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US4351698A Expired / Lapsed US ⏱️ 0.0 years remaining

Variable sloped etching of thin film heads

Assignee: Unisys Corp
•
Filing: 1981-10-16
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Granted: 1982-09-28
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Expires: 2001-10-16
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Abstract

Abstract A method of fabricating variable sloped, as well as straight, edges on a permalloy body of a thin film head is disclosed. The process comprises forming a titanium layer on the permalloy body covering at least those areas of the body which are intended to exhibit the variable slope. A photoresist layer is formed atop the titanium layer and the permalloy body and is removed in those areas of the titanium layer and permalloy body which are not to be retained as part of the thin film head after etching. The body is then etched with an etchant containing HF and FeCl 3 to form variable sloped edges in those areas of the permalloy body covered with titanium and photoresist and straight edges in those areas of the permalloy body covered only with photoresist.

Inventors

  • 👤 John R. Osborne

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-01 12:40
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/08; C23F1/02; C23F1/04; G; G03; G03F; G03F7/00; G11; G11B; G11B5/00; G11B5/127; G11B5/31; G11B5/3163

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 132 words
A method of fabricating variable sloped, as well as straight, edges on the Ni-Fe body of a thin film head comprising: A. forming a Ti layer on the Ni-Fe body covering at least those areas of the body to exhibit the variable slope; B. forming a photoresist layer atop the Ti layer and Ni-Fe body; c. removing the photoresist in those areas of the Ti layer and Ni-Fe body which are not to be retained as part of the thin film head after etching; D. etching the thin film head with an etchant containing HF and FeCl 3 to form variable sloped edges in those areas of the Ni-Fe body covered with Ti and photoresist and straight edges at the boundary of those areas of the Ni-Fe body covered only with photoresist.
Claim 2
Independent Claim 132 words
A method of fabricating variable sloped, as well as straight, edges on the Ni-Fe body of a thin film head comprising: A. forming a Ti layer on the Ni-Fe body covering at least those areas of the body to exhibit the variable slope; B. forming a photoresist layer atop the Ti layer and Ni-Fe body; c. removing the photoresist in those areas of the Ti layer and Ni-Fe body which are not to be retained as part of the thin film head after etching; D. etching the thin film head with an etchant containing HF and FeCl 3 to form variable sloped edges in those areas of the Ni-Fe body covered with Ti and photoresist and straight edges at the boundary of those areas of the Ni-Fe body covered only with photoresist.
Claim 3
Dependent Claim 13 words
The method of claim 1 wherein the resist is removed after step D.
Claim 4
Dependent Claim 14 words
The method of claim 1 wherein the FeCl 3 etchant also contains ethylene glycol.
Claim 5
Dependent Claim 19 words
The method of claim 1 wherein the straight edges define the pole tip region of the thin film head.
Claim 6
Dependent Claim 20 words
The method of claim 1 wherein the Ti layer is formed to a thickness of approximately 0.8 to 0.1 μm.

References Cited (Backward Citations)

US3210226A Cited
US3666634A Cited
US3808070A Cited
US3968565A Cited
US3833434A Cited
US3839111A Cited
US4224400A Cited
US4022930A Cited
US4092210A Cited
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USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1985-09-27 1986-03-29 1986-09-28 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1989-09-27 1990-03-29 1990-09-28 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1993-09-27 1994-03-29 1994-09-28 $7700.00 Window Closed / Lapsed

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