kicad-lib-committers team mailing list archive

[Carl Poirier <carl.poirier.2@xxxxxxxxx>]

Hi Jean-Paul,

Thanks for the information. I have looked at some videos. Are you aware of
some guidelines for THT courtyards?

Also, to answer Michal's question about the courtyard of 0204 SMD
resistors, IPC-7351 states a nominal courtyard excess of 0.15mm. See here
<http://pcbget.ru/Files/Standarts/IPC_7351.pdf>, page 13. The KLC can be
amended

On Sat, Jan 10, 2015 at 9:13 PM, Jean-Paul Louis <louijp@xxxxxxxxx> wrote:

> I have not followed the discussion very closely as I am away from home
> until end of January, but I would like to make a comment as I see that a
> lot of people are confused by te concept of courtyard. The confusion  is
> very understandable as since the advent of SMT, the courtyard is very close
> to the size of the component.
> To really understand the concept, one must understand how the parts are
> placed on a PCB during the assembly process. Most of the SMT devices are
> placed using a vacuum nozzle that is much smaller than the part. So the
> courtyard is only needed to make sure that you do not place a part on top
> of another. When using automated TH placement, the situation is a lot
> different as the machine use grippers instead of vacuum nozzles, so you
> need a lot more room around a part to avoid interference with the placement
> tools.
> To understand better, google terms like VCD, Radial Inserter, DIP inserter
> as there are a few videos showing these processes.
>
> Just my $0.02,
> Jean-Paul
> AC9GH
>
>
>
> > On Jan 10, 2015, at 5:41 PM, Carl Poirier <carl.poirier.2@xxxxxxxxx>
> wrote:
> >
> > I was also thinking about C), but discussing it is a good idea.
> >
> > As for the appropriate measurement, let's make sure we all agree. What
> about the courtyard clearance being measured from the edge of the
> silkscreen to the center of the courtyard line? There should thus be no
> overlap.
> >
> > Also, THT components and connectors can be at 0.5mm clearance.
> >
> > Any comments?
> >
> > On Sat, Jan 10, 2015 at 4:18 PM, nnn <nnn4000@xxxxx> wrote:
> > The rule 6.6 is not clear for me.
> >
> > It's clear that for most of smd components the courtyard should be 0.25
> mm from pads.
> > What rules aplly when courtyard isn't determined by pads?
> > a) should it be 0.25 mm from silkscreen?
> > b) should it only enclose silkscreen?
> > c) should it be 0.25 mm from package body and then enlarged to enclose
> silkscreen (if necessary)?
> > I think the c) is best but it's not defined in convention.
> > In cases b) and c) courtyard will be very close to silkscreen. Should it
> be allowed that centre of courtyard line lay on boundary of silkscreen line
> (0.025 overlap)? Courtyard is area limited by the line, so it seems that
> the 0.025 mm overlap should be allowed, but it may look bad.
> >
> > Line width for courtyard (0.05) should be defined in convention.
> >
> > The same clearance for 0204 SMD resistor and 5 W THT resistor is
> probably bad idea, exactly that electrolytic capacitors has bigger
> courtyard because of bigger placement tolerances. Is there any reason for
> using bigger courtyard for THT electrolytic capacitor than for eg THT
> radial chockes? Why connectors should have bigger courtyard than eg
> mechanical switches?
> > In document:
> http://www.dnu.no/arkiv1/The%20CAD%20Library%20of%20the%20Future.pdf
> > in chapter 10.3 it's suggested that it's difficult to determine
> courtyard for THT.
> >
> >
> >
> > W dniu 09.01.2015 o 20:21, John Beard pisze:
> >
> > On Fri, 2015-01-09 at 17:54 +0100, nnn wrote:
> > There is no information about courtyard line width in kicad library
> > convention.
> > Can it be 0.05 mm as suggested in:
> >
> http://www.pcblibraries.com/downloads/temp/PCB_Design_Optimization_Starts_in_the_CAD_Library_8685831.pdf
> > ? I used 0.05 eg in Housings_SSOP, so you can check if it looks ok.
> > Sounds very sensible to me. Since the guy who wrote that is also one of
> > the people on the committee that approved IPC-7351, this is presumably
> > consistent with that standard.
> >
> > Can overlaping courtyard with silkscreen be allowed? It may look bad,
> > but it's not specified in rule 6.6.
> > As the "IPC" way now is to draw the main silk screen lines at the
> > maximum material position for alignment verification purposes, and the
> > courtyard by definition is outside that, I think it would make sense to
> > at least say that all silk should be contained within the courtyard?
> > Otherwise it could be obscured by other components. If the silk extends
> > up to or outside the courtyard, that may indicate that the courtyard is
> > too tight.
> >
> > Cheers,
> >
> > John
> >
> >
> >
> >
> >
> >
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