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Reply To: | TechNet E-Mail Forum. |
Date: | Wed, 6 Dec 2000 15:03:13 -0500 |
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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
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