Hello Everyone, Please help, Can Anybody explain why too much voiding occurs when two metal is joined (Top Metal and Bottom metal)? Eventhough the peak temp is 40 C over than the liquidus temp of the solder. When a solder is reflowed without top metal the solder wetting is very good and the appearance is shiny. But when you put a top metal to be joine and then X-ray, there are a lot of voids. I tried to removed the top metal, and the picture below showed a lot of voids. Another thing is the color is not shiny but grayish. (Embedded image moved to file: pic29915.pcx) The paste is 85Pb/10Sb/5Sn Peak temp is 290 C Oven: Conduction Time until the unit is out: 180 Seconds. Many thanks to everybody. Sincerely Jonathan --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------