Pixel Array Substrate Layout for Laser Bonding Alignment
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Solution Overview
Problem
The current manufacturing process of micro-LED display devices faces challenges in accurately aligning and bonding millions of small LED elements with the pixel array substrate due to alignment errors and thermal expansion issues during laser welding.
Innovation Solution
A pixel array substrate is designed with an adjustment structure that includes a first adjustment part with a higher laser absorptance and a second adjustment part with lower absorptance, strategically positioned between the pad group and the pixel driving circuit to enhance thermal energy absorption and distribution during laser welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding process is used to bond LED elements and pads, then bonding strength is improved, but thermal expansion of pixel array substrate occurs causing alignment errors
Solution Approach 1:
The adjustment structure introduces local quality variation by creating regions with different laser absorptance values on the pixel array substrate. The first adjustment part has higher laser absorptance than the second adjustment part, allowing selective thermal energy absorption at specific locations during laser welding. This localized thermal management prevents uniform thermal expansion across the entire substrate, thereby maintaining alignment precision while achieving strong bonding at the LED-pad interface.
2Reliability
If more thermal energy is applied during laser welding, then bonding yield is improved, but thermal expansion increases causing misalignment
Solution Approach 1:
The adjustment structure converts the harmful effect of thermal energy (which causes unwanted thermal expansion and misalignment) into a beneficial effect. By designing the first adjustment part with higher laser absorptance, the structure selectively absorbs thermal energy at controlled locations, generating localized heat that promotes bonding at the LED-pad interface without causing excessive overall thermal expansion. This transforms thermal energy from a harmful factor into a useful tool for enhancing bonding yield.
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 solution improves the bonding yield between the LED elements and the pixel array substrate by accurately managing thermal energy, reducing thermal expansion, and ensuring proper alignment, thereby enhancing the manufacturing efficiency of micro-LED display devices.
Implementation Method 1
An absorptance of the first adjustment part to a laser is higher than an absorptance of the second adjustment part to the laser
Data Source
AI summary
A pixel array substrate includes a pixel driving circuit, a first insulating layer, a pad group, and an adjustment structure. The first insulating layer is disposed on the pixel driving circuit. The pad group is electrically connected to the pixel driving circuit. The adjustment structure is disposed on the first insulating layer and is electrically connected to the pad group. The adjustment structure is located between the pad group and the pixel driving circuit. The adjustment structure includes a first adjustment part and a second adjustment part. At least a part of the first adjustment part overlaps the pad group. The second adjustment part is disposed outside the first adjustment part and is staggered from the pad group. An absorptance of the first adjustment part to a laser is higher than an absorptance of the second adjustment part to the laser.