By Gity Samadi, Ph.D., senior dir.-R&D Programs, SEMI FlexTech
SEMI FlexTech has been advancing the state of the art in flexible, hybrid and printed electronics (FHE) for more than 22 years. FHE technology promises to bring electronics out of their boxes and enable low-power, low-weight and more environmentally friendly electronics products. Its activities range from R&D funding projects, research-team building and standards setting to educational activities such as gap analysis workshops, executive events and technical conferences.
SEMI FlexTech Funded Projects
SEMI FlexTech funds technology-development R&D projects in technology readiness levels (TRLs) 2-5 area. Its funding, in partnership with the US Army Research Laboratory (ARL), is focused on technologies advancing the state of the art in both commercial and defense sectors. An example of typical topical areas include:
· Advanced materials for encapsulation, printing and conductors
· Electronics environmental sustainability for FHE
· Heterogeneous packaging for FHE
· FHE power and power integration
· Reliability as it applies to FHE
· Environmental-sustainability aspects related to FHE.
SEMI FlexTech relies on teams of members and other industry experts to identify the technical gaps and evaluate project proposals to fill those gaps.
Environmentally sustainable electronics with FHE
Products built with FHE components often are more environmentally friendly than rigid, boxed electronics products. FHE products reduce the electronics wastestream with more organic components, and they are manufactured in a way that creates less waste or uses fewer chemicals that contribute to greenhouse-gas emissions. For example, using carbon inks vs. less organic mixtures.
Flexible electronics, with their smaller packaging, organic earth-friendly components and lower power requirements, allow for less-caustic battery technology. This search for novel materials has included the development of graphene, which has led to its use in less-caustic and carbon-intensive, yet stronger and smaller, cement mixtures for large and small building projects.
FLEX 2023 takeaways
The 2023 FLEX Conference, held this past summer in San Francisco, CA, alongside SEMICON WEST, provided numerous examples of continued developments in flexible, printed and flexible-hybrid electronics technologies applied to sensing, robotics, communications and other applications. At the same time, there is growing focus on applying various additive-manufacturing equipment, materials and processes to solving the challenges of heterogenous integration and other forms of advanced packaging adopted by the semiconductor industry. The following are key takeaways from the conference.
New developments in printing: A variety of printing techniques have been developed for or adapted to the creation of electronics functionality (conductors, resistors, capacitors, antennae, etc.) on flexible substrates or integrated onto 3D structures. Two new approaches presented at FLEX 2023 demonstrated the potential for high-volume manufacturing.
Komori America (Rolling Meadows, IL) described the company’s new approach to improving productivity and yield in traditional screen printing with its gapless roll-to-roll (R2R), screen-printing system (see Figure 1).
FIGURE 1. Comparison of traditional sheet-based (left) and new gapless R2R screen printing (right). Source: Komori America
NanoPrintek (Auburn, AL) is developing an inkless, multi-material printing technology, in which pure nanoparticles of various materials are generated in situ and on-demand, then directed through a printer nozzle and laser-sintered in real-time. This system promises multimaterial printing of hybrid and tunable nanocomposite materials and structures. The use of dry printing avoids the need for complex ink formulations, surfactants/contaminants, limited printing inks and high-temperature post-processing to sinter the particles and remove surfactants.
Materials innovations: Substrates, conductive inks and other materials are critical to economical fabrication of durable flexible- and hybrid-electronics systems. Several presentations added to the growing library of materials that developers may be able to choose from.
Electroninks (Austin, TX) has developed particle-free, metal complex inks using metal-organic decomposition in which solvents are combined with metal precursors to form complexes that are free of particles and can be cured at low temperatures. The company has used the process to produce silver, gold and platinum inks, with nickel and copper formulations under development. Such inks are intended for use in EMI shielding, while other applications are addressable via a variety of deposition methods (spray, screen, aerosol-jet, inkjet). One application spray-coats the backside for metallization of wafers.
Auburn University (Auburn, AL) reported on the initial characterization of water-based inks for printed conductors. These materials have the beneficial property of not containing the volatile solvents that typical solution-based inks employ, but the impact on performance has not been rigorously evaluated yet. The team deposited test traces via direct-write, aerosol-jet and inkjet systems, before attaching components to the traces with electronic-component assemblies (ECAs) and low-temperature solvents with good results.
Fraunhofer ENAS (Chemnitz, Germany) proposed Parylene as a new substrate material. A thermoplastic polymer, Parylene has a variety of unique properties, such as optical transparency, biostability, biocompatibility, thermal stability and low permeability to gases and water vapor – all useful for a variety of end-use applications. Fraunhofer has used Parylene as a substrate, a dielectric between the metallic redistribution layers (RDL), as well as for encapsulation. The Parylene is formed through a chemical vapor deposition (CVD) process on a sacrificial silicon wafer, metallized, patterned and separated from the wafer, forming a printed circuit board only 20 nm thick – hundreds of times thinner than rigid PCBs.
Flexible electronics projects driving medtech innovation: The medical-technology sector welcomes the ability to conform electronics to the human body. SEMI Nano-Bio Materials Consortium (NBMC) is a sister community to FlexTech under the SEMI umbrella. The group identifies the gaps in medical monitoring and augmentation and invites research proposals to overcome some very big hurdles. Among the biggest challenges have been to consistently gather fluids interstitially (under the skin) and create multi-sensor systems for physio-cognitive states, and many of other medical-sensor projects.
Soft robotics: One application to which flexible and hybrid electronics manufacturing is uniquely suited is the creation of devices able to locomote, grasp and carry out other mechanical motions. By being flexible – or soft – these devices can access interiors of complex industrial systems and interact with difficult-to-access components.
Once again at FLEX 2023, GE Research (Niskayuna, NY) discussed the need for and challenges of developing bio-inspired soft robots for inspection and repair of high-value industrial assets. GE is developing a soft, electronic skin-innervated robotic worm (Sensiworm) for rapid maintenance of strategic assets. The work enables robust, “three-degree-of-freedom”
locomotion in unstructured environments, including against gravity. The worm also sports highly stretchable, conformable multiparameter sensors capable of simultaneously measuring temperature, humidity and material characteristics (cracks, corrosion, coating thickness) and can transmit power and video signals.
The University of Colorado-Boulder described research on soft robots using hydraulically amplified, self-healing electrostatic actuators. The focus is on developing modular robots based on high-voltage soft actuators with FHE control electronics and thin-film drive electronics (see Figure 2).
FIGURE 2. Example of the modular untethered robotic system. Source: Greg Whiting, UC Boulder
Network to collaborate: Printing accuracy and interconnecting printed electronics with a semiconductor continue to provide the greatest challenges to flexible-electronics manufacturers. Thin, flexible substrates, bare die, and combinations of printed and small-format packaged components require the use of additive processes for circuitization, mechanical attach and encapsulation.
To remain current on FlexTech projects, workshops and news, register for the group’s Interest Lists at https://discover.semi.org/technology-communities-subscription-registration.html
Resources
1. Komori America Corp., www.komori-america.us/contact-us
2. NanoPrintek, https://nanoprintek.com
3. Electroninks, https://electroninks.com
4. Auburn University, www.auburn.edu
5. Fraunhofer Institute for Electronic Nano Systems, www.enas.fraunhofer.de/en.html
6. GE Research, www.ge.com/research
Gity Samadi, Ph.D., senior dir.-R&D Programs at SEMI FlexTech (Milpitas, CA), holds a Ph.D. in Engineering Physics from the Vienna University of Technology (Vienna, Austria). She has received corporate awards, has five issued patents and has numerous technical publications. Gity has 20 years of experience in Hard Disk Drive (HDD) technology and the semiconductor industry at various levels from engineering to technical-program management and senior management. Gity began her career at IBM (Magnetic Recording Head Fabrication) in San Jose and subsequently worked at Hitachi Global Storage (HGST), Western Digital, Headway (TDK) and Lumentum. She currently leads FlexTech and NBMC R&D programs and the ESDA (Electronic System Design (ESD) Alliance) and ITL (IT Leadership) technical communities. Gity can be reached at email: gsamadi@semi.org, www.FlexTech.org.
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