Subject: Time:10:02 AM OFFICE MEMO ASSY: Non-wetting Date:4/23/97 Hello everybody: I have the following case study that I would like to share and get your comments before arriving to a conclusion. Problem: Non-wetting on 90% (RM0705) chip resistors (different values), 100% grainy solder joints on chip components (RM0705), ceramic flat packs show shiny and smooth solder joints on the same assembly. Non-wetting accentuated after second reflow. Process: -Vapor Phase (216oC) with infrared preheat system, Solder Paste Sn63/Pb37 RMA -Profile: shows that some Temp across the PWB were between 180oC to 187oC before entering to the vapor (reflow) Background & Tests: - Chip components belong to different lots (different values) but same part type - Lots are 2 year old!! -Termination: Metallization: fired platinum-gold, vacuum deposited nickel chrome, electrodeposited nickel, electrolytically deposited gold, and then coated with Sn60/Pb40 (QQ-S-571) -SEM/EDX results show oxidized termination (lead oxide) and traces of Phosphorus -Solderability test "Dip & Look" per ANSI/J-STD-002 using: R Flux: did not pass RMA Flux: pass Thank you in advance for any inputs, Gino Cochella (310) 814-3955 e-mail: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************