Power Stage Clip Notch-and-Cavity Layout for Compact MOSFET Packaging
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Solution Overview
Problem
Power stage devices, such as DrMOS and eFuse, face challenges due to large component footprints and potential damage from high-stress concentration points, leading to malfunction and reduced lifespan.
Innovation Solution
A clip with a cavity and notches is designed to hold components in place, allowing vertical stacking and reducing stress concentration, while being formed from a wettable material for direct soldering and electrical communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional power stage devices use large die and MOSFET components arranged side by side, then electrical functionality is achieved, but the footprint on the board increases
Solution Approach 1:
The patent transitions from a planar side-by-side arrangement of die and MOSFET components to a vertical three-dimensional stacking configuration. The die is positioned above the MOSFET package, utilizing the vertical dimension to reduce the horizontal board footprint while maintaining all necessary electrical connections through adapted lead frame structures.
Solution Approach 2:
The die is nested within the MOSFET package structure, with the die cavity providing a housing that contains the die component. This nesting arrangement allows the smaller die to be integrated within the larger MOSFET package envelope, further minimizing the overall device footprint and enabling compact integration.
2Reliability
If traditional clips have sharp or pointed vertices to define component boundaries, then manufacturing is simplified, but high-stress concentration points are created that can damage the MOSFET
Solution Approach 1:
The patent replaces sharp vertices and angular features in the clip and lead frame structures with curved or rounded geometries. This curvature eliminates stress concentration points that would otherwise exist at sharp corners, distributing mechanical stresses more evenly across the MOSFET package and improving reliability without significantly complicating the manufacturing process.
3Manufacturing precision
If the die is allowed to move freely during manufacture, then assembly flexibility is maintained, but the die position becomes inconsistent leading to quality issues
Solution Approach 1:
The patent incorporates preliminary positioning features into the clip and lead frame structures before the die placement operation. These pre-formed guides, recesses, or alignment features constrain the die to specific locations during the assembly process, ensuring consistent positioning and placement accuracy while still allowing for straightforward assembly operations.
Data Source
AI summary
A clip for use with a power stage device has a first portion defining a first planar surface and a second portion connected to the first portion. The second portion has 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. The at least one notch extends into the cavity. A power driver device can include such a clip. A method of forming a clip for use with a power stage device includes providing a frame that has a first planar portion and a second planar portion connected to the first planar portion; stamping a cavity into the second planar portion; and providing at least one notch into a perimeter of the second portion that extends into the cavity.