Single In-Line Lead Power Module Parasitic Inductance
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Solution Overview
Problem
Conventional power modules experience high parasitic inductance during fast switching, leading to voltage overshoot, and lack over voltage and over temperature protection, which limits their high voltage and high current capabilities.
Innovation Solution
A molded semiconductor power module with single in-line leads, including a die paddle, power chips, gate drive and protection IC, bonding wires, and molding encapsulation, featuring a low voltage power lead with a lead portion and extension portion, and increased creepage distance through an isolation cutout, allowing for improved heat sink mounting and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional power module structure is used, then manufacturing is simple, but parasitic inductance is high causing voltage overshoot during fast switching
Solution Approach 1:
The patent transitions from a planar lead arrangement to a three-dimensional single in-line lead structure that extends vertically from the die paddle. This dimensional change allows the lead to achieve both low inductance through minimized current loop area and adequate creepage distance through vertical extension, resolving the contradiction between fast switching capability and voltage overshoot prevention.
Solution Approach 2:
The single in-line lead acts as an intermediary element that mediates between the low voltage power chip and the external circuit. By incorporating an extension portion that protrudes from the molding encapsulation, it provides both low inductance connection and sufficient creepage distance, eliminating the need for separate isolation structures while enabling fast switching with reduced voltage overshoot.
2Reliability
If isolation distance between high voltage and low voltage leads is increased, then over voltage protection is improved, but package size increases
Solution Approach 1:
The patent utilizes the vertical dimension by extending the low voltage lead portion above the molding encapsulation surface. This allows the creepage distance to be achieved in the vertical direction rather than requiring increased horizontal separation, thereby maintaining compact package size while providing adequate isolation for over voltage protection.
Solution Approach 2:
The single in-line lead features localized extension only where needed for creepage distance, while maintaining a compact footprint at the die paddle level. The extension portion provides the necessary isolation distance without expanding the overall package volume, achieving local quality optimization for voltage isolation.
3Temperature
If larger die paddle is used for better heat management, then heat dissipation is improved, but mounting stability decreases
Solution Approach 1:
The patent segments the lead structure into distinct portions: a lead portion embedded in the molding encapsulation for mechanical support and mounting stability, and an extension portion protruding for heat dissipation and creepage distance. This segmentation allows the larger die paddle to improve heat management while the segmented lead structure maintains mounting stability through its embedded portion.
Data Source
AI summary
A power module has a lead frame, a first power chip, a second power chip, a plurality of single in-line leads, a gate drive and protection integrated circuit (IC), a plurality of bonding wires and a molding encapsulation. The first and second power chips are attached to a top surface of the lead frame. The plurality of single in-line leads has a high voltage power lead, a low voltage power lead and a plurality of signal control leads. The low voltage power lead has a lead portion and an extension portion. The gate drive and protection IC is attached to the extension portion of the low voltage power lead. The molding encapsulation encloses the first and second power chips, the extension portion of the low voltage power lead, the gate drive and protection IC, the plurality of bonding wires and at least a majority portion of the lead frame.