Junction Structure for Light Emitting Elements
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Solution Overview
Problem
Conventional bonding structures for light emitting elements and substrates often require high temperatures for bonding, which can lead to stress and instability, especially when using flexible substrates, and do not effectively manage the mixing of bonding metals to achieve a low melting point.
Innovation Solution
A bonding structure that uses a bonding layer containing a first and second bonding metal component, such as Sn and Bi, with NiSn alloy layers and a SnBi eutectic layer, to reduce the melting point and enhance bonding at lower temperatures, while also forming a thin NiSn alloy layer on the substrate to prevent breakage due to stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional solder bonding is used to bond light emitting element and substrate, then bonding strength is achieved, but bonding temperature becomes too high causing stress and instability
Solution Approach 1:
The patent changes the chemical composition parameters of the bonding layer by incorporating multiple bonding metal components (Sn, Bi, Ag, Cu, Zn) in specific proportions. This composition modification enables the bonding layer to achieve adequate bonding strength at lower temperatures, directly resolving the contradiction between bonding strength and bonding temperature.
Solution Approach 2:
The patent creates a composite bonding layer structure consisting of multiple metal components (Sn, Bi, Ag, Cu, Zn) with different properties. This composite material approach allows the bonding layer to exhibit combined characteristics of low melting point (from Bi), good bonding strength (from Sn and Ag), and stress resistance (from Cu and Zn), thereby achieving both adequate bonding strength and lower bonding temperature simultaneously.
2Strength
If high temperature bonding is used, then bonding strength is achieved, but stress and instability increase especially on flexible substrates
Solution Approach 1:
The patent modifies the bonding temperature parameter by using a multi-component metal alloy with lower melting point characteristics. This parameter change reduces thermal stress on flexible substrates during bonding while maintaining adequate bonding strength, thereby improving bonding stability and reducing reliability issues.
Solution Approach 2:
The patent introduces Cu and Zn components specifically to address local stress issues in the bonding layer. These components provide localized stress relief and enhanced ductility, improving the bonding layer's ability to accommodate substrate flexibility without compromising overall bonding strength or stability.
3Temperature
If single metal bonding layer is used, then process is simple, but melting point cannot be sufficiently reduced
Solution Approach 1:
The patent employs a composite material strategy by combining multiple metal components (Sn, Bi, Ag, Cu, Zn) in the bonding layer. This composite approach enables the system to achieve a sufficiently reduced melting point through eutectic interactions between components, while the complexity of composition is managed through defined proportion ranges rather than complex processing steps.
Solution Approach 2:
The patent utilizes phase transition characteristics of multi-component metal alloys, specifically leveraging eutectic melting behavior where the combination of metals creates a lower melting point than individual components. This phase transition property allows the bonding layer to melt and bond at reduced temperatures despite the multi-component composition.
4Temperature
If bonding metals are mixed, then melting point is reduced, but mixing control becomes difficult
Solution Approach 1:
The patent manages metal mixing control by defining specific parameter ranges for each component's proportion in the bonding layer. Rather than requiring precise control of mixing processes, the invention specifies composition ranges (e.g., Bi: 10-40 wt%, Sn: 30-60 wt%) that ensure adequate melting point reduction and bonding performance, simplifying manufacturing precision requirements.
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 bonding structure allows for reliable bonding of light emitting elements to substrates at lower temperatures, reducing stress and improving the structural integrity by controlling the mixing of bonding metals and forming a thin, uniform alloy layer on flexible substrates.
Implementation Method 1
The bonding layer contains a first bonding metal component and a second bonding metal component different from the first bonding metal component... when the bonding layer contains the first bonding metal component and the second bonding metal component different from the first bonding metal component, a melting point at the time of bonding can be reduced
Implementation Method 2
The bonding layer may have an alloy layer, and the alloy layer may be configured of an alloy of a foundation metal component and a bonding metal component of one of the first bonding metal component and the second bonding metal component
Data Source
AI summary
A bonding structure is a bonding structure which bonds a light emitting element and a substrate and includes a first electrode formed on the light emitting element, a second electrode formed on the substrate, and a bonding layer which bonds the first electrode and the second electrode, and the bonding layer contains a first bonding metal component and a second bonding metal component different from the first bonding metal component.