Semiconductor Package Lead Structure for Heat Sink Contact
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Solution Overview
Problem
Conventional semiconductor packages face challenges in achieving effective heat radiation due to the U-shaped bending portion of the lead terminal obstructing the heat sink's contact with the package, limiting heat dissipation and requiring larger heat sinks, which also suffer from reliability issues under vibration.
Innovation Solution
The semiconductor package design features terminals with at least two obtuse-angle bending portions that allow elastic deformation, ensuring proper contact with a heat sink and enabling adjustable height, reducing mounting stress, and allowing shared heat sinks among packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a U-shaped bending portion is formed in the lead terminal to prevent stress on soldered portions, then reliability is improved, but the bending portion protrudes above the package upper surface and obstructs heat sink contact
Solution Approach 1:
The bending portions are repositioned from protruding above the package surface to being located below the package surface. This dimensional change allows the heat sink to contact the upper surface directly without obstruction, while the bending portions remain functional for stress absorption within the package structure.
Solution Approach 2:
Instead of having the bending portion extend upward to protect the solder joint, the design inverts the approach by having the bending portions extend downward below the package surface. This inversion maintains the protective function while eliminating the obstruction to heat sink contact.
2Reliability
If the U-shaped bending portion is arranged higher than the upper surface of the package, then stress protection is achieved, but the heat sink cannot make proper contact with the package surface
Solution Approach 1:
The bending portions are repositioned from the vertical dimension (above package surface) to the horizontal dimension (below package surface), enabling both stress protection and proper heat sink contact simultaneously.
3Ease of manufacture
If conventional surface mounted type packages are used for small-capacity applications, then cost is reduced, but heat radiation capability is insufficient for higher output requirements
Solution Approach 1:
The design changes the geometric parameters of the terminals by providing multiple bending portions with specific configurations below the package surface. This allows the package to maintain its compact surface-mounted form factor while improving heat radiation capability through better heat sink contact and thermal pathways.
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 design achieves improved heat radiation properties, reduces package size and cost, enhances reliability by minimizing stress on soldered joints, and allows for flexible mounting configurations.
Implementation Method 1
the bending portions are respectively elastically deformed when a downward stress is applied to a heat radiation surface of the sealing resin with a distal end portion of each terminal fixed
Data Source
AI summary
A semiconductor package includes: a semiconductor chip; a plurality of terminals connected to the semiconductor chip; and insulating sealing resin sealing the semiconductor chip and parts of the plurality of terminals, wherein an upper surface of the sealing resin is a flat heat radiation surface, the plurality of terminals respectively protrude from first and second side surfaces of the sealing resin that oppose each other, a distal end portion of each terminal has a substrate bonding surface positioned below a lower surface of the sealing resin, each terminal includes at least two bending portions existing below the heat radiation surface and bent downward, and angles of the bending portions are obtuse angles.