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Re: Kicad libraries for pcbnew


--- In kicad-devel@xxxxxxxxxxxxxxx, Vesa Solonen <vsolonen@...> wrote:
> On Fri, 12 Mar 2010, viking632 wrote:
> > I've added the DB-9,15,25,37 and the
> > DSUB15 ("VGA") connectors, and the TO220-11.
> Very nice! Your module work is just outstanding amd all my new designs are 
> going to use them as much as possible.


> > Now, the pin #s floats above each pin (male) or inside
> > the hole (female), which is a lot easier to do :-)
> Excellent.
> > Also, I've renamed the resistors, so
> > the name only reflects the pin spacing.
> > I didn't like the naming, and someone also pointed out that the
> > wattage doesn't uniquely determine the resistor package size.
> That someone was me and my special thanks goes to your work on capacitors.

Finding old posts is a nightmare, and the search function doesn't work, so :-(

I'll add the missing capacitors when I get 'round to it: Ceramic, tantalum,more axials.

I've renamed the resistors yet again, now they're called R-{IM}<pitch>, with an optional 'V' on the end (Vertical mount).
This groups all the resistors nicely together in cvpcb :-)

> > There are a number of issues that I would like som opinions on:
> > 
> > * The pins on TO126 and TO220-5 are spaced quite close together.
> > I think the solution for TO126 is to reduce the pads slightly,
> > and I could do the same with the TO220-5, or I could zigzag the
> > TO220-5 pads, like on the TO220-5R (but by only one pin-pitch) ?
> I think we should supply both variants as commercial PTH boards can use 
> very small pads and it is even advantageous (less solder), but for hobby 
> and hombrew use even non standard pin forming may be ysed advantageously. 
> Exact pad size and clearances come from design rules anyway, so library 
> may be designed as a good defaults in mind.

I've reduced the TO126 and TO220-5 pads slightly,
and will add the zigzag variant of the TO220-5 later.

> > * The current libraries provides several versions of the
> > TO92 and TO18 with varying pin mappings, something that
> > IMHO should be taken care of in eeschema or cvpcb,
> > by providing a mapping from pin function to pin number.
> > The TO3 in the current libs also maps the pins wrong:
> > The house is numbered #1, and pin #1 is numbered #3.
> > Are anyone looking into such a function-to-pin mapping, or
> > should I provide (horrors) the -CBE, -EBC, -DGS, etc. variants ?
> That pin mapping functionality is not yet there, but if those with greater 
> coding skills agree with my proposal it will be some day. Along with pin 
> swapping, etc. That's my long term goal anyway. Footprint library should 
> just stick to the standard numbering and nothing else. Otherwise the 
> system is a mess after a while. Anyway it's few clicks of work to change 
> schematic symbols pin numbering, so that should be the way.

Off hand, I can only think of transistors that needs pin mapping,
but yes, it would be very nice to have (any volunteers ?-)

> > * General guidelines on pin size to drill hole and Pad sizes ?
> > I found a site that suggested Pad size == 2*pin size
> > (or smaller if the spacing doesn't permit that).
> > What about drill holes ? Is pin+0.1mm OK, or pin+0.2mm ?
> > 
> > Ã?yvind.
> I can not give a definitive answer to that, but some sane defaults might 
> be 2 times pin size and pin+0.1mm. Even better might be just to specify 
> the pin diameter with tolerances and specity that. The exact diameter 
> depends on hole plating too and it would be quite easy to fix the whole 
> PCB hole sizes after the layout with a manufacturing helper script.
> For my home made PCBs 0.8mm is a general hole with 66 or 70 mil pad so it 
> turns out to be about 2.1 times the hole size. It's adjusted case by case.

I'll aim for pad = 2*hole, hole = pin+0.1 ...

> BTW, if you have time to add horizontal and reverse horisontal (thermal 
> pad upwards) plastic flat TO-packages (TO126, TO220...) to your library 
> I'd be very delighted. They allow all kinds of very usable layouts with 
> heat sinking.

Done :-)

I've added three variants: Heatsink up, heatsink
down w/o pad and heatsink down with (SMD) pad.
In all three cases, there's also a mounting hole on the PCB.
I've added all three variants for all the TO-PPs (Plastic
Packages), even the fully isolated ones, but I'm thinking
that maybe we could skip the padded variant for those ?

I haven't added horiz versions of the TO220-5R (PentawattV)
and TO220-11R, as these have already had their pins bent.
I can add them if you like ?

I've also added a horiz version of the SIP3 and 4, but I'm not
sure if they're useful. Let me know if I should keep them ...

> Best regards,
> -Vesa

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