Re: [PEDA] Issue w/ lomax short Kelvin Paths and Copper pour
At 02:41 PM 5/14/2002 -0700, Dennis Saputelli wrote: could you repost your alternative? possible implementation: enable an unused mech layer and label it shorts. Add track on this layer to a jumper footprint so that it will short the jumper if added to the plot for the copper layer. Use the shorted jumper on schematics to isolate a net section (i.e., to control connection path). Create a separate gerber definition file under the CAM manager for the copper layer used which adds the shorts mech layer to the plot; disable plot for that copper layer in the regular CAM gerber definition file. If both definitions are enabled for plot in the CAM manager, both will be plotted. (Copy the main CAM def file to make the special one, then disable all layers except the one you want to plot and change the mech layer to plot simultaneously in on the mech layer tab.) I have not actually used this procedure, only the microgap virtual short, but it seems quite straightforward in theory. If anyone has used it, please confirm that it works or tell us how it didn't, if known. I would expect that the most likely failure would be that the designer forgets to set the special CAM definition, which would be relatively harmless at the prototype level since the shorting jumper could manually be shorted. (This is also the case with the microgap short). This, by the way, is a good argument for requiring the fabricator to provide its customer the actual CAM files used for fabrication. Fabricators routinely make small changes without informing customers in order to improve manufacturability But I've never seen a fabricator provide the actual files. In any case, the fabricator who unshorted the pads should very clearly have queried the customer as to whether or not the pads should be shorted (as they would if the board had been fabricated as-is) or opened to a fabricatable gap. So those missing shorts were due to fabricator error... i missed it i did find that origin pin 1 seemed to nail the issue and make no gap even in gerber 2.4 my gap was i think .005 mil in the (bad) case of using center origin and using gerber 2.3 i think the result was a 2 mil gap as the edges of the pads were pulled back toward the center to the nearest mil this notwithstanding it has proven to be a useful and clever tool Dennis Saputelli Abd ulRahman Lomax wrote: If gerber plots were not rounded off, there would be no problem with the virtual shorts, and, in fact, if fab houses fabbed the boards as-is without modifying the gerber, there would also be no problem. But Protel does some rounding and it is not easy to exactly control aperture assignments while using the much easier RS-274X, though it can be done; properly implemented, aperture match would cause the gap to actually disappear as long as the pad distance is such as to leave the pads on a 1 mil grid. But as Mr. Saputelli discovered, it is fairly easy to set up and place a virtual short footprint in such a way as to leave a tiny gap, enough to puzzle the fab house inspector. Complexities like this have led me to recommend the alternate method I indicated in another post in this thread. It is a little easier to document and no fab house will be tempted to modify the gerber. -- ___ www.integratedcontrolsinc.comIntegrated Controls, Inc. tel: 415-647-04802851 21st Street fax: 415-647-3003San Francisco, CA 94110 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Issue w/ lomax short Kelvin Paths and Copper pour
thanks for repost, i will consider this method yes the shop should have called, FYI it was Imagineering (not the first problem i have had with them) though in fairness their quality is adequate when considering the very fast turn and price Dennis Saputelli Abd ulRahman Lomax wrote: At 02:41 PM 5/14/2002 -0700, Dennis Saputelli wrote: could you repost your alternative? possible implementation: enable an unused mech layer and label it shorts. Add track on this layer to a jumper footprint so that it will short the jumper if added to the plot for the copper layer. Use the shorted jumper on schematics to isolate a net section (i.e., to control connection path). Create a separate gerber definition file under the CAM manager for the copper layer used which adds the shorts mech layer to the plot; disable plot for that copper layer in the regular CAM gerber definition file. If both definitions are enabled for plot in the CAM manager, both will be plotted. (Copy the main CAM def file to make the special one, then disable all layers except the one you want to plot and change the mech layer to plot simultaneously in on the mech layer tab.) I have not actually used this procedure, only the microgap virtual short, but it seems quite straightforward in theory. If anyone has used it, please confirm that it works or tell us how it didn't, if known. I would expect that the most likely failure would be that the designer forgets to set the special CAM definition, which would be relatively harmless at the prototype level since the shorting jumper could manually be shorted. (This is also the case with the microgap short). This, by the way, is a good argument for requiring the fabricator to provide its customer the actual CAM files used for fabrication. Fabricators routinely make small changes without informing customers in order to improve manufacturability But I've never seen a fabricator provide the actual files. In any case, the fabricator who unshorted the pads should very clearly have queried the customer as to whether or not the pads should be shorted (as they would if the board had been fabricated as-is) or opened to a fabricatable gap. So those missing shorts were due to fabricator error... i missed it i did find that origin pin 1 seemed to nail the issue and make no gap even in gerber 2.4 my gap was i think .005 mil in the (bad) case of using center origin and using gerber 2.3 i think the result was a 2 mil gap as the edges of the pads were pulled back toward the center to the nearest mil this notwithstanding it has proven to be a useful and clever tool Dennis Saputelli Abd ulRahman Lomax wrote: If gerber plots were not rounded off, there would be no problem with the virtual shorts, and, in fact, if fab houses fabbed the boards as-is without modifying the gerber, there would also be no problem. But Protel does some rounding and it is not easy to exactly control aperture assignments while using the much easier RS-274X, though it can be done; properly implemented, aperture match would cause the gap to actually disappear as long as the pad distance is such as to leave the pads on a 1 mil grid. But as Mr. Saputelli discovered, it is fairly easy to set up and place a virtual short footprint in such a way as to leave a tiny gap, enough to puzzle the fab house inspector. Complexities like this have led me to recommend the alternate method I indicated in another post in this thread. It is a little easier to document and no fab house will be tempted to modify the gerber. -- ___ www.integratedcontrolsinc.comIntegrated Controls, Inc. tel: 415-647-04802851 21st Street fax: 415-647-3003San Francisco, CA 94110 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Issue w/ lomax short Kelvin Paths and Copper pour
there is a 'issue' w/ the 'lomax short' of which you should be aware it bit me! (i forget if i already posted this) after using the lomax short without probs on several jobs, one day a board shop called and reported that there was a small gap between some pads, should they 'fix' it? i said no and forgot about it later on another job from a different shop they went ahead and 'fixed' them so they were all open (they didn't call to ask) now i started to wonder i examined the gerbers and sure enough i could see the small gap, but it should have been too small to render (dims as or similar to below) i thought maybe i used gerber 2.4 or 2.5 or something, but even these should have bled together after a lot of futzing i figured it out my original part had pin 1 as the origin later while cleansing libs to all have centroids as origin i did that one (the 'shorted' pads part) too when the origin is the centroid the gerber plotter will back off to the nearest mil or tenth mil depending on 2.3 2.4 etc this will create a gap solution, change the origin back to pin 1 and they bled together on the plot Dennis Saputelli [EMAIL PROTECTED] wrote: In a message dated 5/14/2002 5:27:28 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: I am fine tuning the PCB on an amplifier circuit. The circuit requires 'Kelvin' (or loner!) paths to components on the same nets as other paths. Obviously the autorouter puts them into the shortest path and I was wondering if there is a way to keep them seperate. This sounds like a perfect application for the Lomax virtual short which has been discussed on this board. Check the archives for details, but in a nutshell you create a part which has a gap which is too small to fabricate (i.e. 0.02), and set up a special design rule to allow a 0.01 clearance between the pads involved. Place a jumper on the schematic to allow the two wires involved to be separate nets, and place the physical component described above to control the connection point between the two nets. Steve Hendrix -- ___ www.integratedcontrolsinc.comIntegrated Controls, Inc. tel: 415-647-04802851 21st Street fax: 415-647-3003San Francisco, CA 94110 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Issue w/ lomax short Kelvin Paths and Copper pour
If gerber plots were not rounded off, there would be no problem with the virtual shorts, and, in fact, if fab houses fabbed the boards as-is without modifying the gerber, there would also be no problem. But Protel does some rounding and it is not easy to exactly control aperture assignments while using the much easier RS-274X, though it can be done; properly implemented, aperture match would cause the gap to actually disappear as long as the pad distance is such as to leave the pads on a 1 mil grid. But as Mr. Saputelli discovered, it is fairly easy to set up and place a virtual short footprint in such a way as to leave a tiny gap, enough to puzzle the fab house inspector. Complexities like this have led me to recommend the alternate method I indicated in another post in this thread. It is a little easier to document and no fab house will be tempted to modify the gerber. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Issue w/ lomax short Kelvin Paths and Copper pour
could you repost your alternative? i missed it i did find that origin pin 1 seemed to nail the issue and make no gap even in gerber 2.4 my gap was i think .005 mil in the (bad) case of using center origin and using gerber 2.3 i think the result was a 2 mil gap as the edges of the pads were pulled back toward the center to the nearest mil this notwithstanding it has proven to be a useful and clever tool Dennis Saputelli Abd ulRahman Lomax wrote: If gerber plots were not rounded off, there would be no problem with the virtual shorts, and, in fact, if fab houses fabbed the boards as-is without modifying the gerber, there would also be no problem. But Protel does some rounding and it is not easy to exactly control aperture assignments while using the much easier RS-274X, though it can be done; properly implemented, aperture match would cause the gap to actually disappear as long as the pad distance is such as to leave the pads on a 1 mil grid. But as Mr. Saputelli discovered, it is fairly easy to set up and place a virtual short footprint in such a way as to leave a tiny gap, enough to puzzle the fab house inspector. Complexities like this have led me to recommend the alternate method I indicated in another post in this thread. It is a little easier to document and no fab house will be tempted to modify the gerber. -- ___ www.integratedcontrolsinc.comIntegrated Controls, Inc. tel: 415-647-04802851 21st Street fax: 415-647-3003San Francisco, CA 94110 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
