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Electronics Prototyping


Printed Electronics

Way back in 2011 we looked at the state of Printed Electronics and concluded this was a rapidly emerging area of Technology and had been since the previous look at The Future of Low Cost Electronics Manufacture in 2009. It has been a while so what has happened since then?

Printed Electronics

Printed Electronics

This is another guest post by Andrew Walla.

Andrew Walla

Andrew Walla

Printed Electronics Overview

Rapid prototyping, also referred to as 3D printing or additive manufacturing is the process of building objects or devices by building up layer by layer [1]. It has been identified as a potentially disruptive technology in the manufacturing industry in the coming years and is particularly well suited to provide benefits to technologies that operate on smaller scales of production [2]. New manufacturing paradigms, such as direct manufacturing (directly printing the sold goods) and home manufacturing (providing the capability for consumers to produce parts themselves) are set to change the way that small manufacturing businesses operate and significantly increase the level of competition in the industry [3].

This post will discuss the manufacturing technique of printing – a technology whose origins date back more than five centuries [4] and in this time a number of different printing methods have been developed. Successive layers are generally printed onto a substrate either by direct contact; via an impression cylinder (such as in flexographic, graviture or offset printing), deposited via a stencil (screen printing); or directly deposited onto the substrate (for example, inkjet printing, aerosol-jet printing or organic vapor-jet printing). Of these technologies, inkjet printing is particularly well suited to rapid prototyping and low volume manufacturing due to its high customisability, relatively high resolution and relatively low set-up cost [1].

Inkjet printed electronics differs to conventional inkjet printing in that the deposited substances need to exhibit desired electronic behaviours. A common method to achieve this is to intersperse the ink (a solvent) with nano-particles (small particles with controlled sizes, typically in the order of nano-meters) with desired conductive, dielectric or semiconducting characteristics. The printed substance might be treated post printing in order to evaporate the solvent and/or facilitate a chemical change in the nano-particles. Examples of such treatment include thermal curing [5], curing by ultraviolet light [6], laser sintering [7], e-beam sintering [8], chemical sintering [9] or plasma sintering [10].

Current research efforts are focusing on improving the printing and post-processing technologies available [10-12], improved interconnects [13] and vias [14], improved semiconductors, and printing under less stringent conditions. Examples include printing conductors at room temperature [6] and printing elements such as transistors [15] and diodes [16] with ever increasing performance characteristics. It is forecast that these improvements will continue for some time, as the fastest known inkjet printed transistor has an operating speed of around 20MHz [17-18]. (This is several orders of magnitude behind the capability of existing silicon chip technology.) Researchers are also working on developing transistor characteristics other than maximum frequency. For example, inkjet printing technology has been used to produce flexible and transparent transistors [19].

For those looking to predict where printed electronics will have the greatest future impact, it may pay to think outside the box. In the authour’s opinion, inkjet printing technology is likely to play a larger role in enabling new applications than it is to replace existing electronic technology. It is unlikely that a device with the functionality of a smartphone will be printed anytime soon, but perhaps the capability of printing your own solar panels is closer than you think.

[1] N. Saengchairat, T. Tran and C.-K. Chua, “A review: additive manufacturing for active electronic components,” Virtual and Physical Prototyping, vol. 12, no. 1, pp. 31-46, 2017.
[2] A. O. Laplume, B. Petersen and J. M. Pearce, “Global value chains from a 3D printing perspective,” Journal of International Business Studies, vol. 47, pp. 595-609, 2016.
[3] T. Rayna and L. Striukova, “From rapid prototyping to home fabrication: How 3D printing is changing business model innovation,” Technological Forecasting & Social Change, vol. 102, pp. 214-224, 2016.
[4] S. H. Steinberg, Five hundred years of printing, Maryland: Courier Dover Publications, 2017.
[5] N. Graddage, T.-Y. Chu, H. Ding, C. Py, A. Dadvand and Y. Tao, “Inkjet printed thin and uniform dielectrics for capacitors and organic thin film transistors enabled by the coffee ring effect,” Organic Electronics, vol. 29, pp. 114-119, 2016.
[6] G. McKerricher, M. Vaseem and A. Shamim, “Fully inkjet-printed microwave passive electronics,” Microsystems & Nanoengineering, vol. 3, p. 16075, 2017.
[7] S. H. Ko, H. Pan, C. P. Grigoropoulos, C. K. Luscombe, J. M. J. Fréchet and D. Poulikakos, “All-inkjet-printed flexible electronics fabrication on a polymer substrate by low-temperature high-resolution selective laser sintering of metal nanoparticles,” Nanotechnology, vol. 18, pp. 1-8, 2007.
[8] Y. Farraj, M. Bielmann and S. Magdassi, “Inkjet printing and rapid ebeam sintering enable formation of highly conductive patterns in roll to roll process,” The Royal Society of Chemistry, vol. 7, pp. 15463-15467, 2017.
[9] S. Wunscher, R. Abbel, J. Perelaer and U. S. Schubert, “Progress of alternative sintering approaches of inkjet-printed metal inks and their application for manufacturing of flexible electronic devices,” Journal of Materials Chemistry C, pp. 10232-10261, 2014.
[10] Y.-T. Kwon, Y.-I. Lee, S. Kin, K.-J. Lee and Y.-H. Choa, “Full densification of inkjet-printed copper conductive tracks on a flexible substrate utilizing a hydrogen plasma sintering,” Applied Surface Science, vol. 396, pp. 1239-1244, 2017.
[11] J.-J. Chen, G.-Q. Lin, Y. Wang, E. Sowade, R. R. Baumann and Z.-S. Feng, “Fabrication of conductive copper patterns using reactive inkjet printing followed by two-step electroless plating,” Applied Surface Science, vol. 396, pp. 202-207, 2017.
[12] H. Ning, R. Tao, Z. Fang, W. Cai, J. Chen, Y. Zhou, Z. Zhu, Z. Zeng, R. Yao, M. Xu, L. Wang, L. Lan and J. Peng, “Direct patterning of silver electrodes with 2.4 lm channel length,” Journal of Colloid and Interface Science, vol. 487, pp. 68-72, 2017.
[13] T. Ye, L. Jun, L. Kun, W. Hu, C. Ping, D. Ya-Hui, C. Zheng, L. Yun-Fei, W. Hao-Ran and D. Yu, “Inkjet-printed Ag grid combined with Ag nanowires to form a transparent hybrid electrode for organic electronics,” Organic Electronics, vol. 41, pp. 179-185, 2017.
[14] T.-H. Yang, Z.-L. Guo, Y.-M. Fu, Y.-T. Cheng, Y.-F. Song and P.-W. Wu, “A low temperature inkjet printing and filling process for low resistive silver TSV fabrication in a SU-8 substrate,” 30th IEEE International conference in Micro Electro Mechanical Systems (MEMS), 2017.
[15] J. Roh, H. Kim, M. Park, J. Kwak and C. Lee, “Improved electron injection in all-solution-processed n-type organic field-effect transistors with an inkjet-printed ZnO electron injection layer,” Applied Surface Science, vol. 420, pp. 100-104, 2017.
[16] K. Y. Mitra, C. Sternkiker, C. Martínez-Domingo, E. Sowade, E. Ramon, J. Carrabina, H. L. Comes and R. R. Baumann, “Inkjet printed metal insulator semiconductors (MIS) diodes for organic and flexible electronic application,” Flexible and Printed Electronics, vol. 2, no. 1, p. 015003, 2017.
[17] X. Guo, Y. Xu, S. Ogier, T. N. Ng, M. Caironi, A. Perinot, L. Li, J. Zhao, W. Tang, R. A. Sporea, A. Nejim, J. Carrabina, P. Cain and F. Yan, “Current Status and Opportunities of Organic Thin-Film Transistor Technologies,” IEEE Transactions on Electron Devices, vol. 54, no. 5, pp. 1906-1921, 2017.
[18] A. Perinot, P. Kshisagar, M. A. Malfindi, P. P. Pompa, R. Fiammengo and M. Caironi, “Direct-written polymer field-effect transistors operating at 20MHz,” Scientific Reports, vol. 6, pp. 1-9, 2016.
[19] L. Basiricò, P. Cosseddu, B. Faboni and A. Bonfiglio, “Inkjet printing of transparent, flexible, organic transistors,” Thin Solid Films, vol. 520, pp. 1291-1294, 2011.

 

 

Andrew Walla, RF Engineer, Successful Endeavours

So there has been some substantial change but we aren’t yet at the point where this type of Electronics Design and Manufacture has begun to significantly disrupt the mainstream industry. But I can imagine the day when some of what I do now can be printed and tested right now on my desk instead of having to go through PCB Design, PCB Manufacture and Electronics Prototyping first. Can’t wait for Printed Electronics to become mainstream.

Successful Endeavours specialise in Electronics Design and Embedded Software Development, focusing on products that are intended to be Made In Australia. Ray Keefe has developed market leading electronics products in Australia for more than 30 years. This post is Copyright © 2017 Successful Endeavours Pty Ltd.

 

 

Power Supply Specification

The idea for this post came from a discussion in IEEE Collabratec on how to design a Power Supply. The question of how to design a Power Supply seems innocuous enough until you really start to think back on past Power Supply designs. I was originally concerned that this was a student wanting someone else to do their coursework assignment for them but the discussion progressed into something quite useful. Here is what I posted after getting the following specification:

  • Output Voltage: -300VDC
  • Output current: 0.5-20mA
  • Tolerance: 30Volts
  • Input Voltage: 220-240 AC
Power Supply

Power Supply

Analysing Requirements

Hi …

is this project part of your course work?

The reason for this question is that the intent of coursework is to help you come to grips with what you are being taught and learn it from a practical perspective as well. Among other things, this helps a lot with retention.

I run a company that designs products for other people. I only employ graduate engineers who have demonstrated the capacity (though their academic results) and inclination (through their having done their own projects and learned how to use the teaching they have received) to do engineering and to be capable of quickly learning all the things they can’t teach in a course.

So if it is coursework, what subject is it part of?

Because if they want you to design a switching mode power supply, that is very different to an AC rectified transformer design.

You also need to be careful with a design assignment like this (coursework or a product that will be manufactured) because it is capable of killing you if you don’t use good safety practices.

I’ll assume your tolerance figure is +/-30V = +/-10% of -300VDC. So the voltage at its maximum excursion from 0V could be -330. And the maximum current is 20mA. This is 6.6W of power so it will get hot. And again, there is enough voltage to kill you.

If it is for a commercial product, then there are usually other constraints. Here are some of the questions I would be asking:

  • The input voltage range is specified as 220VAC to 240VAC but it is normal to allow for short term transients. So does the output voltage have to be clamped during mains transients?
  • Is soft start required?
  • How quickly must it respond to load transients?
  • What is the load and how much does it vary?
  • Does the input stage need to be designed so that it keeps harmonics and power factor under control (this is a legal requirement for some product types)?
  • Is there a maximum size?
  • What is the design life and/or MTBF (Mean Time Between Failure)?
  • Is fan forced convection allowed, and if so, is that even a good idea because of the MTBF or because it goes inside a sealed cabinet)?
  • What is the maximum temperature rise allowed on any of the outside surfaces?
  • What type of connections for the input and output voltages?
  • What has to happen if the output goes short circuit or open circuit (you had a minimum current of 0.5mA so is there a minimum external load and what is allowed to happen if that isn’t there)?
  • What is the environmental specification (0->70C, -20->85C, -40->85C etc)?
  • Is there a manufactured cost target?
  • Do you have to simulate it only, or are you building one and proving the performance?
  • Are there any special safety or EMC compliance requirements for this application?

And there are lots of other questions like this for a real product design.

So regardless of the reason for the design, understanding the intent of the exercise is important to delivering a satisfactory outcome.
This is one of the reasons engineering is not easy. We create the future. Others say that as well. But we also create the infrastructure and products that make a more advance future possible. And there are always lots of constraints.

I hope that has maybe encouraged you to think a bit deeper about the question. It is unlikely you will solve a problem you don’t fully understand. And an answer you don’t work through for yourself will probably not expand you understanding.

Successful Endeavours specialise in Electronics Design and Embedded Software Development, focusing on products that are intended to be Made In Australia. Ray Keefe has developed market leading electronics products in Australia for more than 30 years. This post is Copyright © 2017 Successful Endeavours Pty Ltd.