Treatment alkali etching

PET (40). Polymers can also be etched by treatment with oxygen plasma (82). Dissolution of alumina templates is easily achieved by immersion in strong alkali such as 5 M KOH or NaOH (20). 

Wedekind f has demonstrated that zirconium sol may be made by etching the metal with hydrochloric acid. A powder is thus obtained that goes into colloidal solution on washing with water. This hydrosol gives very peculiar reactions with electrolytes. Most acids precipitate it, but tartaric and picric acids will not. The hydroxides of the alkali metals precipitate it immediately, but ammonia water does so very slowly. Most neutral electrolytes have little or no effect. It is probable that the treatment with HCl forms a protective colloid which causes the unusual behavior. 

Etching with 0.04 -0.07 M of an oxidant selected from the group comprising O2,03, H2O2, the acid HE, ammonium or alkali metal salts of NO3, 820 , NO , B40 , or CIO, or a mixture thereof. The treated silicon is suitably separated from the solution after the treatment. 

The treatment for fluorocarbon polymers is usually based upon metallic sodium dissolved in a solution of naphthalene in a polar aprotic solvent such as tetrahydrofuran, although other etch treatments such as a solution of alkali metal in liquid ammonia [12] have been reported [13]. Details for the preparation of the treatment solutions have been published [14] and solutions of sodium naphthalenide are commercially available, e.g. under the trade name Tetraetch from W. L. Gore Associates Inc. These commercial pretreatments are relatively easy and safe to operate and widely used in industry. Also, it is possible to purchase fluorocarbon polymers already treated by such chemical processes. 

Specific Surface treatment, deposition of alkali fluoride should be prevented Transmutation of the etching products with etching salts into insoluble silicon fluorides Very aggressive solution and high etching rates... 

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