Roll-to-roll (R2R) processing is a manufacturing technique used to form electronic devices on flexible substrate material that is transferred from one roller to on another. A variety of fabrications operations may be performed as the substrate winds its way through multiple rollers. Roll-to-roll processing may also be referred to as web processing or reel-to-reel processing.
A roll-to-roll processing operation typically involves several rollers, called a web, around which the substrate is routed through a number of fabrication operations. These rollers may be oriented so that the substrate is oriented horizontally, vertically, or diagonally as it is transferred from one to the next. On the final roller, sometimes called the take-up roller, the substrate is rolled up rather than being routed on to another roller.
Substrates that are used in R2R processing may be made of a variety of materials depending on the application and processing steps involved in fabrication. Plastic films are desirable for their transparency, flexibility and toughness, but are often susceptible to degradation and dimensional distortion at high temperature. Where transparency is not required, stainless steel foils may be chosen as they tolerate higher temperatures than plastics. Other materials, such as aluminum and copper alloys, may also be used.
Circuit patterns may be formed on the flexible substrate in a variety of ways. Some such production lines employ inkjet technology to deposit material onto the substrate. This process is similar to how an inkjet printer deposits ink onto paper. Some facilities employ photolithography, using light to etch away a pattern on the substrate that may then be filled with another material. Other techniques using ultraviolet light, lasers, and so on, may also be used to imprint the substrate with electrical circuitry.
A variety of other manufacturing steps may also be accomplished using R2R processing. In addition to laying down circuit patterns, such steps as die cutting, laminating, placing labels, cleaning, and more may be performed. Heat sealing and application of a variety of coatings may also be included in a roll-to-roll processing operation.
Benefits of roll-to-roll processing include high production rates and yields. As it allows devices to be fabricated automatically in mass quantities, this technique can help reduce the cost of manufacturing through economy of scale. Although initial capital costs can be high to set up such a system, these costs can often be recovered through the economic advantages during production.
Many products contain electronics fabricated with roll-to-roll processing. These include consumer electronics such as mobile phones and computers, home appliances, and even home exercise equipment. Devices used by the medical industry that incorporate such electronics include handheld blood oxygen monitors, displays for ventilators, and interactive controls for medical imaging devices. Advanced architectural features such as optical shutters that can switch from translucent to transparent are also manufactured with roll-to-roll processing.
Roll-to-roll processing has been particularly influential in the development of thin film solar cell technology. Using a fraction of the material of conventional solar panels, thin film solar cells are making solar power more attractive in the energy market. Processing them on flexible material in a roll-to-roll facility helps bring down their historically high cost. Their thin profile also makes them a more aesthetically appealing option for power generation than bulky conventional panels. As roll-to-roll processing of thin film cells advances, more steps are being automated, leading to price reductions that make this technology more economically competitive.
