You have a problem with outgassing volatiles. The gas movement in the voids keeps the solder moving until solidus, which causes poor grain structure that weakens the joint. The poor grain structure is less reflective adn therefore shows as grey and not shiny. What area are you trying to solder? Why is the temperature so far above the liquidous? (This will make the outgassing problem worse). Reduce the temperature in stages as much as you can, and monitor the effect at each stage to determine the best temperature versus soak time. Alternatively, can you pull a vacuum on the soldering process while the solder is above liquidous? This would help the outgassing of volatiles. Pete Duncan Jonathan A Noquil <Jonathan.A.Noquil@FAIRCHIL To: [log in to unmask] DSEMI.COM> cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group) Sent by: TechNet Subject: [TN] Solder Voiding <[log in to unmask]> 05/11/01 05:55 PM Please respond to "TechNet E-Mail Forum."; Please respond to Jonathan.A.Noquil 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 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------