Perforated Foil Sheet Embedded in Thermal Interface Material for 3DIC Heat Dissipation
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Solution Overview
Problem
In Three-Dimensional Integrated Circuits (3DIC), conventional Thermal Interface Materials (TIM) fail to adequately dissipate heat due to insufficient thermal conductivity, limiting the improvement of heat dissipation performance.
Innovation Solution
The use of a Perforated Foil Sheet (PFS) with high thermal conductivity, embedded within the package structure, where the PFS is integrated with TIM layers to enhance heat dissipation by allowing heat to be efficiently conducted from device dies to a lid through its perforations and surrounding areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional Thermal Interface Material (TIM) is used to dissipate heat from device dies, then the package structure is simple and easy to manufacture, but the thermal conductivity is insufficient and heat dissipation performance is limited
Solution Approach 1:
The patent employs a composite thermal management structure consisting of a Perforated Foil Sheet (PFS) with high thermal conductivity embedded within Thermal Interface Material (TIM) layers. The PFS acts as a thermal conduit with through-openings, while the TIM layers provide both thermal conduction and adhesive bonding functions. This composite material approach enables superior heat dissipation performance by combining the high thermal conductivity of the PFS with the adhesive and filling properties of the TIM, effectively resolving the contradiction between heat dissipation performance and structural complexity.
2Reliability
If a Perforated Foil Sheet (PFS) with high thermal conductivity is embedded within TIM layers, then heat dissipation performance is significantly improved, but the package structure becomes more complex
Solution Approach 1:
The patent implements a nested structure where the Perforated Foil Sheet (PFS) is embedded within the Thermal Interface Material (TIM) layers. The PFS is positioned between device dies and a lid, with TIM layers surrounding and filling the through-openings of the PFS. This nesting arrangement allows the high thermal conductivity PFS to serve as a thermal conduit while the TIM layers provide adhesive bonding and fill gaps, achieving reliable heat dissipation without requiring a completely separate complex assembly process.
Solution Approach 2:
The patent merges multiple functions into the integrated PFS-TIM structure: the PFS provides high thermal conductivity pathways, the TIM layers provide adhesive bonding between components, thermal conduction from device dies to lid, and filling of gaps and voids. This merging of thermal management and structural bonding functions into a single integrated assembly reduces the number of separate components and assembly steps, thereby improving reliability while managing the complexity through functional integration.
3Ease of manufacture
If TIM layers are used alone for heat dissipation, then the manufacturing process is simple, but the thermal conductivity is not satisfactory and heat dissipation is bottlenecked
Solution Approach 1:
The patent applies local quality by positioning the high thermal conductivity Perforated Foil Sheet (PFS) specifically at critical heat dissipation pathways between device dies and the lid. The PFS is strategically placed where thermal conduction is most needed, while the Thermal Interface Material (TIM) layers are distributed throughout to provide both thermal conduction and adhesive bonding. This localized enhancement of thermal conductivity at critical interfaces, rather than uniformly throughout the entire package, improves heat dissipation performance while maintaining relative manufacturing simplicity through targeted material placement.
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 integration of PFS with TIM layers significantly improves heat dissipation by leveraging the higher thermal conductivity of the PFS, allowing for more effective heat transfer and management within the 3DIC package.
Implementation Method 1
The material of PFS 20 has a good thermally conductivity, which may be greater than about 20 W/m*K... The thermal conductivity of the PFS, however, is not satisfactory. Hence, the heat dissipation through the TIM becomes a bottle neck
Implementation Method 2
the heat in device dies is dissipated to the overlying heat sink through a Thermal Interface Material (TIM) layer, which adheres the heat sink to the underlying device dies
Data Source
AI summary
A structure includes a thermal interface material, and a Perforated Foil Sheet (PFS) including through-openings therein, with a first portion of the PFS embedded in the thermal interface material. An upper layer of the thermal interface material is overlying the PFS, and a lower layer of thermal interface material is underlying the PFS. The thermal interface material fills through-openings in the PFS.