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40 DESIGN007 MAGAZINE I AUGUST 2023 that needs to be drilled and removed from a board. In addition, a clever design can optimize spacing between the holes, which reduces the amount of motion a drill needs between drill- ing. Both design optimizations might seem minimal, but their savings can add up for large manufacturing runs. Better Drilling for Better PCBs Drilling plays an integral role in the PCB manufacturing process, and PCB designers need to understand how their designs affect drilling efficiency and accuracy. Optimized through-hole and pad sizes can facilitate the drilling process and ensure high-quality PCB manufacturing. By working closely with the PCB manufac- turer and following best practices, designers can achieve better efficiency and reduce board waste. Accurate drilling is key to a reliable and efficient board, and by focusing on these essen- tial elements, designers can produce PCBs with fewer errors and failure rates that end up being cost-effective. DESIGN007 Tim Totten has been at Sunstone since 2004, where he has played an integral role in initiatives to enhance the drill department, including training his colleagues on new equipment, developing processes for new product lines, and learning how to write G-code. Download The Printed Circuit Designer's Guide to… Designing for Reality by Matt Stevenson. You can view other titles in the I-007e library here. Chapter 1: How We Got Where We Are The Paradox of DFM Before the development of PCB computer-aided manufacturing (CAM), the process of preparing a board for fabrication and assembly was as cumber- some as actually designing the board itself. Early PCB manufacturing involved several manual pro- cesses which remain largely intact today, mirrored by a modern digital equivalent. Manual design for manufacturing (DFM) began with PCB artwork that was produced by applying an opaque film on a clear piece of mylar. The examination and measurement process involved using an eye loupe, and any necessary edits were made by either carefully scratch- ing off the tape with an X-ACTO® knife to provide additional clearance or fill- ing in voids with a black marker. Tasks such as drilling and compo- nent placement relied on custom- built mechanical programs. These were stand-alone solutions, created individually in a time-consuming and painstaking process involving specialized equipment such as drill bomb-sight machines. With such an intensive and manual process, there were many challenges to overcome to meet all the necessary operational complexities needed to produce a circuit board. As the complexity of systems increased, these physical sheets were replaced by digital files, but the manual complexities persisted. During the 1980s, the design data transferred to manufacturing facilities was heavily split as a result of the myriad of solu- tions necessary to produce a PCB. Gerber data was used for artwork, Excellon drill format for mechanical drilling, typically a centroid file which assisted in component placement and, if you were very lucky, a netlist file in IPC-356-A format was included. This data came accompanied by a corresponding component bill of materials. Continue reading. BOOK EXCERPT The Printed Circuit Designer's Guide to... Manufacturing Driven Design