Drilling of Transparent Materials with Ultrashort Laser Pulses (LMF4-M407) and found that using a water bath improved the taper while performing bottom-up percussion drilling of sapphire. In addition to optimizing the laser-only ablation process, the back side only water bath removed ablated material that was recast onto the sidewalls more efficiently than drilling without one, reducing the biggest process limitation, and allowing higher maximum drilling depths. The water bath’s enhanced debris removal through capillary action also removed the taper and any dependency on drilling speed, so the process was demonstrated on CT90 glass as well with similar excellent results.


With numerous talks on battery applications this year, one of the most well-attended talks was Joanna Helm’s from Fraunhofer ILT, Connecting Battery Cells by Aluminum Ribbon Bonding using Laser Micro Welding (LMF8-M802). She presented her work that integrated a laser welder with a conventional wire bonder complete with automated ribbon supply and integrated cutter for high speed, efficient bonding when connections to large numbers of battery cells are needed. She demonstrated initial results of connecting 6082 aluminum alloy ribbon with two welds on the two poles of a battery pack using an SPI 400 W fiber laser with different process variables such as weld depths, weld lines, overlap, laser power and pulling angle. Mechanically robust connections were made, and characterization and optimization for defect reduction is ongoing.


Many talks featured medical applications, and Togo Shinonaga’s invited talk from Okyama University, Japan, Control of Surface Profile in Periodic Nanostructures Produced with Ultrashort Pulsed Laser (LMF6-M601) showed how creating structures on the surface of a biomaterial with lasers may eventually be able to control cell spreading. He demonstrated that cells aligned to grooves that were cut with 100-1000 nm periods in titanium plates, and determined the optimal laser properties for creating favorable directions, aspect ratios and heights of the channel structures.


Nanomanufacturing Conference Technical Highlights The Nanomanufacturing Conference, chaired by Professor Yongfeng Lu from the University of Nebraska-Lincoln, had many talks on using lasers for nanoscale manufacturing, and had sessions on photovoltaics, advanced energy devices, battery materials and 2D materials.


Costas Grigoropoulos from the University of California Berkeley gave an invited talk, Laser-Assisted Processing of Layered Dichalcogenide Semiconductors (Nano1-N101) about their new laser-assisted doping process that allows high performance devices to be fabricated from ultra-thin films of 2D transition metal dichalcogenides (TMDCs). The laser-assisted Chemical Vapor Deposition process used multiple lasers at different wavelengths and standard dopant gases to dissociate gas


18 LIATODAY FOCUS: YEAR END REVIEW NOVEMBER/DECEMBER 2016


molecules and create vacancies in the thin film to be doped. Thin film transistors were formed on a flexible polymeric substrate with single and bilayer flakes of MoS2 and WSe2


materials as the active semiconductor channel. The and single crystal WS2


successful doping process was selective and tunable, and device performance was reliable and stable for months.


Another invited talk addressed the topic of 3D IC fabrication, important as more microelectronic devices become smaller, lightweight and lower power. Koji Sugioka spoke about his research team’s work at the RIKEN Center for Advanced Photonics in Japan in his talk Tailored Femtosecound Bessel Beams for Fabrication of High aspect-ratio through Si Vias (Nano1-N102). To create small holes in 50 µm and 100 µm thick silicon that are taper free and almost taper free, the group used laser drilling in air with two different Binary Phase plates (BPP) that filter the bessel beam’s phase and reduce the amount of energy needed to fabricate TSVs. Compared to Gaussian-shaped beams and Bessel beams that used an Axicon lens alone, SEM images before and after cleaning confirmed the vias could be produced with superior profiles.


A well-attended talk from the Advanced Energy session on generating flexible printed “batteries” for the next generation of bendable, wearable and portable devices was given by Anming Hu: High Performance Hybrid Supercapacitors on Flexible Polyimide


Sheets using Femtosecond Laser 3D Writing


from the University of Tennessee Knoxville. He demonstrated writing 3D battery-style supercapacitor cells by laser radiating nanoparticles on Kapton insulator tape that produced porous carbonized structures that changed their conductivity from insulating to conducting. After charging to 3.7 V for 3 minutes, they powered 1 cm x 1 cm LEDs and retained 97 percent efficiency over 2000 cycles for more than a month, behaving similar to a coin-style battery.


Networking and Access to Industry Leaders ICALEO not only offers the industry’s most comprehensive technical content but also offers access to influential leaders at Fortune 500 companies across manufacturing industries in Automotive, Aerospace, Commercial Electronics, Communications, Medical Device, R&D and Semiconductors.


The Sunday Welcome Celebration, complete with music from the industry’s own Ron Schaeffer, Henrikki Pantsar and guest musician Matt Henry, and Monday night’s President’s Reception were well-attended opportunities to meet members of the LIA Executive Committee and Board of Directors, as well as connect with colleagues from around the world.


Dr. Kaushik Iyer, a first-time attendee from Johns Hopkins University Applied Physics Department, said the conference was the “perfect size, excellent content, global networking!” Mr.


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