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Old solder paste: the answer

At this web site

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Kester gives a test for whether solder paste is fresh enough. The test is to melt a drop of it onto an unsolderable surface and see whether it forms one ball or several. If it sheds a number of smaller balls (rather than forming just one), the flux has deteriorated. The failure mode is flux deterioration.

The funny thing is, I have some solder paste that is 10 years old and seems to pass this test. I'm going to repeat the test more rigorously.

Presumably, paste that is too old for surface mount work could still come in handy in larger-scale work. It's still solder, after all.

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mc
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... And it wasn't reproducible. Apparently, a lot of flux had gone to one end of the tube.

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mc

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There ya go then ! So now we all know, and thanks for the update.

Arfa

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Arfa Daily

In article , snipped-for-privacy@ntlworld.com (known to some as Arfa Daily) scribed...

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Indeed. And I'll bet the problem can be suitably addressed by using supplemental flux on the pads before applying the solder paste.

Thanks for digging into this. Good to know.

--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
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Dr. Anton T. Squeegee

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