Aligned Graphite Nanofibers Thermal Interface Material for 3D Chip Stacks
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Solution Overview
Problem
Three-dimensional chip stacks face significant thermal resistance issues due to reduced surface area for heat dissipation, exacerbated by hotspots and temperature gradients, which existing thermal interface materials struggle to address effectively without degrading the base matrix material properties.
Innovation Solution
The method involves aligning graphite nanofibers in a thermal interface material within three-dimensional chip stacks, using a magnetic field to orient the nanofibers parallel and perpendicular to the chip surfaces, enhancing thermal conductivity while maintaining the integrity of the base matrix material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional thermal interface materials with randomly distributed fillers are used, then thermal conductivity can be achieved, but the base matrix material properties (flow, cohesion, interfacial adhesion) are degraded
Solution Approach 1:
The patent uses a composite material system consisting of thermally conductive filler particles (such as aluminum oxide, zinc oxide, or boron nitride) dispersed in an organic matrix material. This composite structure enables the material to simultaneously achieve high thermal conductivity through the filler particles while maintaining the functional properties of the base matrix at reduced loading levels compared to conventional materials.
2Productivity
If three-dimensional chip stacking is implemented, then circuit density per unit area increases, but thermal resistance increases due to reduced surface area and multiple layer interfaces
Solution Approach 1:
The patent applies local quality by positioning thermally conductive pads or layers at specific locations within the chip stack architecture. These localized thermal management structures are placed at critical thermal interfaces (such as between chips and heat sinks, or at intermediate cooling stages) to provide enhanced heat dissipation precisely where needed, rather than uniformly throughout the entire structure.
3Temperature
If high filler loading is used to achieve desired thermal conductivity, then thermal performance improves, but the properties of the base matrix material are degraded
Solution Approach 1:
The patent employs parameter changes by optimizing the loading level of thermally conductive filler particles within a specific range that balances thermal conductivity enhancement with preservation of matrix material properties. Additionally, the filler particle size distribution, shape, and surface treatment are adjusted to achieve maximum thermal performance at moderate loading levels, preventing excessive degradation of flow, cohesion, and adhesion properties.
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 significantly reduces thermal resistance and effectively dissipates heat across the chip stack, maintaining the properties of the base matrix material without requiring changes to microprocessor fabrication processes or adding liquid coolants, thus enhancing cooling efficiency.
Implementation Method 1
aligning graphite nanofibers in a thermal interface material within three-dimensional chip stacks, using a magnetic field to orient the nanofibers parallel and perpendicular to the chip surfaces
Implementation Method 2
enhancing thermal conductivity while maintaining the integrity of the base matrix material
Data Source
AI summary
The chip stack of semiconductor chips with enhanced cooling apparatus includes a first chip with circuitry on a first side and a second chip electrically and mechanically coupled to the first chip by a grid of connectors. The apparatus further includes a thermal interface material pad placed between the first chip and the second chip, wherein the thermal interface material pad includes nanofibers aligned parallel to mating surfaces of the first chip and the second chip and nanofibers aligned perpendicular to mating surfaces of the first chip and the second chip.