Die Stack Thermal Management Using Barrier and Underfill
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Solution Overview
Problem
The increasing heat generation in small, high-speed semiconductor devices with multiple die stacks poses thermal management challenges due to obstructed thermal paths, inefficient heat dissipation, and the formation of voids and heat transfer barriers, which can lead to elevated die temperatures and malfunctioning packages.
Innovation Solution
Incorporating a barrier around the die stack to prevent the wicking and pooling of underfill material, enhancing thermal conductivity, and using thermal interface materials to improve heat transfer from the die to a heat sink, while also employing thermoelectric coolers for active heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple die are stacked to increase functionality and reduce device size, then device functionality and integration density are improved, but heat dissipation efficiency deteriorates due to obstructed thermal paths
Solution Approach 1:
The patent segments the thermal management system into multiple functional layers: thermal interface materials between individual die, underfill material filling gaps, and a dedicated heat spreader layer. This segmentation allows each layer to address specific thermal challenges in the stacked configuration, maintaining heat dissipation efficiency while enabling multi-die functionality.
Solution Approach 2:
The patent introduces thermal interface materials and underfill material as intermediary substances between die layers. These intermediaries improve thermal coupling and provide continuous thermal paths through the stacked structure, resolving the heat dissipation obstruction caused by multiple die interfaces while preserving the integrated functionality of the stack.
2Stability of the object's composition
If underfill material is applied to fill gaps between die, then structural stability is improved, but void formation and heat transfer barriers increase
Solution Approach 1:
The patent modifies the physical and chemical parameters of the underfill material, including its viscosity, thermal conductivity, and curing characteristics. By optimizing these parameters, the underfill material achieves both structural stabilization of the die stack and maintains effective heat transfer pathways, preventing void formation while preserving thermal reliability.
Solution Approach 2:
The patent employs composite material formulations for the underfill and thermal interface materials, combining materials with complementary properties. This creates a composite structure that simultaneously provides mechanical support and efficient thermal conduction, resolving the contradiction between structural stability and heat transfer efficiency.
3Volume of moving object
If device size is reduced to meet miniaturization goals, then device compactness is improved, but thermal management capability deteriorates
Solution Approach 1:
The patent transitions from planar heat dissipation to three-dimensional thermal management by implementing vertical thermal paths through the stacked die structure. Thermal interface materials and the heat spreader create heat conduction pathways in the vertical dimension, enabling effective thermal management in miniaturized devices where lateral heat dissipation space is limited.
Solution Approach 2:
The patent utilizes the controlled porous structure of underfill material to maintain thermal pathways while providing structural support. The porous composition allows for heat conduction through the filled gaps between die, enabling compact device design without sacrificing thermal management capability.
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 solution reduces void formation, enhances heat dissipation, and maintains die temperatures within recommended limits, improving the overall thermal performance and reliability of the semiconductor package.
Implementation Method 1
the barrier may be formed around a die stack to prevent wicking and pooling of an underfill material
Implementation Method 2
using thermal interface materials to improve heat transfer from the die to a heat sink
Implementation Method 3
employing thermoelectric coolers for active heat dissipation
Data Source
AI summary
Apparatuses and methods for heat transfer from packaged semiconductor die are described. For example, an apparatus may include a plurality of die in a stack, and a barrier in close proximity to at least an edge of each of the plurality of die. The apparatus may further include fill material in spaces between adjacent die of the plurality of die and in between the plurality of die and the barrier.