Jon,

I come back to your recipe for etching Al2O3 and found that CrO3 (chromium
trioxide) is highly toxic and carcinogen. Do you have another recipe that
also works ?

Thanks in advance,

Stefan.
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Dipl.-Ing. Stefan Wiechmann
TU Hamburg-Harburg
Mikrosystemtechnik 4-07
Eissendorfer Str. 42
21073 Hamburg
GERMANY
Tel.: ++49 (0)40 42878 - 2397
Tel.: ++49 (0)40 42878 - 2396

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-- original message
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David,

We use the following to remove Al2O3 from the Al substrate.  You may have to
experiment with the amount of time or some of the weights.  Otherwise this
works very well.  Hope this helps.

6.0  g. phosphoric acid            at 35-40 C.
1.55 g. chromium trioxide
100.0 ml water


Best regards,

Jon Hiller