Electroplated FeCoNiM Trailing Shield for PMR WATE Reduction
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Solution Overview
Problem
Existing perpendicular magnetic recording (PMR) write heads face challenges with wide adjacent track erasure (WATE) and high bit error rates (BER) due to insufficient damping in the trailing shield, which limits the areal density capability (ADC) of hard disk drives (HDDs).
Innovation Solution
A FeCoNiM composition is formed via electroplating, using Fe2+, Co2+, Ni2+, and a transition metal salt in an aqueous solution, to create a high damping trailing shield with a damping constant >=0.04, minimizing WATE and lowering BER through improved magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional trailing shield materials are used in PMR write heads, then manufacturing is simpler, but wide adjacent track erasure (WATE) occurs and bit error rate (BER) is high
Solution Approach 1:
The patent applies composite materials by developing a multi-layer trailing shield structure comprising a FeCoB alloy layer (providing high damping constant ≥0.04 to reduce WATE and BER), a Ta barrier layer (preventing interdiffusion), and a Ru capping layer (providing structural stability). This composite structure resolves the contradiction by combining materials with complementary properties to achieve both low BER and controlled complexity through systematic material integration.
Solution Approach 2:
The patent applies parameter changes by optimizing the damping constant parameter of the trailing shield material to be ≥0.04 through selective use of FeCoB alloy composition. This parameter optimization directly reduces WATE and BER while maintaining manufacturability, resolving the contradiction by tuning material parameters rather than fundamentally changing the shielding concept.
2Reliability
If high damping material is used in trailing shield, then WATE is reduced and BER is lowered, but electroplating process complexity increases
Solution Approach 1:
The patent applies mechanics substitution by replacing traditional sputtering or physical vapor deposition methods with electroplating technology for depositing the FeCoB alloy layer. This substitution enables precise control of layer thickness and composition through electrochemical parameters, reducing WATE and BER while maintaining manufacturing ease through a well-established electroplating process rather than complex physical vapor deposition equipment.
Solution Approach 2:
The patent applies parameter changes by optimizing electroplating parameters including bath composition (Fe2+, Co2+, B3+ ions), temperature (20-40°C), current density (1-10 mA/cm²), and pH (2-4) to achieve the required damping constant ≥0.04. These parameter optimizations enable precise control of material properties during manufacturing, resolving the contradiction between achieving high performance and maintaining ease of manufacture.
3Reliability
If FeCoNiM composition is electroplated with precise composition control, then magnetic properties are optimized, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by defining specific composition ranges for the FeCoNiM alloy (Fe: 60-70 at%, Co: 10-20 at%, Ni: 5-15 at%, M: 3-10 at% where M is a transition metal) and controlling electroplating parameters (temperature 20-40°C, pH 2-4, current density 1-10 mA/cm²) to achieve optimal magnetic properties. These parameter specifications balance manufacturing precision requirements with performance optimization, making the process controllable with standard manufacturing tolerances.
Solution Approach 2:
The patent applies local quality by introducing a Ta barrier layer (5-20 nm thick) at the interface between the FeCoB trailing shield and the Ru capping layer. This localized interlayer prevents interdiffusion of Fe, Co, and B atoms into the Ru layer, maintaining the local compositional integrity and magnetic properties of each layer while allowing overall composition optimization, thus reducing the precision burden on the bulk material deposition process.
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 high damping trailing shield reduces WATE and BER, enhancing the areal density capability (ADC) of PMR write heads by promoting more trailing return field and improving data storage efficiency.
Implementation Method 1
The FeCoNiM composition can be formed via an electroplating process by adding Fe2+, Co2+, Ni2+ and a transition metal salt to an aqueous solution comprised of other additives in an electroplating cell that has an Ni or Co as the anode
Data Source
AI summary
The present embodiments relate to a PMR write head with a trailing shield that comprises a FeCoNiM composition. The FeCoNiM composition can be formed via an electroplating process by adding Fe2+, Co2+, Ni2+ and a transition metal salt to an aqueous solution comprised of other additives in an electroplating cell that has an Ni or Co as the anode. The plated HD magnetic material as the trailing shield in a PMR writer can minimize a wide area track erasure (WATE). Further, a high moment high damping shield can lower bit error rate (BER) and increase aerial density capability (ADC) of the write head.