Display Pad Wiring Layout for Low-Step Flexible Film Bonding
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Solution Overview
Problem
Display devices face challenges in minimizing the step difference in pad areas where multiple layers are stacked, leading to potential connectivity issues and misalignment during manufacturing, particularly with flexible films and conductive balls.
Innovation Solution
The design incorporates a specific arrangement of pads and wirings, where pads have different portions with varying widths and contact holes, ensuring precise alignment and minimizing step differences by overlapping data lines and connection wirings, and using multiple metal layers to reduce voltage drops and enhance connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers are stacked in the pad area to improve connectivity and reduce voltage drops, then electrical performance is improved, but step difference increases causing misalignment and manufacturing defects
Solution Approach 1:
The patent transitions from a two-dimensional pad structure to a three-dimensional multi-layer stacked structure, adding vertical dimensionality to improve electrical connectivity while managing the associated step difference through careful layer design and thickness control
Solution Approach 2:
The pad structure employs different materials and thicknesses for different layers (e.g., copper layer 1310 with 50-200nm thickness, aluminum layer 1320 with 100-500nm thickness), optimizing local electrical properties while managing the overall step difference to maintain manufacturing precision
2Ease of manufacture
If pad structure is simplified to reduce manufacturing complexity, then ease of manufacture is improved, but connectivity and electrical performance deteriorate
Solution Approach 1:
The pad structure is segmented into multiple functional layers (copper layer 1310, aluminum layer 1320, insulating layer 1330) with distinct roles, allowing each layer to be optimized independently while maintaining overall manufacturing feasibility through standardized fabrication processes
Data Source
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AI summary
A display device includes first and second electrodes, light-emitting elements on the first and second electrodes, data lines extending from a pad area to a display area, connection wirings spaced apart from the data lines and extending from the pad area to a non-display area on respective sides of the display area, first pads overlapping the data lines in the pad area, and second pads overlapping the connection wirings, wherein the connection wirings include a first connection wiring overlapping a second pad, a second connection wiring not overlapping the second pad and overlapping the first connection wiring in the non-display area, and a third connection wiring overlapping the first connection wiring and electrically connected to the second pad, wherein the first and third connection wirings overlap each other in the pad area, and the first, second, and third connection wirings overlap each other in the non-display area.