Capacitive Touch Panels Manufacturing Process

The capacitive touch panel is used since 1983. It was etched onto the top watch glass surface. Case in point, Apple put it onto the smartphone that changes our lives totally.

iPhone development, capacitvie touch panel.
iPhone development.
Image source: www.apple.com

Basically, the capacitive touch panel contains three layers and each layer needs substrate glass as a base. After reading this post, you will see what raw materials are necessary and learn about its detailed manufacturing process.

There are three layers in the touch panel.
Image source: https://www.ushio.co.jp/en/

1. Touch sensor production process

1.1 ITO (Indium Tin Oxides) pattern formation stage

Under vacuum conditions use physical or chemical methods to get a film body.

There are 3 main ways to coat a surface: vacuum evaporation, magnetron sputtering, and chemical vapor deposition.

Coating film, ITO, metal coating
Coating film

During the sputtering stage, we can use UV (ultraviolet rays) to clean the film glass substrate. After resisting application, exposure, screen printing, curing, and frame wiring, we get patterns on the substrate glass. Then, we can use the same method to clean and coat the glass.

1.2 Modularization stage

Before this stage, we have to make sure all the components are clean by UV cleaning system.

After that, use OCA (Optical Channel Analyzer) and OCR (Optical Character Recognition) to lamination and coating each layer.

 

Touch panel sensor
Touch panel sensor.
Image source: https://www.ushio.co.jp/en/

Because of the ITO pattern, we can get the touch position direction. The latter controller calculates the ratio of the current drawn and calculates the X-axis and the Y-axis.

The last step for the touch sensor completion is bonding FPC (Flexible Printed Circuit).

FPC, touch panel
Put the FPC on the patterned glass.
Image source: https://www.ushio.co.jp/en/

2. LCD (liquid crystal diode) panel production process

2.1 TFT (Thin Film Transistor) array stage

Just as same as the last stage, we get a piece of substrate glass first and deposition the glass. After that, there is a series of work that has to repeat 5 to 7 times.

touch panel
The series of work that needs to repeat 5 to 7 times.
Image source: https://www.ushio.co.jp/en/

2.2 Color filter stage

Get another piece of substrate glass, clean the surface always have to be the first step.

After that, make the black matrix formation and color the resist application (like coloring the color book).

Then, put the protective film formation onto the glass.

The color resists application process.
Image source: https://www.ushio.co.jp/en/

2.3 Cell stage

Alignment and bonding the TFT layer, you need to make sure the layers are clean. Then, use liquid crystal dripping to alignment the color filter. After that, join these two polarizing plates together.

2.4 Modularization stage

Use COG(cogradient) to join the ACF(Advanced Communications Function) tape. Then, the LCD panel complete.

3. Cover glass production process

The cover glass has to clean and harden by UV(ultraviolet rays). After that, coating by Fluoro. Then, the cover glass is completed.

4. Setup stage

Same as the sensor modularization stage, use OCA lamination and OCR coating to join the touch sensor and LCD panel together. Then, put the cover glass onto the top.

5. Summary

The capacitive touch panel contains three layers.

Each layer is basic on substrate glass. Before and during each process, cleaning is very important. Ideally, the process should under vacuum condition. So the touch panel can be of high quality.

The patterns on the sensor glass set the characteristic of the touch panel. The etching process includes: ITO etching, single surface etching, double surface etch and metal etching.

In addition, the accuracy of the laser printing, Excimer VUV cleaning system, Photo-alignment system, and other process systems can affect the quality.

Some of the processing system.
Image source: https://www.ushio.co.jp/en/

Therefore, the touch panel manufacturing process is very complicated. Instead of lots of manual workers, the process needs to have high function automatic machines and mature pipeline operation.

Although the manufacturing process is very complicated and flexible, we are trying to explain it as simple as we can. One post is hard to contain all the details of the touch panel and a different touch panel has a different process as well.

You are welcome to contact us to get more information. We are glad to talk to you.

Note: We do not own the images used in this post. Feel free to contact us if they belong to you, and we’ll take them down as quickly as we possibly can.

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