Composite Thin Film Magnetic Head Parasitic Capacitance Reduction

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Solution Overview

Problem

The miniaturization of hard disk drive components leads to increased crosstalk between writing and reading sides in magnetic heads, causing degradation in read head characteristics due to higher current density, heat dispersion issues, and voltage changes, which existing technologies fail to adequately address.

Innovation Solution

A composite type thin-film magnetic head with a CPP structure is designed, featuring a MR read head element with upper and lower shield layers and an inductive write head element, where parasitic capacitance between the write coil and upper shield layer is set to 0.1 pF or less, and compensating capacitors are used to equalize parasitic capacitances, reducing crosstalk voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the magnetic head is miniaturized to increase recording density and reduce HGA size, then the hard disk drive can be downsized and recording capacity increased, but crosstalk between writing and reading sides increases due to higher current density and decreased heat dispersion

Engineering Contradiction:

ImproveHGA sizeVSAvoidcrosstalk

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an insulating layer as an intermediary between the write coil and the upper shield layer. This insulating layer acts as a mediator that reduces parasitic capacitance C12, thereby reducing crosstalk voltage from the write head to the read head while allowing the miniaturized structure to maintain its compact size

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical parameter of parasitic capacitance C12 by controlling the thickness and material of the insulating layer. By adjusting these parameters, the capacitance is reduced to minimize crosstalk while maintaining the miniaturized structure's electrical characteristics

Inventive Principle:

Principle #35Parameter changes

2Productivity

If higher frequency writing is used to increase recording speed, then productivity improves, but voltage changes cause crosstalk that degrades read head characteristics

Engineering Contradiction:

Improverecording speedVSAvoidread head characteristics

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The insulating layer serves as a mediator that isolates the high-frequency voltage changes from the read head, allowing high-speed recording while protecting read characteristics from crosstalk-induced degradation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The insulating layer is introduced beforehand to prevent crosstalk before it can affect the read head. By proactively reducing parasitic capacitance, the system is cushioned against the harmful effects of high-frequency writing-induced voltage changes

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Length of moving object

If the cross section area of the magnetic head element is decreased to miniaturize, then the head size is reduced, but current density increases and heat dispersion decreases

Engineering Contradiction:

Improveelement cross section areaVSAvoidheat dispersion

Core Design Contradiction:

Length of moving objectVSTemperature

Solution Approach 1:

The insulating layer acts as a thermal intermediary that helps manage heat dispersion in the miniaturized structure. By introducing this layer, the thermal pathways are modified to improve heat dissipation from the high current density regions while maintaining the reduced cross-section area

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

This configuration significantly reduces crosstalk voltage, preventing degradation of read head performance, extending the operating life of read head elements, and maintaining magnetic properties by minimizing electrical resistance changes and electromigration effects.

Implementation Method 1

a capacitance C12 between the write coil and the upper shield layer, set to 0.1 pF or less

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

an inductive write head element formed on the MR read head element, having an upper magnetic pole layer, a recording gap layer, a lower magnetic pole layer whose end portion is opposed to an end portion of the upper magnetic pole layer through the recording gap layer, and a write coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS7274539B2Composite type thin film magnetic head having a low parasitic capacitance between a write coil and an upper read head shield

Publication Date: 2007.09.25 TDK CORP

AI summary

A composite type thin-film magnetic head is provided, which comprises: a MR read head element having an upper shield layer, a lower shield layer, an MR layer in which a sense current flows in a direction perpendicular to a surface of the layer through the upper shield layer and the lower shield layer; an inductive write head element formed on the MR read head element, having an upper magnetic pole layer, a recording gap layer, a lower magnetic pole layer where end portion is opposed to an end portion of the upper magnetic pole layer through the recording gap layer, and a write coil; and a capacitance C12 between the write coil and the upper shield layer, set to 0.1 pF or less.