Multilayer Thermal Conductive Sheet for Leak-Free Liquid Metal TIM
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Solution Overview
Problem
Existing thermal interface materials using liquid metal face issues such as leakage, void formation, and sagging due to phase transition, while multilayer structures increase thermal contact resistance and costs.
Innovation Solution
A multilayer composite thermal conductive sheet comprising a metal foil with transition layers and low-temperature alloy layers, where the transition layers are electroplated or magnetron sputtered to ensure high adhesion, forming a stable structure that prevents leakage and enhances thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid metal is used as thermal interface material, then thermal conductivity is improved, but leakage and sagging occur due to fluidity
Solution Approach 1:
The patent uses a composite structure consisting of a metal foil base layer, a transition layer (indium or tin), and a low-temperature alloy layer. This composite material design allows the low-temperature alloy layer to contain liquid metal with high thermal conductivity while the solid transition and metal foil layers provide structural support and prevent leakage, thus resolving the contradiction between thermal conductivity and leakage prevention.
Solution Approach 2:
The patent changes the melting point parameter of the alloy layer by using low-temperature alloy materials. The low-temperature alloy layer has a melting point lower than the operating temperature, allowing it to be solid during normal operation (preventing leakage) but become liquid when heated (improving thermal conductivity). This parameter change enables the material to dynamically adapt its state based on temperature conditions.
2Object-affected harmful factors
If multilayer structure is adopted to prevent liquid metal leakage, then leakage is reduced, but thermal contact resistance increases
Solution Approach 1:
The transition layer acts as an intermediary between the metal foil base layer and the low-temperature alloy layer. This intermediate layer facilitates strong adhesion between the two layers, ensuring good thermal contact and low thermal contact resistance while maintaining the multilayer structure necessary for leakage prevention. The transition layer mediates the interface between different materials to optimize thermal transfer.
Solution Approach 2:
The patent applies different materials with specific local properties to different layers: the metal foil provides mechanical strength and thermal conductivity, the transition layer provides adhesion and interfacial bonding, and the low-temperature alloy layer provides leakage prevention and thermal interface functionality. This local quality assignment optimizes the overall thermal performance while preventing leakage.
3Object-affected harmful factors
If additional barrier structures are added to prevent liquid metal overflow, then leakage is reduced, but device complexity and cost increase
Solution Approach 1:
The patent merges the barrier function with the thermal interface material itself by integrating the low-temperature alloy layer that contains the liquid metal within a structured composite. Instead of adding separate barrier structures around the liquid metal, the containment function is built into the material layers, eliminating the need for additional foam barriers or containment structures.
Solution Approach 2:
The composite material structure itself serves as the barrier against leakage. The low-temperature alloy layer is contained within the transition layer and metal foil base layer, forming an integrated composite that prevents overflow without requiring external barrier structures. This reduces device complexity while maintaining leakage prevention.
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 sheet achieves thermal conductivity of at least 25 W/m·K with thermal resistance below 0.025 cm²·K/W, preventing leakage and sagging, and maintaining structural integrity.
Implementation Method 1
When the low-temperature alloy layer undergoes phase transition and melts, the transition layers can react with the liquid metal to quickly form an alloy
Implementation Method 2
the transition layer can stably bond the metal foil and the low-temperature alloy layer. This can improve the adhesion between the transition layer and the metal foil, and the adhesion between the transition layer and the low-temperature alloy layer
Implementation Method 3
When the low-temperature alloy layer undergoes phase transition and melts
Data Source
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AI summary
The present disclosure relates to a multilayer composite thermal conductive sheet and its preparation method and application, belonging to the technical field of thermal conductive materials. The sheet includes a metal foil, two transition layers on opposite side surfaces of the metal foil, and two low-temperature alloy layers, with a melting point of 30-300°C, respectively on surfaces of the transition layers away from the metal foil. The metal foil consists of at least one of silver, copper, zinc, and platinum. The transition layer is made of either indium or tin, with a thickness of 5-13 µm. Compounded with a specific metal foil, a transition layer and a low-temperature alloy layer, the sheet has excellent thermal conductivity, with a thermal conductivity greater than 25 W/m·K, and a thermal resistance of less than 0.025 cm2·K/W, while solving the problems such as leakage, sagging, and void formation of liquid metal.