Bonding Pad Structure with Segmented Pins for Thermal Expansion
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Solution Overview
Problem
Conventional bonding methods for display panels fail to effectively align bonding pads due to thermal expansion issues, especially with the transition to ultra-thin flexible substrates, leading to misalignment problems.
Innovation Solution
A bonding pad structure and manufacturing method involving a substrate and flexible printed circuit board with specifically designed pins, including a central bonding pin and symmetric first and second bonding pins, where the pins' widths and spacings are optimized to accommodate thermal expansion, with tilt angles and symmetrical arrangements to improve alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bonding methods are used for display panels, then the bonding process is simple, but thermal expansion causes misalignment of bonding pads
Solution Approach 1:
The bonding pin structure is segmented into multiple components: a first pin on the substrate, a second pin on the flexible printed circuit board, and a connection portion that connects them. This segmentation allows each component to be independently designed and optimized for thermal expansion compensation, improving alignment precision while managing complexity through modular design
Solution Approach 2:
The connection portion of the bonding pin is designed with specific local properties - it has a first end connected to the first pin, a second end connected to the second pin, and intermediate portions with varying cross-sectional areas. This local quality variation allows the connection portion to flex and compensate for thermal expansion differences between the substrate and flexible printed circuit board, maintaining alignment precision under thermal stress
2Length of moving object
If ultra-thin flexible substrates are used to increase screen-to-body ratio, then the display panel becomes thinner and more flexible, but thermal expansion issues worsen causing severe bonding misalignment
Solution Approach 1:
The bonding pin connection portion is designed with variable cross-sectional area parameters along its length. The intermediate portions have different cross-sectional areas that create a gradient structure, allowing controlled flexibility to accommodate thermal expansion. This parameter optimization enables the ultra-thin flexible substrate to maintain bonding alignment precision despite thermal stress during the bonding process
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 optimized pin design reduces misalignment issues by allowing for adjustments based on thermal expansion, enhancing the alignment of bonding pads and improving the screen-to-body ratio of display panels.
Implementation Method 1
bonding pads of display panels cannot be aligned with each other due to thermal expansion of materials of bonding pads
Data Source
AI summary
A bonding pad structure includes a substrate, a flexible printed circuit board, and a plurality of bonding pins. The bonding pins include at least one central bonding pin and at least two first bonding pins. The at least one central bonding pin is located at a center of bonding pins. The at least two first bonding pins are located farthest away from the at least one central bonding pin and have mirror symmetry with respect to the at least one central bonding pin. The at least one central bonding pin includes a first end and a second end. A first width A of the first end and a second width B of the second end satisfy 0<A/B≤1.A tilt angle θ is formed between one of the at least two first bonding pins and one side of the substrate and satisfies 0<θ≤90.