Display Device Pad Overlapping Structure for Bonding Reliability
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Solution Overview
Problem
Existing display devices face challenges in maintaining high bonding reliability of pads due to alignment tolerance issues during the bonding process of bumps to pads.
Innovation Solution
The display device incorporates a specific design featuring a first conductive layer with a signal line including a pad contact part and a line part, an insulating layer with contact holes, and a second conductive layer with pad electrodes. This design includes first and second pads with different widths and overlapping patterns to enhance bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alignment tolerance occurs during bump bonding to pads, then bonding reliability deteriorates, but increasing pad size to compensate for alignment issues increases device area
Solution Approach 1:
The patent introduces a third dimension (vertical stacking) by forming pad electrodes in multiple layers (first pad electrode in first conductive layer, second pad electrode in second conductive layer). This multi-layer arrangement increases the effective bonding area without expanding the planar footprint, thereby improving bonding reliability while maintaining compact device area.
Solution Approach 2:
The bonding structure is segmented into multiple independent pad electrodes across different conductive layers. Each pad electrode can be independently positioned and bonded, allowing the system to tolerate alignment variations in individual bonds while maintaining overall connection reliability through the distributed multi-layer architecture.
2Reliability
If pad contact part width is increased to improve bonding reliability, then manufacturing complexity increases due to varying pad dimensions
Solution Approach 1:
The patent applies local quality by making the pad contact part wider than the line part at specific locations where bonding occurs. This localized width increase provides larger bonding targets for bump alignment while maintaining narrower line widths in signal transmission regions, optimizing both reliability and manufacturability without requiring all pads to be uniformly large.
3Reliability
If multiple conductive layers with overlapping patterns are added to enhance bonding reliability, then device complexity increases
Solution Approach 1:
The patent merges multiple functions into the multi-layer conductive structure: signal transmission through line parts, bonding interface provision through pad contact parts, and enhanced bonding reliability through overlapping pad electrodes in different layers. This integration achieves improved bonding reliability while limiting complexity growth by combining multiple functions within a unified multi-layer architecture rather than adding separate systems.
Data Source
AI summary
A display device includes: a first conductive layer including a signal line, which includes a pad contact part and a line part having a smaller width than the pad contact part along a first direction and extending from the pad contact part in a second direction that intersects the first direction, and a first non-contact pattern, which is spaced apart from the pad contact part, on a first side along the first direction; an insulating layer on the first conductive layer and including a contact hole that partially exposes the first conductive layer; and a second conductive layer on the insulating layer and including a first pad electrode, which is electrically connected to the first conductive layer through the contact hole, wherein the first pad electrode overlaps with the pad contact part and the first non-contact pattern.