Hello Fabio. > > Personally I don't like lots of filled zones unless that really are > > necessary, but that's a fairly minor point. > Well, I read that this is good practice as this make less use of > etchant during the etching process. Isn't that true?
Actually it IS a good practice to use filling zones. Not only for saving etchant but also for grounding, shielding and low resistant power supply. For electromagnetic compilance zone fill is essential. But you have to be carefull. Some structures, as an example long singular fingers or slots, are prone to get resonant and producing additional RF Problems. You can also get isoliting problems, and low ground conection losses for power supply means also high shortcut currents. Sometimes you get even additional heat by eddy currents. So you have to look for this issues. In my experience, you can look for this long structures and try to get them small or remove them complete. To get them smaller you can add bridges to the design. As an example, if you have a long slot by a long shaped socket, try to shortcut this slot by connecting it at one or severall places from one side to the other. Try to connect each zone with more then one (better more than two) connections to its potential. This connections should be spaced. As an example at opposite corners of the zone. Often it helps, to put additional GND vias to the board for creating additional zones of GND potential. So you get a unregulary grid of Ground zones and interconnections of them at your board. If some ground zones are covering the same area at opposite sides of the board, connect them with vias (stitching). Try not to place this stitchings regulary, because any regularity could get resonant, but try to place them randomly. This will avoid to create some resonators. As an example, you have a line of 100mm where the ground zone covers both, the primary and secondary side of the board. So you want to stitch them together by vias through the board, and the vias schould be spaced equal acros this line, perhaps at 1/3 and 2/3 of the line. But DO NOT place the vias at 33,3mm and 66,6mm, because you have a regular structure of following 33,3mm parts, which can resonate together. The better solution would to place one via at 30mm and the next at 80mm. so you have three parts with different lengs 0f 30, 50 and 20mm, which can only resonant individual. If you think, 50mm is too long, put an additional via to divide it. But not ecactly at the middle. ;-) also do not place the vias in an exact straight line. Move them randomly out of the center of the line. Vias are expensive, if you designe for a great quantity of boards. Also it consumes much time to create this fill zones carefully. So i can understand Andys suggestion to avoid them. Especially if you have to save room for isolating issues. I have not tested yet, wether stitching works at KiCAD. ;-) Up to now, the remaining vias of the ground net created enough vias for my simple cases. With best regards: Bernd Wiebus alias dl1eic
