Chip on Glass LCD Pad Electrode Embossing
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Solution Overview
Problem
In chip on glass type liquid crystal display devices, the adhesive force between the pad electrode and the flexible printed circuit film is inadequate, leading to non-contact issues, especially in high-temperature high-humidity environments due to step non-uniformity between the pad electrodes and the transparent conductive layers, which hinders the transfer of electric signals.
Innovation Solution
The surface of the pad electrode is embossed to create an embossing pattern, and an anisotropic conductive film with an adhesive is used to connect the external drive circuit, increasing the contact surface area and enhancing the adhesive force, thereby preventing non-contact and ensuring reliable signal transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pad electrode and transparent conductive layer are formed without embossing, then the manufacturing process is simple, but the adhesive force between the pad electrode and flexible printed circuit film is inadequate
Solution Approach 1:
An embossing pattern is formed on the pad electrode surface before forming the transparent conductive layer. This preliminary surface modification creates protrusions that will later enhance adhesive force when the flexible printed circuit film is bonded to the pad electrode.
Solution Approach 2:
The embossing pattern creates a surface structure with protrusions and recesses on the pad electrode. This textured surface increases the effective contact area and mechanical interlocking capability, similar to how porous structures enhance bonding.
2Reliability
If the pad electrode surface is flat, then the manufacturing process is simple, but step non-uniformity causes non-contact issues in high-temperature high-humidity environments
Solution Approach 1:
The embossing pattern is formed on the pad electrode before subsequent layer deposition. This pre-formed surface structure compensates for step non-uniformity that develops during manufacturing, ensuring reliable contact under varying environmental conditions.
Solution Approach 2:
The surface topology of the pad electrode is changed from flat to embossed with protrusions. This parameter change in surface geometry provides mechanical compensation for step non-uniformity, maintaining contact reliability across temperature and humidity variations.
3Strength
If the contact surface area between pad electrode and flexible printed circuit film is small, then the manufacturing process is simple, but adhesive force is insufficient
Solution Approach 1:
The embossing pattern creates a textured surface with increased surface area on the pad electrode. When the flexible printed circuit film is bonded to this embossed surface, the effective contact area is significantly increased, enhancing adhesive force without adding complex assembly steps.
Solution Approach 2:
The pad electrode surface is transformed from a two-dimensional flat plane to a three-dimensional embossed structure with protrusions. This dimensional change increases the contact surface area available for bonding with the flexible printed circuit film.
Data Source
AI summary
A chip on glass type liquid crystal display device and a method for fabricating the same are provided in which a surface of a pad electrode for attaching a flexible printed circuit film is embossed to increase an adhesive force between a pad electrode and a flexible printed circuit film, thereby ensuring contact between the pad electrode and the flexible printed circuit film. Unit pixels in an active region contain thin film transistors formed at intersections of gate lines and data lines. A pad electrode is formed in an inactive region. An embossing pattern is formed on the pad electrode. An adhesive is provided on the pad electrode including the embossing pattern and an external drive circuit part is connected to the pad electrode by the adhesive.