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Page 48 of 109

SEPTEMBER 2021 I PCB007 MAGAZINE 49 steer customers toward formats that are easy and reliable for the design team, as well as effi- cient for the fabrication CAM teams. And despite all the developments in ODB++ and IPC-2581, Gerber continues to be the pri- mary choice for most PCB designers. Gerber shows no signs of coasting into a well-earned retirement. PCB007 What Does It All Mean? What we conclude from these responses is that designers find the process of preparing all the files for transfer to be onerous, difficult, and error prone. e easier the fabricator can make the transfer of not only the files but the design intent, the better in the eyes of the OEM cus- tomer. is is to the extent that fabricators can By Dr. Luca Gautero SÜSS MICROTEC The age of internet shopping re- leased us from the hassle of mov- ing ourselves from shop to shop to obtain the best deal on the most suitable product, which has result- ed in an improvement to our quality of life. Still, such alleviation comes at a cost: dealing with almost per- fect qualitative comparisons. Such comparison can be objective and final; thus, it should be easy to get it right the first time. Still, we are left to judge what is good enough and what is better than good enough. If inkjet tools could be found on an e-commerce site, fitting nicely into the catego- ry of "industrial and scientific, and a subsection of "additive manufacturing products," aside from di- mensions and weight, there would be several prod- uct specifications of which many would specify the jetting properties; these would basically detail the printhead(s) in the system. The knowledge needed for the right selection is how these specifications re- late to the application at hand (for example, solder mask). In my opinion, these are the most important prop- erties of a printhead (PH): • Native resolution, also known as nozzle per inch (NPI) • Max frequency and driving voltage • Minimum drop volume (assuming multidrop capabilities) • Design for arraying, amount of nozzles and positioning compensation mechanism • Heating and ink recirculation In the following, each of these properties will be addressed and discussed. They will include a short note on the dot per inch (DPI) unit, which is the common printing res- olution unit. An image as a 2D ob- ject needs two resolutions. Both di- mensions often share the same res- olution, therefore only one is pres- ent. Inkjet printing identifies and implements the two resolutions (even when equal in value) in a dif- ferent way: the cross-scan resolution is a combina- tion of NPI and small steps movements. Its orthogo- nal equivalent, the in-scan resolution, imposes the relation between speed and jetting frequency. A solder mask print benefits from printing resolu- tion in the tens of microns. A resolution of 2550 DPI delivers pixels just below 10µm size. A printhead with a NPI of 50 would need 50 small steps (steps of 10µm) to achieve such cross-scan resolution. At every small step, the printhead coats part of the pat- tern over the full length of the substrate. Despite any high printing speed, the compensation of a low NPI comes at the cost of precious time. To continue reading this column, click here. Additive Reality: Printhead Selection or 'Shop 'Til You Drop' Dr. Luca Gautero

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