Power Stage Clip Cavity Structure for Compact Low-Stress MOSFET Stacking
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Solution Overview
Problem
Power stage devices, such as DrMOS and eFuse devices, face issues with large component footprints and potential damage due to stress concentration, leading to malfunction and reduced lifespan.
Innovation Solution
A clip with a cavity and notches is used to stack components vertically, minimizing footprint and reducing stress concentration, allowing for larger dies and improved soldering, while using a metallic wettable material for electrical communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large die components are used in power stage devices, then the electrical performance and power handling capability are improved, but the footprint area on the board increases
Solution Approach 1:
The patent transitions from a planar arrangement to a three-dimensional stacked configuration. The die is positioned in a cavity of the lead frame, allowing vertical stacking above the MOSFET package. This dimensional change enables large die to be accommodated without increasing the board footprint, as the increased size is absorbed in the vertical dimension rather than the horizontal plane.
2Ease of manufacture
If traditional clips with sharp vertices are used, then the manufacturing simplicity is maintained, but stress concentration occurs on the MOSFET leading to damage and reduced lifespan
Solution Approach 1:
The patent modifies the local geometry of the lead frame by introducing notches at the corners of the cavity. These notches eliminate the sharp vertices that would otherwise create stress concentration points. The local quality change at the corner regions redistributes mechanical stress away from the MOSFET, improving reliability while maintaining the overall simplicity of the lead frame structure.
3Manufacturing precision
If the die is securely held in place during manufacture, then the manufacturing precision and quality are improved, but the clip structure becomes more complex
Solution Approach 1:
The patent utilizes the existing cavity structure of the lead frame to hold the die. The cavity acts as a natural receptacle that confines the die within its boundaries. This nesting approach provides secure positioning and containment of the die during manufacturing and operation, while avoiding the need for additional complex retaining structures or mechanisms.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The present disclosure relates to a clip for use with a power stage device. The clip comprises a first portion defining a first planar surface and a second portion connected to the first portion. The second portion comprises a second planar surface, a cavity defined in the second planar surface, and at least one notch in a perimeter of the second planar surface, wherein the at least one notch extends into the cavity. Further described are a power driver device comprising the clip of present disclosure, methods of forming the clip, and methods of forming a power driver device.