Single Gauge Lead Frame Thermal Dissipation
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Solution Overview
Problem
Existing power semiconductor devices face challenges with thermal dissipation, increased manufacturing complexity, and cost due to dual gauge lead frames, additional structural elements, and solder bonds, which result in reduced thermal performance and reliability.
Innovation Solution
A single gauge lead frame is used, where the semiconductor die is directly attached to one level and the heat sink to another, with a molding compound encapsulating the die and part of the lead frame, allowing a portion of the heat sink to remain outside for enhanced thermal dissipation without increasing lead frame thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If dual gauge lead frame is used to increase heat sink thickness for better thermal dissipation, then thermal dissipation ability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The lead frame is segmented into two distinct thickness zones: a thicker heat sink portion for thermal dissipation and a thinner lead portion for electrical connection. This segmentation allows each part to be optimized for its specific function while using a single gauge material, avoiding the complexity of dual gauge manufacturing.
Solution Approach 2:
The lead frame exhibits local quality variation where the heat sink portion has greater thickness than the lead portion. This localized thickness variation enables improved thermal dissipation at the heat sink while maintaining manageable lead dimensions, all within a single gauge lead frame structure.
2Reliability
If additional structures are introduced to connect die to leads, then connection is achieved, but thermal resistance increases
Solution Approach 1:
The die connection structure is merged with the lead frame itself, eliminating the need for separate additional connecting structures. The lead frame serves both as the electrical connection pathway and as part of the thermal dissipation pathway, reducing thermal resistance while maintaining connection reliability.
3Strength
If ground pads and spacers are added to the structure, then structural integrity is improved, but thermal flow is inhibited
Solution Approach 1:
The lead frame serves as an intermediary structure that simultaneously provides structural integrity and maintains thermal flow pathways. By carefully designing the lead frame geometry, it acts as a mediator between the die and heat sink, ensuring both mechanical support and efficient thermal conduction without requiring separate ground pads or spacers that would block heat flow.
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 manufacturing, reduces variation and cost, and improves thermal performance by eliminating additional structural elements and solder bonds, leading to increased efficiency and reliability of power semiconductor devices.
Implementation Method 1
A molding compound encapsulates the semiconductor die and a portion of the lead frame
Implementation Method 2
the heat sink is attached to a second level of the lead frame... to increase the thermal dissipation ability of the heat sink
Implementation Method 3
a metal tab or heat sink with a hole, which may be used in mounting the package case to an external heat sink
Data Source
AI summary
In one embodiment the present invention includes a semiconductor power device. The semiconductor power device includes a single gauge lead frame, a semiconductor die, and a heat sink. The semiconductor die is attached to a first level of the lead frame. The heat sink is attached to a second level of the lead frame. A molding compound encapsulates the semiconductor die and a portion of the lead frame, such that a portion of the heat sink is outside of the molding compound. The resulting device may be efficiently manufactured as compared to dual gauge lead frame devices or devices where the semiconductor die is not attached to the lead frame.