Browse Prior Art Database

Renewing Etchant

IP.com Disclosure Number: IPCOM000075524D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Greene, KF: AUTHOR

Abstract

The drawing shows a method and apparatus for renewing an ammonium persulfate solution used for etching printed circuit boards. A tank 2 holds the material to be supplied to an etcher. As the etch operation proceeds, the ammonium persulfate is to be added to tank 2 and water is to be added to make up for evaporation.

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Renewing Etchant

The drawing shows a method and apparatus for renewing an ammonium persulfate solution used for etching printed circuit boards. A tank 2 holds the material to be supplied to an etcher. As the etch operation proceeds, the ammonium persulfate is to be added to tank 2 and water is to be added to make up for evaporation.

A tank 3 has a dividing baffle 4 forming two sections 5 and 6. Section 5 is filled to a predetermined level with ammonium persulfate salts. Saturated solution from section 5 overflows baffle 4 into section 6. A pump 7 circulates the solution from section 6 to section 5.

As the ammonium persulfate is depleted, valve 8 is conventionally controlled to transfer the solution from section 6 to tank 2. When solution is transferred from section 6 to tank 2, tank 2 may overflow to section 5.

Additional ammonium persulfate salt is added to section 5 without weighing or calculation. As salt is added to section 5, the solution overflows baffle 4 to raise the level in section 6. Water is then added to section 6 to raise the level to a starting point. The amount of added water is noted and a related amount of catalyst is added.

Sections 5 and 6 are ordinarily of equal size. Baffle 4 may be made moveable to adjust the relative sizes of sections 5 and 6 for particular applications.

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