Andrew Stemmerman & John Yundt SunRay Scientific Inc. Eatontown, NJ USA andrew@sunrayscientific.com johny@sunrayscientific.com SunRay Scientific of Eatontown, NJ, USA has developed a new and innovative approach to electronic component assembly. This article will outline the developments of this technology and show examples of this magnetically aligned Anisotropic Conductive Epoxy packaging method used on various substrates. Progress will be shared for dense and fine pitch Land Grid Arrays (LGA) on a semi-rigid interposer. Introduction Flip-chip die and die-to-die bonding, from dense to fine pitch, typically require solder balls and underfills. Underfill and/or edge encapsulant is often utilized to provide additional mechanical strength and stress reduction. The result is a complex assembly process flow. Localized placement of Anisotropic Conductive Adhesive (ACA) or Anisotropic Conductive Film (ACF) for specific components typically involves the fine-pitchuse of thermocompression bonding, an additional process step that could also be damaging to thin silicon. Another drawback for traditional interconnect materials is relatively slow processes, limiting the utility of such technologies. Development towards a wafer scale compatible packaging method will be shared, using a pressure-less and low-temperature magnetically aligned Anisotropic Conductive Epoxy (ACE). Figure 1. Flip Chip assembly comparisons: traditional solder balls & underfill attachment (Left); Die attach with z-axis magnetically aligned conductive epoxy (Right) A summary of the novel approach is shown above in Figure 1. First, ferro-magnetic particles dispersed within an epoxy are coated onto a substrate. The ferro-magnetic particles form z-axis magnetically aligned columns, fixed in place during the die-to-substrate cure process without any pressure applied. The formation of the columns during the curing process is illustrated in Figure 2. This technology simplifies the assembly process to a single adhesive application, which provides both electrical interconnection and mechanical reinforcement. No additional underfill material is needed. Fine patterning is not required as the entire area of the component target location is deposited with epoxy. The device alignment process is more forgiving relative to solder ball-to-solder pad alignment. Z-axis columns align after component placement, magnetic pallet exposure and cure is achieved. Figure 2. X-Ray photos of Z-axis magnetically aligned particles ferromagnetic in an Anisotropic Conductive Epoxy (ACE) Thermal or UV curing methods complete the component attachment without any thermocompression (cure method is epoxy formulation dependent). Thermal curing occurs within the 80°C to 160°C temperature range. This article outlines the developments of this technology and shows examples of this magnetically aligned Anisotropic Conductive Epoxy packaging method used on various substrates. Progress will be shared for dense and fine-pitch Land Grid Arrays (LGA) on a semi-rigid interposer. Additionally, advancements made for die-to-die bonding will be presented as well as updates towards achieving ≤ 60-micron pitch. Other proposed direct die-attach packaging concepts will be illustrated. Example #2 covers development work performed on attaching a 126-pin Land Grid Array (LGA) bare die to a polymer semi-rigid multi-layer substrate. The use of the substrate resulted in multiple challenges for bare die attach. The non-planarity of the conductive circuit pads was one issue. The electrical resistance variation between pads had to be minimized for optimum performance. The non-uniformity of the substrate’s conductor pads is evident in the photo on the left. The schematic on the right illustrates how the ACE material allows for “leveling” in connecting the bare die to the non-planar substrate. Figure 3. 126-pad semi-rigid substrate (Left) and illustration of bond between die and substrate Additional learning during this work was in identifying trapped moisture within the polymer-based substrate as a cause for voids in the ACE during cure. These bubbles not only prevented connection in some cases but interfered with proper z-axis column formation. Prebake for the substrate was added as a step for this particular type of assembly. Two formulations were the focus of the work in Example #3. These were the Fine particles ACE and the Ultra Fine particles version. Stencil thicknesses of 0.001” to 0.005” were studied, as this tool has the most impact on establishing bond line thickness. The target for choosing the best formulation, tool and bond line thickness was lowest average resistance values with lowest deviation among the 126 pads. Iterative testing was done. “Heat maps” based on the 126 pad locations were created to visually observe resistance values within set target and acceptance ranges. The next two Figures show results from early work on process development with each epoxy formulation and stencil tools, to the progress made with the final choices on material and stencil thickness. Ultimately the Ultra Fine particles ACE with a 0.001” thick stencil was chosen for this LGA-to-substrate assembly application. Summary Table 1 shows the results of the chosen ACE and stencil, and Figure 6 is a cross-section from the development study. Figure 4. Pad-by-pad resistance measurement studies, early iteration (Left: Ultrafine, Right: Fine) Figure 5. Pad-by-pad resistance measurement studies, final iteration (Left: Ultrafine, Right: Fine) Table 1. Summary of performance metrics (continuity, resistance & deviation, pad-to-pad) Figure 6. Cross-section of component attached and electrically connected with the Z-axis ACE (Photo courtesy of Rochester Institute of Technology) Example #2 takes the LGA and Substrate subassembly to the next level, a large area 8” x 10” circuit board populated with four of the subassemblies plus components of various sizes and function. This larger assembly involves attaching all the multiple components and subassemblies in one ACE attachment process. Passives range in size from as small as 0201 up to 2220. Other devices are a 26-pin SMT connector and SoICs. This project is underway, and results will be shown by SunRay at TechBlick live in October. Fine-pitch die-to-die bonding with the ACE is the third example. The development methodology is like the other projects. An initial focus was on measuring continuity and resistance at pad sites as part of identifying the optimum process parameters and stencil tool for this application. The degree of difficulty is greater with finer pitch. Dense arrays of 60 microns pitch die, with 30 microns pads and 30 microns spacing, were used. Join the FREE-TO-ATTEND Winter Festival to Hear About the Latest Innovations Spaces are LIMITED on a first come first served basis A Design of Experiments (DoE) was established for the stencil studies. Laser profilometry was used for 3D and 2D scans of the two surfaces to be bonded, as was employed for observing the non-planarity of the semi-rigid board in Example #1. All initial steps were done manually: hand stencil printing, die placement with die bonder, batch oven cure and electrical probing. Prior to using fully functional devices, Quartz substrates patterned with the top layer of each die in the bond pair, were procured and used in early studies. The purpose was to provide enhanced analysis of the bonded die pair before, during, and after bonding/curing has occurred. Bond parameters were observed at each step of the process: pre-bond, bond, and post alignment & cure. Figure 7. Left: Target overlay of quartz substrates; Middle: ACE deposit before bond; Right: Post-bond, before z-axis alignment and cure Due to the finer pitch requirements, the test vehicles have a nickel layer applied during wafer fabrication, at the bond pad locations. Past experimentation, as pictured in Figure 8, has shown nickel application may lower the resistance of the bonded circuit by directing column formation to the metallized bond pad boundary, the nickel pads, acting as localized magnets, attract column formation during exposure to the magnetic pallet. This only applies to the bond pads themselves, to concentrate the ferromagneticmetalized particles within the ACE more towards the connection points. This creates a higher density of columns within each pad. Figure 8. Left: No nickel interlayer and ACE; Right: ACE after cure with Nickel interlayer layer in pads Conclusion Besides the addition of the nickel layer to the functional die, key parameter targets were updated for the project’s next phase. In the short-term alignment, fiducials on the quartz plates were updated to improve bonding in X, Y, and theta; and the size of test probe pads were increased to improve accuracy and reduce testing time. The development efforts for all three examples are still underway. The conclusions thus far are: Successful demonstrations of Heterogenous Packaging using z-axis magnetically aligned epoxy for structural & electrical bonding. Similar established process techniques and test methodologies are usable across applications, although each has unique requirements. The Ultra Fine particles ACE formulation has the best performance for finer pitches and more challenging alignments. Uniform bond lines between device pads are critical for optimum electrical performance. Excellent performance results were obtained, even with manual assembly techniques. Performance will improve with automation. In concept this z-axis magnetically aligned conductive epoxy approach could integrate multiple silicon wafers on top of each other, creating the possibility for an exceptionally dense integrated System-In-a-Package (SIP). Processing temperatures can be as low as 80°C, opening room for alternate substrates and biocompatible assemblies. This anisotropic epoxy is not limited to specific device attachment; it can be used to bond multiple component sizes and styles across an entire substrate. 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Recent advances in Additive Manufacturing (or 2D and 3D Print) have poised many of these technologies to displace or augment traditional electronics manufacturing methods, yet significant further advances are still needed in order to obtain broad adoption for high-volume manufacturing of electronics devices. After presenting a view of how additive manufacturing methods could be leveraged for wearable AR/VR devices as well as highlighting the benefits of additive methods, I will dig into key areas where significant developments are still needed, including: component-level and device reliability; design tools; close-loop in-situ process monitoring; integrated manufacturing workflows; productivity and yield; and material properties. I will then conclude with a few application examples, highlighting unique solutions promised by additive methods as well as gaps which remain. SAVE THE DATE

Company: Syenta Speaker: Jekaterina Viktorova SAVE THE DATE

Brewer Science's vision is to design, build, and deploy connected gas and water sensors that monitor environmental contaminants quantitatively on a large scale. For the last 10 years, Brewer Science has developed the technology to print cost-effective sensors that can measure contaminants in water, such as heavy metals (lead, cadmium), copper, nitrate, pH, and ORP, as well as sensors that assess air quality by measuring gases like carbon monoxide, carbon dioxide, hydrogen, VOCs, and oxygen. Brewer Science fabricates a variety of printable sensor materials and deposits them onto a substrate utilizing processes such as physical vapor deposition (PVD) sputtering, screen printing, stencil printing, ink-jet printing, and high-speed jet dispensing. Producing low-cost sensors with low-power electronics and wireless communication will enable the deployment of sensors over vast areas for real-time monitoring of environmental conditions. SAVE THE DATE

The convergence of lab-based discoveries and industry-need created reimagined products based on stretchable and/or flexible substrates.Soft electronics made of silicone were translated into a printed technology to create smart bedding products to monitor aged-care residents and improve quality of care. Working closely with manufacturers, the evolution of the technology from stretchable electrodes to a sensor array across a mattress, will be covered. This approach represented a new take on production of electronic textiles.Combining flexible substrates with surface mount components, composite structures have created a category of modular sensing skin patches. Based on clinical need, different sensor combinations have been utilised for aged-care health monitoring, with potential use cases targeted to dementia care and post-operative management. SAVE THE DATE

IoTech is introducing a new and patented digital additive manufacturing technology: the Continuous Laser-Assisted Deposition or CLAD. CLAD is a breakthrough multi-material production process for electronics, from semiconductor packaging to flexible electronics. CLAD enables the fast, precise, high-resolution, and high-volume deposition of most industrial materials, no reformulation required. Manufacturers can - use their standard industrial materials, - control the deposition of every single drop, - print at up to 30µm resolution and, - reach unmatched production yields. The system is fast, contactless, high-resolution and micron-accurate. It enhances manufacturing flexibility for advanced electronic designs. CLAD enables more compact, powerful product functionalities in a wide range of applications. It is compatible with most conductive and dielectric fluids, even of high viscosity. CLAD is also ESG-compliant and labour-efficient. It provides an alternative to highly polluting subtractive technologies, enabling the re-shoring of production processes to OECD countries SAVE THE DATE

Name:Łukasz Kosior Company: XTPL XTPL provides additive manufacturing technology and conductive materials at the micron scale to address complex issues in the advanced electronics industry. The company has developed its own solutions that allow for extremely accurate printing of functional features at the micron level with high resolution. This capability extends to both planar and non-planar complex substrates, including the ability to print continuous and highly conductive interconnections oversteps. In our presentation, we will showcase the available solutions for next-generation Flexible Hybrid Electronics, Advanced IC Packaging, and Flat Panel Display applications. Additionally, we will present our plans to introduce Ultra-Precise Deposition technology to the industry. SAVE THE DATE

Speaker: Ashok Sridhar Company: TracXon Printed Electronics is experiencing a strong growth phase of late. To sustain this growth and to turn the hype into actual products in the market, it is necessary to come up with new business models that provide demonstrable value to companies that want to adopt Printed Electronics in their products. Such added value should go above and beyond product-related benefits such as flexibility, stretchability, conformity, etc. At TracXon, a Netherlands-based foundry for Printed Electronics, we offer unique business models that can aid broader penetration of Printed Electronics products, by lowering the barrier to entry for OEMs and Tier-1s across domains such as automotive, healthcare, IoT, consumer electronics, etc. SAVE THE DATE

Our research group at Yamagata University in Japan is actively developing flexible and printed organic electronics, covering all related technologies from materials and devices to fabrication processes and applications. Our focus is on wireless applications for healthcare, robotics, and logistics. We have recently developed highly sensitive and reliable pressure, strain, and humidity sensors using composite materials of carbon and polymeric materials with simple printing methods. The pressure sensor exhibited a high resistivity change with a sensitivity of 0.014kPa-1 when pressure was applied. The stretchable strain sensors demonstrated high sensitivity with a gauge factor of approximately 14 and could stretch up to 100% with small hysteresis. The developed humidity sensors exhibited a high resistive response of 120% over the relative humidity (RH) range of 30% to 90% through an absorption and desorption mechanism, with fast response and recovery times. We have used these sensors to demonstrate human pulse wave and respiration detection, as well as tactile sensing for robot grippers. In addition, we have established flexible hybrid electronics (FHE) with screen printing methods and combined these sensors with the FHE technology to realize more practical applications for the Internet of Things (IoT) society. SAVE THE DATE

Flexible printed circuit boards (FPCs) have found uses in a wide variety of applications, including health/wellness, mobile devices, aerospace and many more. Conventional FPCs consist of copper patterns formed on the surface of a flexible film using standard printed circuit board fabrication processes. Historically, polyimide resin (PI) has been widely used because it is readily available and possesses heat-resistant property which make it compatible with high volume assembly processes like solder reflow. However, new applications and device designs like wearables are driving the development of more conformable circuits. Stiff, high-modulus films such as polyimide are not suitable for these products and currently available pliable, low modulus films like thermoplastic polyurethane (TPU) are not compatible with surface mount assembly processes. Researchers at Panasonic Electronic Materials are developing a new material technology that overcomes the limitations of conventional FPCs. In this presentation, we will introduce our novel ultra-pliable circuit board material development. SAVE THE DATE

Thibaut Soulestin, PhD ; Lead Application Engineer at Henkel Printed Electronics; thibaut.soulestin@henkel.com Henkel Adhesive Technologies has developed a large material portfolio of conductive inks and coatings suitable for printed electronics technology. Our portfolio offers material solutions ideal for various smart surface technologies, including self-regulating foil heaters. Self- regulating foil heaters are enabled by Henkel’s Positive Temperature Coefficient (PTC) inks in combination with silver and dielectric inks. Understanding the origin of the PTC effect, typical characterizations, and basic design rules enable our customers to reveal the full potential of this technology. 1. Introduction to Henkel Positive Temperature Coefficient (PTC) carbon inks Different types of conductive polymer composites (CPC) exhibit positive temperature coefficient (PTC) properties. They have been extensively studied and some are commercially available. A vast majority is obtained by compounding a polymer binder with conductive fillers, mostly carbon-based. The increase in resistance of the conductive networks during heating is caused by the thermal expansion of the polymer and the change in the distance between the conductive fillers. The PTC effect usually occurs during the phase transition of the polymer matrix, the glass transition, or the melting. After the maximum PTC effect, if the temperature keeps rising, a negative temperature coefficient (NTC) effect can be observed due to the re-aggregation of the conductive particles. Join us at TechBlick's Future of Electronics RESHAPED conference & tradeshow in Berlin on 17-18 OCT 2023 - www.techblick.com/electronicsreshaped Contact thibaut.soulestin@henkel.com for your discounted passes Henkel carbon PTC inks are like other screen-printable carbon inks and are based on three main components: (I) carbon particles for the electrical conductivity, (ii) a polymer binder for the mechanical properties and adhesion to the substrate, and (iii) a solvent. The dry ink layer is then obtained after drying and solvent evaporation. Henkel developed a specific and patented technology using micronized wax particles to introduce the PTC effect. A fine wax powder is added as a fourth main component to the ink. The resistance will increase exponentially near the wax melting point, resulting in a high PTC ratio and a well-controlled self-regulation temperature. By finely controlling the melting point and the size of the wax particles, and thus the particles’ volume expansion, the PTC effect can be finely tuned to match customer requirements. Figure 1. Schematic graph representing the exponential increase of resistance of Henkel positive temperature coefficient (PTC) ink. At a defined temperature, the micronized wax particles (spherical white), nicely dispersed between the carbon particles (black ovals), increase in volume, pulling apart the conductive carbon particles, leading to the resistance increase. Table 1 overviews the commercially available and under-development Henkel PTC ink range. Low voltage inks are formulated to self-regulate at voltages below 50 V. High voltage inks, identified by HV in the name, can be used for voltages above 50 V. Low and high voltage inks differ mostly by their sheet resistance. A non-conductive ink, NCI, is also available for each self- regulation temperature, allowing the printer to adjust the sheet resistance. Table 1. Henkel PTC ink range. 2. Typical Example of 9V, 60 °C, self-regulating demo heater 2.1 Layout Figure 2 shows the exploded view for a typical PTC heater. The polyester substrate is an industry standard. A first layer of highly conductive silver ink tracks is printed, typically with LOCTITE ECI 1010. Two main areas can be identified: the busbars and the fingers. On the sides, the busbars carry the current and must be designed according to the maximum current peak to avoid local heating. The finer silver fingers give the interdigit structure and allow having all PTC elements in parallel. Then, the PTC ink, from LOCTITE ECI 8000 series is printed on top of the silver tracks as numerous independent elements. On top of the conductive inks, an insulating layer is mandatory. This layer can either be a printable dielectric or a laminated foil. As PTC inks are living materials with a variable resistance, the influence of the insulating layer should be closely monitored. It should not deteriorate the ink properties, such as PTC ratio and long-term reliability. Figure 2. Exploded view of 9 V demo heater showcasing the four main components. For this 9 V self-regulating demo heater, substrate is PET 125 µm, silver ink is LOCTITE ECI 1010, PTC ink is LOCTITE ECI 8001 with self- regulation in the 55-60 °C range, and translucent dielectric UV-curing ink is LOCTITE EDAG PF-455BC. 2.2 Typical Voltage Sweep Characterization Voltage sweep curves are characteristic of one self-regulation in a specific condition. Taping a heater on different surfaces, like a metallic plate or a foam, will give different results. For characterization purposes, it is interesting to characterize the heater on an insulating foam to expose potential limitations like hotspots or printing inhomogeneities. Figure 3 shows the resistance and average surface temperature change with increasing applied voltage. Three typical zones of a self-regulating PTC heater are nicely exemplified. Zone I, Heating-Up. Temperature increases with the increasing voltage thanks to the Joule effect until reaching the onset of self-regulation. Zone II, Self-regulation. With the increasing voltage, resistance increases thanks to the volume expansion of the wax particles. Zone III, Overruled PTC effect. The voltage is too high. The resistance cannot increase anymore. Temperature rises above the self-regulation, reaching the melting point of the wax. Melting of the wax brings the carbon particles closer and the resistance drop. Runaway may occur. Applying 5, 8, or 10 V to the heater will give the same self-regulation temperature based on this voltage sweep. This is due to the sharp PTC effect around 60 °C. The higher the PTC ratio, the larger the self-regulation plateau. High PTC ratio of Henkel inks enables rapid heating than to high initial power. Figure 3. Typical characterization curve of a self-regulating PTC heater. Temperature (grey curve) and resistance (red curve) are measured as a function of increasing voltage. 3. Heater Initial Guidelines 3.1 Requirement Definition To start your self-regulating PTC heater project, you must have some crucial primary information: The driving voltage that will power your heater. It will be closely related to the spacing between two silver fingers and the resistance of one PTC unit. The higher the voltage, the higher should be the resistance of the PTC unit. It is possible either by increasing the distance between the silver fingers or increasing the sheet resistance of the PTC ink. The initial heating power. To heat an object, you need a heat source with a higher temperature than the object and sufficient power to heat this object. If you have a low power hot heater, then the object will heat-up very slowly. Conversely, you may overrule the PTC effect if your heater is too powerful. Knowing the driving voltage and the initial heating power will allow the calculation of the resistance of the heater, 𝑅 = 𝑈2⁄𝑃. Voltage and resistance define the initial in-rush current 𝐼 = 𝑈⁄𝑅. Silver busbars must be designed according to the in-rush current. The self-regulation temperature to choose the adapted PTC ink. The heater dimension or available area. It will also be important to identify the heater integration and heat diffusion behavior early in the project as it strongly impacts the heater design and layout. 3.2 Basic Design Rules and Calculations 4 Accelerating Customer On-Boarding Developing self-regulating heaters requires a large range of expertise such as material, printing, circuit design, heat transfer, and integration. Following a methodology based on years of feedback enables a progressive learning curve and the identification of key parameters. Figure 4 gives an overview of this methodology. If specific expertise is needed, Henkel team can bring external partners to the table for the success of customer projects. Figure 4. Overview of Henkel PTC ink on-boarding methodology Join us at TechBlick's Future of Electronics RESHAPED conference & tradeshow in Berlin on 17-18 OCT 2023 - www.techblick.com/electronicsreshaped Contact thibaut.soulestin@henkel.com for your discounted passes

By Thomas Kolbusch, Director of Sales, Marketing, and Technology, VP 1. Abstract The Roll-to-Roll (R2R) processing methodology, pivotal in the fabrication of printed electronics, particularly 3rd Gen photovoltaics (OPVs), offers significant advantages. Yet, inherent technical challenges pose constraints in achieving optimal device performance. This article delves into the mechanics, advantages, and impediments associated with the R2R method as applied to OPVs. 2. R2R Process: Operational Mechanics and Implications 2.1. Mechanism At its core, R2R involves unreeling a flexible substrate from a source, subjecting it to various fabrication processes, and subsequently reeling the treated substrate. These processes can encompass material deposition, lithographic patterning, and post-fabrication treatments. 2.2. Benefits High Throughput: Continuous production translates to faster manufacturing cycles. Economic Viability: Economies of scale achieved reduce per-unit costs. Versatility: It enables the creation of lightweight, flexible electronic devices. 3. Inherent Technical Challenges in R2R Processing for OPVs 3.1. Ensuring Quality Homogeneity Attaining uniformity in deposition across vast substrate lengths poses a formidable challenge. Factors like deposition rate, substrate tension, and ambient temperature can influence the end product's quality. 3.2. Addressing Material Limitations For OPVs, the choice of materials is critical. Many organic materials used in these cells are sensitive to environmental factors like humidity and temperature. The R2R process, being continuous, requires that these materials remain stable over extended periods, a challenge that is currently under intensive research 3.3. Guaranteeing Consistent Device Performance Securing uniform device efficiency across an extended substrate requires rigorous quality control. Discrepancies in layer composition or thickness can culminate in efficiency variations, detracting from the overall process yield. 4. An Analysis of Two Decades of OPV Advancements Over the preceding 20 years, significant strides have been made in OPV technology: Material Evolution: Introduction of novel organic compounds to enhance light absorption and electron mobility. Architectural Refinements: Tandem structures, where multiple OPV layers are stacked, have emerged to enhance the cell's absorption spectrum Optimization of R2R Processes: Advancements in substrate control, improved coating and printing techniques, and swifter post-deposition treatments have been established. Despite these advancements, the conversion efficiency of R2R-produced OPVs remains an area of ongoing research when compared to other photovoltaic technologies. 5. Summary The potential of the R2R process in reshaping printed electronics production is clear. However, its broader adoption, especially for OPVs, demands a precise understanding of its challenges and a continuous drive for research and innovation. The advancements over the past 20 years underline the ongoing effort in this field and the need for further refinement to fully exploit R2R's benefits in OPV manufacturing. Coatema is working on all of these topics with cooperation partners in R&D and industry and with the Horizon Europe project Flex2Energy will establish a production line for OPV in Greece with integrated module assembly. This will be a boost to the European efforts to be more independent from imports from China. The growth rate of the global OPV market