Laser-Melted Contact Layer for LCD Driver IC Adhesion
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Solution Overview
Problem
Contact defects between the data-driving integrated circuits and the data pattern lines in LCD devices of the COG type lead to increased contact resistance, causing variations in power and data signals, resulting in picture defects such as block dim and gray distortion due to poor adhesion between anisotropic conductive films and contact electrodes.
Innovation Solution
A method of manufacturing LCD devices that involves forming pattern lines and contact electrodes on a substrate, arranging anisotropic conductive films with conductive balls, allowing bumps of driving circuits to connect with these films, and using laser irradiation to melt the pattern lines and electrodes, forming a contact layer that securely connects the conductive balls to the electrodes, thereby reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If anisotropic conductive films are used to connect driving circuits with pattern lines, then the connection is simplified, but contact resistance increases due to poor adhesion
Solution Approach 1:
The contact structure is divided into multiple components: a base contact electrode, an intermediate contact layer formed by laser melting, and conductive balls from the anisotropic conductive film. This segmentation allows each component to perform its specific function optimally, with the contact layer providing strong adhesion between the electrode and conductive balls.
Solution Approach 2:
The physical state of the pattern line and contact electrode is changed from solid to liquid through laser melting, then back to solid upon cooling. This phase change creates a metallurgical bond that significantly improves adhesion strength and reduces contact resistance compared to mechanical contact alone.
2Reliability
If laser irradiation is applied to melt pattern lines and electrodes, then contact resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The traditional mechanical bonding process is replaced with laser-induced melting and metallurgical bonding. The laser provides precise localized heating that melts the pattern line and contact electrode, creating a strong bond without requiring mechanical pressure or complex bonding equipment.
Solution Approach 2:
The laser processing step serves multiple functions simultaneously: it melts the pattern line and contact electrode to create a metallurgical bond, forms a spherical contact layer that improves contact geometry, and creates a robust connection that reduces contact resistance. This multi-functionality reduces the need for separate processing steps.
3Reliability
If contact electrodes are formed to connect with conductive balls, then electrical connection is established, but adhesion strength is insufficient leading to contact defects
Solution Approach 1:
The contact structure uses a composite approach combining the pattern line material, contact electrode material, and conductive ball material. The laser melting process creates a metallurgical bond that integrates these different materials into a unified contact structure with superior adhesion strength and electrical conductivity.
Solution Approach 2:
The contact formation process utilizes phase transition of the pattern line and contact electrode from solid to liquid and back to solid. This phase change enables intimate contact and metallurgical bonding between the electrode and conductive balls, creating a connection with both strong adhesion and low contact resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents contact defects, ensuring stable signal transmission and reducing the occurrence of block dim and noise, thereby improving picture quality by ensuring consistent power and data signal delivery to the LCD device.
Implementation Method 1
irradiating laser light on contact regions to melt the pattern lines and the contact electrodes
Implementation Method 2
melt the pattern lines and the contact electrodes, forming a contact layer
Data Source
AI summary
A display device which can prevent a contact defect of a driver IC and a manufacturing method thereof are disclosed. According to the method, a plurality of pattern lines and a plurality of contact electrodes on a substrate are formed. Each pattern line and each contact electrode are connected each other. Anisotropic conductive films, in which a plurality of conductive balls are included, on the substrate are arranged. A plurality of driving circuits on the substrate and allowing bumps of the driving circuits to be opposite the anisotropic conductive films are arranged. Pressure and heat are applied to the driving circuits such that the bumps of the driving circuits allow the conductive balls to be electrically connected to the contact electrodes. A plurality of contact layers connected with the conductive balls are formed by irradiating laser light on contact regions to melt the pattern lines and the contact electrodes.