Thermal Interface Structure for Low-Pressure SoW Heat Removal
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Solution Overview
Problem
Existing system on a wafer (SoW) assemblies face challenges in heat removal due to high pressure requirements for bonding thermal interface materials, which can damage components and reduce reliability, and low-pressure bonding materials like thermal greases may dry out, creating voids and reducing thermal performance.
Innovation Solution
A thermal interface structure comprising a thermal interface layer with vertically aligned graphite or carbon nanotubes and an adhesion layer with horizontally aligned graphite or metal, applied with low pressure to achieve effective heat transfer without damaging the SoW, using a groove structure to house excess thermal grease and maintain contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high pressure is applied to bond thermal interface material, then thermal conductivity is improved, but the electronic component may be damaged and reliability deteriorates
Solution Approach 1:
The thermal interface structure is segmented into multiple functional layers: a compliant layer for pressure distribution, a thermal interface layer for heat conduction, and an adhesion layer for bonding. This segmentation allows each layer to specialize in one function, achieving high thermal conductivity without requiring excessive bonding pressure that would damage the electronic component
Solution Approach 2:
The patent uses a composite structure combining materials with different properties: the compliant layer uses soft, pressure-distributing material; the thermal interface layer uses high thermal conductivity material; and the adhesion layer uses bonding-capable material. This composite approach enables simultaneous achievement of thermal performance and component protection
2Reliability
If low pressure is used for bonding thermal interface material, then component damage is reduced, but thermal performance deteriorates due to material drying out and void formation
Solution Approach 1:
The compliant layer acts as a cushioning element that compensates for potential void formation and material shrinkage over time. This layer maintains continuous contact between the thermal interface layer and heat removing structure, preventing thermal performance degradation even under low bonding pressure conditions
Solution Approach 2:
The compliant layer functions as a flexible element that can deform to maintain thermal contact. This flexibility allows the structure to accommodate thermal expansion, contraction, and settling without creating voids, ensuring sustained thermal performance without requiring high bonding pressure
3Temperature
If thermal interface material is used to bond SoW and heat removing structure, then heat transfer is improved, but bonding strength deteriorates due to insufficient adhesion
Solution Approach 1:
The interface structure is divided into distinct layers with the adhesion layer specifically dedicated to bonding function. This separation of functions allows the thermal interface layer to focus on heat conduction while the adhesion layer provides robust mechanical bonding, solving the trade-off between thermal performance and bonding strength
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 enables low-pressure bonding with high thermal conductivity, reducing the risk of wafer cracking and improving reliability by maintaining efficient heat transfer and minimizing shear stress between the SoW and heat removing structure.
Implementation Method 1
a thermal interface layer and an adhesion layer. The thermal interface layer is positioned between the first side of the electronic component and the heat removing structure
Implementation Method 2
The adhesion layer is positioned between the heat removing structure and the thermal interface layer
Data Source
AI summary
Electronic assemblies such as system on a wafer assemblies are disclosed. The assembly can include an electronic component that has a first side, a heat removing structure that is coupled to the first side of the electronic component, and a thermal interface structure that includes a thermal interface layer and an adhesion layer. The electronic component can be a system on a wafer (SoW). The thermal interface layer is positioned between the first side of the electronic component and the heat dissipation structure. The adhesion layer is positioned between the heat removing structure and the thermal interface layer. With the thermal interface structure, the electronic component and the heat removing structure can be attached together with relatively lower pressure.