Liquid Phase Thermal Interface Material in Electronic Packaging
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Solution Overview
Problem
As integrated circuitry scales to smaller feature dimensions and higher packaging densities, the density of power consumption increases, leading to elevated junction temperatures, which can cause damage or performance issues, especially in multi-chip configurations, necessitating effective thermal management solutions.
Innovation Solution
The use of a liquid phase thermal interface material (TIM) sealed in a chamber between the die and an integrated heat spreader, which enhances heat removal by conforming to microscopic surface features and eliminating failure mechanisms like cracking and delamination present in solid phase TIMs, thereby improving thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If solid phase thermal interface material is used, then the device structure is simple, but the thermal conductivity is insufficient and contact resistance is high
Solution Approach 1:
The patent changes the physical state parameter of the thermal interface material from solid to liquid phase. The liquid phase TIM is contained within an encapsulant structure, allowing it to maintain liquid properties for superior thermal conduction while being contained in a structured package. This parameter change resolves the contradiction by achieving high thermal conductivity through liquid phase material while maintaining device structure through encapsulation.
Solution Approach 2:
The patent creates a composite structure combining liquid phase thermal interface material with an encapsulant material. The liquid TIM provides superior thermal conductivity and conformability to microscopic surface features, while the encapsulant provides structural support and containment. This composite approach resolves the contradiction between simple device structure and high thermal conductivity.
2Device complexity
If solid phase thermal interface material is used, then the device structure is simple, but the reliability deteriorates due to cracking and delamination
Solution Approach 1:
The patent changes the physical state from solid to liquid phase, eliminating the brittleness that causes cracking in solid TIMs. The liquid phase material remains flexible and conformable, preventing delamination and cracking issues while maintaining structural integrity through encapsulation.
Solution Approach 2:
The patent uses liquid phase material that can be replenished or replaced if needed, rather than permanent solid TIM layers. The liquid TIM can be re-applied or replaced to restore thermal performance, providing a replaceable solution that improves long-term reliability.
3Reliability
If liquid phase TIM is used, then the thermal conductivity increases, but the device complexity increases due to encapsulation requirements
Solution Approach 1:
The encapsulant serves multiple functions simultaneously: it contains the liquid phase TIM, provides structural support, enables thermal conduction pathways, and protects the liquid material. This multi-functionality reduces the need for separate components, thereby minimizing the increase in device complexity while achieving superior thermal conductivity.
4Reliability
If liquid phase TIM is used, then the contact resistance decreases, but the manufacturing precision requirements increase
Solution Approach 1:
The liquid phase TIM automatically conforms to microscopic surface features and fills gaps between surfaces through its fluid properties. This self-adjusting capability reduces the need for extremely precise surface finishing and alignment during manufacturing, thereby reducing manufacturing precision requirements while achieving low contact resistance.
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 liquid phase TIM increases the rate of heat removal and reduces contact resistance, achieving thermal conductivity up to 10× greater than solid phase TIMs, thus preventing device overheating and reliability failures.
Implementation Method 1
a material comprising a liquid phase thermally conductive material within the chamber
Implementation Method 2
conforming to microscopic surface features and eliminating failure mechanisms like cracking and delamination
Data Source
AI summary
An integrated circuit package that includes a liquid phase thermal interface material (TIM) is described. The package may include any number of die. The liquid phase TIM can be sealed in a chamber between a die and an integrated heat spreader and bounded on the sides by a perimeter layer. The liquid phase TIM can be fixed in place or circulated, depending on application. A thermal conductivity of the liquid phase TIM can be at least 15 Watts/meter-Kelvin, according to some embodiments. A liquid phase TIM eliminates failure mechanisms present in solid phase TIMs, such as cracking due to warpage and uncontained flow out of the module.