Sandia’s Research on Thin Films Could Influence Nuclear Research and Development

Paul Vianco of Sandia National Laboratories believes his research on thin films can boost the U.S. industry by influencing R&D based on nuclear weapons.

Sandia National Laboratories researcher Paul Vianco works on thin films, nanometer-thick layers of metal that can be defined into precision electrical circuits. He won the Surface Mount Technology Association’s 2015 Best of Proceedings award and will be honored with other winners at the association’s meeting in September. (Photo by Randy Montoya)

Since the 1970s, researchers working out of laboratories have borrowed research work conducted to sustain the weapons program and presented or published parts of the research at various technical conferences. Vianco calls this activity passive tech transfer.

Engineers would just fill rooms. They wanted to hear what we were doing, not only because our research represented the ‘latest-and-greatest,’ but more so because it was applied technology. This was information that folks ate up because they could take it back to their companies and put it directly to use on their products.

Paul Vianco, Sandia National Laboratories

Recently, Vianco won the 2015 Best of Proceedings award from Surface Mount Technology Association for the paper: “Establishing a Ti-Cu-Pt-Au Thin Film on Low Temperature Co-Fired Ceramic Technology for High-Temperature Electronics.” The paper was co-authored by Jerome Rejent, Alice Kilgo, Bonnie McKenzie and Amy Allen of Sandia; recent Sandia retiree Mark Grazier; and William Price of the Kansas City National Security Campus (KCNSC) and Esteban Guerrero, now retired from KCNSC.

The association will be honoring the winners of the Best Papers awards on September 27 at its conference in Rosemont, Illinois. Vianco was also the recipient of the Best of Proceedings paper in 2012.

Thin films are nanometer-thick metal layers that can be defined into accurate electrical circuits matching conventional printed circuit boards. The thin film is patterned into a circuit through photolithography methods instead of a built-up or laminated copper conductor circuit. The advantage here is miniaturization with spaces and finer lines, thereby enabling the electronic component to be created smaller and perform more simultaneously.

Smaller components weigh less and use less power. We reduce what industry refers to as ‘SWaP,’ or size, weight and power.

Paul Vianco, Sandia National Laboratories

Data could be utilized to additionally develop components

The research paper from Sandia gives the electronics sector data that can be implemented to further advance thin film-on-low temperature co-fired ceramic (LTCC) parts known as hybrid microcircuits, for high-temperature electronics.

Vianco foresees a new generation of these types of LTCC components which will be a blend of functionality, miniaturization, and the ability to endure adverse environments, and are fabricated by frequently used photolithography methods.

The solder interconnection reliability data will enable use of these products in applications that include down-hole oil and gas exploration as well as renewable energy development.

Paul Vianco, Sandia National Laboratories

These types of hybrid microcircuits also have an important possibility for communications electronics and sensors in space probes, he stated.

Ever since its innovative development of LTCC technology on thin film some time ago, Sandia has been in partnership with the Kansas City National Security Campus. Sandia’s nuclear weapons life extension program funded the research along with Sandia’s and KCNSC’s Enhanced Surveillance Campaigns, which aid stockpile stewardship. KCNSC constructed the LTCC and deposited the thin films, while Sandia created and executed the test processes and utilized its modern microanalysis capabilities for failure mode analyses.

Vianco was happy with this partnership.

It’s really a case where we took the application, understood what information was needed to ensure producibility and reliability of the solder interconnections and developed a test in collaboration with our KCNSC partners. The result was strength and failure analysis information that significantly enhanced the ability of Sandia to design new components and of KCNSC to fabricate them into high-reliability products. We’ve sort of come full circle: We identified the need, developed an experiment and obtained test data that supported the application. Publishing the results made the data available to the U.S. electronics industry.

Paul Vianco, Sandia National Laboratories

Work offers electronics industry new applied technology

The award-winning research analyzed the mechanical properties of solder joints constructed based on a thin film conductor pattern, which was deposited on the surface of an LTCC substrate. Co-fired means individual layers, placed one on top of the other, are fired together at elevated temperatures to develop the internal, multilayer circuitry and interconnections that are trademark LTCC technology.

Vianco and his coworkers created a basic technique to evaluate solder joint strength on the modern thin film circuits. The method provides a way to describe assembly processes and establish the long-term dependability of solder interconnections for vital, high-frequency parts.

Thin film conductors are not a new circuit technology, but they are still in relative infancy within the high-reliability electronics industry. A lot of hybrid microcircuits still rely upon the old thick film conductor technology, which uses screen or stencil printing to define the electrical circuit. We’ve used it for years on high-frequency components. But it’s limited in terms of achieving better SWaP for those products because we can’t miniaturize it very much more than we’ve already done.

Paul Vianco, Sandia National Laboratories

The electronics sector is keen on enhancing product performance, but frequently does not fully understand the complexities of interconnections-plus-thin films as a materials structure, he explained. “It’s been kind of a mystery in terms of how solder joints made to thin film conductors stay attached to the LTCC substrate, but I think they now see that what we’re doing is valuable in furthering this technology. For those who never thought of using thin film-on-LTCC, those folks are saying, ‘Maybe now we do know enough about this technology to try it on our products.’”

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