OLED Pad Insulating Layer Fixes Silver Particle Migration
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Solution Overview
Problem
Silver particles precipitated during the manufacturing process of organic light emitting diode displays can move from the pad region to the display area, causing pixel defects due to their higher ionization degree compared to aluminum, leading to image quality issues.
Innovation Solution
Incorporating a second insulating layer between the pads and the first insulating layer in the pad region to cover and fix the silver particles, preventing their movement to the display area, with the second insulating layer being either organic or inorganic and having a thickness of about 1 μm to 3 μm, and a width of the second opening ranging from 5 μm to 15 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver particles are used in the pad region, then electrical conductivity is improved, but silver particles precipitate and move to the display area causing pixel defects
Solution Approach 1:
An insulating layer is introduced as an intermediary between the silver particles in the pad region and the display area. This insulating layer prevents direct contact and migration of silver particles to the display area while maintaining electrical connectivity through the pad structure, thus resolving the contradiction between conductivity and particle migration prevention
2Ease of manufacture
If the pad region is left open without insulating layers, then manufacturing process is simpler, but silver particles move freely causing pixel defects
Solution Approach 1:
The pad region is segmented by introducing an insulating layer that divides the space between the pad and display area. This segmentation isolates the silver particles in the pad region from the display area, preventing particle migration while maintaining a relatively simple manufacturing process by using standard insulating layer deposition techniques
Data Source
AI summary
A display device includes: a substrate including a display area at which an image is displayed with light and a pad region at which the image is not displayed; a plurality of pads through which a signal is applied to the display area, the pads disposed in the pad region; a first insulating layer disposed between adjacent pads among the plurality of pads, in which a first opening is defined which exposes a respective pad among the adjacent pads; a second insulating layer disposed in the first opening of the first insulating layer, in which a second opening is defined which exposes the respective pad exposed by the first opening of the first insulating layer; and silver particles disposed in the first opening, between the first insulating layer and the second insulating layer.