Issue link: https://iconnect007.uberflip.com/i/1535414
MAY 2025 I PCB007 MAGAZINE 25 We now have sev- eral designed for direct image printers and have extended shelf life. Now, anyone with a newer DI printer can image 15–25-micron lines and spaces; but there are many challenges to the HDI–SLP–mSAP or sub- 25-micron lines and space resist platforms when pre-cleaning and applying resist to ultra-thin copper foil on ultra-thin composite material. e han- dling and transporting of these thin compos- ites through the various chemical processes is extremely challenging—surviving flash etch- ing for 10–15-micron lines with an isotropic etchant. Testing the resists at established pack- aging facilities is easy. You give them the resist and a marked-up TDS (technical data sheet), and they are making live product panels the next day. ey have all the equipment and proper environments: conveyorized chemical polish pre-clean lines, projection printers, vac- uum lamination, and super clean print rooms. PCB shops are not set up with that equipment set, but some are getting there. Are new resist products addressing sustain- ability at all? Krick: We do have a few situations where some customers have switched to Eternal photore- sist alone and saw an increase in yields, result- ing in less overall usage. It is a multidimen- sional process, but I think there are situations where we can help a customer from a sustain- ability perspective. What advice would you give to PCB manu- facturers looking to optimize their photoresist process and reduce the likelihood of defects in their production lines? Krick: Invest where you can. Imaging is the heart and soul of your shop. Sure, you can get away with a lot with older technology types, but in the modern world, quality and techno- logical demands continue to rise and will only continue to do so. Blair: ere are millions of dollars spent on laser drills, plating lines, plasma chambers, and multilayer board lamination presses, but the heart of the process is imaging the "printed circuit," and that is always low on the capital budget or is moved into the next fis- cal year. It's not just purchasing direct imag- ing printers, but all the support equipment needed to provide a micro debris-free sur- face on the resist-coated panel or core that's placed on the printer exposure tray. What was good for 3-mil lines and spaces is not for 2.5- mil and smaller lines and spaces. Krick: I also ask customers to be patient, even though we live in an impatient world. Mak- ing too many changes at once will only make things worse or more confusing when it comes to the traceability of failures. I know firsthand, as I lived in a shop for more than eight years before joining IEC. Finally, use your resources. For example, at IEC/Eternal we offer training and refresher courses to our customers on all the major imag- ing topics. We are happy to do audits, SEM work, and anything else to help our customers be successful with the products we offer. PCB007