Thermal Dissipating Lead Frame for Semiconductor Hot Spot Management
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Solution Overview
Problem
High-density semiconductor packages face challenges in effectively dissipating heat generated at specific thermal hot spot regions, as existing techniques often compromise package cost or space and are not specifically directed towards thermal dissipation at these regions.
Innovation Solution
A lead frame design that identifies thermal hot spot regions on a semiconductor die and modifies the lead frame structure by positioning thermal dissipating lead fingers closer to these regions, ensuring they are the closest to the hot spots for efficient heat dissipation while maintaining structural integrity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal dissipation techniques such as thick die pads with conductive epoxies, high temperature solders, dedicated leads, heat sinks, or enlarged lead frame corner regions are used, then heat dissipation capability is improved, but package cost and space are compromised
Solution Approach 1:
The patent applies local quality by positioning specific lead fingers (thermal dissipating lead fingers) closer to the die pad at locations corresponding to thermal hot spot regions, while other lead fingers maintain their conventional spacing. This creates a localized thermal dissipation function without modifying the entire lead frame structure, thereby improving heat dissipation capability while minimizing impact on package cost and space.
Solution Approach 2:
The patent segments the lead frame into two functional groups: conventional lead fingers for electrical connection and thermal dissipating lead fingers for heat dissipation. This segmentation allows the thermal dissipation function to be performed by specific selected lead fingers without requiring modifications to the entire lead frame structure, thus reducing overall package complexity and cost.
2Temperature
If lead fingers are positioned closer to the die pad to improve thermal dissipation, then heat dissipation efficiency is improved, but the distance for encapsulation material injection is reduced
Solution Approach 1:
The patent applies local quality by selectively positioning only certain lead fingers (those corresponding to thermal hot spot regions) closer to the die pad, while other lead fingers maintain their conventional spacing. This ensures that thermal dissipation is optimized at critical locations while preserving adequate spacing elsewhere for proper encapsulation material injection and manufacturing.
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 reduces the need for costly power dissipation techniques and effectively dissipates heat from hot spot regions, maintaining a suitable distance between lead fingers and the die pad to allow for encapsulation material injection, thereby improving package reliability and structural integrity.
Implementation Method 1
at least one thermal dissipating lead finger selected from the plurality of lead fingers that has a proximal end closer to the edge of the die pad than proximal ends of lead fingers adjacent to the at least one thermal dissipating lead finger
Data Source
AI summary
A lead frame for assembling a semiconductor device has a die pad surrounded by lead fingers. Each of the lead fingers has a proximal end close to but spaced from an edge of the die pad and a distal end farther from the die pad. A semiconductor die is attached to a surface of the die pad. The die has die bonding pads on its upper surface that are electrically connected to the proximal ends of the lead fingers with bond wires. An encapsulation material covers the bond wires, semiconductor die and the proximal ends of the lead fingers. Prior to assembly, hot spots of the die are determined and the lead fingers closest to the hot spots are selected to project closer to the die than the other lead fingers. These longer lead fingers assist in dissipating the heat at the die hot spot.