-----Original Message----- From: Hooper Doug <[log in to unmask]> To: [log in to unmask] <[log in to unmask]> Date: Friday, July 03, 1998 10:20 AM Subject: [TN] Au/Ni/Cu PROBLEM I am experiencing a problem with my Au/Ni/Cu circuit boards. During the cleaning process in warm (120f) DI water some of them are exhibiting a "contamination". In certain areas (random) I am getting a discoloration on the pads. These are non-soldered connections of the board. Other areas on the board are soldered (hand) and have excellent solderability/wettability/solder coverage are generally bright, smooth and shiny. Sometimes this does not occur until the assembly has been washed 3 or 4 times throughout the production process. The discoloration appears brown, orange (like rust) and even dark blue to black. It also appears to be removed with an eraser. Does anyone know what is going on that would cause this condition to occur? I am concerned about the condition with respect to contact resistance (keypad/dome application). Will it get worse even if I can rub it off? My circuit board supplier is on plant shut-down today. Any input on this matter would be greatly appreciated! Technet or otherwise. Douglas A. Hooper, Sr. Process Engineer Luminescent Systems, Inc. [log in to unmask] (716)655-0800 x163 (716)655-0309 fax ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ Doug, Almost certainly your cleaning is insufficient. Can you get your water up to 150 deg F? This is considered a safe setting for a home water heater so it should be ok for your equipment. You might also consider increasing your dwell time in the cleaning cycle. Possibly you can increase the pressure of impingement of water on your boards, also. Make sure your reflow profile is not too hot in terms of length and top temperature, this can burn the flux components, especially in a paste. Also check the temperature of your wave solder. If all else fails or doesn't apply, try a different flux or paste. If you are running mixed technologies make sure your paste and wave solder flux are compatible. Some are not with components reacting to give insoluble residues. Frank Komitsky, Jr. ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################