--- In [email protected], Robert <birmingham_spi...@...> wrote: > > I routinely have to route boards that use a chip with an MLF footprint. > This is a pain when manual routing because the clearance has to be > dropped from 12 thou (US "mils") to 6 thou when connecting or editing > tracks attached to its pins. However, I don't want to do the whole > board at 6 thou because it's unnecessarily risking inter-track shorts. > > I would like to be able to use the Freerouter autorouter so I don't have > to spend so much time routing. That means I need to somehow be able to > tell Freerouter to use 6 thou for the MLF device and 12 thou everywhere > else. It will AFAIK do this (if I define a clearance class "mlf"), but > kicad seems to export tracks with just one track clearance, "default", > which of course I want to have a clearance of 12 thou. I can't find > find a way to manually define another track class and tell Freerouter to > use it for the mlf pins. > > I'm currently experimenting with fanning out the pins on the mlf device, > but of course the direction chosen inevitably isn't optimal and then the > autorouter ends up stuck. > > I would appreciate any suggestions on how to solve this problem. If I > manage to find a solution I'll post it. > > Regards, > > Robert. >
In the Freerouter it is possible to assign clearance classes even to single objects. For your purpose you can do the following. In the Pulldown menu of the Freerouter choose Rules | Clearance Matrix. In the clearance Matrix sheet, that pops up, push the Add Class button to create a new clearance class with name MLF for example. Change the entries in the column or row of the new class MLF in the clearance matrix to your desired values. Then select your critical pins on the board and push the Clearance button in the toolbar to change the clearance class of your selected objects to the new class MLF. You can select your critical pins individually with the left mouse button or by dragging a rectangle. You can also select your critical objects with Info | Placed Components or Info | Library Packages in the pulldown menu, choosing your components or packages and then pushing the Show button. To check that your changes work as desired, you can do some manual routing in the neighborhood of your critical pins. Regards, Alfons
