Vacuum-bonding technology for more fragile TFT generation

"The previous TFT generations included extensive mechanics such as metal frames or sheet metal housings that could make good use of an assembly with double-sided adhesive industrial tape or of the necessary dam construction in the traditional bonding methods, such as wet bonding," explained Bernhard Staller, Managing Director, Distec. "The latest TFT generation does not feature these mechanics anymore, and thus neither the tape assembly nor the wet bonding is a mounting option. The current technology trend therefore requires completely new methods such as VacuBond for the assembly of TFT displays with touchscreen and protective glass."

With the vacuum-bonding technology, a touchscreen, protective glass, or a combination of the two, is applied to a TFT display. The assembly is made with the bonding/lamination material Opto-Gel over the complete surface, in pure vacuum and in vertical production direction. A CNC machined tool ensures the precise position of the components according to the product configuration. The process itself is fully automated and carried out in a clean room to avoid dirt inclusions.

The strength of the protective glass is freely selectable and all common touchscreen technologies can be used: resistive analogue, glass/glass, AMR touch or projected capacitive. The Opto-Gel for VacuBond is a specially developed high-performance material and available in 0.3, 0.5, 1 and 1.8mm thickness. Opto-Gel not only connects the individual components, but also contributes to the absorption of strong mechanical influences such as vibration or shock. The VacuBond technology has already proved its worth in the essential drop-ball tests for public terminals, the very strict test runs for railway approval and also easily passed through the certification to IEC 60721-3-7 and MIL-STD 810F.