4. Quasi Static Tester (QST-88 plus)
STS QST-88 plus, Quasi-Static tester is a complete solution to GMR
heads electrical characterization. The QST-88 plus supports testing
of HGA, HSA, HDA, and tape MR heads with very simple tester
conversion. The unique magnetic system design allows software
programmable generation of Easy and Hard axis curves, without
mechanical adjustment. All test modules are incorporated in one
software package, eliminating the necessity to purchase additional
software and hardware modules. Calibration is automatic, keeping
maintenance costs minimal.
5. Test Parameters
• Amplitude, Asymmetry, Asymmetry Range;
• Sensitivity;
• Barkhausen Jump, Jump Location;
• delta R, delta R/R, Bias Angle, and Bias Point;
• Hysteresis;
• Pulse Test, Head Instability, RIS/WIS, Avalanche;
• AC Amplitude, AC Slope, Total Harmonic Distortion
measured during sin wave magnetic field stimulation of the head;
• Capacitance and electromechanical characteristics of Piezo
micro actuators.
QST-88 plus
6. HGA tests
• MR Resistance;
• Writer resistance;
• MR Short/Open;
• MR Polarity (Pin Layer Reversal);
• Writer Short/Open
• Writer impedance with Frequency up to 200 MHz
• Non Linear Distortion
QST-88 plus
7. Voice Coil (VC) tests
· Resistance;
· Short/Open connections;
· Presence of Shorted turns
· Resistance to ground;
· Polarity.
QST-88 plus
8. Preamp Chip tests
· Controllability of the chip
· Functionality in all modes
· Power Consumption and Power Margins in all modes,
user definable Iw and Ib
· Write current settlement
· Fault Line
· Write output multiplexer or shorts in the writer area
· RD-P/RD-N Offset
QST-88 plus
9. Flex circuit tests
· Passive components measurement
· Resistance between flex ground and HSA body
· Flex circuit trace fracture or shorts
(tested through the chip's functionality)
QST-88 plus
10. SOFTWARE FEATURES (on debugging stage)(on debugging stage)
Engineering and production modes
Graphics representation in both Production and Engineering modes
User-definable output file and data base structure
Write stimulation before transfer curve acquisition with
user definable write frequency and write current
Noise Reduction option
User definable curves filtration
"On-click" data representation from each curve
User selectable list of measurable parameters with universal
grading system
QST-88 plus
11. ELECTRICAL CHARACTERISTICS
Maximum Transversal field swing: ± 800 Oe (Custom made +/- 2000)
Transfer curve resolution: 4000 steps/swing;8000 points/test
Maximum Longitudinal field swing ± 400 Oe
Magnetic Field Application Modes 4 Modes: Constant field, Constant
angle with user selectable polarity
Data acquisition resolution Two 16-bit ADCs, one for head's
signal, and one for field coordinate
Curve acquisition time 60 ms without NR, 500 ms with NR
Measurement channel bandwidth 0 - 50 kHz
Measurement channel Noise (to input) < 1 uV
ADC sampling rate 200 kHz
QST-88 plus
12. MEASUREMENT ACCURACY
MR Resistance Measurement HGA level ± 1%
MR Resistance Measurement HSA level preamp dependent
Writer Resistance Measurement < .2 Ohms
Preamp Current Consumption ± 0.15 mA
Voice Coil Resistance Measurement ± 0.03 Ohms
AC TEST
Head Stimulation with low distortion sine wave magnetic field
(up to 100 Oe, user definable);
Precise measurement of the head's response and all harmonic distortions
from 2nd to 5th, with total distortion level calculation.
QST-88 plus
13. Pop Corn (WIS and RIS)
User-definable multi-iteration test with multi-threshold,
multi-Fw, and multi-Ibias conditions, including avalanche
mode, data processing, and abort on user specified conditions
Pulse Noise test may be performed with any
combination of transversal and longitudinal fields
Accumulated results for multiple run tests
QST-88 plus
14. Pop Corn test (WIS and RIS)Pop Corn test (WIS and RIS)
The transient time of the channel 0.1 usThe transient time of the channel 0.1 us
Direct analog test algorithm without digitizingDirect analog test algorithm without digitizing
24 bit pulse counters (with capacity of 16,777,215)24 bit pulse counters (with capacity of 16,777,215)
Modes for magnetic field stimulation during Pop CornModes for magnetic field stimulation during Pop Corn
Test:Test:
– Linearly changing transversal field (up to +- 800 Oe swing)Linearly changing transversal field (up to +- 800 Oe swing)
– DC transversal field (up to +/-400 Oe)DC transversal field (up to +/-400 Oe)
– Linearly changing longitudinal field (up to +/- 400 Oe swing)Linearly changing longitudinal field (up to +/- 400 Oe swing)
– DC longitudinal field (up to +/-400 Oe)DC longitudinal field (up to +/-400 Oe)
– Any combination of linearly changing or DC transversal andAny combination of linearly changing or DC transversal and
longitudinal fields (constant direction or rotating field)longitudinal fields (constant direction or rotating field)
– Sinusoidal transversal field with up to 100 Oe amplitudeSinusoidal transversal field with up to 100 Oe amplitude
16. Measurement Settings
Write Stimulation : Frequency up to 800 MHz
Write mode Time User definable: 0.1 µs to 1.6 s, step 0.1 µs
W/R delay User definable: 0.1 µs to 1.6 s, step 0.1 µs
Counting time (read mode)User definable: 0.1 µs to 1.6 s, step 0.1 µs
Threshold(s) User definable: 0 - 100 mV via 16 bit DAC
System Write/Read recovery time: 0.1 µs
Low-pass Filters: 30 MHz or 80 MHz
QST-88 plus
17. Measurement Settings (CONT)
•Measurement channel Bandwidth HGA configuration 1 - (50-100) MHz
HSA configuration 1 - 100 MHz
•Measurement channel Noise, recalculated to the RDP - RDN outputs
of the preamp in HSA configuration 4 nV / SQRT (Hz)
•Measurement channel Noise, recalculated to the head output in HGA
configuration 0.6 nV /
•Pulse counter : 24 bit counter (up to 16777215 pulses)
•Magnetic field stimulation during RIS and/or WIS
a) Triangle Transversal - up to ± 800 Oe
b) DC Transversal - up to ± 400 Oe
c) Triangle/DC Longitudinal - up to ± 400 Oe
d) Any combination of Transversal and Longitudinal from a), b), and c).
QST-88 plus
18. PIEZO DRIVER TEST
User definable Single or Differential stimulation with
voltage from -70 V to +70 V
Electromechanical frequency analysis within bandwidth up
to 50 kHz
Resolution 6 Hz
Extremely high performance (single test time 0.5 s).
Accurate detection of
- Broken or partially damage piezo
- Wire bonding/connection
- Open and or short
QST-88 plus
19. Reliability
Power supply protection with automaticPower supply protection with automatic
voltage selectorvoltage selector
Fiber optics connection between PC andFiber optics connection between PC and
tester eliminates possibility of tester damagetester eliminates possibility of tester damage
due to bad grounding system of the facilitydue to bad grounding system of the facility
Reliable mechanism without lead screws orReliable mechanism without lead screws or
pneumaticspneumatics
Easy interchangeability of toolingEasy interchangeability of tooling
Self-calibration on turning on with self-Self-calibration on turning on with self-
diagnostics.diagnostics.
All measurements in the system areAll measurements in the system are
performed differentially.performed differentially.
23. Transfer CurveTransfer Curve
16 bit independent DACs for both horizontal and vertical16 bit independent DACs for both horizontal and vertical
coordinatescoordinates
Highest resolution in the industry for transfer curveHighest resolution in the industry for transfer curve
acquisitionacquisition 8,0008,000 points per test instead ofpoints per test instead of 400400 points frompoints from
our competitor.our competitor.
50 KHz bandwidth of TC channel, with 5 pole low pass filter to50 KHz bandwidth of TC channel, with 5 pole low pass filter to
avoid distortions and 200 KHz sampling rate.avoid distortions and 200 KHz sampling rate.
Extremely low noise level of the TC channel: about 0.5...1 uVExtremely low noise level of the TC channel: about 0.5...1 uV
RMSRMS
The magnet current generator design is able to provideThe magnet current generator design is able to provide
transverse magnetic field swing up to 2000 Oe and longitudinaltransverse magnetic field swing up to 2000 Oe and longitudinal
magnetic field up to 800Oe with special power supply unitmagnetic field up to 800Oe with special power supply unit
(simple replacement )(simple replacement )
