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Quasi Static Testing Ultimate Solution for Cost Effective Quality Verification and ESD Analysis of GMR Heads Henry Patland Wade Ogle 2192 Bering Drive.

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Presentation on theme: "Quasi Static Testing Ultimate Solution for Cost Effective Quality Verification and ESD Analysis of GMR Heads Henry Patland Wade Ogle 2192 Bering Drive."— Presentation transcript:

1 Quasi Static Testing Ultimate Solution for Cost Effective Quality Verification and ESD Analysis of GMR Heads Henry Patland Wade Ogle 2192 Bering Drive San Jose, CA 95131 hpatland@isiguys.com www.isiguys.com

2 Welcome to Complex World of GMR Head

3 Manufacturing GMR heads with good Yield, Reliability and Cost GMR is a new complex technology requiring new manufacturing and test methodology GMR technology provides huge advances in Arial Density GMR is the most ESD sensitive mass produced device in the world Is There an ultimate test solution for manufacturing GMR heads with good Yield, Reliability and Cost?

4 WAFER (Semiconductor Process, Test) ROW/BAR (Wafer Slicing, Row Level Lapping, Test) SLIDER (Row Dicing, Slider Level Lapping, Test) HGA (Assy from Sliders, Suspension, FCBAs, Test) HSA (Assy from HGAs, Actuator, VC, FCBAs, Preamp Chip, Test) HDA (Assy from HSAs, Media, Enclosures, Drive PCB, Servo,Test) How many places in your manufacturing process can GMR elements get damaged? GMR Manufacturing Process

5 Basics of Quasi-Static Testing The roots of QST are derived from actual drive operation As GMR passes over a disk it is introduced to a variety of magnetic field. In simplest terms the resistance of the GMR is dependent on the magnetic field applied to it. In ideal case the relationship of GMR resistance to applied field is linear, but we dont live in ideal world. Close To Ideal Transfer Curve

6 QST Testing as a Concept Independent of external influence (disk variation) Significantly more flexible, with the ability to subject the GMR to any variety of operating conditions. Can analyze pure GMR performance with higher resolution than DET Testing. Reduced Risk of Handling or Tester damaging heads QST Testing is inexpensive, fast, relatively simple, and requires significantly lower maintenance and operating costs compared to DET Testing. Quasi Static Testing can characterize the GMR performance, with the following advantages over DET Testing:

7 QST Transfer Curve Resistance Amplitude Asymmetry Barkh Jump Hysteresis Bias Point Delta R/R Bias Angle Slope Max Slope Parametrics extracted from QST Transfer Curve

8 Common Anomalies which cause errors in a drive Amplitude variation Asymmetry Baseline anomalies Single Bit Jumps (Kinks)

9 Can QST screen out these Anomalies? Amplitude / Asymmetry Variation Baseline Shift / Popping Field Induced Instabilities (Kinks) Reader Induced Instabilities Writer Induced Instabilities ESD Soft/Hard Damage (Amplitude, Pin -Reversal, Asymmetry) DET/Drive Correlation

10 Amplitude/Asymmetry Variation Poor Amplitude High Asymmetry

11 Base Line Shift / Popping Large Hysteresis Barkhausen Jump

12 Field Induced Instabilities Kink / Max Slope Field Instability at 40 Oe

13 Reader Induced Instabilities Reader Instability

14 Writer Induced Instabilities (Popcorn)

15 ESD Soft / Hard Damage Amplitude and Asymmetry Degradation Pin-Layer Reversal No Amplitude – Hard Damage

16 Drive Anomaly Correlation Amplitude variation in Drive caused by High Hysteresis shown in Transfer Curve

17 QST to DET Correlation Test conditions QST-2002 Sweep: 275 Oe Measured at 250 Oe Bias Current: 5 mA Guzik 1001 + 1701 Frequency: 5 MHz Filter:60 MHz Bias Current: 5 mA RPM:5400

18 The Answer is YES, QST can screen out most common Anomalies! Drive AnomalyQST Function Amplitude/Asymmetry VariationTransfer Curve Amplitude/Asymmetry Baseline Shift / PoppingTransfer Curve Barkhausen Jump and Hysteresis Field Induced Instabilities (Kinks)Transfer Curve Max Slope and Field Induced Noise Test Writer/Reader Induced InstabilitiesWriter/Reader Induced Noise Test ESD Damage (Amp, Pin-Reversal, Asymmetry) Transfer Curve Amp, Asymmetry and Slope DET/ Drive CorrelationYES

19 Additional Functionality of QST Testers Static Tests of HSA components including Preamp Chip, Voice Coil, FCBA, Writer Elevated Temperature Testing PZT Suspension Testing ESD Failure Threshold Testing

20 ESD Damage to GMR heads is considered one of the worst problems in Manufacturing Today Due to sensitivity to ESD, GMR heads can be easily damaged or destroyed by the slightest ESD event caused by Humans or Machines in Manufacturing Unfortunately, this problem is here to stay and will only get worse in near future as the ESD Failure Voltage level is inversely proportional to Arial Density CDM (Charged Device Model) is rapidly becoming the standard for characterizing GMR head ESD Failure Thresholds

21 QST can characterize ESD damage by applying a controlled ESD events to GMR head HBM: 10% Resistance Change Sensor Damage CDM: 100% Resistance Change Multiple distributed melting points

22 What can be done about GMR head ESD Sensitivity ? Improved design of GMR head which is less sensitive to ESD Eliminate ESD events from Manufacturing Monitor GMR head performance after every significant process to isolate and eliminate ESD events in Manufacturing As Al Wallash – Maxtor would put it: Dont loose your head over ESD Whatever you do, QST Testing can Help!

23 By Applying Varying Amplitude ESD Events to GMR Head, QST can easily determine heads Failure points Amp Failure Pin Reversal Resistance Failure Meltdown Asymmetry Failure

24 Direct-CDM Sweep CDM Failure Threshold at 5V Partial Damage

25 QST is the Ultimate Test Solution for GMR head manufacturing QST Testing Methodology can be applied from Wafer to HDA level testing QST Testing can screen out bad heads early in manufacturing process QST Testing can identify which processes in Manufacturing are ESDing your heads QST Testing is fast and inexpensive QST Testing can be done with None or Very Little Handling on many test levels QST surpasses DET in analyzing pure GMR performance

26 References [1] J.Himle, R.Cross, M.Greenwell, Drive-Level Instabilities Correlated to Quasi- Static Field Testing, MMM-Intermag 2001 [2] C. Moore, A Comparison of Quasi-Static Characteristics and Failure Signatures of GMR Heads subjected to CDM and HBM ESD Events [3] Integral Solutions Intl, Quasi 97 and QST-2002 Tester

27 Acknowledgements Al Wallash – Quantum/Maxtor Mark Nichols – Quantum/Maxtor Jenny Himle - Maxtor


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