In-Situ Alloy Thermal Interface Material for Easy Placement and Liquid Cooling
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Solution Overview
Problem
Current thermal interface materials (TIMs), particularly liquid metals, pose challenges in placement on printed circuit boards due to their liquid form, requiring specialized equipment, whereas solid metals can be easily handled with traditional methods, but they do not maintain a liquid state after device deactivation, leading to inefficient heat transfer.
Innovation Solution
A method involving multiple solid metal TIMs with different solidus temperatures, where the assembly is heated to form a liquid alloy with a lower solidus temperature than the individual metals, allowing for efficient heat transfer and maintaining a liquid state even after device deactivation, using metals like gallium, indium, and tin to create a multi-element alloy with improved thermal properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid metals are used as TIMs to achieve high thermal conductivity and low thermal surface resistivity, then thermal transfer efficiency is improved, but placement difficulty increases requiring specialized equipment
Solution Approach 1:
The patent changes the physical state parameter of the TIM from liquid to solid during placement, then to liquid during operation. Solid TIMs can be handled with traditional pick-and-place equipment, while liquid TIMs provide superior thermal conductivity. This parameter transformation resolves the contradiction between ease of placement and thermal performance.
Solution Approach 2:
The patent employs a dynamic state change mechanism where the TIM transitions from solid to liquid based on operating temperature. The solidus temperature is engineered to be below the operating temperature range, allowing the TIM to be placed in solid form and automatically transform to liquid form during device operation, achieving both easy placement and high thermal efficiency.
2Ease of operation
If solid metals are used as TIMs to enable traditional placement methods, then placement ease is improved, but thermal conductivity decreases due to solid state
Solution Approach 1:
The patent utilizes phase transition from solid to liquid state during device operation. The TIM is placed in solid form for ease of handling, then transitions to liquid form when the device operates above the solidus temperature, achieving high thermal conductivity. This phase transition resolves the contradiction between placement ease and thermal performance.
3Device complexity
If a single solid metal TIM is used, then placement simplicity is improved, but the TIM solidifies after device deactivation reducing thermal efficiency
Solution Approach 1:
The patent uses composite material composition with multiple metals having different solidus temperatures. This composite TIM maintains liquid state at lower temperatures while still being placeable in solid form, ensuring continuous liquid state and sustained thermal conductivity even after device deactivation, resolving the contradiction between composition simplicity and thermal performance continuity.
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
Enables efficient heat transfer by forming a liquid alloy with a lower solidus temperature than the individual metals, allowing the TIM to remain in a liquid state after device deactivation, thus improving thermal conductivity and reducing thermal surface resistivity.
Implementation Method 1
forming a liquid TIM alloy from the solid metal TIMs by heating the assembly above a first solidus temperature of the first solid metal TIM
Implementation Method 2
the first solid metal TIM becomes a first liquid metal TIM when the assembly is heated above the first solidus temperature; and forming the liquid TIM alloy comprises dissolving the second solid metal TIM in the first liquid metal TIM
Data Source
AI summary
Thermal interface materials deposited in solid form, in a layered manner, and their uses in electronics assembly are described. In one implementation, a method includes: forming an assembly including multiple solid metal thermal interface materials (TIMs) between a first device and a second device such that a first surface of the solid metal TIMs is in touching relation with a surface of the first device, and a second surface of the solid metal TIMs opposite the first surface is in touching relation with a surface of the second device, the solid metal TIMs including a first solid metal TIM and a second solid metal TIM; and forming a liquid TIM alloy from the solid metal TIMs by heating the assembly above a first solidus temperature of the first solid metal TIM, the liquid TIM alloy having a second solidus temperature below the first solidus temperature.