Stacked GaN Half-Bridge Clips for Compact High-Current IPMs
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Solution Overview
Problem
High power circuitry in integrated power modules (IPMs) face challenges in reducing module sizes due to the need for large capacitors and thick aluminum bond wires, which require significant spacing, limiting further size reduction in compact system designs.
Innovation Solution
The use of nested metal clips with different heights for transistor source and drain connections, replacing traditional wedge bonding, allows for compact interconnections with reduced lateral spacing and improved current carrying capability, reducing common mode inductance and enabling smaller module footprints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thick aluminum bond wires with wedge bonding are used for high current connections, then current carrying capability is improved, but lateral spacing requirements increase due to tool size
Solution Approach 1:
The patent transitions from planar wedge bonding to a three-dimensional stacked clip configuration. Multiple metal clips are stacked vertically at the same lateral position, allowing high current connections to be made in the vertical dimension rather than requiring lateral spacing. This dimensional change enables compact module footprints while maintaining current carrying capability through multiple parallel clip connections.
Solution Approach 2:
The patent implements nested metal clips where smaller clips are positioned within or adjacent to larger clips in the vertical stack. This nesting arrangement allows multiple connection points to occupy the same lateral footprint while providing sufficient clearance for bonding operations. The nested configuration maximizes space utilization and enables high current connections without increasing module width.
2Reliability
If large capacitors are placed outside switching transistor dies, then circuit functionality is improved, but spacing requirements increase limiting size reduction
Solution Approach 1:
The patent relocates capacitor connections from lateral placement to vertical stacking using the stacked clip architecture. Capacitors can be positioned closer to the switching transistor dies in the lateral dimension while maintaining electrical connectivity through the vertical clip stack. This enables compact integration of large capacitors without increasing module footprint.
3Reliability
If wedge bonding tools are used for terminal connections, then reliable electrical connections are achieved, but additional spacing is required between connection points
Solution Approach 1:
The patent divides the bonding process into multiple smaller bonding operations on individual stacked clips rather than requiring a single large wedge bond. Each clip can be bonded separately with smaller bonding tools, eliminating the need for large spacing between connection points. This segmentation enables dense packing of connection points while maintaining reliable electrical connections.
Solution Approach 2:
The stacked metal clips serve as intermediary connection elements between the switching transistor terminals and the external circuit. These clips provide reliable electrical connections through multiple small bonding operations rather than requiring direct large-scale wedge bonding between distant points. The clips act as intermediate conductors that enable compact integration while maintaining connection reliability.
Data Source
AI summary
An electronic device includes a substrate having first and second conductive traces, a semiconductor die having a transistor with a first terminal and a second terminal, and first and second metal clips. The first metal clip has a first end portion coupled to the first terminal of the transistor, and a second end portion coupled to the first conductive trace of the substrate. The second metal clip has a first end portion coupled to the second terminal of the transistor and a second end portion coupled to the second conductive trace of the substrate, and a middle portion of the second metal clip is spaced apart from and at least partially overlying a portion of the first metal clip.