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 microLE...

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 #condu...

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, ...

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 th...

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 ...

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 precurso...

Speaker: John Skabardonis | Company: Covestro| Date: 10-11 March 2021 | Full Presentation Driven by the desire for ever more compact and sophisticated devices, increasing demands for improved functionality and for more customization options, OEMs are turning to functional integration. Thin, three-dimensional parts which were previously simply thought of as covers, or “skins” can now incorporate diverse functionality. This presentation will explore different means of achieving the above goals through the use of materials from Covestro. John Skabardonis High-Tech Materials for Electronics @ Covestro Bio John Skabardonis is a Chemist-turned-Marketer-Communicator in the Polycarbonates business unit at Covestro, LLC. He is responsible for technical marketing for electronics, electrical and appliances in the Americas region. John is fascinated by the rapid evolution of technology and is focused on materials and techniques which enable this evolution. He is also intensely interested in social media as a means of helping make information easily accessible. John received a Ph.D. in Physical/Organic Chemistry from Case Western Reserve University. He is a design advocate & a member of the Industrial Designers Society of America, a Distinguished Toastmaster and a chairholder in the Color Marketing Group. 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 m...

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. 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 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 approaches is an alternative to the standard silicon interpose technology. Next was the development of Foveros platform, allowing face-to-face integration of dies from different foundries onto a package all connected via silicon base logic die. As you can see, these technology will involve 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 pitc here is limited to around >120um. Next, the 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 technolog...