At NovaCentrix, we love working on projects that present real technical challenges with collaborators who think creatively and work smart. We have worked on many rewarding projects with both small research groups and individual researchers up to large multi-national technology companies. Working in printed electronics means exposure to many innovations – as the prints end up in an ever-growing number of devices (and it’s important to keep on top of process technology know-how). It can feel overwhelming to consider all the necessary details for creating a valuable and innovative new device, so I’m hoping that this post can help put us onto the path of success.
As a company, we bring many years of experience in printed electronics and a strong position in developing and understanding the latest techniques. I took some time to chat with one of our inks team experts (pictured) to talk about how an existing ink, or new ink, may be incorporated into a customer’s printing process. I’ve done so to build on the foundation laid by Rudy in his printing post, which I highly recommend reading [link]. I also recommend clicking through our Metalon Conductive Inks FAQ page which contains a lot of useful info [link].
I chatted with Senior Scientist Dr. Ron Dass before the new year about some of his experiences with inks that help our customers innovate and create value. The transcript has been edited for clarity.
HC: Ron, thanks for your time, I know that early on in any customer engagement you’ve made a practice of requesting that the customer consider a number of questions to “set the table” to best help them reach their goals. I’ve copied those questions here:
- What is your preferred print method and why?
- At what speed (m/min) or throughput (prints/hour) will the ink be printed?
- On what type of substrate (or surface) will the ink be printed? Do you have any adhesion requirements for your printed features on your target substrate (or surface)?
- At what temperature and time will the ink be cured?
- What is the desired wet/dry thickness (µm) of your printed features?
- What are your target sheet resistance values (mΩ/□) for your printed features?
- What is the size of the smallest feature (µm or mm) you desire to print? What is the size of the smallest gap within your printed pattern?
- Do you have any solvent resistance or scratch resistance requirements for your printed features (for example, resistance to ethanol, isopropyl alcohol, water, etc.)?
- Do you have special objectives to produce after curing, such as reflective and electrically-conducting print features on non-textured surfaces, solderability, etc.?
- Do you have a specific change/improvement targeted based on current operations?
... It’s important for the customer to take time to consider these questions and answer them to their best ability. Can you talk about an experience when the answer to one or a few of these questions emerged as a key part of the customer project?
RD: Thanks Harry, yes, it is almost always a key part of the project. The answers help us serve the customer since they give clear guidelines, but it also reveals the level of experience the customer has, from a new student researcher up to large corporations. We are happy to work anywhere along that range of experience and we have had rewarding projects come from both places.
As you know, I have been helping our team develop a catalog of different silver inks for flexographic printing. These inks have reached a level of maturity where we have had them on the market for a few years now while at the same time we continue to make modifications and develop them according to customer needs. Flexo has been a very attractive area in printed electronics because of the scale it can achieve. We have had customer projects where we developed silver ink capable of 20 m/min print speed or even up to 200 m/min print speed. Knowing the production speed as early as possible is very important. Knowing the speed early means we can narrow down the number of possible ink formulations we can test and we can narrow down more quickly.
Thinking about the form of the silver is also important. Nanoparticle silver compared with flake silver will sinter and cure differently. These and other factors influence the leveling and spreading of the ink and the dry thickness of the print. Of course, to get good print quality with fine features, that is not trivial and we work together with the customer to make the ink and the overall process fit based on their requirements and answers to the questions I ask at the outset.
HC: That’s great insight. Can you say more about what helps make a project successful with flexographic printing for printed electronics applications?
RD: With the answers to the initial questions, we can get into identifying or developing an ink and a process that will work for the customer. One big part of getting the ink and the process right is the chemistry and how that is monitored.
We know from experience that the temperature and humidity in the printing area are critical. It is important to be able to monitor the pH of the ink and we have even developed ways to control the pH within the equipment together with some customers. Any time we are sending an ink to a customer, whether it is a few small vials or several kilograms of ink and regardless if it is a new development project or a recurring order, I always make sure to communicate and enclose ink handling and storage instructions and documents.
Since we are often doing relatively large-scale prints in a roll-to-roll format with flexo, getting the ink and the process correct and with precision is critical. If you think about it in relation to screen printing, where we also do sell a lot of ink, for flexo you cannot simply stop and clean the screen and try a new small batch. The web will keep moving!
I mentioned how important humidity is to getting reproduceable prints at large scale. Helping customers implement a simple spot humidification set up in their printing area has proven to be the breakthrough needed for a few process development projects. The equipment can be quite simple and inexpensive or it can be integrated with continuous monitoring and control depending on the customer needs. A facility running in Southeast Asia in the summer will have very different temperature and humidity than one in central Europe.
HC: Definitely! With some of these process challenges with flexo, there is a big payoff on the flipside, like the huge scale that you can achieve. We can help customers incorporate the latest methods and materials, and capture that value and to deliver it for the latest technology products. Can you talk about how our and our customer’s insight or strategic thinking serves the market?
RD: Sure, as you might expect, things tend to go more smoothly if there are significant resources to call on when developing something new. A blank check can buy a lot, in other words. That situation is, as you also might expect, not common!
Being resourceful and thinking creatively are often even more important than writing a check. A new ink and process starting from small demonstration scale, with a hand proofer, up to full production can reasonably take more than a year. I won’t divulge any detail on customer work, but I have enjoyed making progress on a new flexo ink where we started with just printing from a hand proofer and are taking it all the way to a large format printer that’s 2-stories tall!
While the communication on that project sometimes had delays, I have been happy to be patient because our partners are meticulous in their documentation and provide a full report on the printing results that they see with the inks that we send to them. Communicating clearly and keeping thorough records for us and our partners is critical. While we don’t have large format flexo equipment two-stories tall in our warehouse, our partner doesn’t have the ink production and development facilities that we have. So, we have to communicate what we are each working on in as much detail as possible.
And I get satisfaction from working on more involved development projects. I appreciate the chances that I get to serve the customer. I’m not here to do a quick sale. A large order is nice but I’m all about ensuring the customer has success by making sure the ink is going to work for their application.
HC: That’s great insight, good communication between team members on a project is key to making things successful. Also, integrating knowledge to develop a new process has an important time dimension. In light of that, how do you think about integrating knowledge across team members who are in different places? We’ve talked about how much clear and timely communication helps.
RD: Yes, the communication is really key. We are serving customers in different parts of the world so we have to be clear in our message and show the data. This year the pandemic has made face-to-face interactions pretty much impossible. So, it’s important to have established methods of communication that work, or to be able to establish good communication over email and videoconference.
I know for the Apps team it has been quite a change from before when customer visits and travel to events was routine. For the development work with the Inks team, I’m pleased with the progress we’ve been able to make on projects with our customers. In spite of the challenges this year, I feel like we have done the work to stay up-to-date and educated on process technologies and can still be effective in serving our customers.
It is particularly rewarding to learn about the process beyond just the ink and that only happens when the communication is clear. Some of our best collaborators have become our advocates in the market and bring in other customers after we have demonstrated our process capabilities on their printing equipment.
HC: That’s great, thanks again Ron! It’s always rewarding to see the results from hard work. Can you share something that’s exciting for you thinking about the future of functional and conductive inks?
RD: Without directly talking about project details that must remain secret, I will say that I particularly feel good when working on biomedical and energy sector projects. It is very exciting because we can see our inks working in products that have a positive effect on people’s everyday lives.