Printed Circuit Design & Fab - April 2008 - (Page 32) IMAGING LASER DIRECT IMAGING Made Easy With over 400 installations worldwide, LDI is gaining global market acceptance. by GUY ALON and DR. RALPH BIRNBAUM Laser direct imaging (LDI) technology for PCB applications is over 30 years old, yet, it is less than a decade since the technology became a production proven tool. Today, there are over 400 units installed worldwide. The reasons why it took so long to develop this installed user base are many and varied, including technical hurdles such as laser technology itself, computing power, availability of dry film / liquid resists, optics, the art of combining these technologies, as well as cost and the ability to support customers. During that time, many articles were written and presentations made on all the wonderful benefits LDI brings to the PCB manufacturing process, such as no photo-tool printing, faster turnaround for small jobs, tighter accuracy, dynamic scaling functions, and high depth-of-focus. There is another side of the LDI that is often overlooked; that is, the simplicity of the LDI solution. To penetrate the imaging market, the suppliers of LDI equipment have developed a series of features that enable both performance to specifications, and ease of use. Using the feedback from numerous LDI customers, the systems have been improved. The features of LDI equipment today make it an easier option for a PCB manufacturer to implement, and because the process is digital, it is easier to use than conventional imaging ever will be. Once the LDI users realized the advantages and potential for the technology, they challenged LDI suppliers with requests and ideas that, in essence, established the basis for process improvements. What makes an LDI system easy to use? There are 4 groups of features that highlight the LDI’s general ease-ofuse. They are: ■ Process compatibility. LDI fits into your current process with minimal or no changes ■ User interface. LDI allows you to be up and running in minimal time ■ Image registration. LDI is compatible with many different target types ■ Process Feedback. LDI provides instant feedback on registration and other useful statistical data Process Compatibility UV-based LDI systems will work with the same conventional resists as do conventional exposure systems. The entire process has become simplified through the removal of the photo-tool. Other than that, no change is required. There are FIGURE 1. Optimization software computes groupings for scaled phototools. 32 PRINTED CIRCUIT DESIGN & FAB APRIL 2008
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