Kathy,

The answer is not to eliminate tin oxide. It is to prevent it. Once the oxide is formed, in
excessive amounts, it is difficult if not impossible to perform soldering operations, of any type,
to effect acceptable solder joints. When the oxide is present, no type atmosphere removes it. Your
flux didn't. Nitrogen won't as it only prevents.

Your oxide analysis should include SEM/EDX. Objectively, this will show type and amount present.
When excessive, cause is found and eliminated to prevent further occurrences.

To prevent it is not always easy either. This especially is true when the tin coating process is not
effectively managed (sometimes difficult) or post coating handling and storage requirements are not
met (less difficult). Most tin coatings oxidize readily and rapidly. A newer type (white) is said
not to do so, though I've not had the opportunity to see evidence.

Enjoy,

Earl Moon

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