LED Display Panel Electrode Joining Without Circuit Board Laser Limits
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Solution Overview
Problem
Conventional methods for manufacturing LED display panels are limited by the need for laser beams with wavelengths transmittable through circuit boards, restricting the design flexibility of circuit boards due to the inability to place metal interconnects with high absorption rates in the laser beam's path.
Innovation Solution
A method involving an LED wafer holding step, circuit board holding step, positioning step, electrode joining step using a laser beam absorbable by the circuit board, buffer layer breaking step using a pulsed laser beam, and a peeling step to increase design freedom by allowing metal interconnects with high absorption rates to be placed on the circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laser beam with wavelength transmittable through the circuit board is used in the electrode joining step, then the laser beam can pass through the circuit board to join electrodes, but metal interconnects with high absorption rates cannot be placed in the laser beam path, reducing design freedom
Solution Approach 1:
The patent inverts the conventional approach by applying the laser beam from the reverse side of the circuit board rather than through it. This allows the use of laser wavelengths that are absorbed by metal interconnects (such as copper interconnects absorbing infrared laser), enabling metal interconnects to be placed anywhere on the circuit board without restricting laser beam paths. The laser beam heats the electrode and interconnect materials from below, achieving reliable electrode joining while maintaining full design freedom for circuit board layout.
2Adaptability or versatility
If metal interconnects with high laser absorption rates are placed on the circuit board, then design freedom is increased, but the laser beam cannot pass through the circuit board to join electrodes effectively
Solution Approach 1:
The patent reverses the laser beam application direction to illuminate from the reverse side of the circuit board. This inversion allows laser wavelengths that are strongly absorbed by metal interconnects to be used, since the laser beam does not need to pass through the metal interconnects on the front side. Instead, the laser beam heats the electrode and interconnect materials from below, achieving both high design freedom and reliable electrode joining.
3Ease of manufacture
If a conventional laser beam application method is used, then the process is simple, but the buffer layer cannot be broken effectively to separate LEDs from the substrate
Solution Approach 1:
The patent employs periodic pulsed laser action to break the buffer layer. By applying laser beams in periodic pulses rather than continuous illumination, the method achieves precise control over buffer layer breaking. The pulsed laser delivers concentrated energy bursts that effectively fracture the buffer layer along element separating lines, enabling clean separation of LEDs from the substrate while maintaining process simplicity through automated pulse control.
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 method enhances the degree of freedom in designing circuit boards by enabling the use of metal interconnects with high absorption rates, while maintaining effective electrical connections and separation of LEDs from the substrate.
Implementation Method 1
applying a laser beam having a wavelength absorbable by a reverse side of one of the circuit board and the LED wafer, to the reverse side of the one of the circuit board and the LED wafer, thereby heating at least either the electrode layer of the LED wafer or the electrode of the circuit board
Implementation Method 2
laser beam having a wavelength absorbable by a reverse side of one of the circuit board and the LED wafer
Implementation Method 3
breaking the buffer layer by applying a pulsed laser beam having a wavelength transmittable through the substrate of the LED wafer, to the buffer layer through a reverse side of the LED wafer
Implementation Method 4
After the electrodes on the circuit board have temporarily been melted by the applied laser beam, they are solidified, whereupon the electrodes on the circuit board and the electrode layers of the LEDs are electrically connected to each other
Data Source
AI summary
A method of manufacturing an LED display panel includes holding an LED wafer on a first holding unit, holding a circuit board on a second holding unit, positioning electrodes of the board at positions corresponding to electrode layers of the wafer while a face side of the board and a face side of the wafer are facing each other, joining the electrode layers and the electrodes to each other by applying a laser beam having a wavelength absorbable by a reverse side of one of the board and the wafer, to the reverse side of the one of the board and the wafer, thereby heating at least either the electrode layers or the electrodes, and breaking the buffer layers by applying a pulsed laser beam having a wavelength transmittable through a substrate of the wafer, to the buffer layers through a reverse side of the wafer.