Tunnel Magnetoresistive Element Testing via Resistance Change Ratio

Solution Overview

Problem

Existing methods for testing tunnel magnetoresistive (TMR) elements are time-consuming and labor-intensive, requiring extensive manpower and time to confirm their reliability without damaging the elements, which is not suitable for mass production.

Innovation Solution

A method involving the measurement of resistances using multiple sense currents with different current values, calculating the ratio of change in resistance, and evaluating the TMR elements based on this ratio to quickly and easily determine their reliability without causing damage, allowing for 100% inspection of manufactured TMR elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electromagnetic conversion performance test is performed to confirm reliability of TMR element, then reliability confirmation is achieved, but testing time and labor cost increase significantly

Engineering Contradiction:

Improvereliability confirmationVSAvoidtesting time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts the essential reliability indicator from complex electromagnetic conversion performance tests. By measuring only the resistance change ratio of the TMR element, the method isolates the key parameter that correlates with reliability while eliminating unnecessary test complexity, thus reducing testing time and labor cost while maintaining reliability assessment capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a simplified test model that copies only the essential measurement aspect of the original complex test. Instead of performing full electromagnetic conversion performance tests, the invention uses a copied measurement approach - measuring resistance at different current levels and calculating the ratio - which preserves the reliability assessment function while dramatically reducing test time and resource requirements

Inventive Principle:

Principle #26Copying

2Reliability

If electromagnetic conversion performance test is performed to confirm reliability of TMR element, then reliability confirmation is achieved, but labor cost increases significantly

Engineering Contradiction:

Improvereliability confirmationVSAvoidlabor cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts the essential reliability indicator from complex electromagnetic conversion performance tests. By measuring only the resistance change ratio of the TMR element, the method isolates the key parameter that correlates with reliability while eliminating unnecessary test complexity, thus reducing testing time and labor cost while maintaining reliability assessment capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a simplified test model that copies only the essential measurement aspect of the original complex test. Instead of performing full electromagnetic conversion performance tests, the invention uses a copied measurement approach - measuring resistance at different current levels and calculating the ratio - which preserves the reliability assessment function while dramatically reducing test time and resource requirements

Inventive Principle:

Principle #26Copying

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 approach enables rapid and efficient evaluation of TMR elements, ensuring their reliability without destruction, thereby facilitating effective mass production by distinguishing non-defective from defective products through the calculated resistance change ratio.

Implementation Method 1

testing a tunnel magnetoresistive effect (TMR) element such as a TMR read head element using the tunnel magnetoresistive effect

Methodology Applied

Scientific EffectTunnel magnetoresistive effect: Magnetoresistance

Data Source

PatentUS7417442B2Method and apparatus for testing tunnel magnetoresistive effect element, manufacturing method of tunnel magnetoresistive effect element and tunnel magnetoresistive effect element

Publication Date: 2008.08.26 TDK CORP

AI summary

A method for testing a TMR element includes a step of measuring a plurality of resistances of the TMR element by feeding a plurality of sense currents with different current values each other through the TMR element, a step of calculating a ratio of change in resistance from the measured plurality of resistances of the TMR element, and a step of evaluating the TMR element using the calculated ratio of change in resistance.