Cleaning instructions for Iron Oxide Photomasks
THE BEST PROCESS FOR CLEANING IRON OXIDE PHOTOMASKS FOLLOWS:
1. Dip masks in a solution of Sodium Dichromate and Sulfuric Acid* for 3 to 5 seconds at a bath temperature of 21° C.
2. Rinse immediately with running water.
3. Using a soft cotton swab, wash in Photo-Flo 600** solution.
4. Rinse in De-Ionized and filtered water.
5. Air dry in clean atmosphere.
* The Sodium Dichromate and Sulfuric Acid bath is composed of 35 milliliters of super-saturated Sodium Dichromate to one liter of Sulfuric Acid. Add the Sodium Dichromate solution to the Sulfuric Acid and cool to 21º C
** Photo-Flo 600 is a product of Eastman Kodak Co., Rochester, NY, USA. Use one part Photo-Flo 600 to 600 parts water.
If the use of Sodium Dichromate and Sulfuric Acid bath is a problem, you may substitute photoresist stripper for 30 to 60 seconds in step 1, and hot running water in step 2. This alternative method works well, but not quite as well as the preferred method.