You can help out your board fabricator quite a bit by tear-dropping the pads at the trace entry point on the fine-line boards, especially if the holes are not proportionately small along with the lines (for example: 5mil spaces and 5mil lines, with 18mil holes- you're probably using conventional means to drill the holes, in this case). Your CAD or CAM system may well have a routine to tear-drop or "snow-man" the pads such that opens do not occur if there is some mis-registration or drill wobble. Its probably a good idea to use this feature. John Swinehart BFGoodrich Avionics Systems, Inc. >>> <[log in to unmask]> 07/21/97 02:37pm >>> Mike, I would estimate that 75%, if not more, of all fabricators in the states have the capability to fabricate .005 lines/spaces in a production mode. The problem may be with your fabricator. I'm not aware of of too many PCB shops that can not fab .005/.005. The game changes once you go beyond this point. I found most of my fabrication problems occured at .004/.004 and .003/.003 lines/spaces. What has successfully worked is .004/.006 lines/spaces, respectively. The spacing is the driving force behind getting good conductor walls and minimizing overetching. The additional spacing allows for the etch chemistries to sufficiently etch copper in the tracks (valleys) and be replinished efficiently. The chemistries used to etch are isotropic, meaning they etch in all directions proportionally. What I observed on .003/.003 and .004/.004 lines/spaces is severe undercut, conductor slivers and bridges. This is not to say .003/.003 and .004/.004 lines/spaces can not be obtained. The fabricator must have the necessary equipments, chemistries and process controls in place to do so. I know of several in the inductry that are fab'ing .003 and .004 lines and spaces in volume, but at a premium. If you need assistance, I can probably recommend several fab houses in your region for your current .005/.005 requirement. Hope this helps. John Gulley Inet Inc 1255 W. 15th St Plano, TX 75075-7270 ______________________________ Reply Separator _________________________________ Subject: Standard PCB/PWB Trace Width's Author: "Michael Forrester"<[log in to unmask]> at Internet Date: 7/18/97 5:38 PM We currently design boards with 8 mil. traces. We have recently tried to go to 6 mil. traces and found that we had reliability problems from batch to batch. What is the smallest trace that is considered reliable by todays standards? Is it just our PCB/PWB manufacturer that may have a problem. Typically what we saw was over etching of the traces. Thank you. Best Regards, Mike Forrester LeCroy Corp. [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************