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62 DESIGN007 MAGAZINE I JULY 2021 Are dimensions still required on board outline drawings when you have a Gerber or other profile available and very intricate shapes and curves? Would a note be more appropriate with a tolerance? Stephen Chavez: Ah… this a debatable topic indeed, especially within our current technol- ogy and tools, which have improved greatly over time. As the integration between design teams and industry suppliers continues to evolve when we talk about the "digital thread" and the collaboration and integration during the hand-off stage from design to fabrication, quality content and quality data exchange are paramount. Within today's industry evolution, we now can generate intelligent data that far exceeds the use of simple non-intelligent Ger- ber data from our EDA tools. Today's intelligent data formats such as ODB++ and IPC-2581 provide the design team the ability to seamlessly integrate and exchange data content with our suppliers so that we can be more efficient and better opti- mized. Communications between the design team and the supplier are key. And designers must understand what is minimally required to be conveyed in order to produce the designed intent of the PCB/PCBA. Do we need to dimension everything? Can we simply add specific notes/instructions on our drawings? It's not a simple "yes or no" response. It depends on the complexity along with criticality of the feature of the design in question. If it's critical, then it should be docu- mented and conveyed to the supplier during the data exchange. is data exchange would include some form of documentation, especially regarding fabri- cation drawings that convey the engineering intent to the supplier. is is extremely impor- tant and attention to detail is critical. In general, one of the first lines in our fabrication drawings states the IPC class to which the board is to be fabricated, as well as what call-outs it is to be inspected to. is ties in the following industry specification that are recommend as industry guidelines and best practices: • IPC-352A Documentation Requirements for Printed Boards, Assemblies and Support Drawings • IPC-2614 Sectional Requirements for Board Fabrication Documentation • IPC-2615 Printed Board Dimensions and Tolerances • ASME Y14.5 Geometric Dimensioning and Tolerances With that said, every company has its own internal standards and guidelines. Typically, dimensioning a PCB within a fabrication draw- ing would show dimensions of critical features such as holes, slots, board outline/edges, and Q

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