Bidirectional Switch Package Layout for Low Stray Inductance
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Solution Overview
Problem
Conventional bidirectional switches have high stray inductance due to the current loop passing through multiple pins, thin metal wires, and PCB wiring, which affects efficiency and increases production costs.
Innovation Solution
A package structure for a bidirectional switch that integrates semiconductor switches on a metal bottom plate with inner and outer pins, reducing stray inductance by integrating pins and using a lead frame process for efficient production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional package structure with separate anodes and cathodes is used, then the bidirectional switch can be manufactured with standard processes, but the stray inductance of the current loop is large which limits high-frequency performance
Solution Approach 1:
The patent merges the anode and cathode connections by having both terminals of the first semiconductor switch and both terminals of the second semiconductor switch connect to the same metal bottom plate. This creates a common reference plane that reduces the current loop area and thereby reduces stray inductance, improving high-frequency performance while maintaining manufacturability through standard packaging processes.
Solution Approach 2:
The patent transitions from a conventional planar layout to a three-dimensional stacked architecture where semiconductor switches are arranged vertically above the metal bottom plate with inner pins extending through multiple layers. This vertical arrangement minimizes the horizontal current loop area, reducing parasitic inductance while allowing standard manufacturing processes to be applied.
2Reliability
If the current loop area is reduced to decrease stray inductance, then high-frequency performance improves, but the layout design becomes more complex
Solution Approach 1:
The patent segments the bidirectional switch into modular components: first and second semiconductor switches, each with specific terminal connections to the metal bottom plate and inner pins. This segmentation allows independent optimization of each switch's connection path, minimizing current loop area for each device while maintaining overall structural organization that simplifies layout design.
Solution Approach 2:
The metal bottom plate serves as an intermediary element that provides a common connection point for multiple semiconductor terminals. By routing multiple connections through this central reference plane, the patent minimizes the area enclosed by current loops while maintaining a systematic and manufacturable layout structure.
Data Source
Figure 1~3A
Figure 3B~4A
Figure 4B~5
AI summary
This application provides a package structure of a bidirectional switch. The package structure includes a metal bottom plate, a first semiconductor switch, a second semiconductor switch, and a plurality of inner pins. The plurality of inner pins include a first inner pin, a second inner pin, a third inner pin, a fourth inner pin, and a fifth inner pin. In a specific implementation, the first semiconductor switch and the second semiconductor switch are disposed on the metal bottom plate, and both a first terminal of the first semiconductor switch and a first terminal of the second semiconductor switch are coupled to the metal bottom plate. A second terminal of the first semiconductor switch is coupled to the first inner pin. A third terminal of the first semiconductor switch is coupled to the second inner pin. A second terminal of the second semiconductor switch is coupled to the third inner pin. A third terminal of the second semiconductor switch is coupled to the fourth inner pin. The metal bottom plate is coupled to the fifth inner pin, and each inner pin is coupled to a same lead frame. By implementing this application, stray inductance of a current loop of the bidirectional switch can be reduced.