Power Package Welding Structure for Larger Die Attach Area
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Solution Overview
Problem
The existing power package designs using rivet technology consume significant space on the heat sink, reduce the usable die attach area, and have time-consuming and costly manufacturing processes, limiting the size and efficiency of semiconductor packages.
Innovation Solution
The use of fabrication attach processes such as spot welding, laser welding, and ultrasonic welding to connect a lead frame to a heat sink without the need for rivets, allowing for a more efficient use of space and simplifying the manufacturing process by eliminating the need for cylindrical protrusions and mechanical fasteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rivet technology is used to connect the heat sink with the lead frame strip, then the connection is mechanically secure, but the space consumption on the heat sink increases and the usable die attach area is reduced
Solution Approach 1:
The patent removes the rivet component entirely from the connection system, replacing mechanical fastening with direct welding between the lead frame strip and heat sink. This extraction of the intermediate rivet element eliminates the space consumption and structural complexity while maintaining connection integrity through direct metallurgical bonding.
Solution Approach 2:
The patent merges the connection function directly into the welding process, combining the lead frame strip and heat sink into a single integrated structure through metallurgical bonding. This eliminates the need for separate fastening components and maximizes the usable area on the heat sink surface.
2Strength
If rivet technology is used to connect the heat sink with the lead frame strip, then the connection is mechanically secure, but the manufacturing process becomes time-consuming and costly
Solution Approach 1:
The patent replaces the mechanical riveting system with a thermal welding system. Instead of using mechanical force and deformation to create connections, the invention uses controlled heating to melt and fuse the lead frame strip directly to the heat sink, significantly reducing manufacturing steps and time while maintaining connection strength.
Solution Approach 2:
The patent extracts the intermediate rivet component and the associated mechanical fastening steps from the manufacturing process. This simplification eliminates multiple operations (hole punching, rivet insertion, deformation) and replaces them with a single welding operation, dramatically improving productivity and reducing costs.
3Strength
If rivets are placed further inside the package to accommodate thicker heat sinks, then the connection is secure, but the area available for placing active devices is reduced
Solution Approach 1:
The patent removes the rivet that would need to be positioned inside the package, replacing it with a welding process that can create secure connections at the periphery or surface of the heat sink. This extraction allows active devices to be placed in areas that would otherwise be occupied by internal rivet positioning.
Solution Approach 2:
The patent transitions from three-dimensional rivet placement (requiring depth penetration into the heat sink) to a surface-level welding process. This dimensional change allows connections to be made at the heat sink surface or periphery, maximizing the internal volume and area available for active device placement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the usable die attach area by approximately 40%, enhances manufacturing efficiency, and allows for larger semiconductor devices, improving power density and reducing production costs.
Implementation Method 1
The connection is configured as one of the following: a spot welded portion, a laser beam modified portion, a laser beam welded portion, an ultrasonic welded portion, an electric resistance welded portion, and a fused metal welded portion
Implementation Method 2
a laser beam modified portion, a laser beam welded portion
Implementation Method 3
an ultrasonic welded portion
Implementation Method 4
an electric resistance welded portion
Data Source
AI summary
A semiconductor package includes a metal submount; at least one transistor die arranged on said metal submount; and one or more metal contacts configured to be located adjacent said metal submount by a connection. The connection is configured as one of the following: a spot welded portion, a laser beam modified portion, a laser beam welded portion, an ultrasonic welded portion, an electric resistance welded portion, and a fused metal welded portion.