Stuart, Thank you very much for your suggestions. details follow... On 4/30/05, Stuart Brorson <[EMAIL PROTECTED]> wrote: > Hi Vax 9000, > > So I looked at your Gerbers again after you posted the whole set. > Overall I am very impressed. I suspect that this is not your first > board!
I did two or three loose TTL boards ten years ago with Tango. I think I am a newbie again after so many years! This time it is a very tight board with high density chips and chips with fast edges that are totally new to me. > > Some comments: > > * As far as I could tell, you did a great job with all manufacturing > tolerances. I checked your design against the tolerances listed on > the Advanced Circuits webpage: > > http://www.4pcb.com/fast_design_quote_online_pcbs_tolerances.htm > > Solder mask and solder paste look fine to me. However, did you check > the drill diameters against your PGA and DIP pin diameters? I don't > recall a typical pin diameter; your drill diameters are .029. Is this > enough? Thank you for your suggestion. I will check the pins I have to make sure that they fit. > > * Finally, your fab drawing shows the outline of the board extending > waaaaay below the actual edge of the board. You may want to examine > this yourself. PCB autogenerates the fab drawing based upon the > active drawing area you used when laying out the board. I suspect > that you extended the drawing area down when you were working. You are correct! I used the area to rotate parts, and to bring up parts from foo.pcb.new. I forgot to resize the board though. > > The problem is that your board is not a simple rectangle. I suspect > that you actually want to route out along the silkscreen outline of > the board. The problem is that PCB has autogenerated your board > outline in the fab drawing assuming that it is the rectanglular > drawing area. PCB developers: this is a misfeature, IMHO. I supposed that the silkerscreen out line is the board outline. I will follow other's suggestion to use a outline layer. vax, 9000 > > In commerical tools, you would have a separate layer calling out the > board outline. For PCB, you probably need to put a manual instruction > somewhere for the fab house to route the boad along the silkscreen > outline. Maybe you can draw your desired outline on a new, separate > Gerber layer? Alternately, you can make a mechanical drawing of the > desired board outline, and include it with your design materials. > Don't forget to make it *totally* clear where the holes and outline of > the board lie w.r.t. the positions of the features in teh Gerbers. If > you can speak to an engineer at the fab house in person, that would > help you clarify exactly what board outline you want. Otherwise, if > the fab house operates "open loop" (like many of the el-cheapo places > do) then you will get back a rectangular board which you will have to > rework yourself. > > Others, any opinions about how to create complex board outlines in > PCB? > > Stuart >
