Multi-die Package Heat Spreader with Varying Fin Lengths
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Solution Overview
Problem
As semiconductor devices with multiple stacked dies face increasing heat dissipation challenges due to higher operating frequencies and increased package density, conventional heat spreaders and sinks are inadequate in managing uneven thermal energy distribution.
Innovation Solution
A semiconductor device design featuring a lid with varying length fins extending into a cavity, encapsulating stacked dies, and filled with a thermal interface material that enhances heat dissipation by distributing thermal energy uniformly across the substrate and fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple dies are stacked to increase package density, then transistor count and performance are improved, but heat dissipation becomes more difficult due to uneven thermal energy distribution
Solution Approach 1:
The heat spreader is designed with non-uniform thickness, creating varying thermal mass distribution across different regions. Thicker regions are positioned over high-heat-generation areas (die locations) to absorb and redistribute thermal energy, while thinner regions are placed in lower-heat areas, optimizing heat dissipation efficiency throughout the package.
Solution Approach 2:
The heat spreader employs an asymmetric thickness profile rather than a uniform design. This asymmetric structure allows different portions of the heat spreader to serve different thermal management functions, with thicker sections providing greater thermal capacity where needed most, directly addressing the uneven thermal energy distribution problem.
2Loss of energy
If conventional heat spreaders are used, then heat dissipation is provided, but the relative distribution of thermal energy remains uneven
Solution Approach 1:
The heat spreader is designed with non-uniform thickness, creating varying thermal mass distribution across different regions. Thicker regions are positioned over high-heat-generation areas (die locations) to absorb and redistribute thermal energy, while thinner regions are placed in lower-heat areas, optimizing heat dissipation efficiency throughout the package.
Solution Approach 2:
The thickness parameter of the heat spreader is varied spatially to change its thermal mass distribution. This parameter modification allows the heat spreader to better match the thermal load distribution from stacked dies, converting an uniform parameter design into a non-uniform one that optimizes heat dissipation.
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
The solution effectively addresses the heat dissipation issue by uniformly distributing heat generated by multiple dies, improving thermal management and allowing for efficient transfer of heat to the atmosphere through the substrate and fins.
Implementation Method 1
a thermal interface material fills the remainder of the cavity and is in thermal communication with both dies, the substrate and the fins
Implementation Method 2
A lid having a plurality of fins extending downwardly into the cavity is mounted on the substrate to encapsulate the semiconductor dies
Data Source
AI summary
A semiconductor device includes first and second stacked semiconductor dies on a substrate. A lid having a plurality of fins extending downwardly into the cavity is mounted on the substrate to encapsulate the semiconductor dies. At least some of the fins are longer than other ones of said fins. The lid is attached to the substrate, with the longer fins extending downwardly above a region of the substrate not occupied by the first die. The shorter fins extend downwardly above a region of said first die not covered by said second die. A thermal interface material fills the remainder of the cavity and is in thermal communication with both dies, the substrate and the fins. The lid may be molded from metal. The lid may be bonded to the topmost die, using a thermal bonding material that may be liquid metal, or the like.