Flexible and Stretchable Hybrid Electronics Manufacturing for Wearables: Challenges and Solutions

What do you get when you put two really tech-savvy guys on a stage together to talk about the highest priority issues in manufacturing flexible hybrid electronics? You get a deep appreciation for the complexity of the challenges, and the breadth of opportunities that lay ahead.

Dr. Anwar Mohammed, Senior Director of the Advanced Engineering Group at Flex, and Jason Marsh, Director of Technology for NextFlex, shared the stage recently to bring this story to light at the 2017 FLEX conference in Monterey, California

Dr. Mohammed opened the talk crediting the creative and smart Flex customers who put forward their most challenging problems that led to the “Sketch to Scale” system that enables customer vision to become a reality. Those customer successes have led to more than 40 patents and nearly $2B in annual wearable revenues for the company. He also said that collaborative organizations such as the SEMI FlexTech Alliance and NextFlex stimulate growth of the FHE manufacturing ecosystem, and are essential for the success of the diverse set of companies participating in FHE now and in the future.

Dr. Mohammed outlined how the “Sketch” process kicks off the wearables development process for Flex projects, as follows:

• Design – sketch, mechanical, materials selection, DFX/FMEA
• Modeling – thermal simulation, material simulation, FMEA/DFX
• Prototyping – project initiation, DOE, and process development
• Evaluation – failure analysis, reliability testing, and functional validation, and finally
• Optimization – design rules/guidelines, process optimization, and design improvement

This closed-loop process ensures continuous learning and product improvement, but he noted that there are still many challenges ahead in bringing new wearable technology to volume-scale manufacturability.

According to Dr. Mohammed, there is currently great interest in fabric wearables, and through collaborative engagement, Flex is keeping one step ahead of customer demand. Printed copper on cotton, first printed on TPU fabric, and then laminated onto the fabric, is one example of where ongoing collaboration is needed in order to perfect the process. He emphasized that while models are still needed for reliability and testing across the FHE spectrum, the collaborative environment works well, especially where FHE processes are being adapted from semiconductor or electronics manufacturing where examples of collaboration have served those industries well for many years.

Dr. Mohammed concluded his remarks with a wish list for the supply chain community that will enable Flex to continue to deliver on customer demands, including:

1. Materials technology (stretchable conductive inks, low temperature solders)
2. Deposition printing (printing on curved surfaces 2.5D 3D surfaces and R2R printing)
3. Water Ingress (water resistant coatings, mechanical protections)
4. Standards (for reliability, stretchability, bending, etc. for design, modeling and simulation, design guidelines)
5. Printable battery with high MRL (print on cloth, stretchable substrates)
6.  Special assembly processes like ACF Bonding
7.  Integrating ICs into textiles (flexible chips)

Finally, Dr. Mohammed said that he was hopeful that the right people and companies were, in fact, in attendance at the conference so that progress could be made on many of these fronts, and he invited the community to get engaged with collaboration platforms focused on the highest priority areas for wearables.

The discussion then transitioned, and Jason described how the FHE community is rising to the challenge and solving some of these problems. He provided background on NextFlex, America’s Flexible Hybrid Electronics Manufacturing Institute, which is a leading force in the Manufacturing USA network of Institutes. Formed through a cooperative agreement between the US Department of Defense and FlexTech Alliance, NextFlex is a consortium of companies, academic institutions, non-profits and state, local and federal governments with a shared goal of advancing U.S. manufacturing of FHE. Since its formation in 2015, NextFlex’s elite team of thought leaders, educators, problem solvers, and manufacturers have come together to collectively facilitate innovation, narrow the manufacturing workforce gap, and promote sustainable manufacturing ecosystems.

1. During Marsh’s presentation he emphasized that NextFlex is here to:
2. De-risk FHE innovation through use of pilot line equipment and processes;
3. Enable teamwork and collaboration;
4. Support cost-shared projects, fostering connection between companies, academia, and government partners, and solving key challenges for commercial interests;4. Collectively problem-solve;
5. Shorten timelines for new technology adoption, and
6. Support a talent pipeline for manufacturing ecosystem growth.

He then shared progress on several of the cost-share projects now underway and the benefits of not only technology advancement, but also the betterment of the FHE community at large. Those benefits include project updates being shared in real-time with all NextFlex members in an effort to increase the pace of learning and adoption of knowledge into the mainstream.

To the point made earlier by Dr. Mohammed, Marsh highlighted a series of projects tackling the area of reliability testing and standards features-work being done by Georgia Tech, University of Massachusetts Lowell, Auburn University, Raytheon, Optomec, GE, Boeing, Binghamton Univerisity, DuPont, Jabil, and others as proving to advance the FHE field overall. He described this team’s work as developing a common language and common approach for identifying and removing roadblocks, including test pattern files and prints, FHE Process Design Kit (PDK), cost models, and a materials and process database. And, he emphasized that all are being developed in a pre-competitive members-only environment.

Jason closed his portion of the talk by inviting the community to bring the FHE industry’s greatest challenges to NextFlex, stating that the collaborative framework is primed and ready to propel the industry forward.

For more information about Flex, visit www.flex.com, and for more information about NextFlex, visit www.nextflex.us.