Pixel Bonding Pad Layout to Prevent Contact Window Peeling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing process of LED display panels often results in peeling issues at the contact windows of the driving backplate, leading to a decline in yield due to overstress caused by temperature increases during laser bonding.
Innovation Solution
The pixel structure incorporates a specific arrangement of contact windows and conductive patterns, with overlapping windows and strategically placed bonding pads, to reduce stress and prevent peeling during the laser bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser bonding technique is used to join LED elements with bonding pad, then joining efficiency and brightness are improved, but peeling occurs in contact window leading to yield decline
Solution Approach 1:
The bonding pad structure is segmented into multiple layers including a first bonding pad layer, a second bonding pad layer, and a third bonding pad layer. This segmentation distributes the bonding stress across multiple interfaces and layers, preventing concentration of stress at a single contact window interface which causes peeling during laser bonding.
Solution Approach 2:
The bonding pad employs a composite structure with multiple material layers including conductive materials and insulating materials. This composite construction provides both mechanical strength to resist peeling and electrical conductivity for efficient joining, while the layered composite structure absorbs thermal stress during laser bonding process.
2Reliability
If contact window size is increased to improve electrical connection, then conductivity is improved, but stress concentration increases causing peeling
Solution Approach 1:
The bonding pad structure extends into the vertical dimension with multiple stacked layers rather than relying solely on a large horizontal contact window. This dimensional transition allows adequate electrical connection through the stacked conductive layers while maintaining a smaller horizontal footprint that reduces stress concentration at the contact window interface.
Solution Approach 2:
Different regions of the bonding pad structure have different properties optimized for their specific functions. The conductive layers provide electrical connection while the insulating layers provide mechanical support and stress distribution. This local differentiation allows good electrical connection without requiring a large contact window that would concentrate stress.
3Productivity
If laser bonding power is increased to improve joining speed, then productivity is improved, but temperature increase causes overstress and peeling
Solution Approach 1:
The multi-layer composite bonding pad structure with conductive and insulating materials provides thermal management capabilities. The different materials have different thermal conductivities and expansion coefficients that help distribute and manage the thermal stress generated during high-power laser bonding, preventing overstress and peeling while maintaining high joining speed.
Solution Approach 2:
The layered bonding pad structure is designed in advance to cushion against thermal stress. The multiple layers with different material properties act as a pre-configured stress-absorbing structure that protects the contact window interface from peeling during high-power laser bonding, enabling faster joining without causing damage.
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
This arrangement effectively minimizes peeling occurrences, enhancing the yield and reliability of LED display panels by distributing stress more evenly and reducing the impact of temperature-related overstress.
Implementation Method 1
a technique of laser bonding is utilized to join the LED elements with a bonding pad of the driving backplate
Implementation Method 2
laser bonding is utilized to join the LED elements with a bonding pad
Data Source
AI summary
A pixel structure includes a pixel driving circuit, a first insulating layer, a first conductive pattern, a second insulating layer, a second conductive pattern, multiple bonding pads and a light-emitting element. The first conductive pattern is disposed on the first insulating layer and is electrically connected to the pixel driving circuit through a first contact window of the first insulation layer. The second conductive pattern is disposed on the second insulating layer and is electrically connected to the first conductive pattern through a second contact window of the second insulation layer. In a top view of the pixel structure, the first contact window and the second contact window have a first spacing in a first direction, and the first contact window and the second contact window have a second spacing in a second direction.