[sdiy] PCB CAD woes

[Tom Wiltshire]

Well, I'm glad someone likes it!

Sounds like I probably need more practice…

Tom

On 2 Oct 2015, at 20:01, Tom Bugs <admin at bugbrand.co.uk> wrote:

> I disagree! Certainly for 'big' SMD (SOIC and 0805 typical) - neat as anything /// maybe partly practice.
> Despite being more metric at heart, I do all to 0.05" grid with a few 0.025" and an occasional smattering of 0.0125".
> Things line up lovely and neat in general! Compensation caps right across pins, resistor summers with tiny lengths to the summing nodes! And mainly just working on the 1 side with V+ and V- on the bottom - easy to plop decoupling caps in just the right place too.
> Much of this is practice though..
> 
> Ought to try smaller sometime, but I've got nicely set up now for this route and reckon it is an 'ain't broke, don't fix' scenario for now.
> 
> On 02/10/2015 18:23, Tom Wiltshire wrote:
>> Surface mount packages of all types are a nightmare, imho. Unlike through-hole parts, they don't fit on any overall grid. Through-hole parts you can fit on a 0.1" grid. Occasionally, shifting things by a 0.05" here or there helps tidy up.
>> 
>> SMDs are the exact opposite. Even if you want to line them up, you can't. The tracks go all over the place. Spacings aren't consistent. The devices come in a bewildering array of packages, none of which have any common multiples.
>> 
>> Electronics was always a mess, what with there being no real decision made whether we were in imperial or metric (6.35mm shaft or 6mm? 0.1" or 2.5mm? etc etc), but SMD made it a hundred times worse, since the little errors tend to matter much more at that scale.
>> 
>> I commiserate.
>> 
>> Tom
>> 
>> 
>> On 2 Oct 2015, at 18:02, 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 :-(
>>> 
>>> -Richie,
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> 
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