Indium Thermal Interface Bonding Without High Contact Pressure
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Solution Overview
Problem
Conventional thermal interface materials (TIMs) have limitations in thermal conductivity and require high contact pressures, which can damage sensitive components and are not suitable for high heat flux applications, while also being complex and costly to implement effectively.
Innovation Solution
Indium-based interface structures are formed by positioning a solid indium-based material between two surfaces, heating it above its melting point to liquefy, and then cooling it to create a solid interface that conforms to the surfaces, providing high thermal conductivity without the need for external clamping forces and minimizing damage to adjacent components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal interface materials are used to enhance thermal coupling, then thermal conductivity is improved, but high contact pressures are required which can damage sensitive components
Solution Approach 1:
The patent employs phase transition of indium-based material from solid to liquid state during bonding. The material is heated above its melting point to become liquid, allowing it to flow and conform to surface irregularities, then cooled to solidify, creating a strong thermal interface without requiring high contact pressures.
Solution Approach 2:
The patent changes the physical state parameter of the indium-based material from solid to liquid during the bonding process by controlling temperature. This parameter change enables the material to adapt to surface variations and form intimate thermal contact without mechanical pressure.
2Reliability
If high contact pressures are applied to achieve high thermal conductivity, then thermal performance is improved, but component integrity deteriorates due to damage risk
Solution Approach 1:
The indium-based material undergoes phase transition to liquid state, enabling it to flow and conform to surface irregularities under minimal pressure, then solidifies to create a strong thermal interface that maintains component integrity while achieving high thermal conductivity.
Solution Approach 2:
The patent replaces the mechanical pressure-based bonding system with a thermal-based system. Instead of applying high contact pressures mechanically, the bonding is achieved through controlled heating and cooling that induces phase transition and wetting of the indium-based material to the surfaces.
3Manufacturing precision
If processing temperatures are increased to melt indium-based material, then bonding quality is improved, but adjacent soldered components may suffer from reflow or damage
Solution Approach 1:
The patent carefully controls the temperature parameter during processing, heating the indium-based material to a temperature above its melting point but below the melting point of adjacent solder, typically in the range of 158°C to 182°C, to achieve bonding without causing solder reflow.
Solution Approach 2:
The indium-based material acts as an intermediary that facilitates bonding at temperatures below solder melting points. By selecting indium-based materials with appropriate melting points and using them as the bonding medium, the process enables high-quality bonding while protecting temperature-sensitive soldered components.
4Reliability
If external clamping forces are used to maintain contact between surfaces, then thermal coupling is improved, but device complexity increases
Solution Approach 1:
The indium-based material provides self-service by maintaining its own bonding to the surfaces through its solidified structure. Once the material solidifies after phase transition, it inherently maintains contact with the surfaces without requiring external clamping forces or complex retention mechanisms.
Solution Approach 2:
The patent replaces external mechanical clamping systems with an intrinsic material-based bonding mechanism. The solidified indium-based material itself provides the bonding force and maintains thermal coupling without needing external clamps, screws, or other mechanical retention devices.
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 indium-based interface structures offer enhanced thermal conductance, reduced component operating temperatures, and improved cooling performance compared to conventional TIMs, while being simpler, lighter, and less costly to implement, with minimal risk of damage to delicate components.
Implementation Method 1
heating the indium-based material above its melting point while in contact with each of the two surfaces to cause the indium-based material to reflow or otherwise liquefy between the two surfaces
Implementation Method 2
The indium-based material may then be cooled below its melting point to form a solid interface material structure that is positioned between and in contact with each of the surfaces
Implementation Method 3
indium-based interface materials may be selected to have a melting point above anticipated operating temperature of the completed assembly or device... that have a thermal conductivity greater than conventional TIMs
Data Source
AI summary
Indium-based interface systems, structures, and methods for forming the same are provided. The disclosed indium-based interfaces may be formed as solid structures between two solid surfaces by providing a solid indium-based material between the two surfaces, and heating the indium-based material above its melting point while in contact with each of the two surfaces to cause the indium-based material to reflow or otherwise liquefy between the two surfaces. The indium-based material may then be cooled below its melting point to form a solid interface material structure that is positioned between and in contact with each of the surfaces.