kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Tue, Jul 31, 2012 at 08:05:07AM +0200, Miguel Angel Ajo Pelayo wrote:
> 1) Silkscreen vs Soldermask

What do you see which isn't poking you in an eye xoring the two gerbers?

> 2) Silkscreen alignment can be seen much more clearly

Please tell me what you mean with silkscreen alignment, I simply don't get it... also at the end silk is mostly eaten away by registration clearances (in practice everything smaller than 0805 is silkless). When you have components packed on a 0.5mm grid there isn't a lot of place for silk! Also assembly is 95% automated, most of the board we make has no silk at all.

> 3) You can add your mechanical case and check if all the connectors match
> their holes and if all the holes in the PCB match the screw supports
> correctly.

You have a point with that, but then you'll need *accurate* connector models which are a) supplied only by some manufacturers (especially Molex and TE) and b) in STEP or IGES

Actual workflow varies depending on if you design the enclosure on the pcb or you have to fit the pcb in an enclosure (luckily for me it's mostly the former)

For now pcb holes can be matched with the dxf plots.

> The ideal would be plain step exporting from a pcb file, but we will have
> that sooner or later :-)

Some volunteer can try to wrangle opencascade which, AFAIK, is the only open
source stuff handling STEP around.

>     I think I've never made a 3D model for a component, but I use them a
> lot.

I stopped when I noticed that I was using more 'strange' components than available ones... think about it, you actually don't need for the above reason all the chip parts and most of the jedec cases... you need a) connectors and b) big/strange stuff (like vertical modules, relays and transformers). Sadly most of these are not standardized... heck, even a plain DE9 connector can have about 6 different profiles!

>     In other packages I import all the STEP files that the component part
> manufacturers provide. It really helps to check your silkscreen overlay,
> and to check you footprint holes :-), It also helps to check if your
> connectors are colliding to any surrounding element.

You are lucky to find all the STEPs then. On the last board I've done only about 30% of the connectors had STEPs around (yes, it has a *lot* of different connectors:D). In fact for one of them we need to delay the enclosure waiting for prototypes since even the drawing on the datasheet is clear... we don't actually know how the fscking thing protrudes from the board!

>    Once you start, you get somehow "addicted" to its benefits.

Maybe with a full 3D workflow (ECAD included) it could work *if* there were all the resources available. And especially a static render is only eye candy for me:D

-- 
Lorenzo Marcantonio
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