PMR Write Head Side Shield for Narrowing Write Width
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Solution Overview
Problem
Existing perpendicular magnetic recording (PMR) write head designs fail to effectively balance magnetic field magnitude and gradient in both down-track and cross-track directions, leading to inadequate control over write width and significant adjacent track erasure.
Innovation Solution
A PMR writer structure featuring a narrow write pole section with side shields and a trailing shield, where the side shields are connected to the trailing shield or each other, and have a height limited by the equation SSH≦[(0.6×neck height)+0.08] microns, to minimize fringing fields and prevent adjacent track erasure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full side shield writer structure is used to limit excessive fringe field, then cross-track field gradient is improved, but field magnitude drops below minimal performance requirement
Solution Approach 1:
The patent applies local quality by making the side shields selectively non-contacting only in the region adjacent to the write pole tip where field magnitude is critical, while maintaining shielding function in other regions. This localized differentiation allows the side shields to limit fringe fields without excessively reducing the write field magnitude at the pole tip.
Solution Approach 2:
The side shields are segmented into regions: a first region adjacent to the write pole tip where the shields are spaced apart (non-contacting) to maintain field magnitude, and a second region farther from the pole tip where the shields contact or approach the flared portion to provide fringe field limitation. This segmentation allows different functional zones within the same structure.
2Object-affected harmful factors
If side shields are positioned close to the write pole to narrow write width, then adjacent track erasure is reduced, but field magnitude at the pole tip decreases
Solution Approach 1:
The side shields exhibit local quality by having different spatial relationships to the write pole at different locations: near the pole tip they are spaced apart to preserve field magnitude, while farther away they contact or approach the flared portion to narrow the write width and reduce adjacent track erasure.
Solution Approach 2:
The patent utilizes the down-track dimension (distance from the pole tip along the track) to resolve the contradiction. By varying the side shield position along this dimension rather than maintaining a uniform position, the design achieves both high field magnitude near the pole and narrow write width farther away.
3Measurement precision
If trailing shield is positioned at distance d above the write pole top edge, then down-track gradient is improved, but write field is reduced
Solution Approach 1:
The patent applies partial action by using side shields rather than a complete trailing shield structure. The side shields provide partial fringe field limitation without the excessive write field reduction that would result from a full trailing shield positioned at distance d. This partial shielding approach achieves down-track gradient improvement with minimal impact on write field magnitude.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves a narrow magnetic write width and significantly reduces adjacent and far track erasure by optimizing the side shield height and configuration, enhancing recording density and performance.
Implementation Method 1
Magnetic flux in the write pole layer 10 is generated by coils 6 and passes through the pole tip into a magnetic recording media 4 and then back to the write head by entering the flux return pole 8. The side shields surrounding the narrow write pole section and flared portion confine the magnetic flux to narrow the write field width.
Implementation Method 2
a shield structure comprised of a side shield along each of the opposite sides of the narrow write pole section, and a trailing shield at a certain distance above the top edge... to minimize fringing fields and prevent adjacent track erasure
Data Source
AI summary
A side shield structure for a PMR write head is disclosed that narrows write width and minimizes adjacent track and far track erasure. The side shield structure on each side of the write pole has two sections. One section along the ABS and adjacent to the pole tip has a height (SSH1) defined by SSH1≦[(0.6×neck height)+0.08] microns. There is a non-magnetic gap layer between the first section and a second section that is formed adjacent to the flared sides of the main pole layer and serves to suction leakage flux from the flared portion and prevent unwanted flux from reaching the first side shield sections. A fabrication method is provided that includes electroplating the first side shield sections, depositing the non-magnetic gap layer, and then electroplating the second side shield sections. Subsequently, a main pole layer and a trailing shield are formed.