mhough wrote:The 45 deg trace rules.... Please elaborate on the rule.. Is 45 deg top and bottom the norm? I also tweaked a few traces using a different grid to the autorouter so they are a bit wonky... again, its a proto
AFAIK 45 degree trace design rules date back a long time, and relate to PCB production yields. I've heard two reasons:
(1) Manual tape-on-mylar PCB design. The sticky black layout tape would be cut by hand to approximately 2/3 width and sent in a new direction on a 45 degree bend. This junction insures the cut line wasn't exposed and become etched (thus creating an electrical failure).
(2) The 45 degree corners prevent etchant from building up as the board is aggitated (vertically), thus undercutting the metal, and again resulting in electrical failure.
Most likely these rules have been made obsolete by better process control. I've found that 45 degree corners (in CAD layouts) increase the trace density, improve route paths (when manual routing) and make the finished board design easier to visually check. Obviously, random trace placement will also work as long as it passes DRC.
In my own work I've found numerous errors on a 'finished' layout by running the DRC a second time with the 45 degree rule turned on, so I always apply 45 degree corners manually from the start.
mhough wrote:So aside from a few cosmetic issues the image isnt expected to reveal all holes and via's?
Correct! Okay on the other points, it's your board and you set the standards for appearance and content.
Good Luck! Comments Welcome!