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 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 _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
