Power Module Inductance Reduction via 3D Stacked IGBT
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Solution Overview
Problem
Conventional power modules experience high parasitic inductance around the output terminal, leading to excessive surge voltage during switching operations, which exceeds the withstand voltage of power semiconductor elements.
Innovation Solution
The power module design reduces parasitic inductance by electrically connecting the current discharge section of a positive power semiconductor element to the output terminal and the current suction section of a negative power semiconductor element, with the positive emitter conductor and negative collector conductor interconnected via aluminum wires, forming a shorter current path to minimize inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current path from the emitter electrode to the output terminal is extended to connect components, then electrical connection is achieved, but the inductance on the peripheral section of the output terminal increases
Solution Approach 1:
The patent transitions from a planar two-dimensional layout to a three-dimensional stacked configuration. The positive IGBT chip and negative IGBT chip are arranged in different layers vertically, with the emitter electrode of the positive IGBT directly connected to the collector electrode of the negative IGBT through vertical wire bonds. This spatial arrangement in three dimensions significantly shortens the current path length compared to a flat two-dimensional layout, thereby reducing parasitic inductance while maintaining reliable electrical connections.
Solution Approach 2:
The patent implements a nested structure where the emitter electrode of the positive IGBT chip is directly connected to the collector electrode of the negative IGBT chip through wire bonds, creating a compact nested current path. The aluminum foil layers are also nested between the chips, forming an integrated multi-layer structure that minimizes the peripheral length of the output terminal while maintaining all necessary electrical connections.
2Object-affected harmful factors
If the current path length is reduced to minimize inductance, then surge voltage is reduced, but the complexity of electrical connections increases
Solution Approach 1:
The patent merges multiple functions into a single integrated structure. The aluminum foil layers serve dual purposes: they act as current paths and simultaneously function as electrical connections between different components. The wire bonds connecting the emitter of the positive IGBT to the collector of the negative IGBT combine the functions of electrical connection and inductance reduction. This merging of functions simplifies the overall connection structure while achieving the goal of reducing surge voltage.
Solution Approach 2:
The patent employs composite material structures, specifically using aluminum foil layers combined with wire bonds to create an integrated current path. The aluminum foil provides a low-inductance planar connection, while the wire bonds provide vertical inter-layer connections. This composite approach optimizes the connection structure by combining the advantages of different materials and geometries, reducing complexity while minimizing surge voltage.
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 configuration effectively reduces the total inductance, thereby controlling the surge voltage below the semiconductor element's withstand voltage, enhancing the reliability and efficiency of the power module by reducing losses and noise.
Implementation Method 1
a current of several hundreds of amperes is switched, which causes an induced electromotive voltage (surge voltage) due to the parasitic inductance of the main circuit
Data Source
AI summary
The present invention provides a power module, power converter, and vehicular electric machine system capable of reducing inductance of a peripheral section of an output terminal in a power module, and additionally, reducing a surge voltage. A positive emitter conductor 3 connected to an emitter electrode of a positive power semiconductor element Mpu and an output terminal U are electrically interconnected by using a plurality of aluminum wires 7, a negative collector conductor 4 connected to a collector electrode of a negative power semiconductor element Mnu and the output terminal U are electrically interconnected by using a plurality of aluminum wires 9, and the positive emitter conductor 3 connected to the emitter electrode of the positive power semiconductor element Mpu and the negative collector conductor 4 connected to the collector electrode of the negative power semiconductor element Mnu are further electrically interconnected by using a plurality of aluminum wires 8.