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Note that I use the term “design for profitability,” or DFP, as opposed to any of the other acronyms such as DFM (design for manufacturability), DFT (design for test), or DFA (design for assembly). I’m taking this approach because it really all comes down to profit, doesn’t it?
Designers have the power to design profit into the board, or, conversely, inadvertently increase costs and remove profit from the PCB. In this article I am going to go over just a few of the challenges that fabricators routinely face and some typical solutions, especially solutions that can affect your bottom line.
I will start with DFM. Generally, this is the first stage for prototyping and DFM depends greatly on the capabilities of your chosen fab shop. Some designs are finished with autorouters after the critical traces have been hand-placed. It is at this point that unintended issues can arise between design and fab.
An example of this is same net-spacing violations where a track may “double back” near a surface mounted component, creating same-net spacing violations (Figure 1). Whereas the software does not see these as legit violations because they are same net, a fabricator knows that any features creating spaces below 0.003” can easily flake off at the image stage and create havoc elsewhere in the form of shorts. Edit time must be taken at the fab stage when these same-net spacing violations occur and the slivers eliminated. Some CAM software packages have a sliver fill option, but again this requires additional edit time at CAM.
Read the full article here.
Editor's Note: This article originally appeared in the March 2013 issue of The PCB Design Magazine.
Tamara Jovanovic, Happiest Baby
When I was a sophomore in college, I had an amazing professor for Physics II: Electricity and Magnetism. He made a series of complex topics fun to learn, and his personality and way of teaching were almost tailor-made for the way I like to learn. He explained new concepts through practical examples, and always kept students engaged throughout the class, making sure everyone understood the lectures. Physics II was an engineering prerequisite, and I didn’t mind taking the class since I really enjoyed the material. However, I did find myself wondering a few times, “Will I ever use any physics in real life?” It turns out that the answer to the question was yes.
Andy Shaughnessy, PCB Design007
As signal speeds continue to increase and feature sizes decrease, PCB designers are beginning to pay greater attention to test and design for test (DFT) strategies. Bert Horner, president of The Test Connection in Hunt Valley, Maryland, is spearheading this drive to show designers the benefits of a solid DFT plan, as well as the downside of not having a test strategy. I met with Bert at PCB Carolina, where he was exhibiting and presenting a paper during the conference. We discussed his presentation, as well as why designers need to understand test and DFT issues, and why we need to see the PCB as one small—but very important—part of the entire system.
Andy Shaughnessy, Design007 Magazine
During PCB West, I caught up with DownStream Technologies co-founder Joe Clark and Senior Product Marketing Manager Mark Gallant. We discussed some of their latest tool updates, including a greater focus on bringing post-processing functionality, such as inter-layer analysis capability, to rigid-flex circuits. Joe also offered a look at global design trends going into 2023, as more engineers take on PCB designer roles while senior designers are retiring.