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US 6,440,647 B1Granted
Resist stripping process
AssigneeAlpha Metals, Inc.
InventorEric Yakobson
Life of this patent
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Abstract
A process for removing patterned negative working resist from the surface of a substrate during manufacture of printed wiring boards is disclosed. The process includes the steps of contacting the patterned resist with a stripping solution containing an alkalinity source as well as a source of ammonium ions. The stripping solution is characterized in that it does not contain volatile organic compounds (VOCs).
Claims20
A process for removing patterned negative working resist from a copper-clad printed wiring board substrate which comprises the steps of:
- a) providing a copper-clad printed wiring board substrate having a negative working patterned resist on a surface;
- b) providing an aqueous VOC-free resist stripping solution which includes a source of an ammonium ion;
- and
- c) exposing the copper-clad printed wiring board substrate to the stripping solution for a time sufficient to remove all patterned negative working resist from the surface.
1 more element
Dependencies are inferred from the claim text.