Printed batteries offer thinness and flexibility, enabling new applications, but their production is deceivingly complex. Gunter Hübner from Stuttgart Media University offered some insights at the e-Swiss conference last week. The first slide shows an excellent benchmarking of different battery chemistries for printed batteries. The Zinc/manganese dioxide system is the most popular option. As shown in slide 2, we see that these batteries can be manufactured in two architectures: coplanar and stacked. The former is simpler to print and is more flexible, but offers lower performance. In slide 3, a closer look at the layers in a stacked printed battery is offered. As seen here, even this so-called 'simple' device involves many printing step! Since Ag is not electrochemically inert, a carbon black layer is also printed. The particles in the anode and cathode are typically in the 10-50um range and thus can only be screen printed. Note that the cathode is typically 1.5x thicker than the anode. The printed battery layers typically have 150um thickness and the batteries achieve something in the range of 2-6mAh per cm2. Furthermore, in printing them, strong adhesion of the electrodes to the current carriers is essential. All these show how complicated it is to print even a simple zinc/manganese battery - it involves significant know-how and learning, which can not be achieved overnight! The final slide shows an elegant clever approach to printing the system. Here, the materials are printed on a planar sheet and then folded to create the full battery stack. This technology is now being commercialized by VARTA AG . It also has commercial orders in applications such as tracking items in the chemical industry. To learn more about printed batteries join us on 12 & 13 October 2022 | Eindhoven, Netherlands at the TechBlick show- where the printed electronics community connects www.TechBlick.com/electronicsreshaped

At the e-Swiss conference last week we came across an interesting technology showcased in a poster. Here, the process is called "Multi-metal electrohydrodynamic redox 3D printing" and developed by R. Spolenak's team at ETH Zurich Slide one shows the working principle: "Solvated metal ions Mz+ are generated within the printing nozzle via electrocorrosion of a metal electrode M0 immersed in a liquid solvent. (2) Ion-loaded solvent droplets are ejected by electrohydrodynamic forces. (3) Upon landing, Mz+ ions are reduced to zero valence metal M0 through electron transfer from the substrate." As shown the metal ions are generated in a solvent from an immersed wire thus eliminating the need for a liquid formulated ink in the deposition technique. Furthermore, as seen below, the ability to print multi materials using a single voltage-controlled nozzle enables one to adjust the chemistry and composition of the deposited materials on-the-fly, thus not only enabling layer-by-layer variation of materials but also enabling much more granular changes in composition and alloying Given that this is based on electrohydrodynamic printing- in which the droplets are injected under the application of a voltage- the feature sizes are in the sub-micron range. Slide 2 shows various examples of printed Cu structure, using the extreme control of the process as well as its excellent feature size capability This is a very promising technology with a high potential for future development. It is of course still early stage but could it be the basis of a holy grail process which combines ink-free, micro-scale features, digital printing, and on-the-fly multimaterial compositional control? To learn more about printing electronics join us in Eindhoven where the printed electronics community connects: https://www.techblick.com/electronicsreshaped Source: https://doi.org/10.1038/s41467-019-09827-1

Nano-Ops is commercialising an automated wafer-based process and fab-in-a-box based on the directed assembly technology which can 'print' features down to 20nm. Here, In the first step a pattern is first etched into a template wafer. This is achieved using conventional photolithography-based techniques. Next, the template wafer is 'inked' using a directed assembly process. In the key step, the template wafer is immesed in a solution containing the nanomaterial of choice - which could, for example be metals (Au, Ag, Cu, etc) or even organic polymers. Under the application of a voltage, the directed assembly process ensures the inking of the template wafer, i.e., the deposition of the nanomaterials onto the etched patterns on the template wafers. The 'inked' wafer is then used as a printing plate. The automated machine takes the wafer and brings it into precision contact with the target substrate, which could be PET. Under pressure, contract printing takes place, transfering the ink from the inked wafer onto the final substarte. The process is then repeated to achieve high-throughput wafer-based printing. The template wafer is said to be resubale upto 100 times or more. Nano-Ops has shown that all types of materials can be deposited using various directed assembly techniques (electrophoretic and fludic). Slides one and two below shows example of different materials and patterns deposited on an patterned wafer (on the template wafer) using this technique. The feature sizes range from a few mironmeters down to 20 nanometers. In slides three and four show an example of a fan-out circuit printed. The gold structure are 12um feature. The thicknesses are typically between 300nm and 1um with upto 50% of bulk conductivity achieved on the inked wafer. Indeed, as seen in slide 4, the I-V characteristics of the 800nm-thick 'printed' Cu lines are comparable to that of 800nm sputtered Cu lines. This is a unique technique full of potential. When the entire process (directed assembly + alignment + transfer + consistency across multiple print runs ) is optimized for a given material set and layer structure in a given application, then it could lead to rapid 'printing' of nanoscale complex multiplayer and multi-material devices at costs far below standard silicon fabs and at resolutions far beyond the reach of stnadard printing techniques. Ahmed et al will be showcasing and presenting this technology in Eindhoven on 12-13 OCT 2022 at the TechBlick show. Learn more here https://www.techblick.com/electronicsreshaped

Speaker: Margaud Lecuyer | Company: BlueSolutions | Date: 9-10 Feb 2022 | Full Presentation BlueSolutions has been commercializing all-solid state batteries since 2011. EVs, buses and stationary applications are the main targets of its research and development program. After more than 15 years, this Bolloré group subsidiary masters all the industrial processes for the production of a unique solid state battery technology. The know-how goes from the transformation of the lithium ingots to the integration of the battery packs within the applications. Importantly, a low-ecological footprint process has been stated for both the positive electrode and the polymer electrolyte manufacturing. In order to get incomparable energy densities, today, all the industrial actors of lithium batteries are hardly working on the lithium metal technology. In this context, BlueSolutions has a unique 10 years feedback regarding both the behavior of this special anode and of the solid-state electrolyte. After having spread the first pack generation for 8 years all-over the world, an optimized 650V battery pack addressing the e-buses market is being delivered for one year. To match with customers expectations this new generation offers optimized performance and a very long cyclability. In the meanwhile, BlueSolutions has already started working on its future generation products. While the current battery is LFP-based and cycles at a nominal temperature of 80°C, a lot of efforts are dedicated to improve the actual chemistry. Research programs are conducted on the development of a new positive electrode with higher energy density, new electrolytes that will be compatible with high-voltage materials and which have high conductivity at ambient temperature and optimized lithium electrode. In fine, the goal is to keep the intrinsic safety of the polymer solid electrolyte, while benefiting from the promising performances of new electrode materials. Join TechBlick on an annual pass to join all live online conference or online version of onsite conference access library of on-demand talks (600 talks + PDFs) portfolio of expert led masterclass year-round platform https://www.techblick.com/ Our next battery-related event will take place on 15-16 FEB 2023, covering 1) Solid-State Batteries: Innovations, Promising Start-Ups, & Future Roadmap 2) Battery Materials: Next-Generation & Beyond Lithium Ion The speakers include: General Motors, Graphenix Development, Brookhaven National Laboratory, Fraunhofer IKTS, RWTH Aachen University, Lawrence Livermore National Laboratories, Meta Materials Inc, Skeleton Technologies, Solid State Battery Inc, Argonne National Laboratories, OneD Battery Sciences, VTT, Leyden Jar Technologies B.V., b-Science, Rho Motion, Wevo-Chemie, LiNA Energy, CNM Technologies, Ionblox, Empa, Zinc8 Energy Solutions, Avicenne Energy, Echiontech, South8 Technologies, Basquevolt, NanoXplore, Chasm, Li Metal, Sila Nanotechnologies, Quantumscape (tentative), Fraunhofer ISI, etc https://www.techblick.com/

of Today’s Advanced High Performance Systems Speaker: Alfred Zinn | Company: Kuprion Inc| Date: 10-11 March 2021 | Full Presentation In today’s market, electronic systems have become ever more complex while current design methods for PCBs are limiting and inadequate. New approaches are needed to meet reliability demands for increased power dissipation and thermal management of advanced high performance systems. In this presentation, Kuprion, a spinout of Lockheed Martin, will not only detail these challenges, but demonstrate how new, innovative technologies like Active Cu (ActiveCopper™) filled thermal vias are addressing the requirements for more robust interconnect structures to enable thinner, cooler, more compact and reliable operating devices. Join TechBlick on an annual pass to join all live online conference or online version of onsite conference access library of on-demand talks (600 talks + PDFs) portfolio of expert led masterclass year-round platform https://www.techblick.com/ And do NOT miss our flagship event in Berlin on 17-18 OCT 2023 focused on Reshaping the Future of Electronics. This event attracts 550-600 participants from all the world and offers a superb ambience and dynamic exhibition floor. To learn more visit https://www.techblick.com/electronicsreshaped To see feedback about previous event see https://www.techblick.com/events-agenda

Printable dielectrics for RF, Bonding in heterogeneous integration Welcome to this week edition of our technology newsletter with a focus on additive electronics. One housekeeping note: the masterclass and tour spaces taking place before our inaugural conference and exhibition in Eindhoven (Future of Electronics RESHAPED | 12-13 OCT 2022) are almost full. We are now in tocuh with venue to see if additional space can be released. We recommend that your reserve your spot ASAP. Topics for this week: EHDjet printed QDs on microLEDs | R2R single-step gravure printed perovskite photovoltaics | Gravure printed microbumps for microLEDs | 3600ppi full color "silicon" displays | Lasers in microLEDs | Printable dielectrics for RF and MW devices | Pitch scaling and bonding in heterogeneous integration | Microfluidics and Electrohydrodynamic printing | Graphene to market: breaking down regulatory barriers. High-PPI RGB microLEDs, printed electronics, and quantum dots? The three themes are closely linked since QDs can be digitally printed as color conversation materials atop blue microLEDs to enable wide color gamut RGB uLED displays without requiring a separate transfer step for each color. Join TechBlick's event on microLEDs to learn more www.TechBlick.com/microLED Inkjet is the common technology investigated for such a purpose. As shown below by Prof.Armin Wedel, however, its 4pL droplet is too large, allowing at best a 40um pixel and not able to reach even 850 dpi. Electrohydrodynamic printing (EHD) can however address this issue. In EHD, the droplets are pulled out by an electric field from a nozzle which sits close (50um or so) to the surface and thus requires a good printing facility. As shown below, the droplet volume is only 0.5pL, enabling 1-10um pixels in the lab and 15um reproducibly. This will enable one to achieve 850ppi and 1000ppi! Slide 2 shows an example of a QD color filter (QD-CF) for a microLED display deposited using EHDJet. Here, 15um pitch is reported, achieving 1000ppi. The roadmap will be to evolve the technology towards even 2000ppi! These are excellent advacements of the art and technology, paving the way for the development of high-PPI microLED technology. Of course, EHDJet is a relatively new technology. It is mainly single head and slow, although multi-head print heads are emerging. Nonetheless, it is an elegant solution for depositing color filters on high-PPI microLED displays. To learn the latest about these technologies joint TechBlick's specialist event on microLEDs and Quantum Dots where Prof. Wedel will also present: www.TechBlick.com/microLED You can hear from the likes of Samsung, Sharp, Yole, ASMP, Coherent, Nanosys, CEA, AUO, Allos Semiconductor, KIMM, Luxnour, Omdia, Playnitride, micromac, and many many more R2R gravure print perovskite photovoltaics in a single step without antisolvents? This would be a major step towards industrialization. Here, we discuss the transition from 2-step printing to one step printing with antisolvent to one-step printing with no antisolvents. Riikka Suhonen et al discussed the latest developments at TechBlick's event in Dec 2022. Here is a summary 2-step approach: In general, most approaches are based on a 2-step printing in which the lead iodide (from PbI2-DMSO ink) is first gravure printed on a printed SnO2 NPs layer and then dried. The DSMO is then washed away in a water and isopropanol path and the remaining porous layer is dipped into a chemical second path to form MAPbl3. The 'pilot' R2R runs yield PCE of 9.7%. This approach requires two chemical steps, slowing the process. Furthermore, handling the porous Pbl3 layer is difficult in R2R environment and oncersion to FA- or FACs-perovskite challenging 1 step printing + antisolvet: the standard antisolvent is ether but this can not be printed due to high volatility. Therefore, there has been huge effort in developing an antisolvent which could be printed industrially and was environmentally friendly. VTT et al developed the tBuOH:EA system. This way they achieved fully R2R gravure printed perovskites with efficiency of 13.8%. This is an elegant solution. Nonetheless, There is a desire to eliminate the antisolvent step as it will require a spray or bath step together with solvent fumes. 1 step printing: Here they used starch as a rheology modifier with perovskite precursor, forming a viscous ink which can be used to print well-defined patterns. In this R2R 'lab' printing starch-based MAPb3I inks they used IR annealing and hot air annealing. The first lab runs showcased a champion result of PCE 9.9%. This is still an early stage development but shows that reasonble efficiencies can be achieved using R2R gravure printing with only a single step! Of course - these results are early stage. Lifetime remains an issue and development area. Nonetheless, this is an important field to watch further. We will soon announce the agenda for our 2022 edition of TechBlick's event on organic, perovskite, and tandem photovoltaics. Riikka Suhonen, Antti Kemppainen, Ari Alastalo, Jani-Mikael Kuusisto, Thomas Kraft, Henrik Sandberg Gravure printed microbumps for microLEDs As microLEDs inevitably shrink in size, the micro-bumping requirements for the microLED dies becomes more challenging. Direct wafer-based printing based on gravure offset techniques offers a promising solution in this regard. Indeed, this is another field where printed electronics can play a role. Komori has recently achieved excellent results, which will be unveiled at TechBlick's upcoming microLED event on 30 Nov-1 Dec 2022: www.TechBlick.com/microLED As seen in the slides below, gravure printing can print microbumps printed using flux paste, achieving a printing precision of 5 µm within a range of 300 mm. The first slides show the precision of the printing position on a wafer. In particular, it compares it with screen printing, showing how gravure printing advances the fine feature printing capability w.r.t screen printing (+/-10 um although screen printing too can and will also advance) As shown in slide two, the minimum diameter that can be printed with SAC (Sn, Ag, Cu) solder paste is 6 μm and the distance between the centers of the bumps is 30 μm. Reflow has been successful with a minimum diameter of 10 µm. This way for example, a microLED die in the size of 30um by 50 or 80um can be supported. Furthermore, as shown in slide three, this technique also offers the possibility to control the thickness by printing several diameters. The smaller the bump diameter, the higher the aspect ratio. This are very nice results, showing the viability of gravure printing technique for microbumps. This technology can support current and near-term generations of microLEDs but will it evolve as microLED dies further shrink in the longer term? Join Komori and other members of the community to learn about all aspects of microLEDs from GaN microLED technology to transfer and tiling technology to bumping and color conversion technology and beyond. You can hear from the likes of Samsung, Sharp, Yole, ASMP, Coherent, Nanosys, CEA, AUO, Allos Semiconductor, KIMM, Luxnour, Omdia, Playnitride, micromac, and many many more www.TechBlick.com/microLEDs “Silicon” Displays with an incredible 3600ppi full color using microLED and QD technology? Sharp (HIRANO Yasuakie et al) will join us from Japan to explain this technology at the upcoming TechBlick event on microLEDs and quantum dots (www.TechBlick.com.microLEDs). As shown in the slide below, first blue-only uLEDs are formed on a sapphire substrate. Here, one LED array contains 352 x 198 micro LED dies of 24 um x 8 um in size. In parallel, an LSI chip containing the driving circuitry is formed on a silicon wafer. Here, the cathode (N-type electrode) and anode (P-type electrode) are fabricated for each micro LED die to apply driving voltage independently to each die. The Au bump electrodes are fabricated in accordance with the pitch of the LED dies. The two substrates are flip-chip bonded using Au-Au bonding. Here one can already see the parallel to the silicon and optoelectronic industry (vs. the traditional thin film display industry!). Next, the sapphire layer is removed via laser lift-off. Finally, Cd-free quantum dots (green and red) are deposited atop the microLED dies to enable R G color conversion. This way one achieves RGB colors. The device architecture is shown in slide 2- here one can see the location of GaN uLED dies, Au bumps, as well as light shielding walls and quantum dots (QDs). This way, a full color 1,053 ppi display is formed. However, given the small size of the emissive area of uLEDs, the brightness is low. An innovative solution here is to switch from individual driving cathode electrodes to a common one, thus freeing up more spaces for uLEDs. As shown in slide three, the light emission in one pixel was improved from 23% to 38%. As a result, brightness of 11 knits was achieved. This is an excellent progress. Of course, it is not the final game as even at 11 knits the brightness is not yet not sufficient for outdoor AR applications. Join us and your industry peers on 30 NOV – 1 DEC 2022 at our first-ever specialist microLED and QD event to hear more about this technology from Yasuakie-san et al: www.TechBlick.com/microLED How lasers help in MicroLED display production? See slides below to learn. One of the biggest manufacturing challenges in uLED display production is the transfer step given the speed and yield requirements. As shown in the slides below by Oliver Haupt from Coherent Inc., lasers can play an important role in this step, both when all three colors (R G B) microLEDs and also when only blue microLEDs need to be transferred. To learn more join TechBlick's first ever specialist event on microLEDs on 30 NOV - 1 Dec where Oliver will present this technology www.TechBlick.com/microLED The process flow for both cases is shown below. In case of RGB MicroLEDs, first a temporary carrier is attached to the sapphire substrate on which GaN uLEDs are grown. Laser Lift Off (LLO) is deployed to de-bond the sapphire substrate, releasing the carrier wafer with the detached GaN microLEDs. Next, controlled UV spots are used to release the individual microLEDs onto the final substrate holding the TFT active backplane layers. These process can be repeated three times, each time for a different uLED color. In all steps, of course, excellent and optimized control of the laser profile/parameters in harmony with the right adhesive material properties are required. In the case of blue-only microLEDs, the final backplane substrate is brought into contact with the GaN sapphire substrate. The GaN uLEDs transfer to the final substrate via the LLO process. Three color capability is then achieved by color conversation, e.g., QDs or small-sized phosphors. The results show the example of microLED RGVB transfer. The parameters are shown in the slide including microLED size, pitch, laser energy density, donor-receiver distance, etc. It can be shown that a different color is transferred with each shot. Thus, in three shots all R G B microLEDs are placed at the right spot! As the subset in slide 2 shows, the laser can in each step/shot process an area of roughly 2.83cm2. To learn more join our world-class event on microLEDs and QDs. More info on www.techblick.com/microLEDs Heterogenous integration is the key to the future of computing Here, the limiting factor is often the interconnect density (pitch) as well as bandwidth and energy consumption of the I/O. Indeed, as we move towards platforms where multiple dies, potentially from different foundries, are all integrated into the same package, the issue becomes extremely important because die-to-die communication becomes the bottleneck. The first slide below are from Intel, presented by Dr Sabi at a conference in Sept 2021 online. Here, you can see the intended evolution of the technology. First, EMIB was launched. Here, a silicon bridge with <55um pitches serves as a small (2x2mm to 8x8mm) communication link between two separate dies in a package. This approach is an alternative to the standard silicon interposer technology. Next was the development of Foveros platform, allowing face-to-face integration of dies from different foundries onto a single package all connected via silicon base logic die. As you can see, this technology will evolve with aggressive pitch scaling and a potential transition to direct Cu-to-Cu bonding from microbumps. The second slide shows this trend further. It shows the evolution of interconnect pitch as heterogeneous integration advances. The common technology is flip chip BGA (FCBGA). The pitch here is limited to around >120um. Next, EMIB was launched. Here, the pitch was reduced to 55um thanks to the silicon bridge technology. Now there is Fovereos which is based on die on wafer technology. The next generation will based on HBI or hybrid bonding. These heterogenous integration platforms can enable the integration of dies from different foundries. The challenge is though that each foundry has its own I/O designs, making easy compatibility difficult. It is helpful for the industry to develop common standards to enable a plug-and-play solution. The third slide shows the need to transition towards Cu-Cu bonding. As the left chart shows, solder based microbumps can support the technology until around 15-20um. Beyond this pitch level, a transition to Cu-Cu bonding becomes necessary. With this transition comes the possibility to increase bump density to over 10000/mm2. This is vital so that the I/O size and bandwidth do not limit overall system performance in complex multi-die packages. But will all suffice? The fourth slide shows need to transition from Cu bonding to optical I/O technology. As the table shows, optical I/O (OIO) can increase shoreline density by a factor of 4, reaching 1.6 Tb/s/mm. It will also improve power efficiency by some 35%. Finally, as shown in the fifth and final slide, this technology will need to evolve. The current (Sept 2021) demonstration was for an on-package OIO able to achieve >1Tpbs/mm @ 6 pJ/bit. The target is a fully integrated OIO able to achieve 10 Tbps/mm @ just 1pJ/bit conversation. Heterogeneous integration is THE technology space to watch babak sabi Challenge: printable dielectric materials for RF and MW devices? The dielectric material is often the bottleneck against fully printed high-performance RF and MW devices. This is often a neglected challenge as the emphasis is mainly on the conductive layer. Indeed, the development of a suitable low-loss digitally-printable dielectric material with high and controlld resolution is a technical challenge. In this 3-min video, Yuri Piro from University of Massachusetts Lowell explains why this is challenging: "So coming up with a non-polar material that you can form on the spot with low processing conditions and low polarity is difficult and you really can't use these conventional approaches." Microfluidics and Electrohydrodynamic printing (EHD)? EHD is a promising digital printing technology for going beyond the resolution limits of inkjet. Most examples showcase electronic or display related applications. However, in a recent TechBlick talk, as shown in slide 1, Dr Aart-Jan Hoeven showed an example in microfluidics where EHD could delvier value. Here, this technology could enable the electrode widths or pitches to be narrowed from 30-40um (possible with industrial inkjet) to perhaps 1-5um using EHD, thus saving space. This will support the miniaturization trend of microfluidics, making possible to even integrate them into the human body. In slide 2 DoMicro BV 's laboratory-scale nano printer can be seen in more detail. It is able to deposit ultrafine features digitally! This DM50-ENP printer is generating significant interest and was developed as part of E-Nanoprint-Pro project

high-PPI RGB microLEDs, printed electronics, and quantum dots? The three themes are closely linked since QDs can be digitally printed as color conversation materials atop blue microLEDs to enable wide color gamut RGB uLED displays without requiring a separate transfer step for each color. Join TechBlick's event on microLEDs to learn more www.TechBlick.com/microLEDs Inkjet is the common technology investigated for such a purpose. As shown below by Armin Wedel, however, its 4pL droplet is too large, allowing at best a 40um pixel and not able to reach even 850 dpi Electrohydrodynamic printing (EHD) can however address this issue. In EHD, the droplets are pulled out by an electric field from a nozzle which sits close (50um or so) to the surface and thus requires a good printing facility. As shown below, the droplet volume is only 0.5pL, enabling 1-10um pixels in the lab and 15um reproducibly. This will enable one to achieve 850ppi and 1000ppi! Slide 2 shows an example of a QD color filter (QD-CF) for a microLED display deposited using EHDJet. Here, 15um pitch is reported, achieving 1000ppi. The roadmap will be to evolve the technology towards even 2000ppi! Of course, EHDJet is a relatively new technology. It is mainly single head and slow, although multi-head print heads are emerging. Nonetheless, it is an elegant solution for depositing color filters on high-PPI microLED displays. To learn the latest about these technologies joint TechBlick's specialist event on microLEDs and Quantum Dots where Prof. Wedel will also present: www.TechBlick.com/microLED You can hear from the likes of Samsung, Sharp, Yole, ASMP, Coherent, Nanosys, CEA, AUO, Allos Semiconductor, KIMM, Luxnour, Omdia, Playnitride, micromac, and many many more

As microLEDs inevitably shrink in size, the micro-bumping requirements for the microLED dies becomes more challenging. Direct wafer-based printing based on gravure offset techniques offers a promising solution in this regard. Indeed, this is another field where printed electronics can play a role. Komori has recently achieved excellent results, which will be unveiled at TechBlick's upcoming microLED event on 30 Nov-1 Dec 2022: www.TechBlick.com/microLEDs As seen in the slides below, gravure printing can print microbumps printed using flux paste, achieving a printing precision of 5 µm within a range of 300 mm. The first slides show the precision of the printing position on a wafer. In particular, it compares it with screen printing, showing how gravure printing advances the fine feature printing capability w.r.t screen printing (+/-10 um although screen printing too can and will also advance) As shown in slide two, the minimum diameter that can be printed with SAC (Sn, Ag, Cu) solder paste is 6 μm and the distance between the centers of the bumps is 30 μm. Reflow has been successful with a minimum diameter of 10 µm. This way for example, a microLED die in the size of 30um by 50 or 80um can be supported. Furthermore, as shown in slide three, this technique also offers the possibility to control the thickness by printing several diameters. The smaller the bump diameter, the higher the aspect ratio. This are very nice results, showing the viability of gravure printing technique for microbumps. This technology can support current and near-term generations of microLEDs but will it evolve as microLED dies further shrink in the longer term? Join Komori and other members of the community to learn about all aspects of microLEDs from GaN microLED technology to transfer and tiling technology to bumping and color conversion technology and beyond. You can hear from the likes of Samsung, Sharp, Yole, ASMP, Coherent, Nanosys, CEA, AUO, Allos Semiconductor, KIMM, Luxnour, Omdia, Playnitride, micromac, and many many more www.TechBlick.com/microLEDs

A milestone or a watershed moment in the world of graphene commercial development took place this week: NanoXplore Inc. acquired the many of the assets of XG Sciences! NanoXplore has been a pioneer in commercialising graphene. Many know it for its ambitious activities in breaking down the cost and availability barrier of graphene by massively scaling up a well-engineered production process. This is a prerequisite for market development but is not sufficient. Another often-neglected prerequisite is overcoming regulatory hurdles before tonnes of the nano material in different continents can be sold! This is an essential yet arduous and expensive (!) undertaking . NanoXplore led the way here too, paving the way for itself and also possibly for other suppliers in the field. In this 5-min video- a throwback to a presentation by Nima Moghimian at TechBlick's Graphene and CNT event in 2021, you can learn about the steps that NanoXplore took to obtain regulatory approval and the results of their studies. Some of the results may be surprising to some, but it is worth remembering that graphene is often only a nanomaterial in one dimension. Also- lets not forget that carbon black- an old material with 18M tons of sales per year- is also a nanomaterials as 70% of carbon blacks posses a particle size <100nm To learn more visit www.TechBlick.com Congratulations to NanoXplore for yet another leapfront in this field #graphene #CNT #carbonblack #additives #graphite #Sianode #conductiveplastics #nanomaterials

In this article, we consider how to optimise a waveform to get better jetting, using a general dropwatcher approach that applies to many printheads. We will follow along step-by-step with a Dimatix Samba printhead to give example images and data along the way. Quick Reminder Of The Principles Let’s start by reviewing very briefly the principles of waveforms. In the schematic below, we show how a voltage pulse results in deformation of the actuator, creating pressure in the nozzle chamber and causing a drop to eject. What we are optimizing is the size, shape, and spacing of the pulses to ensure that the jetting matches our target requirements. Understanding Your Target The first step of any attempt to develop a waveform is to clearly define the goal. Usually, the most important targets to identify are the desired drop size, drop velocity, and jetting frequency. If you already know the target specifications, then you can get started straight away. If not, then you will have to do some investigation. If you are an ink company and have a specific machine to develop for, check with your customer what the usage conditions of the ink are. If your customer is an equipment manufacturer, they should be able to tell you all you need to know. If selling direct to user, then perhaps this information is not so easily available and you’ll have to work a bit harder to figure out what’s sensible. You can get an idea of the operating frequency from the carriage speed and the print resolution, remembering that if the print is multiple-pass this may be different from the final resolution. The Starting Point The very first step in waveform optimization is to establish a sensible baseline for our jetting so we can view it with the dropwatcher. If possible, an easy technique is to start with the printhead manufacturer-recommended, or default, single pulse waveform. As well as typical pulse timing, there will usually be some kind of calibration voltage (sometime called “label” voltage). Use this to start with as it should produce reasonable jetting. For our Dimatix Samba example, we are going to start with a waveform from the printhead user manual: a 26V amplitude pulse with a pulse width of 2.18us (including a 40V/us rise time). The next step is to get the drops visible in the field of view of the drop watcher. It is important that you can see the faceplate if possible; it helps a lot when it comes to understanding failures if you have any. The image below gives an ideal view for the Dimatix Samba printhead. If you are just doing a preliminary test with a syringe fill, then it is useful to minimize the ink consumption during testing. Jetting about 10-20 nozzles along the same printhead row at a moderate frequency like 8kHz will allow you to test for a while without having to refill the fluid. Do a quick measurement of the drop velocity to ensure that it is reasonable, maybe 5-6 m/s. Even if your eventual target is higher, this setting will usually allow easy measurements without too many satellites. If you find that the velocity is too low, you’ll want to increase the voltage of the pulse slightly, and vice versa. Our velocity happened to be acceptable without having to make modifications to the waveform, so 26V is an appropriate setting. Step 1: Optimizing Pulse Width The first step in waveform optimization is to get the basic pulse shape to match the acoustics of the head and fluid combination. In waveform terminology, we will begin by determining the proper pulse width. Because both the size of the nozzle and the fluid properties are fixed, we are looking for the amount of time to keep the nozzle chamber expanded that allows ink to move back and forth within it at a good rhythm. In general, there is a near-quadratic relationship between pulse width and drop volume and velocity. The optimal pulse width is the one that will produce the highest drop volume and velocity, so finding that peak is what our first objective will be. Determine what the current pulse width is for your starting waveform, and plan to adjust the pulse width from 50% below to 50% above that recommended setting. At each pulse width, measure the drop volume and velocity at a consistent distance from the printhead. Choose a step size to give a few data points so you can build a curve. For our Samba printhead, we are going to automatically sweep through pulse widths from 1.1us to 3.3us in 0.1us increments. By capturing an image at each value (using double pulse) we are able to quickly judge the speed of the drop visually and can supplement with measurements if needed. The image below is generated using a combination of JetXpert Add-Ons, XSweep and Stitch. The top of the velocity curve is where the timing of the pulse gives the most efficient drop ejection for your combination of ink, head, and electronics. Sometimes it is desirable to use a pulse width a bit higher than the peak since it can help with satellites. Getting some experience will help you make this decision. Once you have selected your pulse width, program that value into your waveform and let’s continue forward. Based on our image, we can see that pulse widths of 2.1-2.2us seem to produce the highest drop velocity. We can tell because each slice of the image was taken at the same moment in time, and the drop has travelled furthest from the printhead in these slices. If you recall, 2.18us was our starting pulse width from the Dimatix Samba manual, and indeed it seems to be optimal. Good job Dimatix! Saving Time As with most things in inkjet, it is up to the user to determine the level of precision to approach this process with. In the case of waveform optimization, choosing a smaller step size to test each parameter will be able to give you a more precise results. However, when doing this analysis manually, a smaller step size increases the time it takes to do this testing. To make the process faster, ImageXpert has a tool called XSweep, which will automatically adjust the waveform settings and perform the measurements for you. Step 2: Optimizing Voltage Now that we know we’ve got the timing right, we can explore the connection between voltage and drop volume and velocity. Usually, there is a linear relationship between voltage and drop volume and velocity, up to a limit. The normal trade-off is that increased voltage also produces increased ligaments, so the objective is getting the highest possible velocity that produces a nice clean drop without a tail that breaks into satellites. As we did before with pulse width, let’s try a range of voltages and measure the drop velocity at each one. It is important to also keep an eye on the drop volume and satellite formation, as this will impact our decision. Our goal at this point is to determine the voltage setting that gives us our target volume and velocity without too many satellites. With our Samba, we are going to automatically sweep through voltages of 21V-31V in 0.5V increments. The output is shown below. Once again, the results seem to match the theory. The drop velocity increases linearly with voltage, up to a point where satellites are introduced. Let’s choose a voltage a bit lower than the one that produced satellites and perform a measurement. We now know the drop volume and velocity that a waveform using these settings will produce and can compare it to our targets. However, our job is not done yet. Step 3: Pushing The Head A Bit Harder Now that you’ve improved your pulse and it’s producing the velocity you’ve been looking for, it is time to push the head a bit harder and turn up the frequency. This will test whether the waveform we’ve built so far performs well at our target frequency, as well as if there are any particular spots to avoid. If you already know what your key target frequency is, then you can save some time by just looking at jetting there, but don’t forget to include the subharmonics too. This ensures that if the drop spacing gets adjusted during rendering and printing the image, your waveform will still perform well. We think it’s usually best to do as much as you can to understand the entire frequency space. You already have the system set up, and you never know when a customer will ask to use that ink at another frequency. In addition to XSweep, Imagexpert supplies the Frequency Sweep Add-on to help speed up the process. This will automatically sweep through a range of frequencies and collect the data, which is especially helpful for higher frequency printheads. The image below is our Samba waveform jetting at 1 – 30kHz in 1 kHz steps. Fortunately, our drop formation looks pretty good across this range. Here is another example that tells a different story. Notice how the jetting is a consistent velocity up until about 19 kHz, then the velocity spikes? In addition to the increased velocity, we also see increased ligament length and satellite formation. This is resonance. At 19 – 24 kHz, the timing between the waveform pulses is such that the pulse is amplified by lingering momentum in the nozzle from pulse before it. With this knowledge, you can modify the design of your system to either avoid that frequency or use a different waveform for that range. What If The Results Are Not Good? If the waveform you created does not perform well at the target frequencies, choose a lower voltage and try again. It is an iterative process, where you might need to make small changes to pulse width and voltage and repeat in order to get the results you want. This is where automation comes in handy. If you just can’t seem to get your drop volume or velocity high enough, multi-pulsing might be able to help. Step 4: Introducing Multi-Pulsing When more than one pulse is used in the waveform to create drops then we call it multi-pulsing. This is not to be confused with grayscale; we are still only producing one drop size, we are just using multiple waveform pulses to do it. Multi-pulsing can be useful for increasing the volume of the jetted drops if a single pulse is not capable of ejecting enough ink. If we are going to use multiple pulses to create larger drops, we must begin by understanding the underlying timing of the ink moving in the head. We do this by creating two identical pulses and looking to see what happens to the ejection as function of the gap between them, as shown below. When the timing is right, the momentum of the ink in the nozzle will be increased by the second pulse, and we will see a faster drop once it is jetted. Let’s duplicate the optimized pulse that we created from before and adjust the spacing between these two pulses, analysing the jetting at each step. A good starting point is to vary the spacing from the minimum allowable value to double the pulse width of each pulse. The best measurement to do is to look at the velocity of the second drop that comes out (if it does at all) since the speed of that drop is very sensitive to pressure fluctuation caused by the first pulse. At low pulse gaps in some head/ink combinations, the drops are likely to have merged before you get the chance to measure them, whilst in others the second ejection might appear as a bulge travelling up the ligament of the first. What is important is to find at what spacing the drop(s) you can measure go fastest. The peaks in the behaviour are where the head resonance lies. Most successful greyscale waveforms work on or near the resonance period so that the ejection is optimised for a given amount of input. When we duplicated our optimized Samba pulse and swept the pulse spacing from 1.4us to 3.2us in 0.1us steps, we produced the following image. It is pretty clear where the speed of the second drop is the highest, which is our resonant period. Now that we know our resonant period we can build a waveform that uses it. The only thing to remember is that if you are going to stack pulses like this one after another, it is important to consider the voltage amplitude or you’ll push that final ejection velocity very high, which usually is a bad thing for nozzle wetting and satellites. So, with that in mind, you may start with something like this to get your target drop size. Making Multi-Pulsing Do Greyscale As we mentioned already, the key difference with grayscale is having the ability to vary drop size at each pixel on the printed image. This means you need to choose which waveform pulses to use for each gray level to get the desired drop size. The first step to achieving this is to break the waveform into segments that can be selected by the print controller. You then must associate the right segments to the grey levels. Just like the pulse shapes themselves, this part is very dependent on your system, and especially the software that allows you to edit the waveform “shape”. The easiest way to visualise this, and thus often used in patents on the subject, is to picture the waveform with separators and then have a table telling you which is used in each level. We have drawn this below for a single 5-pulse example. The reason we chose 5-pulse for 3 levels because it demonstrates nicely the high degree of flexibility that is possible, including the fact that pulse do not have to be identical or be linear in amplitude (like our first examples). The one thing to keep in mind is that the maximum frequency that can be used will be the inverse of the time taken to complete the whole waveform, regardless of which grey level you are selecting. Usually there are rules associated to how close pulses can be to each other to allow time for the electronics board to switch between the waveform segments. Most good waveform editors will tell you if there’s a going to be a problem. Now you can tune the individual pulse widths, voltages, and pulse spacings of the waveform segments to get the drop volume and velocity to match your targets. It is useful to have an image that places drops of different sizes next to each other in the same field of view, so you can study the impact of a change on all of the gray levels. This image shows three different gray levels in one field of view. Advanced Waveform Design The multi-pulsing approach can also be useful for controlling nozzle plate wetting, or influencing ligament break-off, for example. Extra pulses can come before or after the main ejection pulse as shown below. Tips for implementing more advanced waveform tricks are hard to systematize but we wanted to make sure you know these things are possible. There is another method that is used by some head manufacturers as standard, called bi-polar pulsing. The terminology comes from heads that use both positive and negative amplifiers to drive the PZT in both directions. The advantage of such systems can be getting a more efficient drop ejection from a lower overall voltage, but it also allows pulses to be programmed in any direction for manipulating the pressure variation following ejection. Since bi-polar capability makes the electronics more complicated, the effect can be recreated using a uni-polar circuit (positive or negative voltage only) that uses a rest voltage that is non-zero. We try to explain the difference with the image below, which is taken from a couple of recent patents from two main head manufacturers. The image on the left is a bi-polar waveform, the image on the right is a uni-polar with a non-zero rest voltage. In both cases the waveforms are more than a succession of simple trapezoids like we described before. Generating the more arbitrary shapes needs a different approach than just how tall and wide the pulse will be. Usually the waveform is now defined by segments changing from one voltage to another over a given time. Some specific electronics are required and this can be vendor specific. Optimizing waveforms using these techniques may be elaborated on in a future article.

This would be a major step towards industrialization. Here, we discuss the transition from 2-step printing to one step printing with antisolvent to one-step printing with no antisolvents. Riikka Suhonen et al discussed the latest developments at TechBlick's event in Dec 2022. Here is a summary 2-step approach: In general, most approaches are based on a 2-step printing in which the lead iodide (from PbI2-DMSO ink) is first gravure printed on a printed SnO2 NPs layer and then dried. The DSMO is then washed away in a water and isopropanol path and the remaining porous layer is dipped into a chemical second path to form MAPbl3. The 'pilot' R2R runs yield PCE of 9.7%. This approach requires two chemical steps, slowing the process. Furthermore, handling the porous Pbl3 layer is difficult in R2R environment and oncersion to FA- or FACs-perovskite challenging 1 step printing + antisolvet: the standard antisolvent is ether but this can not be printed due to high volatility. Therefore, there has been huge effort in developing an antisolvent which could be printed industrially and was environmentally friendly. VTT et al developed the tBuOH:EA system. This way they achieved fully R2R gravure printed perovskites with efficiency of 13.8%. This is an elegant solution. Nonetheless, There is a desire to eliminate the antisolvent step as it will require a spray or bath step together with solvent fumes. 1 step printing: Here they used starch as a rheology modifier with perovskite precursor, forming a viscous ink which can be used to print well-defined patterns. In this R2R 'lab' printing starch-based MAPb3I inks they used IR annealing and hot air annealing. The first lab runs showcased a champion result of PCE 9.9%. This is still an early stage development but shows that reasonble efficiencies can be achieved using R2R gravure printing with only a single step! Of course- these results are early stage. Lifetime remains an issue and development area. Nonetheless, this is an important field to watch further We will soon announce the agenda for our 2022 edition of TechBlick's event on organic, perovskite, and tandem photovoltaics Riikka Suhonen Antti Kemppainen Ari Alastalo Jani-Mikael Kuusisto Thomas Kraft Henrik Sandberg #perovskite #photovoltaics #gravure #R2R #flexible #futureofPV #solarcell

The dielectric material is often the bottleneck against fully printed high-performance RF and MW devices. This is often a neglected challenge as the emphasis is mainly on the conductive layer. Indeed, the development of a suitable low-loss digitally-printable dielectric material with high and controlld resolution is a technical challenge. In this 3-min video, Yuri Piro from University of Massachusetts Lowell explains why this is challenging Yuri said " So photo polymers are the go to materials and the very common conventional polymers are typically acrylate or methacrylate. Those are initiated with radicals and they have huge dipoles. And those dipoles are actually very important for the kinetics of the reaction. They stabilize the radical during propagation and if you were to start to remove those dipoles to make your material less lossy, you would destroy the kinetics of the reaction. You couldn't form this polymers on the spot. Now Cationic polymerization is also very common for things like Epoxies, but again you have the electron withdrawing groups to stabilize the cation propagation and removing those again really hurt your kinetics. So there's a couple of ways around that. One of the ways is you use pre-formed non-polar materials and you just dissolve them in some sort of solvent. There's two big issues with that approach. The first issue is you have to drive off the solvent during curing, and that introduces a lot of stress into the film. And the other issue is the viscosity. Typically, those are high risk materials. And to get the viscosity down to where you can use high resolution printing, you need to use large fractions of solvent. And a lot of the solvents to get the non-polar materials dissolve have to be things like Taliban or xylene. And those are pretty toxic and hard to use in manufacturing environment. So there's this big need to use to make non-polar polymers on the spot that have this low dielectric constant and minimal processing conditions. Now, there are some solutions happening right now. You'll see in printed electronics the POLYAMIDE is a common material people use that has a low CTE and has a pretty low dissipation factor. But one of the issues with Polyimide is the material has to be immunizes on the spot. So you have to heat up your material past 180 degrees. And once you start doing that, you have to disqualify some of the flexible materials that are kind of the most exciting parts of integrating print electronics in the first place. Another common material people use is benzos butane. But again, that requires processing conditions that are very long and hot and destroy the ability to introduce flexible materials. So coming up with a non-polar material that you can form on the spot with low processing conditions and low polarity is difficult and you really can't use these conventional approaches."