Sae Magnetics (h.k.) Limited

Tdk Corporation

Sae Magnetic (h.k.), Ltd.

Juren Ding

Rongkwang Ni

Cheukwing Leung

Chiuming Lueng

Mankit Lee

Cheukman Lui

Wanyin Kwan

Hokei Lam

Kazuki Sato

Yasutoshi Fujita

Wahchun Chan

Lorest Garcia Pingul

Kwokkam Leung

Chiyuen Mok

Siuman Mok

Kosuke Tanaka

Yohei Koyanagi

Lu Xiao

Shenkuang Chou

Kayip Wong

Kaichiu Cheung

Liping Peng

Yanbin Wang

Wah Chun Chan

Wai Bun Ow

Ho Kei Lam

Cheuk Man Lui

Kai Chiu Cheung

Chiuming Leung

Yuk Sing Lo

A manufacturing method of a slider includes steps of: (a) providing a row bar with a plurality of slider elements connecting together; (b) lapping surfaces of the row bar so as to obtain a predetermined requirement; (c) lowering the temperature of the surfaces lapped in the step (b) before and/or during lapping; and (d) cutting the row bar into a plurality of sliders. The present invention can prevent a local high temperature generated on the magnetic head during lapping so that the performance of the magnetic head is improved.

Manufacturing method of a slider

A method of testing anti-high temperature performance of a magnetic head comprises applying a plurality of second magnetic fields with different intensities in a second direction to the magnetic head, and measuring a second output parameter curve, and judging whether a variation that is beyond an allowable value is presented on the second output parameter curve, therein the second direction passes through the ABS and at an angle whose absolute value is an acute angle to the ABS. The present invention can screen out defective magnetic heads that possess poor anti-high temperature performance without heating the magnetic head.

Method of testing anti-high temperature performance of a magnetic head and apparatus thereof

A testing method of a magnetic head includes: applying a first magnetic field with a constant intensity in a first direction that is the same with that of the longitudinal bias field to the magnetic head, simultaneously applying a second magnetic field with variant intensities in a second direction traversing the air bearing surface, and measuring a first noise; applying a third magnetic field with a constant intensity in a third direction that is opposite to the first direction to the magnetic head, simultaneously applying the second magnetic field with variant intensities in the second direction, and measuring a second noise; and analyzing noise change between the first noise and the second noise. The invention can screen out defective magnetic heads that possess poor noise characteristic and unstable performance.

Testing method of a magnetic head, and testing apparatus thereof

A method for evaluating bit error rate for a magnetic head by using a quasi-static test system, includes step (a), measuring a noise characteristic curve for a magnetic head, and the noise characteristic comprising noise amplitude and maximum noise amplitude; step (b), constructing a noise waveform by appropriately scaling a signal noise ratio of the magnetic head based on the noise characteristic curve measured in step (a); and step (c), injecting the noise waveform constructed in step (b) into a model comprising a transmitter module and a receiver module to evaluate a bit error rate. The method saves testing time, reduces manpower, and obtains accuracy testing result.

Method for evaluating bit error rate for a magnetic head by using a quasi-static test system, and system thereof

A method of testing anti-high temperature performance of a magnetic head comprises applying a second magnetic field with different intensities in a second direction and the changing first magnetic fields in a first direction, and measuring a plurality of second output parameter curves; and judging whether a variation that is beyond an allowable value is presented on the second output parameter curves, thereby screening out a defective magnetic head, therein the first direction is perpendicular to the air bearing surface of the magnetic head, and the second direction is perpendicular to the shielding layers of the magnetic head. The present invention can screen out defective magnetic heads that possess poor anti-high temperature performance without heating the magnetic head and with high precision.

A reader sensor comprises a first shielding layer, a second shielding layer, a read element formed therebetween, and a pair of permanent magnet layer respectively placed on two sides of the read element; and it further comprises a magnetic field generating means formed beside the read element and arranged for providing a magnetic field with a direction perpendicular to the first shielding layer and the second shielding layer, thereby stabilizing the reading performance of the reader sensor. The invention can stabilize the reading performance, ameliorate the unstable defective reader sensor, and decrease the waste and the manufacturing cost. The present invention also discloses a magnetic head, a HGA and a disk drive unit.

Reader sensor, magnetic head, head gimbal assembly and disk drive unit with the same

A manufacturing method of a slider includes steps of (a) providing a row bar with a plurality of slider elements connecting together, the row bar having an air bearing surface, a back surface opposite the air bearing surface, a bonding surface and a bottom surface opposite the bonding surface; (b) grinding the bottom surface of the row bar; (c) lapping the air bearing surface of the row bar so as to obtain a predetermined requirement, and applying a first magnetic field with a first direction during lapping the air bearing surface, and the first direction being parallel to the air bearing surface and the bonding surface; and (d) cutting the row bar into a plurality of individual sliders. The present invention can maintain a good performance of a magnetic head during the manufacturing process.

Manufacturing method of a slider and manufacturing apparatus thereof

A spectral simulation method during a noise testing for a magnetic head, includes steps of (a1) detecting several first noise profiles for several magnetic head samples under a first frequency bandwidth range by a dynamic testing machine; (b1) separating each first noise profile into at least two noise curves including a first noise curve and a second noise curve at a predetermined frequency bandwidth, wherein the first noise curve has a frequency bandwidth range lower than that of the second noise curve; (c1) fitting several mathematical equations according to the second noise curves; and (d1) establishing a correlative equation among the mathematical equations, so as to simulate the second noise curve for each magnetic head. The present invention can simulate a second noise curve of the noise profile in a higher frequency bandwidth and establishing the correlative equation according to the second noise curve.

Spectral simulation method during noise testing for a magnetic head, and noise-testing method for a magnetic head by using the same

An MR sensor includes a first shielding layer, a second shielding layer, an MR element formed therebetween, and a pair of hard magnet layers respectively placed on two sides of the MR element. The MR element includes an AFM layer formed on the first shielding layer, a pinned layer formed on the AFM layer and a free layer formed between the pinned layer and the second shielding layer. The free layer is funnel-shaped, which has a first edge facing an air bearing surface and a second edge opposite the first edge, and the first edge has a narrower width than that of the second edge. The MR sensor can improve MR height control performance, and improve the ESD performance and decrease the PCN and RTN and, in turn, get a more stable performance. The present invention also discloses a magnetic head, an HGA and a disk drive unit.

Magnetoresistive sensor with funnel-shaped free layer, magnetic head, head gimbal assembly, and disk drive unit with the same

A method for measuring longitudinal bias magnetic field in a tunnel magnetoresistive sensor of a magnetic head, the method includes the steps of: applying an external longitudinal time-changing magnetic field onto the tunnel magnetoresistive sensor; determining a shield saturation value of the tunnel magnetoresistive sensor under the application of the external longitudinal time-changing magnetic field; applying an external transverse time-changing magnetic field and an external longitudinal DC magnetic field onto the tunnel magnetoresistive sensor; determining a plurality of different output amplitudes under the application of the external transverse time-changing magnetic field and the application of different field strength values of the external longitudinal DC magnetic field; plotting a graph according to the different output amplitudes and the different field strength values; and determining the strength of the longitudinal bias magnetic field according to the graph and the shield saturation value.

Method for measuring longitudinal bias magnetic field in a tunnel magnetoresistive sensor

A close loop method for measuring head SNR, for a storage device comprising a storage media and a head, comprising steps of: (a) loading the head on the media with a dynamic fly height; (b) measuring an initial environmental temperature value T1 and measuring the head signal signal; (c) unloading the head; (d) adjusting a power which controls the dynamic fly height until a real-time environmental temperature value T2 is equal to the initial environmental temperature T1; (e) measuring the head noise value noise, (f) calculating the head SNR with the follow equation: The method of the present invention can obtain a fair condition between the signal and noise measurement, thereby a reliable and accurate head SNR can be obtain. The present invention also provides a close loop method for measuring media SNR.

Close loop method for measuring head SNR and media SNR

A method for measuring a temperature rise induced by bias current/bias voltage in a magnetic tunnel junction includes: (a) applying an external time-changing magnetic field to the magnetic tunnel junction; (b) measuring different first outer pin flip field values under different temperature values; (c) correlating the temperature values with the outer pin flip field values; (d) measuring different second outer pin flip field values under different bias current/bias voltage values; (e) correlating the different bias current/bias voltage-values with the measured different second outer pin flip field values; and (f) correlating temperature values and bias current/bias voltage values according to the results produced by (c) and (e). The method can determine what kind of TMR reader design provides more stable and reliable reading performance, especially under higher operational temperatures.

Method for measuring the temperature rise induced by bias current/bias voltage in a magnetic tunnel junction

A MR sensor comprises a first shielding layer, a second shielding layer, a MR element and a pair of hard magnet layers sandwiched therebetween, and a non-magnetic insulating layer formed at a side of the MR element far from an air bearing surface of a slider. The MR sensor further comprises a first non-magnetic conducting layer formed between the first shielding layer and the MR element, and the first non-magnetic conducting layer is embedded in the first shielding layer and kept separate from the ABS. The MR sensor of the invention can obtain a narrower read gap to increase the resolution power and improve the reading performance, and obtain a strong longitudinal bias field to stabilize the MR sensor so as to increase the total sensor area and, in turn, get an improved reliability and performance. The present invention also discloses a magnetic head, a HGA and a disk drive unit.

Magnetoresistive sensor, including non-magnetic conducting layer embedded in shielding layer and magnetic head, head gimbal assembly and disk drive unit with the same

A slider for a head gimbal assembly includes a trailing surface, a plurality of connection pads arranged on the trailing surface adapted for both bonding the slider to a suspension of the head gimbal assembly and testing the performance of the slider. At least a part of the connection pads each comprises a bonding portion and a testing portion electrically connected to the bonding portion and larger than the bonding portion, all the bonding portions and the rest part of the connection pads are arranged in a first row and the testing portions are arranged outside the first row. The slider of the present invention has a new pad layout to facilitate bonding of the connection pads and permit to provide additional pads thereon to connect the additional sensors therein for precise reading and writing, thereby improving the performance of the slider. The invention also discloses a head gimbal assembly and a disk drive unit including the same.

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Hong Kong, China

Juren Ding