At this web site

http://www.kester.com/en-us/document...de%20Line).pdf

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.

"mc" wrote in message
...
At this web site

http://www.kester.com/en-us/document...de%20Line).pdf

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.

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

"mc" wrote in message
...

"mc" wrote in message
...
At this web site

http://www.kester.com/en-us/document...de%20Line).pdf

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.

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


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

Arfa

In article ,
(known to some as Arfa Daily) scribed...

snippety

http://www.kester.com/en-us/document...de%20Line).pdf

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.

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


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

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)
http://www.bluefeathertech.com -- kyrrin a/t bluefeathertech d-o=t calm
"Salvadore Dali's computer has surreal ports..."