In the major digital products on the news, the screen is often one of the focuses of publicity, with the development of the times, people have become accustomed to high-tech products on the display of splendid luster.

At present, the mainstream display on the market is TFT-LCD, that is, thin film transistor liquid crystal display (Thin Film Transistor-Liquid Crystal Display).

Stock exchange market concept, businesswoman trader looking on laptop and tablet, smartphone with graphs analysis candle line in office room, diagrams on screen.

As we mentioned above, people may not think that filtration is so closely connected to the production of TFT-LCD. Below we will explain the importance of filtration in production for flat panel displays.

The production process of TFT-LCD

TFT-LCD combines microelectronics technology with liquid crystal display technology, and its structure is like a “sandwich”. The TFT array is processed on the glass, and the substrate with color filtering film is used to form a liquid crystal box using LCD technology, and then the polarizer is laminated to form a liquid crystal display.


The TFT-LCD array process is similar to that of semiconductors, except that semiconductors use silicon wafers, while thin-film transistors process glass substrates.

In the manufacture of flat panel displays, the glass substrate is first cleaned, and after the film is formed on the surface, the photoresist is evenly coated on the substrate, and after the processes of exposure, development, etching, and stripping, the graphics on the mask plate are transferred to the substrate to form the exact corresponding graphics.

What are the contaminants in the production process?

 In the TFT-LCD array process, pollutants mainly come from the manufacturing process and the handling, packaging, transportation, and storage of glass substrates, the main pollutants are dust particles, fiber paper dust, mineral oil and grease, and other greases, inorganic particles such as silicon oxide, and residues of the preparation process, water stains, fingerprints, etc.


These contaminants directly affect the quality and economic efficiency of the final product, so the product goes through a complex cleaning process, and after filtration, these cleaning solutions can be discharged or recycled.

Filtration solutions by Brother Filtration

For the different manufacturing stages, Brother Filtration offers accordingly filtration solutions. The followings are filtration solutions in detail.

Cleaning process filtration

Before the production of glass substrates begins, it is necessary to remove foreign substances with physical, chemical, and electrical properties on the surface of the substrate that affects the film formation and the dust, oil, and natural oxides attached to the surface of the substrate to provide a clean film layer and clean texture for subsequent production, in addition to removing the dust and foreign substances on the surface after the film formation.

You can learn more at our industry introduction for part cleaning.

The steps included in the cleaning process and Brother Filtration’s recommended product solutions are shown in the following diagram.


Film-forming process filtration

The film-forming process is mainly divided into two ways, one is sputtering metal film deposition, by charged particles bombarding the surface of the material, so that the atoms get enough energy to enter the gas phase, deposited on the surface of the workpiece, and the use of gas is generally inert gas (such as argon);

the other way is CVD non-metallic film deposition, the use of PECVD technology, a series of chemical reactions to generate solid products and deposited them on the surface of the glass substrate, the use of electronic special gases such as silane, phosphorane, and nitrogen trifluoride.

Whichever method is used involves the supply of gas, the electron gas needs to be filtered to remove any contaminants entrained in the gas delivery before entering the equipment chamber to participate in the reaction. Brother Filtration recommends our Gas filter housing to help you remove the impurities in the gas.

Lithography process filtration

The photolithography process consists of four parts: washing, coating, exposure, and development.

In the lithography process of thin film transistors, each step may introduce harmful particle contamination, microbubble void defects, and metal contamination on the surface of the glass substrate, so the washing process is essential.

lithographyprocess filtration

Coating, exposure, and development are important steps in photolithography. The photoresist is coated on the glass substrate, selectively sensitized by mask plate masking, and then the photoresist sensitized is removed with the development solution to cure the photoresist not sensitized.

The commonly used developing solution is a quaternary ammonium hydroxide (TMAH) solution.

Etching process filtration

The etching process removes the film layer that is not masked by the photoresist, thus obtaining the exact same pattern on the film as on the photoresist. Etching methods are divided into wet etching, which uses the chemical reaction of the solution, and dry etching, which uses gas and plasma technology to etch the material.

In wet etching, the glass substrate is etched in a special tank and then cleaned in a wash tank, and finally dried, the process, as well as the flying damp solution, is as follows.

Dry etching is the use of the reaction gas under the action of high-frequency electric field plasma discharge, plasma and the substrate after the action, the film not masked by photoresist is etched, commonly used gases for sulfur hexafluoride, oxygen, chlorine gas, etc., these gases can also be used to avoid pollution Gist ultra-pure gas filter treatment.

etching process

Stripping process filtration

In flat panel display manufacturing, the residual photoresist needs to be peeled off after the film formation-lithography-etching process, thus bringing the process of this layer of film to an end.

The glass substrate is soaked in the stripping bath, and after the photoresist is softened, the stripping solution is replaced by IPA, then washed in a water wash tank, and finally dried.

stripping process

Relevant Brother Filtration products

With years of filtration experience and advanced manufacturing technology, Brother Filtration is able to provide helpful membrane-pleated filter cartridges and gas filter housing in every TFT-LCD production process.

Membrane pleated PTFE filter cartridge

Polytetrafluoroethylene (PTFE) is used to create the PTFE membrane filters with a pleated filter surface. Brother Filtration manufactures 2 types of PTFE membrane filter cartridges, which are the Deltamax Hydrophobic PTFE cartridge and the Deltamax Hydrophilic PTFE cartridge.

PTFE filter

With suitable flow pathways between media pleats, the pleat technique maximizes the filter’s usable surface area.

These Brother Filtration cartridge filters are made of PTFE and polypropylene support media, both of which are suitable for biological use and chemically inert. Cartridge construction uses thermoplastic sealing methods rather than potentially contaminated adhesives.

Membrane pleated PES filter cartridge

Polyethersulfone Membrane Filter or PES pleated filter cartridge is another type of membrane filter cartridge. It is made from a sulfonated polyethersulfone polymer. Unlike depth cartridge filters, membrane cartridge filters use surface area to block contaminants. Higher retention efficiency can be offered by membrane filter cartridges.

PES filter

One feature of the PES pleated filter cartridge is the asymmetrical pore structure and a higher surface area design (0.75 m2/10-inch length), offering a much higher dirt loading capacity and larger effective filtration area than symmetrical membrane pleated cartridge filters.

Gas filter housing

The biotechnology, food and beverage, and pharmaceutical industries frequently utilize gas filtration. These applications all place a high value on purity. Great standards and high purity are necessary, regardless of sterilization or moisture filtration.

The gas filter housing works with the filter cartridge to purge particles from high-purity gas. Different filter cartridges are used to fit inside the housing depending on the various demands.

gas filter housing

Brother Filtration Gas Filter Housing is made of 304L or 316L stainless steel, which can adopt a quick opening. Its benefits include excellent filtration accuracy, quick filtration times, low adsorption, no media shedding, no leaks, resistance to acid and alkali corrosion, and simple operation.


With the development of digital products, people are longing for more and more high-quality products with better panel displays. Filtration is a crucial part of the production of flat panel displays and helps manufacturers to produce high-quality and more competitive products.

Brother Filtration not only manufactures all kinds of filter products that can be applied in TFT-LCD production but also offers better filtration solutions for panel display manufacturers. If you need more filtration solutions or a better filter cartridge to help your manufacturing, please feel free to contact us directly.

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