Power Module Stacked Power Terminals Parasitic Inductance
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Solution Overview
Problem
Conventional power modules suffer from high parasitic inductance due to single-layer lead-frame packaging, which affects switching characteristics and efficiency, and existing manufacturing methods struggle to meet packaging requirements when changes occur in the package structure.
Innovation Solution
A power module design featuring a connector with partially stacked positive and negative power terminals separated by an insulating layer, integrated with a signal terminal and connecting portion, and a manufacturing method that trims the connector to reduce parasitic inductance and improve positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signal terminals and power terminals are fanned out with a single-layer lead-frame, then the packaging process is simple, but the parasitic inductance in the power module becomes large
Solution Approach 1:
The patent transitions from a single-layer lead-frame structure to a multi-layer stacked structure where positive and negative power terminals are arranged in different layers. This dimensional change allows the current paths to be more compact and overlapping, significantly reducing the loop area and thus the parasitic inductance, while maintaining packaging simplicity through the integrated lead-frame design.
Solution Approach 2:
The patent employs a stacked configuration where the negative power terminal layer is positioned beneath the positive power terminal layer, creating a nested-like structure. This arrangement allows the terminals to be closely coupled in the vertical dimension, reducing the horizontal spread of current paths and minimizing the parasitic inductance without increasing overall package complexity.
2Object-generated harmful factors
If the package structure is changed to reduce parasitic inductance, then the parasitic inductance decreases, but the existing packaging process cannot meet the packaging requirements
Solution Approach 1:
The patent divides the power terminals into distinct positive and negative layers, each with specific functions. The positive power terminal layer and negative power terminal layer are separately designed and then assembled together, allowing independent optimization of each layer while maintaining overall manufacturability through standardized assembly processes.
Solution Approach 2:
The patent creates a composite lead-frame structure combining multiple metal layers with different electrical potential functions. The positive power terminal layer and negative power terminal layer are bonded together with precise alignment, forming a composite structure that achieves low parasitic inductance while remaining compatible with existing packaging capabilities through controlled assembly processes.
3Manufacturing precision
If the tolerance of the distance between the molding positioning hole and the terminal is ±30 um and the tolerance of the body size of the terminal is ±10 um, then the packaging precision is sufficient, but any change in the package structure makes the existing packaging process inadequate
Solution Approach 1:
The patent designs the lead-frame structure with universal features that can accommodate different package configurations. The molding positioning hole and terminal arrangements are designed to work with both traditional single-layer and new multi-layer structures, allowing the same packaging process to achieve the required ±30 um and ±10 um tolerances across different package designs without requiring complete process retooling.
Data Source
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AI summary
The present invention relates to a power module and a manufacturing method thereof. The power module includes: a group of switch elements, a molding part (7) and a connector. The group of switch elements includes pairs of switch elements. The molding part (7) molds the group of switch elements. The connector includes a signal terminal (403) and a power terminal respectively electrically connected to the signal end and power end of the group of switch elements, and both fanned out from the molding part (7). The power terminal includes a positive power terminal (405), a negative power terminal (402) and an output power terminal (406). The positive power terminal (405) and the negative power terminal (402) are respectively a first metal layer and a second metal layer which are partially stacked, and an insulating layer (408) is disposed between the first metal layer and the second metal layer.