Inverter Packaging With Sintered Silver Heat Sink Bonding
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Solution Overview
Problem
Inverters used in electric vehicles face inefficiencies in heat dissipation and cost-effectiveness, particularly due to the challenges of connecting transistors to heat sinks without damaging the components and maintaining low impedance for efficient energy conversion from DC to AC.
Innovation Solution
The solution involves improved packaging and structural designs for inverters, including the use of sintered silver layers for heat dissipation, u-bend connectors to reduce thermal stresses, and specifically designed busbars to minimize impedance, along with double-sided independently actuated press blocks for uniform pressure application during sintering, ensuring efficient heat management and reliable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transistors are connected to heat sinks using conventional methods, then heat dissipation is achieved, but the components may be damaged and connections are unreliable
Solution Approach 1:
A sintered silver layer is introduced as an intermediary between the transistor package and the heat sink. This intermediate layer enables reliable thermal and electrical connection while preventing direct mechanical contact that could damage the transistor components, thus resolving the contradiction between connection reliability and component damage prevention
Solution Approach 2:
The connection method is changed from conventional mechanical fastening to sintering process. By controlling sintering parameters (temperature, pressure, time), a metallurgical bond is formed that provides both reliable connection and gentle handling, avoiding component damage while ensuring thermal contact
2Use of energy by moving object
If conventional busbars are used, then electrical connections are made, but impedance is high reducing energy conversion efficiency
Solution Approach 1:
The busbar geometry is optimized by changing its physical parameters - reducing thickness and increasing width to create a flatter profile. This parameter change reduces the electrical path length and cross-sectional area, thereby lowering impedance and improving energy conversion efficiency from DC to AC
3Temperature
If pressure is applied during sintering, then good thermal contact is formed, but thermal stresses may damage components
Solution Approach 1:
The sintered silver layer serves as a cushioning intermediate layer that absorbs and distributes the pressure applied during sintering. This beforehand cushioning prevents stress concentration that would otherwise damage the transistor package, while still enabling good thermal contact through the sintered connection
Solution Approach 2:
A composite structure is created combining the transistor package, sintered silver layer, and heat sink. The silver layer acts as a compliant material that accommodates thermal expansion differences and distributes mechanical stresses, protecting the brittle transistor components while maintaining thermal contact
4Ease of manufacture
If cost-effective materials are used, then production costs are reduced, but heat dissipation performance may be compromised
Solution Approach 1:
The thickness of the sintered silver layer is optimized to provide adequate thermal conduction without excessive material cost. By carefully controlling the layer thickness parameter, the design achieves cost-effective manufacturing while maintaining sufficient heat dissipation performance for inverter operation
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 approach enhances the thermal performance and reliability of inverters, allowing for more efficient energy conversion and longer lifespan while reducing production costs, making them suitable for industrial-scale manufacturing.
Implementation Method 1
the substrate or the cladding layer is sintered to the heat sink through a sintering layer comprising silver
Implementation Method 2
the substrate or the cladding layer is sintered to the heat sink through a sintering layer comprising silver
Data Source
AI summary
A transistor package comprising: a substrate; a first transistor in thermal contact with the substrate, wherein the transistor comprises a gate; the substrate sintered to a heat sink through a sintered layer; an encapsulant that at least partially encapsulates the first transistor; and a Kelvin connection to the transistor gate.