R2R: First for Flexible
While BIPV and displays require flexibility that can be sold to end users, there is another and more immediate reason for using flexible substrates. Roll-to-roll (R2R) manufacturing processes require it:
• Printing or coating is likely to be used in these processes, and they have been much touted as a way for reducing costs because (at least in theory) less expensive fabrication equipment is used and there is less material wastage. In addition, R2R processing is often associated with room temperature processing.
• Unfortunately, the reality of R2R is often less than encouraging. Much of the enthusiasm for R2R seems to have been dampened over the past five years by less-than-successful R2R projects that have not lived up to expectations. One apparent source of these problems: R2R processes often lead to fabricated devices that have lower performance than equivalent devices that are fabricated using the standard equipment/processes associated with conventional semiconductor ,manufacturing.
Nonetheless, R2R thinking in the fabrication realm is very much alive, in part because it appears to promise the ability to create very low-cost electronics, something that will be essential if a number of technologies are to grow and evolve. Two examples that one might cite here are RFID and OLED lighting, both of which cannot become ubiquitous unless they are offered at a very low price.
However, the reason why R2R is so important in the context of flexible substrates is that it represents a simpler more immediate entry point for a firm interested in selling flexible substrates. All that is required for an R2R process is a flexible substrate and a viable process itself. For an intrinsically flexible substrate, one must add flexible encapsulation and the ability to market the final product, which typically is being sold into a market that does not know about it or know that it wants the product.
Not only does printing present all the economies associated with R2R processing, but since it is a low-temperature process, it means that high-temperature metal foil or polyimide substrates can be shunned in favor of low-temperature plastics (such as PET), reducing substrate costs by perhaps an order of magnitude. In time, this trend would mean opportunities for suppliers of inexpensive plastic films like PET to enter electronics markets in volume, and for electronics manufacturers to recognize a cost advantage by using these materials. Though silicon wafers will likely hold a performance advantage for the foreseeable future, R2R printing could enable a new class of disposable devices for packaging, labels, and similar applications.