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Diodes in standard library - square pin??
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shelmichaels
Hi...
I'm trying to get up to speed with KiCad, and it's going pretty well. 8^) One thing that bothers me, though, is the footprint/module for diodes as presented in the standard library. In the library version that I got when installing KiCad just a few weeks ago, the anode is marked as pin 1, and the cathode as pin 2. Good. But, the square pin shape is on pin 2. Not good?? Doesn't this violate conventions on pin shapes? Isn't it always pin 1 that is supposed to get the square shape? Would I be painting myself into some kind of corner if I change all diode modules to have square shapes for pin 1? Thanks for your time in looking at this. Best regards, ...Shel |
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Andy Eskelson
It's only a convention, you don't have to follow it. It's one that I
never use if I am designing my own modules I just use the same shape throughout. When I was laying out PCB's with pad and tape you had a choice of round or if you were very posh oval, and that was it :-)) When CAD type PCB came into the industry, it was fairly common to use a different shaped pad to identify the the same pin that was identified on an IC, usually pin 1 Square pads can be a problem because the corners can prevent other tracks routing near them, so I have seen octagonal p[ads in some cases. The practise crept into other components in some cases. However there are SO many different components that it does not work for everything. Some big stud rectifiers had opposite connections where the stud could be the anode of cathode depending on the device. Some people use a square pad to identify the positive end of a cap, but if you lok and a lot of caps, the case identifies the negative pin. Over the past couple of decades SMT has taken over most of the commercial electronic world and so the pad shape is a moot point, it has to be a rectangular shape everywhere. Another point, you will also find some components that are identified as A, K -- e,b,c -- d,s,g1,g2 and so on - I've see them all. For hobby use you just get on with it and use whatever convention suits you, for commercial use the silkscreen is the place for identifiers generally. Also don't forget that many commercial units are built with pick and place technology, and the robots don't care about pad shapes :-)) Andy On Sun, 15 Jul 2012 03:49:52 -0000 "shelmichaels" <yahooshel@...> wrote: Hi... |
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Hi,
I always check pin1 and pin2, or pinA and pinB wth all components, and I change module or component numbering to fit what I need. This way I have made my own library. See that diode footprints are very different: through hole or smd, larger or smaller, with two or three pins... Don't worry about changing your footprints numbers since they are only a matching convention between eeschema component and pcbnew module. Regards, Pedro. Hi...8^) presented in the standard library. In the library version that I got when installing KiCad just a few weeks ago, the anode is marked as pin 1, and the cathode as pin 2. Good. But, the square pin shape is on pin 2. Not good?? that is supposed to get the square shape? Would I be painting myself into some kind of corner if I change all diode modules to have square shapes for pin 1?
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Peter Bennett
I don't care about the pad shape, but I do want a bar across the component body outline at the cathode end - matching the marking on the real component (although I do see that the diode footprint I used does have a square pad for the cathode).
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I used to use Protel at work, and I recall problems with the schematic diode pins "numbered" A and K, while the footprint pins were 1 and 2, until I changed them to A and K. (Protel apparently didn't allow the schematic library designers to talk to the PCB library designers - they also had things like DIP-14 in the schematic library, and 14DIP in PCB...) On 7/14/2012 8:49 PM, shelmichaels wrote:
Hi... --
Peter Bennett, VE7CEI Vancouver, B.C., Canada GPS and NMEA info: Vancouver Power Squadron: |
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Yes Protel sometimes was Prohell because of it (weird library stuff). (LOL)
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PCAD isn't too much better but Protel did have some nice editing features in the schematic which KiCAD lacks. One of which was too use the enter key like a right mouse button click when you used the keyboard for positioning components as well as editing the library side of things. The windowed zoom was handy as well. That was for eeschema haven't spent much time with the PCB side of things in KiCAD as yet. Stephen ----- Original Message -----
From: Peter Bennett <peterbb@...> To: kicad-users@... Cc: shelmichaels <yahooshel@...> Sent: Sunday, July 15, 2012 10:14 PM Subject: Re: [kicad-users] Diodes in standard library - square pin?? I don't care about the pad shape, but I do want a bar across the component body outline at the cathode end - matching the marking on the real component (although I do see that the diode footprint I used does have a square pad for the cathode). I used to use Protel at work, and I recall problems with the schematic diode pins "numbered" A and K, while the footprint pins were 1 and 2, until I changed them to A and K.? (Protel apparently didn't allow the schematic library designers to talk to the PCB library designers - they also had things like DIP-14 in the schematic library, and 14DIP in PCB...) On 7/14/2012 8:49 PM, shelmichaels wrote: Hi... -- Peter Bennett, VE7CEI? ? Vancouver, B.C., Canada GPS and NMEA info: Vancouver Power Squadron: ------------------------------------ Please read the Kicad FAQ in the group files section before posting your question. Please post your bug reports here. They will be picked up by the creator of Kicad. Please visit for details of how to contribute your symbols/modules to the kicad library. For building Kicad from source and other development questions visit the kicad-devel group at ! Groups Links |
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Regarding pad shapes, I came to like the approach that W. Pulliam from AMD presents in "Quick and Easy Land Pattern Creation" ().
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Best regards, Esteban --- In kicad-users@..., "shelmichaels" <yahooshel@...> wrote:
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shelmichaels
Thank you Esteban, that is a really interesting and useful document!
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Best regards, ...Shel --- In kicad-users@..., "e_e_lucchesi" <e_e_lucchesi@...> wrote:
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All:
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The "Quick and Easy ..." document was useful and interesting. The IPC7351 standard is also pretty interesting. Somebody has a copy of the A revision at: (I'm not too sure how "legal" that copy of the spec. is.) The IPC7351 standard goes into more detail about PCB land design. Regards, -Wayne --- In kicad-users@..., "e_e_lucchesi" <e_e_lucchesi@...> wrote:
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--- In kicad-users@..., "shelmichaels" <yahooshel@...> wrote:
My advice, which applies to any EDA, is to largely ignore the libraries that come with it. When there is a part in the library that is worthwhile, export it to a new library and modify it to suit your preference. It won't take long before you have a nice set of libraries containing many parts that you actually use, without having to sift through thousands of random bits. Another advantage is that if you reinstall or upgrade KiCAD, it won't overwrite your changes as it will if you modify parts in the default library. As for pad shapes, do it the way you prefer, it makes no real difference in the end as long as you are consistent. I generally use A and K rather than 1 and 2 because there are many diodes in various SMT packages that use other pin numbers. |
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