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. Trapezoidal pads have a very specific purpose. I am pretty sure a copper zone around tracks in a microwave design breaks the 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
