Hi Paul, Years ago [Once upon a time....!?!] there was an IBM paper [from a MN location, I think—don't ask me for a reference], that showed that you had to have a 90% physical separation crack to result in a 10% resistance increase. This has been confirmed less rigorously many times—that is why you had so many people wondering about your statement. Werner -----Original Message----- From: Paul Reid <[log in to unmask]> To: [log in to unmask] Sent: Wed, Aug 18, 2010 9:28 am Subject: Re: [IPC-600-6012] opinion poll Hi Werner, A number of defects like that still caused a 10% change in resistance. Crack or separation not withstanding, objective measurement of resistance change trumps the more subjective microsection evaluation. Maybe we are on the wrong angle to see the full extent of the damage. I do know that small corner cracks have produced large changes in resistance. Failing corner cracks may or may not extend across the full thickness of the copper. Sincerely, Paul Reid -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier Sent: August 17, 2010 8:22 PM To: [log in to unmask] Subject: Re: [IPC-600-6012] opinion poll Denise/Paul, I am with Denise on this one-twice. First, this separation would never cause a 10% resistance increase even if it goes around all 360 degrees. Second, this is not a crack, but a separation. Werner -----Original Message----- From: Denise Chevalier <[log in to unmask]> To: [log in to unmask] Sent: Tue, Aug 17, 2010 2:25 pm Subject: Re: [IPC-600-6012] opinion poll Again I am not sure I would call this a crack. The initial deposit is not connected to the foil (rounded) but does not appear to have "cracked". I am also surprised you lost 10% resistance due to this defect. It appears you have plenty of connection from the surface into the hole wall. Are you sure this was the cause for the loss of resistance? Denise Denise J Chevalier Amphenol Printed Circuits Quality Engineer Phone - 603-324-4530 Fax - 603-386-6442 CONFIDENTIALITY NOTICE: This email message, including any attachments, is for the sole use of the intended recipient(s) and contains confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please reply to the sender by email and destroy all copies of the original message. -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Paul Reid Sent: Tuesday, August 17, 2010 2:04 PM To: [log in to unmask] Subject: Re: [IPC-600-6012] opinion poll Here is a corner crack that produced a 10% increase in resistance. I don't know if the attachment will make it to the forum. I am CC Chris with this incase it does not get posted. We are having problems with our email. Sincerely, Paul Reid Program Coordinator PWB Interconnect Solutions Inc. 235 Stafford Rd., West, Unit 103 Nepean, Ontario Canada, K2H 9C1 613 596 4244 ext. 229 Skype paul_reid_pwb [log in to unmask] <mailto:[log in to unmask]> -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Francis Byle Sent: August 17, 2010 1:30 PM To: [log in to unmask] Subject: Re: [IPC-600-6012] opinion poll Careful, you'll give Chris a big head... -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Brown, Elaine Sent: Tuesday, August 17, 2010 12:25 To: [log in to unmask] Subject: Re: [IPC-600-6012] opinion poll Indeed I am confident enough in Chris's knowledge of 6012 that we would not be having the discussion if it were not visible before microetch, then the microetching must be done to assess whether the separation extends beyond the plane of the foil, which it does. -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Monarchio, James Sent: Tuesday, August 17, 2010 12:12 PM To: [log in to unmask] Subject: EXTERNAL: Re: [IPC-600-6012] opinion poll I agree with Matt, you need to determine if there is indeed separation first and inspection without etching is a good way to do it. Jim -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Byrne, Matthew J (US SSA) Sent: Tuesday, August 17, 2010 8:54 AM To: [log in to unmask] Subject: Re: [IPC-600-6012] opinion poll The possibility of a separation at the knee between plating layers needs to be evaluated without microetching the cross section mount. If no separation is found then no defect should be called out. Microetching helps in failure analysis. Matt Byrne Manufacturing Engineer, PWB Technology BAE Systems, Room 795 600 Main St, Johnson City, NY 13790 607-770-2267 [log in to unmask] -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Brown, Elaine Sent: August 17, 2010 6:27 AM To: [log in to unmask] Subject: Re: [IPC-600-6012] opinion poll It is non-conforming for both the crack and the plating separation. The second picture is not so clear cut. If indeed the area at the knee is separation it is rejectable. If it is differential microetching, it is not. Hard to tell from the photo. I do not think we have any criteria for burning. Elaine -----Original Message----- From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris Mahanna Sent: Monday, August 16, 2010 1:19 PM To: [log in to unmask] Subject: EXTERNAL: [IPC-600-6012] opinion poll Hi Everyone, Attached is a picture of a thru-hole corner after thermal stress. The plating is pulse. I believe the corner was 'burnt' because of the geometry of the (conformant) negative etchback. All the corners show burn; some show blisters; only this one cracked. In your opinion, what are the non-conformance(s) if any? Thanks Chris ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ NOTICE: This email message is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------