Issue link: https://iconnect007.uberflip.com/i/1509257
44 DESIGN007 MAGAZINE I OCTOBER 2023 d e s i g n " P CB te c h spec check" using this newfound document. I first needed to find the category for the technology in order to check the guidelines. I quickly found QFN in the "Demand on Assembly" column and proceeded to look up the specs relevant to issues found by our manufacturing engineers. First, I could see that this chal- lenge had to do with a quad flat pack-style component including a large heat sink "slug" and otherwise referred to as a "bot- tom termination component" or quad flat no- lead (QFN). I went directly to the "Project Start Level" checklist to see how the responsible electronic designer could have easily referenced IPC-7093 to see more information on how to design this part footprint for better DFM. I won't address every DFM improvement here that I was able to suggest to our manu- facturing engineering team. But they were appreciative for the list of detailed IPC based improvement I was able to publish to be for- warded to our customer. I found this checklist knowledge very empower ing. As a designer of QFN foot- prints, I must admit I didn't know that IPC- 7093 exists. But with this checklist as a guide, I am led to the IPC-based knowledge I need for help. I can read the spec and research what other well-known contributors have written on similar design challenges when dealing with these parts. I was amazed when I searched this standard and found a very helpful presentation on QFN prinicples by Vern Solberg, which will prove very effective in "selling" these IPC spec-based DFM ideas to our customer. IPC Checklist for Producing Printed Board Assemblies • Checklist at the Project Start Level • Checklist at the CAD Level (map) • Checklist at the Printed Board Ordering Level (map) • Checklist at the Assembly Ordering Level (map) • Checklist at the Cleaning and Conformal Coating Level (map) • Checklist at the Quality Check Level (map) Conclusion e void of knowledge about how to collaboratively design within the electronics industry continues across the PCB design organiza- tions I've participated in. It seems as though 12 different designers will always give you 12 different ways to approach a design challenge. at's not necessarily a bad thing. However, when choosing to adhere or reject to any of the 12 ways, I always want to hear first about how doing so will help the project meet an indus- try specification. I always say that a good PCB designer needs to see a dozen different ways of solving a design problem. However, great designers—those whose eyes are set on vol- ume production—will draw only from ways allowing them to create and specify design solutions conforming to an inspectable IPC standard or collaborate with others to create one if it doesn't to exist. When I think about the need to learn more about PCB industry standards—where to find them, how to access them, and how helpful the layout of this checklist has been for me— another one of Mr. Fenoglio's woodshop say- ings comes to mind. is one is about storing valuable tools: "A place for everything, every- thing in its place." DESIGN007 Kelly Dack, CIT, CID+, provides DFx centered PCB design and manufacturing liaison expertise for a dynamic EMS provider in the Pacific Northwest while also serving as an IPC design certifi- cation instructor (CID) for EPTAC. To read past columns, click here. Example of a problematic footprint.