Semiconductor Conductor Posts for Thermal Stress Management
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Solution Overview
Problem
High-power semiconductor devices, such as IGBT modules, face reliability issues due to thermal expansion coefficient differences between support plates and heat discharging plates, leading to heat strain and potential failure under repeated heat cycles.
Innovation Solution
The semiconductor device employs conductor posts made of materials with high heat conductivity (200 W/m-K or higher) and low Vickers hardness (65 or lower), designed to absorb thermal stress and maintain connection reliability, along with a structured connection method that includes flanges and specific shapes to enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin support plate is used, then ease of manufacture is improved, but thermal expansion coefficient difference with heat discharging plate increases causing heat strain and warpage
Solution Approach 1:
The patent changes the material parameter of the support plate from resin to aluminum alloy, which has a thermal expansion coefficient closer to ceramic heat discharging plates. This parameter change reduces thermal expansion differences during heat cycles, minimizing heat strain and warpage while maintaining manufacturability through standard aluminum processing techniques.
Solution Approach 2:
The patent employs a composite structure combining aluminum alloy support plate with ceramic heat discharging plate. This composite material approach allows each component to发挥 its advantages: the aluminum alloy provides thermal compatibility and flexibility, while the ceramic provides heat dissipation performance, together solving the reliability issue without sacrificing ease of manufacture.
2Reliability
If ceramic heat discharging plate is used, then thermal expansion coefficient matching is improved, but rigidity increases causing large strain in junctions
Solution Approach 1:
The patent changes the support plate material from rigid resin or ceramic to aluminum alloy, which has appropriate rigidity and thermal expansion properties. This parameter change reduces the strain concentration in junctions between conductor posts and IGBT elements during thermal cycles, preventing solder fatigue and connection failure while maintaining good thermal expansion matching with ceramic heat discharging plates.
3Strength
If conductor posts with high strength are used, then connection strength is improved, but resistance to thermal stress decreases
Solution Approach 1:
The patent changes the conductor post material properties by selecting aluminum alloy with appropriate hardness (65 or lower on Vickers scale) and high thermal conductivity (200 W/m-K or higher). This parameter change creates a balance where the conductor posts have sufficient mechanical strength for connection while maintaining flexibility and thermal conductivity to resist thermal stress during heat cycles, preventing brittleness and fatigue.
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 significantly improves durability against thermal stress and maintains reliable connections, enabling the semiconductor device to withstand long-term heat cycles without disconnection, as demonstrated by power cycle endurance tests.
Implementation Method 1
conductor posts made of materials with high heat conductivity (200 W/m-K or higher)
Implementation Method 2
thermal expansion coefficient differences between support plates and heat discharging plates, leading to heat strain
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A semiconductor device (101) comprises a support plate (30), a semiconductor element (10), and conductor posts (40) having a first end (41a) at one end and a second end (42a) at the other end. The second ends (42a) of the conductor posts (40) are connected to the semiconductor element (10). Furthermore, the conductor posts (40) are connected to the support plate (30) at a position on the side of the second end (42a) that is closer to the first end (41a). Here, the conductor posts (40) have a heat conductivity of 200 W/mK or higher and a Vickers hardness of 70 or lower.