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Flux turns BRIGHT yellow when in contact with Tin/ Lead

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#84722

Flux turns BRIGHT yellow when in contact with Tin/ Lead | 1 April, 2020

We are using Superior 515 flux to clean and tin selective solder nozzles. Yesterday the flux turned a bright yellow (like a highlighter) when heated after the flux being applied. This does not happen with our Lead Free solder, only the Lead alloy. We even applied some flux to a bar of solder and heated it up, again the LEAD turned yellow and the RoHS did not.

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#84723

Flux turns BRIGHT yellow when in contact with Tin/ Lead | 1 April, 2020

The brush also turned yellow.

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#84724

Flux turns BRIGHT yellow when in contact with Tin/ Lead | 1 April, 2020

Very interesting.Safety datasheet suggest acid that might turn yellowish. I am interested is it cleaned easily with water?

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#84725

Flux turns BRIGHT yellow when in contact with Tin/ Lead | 1 April, 2020

We did not try using water. Once the nozzles were left in the pot a while longer, the yellow goes away. Suggesting that it's cooking off.

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#84729

Flux turns BRIGHT yellow when in contact with Tin/ Lead | 1 April, 2020

And this is why you see it only in Leaded process I guess.

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#84733

Flux turns BRIGHT yellow when in contact with Tin/ Lead | 2 April, 2020

If you can find some, you might want to give Adipic Acid a try. It is a powder but I have seen it work well.

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