Semiconductor Clip Alignment Using Leadframe Peripheral Openings
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Solution Overview
Problem
The manufacturing of small power semiconductor devices with multiple channels faces challenges in producing clips with small dimensions and maintaining flat, even pads due to the difficulty in creating recesses and centering pins, leading to increased production costs and potential electrical performance degradation.
Innovation Solution
The use of additive manufacturing techniques, such as Laser Induced Forward Transfer (LIFT), to form clips with pins that utilize peripheral features of the leadframe for centering, eliminating the need for additional recesses on the pads and allowing for the production of smaller clips with improved centering and electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If recesses are created on leadframe pads to house clip pins for centering, then clip centering precision is improved, but pad flatness deteriorates and manufacturing complexity increases
Solution Approach 1:
The invention extracts the centering function from the pad structure by removing the recesses and instead utilizing peripheral features of the leadframe (such as edges or reference marks) for clip alignment. This eliminates the conflict between centering precision and pad flatness, as the pad surface remains completely flat while centering is achieved through a different mechanism.
Solution Approach 2:
The invention introduces an intermediary reference system based on peripheral features of the leadframe that mediates the centering process. Instead of directly forming recesses in the pads, the clip positioning is achieved through reference to external features, thereby preserving pad flatness while maintaining alignment precision.
2Volume of moving object
If clips are manufactured with small dimensions for multiple channels in small packages, then device miniaturization is improved, but manufacturing difficulty and handling difficulty increase
Solution Approach 1:
The invention merges the clip manufacturing process with the leadframe manufacturing process by forming clips directly from the leadframe material through punching or laser cutting. This integration eliminates the need for separate clip fabrication and handling, thereby maintaining ease of manufacture even as clip dimensions are reduced for multiple channels in small packages.
Solution Approach 2:
The leadframe material serves multiple functions: it provides the structural support, the electrical connections, and the clip material itself. By punching clips directly from the leadframe, the same material performs multiple roles, simplifying the overall manufacturing process despite the reduced size and increased number of clips required for multi-channel devices.
3Manufacturing precision
If multiple recesses are created on pads for centering, then clip centering is improved, but pad uniformity deteriorates
Solution Approach 1:
The invention removes the recesses from the pad structure entirely and extracts the centering function to peripheral reference features. This preserves the uniformity and electrical integrity of the pad surface while achieving accurate clip positioning through alternative means, thereby maintaining both precision and uniformity.
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 simplifies the manufacturing process, reduces production costs, and maintains electrical performance by using the leadframe's peripheral features for clip centering, enabling efficient production of small power semiconductor devices with multiple channels without compromising flatness or electrical integrity.
Implementation Method 1
Pins are also created extruding the material by punching with the purpose of centering the clip on the leadframe... such a clip may be provided with pins formed via additive manufacturing technique, optionally Laser Induced Forward Transfer (LIFT)
Data Source
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AI summary
A semiconductor die (14) is arranged at a die mounting location (12A) of an electrically conductive substrate (12). The electrically conductive substrate (12) comprises an array of electrically conductive leads (12B) having openings (282) at the periphery of the electrically conductive substrate (12). An electrically conductive clip (28) is arranged in a bridge-like position between the semiconductor die (14) and an electrically conductive lead (12B) in the array of electrically conductive leads (12B) to provide electrical coupling therebetween. The electrically conductive clip (28) has an end (200, 202) configured to be coupled to the electrically conductive lead (12B). The end (200, 202) of the electrically conductive clip (28) comprises: a planar proximal portion (202) configured to contact the electrically conductive lead (12B) proximally of the openings (282), and a distal portion (200) projecting beyond the proximal portion (202) distally thereof, the distal portion (200) provided with sculpturing (281) configured to engage the openings (282) to facilitate immobilizing the electrically conductive clip (18) in the bridge-like position between the semiconductor chip (14) and electrically conductive lead (12B).