Design007 Magazine

Design007-Oct2023

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OCTOBER 2023 I DESIGN007 MAGAZINE 43 and manufacturing specifications, but who is responsible during the various stages of engi- neering, manufacturing, and test. Aer pre- viewing this checklist, let me tell you a story about how I put it to use right away. Our assembly line was having a challenge assembling a QFN part in which the PCB designer must have "dreamed up" a land pat- tern to attach the part to the PCB using a complicated window array, presumably to reduce the solder deposition. e footprint was "designed" but to what standard and with what manufacturing parameters in mind? e land pattern incorporated several "creative" technologies, including via-in-pad, solder-on- pad, and special "windows paning" features to attach the part. DFM r u l e s a p p e a r e d t o be ignored for every technology addressed o n t h i s f o o t p r i n t . O u r ma n u f a c tu r i ng e n g i n e e r i n g t e a m exclaimed, "What the heck?" My response was to perform a PCB notes oen reference specifications intended for design, not manufacturing. e numbers and class designations are oen inappropri- ately assigned or non-existent. I oen make the point that every other stakeholder in the PCB industry adheres to a process and checks their output to a spec. Why should the process of PCB design be any different? PCB design must be considered a process by the PCB designer and must therefore be checked to some appropriate specifications, but which ones? Based on the wide variety of designs I review from our customers across North America, designers could use some help in this area. I've recently come across a useful key to help solve this issue. IPC has published a PCB checklist guideline titled IPC Checklist for Producing Printed Board Assemblies. is doc- ument not only serves as an effective roadmap pointing designers to existing PCB design

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