Hello Peter! There are several ways to skin this cat (plating-etch dilemma) and it depends on where you look for the answer. Short Term - Etch: Assuming there is some uniformity to the thicker copper plating it could be etched in a double pass Image-Develop-Etch-Strip-Repeat. We used to etch the outer portion of the core where the plating was thicker and then go back to etch the finer circuitry during a second pass. The down side was adding processing steps and more handling. Medium Term - Plating: If the plating distributions are design related then the plating line needs to be tweaked. Pulse and Reverse -Pulse Plating can do some amazing things but it takes development time to dial-in. Long Term Alt. Plating: There are alternatives to Electroless Cu that only plate the drilled hole not the surface copper. Where's Michael Carano hiding? He can answer that one in his sleep. And as you know, once it's over etched your done. Hans Integrity First - Service Before Self - Excellence in All We Do ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Hans M. Hinners Electronics Engineer Warner Robins - Air Logistics Center (WR-ALC/LUGE) Special Operations Forces System Program Office (SOF - SPO) Gunship Team 226 Cochran Street Robins AFB GA 31098-1622 mailto:[log in to unmask] Com: (478) 926 - 5224 Fax: (478) 926 - 4911 DSN Prefix: 468 -----Original Message----- From: <Peter George Duncan> [mailto:[log in to unmask]] Sent: Sunday, November 18, 2001 10:07 PM To: [log in to unmask] Subject: Re: [TN] Over-etch II Hi, Rudy, Assumption is correct - over-etch occurs in the same place on all boards of the same design, and is on the patterns. Masked traces are in good condition. Fab house has not suggested a change of design as a solution to the problem - in fact they didn't even want the over-etched boards back, so my belief is that they knew about the problem even before they shipped the product. I myself need to learn a lot more about what is a produceable design and what isn't as far as this sort of thing is concerned, though I would trust that our board designers should know more about that than I. They supposedly followed IPC-2221 & 2222 when putting the design together, but who knows what was missed (if anything). Does anyone else have this problem with boards with blind vias? Or if it's DFM'd, what steps were taken to avoid this issue? Best regards Peter Duncan "<Rudy Sedlak>" To: [log in to unmask] Sent by: cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST TechNet Aero/ST Group) <[log in to unmask] Subject: Re: [TN] Over-etch II ORG> 11/16/01 11:23 PM Please respond to "TechNet E-Mail Forum." This MAY be so simple, we will wonder why/how they did not see the problem... To understand this analysis/suggestion, you have to understand the difference between pattern plating (which is done after photoresist application) and panel plating (which is done before photoresist application). Again, I am grasping/guessing here, as I really do not understand the process well enough to give "expert" advice.... If they are doing a "selective" panel plate, which would make the Copper selectively thicker, this would be an obvious answer... I assume that the over etch problem occurs at the same place on all the boards of the same design? And it occurs on 100% of the boards of a similar design? (In other words, is the problem one of process/board design, or one related to equipment used in fabrication?) If the problem is not always in the same place, this would speak to equipment issues at their facility...and even if the the problem occurs at the same place on all boards, it could still POSSIBLY be equipment issues at the fabrication facility. Rudy Sedlak RD Chemical Company ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------- ----- [This e-mail is confidential and may also be privileged. If you are not the intended recipient, please delete it and notify us immediately; you should not copy or use it for any purpose, nor disclose its contents to any other person. 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