Stretching Beyond Flex


Reading time ( words)

Emerging end-use electronic applications are driving dramatic innovations in circuit board and interconnection technology. New form factors, functionality and durability requirements are challenging the status quo for the PCB industry and pushing design, material and process development to the limit. Incipient devices like wearables, epidermal monitors, embedded sensors, smart labels, human machine interfaces (HMIs), conformable antennas, flexible displays and in-mold electronics (IME) require a combination of circuit stretchability and toughness that isn’t achievable with conventional circuit manufacturing technologies.

Device manufacturers are seeking alternative methods for creating wiring patterns and interconnecting components that are more conformable, elastic and durable than currently available. To set the stage for a discussion on stretchable circuit technology, this article describes two classes of polymers commonly used for manufacturing circuit boards and outlines the developmental arc of two fundamental PCB materials, conductive circuits and organic substrates. The article concludes by reviewing stateof-the art, commercially available stretchable substrate and conductor technologies, as well as new materials and processes that are being researched.

Thermoplastic and Thermosetting Polymers

Broadly speaking, the polymers used for manufacturing electronics may be divided into two classes: thermoplastic and thermoset. The division is based on the degree of chemical cross-linking between the constituent molecules and the temperature-related mechanical properties this cross-linking (or lack thereof) imparts. Depending on the resin system, both classes of polymers can exhibit a wide variety of properties. For example, both thermoplastic and thermoset resins can run the gamut of hardness physiognomies from rigid and brittle to flexible and bendable to elastomeric and stretchable.

Thermoplastic polymers typically have a low degree of intermolecular cross-linking. The long chain polymer molecules are tightly “tangled” at temperatures below the glass transition (Tg), resulting in a solid or “glassy” material.

To read the full version of this article which appeared in the March 2017 issue of The PCB Magazine, click here.

Share




Suggested Items

Review: Institute of Circuit Technology 2022 Annual Symposium

06/15/2022 | Pete Starkey, I-Connect007
The British Motor Museum in Warwickshire, housing the world's largest collection of historic British cars, was venue for the 2022 Annual Symposium of the Institute of Circuit Technology on June 8, which attracted a substantial gathering of manufacturers and suppliers from the UK printed circuit industry. ICT chair Emma Hudson reflected upon lessons learned during the pandemic lock-down and how the industry has successfully adapted to circumstances. She commented that the UK’s PCB fabricators are extremely busy, as she introduced an outstanding conference programme including a keynote from the incomparable Happy Holden.

I-Connect007 Editor’s Choice: Five Must-Reads for the Week

05/20/2022 | Andy Shaughnessy, I-Connect007
This week, we bring you an article about manufacturing training for veterans, and a review of a great signal integrity webinar. IPC honors its A-Teams with the coveted Golden Gnome Awards, and Technica discusses various ways for fabricators to increase ROI. Dan Beaulieu has a review of a really cool book: Back to Human—How Great Leaders Create Connection in the Age of Isolation. In spite of all the meetings on Teams and Zoom, it’s easy to feel disconnected. But great leaders find a way to foster that connectivity.

I-Connect007 Editor’s Choice: Five Must-Reads for the Week

05/13/2022 | Nolan Johnson, I-Connect007
The big news in the industry this week was the new bill introduced to the U.S. Congress in support of the PCB manufacturing industry. The Supporting American Printed Circuit Boards Act of 2022, which was introduced by Reps. Anna Eshoo (D-CA) and Blake Moore (R-UT), incentivizes “purchases of domestically produced PCBs as well as industry investments in factories, equipment, workforce training, and research and development.” The bill is a PCB-oriented complement to the semiconductor-oriented CHIPS Act of 2021.



Copyright © 2022 I-Connect007. All rights reserved.