Vacuum coating aids advances

Bobst Group company General Vacuum Equipment is helping in the development of advanced substrates, a recent installation being a multi chamber PECVD plasma enhanced chemical vapour deposition vacuum roll coater in Asia, for clear barrier coatings.

GVE has developed an improved method of depositing thin layers of predominately inorganic glassy barrier materials with carbon inclusions. This is said to provide a transparent film with high barrier protection against moisture and oxygen, whilst maintaining durability against stretching and bending - an issue which conventional ceramic coatings failed to overcome.

The General CVD vacuum coater features a modular chamber concept that can process web widths up to 2,100mm, with a maximum roll diameter of 1,000mm, running at speeds from 6-600m/min or higher, dependent upon barrier requirements or the number of process modules. Optional equipment can also include plasma pre and post activation, a transmissive web detection system, and various pumping and cryogenic options.

A high accuracy AC vector drive system is said to provide advanced web handling, precise process monitoring and control for superior deposition uniformity and product quality. Its load lock design enables easy loading and unloading of the machine, without breaking the main process vacuum. A fully retracting chamber lid and process source facilitates cleaning and web threading.

“The modular design of the CVD coater allows for varying process requirements, whilst reducing the number of process modules limits the initial capital investment in a fairly new, but rapidly growing market,” explains Nick Copeland, development manager at GVE. “Further modules can be added later to increase production levels when customer demand dictates. An intuitive software interface enables easy interaction with the control system for rapid process configuration, data input and retrieval and process monitoring.”

In addition to the production coater, process trials have been carried out on a 300mm wide CVD pilot machine at GVE's Heywood site.

In another area, the company is to supply two OptiLab roll-to-roll vacuum sputter coaters to Ascent Solar Technologies, of Littleton, Colorado. To be used in the development of advanced photovoltaic (PV) flexible films for solar energy applications, the machines will provide multi-layer deposition of metallic and transparent conducting oxides on plastics film.

AST will use a plastics film coated with thin film PV to transform natural sunlight into electricity. It says the lighter weight solar substrates manufactured will be more flexible and affordable than traditional rigid solar panels. A future CIGS device will be no more than the thickness of a human hair - and made available in rolls, foldable packs or traditional module formats.

Production is set to begin early in 2008 and in the meantime, to help with the process development and transition, prior to delivery of the new coaters later this year, AST will use the OptiLab already installed at the CPI/DuPont Teijin Films facility at Wilton, in the UK.