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20 PCB007 MAGAZINE I OCTOBER 2022 e advantages of digital cir- cuitization techniques have been described in detail by suppliers of equipment and photoresist. Since phototool generation and conditioning are omitted, there is the advan- tage of shorter lead time. Small lots can be customized at no extra cost, as an example, with added date and lot number information. ere may be an advantage in fine line imaging of surfaces with poor co-pla- narity because of the depth of focus of the laser beam. Maybe the biggest advantage is the ability to scale, i.e., to change the dimension of each individ- ual exposure for best fit to ref- erence points on an underlying pattern of a multilayer struc- ture. However, early digital imaging systems had substantial drawbacks, such as Orbotech's DP100 which used an argon ion laser with lim- ited radiation power, high power usage, and high cooling requirements. For years, LDI was synonymous with digi- tal imaging. While most early commercially successful digital processes involved the use of lasers, other more recent processes use non- laser light sources such as LEDs (light emit- ting diodes) that consume less power, last lon- ger, and have a higher light intensity output (Figure 1). Alternatively, various types of mercury lamps are making use of more than one wavelength. Others use inkjet technology to build image patterns such as legend print, solder mask, or etch resist. ey all have in common the building of a pattern, pixel by pixel, and they employ digital "on/off switches" to form the pattern. e switch might be an optical modu- lator (as in laser direct imaging) or an array of liquid crystal polymer cells (LCPs) that can be rendered translucent or opaque by addressing it with an electrical pulse. e switch might be micro-mirrors on a chip, such as Texas Instru- ments' Digital Micromirror Device™ (DMD), whereby tiny mirrors are addressed with an electric pulse so that the mirror is either tilted to direct the light toward the substrate or away from it (Figure 2). e following is an overview of develop- ment and commercial digital imaging systems recently introduced. Altix-Automata-Tech, the French supplier of imaging systems, first introduced its ADIX- System at productronica 2013. It is based on an advanced high-power LED radiation source (ALDS), a dual multi-wavelength UV-LED, and DMDs. e system is suitable for rigid and flex substrates and has automatic handling options. Earlier systems using DMDs include: • ORC's DI-Impact (formerly by Pentax) • Hitachi's DE imagers DE-H, DE-S, and DE-F series • MIVA Technologies GmbH, Germany, Miva 2600X Direct Imager Figure 1: Next generation digital direct imaging (DDI) uses various light sources and the ubiquitous TI DMD micro-electrical-mechanical system (MEMS) micromirror to direct the rich UV light 3 .