Micro-LED Solder Gradient Layer for Staged Chip Repair
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Solution Overview
Problem
Existing semiconductor device packaging technologies face challenges in accommodating components with varying temperature resistance and soldering requirements, leading to limited usability and reliability issues, especially in micro-LED display devices where fixed soldering temperatures affect solder joint integrity and require secondary repair soldering.
Innovation Solution
A light-emitting device and backplate assembly featuring a solder gradient layer with multiple melting point regions or metal layers, where the melting point decreases in a direction away from the pad, allowing for controlled primary and repair soldering temperatures, enhancing the applicability and reliability of chip soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a solder with a fixed melting point is used, then the soldering process is simple, but the applicability to different components with varying temperature resistance is limited
Solution Approach 1:
The solder is divided into multiple layers with different melting points. The solder structure includes a first solder layer with a first melting point and a second solder layer with a second melting point, where the second melting point is higher than the first. This segmentation allows different components to be soldered at different temperature stages, expanding adaptability to various temperature-resistant components.
Solution Approach 2:
Different regions of the solder structure have different properties. The first solder layer has lower melting point suitable for temperature-sensitive components, while the second solder layer has higher melting point for components requiring stronger bonding. This local differentiation of solder properties enables customized soldering for different component requirements.
2Reliability
If a fixed soldering temperature is used, then the soldering process is straightforward, but secondary repair soldering affects the reliability of already formed solder joints
Solution Approach 1:
The solder structure is segmented into multiple layers with different melting points to enable staged soldering. The first solder layer melts at a lower temperature for initial bonding, while the second solder layer remains solid during primary soldering and only melts at higher temperatures during repair soldering. This segmentation protects the reliability of primary solder joints during repair operations.
Solution Approach 2:
The solder structure is pre-configured with different melting point layers before soldering. The first solder layer is designed to melt first during primary soldering, forming reliable joints, while the second solder layer is designed to melt later during repair soldering. This preliminary arrangement of melting points prevents damage to existing joints during repair.
3Ease of repair
If secondary repair soldering is performed at the same temperature as primary soldering, then repair can be done, but the initial solder joints are melted and reliability is affected
Solution Approach 1:
The solder is segmented into layers with different melting points. The first solder layer has a lower melting point and melts during primary soldering, while the second solder layer has a higher melting point and remains solid during primary soldering. During repair soldering, only the second layer melts, allowing chip removal without damaging the first layer's solder joints, thus maintaining reliability while enabling repair.
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 solder gradient layer enables controlled primary and repair soldering temperatures, avoiding the impact of repair soldering on initial solder joints and improving the yield and applicability of components across different products, facilitating easier detection and removal of defective chips.
Implementation Method 1
a solder gradient layer, disposed on the pad layer of the light-emitting element; and a melting point of the solder gradient layer gradually decreases in a direction facing away from the pad layer
Data Source
AI summary
A light-emitting device used for a display panel includes: a light-emitting element and a solder gradient layer, the light-emitting element includes a light-emitting epitaxial layer and a pad layer formed on the light-emitting epitaxial layer, the solder gradient layer is disposed on the pad layer, and a melting point of the solder gradient layer gradually decreases in a direction facing away from the pad layer. In a process of soldering the light-emitting device to a backplate, because there are multiple melting point regions or metal layers with different melting points in the solder gradient layer, a temperature of primary soldering is controlled to be higher than that of repair soldering in the processes of the primary soldering and the repair soldering, which can avoid an influence of the repair soldering on a solder joint formed during the primary soldering, and effectively control a yield of soldering.