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 [email protected] www.isiguys.com. Welcome to Complex World of GMR Head.
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Is There an ultimate test solution for manufacturing GMR heads with good Yield, Reliability and Cost?
(Semiconductor Process, Test)
(Wafer Slicing, Row Level Lapping, Test)
(Row Dicing, Slider Level Lapping, Test)
(Assy from Sliders, Suspension, FCBA’s, Test)
(Assy from HGA’s, Actuator, VC, FCBA’s, Preamp Chip, Test)
(Assy from HSA’s, Media, Enclosures, Drive PCB, Servo,Test)GMR Manufacturing Process
How many places in your manufacturing process can GMR elements get damaged?
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 don’t live in ideal world.
Close To Ideal Transfer Curve
Quasi Static Testing can characterize the GMR performance,
with the following advantages over DET Testing:
Parametrics extracted from QST Transfer Curve
Single Bit Jumps (Kinks)
Field Instability at 40 Oe
Kink / MaxSlope
Writer Induced Instabilities
No Amplitude – Hard Damage
Amplitude variation in Drive caused by High Hysteresis shown in Transfer Curve
Multiple distributed melting points
HBM: 10% Resistance Change
CDM: 100% Resistance ChangeQST can characterize ESD damage by applying a controlled ESD events to GMR head
As Al Wallash – Maxtor would put it:
“Don’t loose your head over ESD”
Whatever you do, QST Testing can Help!
CDM Failure Threshold at 5V
 J.Himle, R.Cross, M.Greenwell, “Drive-Level Instabilities Correlated to Quasi-Static Field Testing”, MMM-Intermag 2001
 C. Moore, “A Comparison of Quasi-Static Characteristics and Failure Signatures of GMR Heads subjected to CDM and HBM ESD Events”
 Integral Solutions Int’l, “Quasi 97” and “QST-2002” Tester