AGFA: From Film to Inkjet Solder Mask

Estimated reading time: 12 minutes

The productronica show was indeed filled with new technology and it was great to meet with people and learn about it. This is precisely how I met AGFA’s Frank Louwet, who filled me in on the Dipamat inkjet solder mask they have been developing. It seemed an odd choice to go from film to solder mask, but as Frank explained, it makes perfect sense.

Patty Goldman: Frank, please tell our readers about AGFA, and then we’ll get to the interesting new product you want to talk about.

Frank Louwet: I'm the business manager for Advanced Coating and Chemicals, within AGFA Specialty Products. AC&C develops, produces and sells materials for the PCB industry and for printed electronics. We are best known for our phototooling film, Idealine, which is the silver halide film. That's for PCBs, and for the printed electronics it's Orgacon inks based on conducting polymers and silver nanoparticles. These are the main product groups that we have.

Goldman: I understand that you're moving into some new markets, or changing products.

Louwet: Yes. The world is becoming digital. The days of film are still going well for us, but we can see that it will decline in the future. With the background that we have in inkjet and digital printing as a graphics company, we decided to move into digital fabrication, specifically for the PCB industry. We started about five years ago developing Dipamat marking inks or inkjet legend inks for PCBs. In the meantime, we have white, black, yellow, and a flexible one. The next step that we took was etch-resist inks to pattern the copper, basically.

Goldman: You've gone from films to inks, which is really a different type of product.

Louwet: It's different, but it's for the same market. We know inkjet. It is in our genes at AGFA. There's an InPrint exhibition next door, and our colleagues in graphics have their stand there, explaining about their inkjet solutions for all kinds of applications. From that background know-how, we develop the Dipamat inkjet inks for the PCB industry.

Goldman: How is that going?

Louwet: It's very exciting. You never know how the industry will react. We see that it's going very well. There’s a big pull from the market to test and see how it performs.

Goldman: So, this is the inkjet solder mask?

Louwet: Yes, what we have in front of us is a PCB with solder mask that was inkjet printed. One has nickel-gold finish and the other one immersion tin. At productronica two years ago, we announced that we were going to start developing this solder mask. Last year, at electronica, we showed a prototype, and this year we can show an almost finished product! So, the inkjet solder mask board that is in front of you meets all the IPC norms. It is UL V0, and passes the ASTM outgassing standard.

It passed also the more stringent automotive tests: 1,000 hours conservation at 150°C and the extensive temperature cycle tests.

Louwet: It's taking away a little part of our existing market, because now we're selling film to image the solder mask, but it's better that we do it than not.

Goldman: Right, otherwise somebody else will, because things never quite disappear, but they do diminish.

Louwet: It's a big advantage for the industry. In the traditional way, it is first curtain coat (or spray or screen print), dry, then coat the other side, dry, then go to the imaging area using film (which also has to be prepared), or go to the LDI, and then finally you have the development step to come to the solder mask image.

Goldman: Which makes for quite a few steps.

Louwet: A lot of steps! And this can be done with one printer on a few square meters; it's very compact. Also, what you see here is still a bit what is called “old school.” It’s in some way similar to what is done today with solder mask—cover the entire area with the same ink thickness. But if you think digitally you can apply the ink only where it is necessary for the functional requirement, so some areas need only a very thin, or no coating, and other areas need a thicker layer.

Goldman: Rather than coating everything with solder mask, which is very wasteful and time consuming.

Louwet: And on top of that, coating solder mask into the drill holes is at the top of the list of yield issues. Digital inkjet will print around the drill hole.

Goldman: No sense protecting what doesn’t need protecting, like bare laminate. What is the resolution that you're able to achieve with the inkjet?

Louwet: We have been printing at 100 micrometers, or four mils. But 75 mm is also possible.

Goldman: Is that a function of the inkjet printer, as opposed to your ink?

Louwet: Yes, it's a function of the inkjet head. There is an evolution to smaller and smaller droplet sizes. Typically, for soldermask you'll use the smallest droplet size, which is a few picoliter. Konica Minolta, Fuji Samba or Kyocera all have really small droplet size heads, and that allows you to print very narrow features.

Goldman: Have you developed a primary resist, say for electroplating?

Louwet: The final stage was a solder mask. We started with the legend ink, and the development in between was indeed etch or plating resist. So that's something that is available, and that we are also rolling out commercially. The etch resist has already been available since last year. This is not going so fast in the PCB industry because there's big competition of LDI for innerlayers. There is a resolution limitation, I would say, to inkjet technology for that part. But we see a lot of traction in metal etching, in die cutting, in decoration of metals, etc. There are a lot of industries that etch metal, and you can also do this digitally. You don't need very high-end inkjet printers for that, you can often use a graphic type printer. We're selling already etch resist for those kinds of applications.

Goldman: It's interesting that people I talk to here are from many industries. I always think it’s just PCB. But everybody's into something else also, which is good. So the solder mask here is green. I know sometimes people want other colors.

Louwet: Green is the big one. Some people say it's too shiny or too matte, or they don't like the type of green. We are also working on other colors and next year we expect to have black, white and a flexible solder mask.

Goldman: How is the white one coming along? I always hear there is trouble with white, keeping it white.

Louwet: We’ve built quite a bit of knowledge with the white legend Ink. From there we have a of base for the solder mask. In the beginning we indeed had some problems with yellowing of our legend materials. But, in the meantime, we have our fourth-generation of white legend ink, so we learned a lot from that.

Goldman: Are your customers receiving this favorably?

Louwet: Yes. You need two to tango, right? This is the ink, but you also need a printer and the printing strategy (software). Printing strategy is how you build up the solder mask layer by layer to obtain optimal functionality. Printer partners are very important. Together we go to customers. Via a three-way cooperation we build confidence in the market.

Goldman: You can’t work with just one printer company. You must work with all of them, I would think.

Louwet: We are a materials provider, so we do not provide the hardware for it. We are indeed cooperating with all the inkjet printer manufacturers. You will see if you walk around the booths, MicroCraft, Orbotech, Notion, Adeon and Meyer Burger are all printing with our Dipamat inks.

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