Display Substrate Bonding Pads for Low-Temperature Pressure-Free Joining
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Solution Overview
Problem
Existing bonding methods for Micro LED and Mini LED in display devices face challenges with low position accuracy, susceptibility to oxidation, and incompatibility with display processes, particularly due to the use of copper pads and high-pressure eutectic welding.
Innovation Solution
A substrate with a protective layer and low-melting-point alloy material is used, where the alloy is deposited in opening regions of the protective layer to bond with pins at low temperatures without pressure, combining the advantages of solder paste and eutectic welding for precise bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copper pads and high-pressure eutectic welding are used for bonding, then bonding strength is improved, but position accuracy deteriorates and oxidation susceptibility increases
Solution Approach 1:
The patent changes the bonding temperature parameter from high-temperature eutectic welding to low-temperature bonding (below 250°C), and changes the pressure parameter from high-pressure to pressure-free bonding. This is achieved by using a low-melting-point alloy material as the bonding combination layer, which melts at low temperature to enable bonding without requiring high pressure, thereby improving position accuracy while maintaining bonding strength
Solution Approach 2:
The patent introduces a low-melting-point alloy material as an intermediary bonding combination layer between the bonding pads and the electronic element pins. This intermediary layer enables bonding at low temperature without pressure, avoiding the oxidation and position accuracy issues associated with direct copper pad eutectic welding while maintaining strong bonding
2Strength
If eutectic welding is used for bonding, then bonding strength is improved, but temperature requirement increases
Solution Approach 1:
The patent fundamentally changes the temperature parameter from high-temperature eutectic welding to low-temperature bonding by selecting a low-melting-point alloy material with melting point below 250°C. This parameter change enables the bonding process to occur at temperatures suitable for display device manufacturing while maintaining strong bonding strength through the eutectic reaction of the alloy material
3Ease of manufacture
If solder paste welding is used for bonding, then ease of manufacture is improved, but position accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-forming the low-melting-point alloy material as the bonding combination layer on the bonding pads before mounting the electronic elements. This preliminary preparation enables precise positioning to be maintained throughout the bonding process, and the low-melting-point material subsequently melts to secure the bonding without requiring high pressure or complex processes
Solution Approach 2:
The patent changes the material parameter from conventional solder paste to low-melting-point alloy material, which enables the bonding process to occur at low temperature without pressure. This parameter change maintains the ease of manufacture advantage while improving position accuracy by eliminating the high-pressure requirement that compromises positioning precision
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 method provides high position accuracy, reduces oxidation, and improves compatibility with display device processes by enabling low-temperature bonding without pressure, enhancing efficiency and reducing damage to electronic elements.
Implementation Method 1
the low-melting-point alloy material is capable of being melted at a first predetermined temperature, to enable the bonding pads and the pins to be bonded to each other
Implementation Method 2
the low-melting-point alloy material is melted to dissociate a metal ion at the first predetermined temperature, the metal ion reacts with the material that the bonding pads are made of, to form a compound, and the metal ion reacts with the material that the pins are made of, to form a compound
Data Source
AI summary
A substrate includes a base substrate, at least two bonding pads are arranged on the base substrate, the base substrate and an electronic element are bonded to each other through the at least two bonding pads, at least two pins are arranged on the electronic element, a protective layer is arranged at a side of the bonding pads away from the base substrate, and an opening region is arranged in the protective layer at each bonding pad, to expose partial surface of the bonding pad. A bonding combination layer made of a low-melting-point alloy material is arranged in the opening region, and the low-melting-point alloy material is capable of being melted at a first predetermined temperature, to enable the bonding pads and the pins to be bonded to each other.