Quasi Static Testing
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Transcript of Quasi Static Testing
Quasi Static Testing Advanced Quasi-Static Testing Technology and Applications
Henry Patland
2192 Bering DriveSan Jose, CA [email protected]
www.us-isi.com
Topics
Introduction to Quasi-Static Testing
Advanced Quasi-Static Testing Technology
Quasi-Static Testing Applications
QST Testing as a Concept
Independent of external influence (disk/flying height variation)
Significantly more flexible, with the ability to subject the GMR/TMR to any variety of ambient conditions.
Can analyze pure GMR/TMR 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.
Quasi Static Testing can characterize the GMR/TMR performance, with the following advantages over DET Testing:
Basics of Quasi-Static TestingThe roots of QST are derived from actual drive operation
As GMR/TMR passes over a disk it is introduced to a variety of magnetic field.
In simplest terms the resistance of the GMR/TMR is dependent on the magnetic field applied to it.
In ideal case the relationship of GMR/TMR resistance to applied field is linear, but we don’t live in ideal world.
Close To Ideal Transfer Curve
Transverse Transfer CurveResistance
Amplitude
Asymmetry
Barkh Jump
Hysteresis
Bias Point
Delta R/R
Bias Angle
Slope
Max Slope
Parametrics extracted from QST Transfer Curve
DC MeasurementsMeasures head resistance change versus an externally applied magnetic field through a low frequency channel. The following DC tests can be performed.
Transfer curve Stability Bias angle Asymmetry sweep Resistance delta Quasi-Static test
Static Tests (HSA / HDA)Verification of the Preamp Chip, Flex, and Voice Coil assembly can be performed.
Voice coil measurements Fault detection Current consumption Pin-Pin and Pin-Ground shorts Temperature Sensor control Passive component measurements RDX / RDY offset voltage
AC MeasurementsMeasures high frequency noise as influenced by write excitation, field excitation, or combinations of both. The following AC tests can be performed
Popcorn Noise W/R Recovery Field Induced Noise Characterization Frequency Response
AC Channel Technology
Glitch After Write (Popcorn) Field Induced Instabilities (Noise) Spectral Analysis (FFT) 200 Mhz Analog Bandwidth 160 Mhz 10-bit digitizer Low Noise W/R Recovery < 500 ns 400 Mhz Write Frequency
Write Induced InstabilitiesWriter Induced Instabilities
(Popcorn)
Field Induced InstabilitySoft Kink at 160 Oe
Field Induced Instability @ 150 Oe
Field Induced Instability @160 Oe
Field Induced Instability @ 170 Oe
Spectral Maximum Amplitude Noise
Noise RMS (uV)
Noise Amp (uV)
Max Noise Amp (uV)
S.M.A.N
Digitizer is The Key to S.M.A.N.
Qualifies Three Types of Instability Events in One Shot
RMS Noise for broadband noise Max Amp for rare events such as Barkh.
Jumps and Write Induced Instability Amp Noise for high probability noise
Transfer Curve & S.M.A.N.Soft Kink and Max Noise at
160 Oe
Applications for QST Testing
Bar, Slider Testing HGA, HSA, HDA Testing ESD Tolerance Testing Thermal Reliability Testing
Row/Slider Level Testing
Benefits of Row/Slider Testing
Early look at Wafer process for QST Parametrics and Instability
Upstream testing reduces scrap cost Bar to 4000 Sliders/Hour Slider to 1200 Sliders/Hour
HGA, HSA, HDA Level Testing
Benefits of HGA, HSA, HDA Testing
Process Control Simple Test/Tooling Failure Analysis at HDA level HSA Screening Prior to Drive Build HDA Screening After Servo Write
ESD Tolerance Measurement And Process Mapping
ESD Tolerance: Repetitive “Inject and Test” HBM, MM and DCDM
CDM (Charged Device Model) is rapidly becoming the standard for characterizing GMR/TMR head ESD Failure Thresholds
Process Mapping: Test After Each Process Including Bar, Slider, HGA (Before/After DET), HSA Prior to Final Bond and HDA After Merge and After Servo Write
Symptoms: First Failure Mode: Instability, then Parametrics
D-CDM Cartridge Assembly
ESD/CDM Pulse System
CDM Tolerance Characterization
QST can characterize ESD damage by applying controlled ESD events to GMR head
CDM: 100% Resistance Change
Multiple distributed melting points
HBM: 10% Resistance Change
Sensor Damage
What can be done about GMR/TMR head ESD Sensitivity ?
Improved design of GMR/TMR head which is less sensitive to ESD
Eliminate ESD events from Manufacturing Monitor GMR/TMR head performance after every
significant process to isolate and eliminate ESD events in Manufacturing
As Al Wallash – Maxtor would put it:
“Don’t loose your head over ESD”
Whatever you do, QST Testing can Help!
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
DCDM Sweep
50010001500
40
50
60
0.5
1.0
40
50
60
80
100
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
E SD P ro file C u rveB ia s : 5 .0 P a r t ID : H e a d : F a rH d 0
Amp
At T
est (
µV)A
VGR
es
ista
nc
e (
Oh
ms
)AV
GP
opco
rnA
VG
Noi
se A
mp
(µV)
MAX
Ma
x N
ois
e A
mp
(µ
V)M
AX
E P S -DCDM E S D (V )
P OS NE G
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
-150 -100 -50 0 50 100 150
Transverse Transfer C u rveB ia s : 5 .0 P a r t ID : P a r tID H e a d : F a rH d 0
Am
plit
ud
e (
uV
)
M agnetic F ield (O e)
Reverse
-1000
-750
-500
-250
0
250
500
750
1000
0.0 2.5 5.0 7.5 10.0 12.5 15.0
P o pco rn P u lsesS ub T itle
Am
plit
ud
e (
uV
)
Tim e (uS )
519-1 520-1 523-3 524-2 525-2 526-1 527-1
528-4 530-2 531-1 532-3 533-4 534-4 535-6
25
50
75
100
125
150
175
-150 -100 -50 0 50 100 150
Spectral M axim u m Am plitu de N o ise P lo tP a r t ID : P a r tID H e a d : 0
No
ise
Am
plit
ud
e (
µV
)
F ield (Oe)
Noise A m p M ax Noise A m p
CDM Failure Threshold at 3.5V 25% lower than Amp
Failure at 5V
Thermal Reliability Testing
Accelerated Life Testing at Row Level
Accelerated Life Testing at HGA Level
Accelerated Life Testing at Row Level
Accelerated Life Test @ 5.5 Days
Resistance and Amplitude Deteriorating after 5.5 Days of elevated temperature (100C) and elevated VBias
HGA Level Accelerated Life Test
Up to 8 simultaneous HGA testing
Temperature Test
Transfer Curve
Parametrics vs. Temperature
Benefits of Thermal Reliability Testing
Accelerated Life Testing Can Predict Failures Before They Occur
Row Level Testing Provides Early Look at Thermal Reliability
Conclusion
Don’t loose your head over
ESD, Instability or Reliability
Whatever you do, QST Testing can Help!
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] H. Patland, W. Ogle, “High Frequency Instabilities in GMR Heads Due to Metal-To-Metal Contact ESD Transients”, EOS/ESD Symposium 2002
[4] Integral Solutions Int’l, “Quasi 97” and “QST-2002” Tester
Acknowledgements
Al Wallash –Maxtor Mark Nichols –Maxtor