An interview with Shane Ketcham, Applications Engineering Manager at Sono-Tek Corporation, regarding new breakthrough EMI shielding spray coating technologyShane Ketcham has been a member of Sono-Tek’s Application Engineering team since 2011, specializing in electronics, alternative energy, and semiconductor spray coating applications using ultrasonic nozzle technology.
How did Sono-Tek first find out about the EMI shielding process using sprayed silver inks?
Sprayable EMI chemistries have been out for many years now, and we were approached by several ink suppliers starting in 2016 for a better way to spray. We have seen that both the ink suppliers and customers had the same underlying issues, other methods of spraying were just not cutting it, and they were looking for a spaying technology that could deliver consistent, repeatable results in a production environment. Luckily, we have had decades of experience with applications in alternative energy where we are often coating challenging materials and medical implantables in which consistent results are required.
What makes your technology different?
Easy – a completely ultrasonically active atomizer. Pumping through Teflon tubing is easy. It is what happens when materials go through nozzles and are exposed to air where you start to have trouble. Our technology does not suffer from the shortcomings of spray technologies like jetting, air atomized spray, or other dispense methods. Due to the constant ultrasonic energy and unrestricted path through the atomizer, our technology is non-clogging and does not change spray characteristics over time due to material build up. Ultrasonics give the added benefit of a repeatable droplet size and liquid flow for a very consistent coating from part to part and day to day.
How much momentum have you seen in the past 12 months for the feasibility of this new process?
We’ve seen quite a bit of interest from large companies who are looking into alternatives to sputtering the EMI layers on. Sputtering works very well and is established; however, inline spraying with our ultrasonic technology is roughly 10X less expensive than the capital cost for the same parts per hour with a significant reduction to floor space. This is driving many OSATs and other users of these coatings to look further into next-generation technologies like ours.
In addition to coating ICs, what other applications can EMI coatings be used for?
Because we are substrate agnostic, we can coat just about anything. Most of the interest so far has been for small ICs that often are mounted to a BGA, but we can also spray coat the inside of large panels for automotive applications, various electronics housings, and any other 2- or 3D substrates. For the larger 3D applications, wetypically use our OmniBot system, which is based on a 6-axis robot.
What does Sono-Tek bring to the table for this process that is beneficial over other spray technologies?
We are confident that our capital equipment is significantly more economical and has a smaller footprint than sputtering. With regards to other spray coating technologies, we will have a similar capital cost but, based on experience, we will be much more repeatable,lower maintenance, and will have significantly less waste and overspray due to the very high transfer efficiency of our AccuMistnozzle.
Our applications engineering team has also worked directly with ink developers to understand the requirements for optimal spray characteristics, including solids dispersion, temperature, drying, and depositing multiple layers. Our equipment is easily optimized for these coatings and with our current knowledge base we can quickly get customers to what they need in a coating.
What are your equipment offerings for EMI spray shielding?
Our tabletop and standalone XYZ motion system, the ExactaCoat is a great fit for low-volume or R&D coatings. The FlexiCoat platform is an inline production system with conveyor as well as many options to suit the needs of full scale manufacturing. This is a proven platform that has been used in high-volume manufacturing for more than 10 years. Our 6-axis robot, the OmniBot, is the right fit for large 3D parts that need to be coated. The ability to customize machine options, quickly adjust process parameters, and easily program coating recipes make these tools a great solution. Sono-Tek is always engineering solutions that are scalable so that as manufacturers scale up processes, we are ready to meet their expanding needs.
How do you see EMI expanding in the future?
I believe that EMI coating is on the precipice and a few major companies in the industry will be switching to spray coating in the next 18 months. Once a few start switching over, the industry will move quickly. Luckily, we are in a position to be able to build systems quickly to meet the demand.
What would you say to someone who is cautious about moving to a new process?
They should speak to an EMI ink provider who can show them proof.Additionally, they should look for technical papers such as the one posted on our website (https://www.sono-tek.com/industry/semiconductor/emi-shielding) titled “EMI Shielding Effectiveness Study of a 3D Printed Antenna in Package (AiP)” by Dr. Reena Dahle et. al., Division of Engineering Programs, SUNY New Paltz. If they’re still cautious, they can get parts tested at Sono-tek’s state-of-the-art lab, or even get our ExactaCoat and do conduct their own R&D.