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Method of Etchant Control During Residual Copper Removal

IP.com Disclosure Number: IPCOM000037806D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Canfield, D: AUTHOR [+5]

Abstract

A photo-resist applied to circuit panels prior to additive plating has been known to break down in the plating process due to high ph and temperature of the plating solution. This permits deposition of residual copper in functional areas on the circuit panel. Such copper deposits are a problem in that they are a potential source of shorts between circuit lines. Such copper deposits cannot be removed using standard etching processes because of the presence of circuit lines which must remain unaffected.

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Method of Etchant Control During Residual Copper Removal

A photo-resist applied to circuit panels prior to additive plating has been known to break down in the plating process due to high ph and temperature of the plating solution. This permits deposition of residual copper in functional areas on the circuit panel. Such copper deposits are a problem in that they are a potential source of shorts between circuit lines. Such copper deposits cannot be removed using standard etching processes because of the presence of circuit lines which must remain unaffected.

These copper deposits which are lower in total height than the circuit lines, however, can be removed by the mild etching process as follows:

Apply an etching process sequence beginning with Rohco Solder Stripper for 3 minutes (Solder Stripper is a trademark of Rohco Corporation.)

The next step in this sequence is to apply a double DI Water Rinse with a duration of 1 minute.

This method, outlined above, actually removes residual seed deposits and cleans the circuit panel for further processing in a multilayer circuit board manufacturing line. The removal of the copper defects also serves as a method for recovery of circuit panels destined for scrap due to residual copper defects and, therefore, leads to higher process yields.

Disclosed anonymously.

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