TechNetters, I've made SPC charts to track tin, copper, gold, and antimony in our wave solder machine. The operator skims dross from the solder pot every morning. We send a solder sample the first of each month to Kester for analysis. Over the past 7 months, there has been a monotonic increase in copper concentration and the past two months have been above the upper control limit. The copper concentration is still well within spec (0.3%, if I am correct, according to the relevant IPC standard) at 0.14%, but I want to make sure we know what is happening. Any comments on these observations? Some years back I had charts for a HASL machine and over perhaps 12 months the semimonthly copper concentration wandered between 0.21 and 0.24 %. Lou Hart --------------------------------------------------------------------------------- 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 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 ---------------------------------------------------------------------------------