Magnetic thin film head, the fabrication method, and magnetic disk

Abstract

In formation of an upper shield of a magnetic thin film head by electroplating, a current density of electroplating is regulated stepwise with time. Thus, in the upper shield formation, a film composition and magnetic characteristic with respect to the direction of film thickness can be controlled precisely, making it possible to provide a magnetic thin film head featuring significantly reduced noise-after-write and output fluctuation.

What is claimed is:  
     
         1 . A magnetic thin film head comprising: 
 a write head element; and    a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein Ni in composition of a formed layer is 80.8 wt % to 82.0 wt %.    
     
     
         2 . A magnetic thin film head according to    claim 1   , in which said Ni is composed of an initially formed layer having a thickness of 1.0 μm is 80.8 to 82.0 wt %, and of an upper layer on said initially formed layer 1.0 μm thick is 81.0 to 81.2 wt %.  
     
     
         3 . A magnetic thin film head comprising: 
 a write head element; and    a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein a magnetostriction constant λ representing a magnetic characteristic of said ferromagnetic film is −2.0 to −7.0×1 −7  in an initially formed layer having a thickness of 1.0 μm, and    wherein said magnetostriction constant λ is −3.0 to −4.0×10 −7  in an upper layer on said initially formed layer 1.0 μm thick.    
     
     
         4 . A magnetic thin film head comprising: 
 a write head element; and    a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein a film thickness exceeding 1.0 μm in said ferromagnetic film formed of NiFe permalloy material has an Ni content accuracy of ±0.1 wt %, and    wherein a film thickness of 1.0 μm or less in said ferromagnetic film formed of NiFe permalloy material has an Ni content accuracy of ±0.3 wt %.    
     
     
         5 . A method of fabricating a magnetic thin film comprising the step of: 
 (a) forming a write head element;    (b) forming a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein Ni in composition of an initially formed layer having a thickness of 1.0 μm is 80.8 to 82.0 wt %, and    wherein Ni in composition of an upper layer on said initially formed layer 1.0 μm thick is 81.0 to 81.2 wt %,    (c) timewise regulating a current density of permalloy electroplating under control of a personal computer;    wherein a plurality of time periods and a plurality of current values are preset for film formation.    
     
     
         6 . A method of fabricating a magnetic thin film comprising the step of: 
 (a) forming a write head element; and    (b) forming a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein a magnetostriction constant λ representing a magnetic characteristic of said ferromagnetic film is −2.0 to −7.0×10 −7  in an initially formed layer having a thickness of 1.0 μm, and    wherein said magnetostriction constant λ is −3.0 to −4.0×10 −7  in an upper layer on said initially formed layer 1.0 μm thick,    (c) timewise regulating a current density of permalloy electroplating under control of a personal computer;    wherein a plurality of time periods and a plurality of current values are preset for film formation.    
     
     
         7 . A method of fabricating a magnetic thin film comprising the step of: 
 (a) forming a write head element; and    (b) forming a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein a film thickness exceeding 1.0 μm in said ferromagnetic film formed of NiFe permalloy material has an Ni content accuracy of ±0.1 wt %, and    wherein a film thickness of 1.0 μm or less in said ferromagnetic film formed of NiFe permalloy material has an Ni content accuracy of ±0.3 wt %,    (c) timewise regulating a current density of permalloy electroplating under control of a personal computer;    wherein a plurality of time periods and a plurality of current values are preset for film formation.    
     
     
         8 . A magnetic disk apparatus having a magnetic thin film head comprising: 
 a write head element; and    a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein Ni in composition of an initially formed layer having a thickness of 1.0 μm is 80.8 to 82.0 wt %, and    wherein Ni in composition of an upper layer on said initially formed layer 1.0 μm thick is 81.0 to 81.2 wt %.    
     
     
         9 . A magnetic disk apparatus having a magnetic thin film head comprising: 
 a write head element; and    a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein a magnetostriction constant λ representing a magnetic characteristic of said ferromagnetic film is −2.0 to −7.0×10 −7  in an initially formed layer having a thickness of 1.0 μm, and    wherein said magnetostriction constant λ is −3.0 to −4.0×10 −7  in an upper layer on said initially formed layer 1.0 μm thick.    
     
     
         10 . A magnetic disk apparatus having a magnetic thin film head comprising: 
 A magnetic thin film head comprising:    a write head element; and    a read head element;    wherein a ferromagnetic film having a soft magnetic characteristic and a magnetic shield function is formed of NiFe permalloy material by electroplating in the vicinity of a sensor film arranged as said read head element,    wherein a film thickness exceeding 1.0 μm in said ferromagnetic film formed of NiFe permalloy material has an Ni content accuracy of ±0.1 wt %, and    wherein a film thickness of 1.0 μm or less in said ferromagnetic film formed of NiFe permalloy material has an Ni content accuracy of ±0.3 wt %.