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Beyond Flexible Circuits

(May 2011) posted on Wed Jun 01, 2011

The standards-development opportunity that exists for printable electronics is in defining the materials and processes for high-performance applications.


By Dave Torp

Printable electronics push the outer limits of flexible material standards. For the past two decades, printed electronics have grown and found commercial applications in markets for radio-frequency identification (RFID), smart labels and displays, sensors, and lighting (OLED). Advancements in conductive printable inks, with a little help from nanotechnology, have overcome some of the early consistency problems in conductive additive materials. Improvements in printing equipment and processes, including the application of flexo-gravure printing, have made high-speed processing of printable electronics a reality. However, variations in materials and processes for printable electronics create many opportunities for improvement.

Several of the largest markets for printable electronics involve being able to process conductive inks on flexible substrates. Adding some further complications—the substrates are often moving at high speed during ink application. The electronics industry and the graphics-arts industry have met at the crossroads of printed electronics.

IPC standards have provided definition and characterization for traditional flexible electronic circuits for many years. IPC-2223, Sectional Design Standard for Flexible Printed Boards, provides insight into the design requirements for flexible circuits. Drilling down further into the flexible-circuit standards is IPC-4202A, Flexible Base Dielectrics for Use in Flexible Printed Circuitry, which defines the flexible bare substrate (dielectric) materials. Some of the big issues with flexible substrates are addressed in IPC-4202A including: inspection criteria, dimensional stability, surface finish, strength, tear resistance, etc.

IPC-6013B, Qualification and Performance Specification for Flexible Printed Boards, provides insights into qualification and performance requirements for flexible printed circuit boards. Some of the requirements given within IPC-6013B can be directly applied to printable electronics as well. Scratches, surface voids, cover films, adhesion requirements, and accuracy requirements are all included in IPC-6013B. Each of the IPC standards for flexible circuits reflects the best practices for design and fabrication using a traditional subtractive process. There are some areas where these standards include additive plating process, as well as adhesive application; however, none of the standards addresses the use of a conductive-ink additive process on which the printable-electronics industry depends.

The printable-electronics market is beginning to mature and experience some of the growing pains that are associated with rapid advancement. For many working in the printable electronic industry, there is a realization that standardization is not too far away. IPC has taken the first steps toward standardization by sponsoring conferences on printable electronics. Although no formal standards development has taken place yet, eventually the materials and processes that reflect best practices within certain segments of the printable-electronics industry will definitely be included in IPC’s future standards-development activities.

Those who have participated on IPC standards-development committees understand the power of standards development. IPC connects thousands of subject-matter experts on a global basis. The amount of knowledge that is shared among users, suppliers, academia, and laboratories within the electronics community is phenomenal. Problems that seem to be insurmountable to one company are within the core competency of another participating company. IPC standards committees are open to all who want to contribute. There is no fee required to participate on IPC standards-development committees. IPC policies require open and balanced participation on standards-development committees. The output of IPC standards-development committees results in some of the best standards in the world for electronics and the electronics-assembly industry.

The standards-development opportunity that exists for printable electronics is in defining the materials and processes for high-performance applications. The uniformity of materials, combined with the process requirements, makes for some great opportunities to develop standards. Development of test methods required to define critical parameters in a reproducible and repeatable way is one of IPC’s core competencies. If you are interested in joining a standards-development group for printable electronics, please contact Dave Torp, vice president standards and technology, at dptorp@ipc.org.

The next conference on flexible circuits sponsored by IPC will be in Minneapolis, MN, June 22-23, 2011. For more information, visit www.ipc.org.

David Torp is the VP of standards and technology for IPC—Association Connecting Electronics Industries, Bannockburn, IL. He has held that position since 2007. Prior to joining IPC, he was a senior staff engineer at Plexus. He also served as VP of marketing and business development at Kester and held various engineering positions at Rockwell Collins as well as Underwriters Laboratories. He has a B.S. degree in Chemical Engineering from Iowa State University.


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