I, as a beginner, would like a few more answers. 1) How should be handled when a board design requires both Au wire bondings and a solder reflow. Those two areas are about 50-100 mils away from each other. I do need a Au finish on wire bonding area obviouly. How about solder reflow areas?? Can't I have the Same Au finish thoughout the board??? > Beside gold thickness, the amount of solder applied should also be > considered. Per IPC-D- 279, "Design Guidelines for Reliable Surface Mount > Technology Printed Board Assembly", Section 5.4.4. where gold or palladium > plating is used, the gold or palladium content in the solder joint should be > approx 3 %wt. or less. Here are our thinkess rules for Gold. > > Electrolytic AKA hard gold: Mostly for Wire bond > Elecrtroles AKA Soft gold: Common 15 to 25 u" as long as it follows the 3%wt > rule > Immersion: Common 5 to 10 u" (Preferred in SMT assemblies, except edge > finger connector) > > To calculate the weigth factors, these number might help > Density of Gold = 19,300 kg per m3 > Density of Solder = 8,500 kg per m3 > > Please ensure to have at least 100 u" of Ni beneath the gold. > > > Hope that helps > Michael Yuen > > ################################################################ > 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 t ext in the body: > To subscribe: SUBSCRIBE TechNet <your full name> > To unsubscribe: SIGNOFF TechNet > ################################################################ > Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional inf ormation. > For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509 -9700 ext.311 > ################################################################ > _________________________________________________________________ Masatoshi (Bro) Suzuki | Maxtek Components Corp. | Email: [log in to unmask] P.O. Box 1480, M/S 13-035 | Voice: (503) 627-4025 Beaverton, OR 97075-1480 | Fax: (503) 627-4651 _________________________________________________________________ ################################################################ 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 web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################