Embedded Heat Conductive Layers for Semiconductor Package Thermal Management
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Solution Overview
Problem
Semiconductor packages face challenges in heat dissipation due to the low coefficient of thermal expansion of molding compounds, especially for stacked dies, which results in inefficient heat transfer and increased thermal energy generation as performance improves.
Innovation Solution
Incorporating heat conductive layers with higher coefficients of thermal expansion than the molding compound on the back surfaces of semiconductor devices and connecting them to an external heat dissipation device, allowing for efficient heat transfer from the dies to the outside through these layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molding compound is used to encapsulate semiconductor devices, then the package structure is protected and electrically isolated, but heat dissipation efficiency deteriorates due to low coefficient of thermal expansion
Solution Approach 1:
The patent employs a composite material structure consisting of a molding compound layer and a heat conductive layer with different thermal properties. The molding compound provides protection and electrical isolation, while the heat conductive layer (with higher CTE than the molding compound) provides efficient heat dissipation. This composite structure resolves the contradiction by allowing each material to perform its specialized function without compromising the other.
Solution Approach 2:
The heat conductive layer is selectively positioned at the back surface of the semiconductor device where heat generation occurs. This local quality approach concentrates the heat dissipation function in the specific region where it is most needed, while the molding compound covers other areas for protection and electrical isolation. The local application of different material properties optimizes both protection and heat dissipation.
2Power
If semiconductor devices are stacked to improve performance, then processing power increases, but thermal energy generation increases and heat dissipation becomes more difficult
Solution Approach 1:
The patent segments the thermal management function by introducing a dedicated heat conductive layer that is embedded in the back surface of each semiconductor device in the stack. This segmentation allows heat to be managed at each device level rather than relying solely on the molding compound, effectively addressing the thermal challenges of stacked high-power devices.
Solution Approach 2:
The heat conductive layer acts as an intermediary between the semiconductor device and the external environment. It provides a thermal bridge that facilitates heat transfer from the device to the outside, enabling efficient thermal management in stacked device configurations where direct heat dissipation paths are limited.
3Temperature
If heat conductive layers with higher CTE than molding compound are used, then heat dissipation efficiency improves, but thermal expansion mismatch may cause stress
Solution Approach 1:
The patent deliberately changes the thermal expansion parameter by selecting a heat conductive layer material with a higher CTE than the molding compound. This parameter change prioritizes heat dissipation efficiency, and the resulting thermal expansion stress is managed through the layered structure design and material selection that accommodates the differential expansion.
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
Significantly improves heat dissipation efficiency by allowing quick transfer of heat generated from the semiconductor devices to the outside, effectively addressing the thermal management issues in semiconductor packages.
Implementation Method 1
a first heat conductive layer embedded in the first back surface of the first semiconductor device, a second heat conductive layer embedded in the second back surface of the second semiconductor device, and a third heat conductive layer disposed adjoining the first heat conductive layer and extending to the first active surface of the first semiconductor device
Implementation Method 2
Incorporating heat conductive layers with higher coefficients of thermal expansion than the molding compound on the back surfaces of semiconductor devices and connecting them to an external heat dissipation device
Data Source
AI summary
A semiconductor heat dissipation structure includes a first semiconductor device including a first active surface and a first back surface opposite to the first active surface, a second semiconductor device including a second active surface and a second back surface opposite to the second active surface, a first heat conductive layer embedded in the first back surface of the first semiconductor device, a second heat conductive layer embedded in the second back surface of the second semiconductor device, and a third heat conductive layer disposed adjoining the first heat conductive layer and extending to the first active surface of the first semiconductor device. The first back surface of the first semiconductor device and the second back surface of the second semiconductor device are in contact with each other. At least a portion of the first heat conductive layer are in contact with the second heat conductive layer.