Leadframe Semiconductor Package for Heat Dissipation and Cutting Stress
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Solution Overview
Problem
Conventional semiconductor devices face challenges in effectively dissipating heat from semiconductor elements while maintaining a compact package size and minimizing stress during the manufacturing process.
Innovation Solution
The semiconductor device incorporates a lead structure with specific geometric configurations, including recessed sections and angled third sections, covered by a resin section, which enhances heat dissipation and reduces stress during cutting, by optimizing the area ratio and angles to facilitate closer placement of leads without excessive bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the lead structure uses conventional flat configuration, then the manufacturing process is simple, but heat dissipation from the semiconductor element is insufficient
Solution Approach 1:
The lead structure is divided into multiple functional sections: a flat section for mounting, an inclined section for stress distribution, and a bent section for positioning. This segmentation allows each part to serve a specific function, improving heat dissipation through increased surface area while maintaining manufacturing simplicity through standardized geometric shapes.
Solution Approach 2:
The lead transitions from a conventional flat two-dimensional configuration to a three-dimensional structure with inclined and bent sections. This dimensional change increases the surface area available for heat dissipation and creates pathways for stress distribution, resolving the contradiction between heat dissipation efficiency and structural complexity.
2Area of stationary object
If the leads are placed closer together to reduce device size, then the package size is reduced, but stress concentration occurs during the cutting process
Solution Approach 1:
The lead structure is pre-designed with inclined and bent sections that create stress distribution pathways before the cutting process occurs. This preliminary structural configuration prevents stress concentration during cutting, allowing leads to be placed closer together without compromising structural integrity, thus reducing package size while managing stress.
Solution Approach 2:
Different sections of the lead are given different geometric properties: the flat section provides stability for mounting, the inclined section distributes stress during cutting, and the bent section enables precise positioning. This local differentiation of structural qualities allows close lead placement while preventing stress concentration at critical points.
3Reliability
If the lead structure includes inclined and bent sections, then heat dissipation and stress distribution are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies particular parameter ranges for the lead geometry: inclination angles between 30-60 degrees, bend radii between 0.5-2 mm, and section length ratios. By defining these parameter ranges, the design achieves improved stress distribution and heat dissipation while maintaining manufacturability, as the specified ranges are tolerable with conventional manufacturing processes.
Data Source
AI summary
A semiconductor device includes: semiconductor element; first lead having first section carrying the semiconductor element; second lead separated from the first lead and connected to the semiconductor element; and resin section covering the semiconductor element and portions of the first and second leads. The first section has first obverse surface and first reverse surface mutually facing away in a thickness direction. The semiconductor element has element obverse surface and element reverse surface mutually facing away in the thickness direction. The element reverse surface faces the first obverse surface. The resin section has resin obverse surface and resin reverse surface mutually facing away in the thickness direction. The first reverse surface is exposed from the resin reverse surface, and the area ratio of the first reverse surface to a region surrounded by the outer edge of the resin reverse surface is between 40% and 50%.