Language of Electronics: Tips to Maximize the Value of Digital Inkjet

Introduction

In this latest commentary, Rick Herrmann, Orbotech West’s inkjet expert, provides tips on how to take full advantage of your digital inkjet printers in PCB manufacturing, explaining how to maximize their performance, increase uptime while saving time and money, and provide high-quality boards.

richard_herrmann.jpgTips to Maximize the Value of Digital Inkjet Printers for PCB Manufacturing

by Rick Herrmann

In recent years, there has been a shift from conventional to additive PCB manufacturing. Unlike conventional silkscreen processes, digital inkjet printers can consistently and accurately produce even the most advanced legend designs at any manufacturing volume. Inkjet printers bring cost savings, require less energy, less labor, and reduce material and chemical waste. The missing link for most inkjet printer users is how to maximize the performance and reliability of the tool while saving money and time. Here are some tips to maximize the value of these versatile printers.

Uptime Is Critical
For most, this is an important factor—downtime means lost production and money. If uptime is a critical factor, choose an inkjet model with a proven track record for reliability and excellent customer service teams. You should also consider the technology; for example, LED curing is much more reliable than mercury lamp curing systems. UV-curable inks from a trusted vendor will be more reliable than hot melt or solvent-based inks.

Low Maintenance
Although digital inkjet printers have improved greatly over the years, it is still essential to follow the vendor-recommended maintenance procedures. No printer is maintenance-free; for example, we recommend various daily and weekly maintenance checks by the user. These maintenance checks take less than five minutes each and can help prevent unplanned downtime, maximizing the value of your printer.

Tool ‘Owners’
In our experience, companies are most successful when it's clear who is “in charge” of the inkjet printing process, maintenance, and any troubleshooting. With a lot of labor shifting in the U.S., it’s understandable if the same person isn’t responsible for all of these aspects, but having a small set of people “owning” the maintenance processes will typically increase the uptime of printers, avoiding the “but I thought you took care of it” issues that otherwise arise.

Printer Environment
Inkjet printer manufacturers provide specifications for physical printer environments. Many new owners mistakenly think these are “nice-to-haves” and not “must-haves.” A clean air, dust-free environment—along with temperature and humidity control—are all critical factors in keeping legend inkjet printers working efficiently, consistently, and accurately. Users sometimes find it difficult to justify the cost of meeting the environment specifications for a machine that is relatively low in cost; however, in the end, the investment is well worth the expense.

Printer Head Life Expectancy
This is a really important tip. The first and possibly most important thing to know about printer heads is that they don’t last forever. We find that many users are surprised by this, but it’s normal for the heads to wear out. They are a consumable item and probably the biggest cost associated with legend inkjet printers, but an ounce of prevention—or should I say maintenance—goes a long way to get the most from each printer head.

The length of time a printer head lasts depends on a number of factors, including reflected UV light, expired ink, the printer environment being out of specification, and more. Other factors include usage and quality demands. That said, the printer head life cycle is fairly predictable under consistent conditions.

With printer heads costing in the thousands of dollars (and most printers have two), it makes sense for the industry to shift to a proactive or predictive model for printer head replacements. Currently, most users evaluate printer head life based on time; however, there are many more considerations.

I liken it to brakes on a car: The frequency with which you replace your brakes will depend on what type of driver you are, whether you drive in the city or on the highway, whether you drive in snow and ice during the winter or are in a temperate climate all year round.

For printer heads, the best way to predict the best time to replace them is to consider the number of print cycles, as well as the ink type, panel size, and specific application. It equates to “predict and replace before failure.” Very simple. To go back to a car analogy, it’s like replacing your oil every six months or 10,000 miles. You don’t wait until your engine seizes to add or replace the oil.

Because printer heads represent a significant cost, it can be tempting to try to extend them for as long as possible in order to save money. But there are costs to doing so that are very real, although not as easy to quantify. A few examples:

  • Reworking a process means lost time and labor, and possibly missed deadlines.
  • Stripping UV legend ink is very difficult and can further damage materials.
  • Scrapped boards that cannot be reworked can represent a loss of $500–1,000 per board.
  • Being forced to fall back on the conventional silkscreen process can be cumbersome and wasteful.
  • Loss of customer trust could result in more rigorous verification processes, sampling, and customer audits. In extreme cases, you could lose the customer altogether.
  • Compensation to OEMs due to functional failures found after assembly may be required.

At some point in the future, technology will automatically inspect and assess the condition of printer head jets. But until this becomes a reality, regular visual inspection is necessary.

Because printer head life cycles are predictable, you can put processes in place to identify problems early before there is scrap. One method is to regularly print a known test print. I prefer to add a simple coupon to all boards as a simple visual check for the operators that doesn’t interrupt production.

We also recommend stocking a backup set of printer heads on site. This prevents unnecessary delays waiting for purchase approval and scheduling additional service visits when it is determined that the print heads need to be replaced. For instance, some printer heads have a shelf life of a few years.

Ink Condition
Adhering to the recommended shelf life and storage conditions for printer ink, as recommended by the ink vendor, is also key to maximizing the life of your printer and print heads. The printer manufacturers, ink manufacturers, and R&D teams all recommend replacing the ink in the system at regular intervals. This ensures there are no impurities, and the viscosity for optimum “jettability” is maintained.

Just like cars or other machinery, digital inkjet printers used for PCB manufacturing can be tremendous assets, but they must be maintained properly to save your team time and money and to protect your company’s reputation for providing quality boards.

I would recommend reaching out to your inkjet printer supplier if you have further questions or need help implementing any of these suggestions.

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2020

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