Small-Outline TVS Package With Integrated Lead-Clip Assembly
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Solution Overview
Problem
The existing discrete power semiconductor packages, such as the SOD123FL, face challenges in reducing size while increasing power capability, with difficulties in the soldering process for the clip leading to yield losses and contamination of assembly machines due to overflow solder paste.
Innovation Solution
The design integrates the clip function into the right lead as a single unitary component, with both leads featuring bend arms and grooves to reduce bending stress and facilitate assembly, and a redesigned clip to minimize solder usage and improve manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SOD123FL package uses discrete lead frame, chip, and clip structure, then the package can support basic TVS diode functionality, but the package outline becomes too small causing soldering difficulties and yield losses
Solution Approach 1:
The patent merges the discrete lead frame, chip, and clip into an integrated lead frame assembly where the lead frame directly integrates the chip mounting structure and clip support functions. This consolidation eliminates the need for separate discrete components, improving soldering reliability by reducing the number of separate solder joints while maintaining the package's ability to support TVS diode functionality.
Solution Approach 2:
The lead frame is designed to perform multiple functions simultaneously: it serves as the electrical connection structure, the mechanical support for the chip, and the clip support structure. This multi-functionality reduces the overall device complexity by eliminating the need for separate discrete components while maintaining all necessary functions for TVS diode operation.
2Productivity
If the package uses multiple discrete components (lead frame, chip, clip), then basic functionality is achieved, but manufacturing efficiency decreases due to multiple solder points
Solution Approach 1:
By integrating the chip mounting structure and clip support into a single lead frame assembly, the patent reduces the number of separate soldering operations required. Instead of soldering separate lead frame, chip, and clip components independently, the integrated structure allows for consolidated soldering processes, thereby improving manufacturing efficiency and reducing the cumulative precision requirements across multiple solder joints.
3Ease of manufacture
If the package uses traditional discrete structure, then assembly is straightforward, but overflow solder paste contaminates the assembly machine guider causing manufacturing downtime
Solution Approach 1:
The patent redesigns the lead frame structure with integrated clip support and optimized solder joint geometry that contains the solder paste during the soldering process. The integrated structure creates natural containment features that prevent solder paste overflow, converting what would be a harmful contamination issue into a controlled manufacturing process with no spillage.
Data Source
AI summary
A discrete semiconductor package includes a semiconductor device, a left lead, and a right lead. The semiconductor device has a first side and a second side, the second side being opposite the first side. The left lead has a left terminal and a platform to support the semiconductor device on the first side. The right lead has a right terminal and a clip coin to support the semiconductor device on the second side.