printconnect
From Circular Electronics to Industrial Performance - The Story Behind SECTR

Host: Rob Penhallow
Guest: Léonardo Giacomini, Printed Electronics Product Manager, VFP Ink Technologies

EDITED PUBLICATION TRANSCRIPT - BASED ON THE SUPPLIED FINAL-EPISODE TRANSCRIPT

ROB PENHALLOW:
Welcome to printconnect, the podcast from Specialist Printing Worldwide. In an earlier episode, we spoke with Jeremy Flageul, Sales Director at VFP Ink Technologies, about piezoelectric inks.

Today we're returning to VFP for a different story: how work on recyclable paper-based electronics led to SECTR, a conductive silver ink designed for industrial use. How do you balance low-temperature processing, electrical performance and the practical demands of production?

Joining me to explore that is Léonardo Giacomini, Printed Electronics Product Manager at VFP Ink Technologies.

Léonardo, welcome to printconnect. So let's start at the beginning. How did SECTR come about?

LÉONARDO GIACOMINI:
Hello Bob, thank you for having me. SECTR was born in a different context from our traditional development projects. It was part of a European project called CircEl-Paper, where the objective was to explore new approaches to developing printed electronic devices on paper, while also taking their end of life and recyclability into consideration.

So this is the thinking that led to the development of SECTR.

ROB PENHALLOW:
Why was paper chosen as a substrate for the electronics in CircEl-Paper?

LÉONARDO GIACOMINI:
Mainly because paper is particularly interesting. It's widely available, lightweight and already part of well-established recycling streams.

However, printing electronics on paper also introduces new constraints. Unlike plastic substrates, paper does not tolerate high processing temperatures very well. This means that developing materials capable of achieving the required performance at low curing temperatures is a challenge.

ROB PENHALLOW:
And so what changes when you print a conductive circuit on paper rather than plastic film?

LÉONARDO GIACOMINI:
The printing process is quite the same. The results can also be achieved through the same process. It's more the subsequent processes that can present a challenge, particularly soldering and other issues along the production chain.

ROB PENHALLOW:
And so the CircEl-Paper project isn't only about the performance of the ink, then. Is it more about end of life or the ink itself?

LÉONARDO GIACOMINI:
Yes, the requirements of this project made the ink particularly interesting. It wasn't only about demonstrating that we could print a conductive circuit on paper. That is quite easy, let's say.

But going through the whole manufacturing process to the end of life of the device, that was the challenge. So working on materials, printing processes, electrical performance, but also, and one of the most important parts, recyclability.

ROB PENHALLOW:
Okay, so let's move from the research and the brief to what came out of it. In practical terms, what is SECTR?

LÉONARDO GIACOMINI:
SECTR is a two-component conductive ink designed particularly for the screen printing process. It can be used to produce conductive tracks on a variety of substrates, including paper, PET, polyimide and PVC.

The objective was to develop a formulation combining several properties that can sometimes be difficult to achieve together: good conductivity, relatively low-temperature curing and strong resistance to chemical and thermal stress. That's what SECTR stands for: chemically and thermally resistant.

ROB PENHALLOW:
Okay, so you mentioned low-temperature curing. Why is this such an important feature?

LÉONARDO GIACOMINI:
It's important for mainly two reasons. The first is compatibility with heat-sensitive substrates. With SECTR, the curing process can start at 50°C and go up to 120°C, depending on the substrate and process, of course taking into consideration the time-temperature correlation.

So 50°C nowadays is a really low curing temperature, and it was developed for new substrates that are very thin and could move during the process.

The second reason concerns the energy required for the process itself. Reducing the curing temperature can help lower the energy consumption associated with this stage and can also make it easier to integrate into industrial processes, such as soldering.

ROB PENHALLOW:
Okay, so from a printer's perspective, what trade-offs are there between temperature, dwell time and the conductivity they're looking for?

LÉONARDO GIACOMINI:
Yes, of course. If you lower your temperature, your conductivity will not be as good as at a higher temperature. But the idea of starting at 50°C is that you can already have good conductivity to produce tracks and connections with no issue.

At 120°C, you have better conductivity and lower resistivity. But if you start at 50°C and go up to 120°C, you maintain the adhesion, which is really important for this kind of ink, as well as the performance.

Of course, it depends on curing time and temperature, but you have interesting conductivity even at 50°C. On today's market, we could say that's a benchmark.

ROB PENHALLOW:
And of course, low-temperature curing is useful, but the circuit still has to perform, like you say. So what resistance can SECTR achieve under the conditions you're talking about? And is there anything else that you have to prove for industrial use?

LÉONARDO GIACOMINI:
Yes, with SECTR, at 120°C we can achieve a resistivity of 10 milliohms per square per mil, which is very low resistivity and can give you higher conductivity.

But like I said before, resistivity performance is mainly determined by curing temperature and curing time. So if you have a delicate substrate and you have time to cure, SECTR is one of your options for this kind of process.

If you have less time and your substrate can withstand a higher temperature, the chemical resistance this ink can provide will also be an important consideration for your specific project.

ROB PENHALLOW:
So now SECTR has an environmental dimension built into its formulation. Can you tell us a bit more about that?

LÉONARDO GIACOMINI:
Yes, this dimension was part of the specifications from the very beginning of the development. SECTR is a non-CMR formulation. Non-CMR refers to carcinogenic, mutagenic and reprotoxic classifications, and this formulation avoids those classifications. For this project, we also incorporated bio-based raw materials.

However, it's important for us not to limit the environmental question only to the composition of the ink. Through the CircEl-Paper project, we worked on a much broader approach: the substrate, the curing temperature, the materials used and, above all, what happens to the printed device at the end of its life. So this was one of the key points for this development.

This project allowed us to go beyond our formulation in the lab, because SECTR was integrated into printed electronic demonstrators on paper. The idea was to study their behaviour from a recyclability perspective.

This is an important point. When you talk about more responsible electronics, simply replacing one material with another is not enough. We need to consider the complete system, the complete environment and how it behaves at the end of its life.

ROB PENHALLOW:
And SECTR was born from a European research project, like you've spoken about, and now it's become a genuine industrial solution. How do you make the transition from one to the other?

LÉONARDO GIACOMINI:
This is probably one of the most interesting aspects of the project for VFP specifically. A collaborative project such as CircEl-Paper allowed us to explore, test and evaluate a technology by bringing together different areas of expertise.

Sometimes, when we as industrial manufacturers develop something for one specific process, we can improve our technology through that project. In the end, we can create benefits for other applications, not only the one we were specifically discussing.

ROB PENHALLOW:
And so where do you see the strongest applications for SECTR today?

LÉONARDO GIACOMINI:
Today it would be the automotive area, especially when we talk about high temperatures, and also the aerospace market. Those two markets have advanced technologies and demanding requirements.

So when you have a chemically and thermally resistant ink, those two markets are key opportunities for this kind of new ink. And when you talk about recyclability, the automotive sector is also one of the key areas.

ROB PENHALLOW:
And if you were summing up what SECTR represents for VFP in one sentence, what would that be?

LÉONARDO GIACOMINI:
Paper was the starting point, but it's not the limit.

ROB PENHALLOW:
Okay. And where do you see the biggest opportunity for this technology next?

LÉONARDO GIACOMINI:
The possibilities are quite broad, like I said before, but mainly printed sensors, flexible circuits and connected devices. Today smart packaging is one of the newer markets, and NFC antennas as well.

It's compatible with different substrates, which also means SECTR can be considered for applications beyond paper-based electronics. That is the beauty of SECTR. You can use it not only for standard projects, but also for high-demand technological processes. So it can be used across a wide range of markets.

ROB PENHALLOW - OUTRO:
I think one of the really interesting things about this story is just how far a research project can take you. SECTR started with a fairly specific challenge: developing conductive inks for recyclable paper-based electronics. But as we've heard, the potential applications go well beyond that.

And that's what makes printed electronics such an interesting space to watch. You never quite know where the next innovation might lead.

A big thank you to Léonardo Giacomini from VFP Ink Technologies for joining me today, and thank you to you for listening. If you enjoyed the conversation, do check out our other episodes of printconnect wherever you get your podcasts.

Until next time, thanks for listening.