[sdiy] Eagle footprints

[Neil Johnson]

Hi Tom,

> I've been caught like this too - but how stupid is this situation?!
>
> Software houses and parts vendors spend time and money getting together the most extensive parts libraries they can, but nobody uses them because they probably have some errors. Instead we redo all the work they already did...so we can get it wrong ourselves?
>
> It's daft, but we all do it. ( Why? Wrong list for psychology questions, I know…)

The big boys in the CAD market -- Mentor, Cadence, Zuken, etc -- don't
put much effort into libraries for several reasons:
- big customers don't buy the product based on the size of libraries,
they want other things (integration with manufacturing systems, tools
that speed up board layout, signal integrity analysis, thermal
analysis, etc), so why spend money on something that won't get you a
sale?
- libraries need maintaining, when vendors update footprints, new
parts come out, old parts are EOLed, etc.
- big customers have CAD data management teams that work with their
own QA departments and work to industry-specific standards --
automotive, aerospace, medical, nuclear, defence, consumer, prosumer,
high-quality, high-volume, etc.  One library won't suit everyone, and
the big customers will ignore them anyway.

Further down the CAD tool foodchain the budgets for creating libraries
get smaller.  You get what you pay for.

Finally, you get to the bottom of the stack: free(mium) tools like
Eagle, DesignSpark, Altium's CircuitMaker.
Below that the FOSS tools like KiCad, GEDA, etc.

And then there are companies who specialise in producing parts
libraries and/or tools.  For example I occassionally use Ultra
Librarian, which has a free reader/converter and so I can take BXL
files from TI, Maxim, etc and autogenerate symbols and footprints for
a wide range of parts direct from vendor data into the format needed
for the CAD tools I use.  For example:
http://www.accelerated-designs.com/ultra-librarian/
https://www.maximintegrated.com/en/design/packaging/cad/
http://webench.ti.com/cad/
Other manufacturers that provide BXL files include Analog Devices,
Microchip, Freescale, and so on.

Having been sorely bitten by bugs in high-end CAD vendor libraries I
no longer trust them for anything other than to provide some examples
for training.

Neil
--
http://www.njohnson.co.uk