Magnetoresistive Writer Element Thermal Expansion for Lapping Alignment

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

During the lapping process of hard disk drive sliders, achieving precise alignment of magnetoresistive writer and reader elements is challenging due to initial disparities in their distances from target values, known as delta distances, which complicates the kiss lapping stage.

Innovation Solution

Applying a controlled current to heat elements in the transducer region to selectively expand the magnetoresistive writer element relative to the reader element, allowing for precise adjustment and alignment by removing the expanded portion during lapping, thereby eliminating or reducing delta distances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional lapping is used without heating, then the lapping process is simple, but the alignment precision of magnetoresistive elements cannot be improved

Engineering Contradiction:

Improvealignment precision of magnetoresistive elementsVSAvoidlapping process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies thermal energy to change the physical state of the magnetoresistive elements by heating them during lapping. This causes thermal expansion of the elements, which modifies their dimensions and enables precise alignment adjustment. The heating parameter is controlled to achieve the desired expansion amount equal to the delta distance, thereby improving alignment precision without overly complicating the process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent directly utilizes thermal expansion of the magnetoresistive elements to solve the alignment problem. By applying controlled heat to specific elements (writer or reader), they expand in the lapping direction by a controlled amount equal to the delta distance, enabling precise positioning relative to each other during the lapping process.

Inventive Principle:

Principle #37Thermal expansion

2Manufacturing precision

If heating is applied to expand magnetoresistive elements, then alignment precision is improved, but energy consumption increases

Engineering Contradiction:

Improvealignment precisionVSAvoidenergy consumption for heating

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies heating locally to specific magnetoresistive elements (either writer or reader elements selectively) rather than heating the entire slider or row bar uniformly. This localized heating approach minimizes energy consumption by directing thermal energy only where needed to achieve the required expansion and alignment, while avoiding unnecessary energy expenditure on other components.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If delta distance between writer and reader elements is large, then manufacturing is easier, but final alignment precision deteriorates

Engineering Contradiction:

Improveinitial manufacturing easeVSAvoidfinal alignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent performs preliminary heating and expansion of the magnetoresistive elements before the final lapping stage. By expanding the elements in advance through controlled heating, the delta distance is reduced prior to lapping, enabling the lapping process to achieve precise final alignment. This preliminary action prepares the elements for accurate positioning without requiring excessive material removal during lapping.

Inventive Principle:

Principle #10Preliminary action

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 method introduces degrees of freedom in the lapping process, enabling precise alignment and planarization of slider elements, improving the accuracy of write pole width and flare angle, especially in perpendicular magnetoresistive heads, by allowing for controlled material removal and precise positioning.

Implementation Method 1

applying a current to an element in the transducer region to generate heat

Methodology Applied

Scientific EffectElectrical resistance heating: Joule Heating

Implementation Method 2

cause at least the first magnetoresistive element to expand in the lapping direction relative to the second magnetoresistive element

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11691242B2Methods of lapping while heating one or more features, and related sliders, row bars, and systems

Publication Date: 2023.07.04 SEAGATE TECH LLC

AI summary

The present disclosure includes methods of lapping that include energizing one or more elements that are located proximal to a first magnetoresistive element in a transducer region and generate heat and cause the first magnetoresistive element to selectively expand in the lapping direction relative to one or more other magnetoresistive elements. The present disclosure also includes methods of lapping that use one or more thermal sensors located proximal to the first magnetoresistive element to help control lapping in the lapping direction. The present disclosure includes related lapping systems and sliders.