[sdiy] PCB CAD woes

[rsdio at audiobanshee.com]

On Oct 2, 2015, at 10:02 AM, "Richie Burnett" <rburnett at richieburnett.co.uk> wrote:
> Surface mount SSOP packages with either 0.65mm (0.0256 inch) or 0.635mm (0.025 inch) pitch.  Who's bright idea was that!?!?
> 
> Have just laid out a board full of different SSOP packages and now have to redo half of the footprints because they're "slightly" out :-(

I've never seen the 25 mil (0.635mm) packages, just the 0.65 mm (25.6 mil). What's an example?

I always double-check the CAD designs against the data sheet, and I always download the data sheet directly from the manufacturer - not any of the "convenient" web storehouses of random data sheets.

Are you using Eagle? It's a great environment, because there are so many packages and symbols already done, and more to download. However, there are also many mistakes (I've had PCBs with transistor pins in the wrong order, due to a bad package), and the designs may not be compatible with your assembly shop. So, I recommend making your own library, reviewing all packages for accuracy, and then copy designs to your own library if they need to be changed. Over time, you'll have a collection of packages that you've vetted personally.

Brian