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30 DESIGN007 MAGAZINE I JANUARY 2023 are recommended—and that's all just for the scissors. We could continue with a discussion on the whole line of rotary cutters, but let's escape from the sewing tool aisle while we're still young. My wife expertly navigated her way through the various areas of the store, choosing between different fabrics, trims, and zippers. Next, she explored several different types and colors of thread, plus the bobbins required to install this thread in her own sewing machine. But- tons and interfacing had to be selected based on color, size, and durability. Just for kicks, we looked at patterns for potential future projects. However, all this took far less time than I would have expected because she had already planned how much fabric she would need, as well as how all the seams, hems, and stitching would be coordinated. en she said something about a phone, and I thought that we were headed to the Verizon store next. Nope, she meant "foam," not phone, which was another unique yet crucial component of this project. Would you like me to tell you how many different types, styles, and sizes of foam there are to work with? I didn't think so. By the end of the day, I had come to realize that my extremely naïve and rather arrogant perspective on my wife's sewing was com- pletely out of line. She obviously has just as much—and probably a whole lot more—expe- rience and expertise in the world of sewing as I do in PCB design. Aer following her around the cra store, I know that I would much rather Would you like me to tell you how many different types, styles, and sizes of foam there are to work with? I didn't think so. spend the day puzzling together some com- plex DDR routing than trying to understand how to sew. But isn't that the case with most things? ere will always be those who have a greater amount of experience and exper- tise in a specific subject matter. To quote an adage: "ere's always a bigger fish." An excel- lent example of this is the advanced packaging of PCB components, and how part selection affects the way we lay out a design. When I first started designing circuit boards, components were less dense and more generic in both size and shape. I remember being told to leave enough room at the top of my through- hole 14-pin DIPs for a bypass cap. When I asked for the size, shape, or part number, I was told that it wasn't important; I just needed to cre- ate a generic part with a 0.4" x 0.1" rectangle using 62-mil pads spaced 300 mils apart from each other. ey (whomever "they" were) would figure out later what to put in there, or they would just leave that part location empty. I wouldn't recommend using a relaxed com- ponent selection technique like that on a next generation smartphone design, as it probably won't get you many admirers. Today, there are many component packaging variables that designers must consider when designing a board. Here are a few that come to mind: • Functionality • Power • Price • Availability • Component life cycle • Routability • Human interface Depending on the options, designers need to choose the part that will work best for their circuit, but they also must take into account the part's power needs and thermal issues, as well as whether the board design will sup- port it. Before they can check off component selection on their to-do list, they also need to consider the part's price and availability, and

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