Wensen Li
Engineering at Leslie St, Fremont, CA
License number
Louisiana EI.0017329
Issued Date
Sep 24, 1996
Category
Civil Engineer
Address
Address
39634 Leslie St APT 142, Fremont, CA 94538
Professional information
Etching Process To Selectively Remove Copper Plating Seed Layer
US Patent:
6767477, Jul 27, 2004
Filed:
Jun 12, 2002
Appl. No.:
10/170106
Inventors:
Xue Hua Wu - Union City CA
Wensen Li - Fremont CA
Si-Tuan Lam - San Jose CA
Henry C. Chang - San Jose CA
Kochan Ju - Fremont CA
Wensen Li - Fremont CA
Si-Tuan Lam - San Jose CA
Henry C. Chang - San Jose CA
Kochan Ju - Fremont CA
Assignee:
Headway Technologies, Inc. - Milpitas CA
International Classification:
C23F 100
US Classification:
216105, 216 22, 252 791, 252 795
Abstract:
Write head coils for magnetic disk systems are commonly formed through electroplating onto a seed layer in the presence of a photoresist mask. It is then necessary to remove the seed layer everywhere except under the coil itself. The present invention achieves this through etching in a solution of ammonium persulfate to which has been added the complexing agent 1,4,8,11 tetraazundecane. This suppresses the reduction of Cu to Cu, thereby increasing the dissolution rate of copper while decreasing that of nickel-iron. Two ways of implementing this are describedâadding the complexing agent directly to the ammonium persulfate and introducing the 1,4,8,11 tetraazundecane through a dipping process that precedes conventional etching in the ammonium persulfate.
Etching Process To Selectively Remove Copper Plating Seed Layer
US Patent:
6428719, Aug 6, 2002
Filed:
Jan 19, 2000
Appl. No.:
09/487454
Inventors:
Xuehua Wu - Union City CA
Wensen Li - Fremont CA
Si-Tuan Lam - San Jose CA
Henry C. Chang - San Jose CA
Kochan Ju - Fremont CA
Wensen Li - Fremont CA
Si-Tuan Lam - San Jose CA
Henry C. Chang - San Jose CA
Kochan Ju - Fremont CA
Assignee:
Headway Technologies, Inc. - Milpitas CA
International Classification:
C23F 100
US Classification:
216105, 216 22
Abstract:
Write head coils for magnetic disk systems are commonly formed through electroplating onto a seed layer in the presence of a photoresist mask. It is then necessary to remove the seed layer everywhere except under the coil itself. The present invention achieves this through etching in a solution of ammonium persulfate to which has been added the complexing agent 1,4,8,11 tetraazundecane. This suppresses the reduction of Cu to Cu, thereby increasing the dissolution rate of copper while decreasing that of nickel-iron. Two ways of implementing this are describedâadding the complexing agent directly to the ammonium persulfate and introducing the 1,4,8,11 tetraazundecane through a dipping process that precedes conventional etching in the ammonium persulfate.