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Re: KLC - courtyard

 

Hi Carl,
When I am back home, I will dig through my old pro stuff to get some data. my usual source was BellCoRe
documentation, but right now the exact reference number escape my memory. It might be with a 76 in it. I will confirm later as I left the telecom industry 10 years ago.

Regards,
Jean-Paul
AC9GH


> On Jan 10, 2015, at 10:10 PM, Carl Poirier <carl.poirier.2@xxxxxxxxx> wrote:
> 
> 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, 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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> 
> 



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