Setting Up Your Printer

Getting started with printing circuits is a relatively simple and inexpensive process. There are three main things you will need; an inkjet printer, conductive ink, and a substrate.

When selecting a printer, almost any inkjet printer will work. Some researchers claim that it is best to use a piezo-driven printer rather than a thermal-driven one as it is less likely to alter the structure and properties of the conductive ink.[1] It doesn’t need to have fancy touchscreen controls or wireless connectivity. Just look for a cheap printer that you would feel comfortable taking apart and modifying. Studies have shown that Brother Co. printers are the preferred option when it comes to printing circuits due to their nozzles releasing higher volumes of ink. [2] More ink on the page means that there is a better chance of a solid connection or trace being made. The projects on this blog will use a Brother MFC-J450DW. This model was chosen mostly due to the fact that it was the cheapest on Amazon for about $80 at the time of writing. It is also recommended that you purchase empty refillable ink cartridges that are compatible with your model of printer. Trying to reuse the standard ink cartridges may end up contaminating your conductive ink and lead to poor connections. These refillable cartridges can range anywhere from $5-20 depending on the model of printer they are for.

Next you will need the ink. There are many properties such as viscosity, surface tension, volatility, and particle size that need to be taken into consideration for choosing a suitable ink. Luckily, an extensive amount of research has already been done on this and there is a clear winner. Silver nanoparticle ink, part number NBSIJ-MU01, from Mitsubishi Paper Mill works the best for most applications.[3] This ink can be purchased from Diamond-Jet for $340.00 per 100 ml.[4] Admittedly, this does sound like a daunting price at first. However, most conventional ink cartridges only contain between 10 – 15 ml of ink inside of them. So overall the price per ml isn’t that much more expensive. With a 100 ml of silver nanoparticle ink you will be able to print hundreds of circuits.

Another benefit of the NBSIJ-MU01 ink which helps justify the price is that it is chemically sintered. Sintering is the process which take a powdered material or solution and transform it into a solid. With inkjet printing the printer does not print continuous lines. The printer prints many small drops of ink. The sintering process helps combine the silver nanoparticles in these drops together thus creating a complete circuit. Traditionally, the inks would have to be sintered or “baked” in an oven for a few hours so that the solidification process would take place.[5] Chemically sintered silver nanoparticles are dissolved in a special solvent that allows for the reaction to take place just seconds after it is printed.[2] This dramatically reduces the time it takes to prototype a circuit.  

The only thing left is the substrate. Choosing a proper substrate is important because it dictates how well the ink will adhere and last. There can be a lot of experimentation still done with the substrates as some may work better in certain situations than others. Some good baseline substrates are resin coated paper, white and transparent PET film, inkjet paper, and glossy photo paper.[6]

Now hook up your printer, fill and insert your ink cartridges, and start printing!

References

[1]          M. M. Tentzeris, “Inkjet-Printed Nanotechnology-Enabled Zero-Power Wireless Sensor Nodes for Internet-of-Things (IoT) and M2M Applications,” ATHENA Research Group, School of ECE , Georgia Institute of Technology, Atlanta, GA, 30332-250, USA.

[2]          Y. Kawahara, S. Hodges, B. S. Cook, C. Zhang, and G. D. Abowd, “Instant inkjet circuits: lab-based inkjet printing to support rapid prototyping of UbiComp devices,” 2013, p. 363.

[3]          P. H. King, J. Scanlan, and A. Sobester, “From Radiosonde To Papersonde: The Use of Conductive Inkjet Printing in the Massive Atmospheric Volume Instrumentation System (MAVIS) Project,” 2015.

[4]          “NBSIJ - Silver Nanoparticle Ink - 100ml-1,” Mitsubishi Imaging (MPM), Inc. [Online]. Available: http://diamond-jet.com/silvernanoparticleink-2.aspx. [Accessed: 28-May-2015].

[5]          T. Falat, B. Platek, and J. Felba, “Sintering process of silver nanoparticles in ink-jet printed conductive microstructures - Molecular dynamics approach,” 2012, pp. 1/5–5/5.

[6]          Y. Kawahara, S. Hodges, N.-W. Gong, S. Olberding, and J. Steimle, “Building Functional Prototypes Using Conductive Inkjet Printing,” IEEE Pervasive Comput., vol. 13, no. 3, pp. 30–38, Jul. 2014.