Low-Temperature Bonding for Reliable LED Performance
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Summary
Problems
Conventional die attach metals, such as the AuSn 80/20 alloy, require high reflow temperatures, which can damage plastic packages used in solid state lighting applications, and are not ideal for thermal conductivity, limiting the reliability and performance of LED devices at higher drive currents.
Innovation solutions
A gold-tin die attach pad with a tin weight percentage of 40% or more is used, allowing for bonding at temperatures less than 250°C and providing enhanced thermal conductivity without damaging plastic packages, while maintaining stability at higher temperatures.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If conventional die attach metals like AuSn 80/20 alloy are used, then good mechanical strength and thermal conductivity are achieved, but high reflow temperatures (305°C) are required which damage plastic packages
Why choose this principle:
The patent changes the compositional parameters of the die attach alloy by increasing the tin content from 20% to 40% or more, which fundamentally alters the melting characteristics and enables low-temperature reflow processing while maintaining adequate thermal conductivity and mechanical properties
Principle concept:
If conventional die attach metals like AuSn 80/20 alloy are used, then good mechanical strength and thermal conductivity are achieved, but high reflow temperatures (305°C) are required which damage plastic packages
Why choose this principle:
The patent employs a composite die attach structure consisting of multiple layers including tin-rich alloy layers, copper layers, and barrier layers, where each layer serves specific functions: tin provides low-temperature bonding, copper provides thermal conductivity, and barrier layers prevent diffusion, collectively resolving the contradiction between low processing temperature and adequate performance
Application Domain
Data Source
AI summary:
A gold-tin die attach pad with a tin weight percentage of 40% or more is used, allowing for bonding at temperatures less than 250°C and providing enhanced thermal conductivity without damaging plastic packages, while maintaining stability at higher temperatures.
Abstract
A light emitting diode chip a support layer having a first face and a second face opposite the first face, a diode region on the first face of the support layer, and a bond pad on the second face of the support layer. The bond pad includes a gold-tin structure having a weight percentage of tin of 50 % or more. The light emitting diode chip may include a plurality of active regions that are connected in electrical series on the light emitting diode chip.