Hello group, hello Phil.
> I'm toying with the idea of building a completely new set of > libraries for Kicad (and possibly EAGLE as well). Yes. this is the reason i startet making the library i loaded up the last days, and therefor i got strangled by the symbol editor (because i created symbols with a space at the name), and so i wrote the symbol editor manual i loaded up the last days....:-) I started creating this symbol library at the spring of this year, and it is now revision B.....next step would be making smaller and bigger symbols. sometimes i find it convenience to get as much as possible to one sheet at the schematic.....and at other situations i would prefere only few big symbols on a schematic.....which can read sometimes without glasses. ;-) I think there will be some more revisions in the next years.... But before finishing this, i will Start creating some often used footprints. With extra large holes and annulars i would prefere for thru hole, and extra large SMD Pads, i like to hand soldering. ;-) This all stems from > the fact that no CAD package I've used thus far has had what I'd call a > "decent" set of libraries, and IMHO it's gotten to the point where > something really needs to be done... > There will be a need for a good sorted basic library, but for special devices, it will be better to create your own. The question ist do determinate the border between common and special devices. For symbols, it would be nice to have a library with most common electronical devices like resistors, capacitors, chokes, transistors, diodes ec. so you can use them as a painters palette to groupe this devices around your ics or create entire circuits from them. Then you need a symbol library for the most common ICs, especial classical digital ICs, Op-Ambs, Comparators, Optocouplers and the most common microcontrollers and some well known special purpose ICs like 555 or 556 or some switching regulators and sutch stuff. On the other side i would be nice to get the most common footprints. There are some requirements from JEDEC(?), but every footprint in some way is a compromise, and you will come quick to a situation, where you would like to balance the compromise to one or to another side. As an example, footprints for oven soldering for simple smd parts like 1206 or 0805 ec. are well known and proven, but what, if you want to make a design for easier hand soldering? there you often would use bigger pads. Thru hole parts are another thing. You would use an classical 1/2W (1/3W) Resistor in a 10mm Raster. But in some designs you would like to save space and put this resistor into holes for 7,5mm raster or you have to cool the devices by longer wires and mount it to a 15mm raster system. Than you have some tousand very good capacitors with low temperature drift, but with very odd conection wires of 1.2mm..... So with footprints in smd and throu hole in the standart you will get a good compromise, but this will be a huge work to be done. First you will need footprints for devices with 1 terminal (solder pads for a wire or pads for a measurement place). This will be easy. One lonely pad in different sitzes and with different drills (from 0,8mm to 5 or 6mm btw. there imperial counterparts) for throu hole. Next the footprints for devices with two terminals.....different distance, different shapes, and also different holes for thru holes (even for the same distance) Notice, that there is a difference in silkscreen.....axial, radial some axial have the device between leads, but other are complete mouldet.....diodes can be unidirectional or also bidirectional. ec. > As I see it there are a few problems in common with most CAD libraries: > - Bad design. Pads with impossible annular ring sizes, stupid drill > sizes, SMD pads that are barely larger than the pad on the component > itself (and thus utterly impossible, or at least very difficult to > hand-solder). No.Most People use somehow the standart library very often. So it cannot be so bad. But standart librarys are mostly not so big, and then you will miss some footprints, if you go to the extremes. the annular rings are a good example. i used once the annular rings of a package from eagle, found, the annular rings where a little bit tiny and not rugged enough, and created a package with bigger annulars and also a bigger drill, because for repair, i got a problem to fit the new device into the old hole, because the copper clad inside the hole was know cladded with lead, too, and i goot moch work to clear the hole so good, that the new device would easily fit. But then i got a work with space problems.....and i created a package with even smaller annulars i kicked away bevore..... > - Things not meeting PCB manufacturers' requirements. Differing ideas > on whether the drillsize in the NC file is the final size after THP or > the pre-THP size, design rules for pads and so on. There schould be some defining lines somewhere in the library. best with pure text, so everybody with an editor could read it. for people liking GUIs it would perhaps nice to open a window to read this comments. > - Silkscreen on top of pads. I mean, seriously. Scraping silkscreen > off PCB pads is NOT fun, and soldering to a silkscreen-coated pad is > close to impossible. The EAGLE libraries (even the Cadsoft-created ones) > are especially guilty of this, but most CAD vendors appear to have done > it at some point. O yes. Not every manufacturer i able to make PCBs with silkscreen, but not printing the silkscreen across a pad, if someone created this.... Different layers for copper and silkscreen are mandatory, but there should be some funktion, computing the silkscreen away, if there is a pad. > > What I was thinking about doing is writing a small-ish program that > took a list of components to generate, like this: > Here i have to shut my mind....i am not a programmer.....i only dream to lern programming. ;-) > ... and use a set of templates for each component type to generate the > component footprints. You could link a symbol to a group of alternative footprints like eagle does it. But this should not be mandatory. Perhaps an far away footprint would fit....so i would prefere it like here in kiCad to choose an footprint free.....you should also be able to force footprints, who would not fit really, because perhaps you will use a transistor as a Diode, and therfore use only two pads of thre and a diode symbol...... And than there are symbols wit only one pin at the schematic, but 16 pins at a footprint, for big currents..... You should bee very, very free at this point..... >You still have to build the schematic symbols > manually (it's hard for a computer to figure out where best to put the > pins, unless they're just laid out in a grid on a rectangular outline) > but the footprints are generated by computer, and thus the pin numbers, > silkscreen and pad sizes/types can conform to IPC, ANSI, IEC or whatever > standard or house style you like. Yes. > What I'm ultimately thinking of is a "basic" component library that > covers 80% of use cases -- you're still going to have to tell Kicad what > the PIC12F508 looks like on the schematic, but at least you can use the > footprint generator to make the DIP8 package for it. > DIL or SOIC IC footprints are a smaller problem, because there is a very limited number starting at 4 and going to several doutzend. some are extra wide..... > Does anyone think this sounds like a good idea, or am I wasting my time? No. this is a very good idea. But you should be a little bit careful by creating entire packages from symbol up to footprint. Linking symbol and footprint should only be a suggestion, not mandatory. You have to be free in choosing footprints. And think about. Not all People are doing microcontroller stuff. Some are alo fiddling around with power ellectronics. dont forget them. :-) With best regards: Bernd Wiebus Bernd Wiebus Weezer Str.5 47589 Uedem Germany bernd.wie...@gmx.de -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01
