Someone with less scruples or sophistication than me might infer you are using smear tactics to get new business. Dewey -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /* Sent: Thursday, August 07, 2008 11:26 AM To: [log in to unmask] Subject: Re: [TN] Smear and rework failure Hi Pradeep, NO, smear will not form uniformly. YES, smear will affect the quality and reliability of the PCBs at every stage of subsequent work and operational use. THEREFORE, effective desmear is a must. HOWEVER, that does not mean that you need a lot of positive etchback, because that too degrades quality and reliability. You need to be aware that desmearing Pb-free soldering compatible PCB base materials, typically phenolic cured, do not respond to smear removal like the traditional FR-4 PCBs. All of this, and of course much more, is detailed in my White Paper "Recommendations for PCB FAB Notes and Specifications in Printed Circuit Board Drawings for SnPb and Lead-Free Soldering Assemblies, the Qualification of PCB Shops and Activities to Assure Continued Quality." Werner Future workshops: Reliability Issues with Lead-Free Soldering Processes, September 22, Schaumburg Failure Mode and Root Cause Analyses Reliability (Fatigue, Brittle Fracture, ENIG), September 22, Schaumburg Solder Joint Reliability: Parts 1 & 4, Oct. 9, Moscow, Russia Solder Joint Reliability: Part 4, Oct. 17, Timisoara, Rumania Solder Joint Reliability: Parts 1 & 4, Oct. 22, Tallinn, Estonia ************** Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos. (http://autos.aol.com/cars-BMW-128-2008/expert-review?ncid=aolaut0005000 0000017 ) --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------