Antistatic Layer Design for Thin-Film Magnetic Head Noise Suppression

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional thin-film magnetic heads experience noise issues due to voltage potential differences caused by electrostatic charges between the read head elements and the protective coat, particularly in TMR and CPP-GMR effect elements, which are difficult to resolve with existing antistatic measures.

Innovation Solution

A thin-film magnetic head design incorporating an antistatic means with a lower resistivity than the substrate, partially covered by the protective coat, to facilitate charge movement and eliminate voltage potential differences, connected to ground and strategically positioned adjacent to the read head element to suppress noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a protective coat made of insulating film is formed on the head end surface to cover the end surfaces of electrode layers and TMR effect multilayer, then the end surfaces are protected from wearing with the magnetic disk, but electrostatic charge accumulates on the protective coat causing noise in read signals

Engineering Contradiction:

Improveprotection of end surfacesVSAvoidelectrostatic charge and noise

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

A ground structure is introduced as an intermediary element between the protective coat and the TMR effect element. This ground structure provides a charge dissipation path that prevents electrostatic charge accumulation on the protective coat, thereby eliminating the harmful noise effect while preserving the protective function of the insulating film coating.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a ground structure is formed to prevent electrostatic discharge, then discharge is prevented, but noise may still occur due to capacitor formed between protective coat surface and end surfaces

Engineering Contradiction:

Improveprevention of dischargeVSAvoidnoise from capacitor

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The ground structure serves as an intermediary charge dissipation path that connects the protective coat to ground potential. This eliminates the capacitor effect between the protective coat and TMR element by providing a continuous charge release mechanism, thereby preventing both discharge and noise generation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If ion milling process is used to create TMR effect element, then high precision structure is achieved, but electrostatic charge is generated on the TMR effect element

Engineering Contradiction:

Improvestructure precisionVSAvoidelectrostatic charge

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The ground structure acts as an intermediary charge dissipation mechanism that is integrated into the head structure. It provides a continuous path for charge release during and after the ion milling process, preventing electrostatic charge accumulation on the TMR effect element while preserving the manufacturing precision achieved through ion milling.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If contact between magnetoresistive effect element and magnetic disk is allowed, then data reading is achieved, but electrostatic charge is generated causing damage or breakdown of the MR effect element

Engineering Contradiction:

Improvedata reading functionVSAvoiddamage or breakdown of MR effect element

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The ground structure serves as a protective intermediary that provides charge dissipation during the contact period between the magnetoresistive element and magnetic disk. This prevents electrostatic charge accumulation that would otherwise cause damage or breakdown, while allowing the necessary contact for data reading to occur.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively suppresses electric noise by allowing charge movement between the protective coat and the antistatic layer, reducing voltage potential differences and improving read head performance.

Implementation Method 1

at least one antistatic means for preventing the protective coat from being electrostatically charged, formed on/above the element formation surface, one end surface of the at least one antistatic means reaching the head end surface

Methodology Applied

Scientific EffectElectrostatic charge dissipation: Electrostatic Discharge

Data Source

PatentUS7864489B2Thin-film magnetic head having an antistatic layer preventing a protective coat from being electrostatically charged

Publication Date: 2011.01.04 TDK CORP

AI summary

Provided is a thin-film magnetic head in which a noise due to the voltage potential difference between the read head element and the protective coat surface is suppressed. The thin-film magnetic head comprises: a read head element, one end surface of the read head element reaching an head end surface on the ABS side; a protective coat formed on the head end surface in such a way to cover at least the one end surface of the read head element; and at least one antistatic means for preventing the protective coat from being electrostatically charged, formed on/above the element formation surface, one end surface of the at least one antistatic means reaching the head end surface, the protective coat covering a portion, not the whole, of the one end surface of the at least one antistatic means on the head end surface.