a few questions: -exactly WHAT get tarnished, dielectric, copper, solder? -WHAT will be "grounded"? -you can't decide RF ground with a multimeter. -WHAT microwave product do you work with? Sometimes, a board in a microwave set is not a RF board at all, but driver or logics etc. Inge -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Kong Hui Poh Sent: den 12 december 2007 13:43 To: [log in to unmask] Subject: Re: [TN] Tarnished on the bottom side (Teflon Board) Hi Technetterers, I am facing with board that after reflow, it turned tarnished. The board is of tin-lead plating. The top side of the board consists of the circuitry & components. The bottom side of the board is a complete plane. My customers said that there will be grounding due to the tarnished. However, I try using Multimeter, and probe the bottom side very lightly. The measurement I got is less than 0.5 Ohm. Somehow, the measurement shows otherwise. I wandered if there is an issue with the grounding if the board is tarnished. Can someone advise me if any of the IPC spec states that board of tin/lead plating, if found tarnished is a reject/defect. Is any of the IPC spec. defines the solder surface requirement for the Microwave end product (if after reflow). Thanks you in advance. Regards, Poh --------------------------------------------------- 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 -----------------------------------------------------