Flat LED Bonding With Press Plate Re-Alignment for Color Uniformity
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Solution Overview
Problem
The challenge of bonding a large number of light emitting diodes (LEDs) to a circuit board results in uneven upper surfaces, leading to color irregularities in display images due to misaligned emission directions, which are difficult to correct individually.
Innovation Solution
A flat bonding method using a reflow process followed by a press plate to re-bond and align the LEDs, ensuring uniform surface directions and elevations through a stepper movement and inspection for bonding failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large number of light emitting devices are bonded to a circuit board, then the display apparatus can show various images with multiple colors, but the upper surfaces of the light emitting devices become uneven, causing color irregularities
Solution Approach 1:
A solder resist layer is formed on the circuit board before bonding the light emitting devices. This preliminary action creates a controlled bonding surface that prevents excessive solder accumulation and ensures uniform upper surfaces of the bonded LEDs, thereby maintaining surface flatness even when bonding a large number of devices
Solution Approach 2:
A solder resist layer acts as an intermediary between the circuit board and the light emitting devices. This intermediate layer controls the solder flow and bonding process, preventing direct excessive solder accumulation on the LED upper surfaces while ensuring proper electrical connection, thus resolving the conflict between bonding quantity and surface precision
2Ease of manufacture
If the amount of solder used to bond light emitting devices is not precisely controlled, then bonding can be achieved, but the upper surfaces become inclined, causing color irregularities
Solution Approach 1:
The solder resist layer is prepared in advance on the circuit board with specific patterns and thicknesses. This preliminary preparation establishes controlled solder application areas, ensuring that solder is deposited in a controlled manner during bonding, which prevents surface inclination while maintaining ease of bonding
Solution Approach 2:
The solder resist layer's thickness, pattern, and material composition are optimized to control solder flow characteristics. By changing these parameters, the bonding process becomes more robust against solder amount variations, preventing surface inclination even when solder amount is not precisely controlled
3Productivity
If temperature difference occurs at each solder location during bonding, then bonding can be performed, but the upper surfaces of light emitting devices become inclined, causing color irregularities
Solution Approach 1:
The solder resist layer serves as a thermal intermediary that moderates temperature distribution during bonding. It helps equalize temperature differences across various solder locations by controlling heat transfer, thereby preventing surface inclination caused by thermal gradients while maintaining bonding productivity
Solution Approach 2:
The solder resist layer provides a buffer against temperature variations before bonding occurs. By pre-establishing this layer with appropriate thermal properties, the system is cushioned against the harmful effects of temperature differences, preventing surface uniformity issues even when temperature variations occur during the bonding process
4Device complexity
If light emitting devices are bonded without individual repair capability, then manufacturing is simplified, but color irregularities due to inclined surfaces cannot be corrected
Solution Approach 1:
The solder resist layer is designed to prevent surface inclination from occurring in the first place during the bonding process. This preliminary preventive measure eliminates the need for subsequent individual repairs, maintaining simple manufacturing processes while ensuring reliable display quality by preventing defects before they occur
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 achieves uniform alignment of LED surfaces, reducing color irregularities and enhancing display quality by ensuring angular and elevation uniformity among LEDs.
Implementation Method 1
re-bonding at least a portion of the light emitting devices bonded on the circuit board using a press plate while pressing the portion of the light emitting devices
Implementation Method 2
bonding light emitting devices on a circuit board using a reflow process
Implementation Method 3
bonding light emitting devices on a circuit board using a reflow process
Data Source
AI summary
A flat bonding method of light emitting devices including bonding light emitting devices on a circuit board using a reflow process, and re-bonding at least a portion of the light emitting devices bonded on the circuit board using a press plate while pressing the portion of the light emitting devices.