Measuring nonuniform web tension for roll-to-roll manufacturing of flexible and printed electronics

Abstract

High-quality roll-to-roll (R2R) manufacturing for flexible and printed electronics often requires uniform web tension. Nonuniformity in web tension can lead to nonuniform performance of printed electronic devices across the width of the web, and excessive nonuniformity in web tension can lead to web wrinkling. Here we develop and test a noncontact resonance (NCR) method and a gentle contact stiffness mapping (GCSM) method for measuring the average web tension and its linear variation across the width of the web. The NCR method uses the lowest symmetric and anti-symmetric frequencies of a web with a closed-form expression to obtain its linearly varied tension. The closed-form expression includes the significant effects of air loading on web vibrations through accurate hydrodynamic functions. While the GCSM method is based on nonlinear regression of the contact stiffness on multiple locations of the web. Both methods are accurate, reliable, and inexpensive, and are compatible for a wide range of web properties, web path, web tension, measurement configurations, and environmental conditions. We cross-validate the two methods on a stationary test stand and in-line test the NCR method in two spans of a moving commercial R2R system. We measure up to 35.58% cross-span tension variation in that system, and both average tension and its linear variation can vary in different spans of the same R2R system. We expect the results presented in this article can improve quality control of R2R processes for flexible and printed electronics and maximize device yields.

Inkjet-Printed Silver Nanowire Ink for Flexible Transparent Conductive Film Applications

“…In recent years, printed electronics (PE) have been considered as an alternative to conventional silicon-based technology due to high manufacturing speed, large-area, low cost, environmental friendliness, and particularly applicable to flexible functional devices [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. PE refers to the electronic product manufacturing technology that functional conductive inks are directly deposited onto substrate to form electronic component or circuit by printed process.…”

“…PE refers to the electronic product manufacturing technology that functional conductive inks are directly deposited onto substrate to form electronic component or circuit by printed process. Common industrial PE process includes screen printing [ 6 ], gravure printing [ 7 ], roll to roll printing [ 8 ], inkjet printing [ 10 ], and so on [ 11 , 12 , 13 , 14 ], and have been applied in some fields such as organic electronics [ 5 , 6 ], flexible electronics [ 2 , 3 , 4 , 11 ], wearable electronics [ 12 ], etc. Among those, inkjet printings particularly attractive in making controllable structure patterned circuits since it offers digital control on the printing process, is easy to integrate into a high throughput, and can be printed for better functional outcome [ 13 , 14 , 15 ].…”

Combustion‐Assisted Photonic Sintering of Printed Liquid Metal Nanoparticle Films

“…[ 10 ] While the speed and electrical performance of CAPS is similar to that demonstrated by a stretching‐based technique, [ 8 ] stretching is incompatible with roll‐to‐roll processing, which typically requires constant web tension. [ 39 ] Similar to other parallel processing techniques like stamping, CAPS can be further scaled to higher speeds using larger or more rapid commercially available IPL sources, thus making this method highly amenable to roll‐to‐roll manufacturing.…”

Model‐Based Optimization of Web Tension Control for the Flexible Cell Stack Assembly of Lithium‐Ion Battery Cells

“…These do not involve a direct measurement of the actual web tension. [ 18 ] They compensate for the changing moments of inertia of the used coils by measuring their diameter and then adjusting the tension through appropriate measures, such as varying the forces of the dancer system or by adjusting the breaking torque on the unwinder. When operating with more sensitive materials, a closed‐loop control system becomes necessary.…”