Transparent Antenna Joint Structure for Fine-Wire IC Bonding
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Solution Overview
Problem
Conductive patterns in transparent antennas with fine wire widths of 5 μm or smaller pose challenges in bonding with IC chips due to reduced bondability, as existing techniques struggle to ensure reliable electrical connection while maintaining transparency and avoiding poor appearance.
Innovation Solution
Adjusting the surface free energy of the conductive patterns and the transparent base material to optimize the bonding process, specifically by creating a joint part with a low surface free energy conductive pattern and a higher surface free energy opening part, allowing for effective wetting and spreading of anisotropic conductive adhesive, thereby improving bondability and reducing adhesive leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the conductive pattern uses fine wire with line width of 5 μm or smaller to improve invisibility, then the transparency and aesthetic appearance are improved, but the bondability with IC chip deteriorates
Solution Approach 1:
The patent applies different surface free energy characteristics to different regions of the conductive pattern. The wire portions are designed with lower surface free energy to prevent adhesive wetting and maintain transparency, while the pad portions have higher surface free energy to ensure good bondability with the IC chip. This local differentiation resolves the contradiction between transparency and bondability by optimizing each region for its specific function.
Solution Approach 2:
The patent changes the surface free energy parameter of the conductive pattern by controlling the ink composition and drying conditions during manufacturing. By adjusting the ink formulation (resin type, solvent ratio) and drying parameters, the surface free energy of different regions is optimized: lower for wire portions to prevent adhesive spread, and higher for pad portions to ensure reliable bonding. This parameter optimization enables fine wire patterns to achieve both transparency and bondability.
2Illumination intensity
If the conductive pattern uses fine wire to improve transparency, then the aesthetic appearance is improved, but the electrical connection reliability with IC chip deteriorates
Solution Approach 1:
The patent creates local quality differences within the conductive pattern by designing pad portions with higher surface free energy than wire portions. The pad areas, which require electrical connection, have surface properties optimized for adhesive bonding, while the wire portions maintain low surface free energy for transparency. This local differentiation ensures that electrical connection reliability is maintained at critical bonding points without compromising overall aesthetic appearance.
Solution Approach 2:
The patent performs preliminary action by pre-forming pad portions with appropriate surface free energy characteristics before the bonding process. During manufacturing, the ink formulation and drying conditions are controlled to create higher surface free energy regions at pad locations in advance, ensuring that when the IC chip is bonded, the electrical connection reliability is already optimized without requiring additional processing steps.
3Illumination intensity
If the surface free energy of the conductive pattern is reduced to improve transparency, then the aesthetic appearance is improved, but the adhesive wetting and spreading capability deteriorates
Solution Approach 1:
The patent applies local quality differentiation by creating regions with different surface free energy characteristics within the conductive pattern. Wire portions have low surface free energy to prevent adhesive wetting and maintain transparency, while pad portions have high surface free energy to ensure proper adhesive wetting and spreading for reliable bonding. This spatial variation in surface properties resolves the contradiction between transparency and adhesive wetting capability.
Solution Approach 2:
The patent changes the surface free energy parameter through controlled ink formulation and drying processes. By adjusting resin types, solvent ratios, and drying conditions, the surface free energy is optimized to be low in wire regions (preventing unwanted adhesive spread) and high in pad regions (ensuring adequate adhesive wetting). This parameter control enables the conductive pattern to achieve both transparency and manufacturability.
4Illumination intensity
If the conductive pattern uses fine wire to improve transparency, then the aesthetic appearance is improved, but the bondability with semiconductor device deteriorates
Solution Approach 1:
The patent implements local quality differentiation by designing pad portions with higher surface free energy than wire portions. The pad areas, which are critical for semiconductor device bonding, have surface properties optimized for adhesion, while the wire portions maintain low surface free energy for transparency. This local optimization ensures that bondability is maintained at critical bonding points without compromising the overall aesthetic appearance of the transparent antenna.
Solution Approach 2:
The patent optimizes the surface free energy parameter through controlled ink formulation and drying conditions during manufacturing. By adjusting the ink composition (resin type, solvent ratio) and drying parameters, the surface free energy is differentiated: lower for wire portions to maintain transparency and higher for pad portions to ensure good bondability with semiconductor devices. This parameter optimization enables fine wire patterns to achieve both aesthetic appearance and ease of manufacture.
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 solution enhances the bondability and reliability of semiconductor devices to the transparent antenna, ensuring stable electrical connections and maintaining transparency, while preventing adhesive leakage and air bubble incorporation, thus improving the overall performance and appearance of the RF tag.
Implementation Method 1
the bonding is performed such that the child antenna pattern of the IC chip label is electrically continuous with a parent antenna pattern formed on a base material
Implementation Method 2
a surface free energy E1 of the first conductive pattern is 60 mJ/m2 or less, and a surface free energy E0 of the transparent base material at the first opening part is larger than the surface free energy E1
Implementation Method 3
an anisotropic conductive adhesive, thereby improving bondability and reducing adhesive leakage
Data Source
AI summary
Provided is a transparent antenna comprising a transparent base material, an antenna part, and a joint part electrically bonded to the antenna part, the antenna part and the joint part being arranged on the transparent base material, wherein the joint part has a first conductive pattern and a first opening part without the first conductive pattern formed thereon, the antenna part has a second conductive pattern and a second opening part without the second conductive pattern formed thereon, surface free energy E1 of the first conductive pattern is 60 mJ/m2 or less, and surface free energy E0 of the transparent base material at the first opening part is larger than the surface free energy E1.