Why does the production of touch screens adopt water-based adhesive bonding technology

The editor of HOLS (Suzhou) learned that when producing capacitive touch screens, the main methods used are water-based adhesive or optical adhesive. The display board, touch screen, and protective glass are fully bonded together in the form of seamless steel pipes, which is a very important process flow. According to the type of touch screen, it can be roughly divided into GG, In Cell, On Cell, and OGS. No matter what method is used, it needs to be fitted.

Using OCA optical transparent tape or optical tape without substrate to adhere to the OCA process, in short, using high transparency double-sided tape for adhesion. The adhesive tape material provided by the present invention is mainly composed of acrylic, which has advantages such as high viscosity, high transparency, and good weather resistance, and is most suitable for bonding transparent materials

The OCA process requires secondary bonding, mainly using two methods: mesh and vacuum bonding. The water-based adhesive bonding process uses liquid optical transparent adhesive to bond transparent optical components. The liquid optical transparent adhesive is cured by irradiating it with ultraviolet light with a wavelength of 250-400nm, which is used for bonding capacitive screen

This type of optical adhesive is colorless and transparent, with extremely high light transmittance. It can be cured through visible light, ultraviolet light, medium to high temperature, moisture, etc. Good bonding strength, low curing shrinkage rate, resistant to yellowing, and slightly soft hardnes

The advantages of water-based adhesive bonding technology for capacitive touch screen

According to a large amount of data feedback provided by TP manufacturers, the bonding of touch screens mostly adopts OCA technology, and replacing OCA technology with water-based adhesive bonding technology is the tren

The overall performance of water-based adhesive bonding is better than that of OCA adhesive, but it is not as good as OCA adhesive in terms of overflow and material requirement

The biggest drawback of water-based adhesive bonding is that the bonding process is difficult to effectively control and is not suitable for soft and hard bondin

However, due to the high transmittance and good quality of water-based adhesive bonding, especially for medium to large-sized and high sensitivity capacitive screens, its cost and price are superior to OCA, making the application of liquid water-based adhesive in hard adhesives a trend of industrial developmen

Another important reason for replacing solid OCA patches with liquid optical water-based adhesive bonding is the height of the ink area on the glass cover plat

By splicing two glass substrates, the ink layer area of the upper cover plate occupies a certain height. Therefore, compared with OCA tape, HOLS (Suzhou)  believes that water adhesive bonding can better adapt to the problems of height difference and surface unevenness, thus better solving the problem of bubbles. Many solid OCA laminations use OCA laminations in a vacuum state, which undoubtedly increases costs.