Air Bearing Web Handling Enables Scaling Flexible Electronics

Presented by Drew Devitt, New Way Air Bearings

Air Bearing Web Handling Enables Scaling Flexible Electronics When building up electrical devices, photo spacers or other functional surfaces on flexible substrates it can be advantageous or necessary, not to touch the surfaces during processing. This is a problem for the industry as typical web handling is based on converting technology employing driven rollers in contact with the web. Controlling web temperature is done with contact rollers. Vacuum deposition processes require unrolling and rolling up inside a huge vacuum chamber. This just mentions a few of the processes that are typically contact based. Non-contact handling of webs is possible using air bearing technology that can turn, steer, clean, dry, coat and seal microenvironments and vacuum chambers. This enables “pass though” vacuum chambers and mini environments that in turn allow continuous processing rather than batch processing. Non-turning air turns: This can be achieved by using air turns that emit a low flow of high-pressure gas or air though a porous surface that enables a flexible substrate to float over a roller that does not have to turn. Additional advantages can be achieved by squeezing the flexible substrate between two porous air bearing surfaces. When combined with an air turn, by using a complimentary concave radial air bearing, It is possible to use shear forces in the gap to steer the film on the frictionless air turn. This shear force can also be used to spread the film across the air turn creating tension that can avoid wrinkling. Tension of the film between air turns can also be adjusted by using the shear in the air gaps. Interestingly, the problem of web tension and scuffing of the substrate on a spinning roller when rpms and diameters are not perfectly matched with the web seed, is eliminated as there being no contact and no friction on any air turns the web tension is automatically the same though out the length if the line. The power of convective film coefficients in air bearing gaps. This technique of squeezing the substrate between two air bearings Allows for the ability to create high differential pressures. These differential pressures create high velocity (10s of meters per second) gas or air flow though gaps less than a thousandth of an inch thick on both sides of the web. This high pressure, high velocity flow is very effective at boundary layer scrubbing for cleaning, drying and temperature control. Without the substrate captured between two air bearing faces the substrate would beat itself like a flag in the wind. Pass though Vacuum Chambers Controlling the web by squeezing it between two air bearings has important advantages for processes needing vacuum or inert gas environments. Because small air gaps are created by the bearings themselves, and they can operate on the inert gas, they become highly effective non-contact seals for inert environments. When combined with differentially pumped vacuum groves, a web can move from atmosphere to deep molecular flow vacuum, have a deposition process and move back to atmosphere in less than 700mm. In this case the vacuum chambers become 1/100th of the volume in a typical vacuum web coater. This leads to fast pump down times and continuous processing. In summary, Air Bearing Technology offers industry changing advantages for the companies trying to scale printed electronics. But as of this time, the possibilities are little known. This presentation will explain the technical principles, give examples and show videos of hardware performing the functions described.