Browse Prior Art Database

Warning System for GMR products using Read element resistance

IP.com Disclosure Number: IPCOM000014666D
Original Publication Date: 2002-Feb-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 6 page(s) / 154K

Publishing Venue

IBM

Abstract

Damages either physical or chemical at the GMR senor creates risks of amplitude degradation, instability and other functional problems. This can occur during manufacturing process/test and/or high humidity stress environmental conditions. The system will monitor/record the resistance(R) change to diagnose the integrity of the GMR sensor. Initial R can be from any phase of drive's life Fig.1 (i.e. HDE,HSA,HGA level). HSA,HGA component values will be monitored/recorded on external systems( i.e. Server) and from Mfg test on the internal measurement circuit(built in AE,Card) will be used to record any R changes . HSA/HGA data will be stored in the drive during the mfg test.. Examples of it's applications are listed below: 1) Mfg process/test screening, using delta from Slider,HSA (Fig.1) 2) GMR corrosion monitoring: Early warning for sensor degradation (Fig.2)

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Page 1 of 6

Warning System for GMR products using Read element resistance

Damages either physical or chemical at the GMR senor creates risks of amplitude degradation, instability and other functional problems. This can occur during manufacturing process/test and/or high humidity stress environmental conditions. The system will monitor/record the resistance(R) change to diagnose the integrity of the GMR sensor. Initial R can be from any phase of drive's life Fig.1 (i.e. HDE,HSA,HGA level). HSA,HGA component values will be monitored/recorded on external systems( i.e. Server) and from Mfg test on the internal measurement circuit(built in AE,Card) will be used to record any R changes . HSA/HGA data will be stored in the drive during the mfg test..

Examples of it's applications are listed below:
1) Mfg process/test screening, using delta from Slider,HSA (Fig.1)
2) GMR corrosion monitoring: Early warning for sensor degradation (Fig.2)

GMR corrosion monitor. Drive storage in high humidity condition is the most likely stage of the Drive's life to experience humidity stress. Graph 1,2,3 show progressive degradation of the amplitude(Amp) and R. When Amp values degrades below a critical level the drive is unable to read data from the media and irreversible, but as shown in Graph 1 Amp measurement fluctuates w/o any stress and has a large error bar( Graph 4) which may include media degradation, flyheight change etc.. Therefore not Amp measurement is not reliable source to monitor degradation. Using R delta we are able to measure sensor degradation more accurately and detect it in time to send out an early warning ( i.e. delta R > 3ohm), other advantage is that head does not have to fly over the media for the R measurement.

The R change is the most accurate and simple/direct measure of GMR sensor damage, corrosion during mfg process and
drive life's

Fig. 1 Mfg screening example

1

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MFG SCREENING Example

HGA

MONITOR/RECORD DELTA

MONITOR/RECORD DELTA

MONITOR/RECORD DELTA

MONITOR/RECORD DELTA

MONITOR/RECOR...