At 08:16 AM 5/17/2002 -0700, [EMAIL PROTECTED] wrote: >4. It is good practice to provide fabricators with your whole design or at >least the .pcb file because often slight corrections are necessary to be >made just to adapt the pcb to their technologies, and let them generate >files and reports they need.
From an individual fabricator's point of view, this may be true, though the fabricator increases the risk of error by modifying design files, that is, the risk of error for which the fabricator will be held responsible, which could be very, very expensive. We have seen in recent threads where fabricators made incorrect assumptions about design intent. The raw PCB file, in my opinion, should not, under normal circumstances, be provided to the fabricator. It belongs with design engineering. Yes, fabricators may wish to make certain modifications in the files in order to end up with the nominal track sizes, for example, after the etch process behavior is considered. But this is a geometric modification and can readily be done in a CAM program, so the fabricator only needs the gerbers. The supplied gerbers should show nominal dimensions indicating the desired finished result, not necessarily what will actually be plotted. For example, I may specify an 0.028 hole and that is what will be in the PCB file, but the fabricator will probably drill the hole at 0.031 to allow for the thickness of the plating. So the fabricator will modify the files according to the needs of the fabricator's process, which may vary from fabricator to fabricator. If the relationship between the fabricator and the designer is close, possibly the fabricator might have the PCB file, but would not have the authority to modify it in a permanent way. Anomalies found by the fabricator should always be queried to the designer even if they seem easy to fix. One person's anomaly can be another person's special design condition. Abd ul-Rahman Lomax LOMAX DESIGN ASSOCIATES PCB design, consulting, and training Protel EDA license resales Easthampton, Massachusetts, USA (413) 527-3881, efax (419) 730-4777 [EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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://email@example.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *