Steve I agree with your assessment that the reduced trace height violates the requirements of IPC-6012. My experience is that this is probably not the only spot on the board or in the manufacturing lot. You should give everything in that shipment (from the same date code) a through examination. Given both the reduced conductor thickness and the spacing violation in a small area, I suspect that the problem was caused by plating resist. I don't know of an easy way to determine if this is localized to one spot on one panel or if it exists throughout the lot. If you have a decent relationship with the fabricator, you can ask if they had fall-out or ask for a copy of their manufacturing records to determine if other parts were scrapped. Most fabricators keep accurate records of pieces started and quantity scrapped for every lot. I've known design engineers (on a good day) to buy off a board like this. Personally, I wouldn't because it's too difficult to inspect 100% of the surface after the components are mounted, and there's a chance that a defect falls in the land/barrel junction area. To answer your other question regarding the outer layer copper thickness: The call out appears to be in error. The fabricator has to start with copper on the outer layer (usually 1/2 or 1 ounce) then plates copper in the holes and on the surface. Generally, if a fabricator plates 0.001 inch in the holes the surface will end up with an extra ounce (0.0013 to 0.0014) on the surface. (This is a generalization that does not apply in all cases.) Don Vischulis -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory Sent: Wednesday, May 28, 2003 12:53 PM To: [log in to unmask] Subject: [TN] Trace thickness problem... Hi all! I'd like your opinion on something. We're building a prototype assembly for a customer, and discovered something at final inspection that we didn't see when we received the bare fabs. We ordered 16-boards in four, 4-up panels. We found a trace that has a spot where it looks like it didn't plate up during final plating. Take a look at "Trace Thickness" at http://www.stevezeva.homestead.com There's 4-boards we've found that have this problem, 1 on one panel, and 3 on another panel, and of course they're all built up. The 6012 says that thickness can't be reduced by more than 20% of the minimum conductor thickness. I can't really tell if it's 20% or 50%. I've sent pictures both to our customer and the fab vendor. The customer wants the spot repaired, and there are a number of ways to do that. The fab vendor says it's not a problem because the stack-up drawing calls out 1-oz. copper after plating on the surface layer, and they said that there's more like 2-oz. on the surface layer, so there shouldn't be any problem, at least that's what I was told, I didn't speak to anyone directly. The stack-up is on my page too, look at "Stack-up"... The first question that comes to my mind, if 1-oz after plating was called on the stack-up, why was 2-oz plated? Or is that normal?. The drawing references our customers internal spec for fabrication, but it uses MIL-PRF-55110 for references. What are your opinions about this? Thanks everyone! -Steve Gregory- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------