Hybrid TIM Structure for Low 3D Thermal Resistance
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Solution Overview
Problem
Conventional thermal interface materials (TIMs) face instability due to thermal cycling, leading to increased thermal resistance between the IC die and heat spreader/sink, which affects the longevity and power density of IC devices, especially in extreme environments.
Innovation Solution
A hybrid TIM is developed, comprising a high planar thermal conductivity material (e.g., graphitic material) with supplemental material in through-holes, providing enhanced z-dimensional thermal conductivity and compressibility to accommodate non-planarity, thereby achieving low 3D thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a solid TIM preform is used to provide stability and compressibility, then stability and compressibility are improved, but z-dimensional thermal conductivity deteriorates
Solution Approach 1:
The patent applies composite materials by combining a solid TIM preform with high planar thermal conductivity (e.g., graphitic material) and a supplemental material (e.g., metal particles or powder) within through-holes. This composite structure maintains the stability and compressibility of the solid preform while significantly enhancing z-dimensional thermal conductivity through the thermally conductive supplemental material filling the through-holes, thereby resolving the contradiction between stability and thermal conductivity.
2Reliability
If thermal grease is used to provide good thermal conductivity, then thermal conductivity is improved, but stability deteriorates due to fluid flow and drying out
Solution Approach 1:
The patent applies parameter changes by transitioning from a liquid thermal grease to a solid TIM preform with embedded through-holes containing supplemental material. This parameter change from liquid to solid phase maintains good thermal conductivity through the composite structure while dramatically improving stability by eliminating the fluidity and drying issues inherent in thermal greases, thus resolving the contradiction between thermal conductivity and stability.
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 hybrid TIM ensures effective heat transfer both in-plane and out-of-plane, maintaining low thermal contact resistance and accommodating surface irregularities, thus extending IC device lifetimes and enabling higher power densities in extreme environments.
Implementation Method 1
The hybrid TIM ensures effective heat transfer both in-plane and out-of-plane, maintaining low thermal contact resistance
Data Source
AI summary
A hybrid thermal interface material (TIM) suitable for an integrated circuit (IC) die package assembly. The hybrid TIM may include a heat-spreading material having a high planar thermal conductivity, and a supplemental material having a high perpendicular thermal conductivity at least partially filling through-holes within the heat-spreading material. The hybrid TIM may offer a reduced effective spreading and vertical thermal resistance. The heat-spreading material may have high compressibility (low bulk modulus or low hardness), such as a carbon-based (e.g., graphitic) material. The supplemental material may be of a suitable composition for filling the through-hole. The heat-spreading material, once compressed by a force applied through an IC die package assembly, may have a thickness substantially the same as that of the supplemental material such that both materials make contact with the IC die package and a thermal solution.