Oleophobic technology that supports the future
The oleophobic technology is widely used in various fields, particularly advanced fields such as leading-edge electronic devices. The possibilities of the technology are expanding as technological innovation continues in diverse areas.
This site examines the possibilities of the technology mainly in the fields of electronics and life sciences through case examples.
Case Examples of the Oleophobic Technology
The oleophobic technology is widely used in fields such as leading-edge electronic devices. Fine processing on backplanes has improved in line with advances in processing capacity as well as miniaturization of devices. High durability is required in addition to improved performance. By adding the ability to repel water or oil (oil solutions), or hydrophobic and oleophobic functions, to these devices, fine processing and high durability can be achieved. This section introduces examples of using the technology in leading-edge electronic devices and life sciences.
Usage examples of Oleophobic Photoresists
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What is the oleophobic technology?
The mechanism of repelling liquids
Perhaps the best known example of the oleophobic technology is frying pans that have undergone fluorine processing.
A drop of oil (liquid) dripped onto the surface of such a frying pan forms a ball shape and rolls because of the balance between the surface tension of the frying pan (solid) and the surface tension of the oil (liquid) and the interfacial tension between the oil and the frying pan.
The angle θ between the solid surface and the tangent from the point of contact of the liquid in this state is called wettability (contact angle). This relationship is expressed by Young’s formula (Fig. 1). The wettability (contact angle) changes when the surface (interfacial) tension in each of the terms in the formula changes. For example, the solid becomes less wettable if its surface tension (γS) is reduced, and repels liquids better. That is, oleophobicity involves reducing the surface tension of the solid.
To improve the oleophobicity, materials are often coated with an oleophobic agent, or a base material with a small surface tension is used for the solid itself.
AGC Seimi Chemical Co., Ltd.:
Technologies and Materials of Hydrophobicity and Oleophobicity, CMC Publishing Co., Ltd.:
Fig. 1: Wettability of a liquid on a solid surface
CASE 01Oleophobic Photoresists
The oleophobic technology has been used in the photolithography process for manufacturing OLED display backplanes in recent years, as there were underlying issues in mass producing larger displays. The conventional function of the photoresists used in the photolithography process is to serve as a photosensitive processing material that forms the desired shape. By adding the oleophobic technology, it became possible to mass produce larger OLED displays. This section introduces a case example of using the oleophobic technology in the photolithography process.
CASE 01-1Oleophobicity for manufacturing OLED displays
Issues with larger OLED displays solved by the oleophobic technology
OLED uses organic compounds (inks) as the luminescence materials. There are also RGB pixels of width 10 to 30 μm aligned inside the OLED display panel, as shown in Fig. 2.
The oleophobic photoresist controls the movement of luminescence material during the application of ink and ensures that the luminescence material settles in the precise location within the RGB pixels (see Fig. 3).
In addition, a fluorine compound is used in the oleophobic photoresist. Oleophobicity is expressed only at the top of the bank by using surface transfer toward the interface with air and the orientation characteristic unique to fluorine.
Requirements of photoresists for inkjet OLED display panels
- Contact AngleWater: 100°, xylene: 46°
- Exposure wavelengthsi-line, ih-line, ghi-line
CASE 02Oleophobic coatings
Case examples of using the oleophobic technology in coatings include anti-fingerprint coatings, antifouling coatings, and industrial inkjet nozzles. Depending on the application, such features as hydrophobicity, waterproofing, moisture proofing, acid resistance, and insulation may also be required in addition to oleophobicity.
CASE 02-1Anti-fingerprint coatings
CASE 02-2Oleophobicity in antifouling coatings
CASE 02-3Industrial inkjet nozzles
CASE 03Oleophobicity in microfluidics
Microfluidics is a fluid manipulation technology used for fine processing on channels with flat surfaces, that utilize the base materials such as resin, glass and silicon. The channel surfaces are of nanometer to millimeter order dimensions. Some of the critical application fields of microfluidics include life sciences, chemistry and analysis.
For example, microfluidics is used in biochip devices, for detection of cells, DNA or proteins. Rapid PCR testing is another example of a critical microfluidic application, which have become widely popular during the COVID-19 pandemic. Biochips use the oleophobic technology to dynamically control the droplets of the test sample, etc.
CASE 03-1Oleophobicity in biochips
Examples of fluororesin coating materials used in biochips
This section introduces various fluororesin coatings used on biochips, the performance of the resins, etc.
Comparison of surface contact angle depending on the presence of coating
* Biochips require high hydrophobicity and oleophobicity.
Comparison of critical surface tension of resins
* Biochips require a low critical surface tension.
Comparison of absorption coefficient of resins
|0.01％ or lower||0.01％ or lower||0.5％|
* Biochips require an extremely low water absorption coefficient.
Reasons for Choosing AGC
AGC has used the oleophobic technology in two main areas.
- Introduction of a lineup of standard products equipped with oleophobicity.
- Proposal of customized products for particular purposes in electronic device manufacturing processes, etc.
Customized Products of AGC
We will make proposals according to the purpose of oleophobicity, such as electronic device manufacturing processes and coating on base materials. We have a solid track record in the fields of photoresists, various types of coating, microfluidics, and biochips.
Standard Products of AGC
Our lineup of products with oleophobicity includes:
Customized Products of AGC
AGC manufactures fluororesins from raw materials with excellent repellency.
We discuss with our customers, propose solutions to meet their performance requirements, and connect them to practical applications. We receive inquiries for applications in a wide range of fields, particularly the electronics (including nano-sized applications), life sciences, and automotive(mobility) industries.
Understanding our customers
Sample work pieces
Evaluation and feedback
We suggest the suitable composition of oleophobic photoresist
along with your process.