Micro-LED Wafer Bonding Layer for Reliable Chip Mounting
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Solution Overview
Problem
Poor connections between LED chips and circuit boards in micro-LED displays lead to reduced yield rates during mounting, and existing methods like laser bonding fail to address this effectively.
Innovation Solution
An LED wafer and carrier substrate design with a conductive bonding material layer and adhesive layer facilitate precise alignment and secure mounting of LED chips on a circuit board, allowing for efficient transfer and replacement of defective chips without additional bonding material on the circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser bonding is used to mount LED chips on circuit board, then mounting speed is improved, but connection reliability deteriorates due to poor connection between LED chip and circuit board
Solution Approach 1:
The conductive bonding material layer is pre-formed on the LED chip before mounting onto the circuit board. This preliminary preparation ensures that the bonding material is already in position and ready for immediate bonding when the LED chip is mounted, eliminating the need for additional bonding material application steps and ensuring reliable electrical connection from the start
Solution Approach 2:
The conductive bonding material layer acts as an intermediary between the LED chip and the circuit board mounting pad. It facilitates both mechanical bonding and electrical connection, ensuring reliable signal and power transmission while enabling the laser bonding process to achieve both speed and reliability
2Ease of manufacture
If conventional mounting process is used without conductive bonding material layer on LED chip, then manufacturing process is simpler, but yield rate deteriorates due to poor connection
Solution Approach 1:
The conductive bonding material layer is formed on the LED chip during the chip manufacturing process itself, before the chip is mounted on the circuit board. This preliminary formation of bonding material integrates the bonding preparation into the chip fabrication process, maintaining manufacturing simplicity while ensuring high yield rates through reliable connections
Solution Approach 2:
The LED chip is designed to be self-sufficient with the conductive bonding material layer already integrated on its surface. The chip carries its own bonding material needed for mounting, eliminating the need for separate bonding material application steps and ensuring reliable connection without complicating the manufacturing process
3Reliability
If additional bonding material is provided on circuit board, then connection reliability is improved, but device complexity increases
Solution Approach 1:
Instead of placing the conductive bonding material on the circuit board mounting pad as in conventional approaches, the invention inverts the approach by pre-forming the conductive bonding material layer directly on the LED chip surface. This reversal simplifies the overall process as the chip is self-prepared for bonding without requiring additional material application on the circuit board
Solution Approach 2:
The conductive bonding material layer on the LED chip serves as an intermediary that enables direct bonding to the circuit board mounting pad without requiring additional bonding materials or complex multi-layer bonding structures on the circuit board side, maintaining connection reliability while reducing device complexity
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
Enhances yield rates by ensuring reliable connections and enabling easy replacement of defective chips, promoting pixel miniaturization and reducing the need for spare mounting pads.
Implementation Method 1
an adhesive layer between the carrier substrate and the at least one LED chip
Implementation Method 2
a conductive bonding material layer on the terminal electrode
Implementation Method 3
fusing the at least one LED chip to the mounting pad by melting and curing at least a part of the conductive bonding material layer
Implementation Method 4
melting and curing at least a part of the conductive bonding material layer
Data Source
AI summary
An LED wafer includes at least one LED element stack including a first semiconductor layer having a first conductivity type, a light-emitting layer, and a second semiconductor layer having a second conductivity type opposite to the first conductivity type stacked on a crystalline substrate, at least one terminal electrode forming a contact with the first semiconductor layer or the second semiconductor layer, and at least one conductive bonding material layer on the terminal electrode.