Den 26/11/2014 20.29 skrev "Adam Wolf" <[email protected]>: > > Nick, > > I have used trapezoidal pads to connect between PCB antennas and traces. There are precise rules on trace thickness for antennas, and this let me have one thing I could modify in the footprint to handle multiple different feedline widths.
Yes, this is what JPC pointed out. The issue here as I understand is weather it should support trepez fill, instead of the rectangular zone fill we see now, or not. > > Adam Wolf > Cofounder and Engineer > W&L > > On Wed, Nov 26, 2014 at 1:16 PM, Nick Østergaard <[email protected]> wrote: >> >> 2014-11-26 20:00 GMT+01:00 jp charras <[email protected]>: >> > Le 26/11/2014 18:43, Nick Østergaard a écrit : >> >> This is indeed an annoyting bug, it has existed since 2009 at least. >> >> There is already a bug report about it. See: >> >> >> >> https://bugs.launchpad.net/kicad/+bug/1035621 >> > >> > Sorry, but I already said why a trapezoidal pad is designed. >> > >> > The fact an user is thinking something is not expected is not a proof of >> > a bug. >> >> I do follow you, but I still thought it was worth linking this thread >> with the bug report. >> >> > Trapezoidal pads have a very specific purpose. >> > I am pretty sure a copper zone around tracks in a microwave design >> > breaks the design. >> >> Indeed, IIRC this special behaivour of the trapez pad is not described >> in the manual, so one could only assume it was a bug. >> >> On top of my head I can not come up with a design that requires a >> trapez pad instead of an oval, rectangular or circular pad. Maybe >> wayse could fill in, since he has them in his design. >> >> > So : >> > First, define the purpose of trapezoidal pads. >> > After, and depending on this purpose, decide if thermal reliefs are good >> > or not. >> > >> >> >> >> Nick >> >> >> >> 2014-11-26 18:03 GMT+01:00 jp charras <[email protected]>: >> >>> Le 26/11/2014 17:18, Wayne Stambaugh a écrit : >> >>>> I just discovered something I never noticed before. Trapezoidal SMD >> >>>> pads are not connected to zone files (see attached screen shot). The >> >>>> zone fill also does not follow the contour of the pad outline. Is this >> >>>> by design or should I file a bug report? >> >>>> >> >>> >> >>> Currently, this is by design. >> >>> >> >>> The primary goal of these trapezoidal pads is microwave applications. >> >>> >> >>> For these microwave applications, they are used to connect a large track >> >>> to a narrow pin ( transistor or IC) ( or a narrow track to a large pin) >> >>> *without discontinuity* of the copper width. >> >>> (A discontinuity between a track and a copper pad area can create signal >> >>> integrity issues. In fact any discontinuity on the signal path creates >> >>> issues, at very high frequencies ) >> >>> A trapezoidal shape with an edge having the same size as the track, and >> >>> the opposite edge having the size of the transistor or IC pin does not >> >>> create discontinuity. >> >>> One could use also rectangular pads, and trapezoidal track segments to >> >>> avoid discontinuity, but Pcbnew does not know trapezoidal track >> >>> segments, mainly because they are not easy to handle in DRC. >> >>> >> >>> When you are using trapezoidal shapes for pads, you are expected connect >> >>> a track to these pads using the right edge, and the right track width >> >>> (or the right pad size) >> >>> If this is not the case, a rectangular pad or an oval pad is better >> >>> (more easy to use). >> >>> >> >>> Adding thermal relief to a trapezoidal shape creates discontinuity, and >> >>> the shape is no more a trapezoid. >> >>> In fact, using a trapezoidal shape for a pad in a copper zone has no >> >>> interest. >> >>> >> >>> For these reasons, I did not spent time to code thermal reliefs for >> >>> trapezoidal shapes. >> >>> >> >>> Of course, trapezoidal shapes can have now applications outside the >> >>> microwave applications, but I don't know these applications. >> >>> >> >>> -- >> >>> Jean-Pierre CHARRAS >> >>> >> >>> _______________________________________________ >> >>> Mailing list: https://launchpad.net/~kicad-developers >> >>> Post to : [email protected] >> >>> Unsubscribe : https://launchpad.net/~kicad-developers >> >>> More help : https://help.launchpad.net/ListHelp >> >> >> > >> > >> > -- >> > Jean-Pierre CHARRAS >> > >> > _______________________________________________ >> > Mailing list: https://launchpad.net/~kicad-developers >> > Post to : [email protected] >> > Unsubscribe : https://launchpad.net/~kicad-developers >> > More help : https://help.launchpad.net/ListHelp >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~kicad-developers >> Post to : [email protected] >> Unsubscribe : https://launchpad.net/~kicad-developers >> More help : https://help.launchpad.net/ListHelp > >
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