Issue link: https://iconnect007.uberflip.com/i/1514189
48 DESIGN007 MAGAZINE I JANUARY 2024 Feature Interview by Andy Shaughnessy I-CONNECT007 At PCB Carolina, I met with Laura Martin, director of applications engineering for Sum- mit Interconnect. Laura has been at Summit for about a year, moving into the role from a similar position at Insulectro. She has now become Summit's go-to design for manufac- turing (DFM) expert, and she's working to move DFM further up in the design cycle, eliminating unpleasant surprises at CAM. Many DFM issues stem from designers not understanding all the steps in the manufactur- ing process. I asked Laura to share her thoughts on this situation, and she had several pointers for designers. As she notes here, many fab vari- ables can put your board on hold, so it's best to be prepared. Andy Shaughnessy: What are some of the most important things a designer should know about fab? Laura Martin: One of the most common DFM findings is the via or plated through-hole pad size is designed too small to meet the specified annular ring requirements. I don't think it's well understood how to calculate the correct pad size, and IPC documents don't include some of the manufacturing caveats. We did a webinar on this topic recently, and one of the things we cov- ered is how the type of final finish impacts the drill diameter. We compensate the drills differ- ently for HASL and ENIG finishes. We also con- sider the aspect ratio of the board, and the total thickness or thickness of each sub being drilled. Save Your Design by Understanding Fab Processes Laura Martin