Gallium Alloy LED Packaging for Solder Crack Healing and Cooling
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Solution Overview
Problem
Conventional LED devices face issues with solder joint cracking and inefficient thermal dissipation, leading to electrical failure and overheating, which are exacerbated by high temperatures and thermal cycling.
Innovation Solution
Incorporating a liquid metal alloy, such as gallium-based alloys, adjacent to the solder joints and LED chips to heal cracks and enhance thermal dissipation by transferring heat laterally and efficiently through increased surface area contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solder joints are used in LED devices, then electrical connection is established, but cracks form over time due to thermal cycling and elevated temperature operation
Solution Approach 1:
The patent changes the physical state parameter of the solder material from solid to liquid by using a eutectic gallium-indium (EGaIn) alloy with melting point of 15.7°C. This parameter change allows the solder to remain liquid during LED operation, enabling it to flow into and heal cracks that would normally form in solid solder joints under thermal cycling stress
Solution Approach 2:
The patent uses a composite material system combining gallium (68.5 wt%) and indium (10.0 wt%) with trace metals (antimony, bismuth, nickel) to create a eutectic alloy that maintains liquid state at operating temperatures while providing both electrical conductivity and crack-healing capability, overcoming the limitations of conventional solid solder materials
2Temperature
If heat dissipation is directed downward through the LED substrate and PCB, then thermal management is achieved, but thermal dissipation efficiency is limited by the thermal conductivity of air and solid interfaces
Solution Approach 1:
The patent applies a liquid metal alloy (EGaIn) that behaves as a fluid thermal conductor, utilizing its liquid state to improve thermal contact and dissipation. The liquid nature allows it to conform to surface irregularities and maintain intimate contact between the LED chip and heat dissipation path, significantly improving thermal conductivity compared to air gaps or rigid solid interfaces
Solution Approach 2:
The patent changes the thermal conductivity parameter by replacing air (poor conductor) and conventional solid solder (moderate conductor) with a liquid metal alloy that has superior thermal conductivity. The liquid state parameter enables continuous thermal contact while the high thermal conductivity of gallium-based alloy enhances heat transfer efficiency
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 metal alloy effectively heals solder joint cracks at room temperature, improves electrical conductivity, and enhances thermal dissipation, prolonging the LED device's lifespan and reducing wear.
Implementation Method 1
The liquid metal alloy can also be placed adjacent to, and in contact with the LED chip to transfer energy away from the LED chips
Implementation Method 2
when one or more cracks form, the liquid metal alloy can enter the cracks and solidify, healing the cracks
Data Source
AI summary
The present disclosure relates to techniques for providing a liquid metal alloy in a light-emitting diode device that can both heal cracks formed in solder joints on the light-emitting diode (LED) device as well as improve thermal energy dissipation from the LED chips to improve the performance, reduce wear, and prolong the life of the LED chips. In an embodiment, a light-emitting diode device can include a liquid metal alloy containing gallium next to a solder joint, and when one or more cracks form, the liquid metal alloy can enter the cracks and solidify, healing the cracks. The liquid metal alloy can also be placed adjacent to, and in contact with the LED chip to transfer energy away from the LED chips.