Lopec Show- Inkjet Technology Review and a question we all have wondered why are Printed Circuit Boards typically green?

An article written by Holly Steedman, IST INTECH

Printing Electronics and inkjet is not a new application. When I worked for a Printhead manufacturer in the early 2010s, purchasing development kits for this application was a hot topic, and I installed many in these applications wondering how this would progress. At the time, they bought one head and had come with lots of questions, so typically, it was handed over to the application department pretty fast. That's where we, as applications engineers, got involved and had fun. We could support them and learn at the same time.

One of the drives at the time was legend printing. There was an increasing need to identify each panel and PCB uniquely. Screen printing was not ideal, so other methods, like adding labels to the panels and hand stamping the individual boards, were used. So, at the time, digital printing was considered an ideal way to improve those time-consuming and costly additional processes. Piezoelectric printheads were preferred because they could print fine conductive traces and complex circuit patterns with high drop precision control and high-resolution capabilities.

Today, you can see how it has progressed from engineers researching the possibilities to full-scale production machines in various applications like solder masks and legend printing. I visited Lopec to catch up on what's new and how inkjet is progressing as a manufacturing process in this market. While it is clear screen printing is still a dominant process in this application- for good reasons! The advantages of inkjets are slowly becoming more ingrained in this world, and the key topic I picked up is enabling. How do we enable more people to implement inkjet? How do we remove the barriers we face in this industry?  We have faced challenges before, but each application has different aspects. Here, the challenges are extremely demanding compared to standard graphics applications. We are talking about micron-level precision and jetting functional fluids requiring complex fluid management. I saw many examples of companies creating products and technologies that were looking to solve problems.

The first company that has become an inkjet specialist in this area of machine building is Notion Systems- Speaking with Kai Keller; you can feel the passion for educating this industry on how to use inkjet to create more efficient and sustainable production processes they have been developing for this market since 2015 - their N jet printer solder mask (think the green colour on a printed circuit board) replaces three steps in the production process a perfect advertisement for inkjet conversion. It seems like a no-brainer, but an interesting topic came up with inkjet technology. You can print the solder mask only where needed, saving on wastage. Still, this looks very different from what you commonly associate with a PCB, so it takes time to be accepted as it challenges the norms. But if you need a good reference about inkjet applications you come in touch with daily, they had a superb sample of a pocketbook e-reader featuring their pixel printing technology.

Inkatronic from Austria, which provides Inkjet Solution Engineering, launched its new Low Volume Lab Tank Ink Delivery System. They developed the system after feedback that they received about one of the issues when testing inkjet fluids, especially high-cost formulations was the amount of fluid needed for a test. This system can provide stable circulation of fluids with a minimum of 30ml and supports all kinds of piezo printheads it has two external pressure and temperature sensors that can be integrated close to the printhead to analyse pressure changes caused by restricting factors in the flow path through the printhead - chatting to Mikael Boeder; they want to deliver the components needed to speed up integration and testing and enable more development in these areas. They see a bright future for inkjet with the right tools and knowledge-sharing

ImageXpert launched their new PrintPod printer, a compact benchtop system that gives flexibility compared to other systems designed for material formulation development, like the Dimatix Materials Printer DMP, which is restricted to the Dimatix head. With the PrintPod, any combination of head and drive electronics can be used, and ImageXperts drop-watching technology can be integrated- that, to me, is a really interesting approach as it gives such flexibility and no limitations in development.

SÜSS MicroTec from Germany was also showcasing a new show launch version of their prototype printer LP50. Featuring a new printhead configuration with...you guessed it, Epson. The collaboration between SÜSS and Epson means the system now adopts the Epson Mems I3200 Series printheads to print two fluids simultaneously with separate pressure systems for each fluid. The unique feature they were quoting was the print head/ink delivery/drying unit, which is a single piece that can be removed and replaced while that one is cleaned offline.

SÜSS MicroTec Printer

I had a great conversation with Milena Frtiz from SAT Electronic. She became the CEO of the family business 2 years ago, which is a hot topic in Germany as many traditional family-owned companies do not have the next generation willing to take over anymore. This is leading to many midsize (Mittelstand) companies being sold. She was full of fresh energy and knowledge for this application. SAT Electronic is a Microcraft product distributor, offering scalable systems for easier upscaling from small lab  to production systems featuring mainly Konica Minolta and Epson printhead options. Microcraft is a Japanese company and one of the early players in releasing a drop-on-demand printer for Printed Electronics in the early 2000s.

Along the way, there were some great examples of the combination of screen, dispensing, and inkjet printing also- utilising the benefits of different application methods- Ceradrop, the printer manufacturer from France, showed an interesting example of a resonator where the ceramic structure was printed with inkjet, and the wire connectors with high viscosity with a dispensing method- Could this be an application of inkjet with high viscosity capable printheads? 

Ceradrop Printer

Prize for great product samples goes to CCL Design from my region, Stuttgart, showed great examples of utilising the benefits of the opacity of screen-printing inks with the variable digital printing data in their home appliance application panels. The products are designed and printed in-house.

CCL Print samples Screen_digital

So, before I finish- the question we all want to ask-why are PCBS commonly green?

It is widely considered that PCBs are commonly green due to their early applications being military applications. Green is commonly used in military equipment, so they were made green to match these standards. 

It was clear visiting the event that inkjet is increasing its presence in the printing electronics world as more exhibitors and visitors from the Inkjet community attended. There is definitely much to learn, and it is well worth visiting if you want to engage actively. But watch out, Lopec. I hear the new kid on the block is gaining momentum, and after visiting Tech Blick last year, I can confirm that it has a different vibe and energy than Lopec. So if you did not catch Lopec and want to see for yourself maybe I will see you in Berlin or Boston.

For more information on any of this content please contact Holly Steedman directly.