Display Connection Pad Structure for Bonding Defect Reduction
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Solution Overview
Problem
The reliability of organic light-emitting display devices is compromised due to bonding defects that occur during the bonding process of the driving chip to the substrate, which can lead to reduced performance and lifespan of the display device.
Innovation Solution
A display device structure is proposed that includes a connection pad with a multi-layered conductive structure, a cladding layer made of organic material covering the intermediate conductive layer, and a passivation layer made of inorganic material covering the cladding layer. This configuration aims to prevent exposure of aluminum-containing layers and reduce metal ion particles, thereby minimizing bonding defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple bonding process is used to attach the driving chip to the substrate, then the manufacturing process is simple and fast, but bonding defects occur and reliability is reduced
Solution Approach 1:
The connection pad is divided into multiple conductive layers (lower, intermediate, upper) with distinct functions. The lower conductive layer provides electrical connection, the intermediate layer prevents metal ion exposure, and the upper layer facilitates bonding. This segmentation allows each layer to be optimized for its specific function, improving bonding reliability while maintaining manufacturing feasibility.
Solution Approach 2:
The connection pad uses a composite structure combining multiple materials with different properties. The intermediate conductive layer uses a material that prevents metal ion exposure, while the lower and upper layers use materials optimized for electrical conductivity and bonding respectively. This composite approach resolves the contradiction by integrating multiple material advantages into a single structured solution.
2Reliability
If aluminum-containing layers are exposed during bonding, then the bonding process is simple, but metal ion particles are generated and reliability is reduced
Solution Approach 1:
The intermediate conductive layer is formed in advance during the connection pad fabrication process, before the bonding step. This preliminary action of creating a protective barrier layer prevents metal ion exposure during subsequent bonding operations, eliminating the need for additional protective measures and simplifying the overall manufacturing process while improving reliability.
Solution Approach 2:
The intermediate conductive layer acts as an intermediary between the lower conductive layer and the bonding interface. It mediates the bonding process by preventing direct contact between aluminum-containing layers and the bonding environment, thereby preventing metal ion particle generation without complicating the manufacturing process.
3Reliability
If a multi-layered connection pad structure is implemented, then bonding reliability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The thickness and material composition of each conductive layer are carefully controlled within specific parameter ranges. The lower conductive layer has a thickness optimized for electrical connection, the intermediate layer has a thickness sufficient to prevent metal ion exposure, and the upper layer has a thickness optimized for bonding. By controlling these parameters, the multi-layered structure achieves high bonding reliability without requiring excessive manufacturing precision.
Data Source
AI summary
A display device includes: a light-emitting element at a display area; a driving element electrically connected to the light-emitting element; an encapsulation layer covering the light-emitting element; a touch sensor on the encapsulation layer; a connection pad at a bonding area, the connection pad including a lower conductive layer, an intermediate conductive layer on the lower conductive layer, and an upper conductive layer on the intermediate conductive layer; a cladding layer covering at least a side surface of the intermediate conductive layer and including an organic material; a passivation layer covering an upper surface of the cladding layer and including an inorganic material, a portion of the passivation layer being located under the upper conductive layer; and a driving circuit attached to the connection pad.