Power Semiconductor Sealing Resin Cracking Prevention
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Solution Overview
Problem
Power semiconductor devices face reliability issues due to cracking of silicone gel sealing materials under extreme temperature variations, leading to reduced insulation reliability in both high and low temperature environments.
Innovation Solution
A silicone gel-sealed power semiconductor device is designed with a sealing resin that has a resin strength of 0.12 MPa or higher at room temperature, a microcrystallization temperature of −55° C. or lower, and a needle penetration of 30 to 50 after storage at 175° C. for 1000 hours, preventing cracking and enhancing heat resistance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional silicone gel with large thermal expansion coefficient is used for sealing, then the sealing material can be easily manufactured, but cracking occurs during temperature cycle tests due to thermal stress from expansion coefficient differences
Solution Approach 1:
The patent changes the physical and chemical parameters of the sealing resin by specifying precise property ranges: resin strength ≥0.12 MPa, microcrystallization temperature ≤−55° C., and needle penetration 30-50 after high-temperature storage. These parameter adjustments ensure the sealing material can withstand thermal stress without cracking while maintaining ease of manufacture
Solution Approach 2:
The invention uses a composite sealing resin formulation that combines multiple components to achieve the specified property ranges. This composite material approach allows the sealing resin to have both the required mechanical strength and thermal expansion characteristics that prevent cracking during temperature cycling
2Adaptability or versatility
If the use temperature range is expanded to −55° C. to 175° C., then the adaptability of the power semiconductor device is improved, but the sealing resin may crack under extreme temperature variations
Solution Approach 1:
The patent adjusts the sealing resin parameters to match the expanded temperature range: microcrystallization temperature ≤−55° C. prevents brittleness at low temperatures, while resin strength ≥0.12 MPa and controlled needle penetration maintain structural integrity at high temperatures up to 175° C.
Solution Approach 2:
The sealing resin is designed with beforehand cushioning properties where the microcrystallization temperature is set ≤−55° C. to prevent crystallization and subsequent cracking during low-temperature operation, and the resin strength is optimized to absorb thermal stress before it can cause damage
3Reliability
If high resin strength is used to prevent cracking, then the reliability is improved, but the sealing resin may become too rigid and crack under thermal stress
Solution Approach 1:
The patent optimizes the resin strength parameter to a specific range (≥0.12 MPa) rather than using maximum possible strength. This balanced parameter setting provides sufficient strength to prevent cracking while maintaining the flexibility needed to accommodate thermal expansion and contraction without brittle failure
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 suppresses cracking in temperature cycle tests and high temperature storage tests, providing power semiconductor devices with improved heat resistance and reliability across an expanded temperature range of −55° C. to 175° C.
Implementation Method 1
a microcrystallization temperature equal to or lower than −55° C.
Implementation Method 2
after storage at 175° C. for 1000 hours
Data Source
AI summary
A power semiconductor device including an insulating substrate having a metal layer formed on an upper surface thereof, a semiconductor element and a main electrode bonded to the metal layer, a metal wire connecting the metal layer with the semiconductor element, a metal member bonded to a lower surface side of the insulating substrate, a case member surrounding the insulating substrate and being in contact with a surface of the metal member bonded to the insulating substrate, and a sealing resin which fills a region surrounded by the metal member and the case member and has a resin strength of 0.12 MPa or higher at room temperature, a microcrystallization temperature of −55° C. or lower, and a needle penetration of 30 to 50 after storage at 175° C. for 1000 hours and seals the insulating substrate, the metal layer, the semiconductor element, the metal wire, and the main electrode.