Micro LED Barrier Layer Layout to Prevent Reflow Eutectics
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Solution Overview
Problem
Existing solder bump processes in micro light emitting diode (LED) display devices can lead to eutectic formation between solder bumps and electrode layers during reflow, affecting electrical properties and structural reliability.
Innovation Solution
A micro light emitting diode structure is designed with a barrier layer that has a larger orthogonal projection area than the electrode layer, ensuring the barrier layer covers the electrode layer and prevents eutectic formation during reflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the barrier layer is used to contact the electrode layer, then eutectic formation during reflow is avoided, but the orthogonal projection area of the barrier layer must be larger than that of the electrode layer
Solution Approach 1:
The barrier layer serves as an intermediary between the solder bump and the electrode layer, preventing direct contact and eutectic formation during reflow. By making the barrier layer's orthogonal projection area larger than that of the electrode layer, the design ensures complete coverage and effective isolation, thus improving structural reliability while managing the added structural complexity through deliberate geometric design.
2Reliability
If the barrier layer covers the electrode layer completely, then eutectic formation is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The design establishes the barrier layer's orthogonal projection area to be larger than that of the electrode layer from the outset, during the fabrication process. This preliminary geometric configuration ensures that complete coverage is achieved before subsequent assembly steps, preventing eutectic formation and maintaining electrical properties while setting clear manufacturing specifications for area control.
3Strength
If solder bump is bonded directly to electrode layer, then bonding strength is achieved, but high temperature causes eutectic formation
Solution Approach 1:
The barrier layer acts as a mediator between the solder bump and the electrode layer during the bonding process. It allows the solder bump to bond effectively while preventing direct contact with the electrode layer, thereby maintaining bonding strength while eliminating the harmful eutectic formation that would occur at high temperatures during reflow.
Data Source
AI summary
A micro light emitting diode structure including an epitaxial structure, an electrode layer and a barrier layer is provided. The epitaxial structure has a surface. The electrode layer is disposed on the surface of the epitaxial structure. The barrier layer is disposed on the electrode layer. An orthogonal projection area of the barrier layer on the epitaxial structure is greater than and covers an orthogonal projection area of the electrode layer on the epitaxial structure.