Display Pad Layer Structure for Visible Direct Bump Bonding
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Solution Overview
Problem
Existing display devices face challenges in visually recognizing the contact portion between a pad and a bump, which can lead to difficulties in ensuring proper electrical connection without damaging the display panel, especially during the manufacturing process.
Innovation Solution
A display device design featuring a pad with a first conductive layer, a second layer with patterns arranged in a specific direction, and a third conductive layer, where the second layer includes insulation materials like silicon nitride or conductive materials like molybdenum and copper, and the third layer includes materials like aluminum or titanium, allowing for direct bonding without damaging the panel and making the contact portion visually recognizable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indirect bonding process with high temperature and anisotropic conductive films is used, then electrical connection between pad and bump is achieved, but manufacturing cost increases and panel damage risk remains
Solution Approach 1:
The patent extracts and eliminates the anisotropic conductive film from the bonding process, achieving direct bonding between the pad and bump. This removes the need for expensive special materials while maintaining reliable electrical connection through the exposed conductive pattern on the pad surface.
Solution Approach 2:
The patent changes the bonding parameters by reducing the bonding temperature from high temperature indirect bonding to low temperature direct bonding. The exposed conductive pattern enables effective bonding at lower temperatures, reducing thermal stress on the panel while achieving reliable electrical connection.
2Ease of manufacture
If conventional pad structure is used, then manufacturing is simple, but contact portion between pad and bump is not visually recognizable
Solution Approach 1:
The patent uses the inherent color difference between the exposed conductive pattern (typically dark metallic color) and the surrounding insulation layer (typically light color) to make the contact portion visually recognizable. This color contrast provides clear visual indication of the bonding location without adding special markers or complex structures.
Solution Approach 2:
The pad structure is segmented into distinct functional layers with the conductive pattern exposed at the bonding surface. This segmentation creates a visually distinct contact region that can be easily identified during manufacturing and inspection processes.
3Reliability
If high temperature indirect bonding is used, then electrical connection is achieved, but display panel may be damaged
Solution Approach 1:
The patent changes the bonding temperature parameter from high temperature to low temperature by using direct bonding with exposed conductive patterns. This temperature reduction eliminates thermal stress that could damage the display panel while maintaining effective electrical connection through direct metal-to-metal bonding.
Solution Approach 2:
The patent replaces the thermal field-based indirect bonding process with a mechanical field-based direct bonding process. The exposed conductive pattern enables effective bonding through mechanical contact and pressure without requiring high temperature thermal fields, thus avoiding thermal damage to the panel.
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
The design enables visually recognizable contact between the pad and the bump, ensuring strong bonding and preventing panel damage during electrical connection, while reducing manufacturing costs by eliminating the need for high-temperature indirect bonding processes and anisotropic conductive films.
Implementation Method 1
a second layer disposed on the first layer, the second layer including patterns arranged in a first direction and spaced apart from each other
Implementation Method 2
a first layer disposed on the substrate, the first layer including a conductive material, and a third layer disposed on the second layer, the third layer including a conductive material
Data Source
AI summary
A display device may include a display panel including a pad disposed on a substrate and a driving unit including a bump electrically connected to the pad. The pad may include a first layer disposed on the substrate and including a conductive material, a second layer disposed on the first layer and including patterns arranged in a first direction and spaced apart from each other, and a third layer disposed on the second layer and including a conductive material. The first layer may include portions protruding toward the substrate and respectively corresponding to the patterns.