How a Cover Glass Optically Bonded on a PCAP Touchscreen Sensor Glass?

The most ordinary layers for a PCAP touch screen is glass-on-glass structure. That's a cover glass optically bonded on PCAP touchscreen sensor glass. Do you know how the two pieces are optically bonded together?

Top layer of a PCAP touch screen is cover glass, bottom layer is touchscreen sensor glass.  There is a layer of SCA, a kind of optical clear adhesive, between the cover glass and touch sensor glass  that optically bond them to be a PCAP touch screen. The touch sensor glass is to realize the touch function and the cover glass is a protective layer.

As shown in the photos, SCA is hazy. It is first laminated on the touch sensor glass and then laminate the cover glass on it. But touch screen is highly transparent with transmittance upto 86%, how this hazy touch screen to be optically clear? It needs the help of vacuum process. After assembling the cover glass to the PCAP touchscreen sensor with SCA, the touch screen is put on a vaccum machine, usually, at 78°C～82°C under 0.3Mpa ~ 0.5Mpa for 120s ~200s. Under such environment, hazy SCA becomes optically clear. It is one of the SCA's features.

Besides, for GG (glass-on-glass) touchscreens, CloudTop is equiped with two types of vacuum bonding machines. One is for size upto 32 inches, with vacuum bonding platform 0.9m (L) x 0.6m (W) . The other is for those below 75 inches, the platform dimension of which is 2m (L) x 1m (W). Sure the large machines work for small sizes touch screens as well, and grealty enhance the production efficiency. As we can imagine, the small platform can hold 1 piece 32 inch touch screen, and the large platform can hold 4 pieces. 

For any questions or inquiries about touch screens, feel free to contact us to discuss further.