Micro LED-TFT Junction Structure for Oxide-Resistant Metallic Bonding
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Solution Overview
Problem
The presence of an oxide film between micro LED and TFT electrodes prevents metallic bonding, hindering electrical connection in display modules.
Innovation Solution
A junction structure is formed through metallic bonding between micro LED and TFT electrode pads using a solder layer with a capping layer and a filler layer, allowing for the formation of a new metallic compound, enhancing bonding reliability and reducing conformational changes during the transient liquid phase bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transient liquid phase bonding process is used to join electrodes of different thicknesses, then bonding between dissimilar electrodes is achieved, but conformational changes occur during the process
Solution Approach 1:
The electrode pad is divided into multiple layers with different functions: the lower layer performs bonding and the upper layer maintains structural stability. This segmentation allows the bonding interface to accommodate thickness variations through the transient liquid phase process while the upper layer remains stable and prevents unwanted conformational changes.
Solution Approach 2:
Different regions of the electrode pad structure have different properties optimized for their specific functions. The lower electrode pad region is designed for bonding compatibility with varying thicknesses, while the upper electrode pad region maintains structural stability and resists conformational changes, thus achieving both adaptability and stability.
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
This solution enables reliable electrical connection between micro LED and TFT electrodes, improving bonding reliability and reducing heat-affected zones, even for electrodes with different thicknesses or physical properties, thus enhancing the performance of micro LED-based display modules.
Implementation Method 1
a junction structure provided between the at least one LED electrode pad and the TFT electrode pad, the junction structure being formed in a metallically bonded state
Implementation Method 2
A capping layer may be provided at an upper part of the solder layer, and the capping layer may include Au
Implementation Method 3
allowing for the formation of a new metallic compound, enhancing bonding reliability and reducing conformational changes during the transient liquid phase bonding process
Data Source
AI summary
A display module includes a thin film transistor (TFT) substrate including a glass substrate, a TFT layer provided at a front surface of the glass substrate and comprising a TFT electrode pad, and a driving circuit provided at a rear surface of the glass substrate and configured to drive the TFT layer, at least one light-emitting diode (LED) comprising at least one LED electrode pad, and a junction structure provided between the at least one LED electrode pad and the TFT electrode pad. The junction structure is formed in a metallically bonded state.