Suggestion: If you feel so uncomfortable with this long period what you might want to do initially is to pull a sample every 4 weeks or so but only send every third or fourth or whatever for analysis. Then if you do see a big change you can go back and analyse the intermediates to see when it happened. "Expired" samples can be returned to the pot. You can then increase the analysis period until you get a measurable change or to six months or whatever with confidence. Mike Fenner Indium Corporation of Europe T: + 44 1908 580 400 F: + 44 1908 580 411 M: + 44 7810 526 317 W: www.indium.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Graham Collins Sent: Wednesday, July 11, 2001 3:10 PM To: [log in to unmask] Subject: Re: [TN] Wave solder pot analysis Hi Lou We changed to twice a year from monthly. We did this about a year ago, and have not had concerns with it. I guess the big thing you need to feel comfortable is the likelihood of this causing problems. We monitor two solder pots, and the wave solder machine. In the 10 years monitored we've never been over the limits, and there is enough data that I'm comfortable we would see a trend in time. Now, if the use of these pots change dramatically (e.g. if we start tinning a lot of gold leads) then I will worry. So - my recommendation: If you have reasonably stable usage patterns, and good history, then 6 month intervals is fine. If your usage varies dramatically , or you have had instances where it's gone from fine one month to bad the next, then stay with what you are comfortable with. regards Graham Collins Process Engineer, Litton Systems Canada, Atlantic Facility (902) 873-2000 ext 6215 >>> [log in to unmask] 07/11/01 10:54AM >>> TechNetters, I'd appreciate comments on contaminant analysis of a wave solder pot. We had been sending a sample out for analysis (type "C" I think it is, by the mil spec) once per month. Now the solder supplier is telling me that once every six months is more than enough. I've been taking the contaminant data and plotting Q charts (for short-run SPC the modern way, as I've been mentioning in this forum) with the monthly data. What has been your practice and recommendation? At the moment, it is hard for me to feel comfortable with a twice-yearly analysis of what seems to me to be an important material in our manufacturing process. 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 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 ---------------------------------------------------------------------------------