Virtual Questions

Here’s a question I received during my Virtual PCB chat session on March 8:

  • From Jack: “Here’s my default question (as a designer), what is your biggest headache from designers?”

My answer: “Probably the most common difficulty has to do with CAD library footprints. That’s really a headache caused by the CAD software”

  • Jack: “Ha, well it seems like the majority of problems stem from incorrect library footprints (including mask, silk, etc.). Maybe we just need to get together and make a universal library for everyone, eh?”

I’ve been hearing a lot of lamentations over the last year regarding CAD library footprints. It seems to be one of those issues that has been around long enough and is now reaching a critical mass of attention. There are a few partial solutions in the works. PCB123 is trying to make the most complete set of libraries possible. NXP has been supplying factory libraries to PCB123. There is the IPC-7351B land pattern generator. Some manufacturers give good footprint guidance at least (TI, Freescale). Sparkfun and Adafruit are supplying libraries for most of the components that they use and sell.

All good things and all in the right direction, but still not a consolidated universal effort. There’s also talk floating around of crowdsourcing libraries. I can see that working for Eagle and a few other packages, but I question whether large companies using expensive CAD systems would rely on such a thing. I guess that all means that we don’t have a solution in sight, but if the problem is getting broad-based visibility, than maybe someone will come up with an actual complete answer.

Duane Benson
Esperanto for CAD libraries

One thought on “Virtual Questions

  1. Excellent topic and one that I am involved in everyday. One of the bigger issues I see is the wide variety of requirements that different companies (end users) specify. For example, some companies want silkscreen, some don’t. Some want paste mask at 1:1 and want the assembly shops to determine mask opening and others want it built into the footprints. Everyone seems to want Pin 1 indicators and polarity markings shown differently. So the question is how do you come up with a universal library that satisfies everyone’s requirements? Or how do you get everyone to agree on a standard. The IPC sub-committees come up with guidelines but companies with thousands of legacy parts aren’t willing to change them – with good reason. I don’t know what the “complete” answer could be. Not in the near future anyway.

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