Reflow soldering furnace used on mounted PCB

This article provides a detailed overview of the solder reflow process, types of reflow ovens, temperature profiles, solder paste composition and selection, reflow process potential challenges, solutions, inspection, and quality control techniques. 

Solder Reflow: An In-Depth Guide to the Process and Techniques

<p id="isPasted">Flexible and printed electronics have significantly evolved in the last few decades, bringing several advantages for multiple industries, such as biomedical, automotive, satellites, and more.</p><p>Flexible electronics refers to a class of lightweight printed circuit boards that can be bent, rolled, or even folded without losing functionality. It covers electronic components and devices built on stretchable substrates that can be used in applications such as displays and sensors.&nbsp;</p><p>Printed electronics are manufactured by processing combinations of thin layers of functional material (ink) on a low-cost substrate that can be recycled or degraded naturally. This technology has the potential to lead the electronics industry toward e-waste minimization.</p><p>Considering the benefits of flexible and printed electronics for different industries, this article explores the current state of these technologies, recent breakthroughs and trends that we can expect to reach the market in the next few years.</p><h1>Flexible and Printed Electronics Applications</h1><p>Flexible and printed electronics production is based on industrial techniques such as flexography or screen printing. Printed electronics already enable the production of flexible keyboards, adaptive antennas, interactive books and posters, electronic skin patches, sensors, and more. The printed electronics field has made significant advances, particularly in Radio Frequency Identification (RFID) and sensing labels, contributing to a new solution in smart packaging.</p><p><span style="background-color: transparent;">The growth of IoT applications has increased the demand for lightweight and cost-effective technologies that can securely detect, store, and transmit information. Flexible electronics is an ideal solution to fill this gap and satisfy the requirements of these applications.</span></p><h1>Latest cutting-edge technology in Flexible and Printed Electronics</h1><p>Regarding advances in flexible and printed electronics in recent years, printing processes and materials have made significant progress.&nbsp;</p><h2>Processes</h2><p>In terms of printing processes, various methods have been used for printed electronics. However, two techniques stand out and have been the main approaches to printing: contact printing and non-contact printing.</p><p>In contact-based printing technology, however, structures printed with ink are brought into physical contact with the substrate. Gravure printing, gravure offset, flexography, and roll-to-roll (R2R) printing compose contact printing technologies. Significant progress has occurred in some contact techniques, such as R2R.</p><p>In non-contact printing, the solution is dispensed through openings, and structures are defined by moving the substrate support in a pre-programmed pattern. The main non-contact printing techniques include screen printing, slot coating, and inkjet printing. These techniques have received more attention because they are simple, affordable, fast, and adaptable to manufacturing.</p><h2>Materials</h2><p>The most promising alternative materials for flexible electronics are organic materials and oxides. Particularly, combining organic and inorganic materials with printing technologies enables the creation of thin, lightweight, environmentally friendly, and economical electronic systems.&nbsp;</p><p>New inks also are needed to advance printed electronics, making it possible to achieve higher electron mobility thin-film transistors (TFTs) with greater uniformity and reliability. TFTs require downscaled electrodes to achieve a high enough switching frequency for wireless communication applications. The downsizing of TFTs is a beneficial factor in flexible and printed electronics applications.</p><p><span class="fr-img-caption fr-fic fr-dib" style="width: 302px;"><span class="fr-img-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1683794181800-flex+table.png" style="width: 300px;" class="fr-fic fr-dib"><span class="fr-inner" spellcheck="false">Evolution of the reduction of printed TFT channel length for several printing methods. Image credit: [5]</span></span></span></p><p>Another aspect is the improved sensitivity of printed sensors achieved through downscaling, such as using interdigitated electrodes. These are manufactured by combining two separately addressable electrode arrays.</p><h1>Trends and challenges&nbsp;</h1><p>Despite the significant advances made by oxide-based devices and organic materials, research is still needed to improve the electrical characteristics and increase electron mobility and threshold voltage stability. In addition, reducing the bias and instability of the light voltage are points to be improved to increase the quality of flexible electronic systems.</p><p>Applications such as organic light-emitting diodes (OLEDs) and organic photovoltaic diodes (OPV) have already reached a certain level of maturity. However, stability is still a challenge to overcome using them for printing on flexible substrates. Flexible OLEDs have shown promise for display and lighting applications in smartphones. However, there still are issues regarding the materials used, such as low-intensity blue-light fluorescent materials, because high-intensity materials have a reduced lifetime. TFT metal oxide drives OLED displays, but election mobility and photoelectric stability improvements are needed. A possible solution could be doped oxide TFTs. One of the challenges in TFTs is the instability of gate bias voltage and low electron mobility, affecting product efficiency. Silver or other metal-based inks look promising for improving the mobility of these transistors.</p><p>Regarding OPVs, it is a proven, stable technology that can operate for tens of thousands of solar hours if protected from damaging oxygen and humidity. It has good stability and low printing cost. However, one of the problems with the technology is that it has a lower efficiency than conventional solar modules. Therefore, it requires further development for OPVs to achieve commercial maturity to be widely used.</p><p>IoT can also benefit significantly from flexible, printed electronics. However, to get the most out of it, new energy storage systems are necessary to meet the demand for such applications. Therefore, improved inks and substrates are essential for these technologies&#39; scalability.</p><h1>What we should expect for the next 5 years</h1><p><span style='background-color: transparent; color: rgb(66, 66, 66); font-family: "PT Serif", serif; font-size: 19px;'>Roll-to-roll (R2R) has the high potential to enable the development of inexpensive, wearable, large-area electronic devices in the coming years. Once the desired improvements are achieved, this technology will be a promising trend for the coming years.&nbsp;</span></p><p>Similar to R2R, 3D printing of flexible electronic systems is also a trend for the coming years. 3D-printed electronics allow complete circuits to be integrated into an object. It will enable the production of wearable electronics, bioelectronics, and personalized healthcare systems. In addition, flexible electronics can integrate electronics and technology to create interactive and functional clothing or accessories by immersing textile electronics.</p><p>Flexible and printed electronics are not only prominent in the areas of technology but also in the field of healthcare. Flexible electronic medical devices for remote patient monitoring can be more convenient and comfortable. Tracking vital biometric parameters such as heart rate, movement, and temperature would facilitate digital health.&nbsp;</p><p>Following the trends, the use of flexible and printed electronics in modernizing automotive products is present in manufacturers&#39; innovation. Examples include thin-film heaters, flexible backlighting, and capacitive touch surfaces. In addition, it helps improve connection to telecommunications infrastructure through transparent antennas, which is crucial to the concept of the connected car.</p><p>Finally, flexible electronics support Industry 4.0. The main focus is on increasingly adopted factory sensors to monitor products and production processes. 3D electronics help sensors adapt to the existing production infrastructure and reduce costs. Vibration and temperature sensors can be fitted to mechanical equipment to observe it and help with predictive maintenance. Asset tracking and leak detection are also applications for flexible electronics in the industrial environment.</p><h1>Conclusion</h1><p>Flexible and printed electronics have made products smaller, lighter, and more malleable. In addition, this technology has opened doors to new form factors and different applications, providing biodegradable and recyclable solutions and a solution to electronic waste. The technology is already achieving high quality on an industrial level, with applications in multiple areas.&nbsp;</p><p>Among the breakthroughs, more efficient printing processes and materials, such as non-contact and contact printing, have been developed. Regarding trends, the utilization of organic light-emitting diodes (OLEDs), organic photovoltaic power (OPV), and printed TFTs have been a trend. However, some challenges such as instabilities, low efficiencies and improved substrates need to be overcome to solidify these technologies. Despite the challenges, flexible and printed electronics have the potential to significantly contribute to digital health, modernize automotive products, Industry 4.0 and IoT.&nbsp;</p><h1>References</h1><ol start="1" type="1"><li><a href="https://link.springer.com/chapter/10.1007/978-3-031-21610-7_3" target="_blank">https://link.springer.com/chapter/10.1007/978-3-031-21610-7_3</a></li><li><a data-lf-fd-inspected-kn9eq4roawkarlvp="true" href="https://ati.ec.europa.eu/sites/default/files/2021-04/Flexible%20and%20printed%20electronics.pdf" target="_blank">https://ati.ec.europa.eu/sites/default/files/2021-04/Flexible%20and%20printed%20electronics.pdf</a></li><li><a href="https://escholarship.org/uc/item/4xz53786" target="_blank">https://escholarship.org/uc/item/4xz53786</a></li><li><a href="https://www.mdpi.com/2504-4494/5/3/89" target="_blank">https://www.mdpi.com/2504-4494/5/3/89</a>&nbsp;</li><li>G. Grau, V. Subramanian, Fully high-speed gravure printed, low-variability, high-performance organic polymer transistors with sub-5 V operation. Adv. Electron. Mater. 2(4), 1500328 (2016). <a href="https://doi.org/10.1002/aelm.201500328" target="_blank">https://doi.org/10.1002/aelm.201500328</a>&nbsp;</li><li><a href="https://onlinelibrary.wiley.com/doi/full/10.1002/advs.201801445" target="_blank">https://onlinelibrary.wiley.com/doi/full/10.1002/advs.201801445</a></li><li><a href="https://www.idtechex.com/en/research-article/what-does-2023-hold-for-printed-flexible-electronics/28172" target="_blank">https://www.idtechex.com/en/research-article/what-does-2023-hold-for-printed-flexible-electronics/28172</a>&nbsp;</li><li><a href="https://www.tapecon.com/blog/how-printed-flexible-electronics-are-shaping-the-future" target="_blank">https://www.tapecon.com/blog/how-printed-flexible-electronics-are-shaping-the-future</a>&nbsp;</li><li><a href="https://www.idtechex.com/en/research-article/3d-electronics-an-alternative-to-pcbs/21456" target="_blank">https://www.idtechex.com/en/research-article/3d-electronics-an-alternative-to-pcbs/21456</a>&nbsp;</li></ol><p>&nbsp;</p>

Step into the cutting-edge technologies and future trends of flexible and printed electronics.

Flexible and Printed Electronics: Breakthroughs, Applications, and Challenges

<div data-testid="richTextElement" id="isPasted"><h1>The Future of Electronics: RESHAPED</h1></div><div data-testid="richTextElement"><p dir="ltr" id="isPasted">TechBlick invites engineers, researchers, entrepreneurs, inventors, and end users from around the world to the Innovation Festival, covering printed, additive, flexible, hybrid, 3D, and wearable electronics.&nbsp;</p><p dir="ltr"><strong>Thursday, 22 Jun, 10:30 &ndash; 21:20 CEST.&nbsp;</strong></p><p dir="ltr">The event takes place in TechBlick&rsquo;s unique virtual interactive platform.&nbsp;</p><p dir="ltr"><a class="button-main-action" href="https://wevlv.co/techblick-2023" rel="noopener noreferrer" target="_blank"><strong>Register for free here.</strong></a></p><p dir="ltr" id="isPasted">Printed and additive electronics is a diverse technology frontier already reshaping the future in human-machine interfaces &amp; smart surfaces, wearables and healthcare, electronics &amp; PCB manufacturing, advanced microelectronic packaging, automotive, photovoltaics, displays &amp; lighting, and much more.</p><div id="isPasted"><ul><li>65+ live online invited talks showcasing the state-of-the-art from around the world</li><li>75+ live online exhibitors</li><li>500+ participants</li><li>One-on-one speed networking (round-robin speed networking)</li></ul></div><div data-testid="richTextElement" id="isPasted"><h3>Speakers and events</h3></div><div data-testid="richTextElement"><p>Speakers from some of the world&#39;s leading companies will present their technology and research. Attendees will learn about the needs and case studies of key end-user companies.</p><p>Highlights include sessions on:&nbsp;</p><ul><li>Inkjet printable stretchable electrodes for organic electronic applications</li><li><p><span style="background-color: transparent;">3D Additive Lithography for Electronics</span></p></li><li><p><span style="background-color: transparent;">The potential of femtoliter-level droplet with super inkjet systems</span></p></li></ul><p><a href="https://www.techblick.com/innovation-festival-june-2023" rel="noopener noreferrer" target="_blank">Explore the festival agenda and networking events here.</a></p><h3>Who should attend?</h3><p>The event is a relevant opportunity for all engineers and designers curious about the future of flexible electronics as well as those experienced in the field.&nbsp;</p><div id="isPasted"><div><p>The event will attract a global community, from innovators and material suppliers to equipment makers, manufacturers, and end users.&nbsp;</p></div></div><h3>Register for the event</h3><p><a class="button-main-action" href="https://wevlv.co/techblick-2023" rel="noopener noreferrer" target="_blank">Register to attend this FREE event on 22 June 2023.</a></p><h3>Event sponsors:</h3></div><p><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjg0MTY4ODY1NzA5LVNwZWFrZXJzICMxIChGZXN0aXZhbC1KdW5lLTIwMjMpLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 300px;" class="fr-fic fr-dib"></p><p><br></p></div>

This free-to-attend, immersive virtual event, on 22 June 2023 will cover all aspects of flexible and printed electronics, from material advancements to the development of novel deposition and manufacturing technologies. 

Innovations Festival: Printed, Flexible, Hybrid, 3D, Wearable, & Textile Electronics

<p id="isPasted">Printed electronics is a promising additive technique to produce all manners of devices. It is already a very successful industry. However, &nbsp;some continue to consider only a technology of the future. This is partly because when printed electronics succeeeds, it is often no longer called printed electronics, leading some to overlook its current successes.</p><p><a href="https://www.techblick.com/" rel="noopener noreferrer" target="_blank">TechBlick</a> is the home of additive and printed electronics. In this TechBlick presentation - which was originally posted<a href="https://www.techblick.com/post/full-presentation-review-of-industrial-applications-of-printed-electronics-1" rel="noopener noreferrer" target="_blank">&nbsp;here</a>- &nbsp;aims to highlight a diverse range of printed electronics applications which are already industrialized today. This offers a good view of the depth and breadth of the industry, demonstrating how this technology is literally everywhere!</p><p><strong>You can download the slides accompaying this presentation<a href="https://www.techblick.com/post/full-presentation-review-of-industrial-applications-of-printed-electronics-1" rel="noopener noreferrer" target="_blank">&nbsp;here</a><br></strong></p><p>Here we will cover the following</p><ul><li>Printed metalization of Si PVs (PERC, Topcon, and HJT PVs)</li><li>Organic and Perovskite Photovoltaics</li><li>QD-OLED Displays</li><li>MicroLED Color Conversion</li><li>MLCCs</li><li>PCB Industry (solder printing, solder &amp; legend printing)</li><li>Automotive industry (from occupancy sensors to seat heaters to 3D touch surfaces)</li><li>Medical and Biosensors (from glucose test strips to multilayer precision biosensors)</li><li>HMIs</li><li>2.5D and 3D Electronics</li><li>Intelligent packaging</li><li>Semiconductor packaging</li><li>and many more</li></ul><p>To learn more about the world of printed and additive electronics, and to network with all the key players from around the world, please join us in <strong>Berlin on 17-19 OCT 2023</strong> where you can hear more than 50 onsite talks, visit more than 74 booths, and network with 600+ peers and partners. <a href="https://www.techblick.com/electronicsreshaped" rel="noopener noreferrer" target="_blank">Here</a> you can find mroe info</p><p><span class="fr-img-caption fr-fic fr-dib" style="width: 715px;"><span class="fr-img-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681376756569-email+%28Berlin-2023%29+%282%29.jpg" style="width: 713px;" class="fr-fic fr-dib"><span class="fr-inner" data-dl-input-translation="true"><a href="https://www.techblick.com/electronicsreshaped" id="isPasted" rel="noopener noreferrer" target="_blank">https://www.techblick.com/electronicsreshaped</a></span></span></span></p><p><br></p><p><br></p>

TechBlick's presentation reviews printed electronics' industrial applications, dispelling the notion that it's solely a technology of the future. The talk showcases various commercial success stories incl.  photovoltaics, displays, sensors, HMIs, 3D electronics,  MLCCs, PCBs, semicon packaging, etc

Review of industrial applications of printed electronics - what are current successful applications?

<p id="isPasted">Engineers at Duke University have produced the world&rsquo;s first fully recyclable printed electronics that replace the use of chemicals with water in the fabrication process. By bypassing the need for hazardous chemicals, the demonstration points down a path industry could follow to reduce its environmental footprint and human health risks.</p><p>The research appeared online Feb. 28 in the journal Nano Letters.</p><p><span class="fr-img-caption fr-fic fr-dib" style="width: 768px;"><span class="fr-img-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681253766429-ezgif-2-aeab43ebbb.gif" style="width: 766px;" class="fr-fic fr-dib"><span class="fr-inner">An aerosol jet printer puts down layers of carbon-based electronic inks to create transistors that can be fully recycled using only water, rather than requiring harsh, toxic chemicals. Credit - Jason Arthurs Photography&nbsp;</span></span></span></p><p>One of the dominant challenges facing any electronics manufacturer is successfully securing several layers of components on top of each other, which is crucial to making complex devices. Getting these layers to stick together can be a frustrating process, particularly for printed electronics.</p><blockquote><p>&quot;Putting layers on top of each other is not as easy as putting them down on their own &mdash; but that&rsquo;s what you have to do if you want to build electronic devices with printing.&rdquo;</p><p>AARON FRANKLIN</p></blockquote><p>&ldquo;If you&rsquo;re making a peanut butter and jelly sandwich, one layer on either slice of bread is easy,&rdquo; explained <a href="https://ece.duke.edu/faculty/aaron-franklin" target="_blank">Aaron Franklin</a>, the Addy Professor of Electrical and Computer Engineering at Duke, who led the study. &ldquo;But if you put the jelly down first and then try to spread peanut butter on top of it, forget it, the jelly won&rsquo;t stay put and will intermix with the peanut butter. Putting layers on top of each other is not as easy as putting them down on their own &mdash; but that&rsquo;s what you have to do if you want to build electronic devices with printing.&rdquo;</p><p>In previous work, Franklin and his group demonstrated the <a href="https://pratt.duke.edu/about/news/recyclable-printed-electronics" target="_blank">first fully recyclable printed electronics</a>. The devices used three carbon-based inks: semiconducting carbon nanotubes, conductive graphene and insulating nanocellulose. In trying to adapt the original process to only use water, the carbon nanotubes presented the largest challenge.</p><p>To make a water-based ink in which the carbon nanotubes don&rsquo;t clump together and spread evenly on a surface, a surfactant similar to detergent is added. The resulting ink, however, does not create a layer of carbon nanotubes dense enough for a high current of electrons to travel across.</p><p><span class="fr-video fr-deletable fr-fvc fr-dvb fr-draggable" contenteditable="false" draggable="true"><iframe width="640" height="360" src="https://www.youtube.com/embed/CCwVaUYbarc?&wmode=opaque&rel=0&enablejsapi=1&origin=https://www.wevolver.com" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe></span></p><p id="isPasted">&ldquo;You want the carbon nanotubes to look like al dente spaghetti strewn down on a flat surface,&rdquo; said Franklin. &ldquo;But with a water-based ink, they look more like they&rsquo;ve been taken one-by-one and tossed on a wall to check for doneness. If we were using chemicals, we could just print multiple passes again and again until there were enough nanotubes. But water doesn&rsquo;t work that way. We could do it 100 times and there&rsquo;d still be the same density as the first time.&rdquo;</p><p>This is because the surfactant used to keep the carbon nanotubes from clumping also prevents additional layers from adhering to the first. In a traditional manufacturing process, these surfactants would be removed using either very high temperatures, which takes a lot of energy, or harsh chemicals, which can pose human and environmental health risks. Franklin and his group wanted to avoid both.</p><p>In the paper, Franklin and his group develop a cyclical process in which the device is rinsed with water, dried in relatively low heat and printed on again. When the amount of surfactant used in the ink is also tuned down, the researchers show that their inks and processes can create fully functional, fully recyclable, fully water-based transistors.</p><blockquote><p>&quot;If we were using chemicals, we could just print multiple passes again and again until there were enough nanotubes. But water doesn&rsquo;t work that way. We could do it 100 times and there&rsquo;d still be the same density as the first time.&rdquo;</p><p>AARON FRANKLIN</p></blockquote><p>Compared to a resistor or capacitor, a transistor is a relatively complex computer component used in devices such as power control or logic circuits and sensors. Franklin explains that, by demonstrating a transistor first, he hopes to signal to the rest of the field that there is a viable path toward making some electronics manufacturing processes much more environmentally friendly.</p><p>Franklin has already proven that nearly 100% of the carbon nanotubes and graphene used in printing can be recovered and reused in the same process, losing very little of the substances or their performance viability. Because nanocellulose is made from wood, it can simply be recycled or biodegraded like paper. And while the process does use a lot of water, it&rsquo;s not nearly as much as what is required to deal with the toxic chemicals used in traditional fabrication methods.</p><p id="isPasted">According to a United Nations estimate, less than a quarter of the millions of pounds of electronics thrown away each year is recycled. And the problem is only going to get worse as the world eventually upgrades to 6G devices and the Internet of Things (IoT) continues to expand. So any dent that could be made in this growing mountain of electronic trash is important to pursue.</p><blockquote><p>&ldquo;The performance of our thin-film transistors doesn&rsquo;t match the best currently being manufactured, but they&rsquo;re competitive enough to show the research community that we should all be doing more work to make these processes more environmentally friendly.&quot;</p><p>AARON FRANKLIN</p></blockquote><p>While more work needs to be done, Franklin says the approach could be used in the manufacturing of other electronic components like the screens and displays that are now ubiquitous to society. Every electronic display has a backplane of thin-film transistors similar to what is demonstrated in the paper. The current fabrication technology is high-energy and relies on hazardous chemicals as well as toxic gasses. The entire industry has been&nbsp;<a href="https://www.epa.gov/climateleadership/sector-spotlight-electronics" target="_blank">flagged for immediate attention by the US Environmental Protection Agency</a>.</p><p>&ldquo;The performance of our thin-film transistors doesn&rsquo;t match the best currently being manufactured, but they&rsquo;re competitive enough to show the research community that we should all be doing more work to make these processes more environmentally friendly,&rdquo; Franklin said.</p><p>This work was supported by the National Institutes of Health (1R01HL146849), the Air Force Office of Scientific Research (FA9550-22-1-0466), and the National Science Foundation (ECCS-1542015, Graduate Research Fellowship 2139754).</p><p>CITATION: &ldquo;All-Carbon Thin-Film Transistors Using Water-Only Printing,&rdquo; Shiheng Lu, Brittany N. Smith, Hope Meikle, Michael J. Therien, and Aaron D. Franklin. Nano Letters, Feb. 28, 2023. DOI: 10.1021/acs.nanolett.2c04196</p>

First-of-its-kind demonstration suggests a more environmentally friendly future for the electronics industry is possible

Fully Recyclable Printed Electronics Ditch Toxic Chemicals for Water

<p id="isPasted">This article was written by Tsuyoshi Takeda from Panasonic for TechBlick and first appeared on <a href="https://www.techblick.com/post/beyolex-for-soft-circuit-solutions-panasonic" rel="noopener noreferrer" target="_blank">this link.</a> The Electronic Materials Business Division of Panasonic Industry Co.,Ltd. (Panasonic) is a premier supplier of electronic materials like printed circuit boards laminates, semiconductor packaging materials, display films and other leading-edge products.&nbsp;</p><p>Leveraging our core expertise in high-performance thermosetting polymer chemistry, we developed BEYOLEX&trade;, a fully cross-linked, non-silicone, thermosetting stretchable film. BEYOLEX&trade; is specifically designed as a soft, stretchable, and durable substrate for reliable printed electronics. BEYOLEX&trade; exhibits superior performance when compared to existing stretchable films like Thermoplastic Polyurethane (TPU) and Polydimethylsiloxane (PDMS) and is under evaluation and qualification for a wide variety of demanding applications. In collaboration with our innovative partners, Panasonic introduces our latest case studies on soft circuit development which is one of the promising applications of BEYOLEX&trade;.</p><hr><h3>Case Study 1: Pliable PCB made with copper sintering ink</h3><p>InnovationLab and Panasonic developed a pliable PCB demonstrator. This device was designed and manufactured by InnovationLab using BEYOLEX&trade; and sintered copper ink. Generally, the copper inks require a high sintering temperature (&gt;160 &deg;C), which is extremely challenging for TPU. As can be seen in Pic 1, the BEYOLEX&trade; substrate had no difficulty tolerating the sintering temperature and exhibited no damage from the process. Furthermore, the combination of the high temperature tolerance of BEYOLEX&trade; and the solderability of the sintered copper ink &nbsp;enabled component mounting with standard solders such as Sn-Bi or SAC305: resulting in reliable and high density assemblies and delivering a functional PCB with more pliability and softness than typical flexible printed circuits (FPCs.) 　</p><div data-hook="rcv-block12" type="paragraph"><br></div><div data-hook="imageViewer" tabindex="0"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjgxMjQzMzQ4MTIzLTE2ODEyNDMzNDgxMjMucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" alt="" data-pin-media="https://static.wixstatic.com/media/090711_4a367e5ea8b54dc3b278e4d91f691fab~mv2.jpg/v1/fill/w_900,h_742,al_c,q_85/090711_4a367e5ea8b54dc3b278e4d91f691fab~mv2.jpg" class="fr-fic fr-dii"></div><div data-hook="rcv-block14" type="image"><br></div><p>Pic 1: Pliable PCB made by InnovationLab</p><hr><p>Panasonic will be exhibiting at the TechBlick event on the Future of Electronics RESHAPED. Please join us in Berlin on 17-18 OCT 2023. More info <a href="https://www.techblick.com/electronicsreshaped" id="isPasted" target="_blank">here</a></p><p><span class="fr-img-caption fr-fic fr-dib" style="width: 766px;"><span class="fr-img-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681243834906-email+%28Berlin-2023%29.jpg" style="width: 766px;" class="fr-fic fr-dib"><span class="fr-inner" data-dl-input-translation="true"><a href="https://www.techblick.com/electronicsreshaped" id="isPasted" rel="noopener noreferrer" target="_blank">https://www.techblick.com/electronicsreshaped</a></span></span></span></p><hr><h3>Case Study 2: Stretchable hybrid PCB made using copper ink and stretchable silver paste&nbsp;</h3><div data-hook="rcv-block17" type="h3"><br></div><p>Kelenn Technology, a leading manufacturer of printing equipment, also makes functional inks that are customized for their printing systems. Using their proprietary Direct Material Deposition (DMD) technology, Kelenn Technology printed land pads with copper ink and circuit traces with stretchable silver-based paste onto BEYOLEX&trade; film (Pic 2). This hybrid circuit produced a solderable, stretchable PCB configuration that would be difficult to achieve with copper circuitry alone. Definitely, BEYOLEX&trade; is the only substrate solution for this design.&nbsp;</p><div data-hook="rcv-block19" type="paragraph"><br></div><div data-hook="rcv-block20" type="paragraph"><br></div><div data-hook="imageViewer" tabindex="0"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjgxMjQzMzQ4OTcxLTE2ODEyNDMzNDg5NzEucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" alt="" data-pin-media="https://static.wixstatic.com/media/090711_ec3b66bae7ef4a8bac4b59e8699970c5~mv2.jpg/v1/fill/w_900,h_717,al_c,q_85/090711_ec3b66bae7ef4a8bac4b59e8699970c5~mv2.jpg" class="fr-fic fr-dii"></div><div data-hook="rcv-block21" type="image"><br></div><p>Pic 2: Stretchable PCB made by Kelenn Technology &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;</p><p>Subsequently, Panasonic engineers reflowed solder paste onto test vehicles prepared by Kelenn Technology. We printed an industry standard SAC305 solder paste and reflowed the part in a Vapor Solder Oven with a temperature of 230&deg;C. We confirmed both the solderability of the copper ink pads provided by Kelenn Technology as well as the mechanical integrity of BEYOLEX&trade; after soldering (Pic 3). As a result of this test, we believe BEYOLEX&trade;, with sintered copper ink, is a promising solution for solderable, pliable or even stretchable PCB constructions.</p><div data-hook="rcv-block24" type="paragraph"><br></div><div data-hook="imageViewer" tabindex="0"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjgxMjQzMzQ1NzY4LTE2ODEyNDMzNDU3NjgucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" alt="" data-pin-media="https://static.wixstatic.com/media/090711_a29a1cd0f67343ecbbf3dea16b496471~mv2.jpg/v1/fill/w_900,h_556,al_c,q_85/090711_a29a1cd0f67343ecbbf3dea16b496471~mv2.jpg" class="fr-fic fr-dii"></div><div data-hook="rcv-block26" type="image"><br></div><p>Pic 3: Soldering on Cu</p><p>This technology will be presented at TechBlick&#39;s event in Berlin on 17-18 OCT 2023. You can learn more info<a href="https://www.techblick.com/electronicsreshaped" rel="noopener noreferrer" target="_blank"> here</a>. This is the most important global event on printed electronics, stretchable and soft electronics, and wearable electronics.&nbsp;</p><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1681243915891-email+%28Berlin-2023%29.jpg" style="width: 760px;" class="fr-fic fr-dib"><hr><h3>Case study 3: Tackling the challenges of truly stretchable electronics</h3><p>Stretchable silver pastes are an attractive conductor solution for new form factor devices. However, these polymer composite pastes have inherent limitations for forming truly stretchable electronics; typically, the resistance increases significantly with each elongation cycle and these increases are cumulative, climbing with each stretch cycle. A printable Liquid Metal Based Composite developed by University of Coimbra (UoC) is a promising solution to this issue. UoC&rsquo;s ink exhibits metallic conductivity and much lower resistance change during stretch cycles compared to silver-polymer pastes. Thanks to the lack of plastic deformation of BEYOLEX&trade;, UoC&rsquo;s ink printed on BEYOLEX&trade; looks to be a promising combination for truly stretchable electronics requiring repeated stretching (Pic 4).&nbsp;</p><div data-hook="rcv-block31" type="paragraph"><br></div><div data-hook="rcv-block33" type="empty-line"><br></div><div data-hook="imageViewer" tabindex="0"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjgxMjQzMzQ4NDAzLTE2ODEyNDMzNDg0MDMucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" alt="" data-pin-media="https://static.wixstatic.com/media/090711_7b7f233db9a746e6ad504d65e4c2c543~mv2.jpg/v1/fill/w_1200,h_787,al_c,q_85/090711_7b7f233db9a746e6ad504d65e4c2c543~mv2.jpg" class="fr-fic fr-dii"></div><div data-hook="rcv-block34" type="image"><br></div><p>Pic 4: Stretchable LED with capacitive touch by UoC</p><p>The soft-circuit solutions made with BEYOLEX&trade; introduced in this article are made by additive printing processes which are generally more environmentally friendly than the conventional subtractive PCB fabrication process. &nbsp;Panasonic&rsquo;s Electronic Materials Business Division keeps contributing to create value and to society through innovative materials.</p><p data-hook="rcv-block37" type="paragraph">Panasonic will be exhibiting at the TechBlick show on The Future of Electronics RESHAPED in Berlin on 17-19 OCT 2023. You can find more information <a href="https://www.techblick.com/electronicsreshaped" rel="noopener noreferrer" target="_blank">here</a></p><p><br></p>

A novel stretchable film has been developed for soft & stretchable circuit / electronic solutions, outperforming existing films like TPU.  Here you can learn about case studies showcasing its potential in pliable PCBs, stretchable hybrid PCBs, and truly stretchable electronics. 

A Novel Substrate for Soft Circuit Solutions: Case Studies and Results

<h2 dir="ltr" id="isPasted">Introduction</h2><p><span style="background-color: transparent;">Castellated holes enable reliable electric connection to another board through the edges. The half-plated semi-circular holes on the edge of a PCB are termed castellated holes. For a long time, castellated holes have been known to provide a stable electrical connection between two boards. Soon these half-plated holes simplified the process for small modules to fit on a large board. The unique manufacturing process of castellated holes has two stages where the holes are cut in half and plated with a conducting material. The top-notch features of using castellated holes in the PCB design process include robust connectivity, durability, and enhanced assembly process for complex components. The applications of castellated holes include IoT hardware, RF modules, and breakout boards.</span></p><h2 dir="ltr" id="isPasted">What are Castellated Holes?</h2><p dir="ltr">Castellated holes&nbsp;(plated half holes) are&nbsp;PCB&nbsp;holes cut through the&nbsp;edges of the board, forming a half-circular shape. These holes are then plated with a conductive material, such as gold or&nbsp;copper layers, to create an&nbsp;electrical connection&nbsp;between the two sides of the board.&nbsp;Castellated holes&nbsp;differ from regular vias and&nbsp;plated-through holes&nbsp;(PTH) because they are engineered to facilitate easy and reliable connections between two&nbsp;PCBs. Proper connection makes&nbsp;castellated holes&nbsp;suitable for modular designs and&nbsp;surface-mount&nbsp;technology (SMT) components.</p><h2 dir="ltr">History of Castellated Holes</h2><p dir="ltr">Castellated holes&nbsp;date back to the early days of&nbsp;PCB design&nbsp;when engineers were experimenting with different methods of connecting circuit boards. The term &quot;castellated&quot; is adapted because these holes had a similar appearance to the crenellated pattern found on the top of mediaeval castle walls. Over the years,&nbsp;castellated holes&nbsp;have become more precise, reliable, and easier to work with. The process has drastically evolved with the advancements in&nbsp;PCB manufacturing&nbsp;technology. They are now a reliable alternative to a wide range of applications ranging from IoT devices to radio frequency&nbsp;modules&nbsp;and&nbsp;breakout boards.</p><h2 dir="ltr">Applications of Castellated holes</h2><p dir="ltr">Castellated holes PCB&nbsp;are versatile enough to serve a variety of applications in telecommunications,&nbsp;consumer electronics, automobiles and industrial systems. Some of the most common uses for&nbsp;castellated holes&nbsp;include:</p><h3 dir="ltr">IoT Devices</h3><p dir="ltr">The Internet of Things (IoT) is a rapidly growing industry that deploys efficient hardware to connect and communicate with each other. One of the challenges in designing IoT devices is the reliable connection of hardware to other components and systems.&nbsp;Castellated holes&nbsp;provide a stable and secure connection between&nbsp;PCB boards&nbsp;in IoT systems. IoT devices that utilize&nbsp;castellated PCBs&nbsp;include smart home systems, wearables, and sensor networks.</p><h3 dir="ltr">RF Modules</h3><p dir="ltr">Radiofrequency (RF)&nbsp;PCB modules&nbsp;are essential components in wireless communication devices including smartphones, tablets, and laptops.&nbsp;Castellated holes&nbsp;are used in the&nbsp;Bluetooth&nbsp;and&nbsp;Wi-Fi modules&nbsp;to provide a reliable connection between the&nbsp;module&nbsp;and the main board. The unique shape and design of&nbsp;castellated holes&nbsp;ensure optimal performance for wireless communication devices. The stable connection helps to minimize signal loss and interference.</p><h3 dir="ltr">Breakout Boards</h3><p dir="ltr">Breakout boards&nbsp;are&nbsp;small modules&nbsp;or&nbsp;PCBs&nbsp;designed to simplify the use of larger circuits and complex components, such as microcontrollers and sensors. These boards provide an accessible interface for connecting components to a larger system.&nbsp;Castellated holes&nbsp;are commonly used in&nbsp;breakout boards&nbsp;to provide a robust and reliable connection between the&nbsp;breakout board&nbsp;and the main&nbsp;PCB. The stable connection through&nbsp;castellated holes PCB&nbsp;simplifies the&nbsp;assembly process&nbsp;of complex components that may have high pin density. It is because castellated holes offer the feature of reorganisation of component pin layout to reduce the risk of damage during installation.</p><h2 dir="ltr">Benefits of Using Castellated Holes</h2><p dir="ltr">The use of castellated holes in PCB design offers several advantages, contributing to their growing popularity among engineers and designers. These benefits include improved connectivity, enhanced durability, simplified assembly processes, and board-to-board soldering capabilities.<br id="isPasted"><br>Castellated holes provide an excellent connection between two PCBs, ensuring minimal signal loss and optimal electrical performance. This robust connection significantly improves the overall performance and reliability of electronic devices, making them an efficient option for designers looking to maximize the efficiency and functionality of their products.<br><br>In addition to improved connectivity, castellated holes are designed to withstand the stresses of repeated connection and disconnection, making them more durable than traditional vias or plated through holes. This increased durability is particularly important in applications that require repeated hardware replacement and updating, such as IoT devices or modular electronics systems.</p><p dir="ltr"><span class="fr-img-caption fr-fic fr-dib" style="width: 302px;"><span class="fr-img-wrap"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjgwNzc1MDUxODY4LXNodXR0ZXJzdG9ja18xOTM1MTE1Mzk3ICgxKS5qcGciLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjk1MCwiZml0IjoiY292ZXIifX19" style="width: 300px;" class="fr-fic fr-dib"><span class="fr-inner">The thickness of the plating material used in castellated holes can significantly impact their electrical performance and durability.</span></span></span>One of the most significant advantages of using castellated holes is the simplification of the assembly process for PCBs. By reducing manufacturing complexity and improving product reliability, castellated holes allow for easy alignment and connection between two PCBs. The half-circular shape of the holes eliminates the risk of misalignment or damage during PCB assembly, and it also enables alterations to the pin layout.<br><br>Lastly, castellated holes facilitate board-to-board soldering, allowing small PCB modules to act as subcircuits for larger PCBs with inverters or filters. The tight connection between the two boards ensures the quality of the solder joint and reduces the chances of dirt accumulation, making castellated holes an advantageous choice for various applications.</p><h2 dir="ltr">Design Considerations for Castellated Holes</h2><p dir="ltr">There are several&nbsp;design attributes&nbsp;to consider during the design process for enhancing performance capabilities. Some of these factors include:</p><h3 dir="ltr">Hole Size and Spacing</h3><p dir="ltr">Choosing the appropriate hole size and spacing is crucial for castellated hole design. The hole diameter and size should be large enough to accommodate the insertion of the component leads or pins and provide adequate clearance for soldering. If you need to reduce the required diameter on the castellated vias, ENIG surface finish is the best option. However, the surface finish largely depends upon the castellated hole application. Spacing between the number of holes should be sufficient to prevent solder bridging and ensure proper electrical isolation between connections. Designers should adhere to manufacturer guidelines and industry standards to design castellated modules. Guidelines suggest that the minimal diameter of the hole should be 0.6 mm and spacing between two castellated holes should be 0.55 mm.&nbsp;</p><p dir="ltr"><span class="fr-img-caption fr-fic fr-dib" style="width: 302px;"><span class="fr-img-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1680775336673-shutterstock_1111624328+%281%29.jpg" style="width: 300px;" class="fr-fic fr-dib"><span class="fr-inner">Adequate edge clearance is essential to prevent mechanical stress and potential damage to the PCB during assembly or operation.</span></span></span></p><h3 dir="ltr">Plating Thickness of plated half holes</h3><p dir="ltr">The thickness of the plating material used in castellated holes can significantly impact their electrical performance and durability. Thicker plating materials provide a better connection but may also increase manufacturing costs and complexity. Designers should carefully consider the plating thickness requirements for their specific application. Usually, the plating thickness for holes is in the order of 20-25 microns.&nbsp;</p><h3 dir="ltr">Edge Clearance</h3><p dir="ltr">Edge clearance refers to the distance between the edge of the&nbsp;castellated hole&nbsp;and the&nbsp;board outline. Adequate edge clearance is essential to prevent mechanical stress and potential damage to the&nbsp;PCB&nbsp;during assembly or operation. Designers should follow industry standards and adhere to manufacturer guidelines for determining the appropriate edge clearance for their specific application.</p><h2 dir="ltr">Manufacturing Challenges and Solutions</h2><p dir="ltr">Castellated holes&nbsp;may have several manufacturing issues that may impact the overall quality and reliability of the final product. Some of these challenges are listed below with their possible solutions:</p><h3 dir="ltr">Alignment and Positioning</h3><p dir="ltr">Accurate alignment and positioning of&nbsp;castellated holes&nbsp;are crucial for proper&nbsp;electrical connections&nbsp;and limiting the risk of damage during the&nbsp;assembly process. Design software can improve the alignment and positioning of&nbsp;castellated holes&nbsp;and check whether the tolerance levels are met.</p><h3 dir="ltr">Solder Bridging</h3><p dir="ltr">Solder&nbsp;bridging is a common issue occurring in&nbsp;castellated hole&nbsp;assembly when excess&nbsp;solder&nbsp;creates unintended&nbsp;electrical connections&nbsp;between adjacent holes. To prevent&nbsp;solder&nbsp;bridging, designers should check proper hole spacing and employ&nbsp;solder mask&nbsp;designs. Furthermore, the designers must ensure that the&nbsp;assembly process&nbsp;includes appropriate&nbsp;soldering&nbsp;techniques and quality control measures.</p><h3 dir="ltr">Board Warping</h3><p dir="ltr">When&nbsp;PCB&nbsp;is subjected to high temperatures in the&nbsp;manufacturing process&nbsp;or operation, board warping (change in&nbsp;PCB&nbsp;geometry) may occur due to the usage of&nbsp;castellated holes. To minimize board warping, designers should consider using materials with low coefficients of thermal expansion and implementing appropriate thermal management strategies in their designs.</p><h2 dir="ltr">Conclusion</h2><p dir="ltr">Castellated holes&nbsp;are&nbsp;indentations&nbsp;in the form of semi-plated holes over the&nbsp;edge of a PCB board. The advantages and applications make these holes an essential tool in&nbsp;PCB&nbsp;and&nbsp;pad design&nbsp;for professionals. Besides the benefits,&nbsp;castellated holes&nbsp;require careful attention to the design considerations and have associated manufacturing challenges. Engineers and designers can incorporate&nbsp;castellated holes&nbsp;into their next electronic design project to maximize the quality of results.&nbsp;Castellated holes&nbsp;create innovative, efficient, and reliable electronic devices!</p><h2 dir="ltr">Frequently Asked Questions</h2><p dir="ltr">To further deepen your understanding of&nbsp;castellated holes, here are some frequently asked questions and their answers:</p><ol id="isPasted"><li dir="ltr"><p dir="ltr"><strong>What materials are used for castellated hole plating?</strong><br>Castellated hole&nbsp;plating typically consists of copper, followed by a thin layer of nickel. The final layer may contain gold or another corrosion-resistant material. This combination provides excellent electrical conductivity, durability, and resistance to oxidation.</p></li><li dir="ltr"><p dir="ltr"><strong>Can castellated holes be used with flexible PCBs?</strong><br>Yes,&nbsp;castellated holes&nbsp;can be used with flexible&nbsp;PCBs. However, special considerations should be taken into account during the design and&nbsp;manufacturing process&nbsp;to ensure proper alignment and connection between the flexible&nbsp;PCB&nbsp;and the mating board.</p></li><li dir="ltr"><p dir="ltr"><strong>Are there any specific design software recommendations for working with castellated holes?</strong><br>Most modern&nbsp;PCB fabrication&nbsp;and design software packages like Altium Designer, OrCAD, and KiCad support&nbsp;castellated hole&nbsp;design. These software packages typically include features,&nbsp;tutorials, and tools specifically designed to streamline the procedures involving&nbsp;castellated holes.</p></li><li dir="ltr"><p dir="ltr"><strong>What are the cost implications of using castellated holes in PCB design?</strong><br>Incorporating&nbsp;castellated holes&nbsp;into your&nbsp;PCB design&nbsp;can increase manufacturing costs due to the additional processing steps required for cutting and plating the holes. However, the benefits of improved connectivity, durability, and a simplified&nbsp;assembly process&nbsp;can often offset these additional costs, making&nbsp;castellated holes&nbsp;a cost-effective solution for many applications.</p></li><li dir="ltr"><p dir="ltr"><strong>How do castellated holes impact the overall size and weight of a PCB?</strong><br>Castellated holes&nbsp;can reduce the overall size and weight of a&nbsp;PCB&nbsp;by eliminating the need for additional&nbsp;connectors&nbsp;or components to facilitate connections between boards. The&nbsp;assembly process&nbsp;simplifies to a more compact design as&nbsp;castellated holes&nbsp;contribute to smaller, lighter, and more efficient electronic devices.</p></li></ol><h2>References</h2><ol id="isPasted"><li dir="ltr"><p dir="ltr">IPC, IPC-2221B, Generic Standard on Printed Board Design,<a href="https://www.ipc.org/" target="_blank">&nbsp;https://www.ipc.org</a></p></li><li dir="ltr"><p dir="ltr"><span style="background-color: transparent;">IPC, IPC-6012D, Qualification and Performance Specification for Rigid Printed Boards,</span><a href="https://www.ipc.org/" style="background-color: transparent;" target="_blank">&nbsp;https://www.ipc.org</a></p></li></ol><p><br></p>

Castellated holes are extensively used in the printed circuit board (PCB) design process. This article is a detailed overview of castellated holes, covering their history, application, benefits, design attributes, challenges, and significance in modern electronic design.

Castellated Holes: The Ultimate Guide to Their Advantages and Applications

<p id="isPasted"><span style="background-color: transparent;">Introduction: Electrical 3D printing has been revolutionizing the printed electronics industry, offering rapid prototyping and the ability to manufacture unique, complex devices. In this blog post, we dive into the exciting world of electrical 3D printers, exploring their capabilities, applications, and the innovative processes that make them stand out from the crowd.&nbsp;</span></p><p>The video above is the talk given by &nbsp;<strong>Fuji Corporation&nbsp;</strong>at the <a href="https://www.techblick.com/" rel="noopener noreferrer" target="_blank">TechBlick</a> event in 2022. The points below are summaries based on this talk <strong>and the entire talk can be viewed above. </strong></p><p>&nbsp;TechBlick&#39;s next conference will take place on 17-18 OCT 2023 in Berlin. Join us to learn about all aspects of additive electronics. The latest advances of this technology will be showcased. Learn more <a href="https://www.techblick.com/electronicsreshaped" rel="noopener noreferrer" target="_blank">here<strong>&nbsp;</strong></a></p><hr><h2><strong>All-in-One Machine for Printed Electronics:</strong></h2><p>One of the most intriguing advancements in the field is the development of an all-in-one machine that can perform multiple functions, such as resin printing, circuit formation, and part mounting. This integration enables the creation of printed circuit boards (PCBs) within a single day using a full additive process. Furthermore, the machine can import design data directly and provide optimized process conditions for customers.</p><p><strong><span class="fr-img-caption fr-fic fr-dib" style="width: 701px;"><span class="fr-img-wrap"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjgwNzk2Nzg2NzEyLWVtYWlsIChCZXJsaW4tMjAyMyktV2hpdGUuanBnIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 701px;" class="fr-fic fr-dib"><span class="fr-inner" data-dl-input-translation="true"><a href="https://www.techblick.com/electronicsreshaped" id="isPasted" rel="noopener noreferrer" target="_blank">https://www.techblick.com/electronicsreshaped</a></span></span></span></strong></p><h3><span style="background-color: transparent;">Rapid Prototyping and Unique Device Manufacturing:</span></h3><p>Electrical 3D printers have two main applications: rapid prototyping and manufacturing unique, complex devices. With rapid prototyping, engineers can design and produce IoT devices, microcomputers, Bluetooth modules, battery regulators, and sensors in a fraction of the time it would take using traditional methods. For unique device manufacturing, the printers can create intricate, multidimensional structures for innovative products, such as heartbeat sensors or other wearable technologies.</p><h3>Innovative Materials and Processes:</h3><p>Collaboration with chemical suppliers has led to the development of unique materials, such as UV resins with high durability under high-temperature conditions, and low-temperature sintering silver nanoparticle inks. These materials enable 3D printers to create circuits with fine tolerances, smooth surfaces, and optimal electrical properties.</p><h3>Low-Temperature Soldering Process:</h3><p>One challenge faced by printed electronics is the high-temperature soldering process traditionally used in PCB assembly. However, new developments in conductive paste and low-modulus materials have enabled a unique, low-temperature soldering process at around 80 degrees Celsius. This approach minimizes thermal stress on components and creates stable electrical connections.</p><h3>Embedded Components and Parts Encapsulation:</h3><p>The integration of multiple processes within a single machine opens up possibilities for embedded components and parts encapsulation. By creating additional layers of resin and circuits over mounted components, electrical 3D printers can achieve a uniform surface suitable for further part mounting or advanced device structures.</p><h3><strong>Conclusion:</strong></h3><p>The advancements in electrical 3D printing technology are poised to transform the electronics industry, providing rapid prototyping and manufacturing capabilities for complex devices. These innovations have the potential to minimize waste, reduce transportation energy, accelerate innovation, and contribute to greater engineering equality worldwide. As more companies invest in this technology, we can expect to see continued growth and innovation in the field of printed electronics.</p><p><span class="fr-video fr-deletable fr-fvc fr-dvb fr-draggable fr-active" contenteditable="false" draggable="true"><iframe width="640" height="360" src="https://player.vimeo.com/video/815379464" frameborder="0" allowfullscreen="" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe></span><br></p>

In this article+talk, electrical 3D printing's technical aspects are covered, covering resin printing, circuit formation, part mounting, materials, and methods. Learn about low-temperature soldering, embedded components, and the impact on rapid prototyping and unique device manufacturing. 

Revolutionizing Printed Electronics with Cutting-Edge 3D Printers

<h2 dir="ltr" id="isPasted">Introduction</h2><p dir="ltr">A via is a metallic drilled hole that interconnects the circuitry of a circuit board. This hole transmits electrical signals between the various layers of a PCB. Therefore, it is especially useful for multilayer boards. Vias essentially serve as conductive pathways through which electrical signals travel between circuit layers. The advent of vias facilitated the production of smaller PCB sizes and more portable electronic devices, by implication.</p><p dir="ltr"><strong>Recommended Reading:</strong> <a href="https://www.wevolver.com/article/what-is-a-via-a-comprehensive-guide" rel="noopener noreferrer" target="_blank"><em>What is a Via: A Comprehensive Guide</em></a></p><p dir="ltr">PCB manufacturers make the via hole conductive by placing copper cylinders in the drilled holes. Then they fill the inner layer of the via with a non-conductive material. There are different versions of via covering and filling, all specified in international standard IPC 4761. The Filled Via is one of these specifications. Via hole filling is a process where the via hole of a PCB is filled with a solder mask or resin.</p><h2 dir="ltr">Definition of Filled Via</h2><p dir="ltr">A filled via is a via hole that is completely closed using a conductive or non-conductive epoxy material or copper plating. The practice of filling vias is a PCB manufacturing technique that serves to enhance the reliability of the circuit board by reducing the probable occurrence of trapped air or liquid in the via, which can lead to failures during the assembly process.</p><h2 dir="ltr">Benefits of using Filled Vias&nbsp;</h2><p dir="ltr">Microvias, buried vias, and plated through-holes are filled with conductive or non-conductive materials for the following benefits:</p><ul><li dir="ltr"><p dir="ltr">Tighter BGA pitches&nbsp;</p></li><li dir="ltr"><p dir="ltr">EMI reduction</p></li><li dir="ltr"><p dir="ltr">Increased heat dissipation and electrical conductivity</p></li><li dir="ltr"><p dir="ltr">Reduced layer count or board size, which translates to overall cost reduction</p></li><li dir="ltr"><p dir="ltr">Boosts routing density&nbsp;</p></li><li dir="ltr"><p dir="ltr">More secure Pad attachment</p></li><li dir="ltr"><p dir="ltr">Gives high-frequency designs the shortest possible route to bypass capacitors</p></li><li dir="ltr"><p dir="ltr">Negates problems in high-speed design and constraints such as low inductance[1]</p></li></ul><h2 dir="ltr">Types of Filled Vias</h2><p dir="ltr">There are options in the practice of filled vias, typed into the following:</p><h3 dir="ltr">Copper Filled Vias</h3><p dir="ltr">To manufacture copper-filled vias, the PCB through holes are filled with epoxy resin and copper. This requires extra materials that hike the cost of board production, but copper-filled vias make a PCB more suitable for certain applications. They also possess capabilities that other conductive fillings do not offer.&nbsp;</p><p dir="ltr" id="isPasted">PCBs with copper-filled vias are more beneficial than boards with copper-plated vias in the following aspects:</p><ul><li dir="ltr"><p dir="ltr">Thermal conductivity: When a via is filled with copper, its thermal conductivity increases. Keeping the heat away from the board will lengthen its lifespan and prevent defects in applications where high heat is required. Due to copper&#39;s strong thermal conductivity, this heat is drawn to it and kept off of the PCB&#39;s crucial sections. The heat flows through the copper from one side of the board to the other instead of moving to different parts of it.</p></li><li dir="ltr"><p dir="ltr">Electrical conductivity: Copper-filled vias are also suitable for applications that involve the movement of strong currents from one side of the board to the other. Large currents can flow through to inner layers without overloading the PCB, due to the copper&#39;s conductivity. Due to this capability, designers frequently request copper-filled vias for PCBs that will be exposed to high voltage levels. Therefore, copper-filled vias are often preferred for PCBs that are made for high voltage levels.</p></li></ul><h3 dir="ltr">Conductive Polymer Filled Vias</h3><p dir="ltr">Conductive via filling improves the thermal transfer capabilities of the via while enabling efficient electrical signal transmission from one side of the circuit board to the other. The most common materials used in conductive filled vias are copper or silver epoxy. They do very well in conducting a large amount of heat away from components as the metallic nature of the fill transfers heat away from the IC to the other side of the board where it is further dissipated by a heat sink.</p><p dir="ltr">Although copper conductive epoxy has significantly superior heat conductivity, silver epoxy is more affordable and more often utilized. However, A conductive polymer layer deposition method on the via-hole of a printed circuit board can reduce manufacturing costs by directly metalizing the inner wall of the via hole without creating a void. All these will enhance the current flow between the vias and internal layers of the PCB.</p><p dir="ltr">It is noteworthy that there can be a significant difference in the coefficient of thermal expansion or CTE between the metallic fill and the surrounding laminate. Metal heats up and expands a lot faster than laminate. As a result of this uneven expansion, a fracture may develop between the pad and the hole wall.</p><h3 dir="ltr">Non-Conductive Filled Vias</h3><p dir="ltr">Non-conductive filled vias are processed the same as conductive filled vias, however, instead of transferring heat and a signal, it is often done to stop solder or other impurities from entering the via. Moreover, it offers structural support for a copper pad that, in the case of a via-in-pad, covers the hole.</p><p dir="ltr">PCB manufacturers usually use the non-conductive epoxy paste to fill a regular via. The solder mask on these filled vias stops a few mils short of the pad. This is acceptable for medium-density boards because the presence of the solder mask lessens the possibility of solder bridging between the via and the nearby pad. The vias are still plated with copper, allowing them to carry heat and electrical signals. So the sole difference between these and traditional vias is that the fill material fills the gap in which air had existed.</p><p dir="ltr">It is always advised to match the CTE values of the via filling to be applied with the surrounding laminate to avoid future stress fractures brought on by expansion or contraction from the same circumstances as previously described in conductive filled vias. [2]</p><h2 dir="ltr">Filled Vias Manufacturing Process</h2><p dir="ltr">The manufacturing process for filled vias, just as in general PCB fabrication, requires the board to be cleaned and prepped. After ensuring that it is devoid of contaminants, the via-filling process can begin.</p><h3 dir="ltr">Drilling of Vias</h3><p dir="ltr">Two common methods for creating vias are the use of mechanical drill bits, and the use of a laser beam (usually used for microvias). All these methods have their own advantages and drawbacks. The choice of the method is made considering various factors like cost, number of PCBs in production, the required precision, hole depth, diameter, etc.</p><p dir="ltr">To avoid breakout during drilling, the annular ring around the hole where the vias are installed must be sufficient. This risk is present because mechanical drills tend to stray a little bit during the fabrication process. Via drill sizes must also be calculated with the proper aspect ratio, for an effective drill to be achieved.</p><p dir="ltr"><span class="fr-img-caption fr-fic fr-dii" style="width: 758px;"><span class="fr-img-wrap"><img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1678349747926-Via_hole_.jpg" width="450" height="329" class="fr-fic fr-dii"><span class="fr-inner">Via hole after drilling</span></span></span></p><h3 dir="ltr">Cleaning of Vias</h3><p dir="ltr">The via holes are cleaned of debris from the drilling operation. This can range from burrs on the edge of the holes to resin residue inside the holes. Cleaning is done using a combination of abrasive mechanical and chemical processes.</p><p dir="ltr">Moreover, cleaning the PCB with a brush and solvent ensures a finer and smoother drilling process. The board goes through numerous baths for cleaning and plating, and the entire process is closely monitored to ensure that copper is evenly plated within the via holes.</p><h3 dir="ltr">Filling of Vias</h3><p dir="ltr">In this stage, the via is filled with non-conductive or conductive material. The process of filling the holes with resin is conducted in two phases. In the first, the holes are filled with pressure and vacuum to allow efficient filling of the holes without developing gaps in the resin. Then in the second phase, a surface cleaning of the panel is conducted to get rid of the excess resin. This serves as a prep for the following planarization.</p><h3 dir="ltr">Planarization of Filled Vias</h3><p dir="ltr">After polymerization is complete, the resin is removed by a mechanical brushing action, called planarization, which is typically performed with specialized machines that employ cup brushes or with horizontal brushing machines. <span style="background-color: transparent;">This process essentially involves flattening and smoothening the copper surface, aimed at removing the excess resin and creating a uniform surface. It prepares the filled vias for over-plating with copper to allow the ideal soldering of electronic components. [3]</span></p><h2 dir="ltr">Applications of Filled Vias</h2><p dir="ltr">Filled vias are instrumental in the implementation of Via-In-Pad. In this process, vias are filled, planarized, and plated over with copper. It is also known as active pad and is gaining popularity and increased preference to transmit signal from the BGA through the via and onto inner layers instead of the traditional <span style="background-color: transparent;">&ldquo;dog bone&rdquo; method. The Via-In-Pad process can have major advantages over through-hole technology, even though it is cost intensive.&nbsp;</span><span style="background-color: transparent;">Moreover, filled vias are highly applicable for PCBs of medium density as the solder mask minimizes the chances of solder bridging between the pad and the via.</span></p><h2 dir="ltr">Challenges in using Filled Vias&nbsp;</h2><p dir="ltr">Filled vias offer many benefits for PCB fabrication, however, manufacturers face some challenges in implementing them with different applications. As a prominent product of filled vias, Via-in-pads show some fabrication issues. For instance, the soldering process can cause the via hole to get filled up, making it useless. Therefore, a minimal number of via-in-pads is recommended.&nbsp;</p><p dir="ltr"><span style="background-color: transparent;">Also, the copious intermediate steps required make filled vias cost-intensive and there is the present risk of uneven copper erosion during resurfacing, as well as structuring-related issues. [4]</span></p><h2 dir="ltr">Key Takeaways&nbsp;</h2><p dir="ltr">The filled via is the result of a PCB manufacturing technique that involves filling a via hole with epoxy to completely close the hole. The epoxy filling can be done with a conductive or non-conductive material, thereby creating distinct types of filled vias. Filled vias facilitate more reliable surface mounts (SMD), better assembly yields, and improved PCB reliability.</p><h2 dir="ltr">References&nbsp;</h2><p dir="ltr">1. PCB Directory. What is Via Filling? 2021. [Cited 2023 Mar 6] Available from: <a href="https://www.pcbdirectory.com/community/what-is-via-filling" style="background-color: transparent;" target="_blank">https://www.pcbdirectory.com/community/what-is-via-filling</a></p><p dir="ltr">2. Moko Technology. What is PCB Via?. 2022. [Cited 2023 Mar 6] Available from: <a href="https://www.google.com/amp/s/www.mokotechnology.com/what-is-pcb-via/amp/" style="background-color: transparent;" target="_blank">https://www.google.com/amp/s/www.mokotechnology.com/what-is-pcb-via/amp/</a></p><p dir="ltr">3. PCB Universe. Via Tenting, Plugging, and Filling. 2022. [Cited 2023 Mar 6] Available from: <a href="https://www.pcbuniverse.com/pcbu-tech-tips.php?a=5" style="background-color: transparent;" target="_blank">https://www.pcbuniverse.com/pcbu-tech-tips.php?a=5</a></p><p dir="ltr">4. NCAB Group. Via Hole Plugging - What is it and When Can it be Used? 2021. [Cited 2023 Mar 6] Available from: <a href="https://www.ncabgroup.com/blog/via-hole-plugging-what-is-it-and-when-can-it-be-used/" style="background-color: transparent;" target="_blank">https://www.ncabgroup.com/blog/via-hole-plugging-what-is-it-and-when-can-it-be-used/</a></p>

Filled vias are via holes that are completely filled and closed with conductive or non-conductive material or copper plating. The filled via is one of the many realizations of PCB via covering, specified by industry standards. This article covers the definition, benefits, processes, applications, and challenges of filled vias.