed from solid to liquid in response to temperature changes. The encapsulant material is selected to have a melting point within the operating temperature range, allowing it to transition from a solid state (providing electrical insulation and protection) to a liquid state (accommodating thermal expansion mismatches and preventing cracks and delamination).
Solution Approach 2:
The encapsulant transitions from a static solid state to a dynamic liquid state based on operating conditions. During operation, when temperature increases, the encapsulant melts and becomes liquid, allowing it to flow and accommodate differential thermal expansion between the power electronic circuitry and the encapsulant, thereby preventing mechanical failure while maintaining electrical insulation properties.
2Strength
If the encapsulant remains solid during operation, then structural stability is maintained, but heat transfer from the power semiconductor die is reduced
Solution Approach 1:
The encapsulant utilizes phase transition from solid to liquid in response to heat generated by the power semiconductor die. The melting point of the encapsulant is specifically selected to be within the operating temperature range, allowing it to transition to a liquid state during operation. In this liquid state, the encapsulant provides enhanced thermal conductivity for improved heat transfer while the surrounding solid encapsulant maintains structural stability and electrical insulation.
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 effectively reduces the risk of cracking and delamination, enhances heat transfer, and provides a reliable seal without the need for additional sealing mechanisms, ensuring the longevity and reliability of the semiconductor module.
Implementation Method 1
the electrically insulating encapsulant is configured to liquify without curing in response to heat generated by the power semiconductor die during operation
Implementation Method 2
a solid outer region of the electrically insulating encapsulant surrounds the liquified envelope
Data Source
AI summary
A semiconductor module includes a power electronics carrier including a metallization layer disposed on an electrically insulating substrate, a power semiconductor die mounted on the power electronics carrier, a housing that surrounds an interior volume over the power electronics carrier, an electrically insulating encapsulant within the interior volume that encapsulates the power semiconductor die, wherein the electrically insulating encapsulant is configured to transform during operation of the power semiconductor die such that a liquified envelope of the electrically insulating encapsulant surrounds the power semiconductor die and such that a solid outer region of the electrically insulating encapsulant surrounds the liquified envelope.