Electrostatic Discharge (esd) Protection Patents (Class 360/323)
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Patent number: 6643106Abstract: An intermediate article of manufacture of a magnetoresistive head with a protective device having sensor elements with terminal pads and a shunt element connected across the sensor element for shunting the sensor element to discharge static electrical charge during the manufacture of the magnetoresistive head. The shunt element is a piece of solder extending between the first and second terminals.Type: GrantFiled: July 13, 2001Date of Patent: November 4, 2003Assignee: Seagate Technology LLCInventors: Zine-Eddine Bougtaghou, Peter R. Segar
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Patent number: 6633459Abstract: The invention is a magnetoresistive recording head including the reader portion that has a top and bottom shield, a first auxiliary electrical connection, a second auxiliary electrical connection, a first auxiliary electrical contact, and a second auxiliary electrical contact, where the first auxiliary electrical connection electrically connects the first auxiliary electrical contact to the top shield, and where the second auxiliary electrical connection electrically connects the second auxiliary electrical contact to the bottom shield.Type: GrantFiled: June 18, 2001Date of Patent: October 14, 2003Assignee: Seagate Technology LLCInventors: Kevin Richard Heim, Clifton H. Chang, Peter Thomas Weyandt, Patrick Joseph Ryan
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Patent number: 6631052Abstract: The present invention provides a method for the creation and removal of shunts for the prevention of ESD/EOS damage to electrical components. In one embodiment of the present invention, the conductive pathway is provided and removed by exposing the interconnect's carbonizable and ablatable substrate to a radiant energy source such as a laser beam. The present invention also provides for interconnects that include at least two conductive wires or leads engaged on at least one surface by a carbonizable and ablatable material. The conductive wires may each include a branched dead end lead portion interleaved with the branched dead end lead portion of the other. Alternatively, the conductive wires may extend in close proximity to each other in a curved or sinuous or serpentine or backtracking pattern.Type: GrantFiled: August 11, 1999Date of Patent: October 7, 2003Assignee: Applied Kinetics, Inc.Inventors: Mark T. Girard, Ryan A. Jurgenson
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Patent number: 6631056Abstract: On a wafer-like substrate 1, there are formed a number of thin film magnetic head elements in matrix, each of which is formed to include a first shield film 3 formed on the wafer-like substrate 1, a first insulating film 71 formed on the first shield film, a magnetoresistive element 9 and first and second electrode films 11, 13 connected to respective ends of the magnetoresistive element formed on the first insulating film, a second shield film 5 formed to cover the magnetoresistive element and first and second electrode films 11, 13, a second insulating film 72 formed on the second shield film, and a conductive film 191 electrically connected to the first electrode film 11 and second shield film 5 and having a middle portion which is separated from a side edge of the second shield film 5 by a distance &Dgr;G2 viewed in a film stacking direction.Type: GrantFiled: June 1, 2000Date of Patent: October 7, 2003Assignee: TDK CorporationInventors: Takashi Asatani, Fujimi Kimura, Junichi Sato
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Publication number: 20030184920Abstract: Methods and apparatus for protecting read sensors from damage caused by electrostatic discharge (ESD) during manufacturing are described. Two electrical connections are formed and utilized for ESD protection: one primarily for early protection of the sensors (i.e. prior to cutting and lapping the wafer to form the ABS) and the other primarily for later protection of the sensors (i.e. after cutting and lapping the wafer to form the ABS). The first electrical connection is created between the read sensor and the first and second shields, and is severed when the wafer is cut and lapped along the ABS. The second electrical connection is formed between the sensor leads and the first and second shields, and is exposed on an outside surface of the magnetic head. The second electrical connection is severed late in the manufacturing process, preferably by laser-deletion.Type: ApplicationFiled: March 28, 2002Publication date: October 2, 2003Inventors: James Devereaux Jarrett, Richard Hsiao, Ciaran Avram Fox, Edward Hin Pong Lee, Thomas Robert Albrecht
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Patent number: 6625857Abstract: A method of forming a capacitive element for a circuit board or chip carrier having improved capacitance is provided. The element is formed from a pair of conductive sheets having a dielectric component laminated therebetween. The dielectric component is formed of two or more dielectric sheets, at least one of which can be partially cured followed by being fully cured. The lamination takes place by laminating a partially cured sheet to at least one other sheet of dielectric material and one of the conductive sheets. The total thickness of the two sheets of the dielectric component does not exceed about 4 rolls and preferably does not exceed about 3 mils; thus, the single dielectric sheet does not exceed about 2 mils and preferably does not exceed about 1.5 mils in thickness.Type: GrantFiled: February 1, 2001Date of Patent: September 30, 2003Assignee: International Business Machines CorporationInventors: Bernd K. Appelt, John M. Lauffer
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Publication number: 20030169539Abstract: The invention provides a magnetoresistive read head comprising a bottom shield and a top shield. The bottom shield and the top shield are spaced apart to form a read gap. A magnetoresistive sensor and a resistive layer are disposed within the read gap whereby any electric charge developed across the read gap layer is dissipated to thereby prevent any electrostatic discharge damage to the magnetoresistive read head. The resistive layer is preferably made from a cermet family of films.Type: ApplicationFiled: March 7, 2002Publication date: September 11, 2003Applicant: International Business Machines CorporationInventor: Howard G. Zolla
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Publication number: 20030169540Abstract: A magnetoresistive head assembly of the present invention includes a magnetoresistive sensor and an electrostatic discharge and electrical overstress protection circuit. The magnetoresistive is capable of having conducted therethrough oppositely-directed first direction current and second direction current. The magnetoresistive sensor is sensitive to first direction currents in excess of a first predetermined value and to second direction currents in excess of a second predetermined value different than the first predetermined value. The electrostatic discharge and electrical overstress protection circuit is electrically connected to the magnetoresistive sensor for preventing only those first direction currents greater than the first predetermined value from flowing though the magnetoresistive sensor and only those second direction currents greater than the second predetermined value from flowing through the magnetoresistive sensor.Type: ApplicationFiled: August 1, 2002Publication date: September 11, 2003Applicant: Saegate Technology LLCInventors: Eric Leroy Granstrom, Ned Tabat
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Publication number: 20030151858Abstract: A multi-layer electrically conductive shunt is located on the exterior surface of a slider in electrical contact and extending between first and second lead ends of leads that are connected to a sensor of a read head. Electrically conductive spaced apart first and second read pads are located on the conductive shunt in electrical contact with the first and second lead ends via the conductive shunt. The conductive shunt includes a thick gold layer which is located between and interfaces an adhesion layer and a cap layer wherein the adhesion layer makes direct electrical contact with the aforementioned first and second lead ends.Type: ApplicationFiled: February 11, 2002Publication date: August 14, 2003Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Richard Hsiao, James Devereaux Jarratt, Chie Ching Poon
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Publication number: 20030142444Abstract: A system and method for the prevention of electrostatic discharge (ESD) by a hard drive magnetic head is disclosed. The magnetic head is secured to a head-gimbal assembly (HGA) by anisotropic conductive paste (ACP) to provide an improved electrostatic discharge path.Type: ApplicationFiled: July 26, 2002Publication date: July 31, 2003Inventors: Bin Hua Tan, Quan Sheng Wu, Ze Liang Luo, Yu Fu
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Patent number: 6583968Abstract: An aspect of the invention can be regarded as a disk drive that includes a disk drive base and a magnetic disk. The disk drive further includes a rotary actuator coupled to the disk drive base. The rotary actuator has an MR read element disposed adjacent the magnetic disk. The MR read element has a bias voltage. The disk drive further includes a rotatable spindle motor hub for rotating the magnetic disk positioned on the spindle motor hub. The spindle motor hub is in electrical communication with the magnetic disk. The spindle motor hub is mechanically coupled to and electrically insulated from the disk drive base. The disk drive further includes a circuit for applying a voltage equivalent to the bias voltage to the spindle motor hub such that a voltage potential between the MR read element and the magnetic disk is mitigated.Type: GrantFiled: October 31, 2001Date of Patent: June 24, 2003Assignee: Western Digital Technologies, Inc.Inventors: John E. Scura, Hossein M. Moghadam
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Publication number: 20030112563Abstract: A head substrate and a protective substrate are formed of an electrostatic-discharge resistant conductive material having an electrical resistivity of 102 to 1010 &OHgr;cm. These substrates are electrically connected to a base metal through the use of conductive paste and are set to a ground potential via the base metal and a rotating drum. This suppresses a discharge current flowing through an MR element when an electrostatically charged substance touches or approaches a magnetic reproducing head, a terminal, a conducting wire, etc. to generate an electrostatic discharge. The magnetic reproducing head including an MR element and the like is prevented against an electrostatic discharge damage. It is possible to provide the magnetic reproducing head, a head drum apparatus, and a magnetic recording-reproducing apparatus which can highly effectively prevent an electrostatic discharge damage.Type: ApplicationFiled: October 9, 2002Publication date: June 19, 2003Inventors: Yutaka Souda, Yoshimi Takahashi, Susumu Sato, Seiji Onoe
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Patent number: 6574078Abstract: A magnetic head using a mechanical switch and an electrostatic discharge device network is disclosed. A mechanical switch is in series and parallel configuration with a silicon electrostatic discharge network. The electrostatic discharge network can be controlled in an on or off state for testing, evaluation or diagnostics of the armature or MR head.Type: GrantFiled: June 23, 2000Date of Patent: June 3, 2003Assignee: International Business Machines CorporationInventor: Steven H. Voldman
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Patent number: 6552880Abstract: The present invention may be regarded as a disk drive with protection against damage due to a thermal asperity. The disk drive comprises a disk having a surface with an asperity, and a magneto-resistive head actuated radially over the surface of the disk for generating a read signal comprising a thermal asperity component caused by the magneto-resistive head contacting the asperity on the surface of the disk. A bias generator is provided for generating an electrical bias applied to the magneto-resistive head, and a thermal asperity detector detects the thermal asperity component in the read signal. When the thermal asperity component is detected, the electrical bias is reduced for a time interval, thereby protecting the magneto-resistive head.Type: GrantFiled: January 31, 2001Date of Patent: April 22, 2003Assignee: Western Digital Technologies, Inc.Inventors: Gary L. Dunbar, David M. Hannon, James Weispfenning, Jodie A. Christner, Timothy Bouwkamp
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Patent number: 6552879Abstract: An ESD protective circuit is described which has a very low, variable turn-on threshold by using a shunting MOSFET which has an isolated substrate/body which is connected to an electrode that is provided in addition to the gate, source and drain electrodes. A variable gate voltage which is preferably a function of an ESD voltage is used to trigger the MOSFET into conduction. A voltage is applied to the substrate/body of the MOSFET to lower the turn-on voltage. The voltage on the substrate allows the turn-on voltage to be adjusted for different applications and/or to be adjusted dynamically to respond to events. The substrate voltage is also preferably derived from the ESD voltage. Preferably the MOSFET has an epitaxial region with an electrode and a subcollector with an electrode. The epitaxial region electrode can be connected to the gate to improve the turn-on performance. The subcollector electrode can be connected to the substrate/body electrode to contribute to lowering the turn-on voltage.Type: GrantFiled: January 23, 2001Date of Patent: April 22, 2003Assignee: International Business Machines CorporationInventor: Steven Howard Voldman
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Patent number: 6538861Abstract: A magnetoresistive head whose operation depends on a magnetoresistive effect is configured using a ferromagnetic tunnel junction (MTJ) film, which is arranged between a lower electrode and an upper electrode. The ferromagnetic tunnel junction film is basically configured using a set of a free layer, a barrier layer and a fixing layer, which are sequentially formed and laminated on the lower electrode. Herein, the ferromagnetic tunnel junction film is designed to avoid electrostatic destruction in manufacture by prescribed measures. For example, the barrier layer is reduced in thickness at a terminal portion as compared with a center portion. Or, the barrier layer has a defect at the terminal portion. In addition, it is possible to provide a conductor in connection with the barrier layer in proximity to its terminal portion.Type: GrantFiled: June 19, 2000Date of Patent: March 25, 2003Assignee: NEC CorporationInventors: Kazuhiko Hayashi, Masafumi Nakada, Eizo Fukami, Kiyokazu Nagahara, Hiroaki Honjou, Kunihiko Ishihara, Tamaki Toba, Hisanao Tsuge, Atsushi Kamijo
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Patent number: 6538857Abstract: A read head is provided with an N-cycle switch for sequentially shorting and unshorting a sense current circuit of a read head so that the read head will be protected from electrostatic discharges (ESDs) by shorting when the read head is not being tested and unshorted during tests of the read head. The shorting and unshorting switches, which are mounted on or in a slider carrying the read head, are activated by a laser beam.Type: GrantFiled: September 14, 2000Date of Patent: March 25, 2003Assignee: International Business Machines CorporationInventors: Saad Doss, Glen Adam Garfunkel, Edward Hin Pong Lee, Chie Ching Poon, Neil Leslie Robertson, Andrew Ching Tam
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Publication number: 20030035252Abstract: The invention provides a magnetic head capable of positively preventing electrostatic breakdown of an MR magnetic head device, and a method of manufacturing the magnetic head. A circuit board comprises at least a pair of leads for constructing a circuit, lands connected respectively to the leads, and solder bumps formed respectively on the lands. The solder bumps are arranged in an adjacent relationship and, when the solder bumps are crushed, peripheral portions of the solder bumps are pressed or spread so as to overlap with each other. The magnetic head includes the circuit board.Type: ApplicationFiled: October 2, 2002Publication date: February 20, 2003Applicant: ALPS ELECTRIC CO., LTD.Inventors: Michiharu Motonishi, Michiaki Moroe
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Patent number: 6507466Abstract: In a magnetoresistive effect head in which a magnetoresistive effect element made from either a ferromagnetic tunnel junction film or a spin valve film is formed as a magnetoresistive sensor, a diode is connected in parallel with a first and a second electrode of the magnetoresistive effect element.Type: GrantFiled: April 24, 2000Date of Patent: January 14, 2003Assignee: NEC CorporationInventors: Kazuhiko Hayashi, Keishi Ohashi
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Patent number: 6507467Abstract: An apparatus for protecting a magnetoresistive head from electrostatic discharge. The apparatus includes an actuator assembly including the magnetoresistive head, and a connector board including a plurality of conductive traces in electrical contact with the magnetoresistive head. The connector board defines a plurality of openings therein, each of the openings having sides surfaces in electrical contact with one of the traces. The apparatus further includes a conductive shunting member including a plurality of protruding members adapted to be inserted into the openings and contact the side surfaces of the openings. The shunting member, when so inserted into the openings shorts the traces to provide protection of the magnetoresistive head from electrostatic discharge.Type: GrantFiled: August 17, 2000Date of Patent: January 14, 2003Assignee: Seagate Technology LLCInventors: Frank William Schadewald, Jr., Mark James Schaenzer, Scott Michael Franzen
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Patent number: 6470566Abstract: To protect the MR read head element from ESD damage during wafer level manufacturing, a lead from the MR element is electrically connected to one or both of the read head element shields during manufacturing. In a preferred embodiment of the present invention, the electrical connection is fabricated in the kerf area between adjacent magnetic heads as they are fabricated upon a wafer substrate. Thereafter, when the magnetic heads are separated by saw cutting through the kerf areas, the electrical connections are thereby removed, such that the MR element electrical leads and the shields are electrically isolated. In an alternative embodiment, one or more of the shields, as well as the MR element leads can also be electrically connected to the substrate upon which the magnetic head is fabricated.Type: GrantFiled: January 3, 2001Date of Patent: October 29, 2002Assignee: International Business Machines CorporationInventors: Richard Hsiao, Edward Hin Pong Lee, Timothy J. Moran, Joseph Francis Smyth, Howard Gordon Zolla
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Publication number: 20020154454Abstract: A head gimbal assembly that includes a bleed resistor applied over a specified area of the reader, writer and ground leads in order to protect from ESD damage is disclosed. The present invention address the need for an ESD protection system that includes a consistent and secure connection with leads, that does not contaminate the drive environment and applies a consistent resistivity to both the reader and writer element by providing a head gimbal assembly with strategically placed bleed resistors that will protect the read element from transient charge produced any time during the fabrication, assembly, testing and shipment of the disc drive.Type: ApplicationFiled: April 2, 2002Publication date: October 24, 2002Inventors: Paul E. Kupinski, Ned Tabat, Marsha A. Huha, Kevin J. Schulz, Werner Weidemann, Eric L. Granstrom, Clifton H.K. Chang
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Publication number: 20020149888Abstract: The invention provides a magnetic head capable of positively preventing electrostatic breakdown of an MR magnetic head device, and a method of manufacturing the magnetic head. A circuit board comprises at least a pair of leads for constructing a circuit, lands connected respectively to the leads, and solder bumps formed respectively on the lands. The solder bumps are arranged in an adjacent relationship and, when the solder bumps are crushed, peripheral portions of the solder bumps are pressed or spread so as to overlap with each other. The magnetic head includes the circuit board.Type: ApplicationFiled: April 10, 2002Publication date: October 17, 2002Inventors: Michiharu Motonishi, Michiaki Moroe
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Publication number: 20020126424Abstract: A magnetoresistive transducer includes a substrate and a magnetoresistive assembly. At least one bleed resistor couples the magnetoresistive assembly to the substrate. The bleed resistor has a relative large electrical resistance and provides a discharge path for accumulated charge. The arrangement effectively prevents electrostatic discharge damage to the sensor.Type: ApplicationFiled: April 2, 2001Publication date: September 12, 2002Inventors: Ned Tabat, Paul E. Kupinski
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Patent number: 6427319Abstract: A method for protecting magnetic read/write head assembly against electrostatic discharge during disk drive manufacturing are disclosed. The magnetic head assembly is supported on a substrate having a magnetoresistive sensor element disposed in spaced relationship between several magnetic shield elements. Before a focused ion beam fabrication operation, at least a portion of an air bearing surface of the magnetic head assembly is coated with a thin and transparent layer of conductive material. This layer of conductive material is subsequent removed after the focused ion beam fabrication operation.Type: GrantFiled: May 15, 2000Date of Patent: August 6, 2002Assignee: International Business Machines CorporationInventors: Jack Dana Cook, Grace Lim Gorman, Cherngye Hwang
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Publication number: 20020097532Abstract: An ESD protective circuit is described which has a very low, variable turn-on threshold by using a shunting MOSFET which has an isolated substrate/body which is connected to an electrode that is provided in addition to the gate, source and drain electrodes. A variable gate voltage which is preferably a function of an ESD voltage is used to trigger the MOSFET into conduction. A voltage is applied to the substrate/body of the MOSFET to lower the turn-on voltage. The voltage on the substrate allows the turn-on voltage to be adjusted for different applications and/or to be adjusted dynamically to respond to events. The substrate voltage is also preferably derived from the ESD voltage. Preferably the MOSFET has an epitaxial region with an electrode and a subcollector with an electrode. The epitaxial region electrode can be connected to the gate to improve the turn-on performance. The subcollector electrode can be connected to the substrate/body electrode to contribute to lowering the turn-on voltage.Type: ApplicationFiled: January 23, 2001Publication date: July 25, 2002Inventor: Steven Howard Voldman
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Patent number: 6424505Abstract: A method and system for protecting a suspension assembly, such as a flex-on-suspension or trace suspension assembly, is disclosed. The suspension assembly is for use with a magnetoresistive (MR) head including an MR sensor. The MR sensor has a first end and a second end. The method and system include providing a first lead coupled with the first end of the MR sensor and providing a second lead coupled with the second end of the MR sensor. The method and system further include providing an insulating film supporting a first portion of the first lead and a second portion of the second lead. The method and system also include providing a resistor coupled with the first lead, the resistor being sufficiently large to damp a transient current in the MR sensor.Type: GrantFiled: May 6, 1999Date of Patent: July 23, 2002Assignee: Read-Rite CorporationInventors: Chung F. Lam, Caleb Kai-lo Chang, Dino Tommy Anthony Martinez
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Patent number: 6415500Abstract: Methods and structures are disclosed which avoid electrostatic charge build up and subsequent electrostatic discharge (ESD) during the wafer fabrication process of magnetoresistive (MR) or giant magnetoresistive (GMR) read/write heads of magnetic disk drives. This is achieved by designing the wafer layout and process so that the MR/GMR sensor film is shorted to the magnetic shields of the head through shorting paths so that there is an equal potential between MR/GMR sensor film and magnetic shields during the entire fabrication process.Type: GrantFiled: January 13, 2000Date of Patent: July 9, 2002Assignee: Headway Technologies, Inc.Inventors: Cherng-Chyi Han, Mao-Min Chen, Jen-Wei Koo, Rodney Lee, Li-Yan Zhu, Jei-Wei Chang
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Publication number: 20020085318Abstract: A first read gap layer has a resistance RG1 between a first shield layer and one of the first and second lead layers of a read head and the second read gap layer has a resistance RG2 between a second shield layer and said one of the first and second lead layers of the read head. A connection is provided via a plurality of resistors between a first node and each of the first and second shield layers wherein the plurality of resistors includes at least first and second resistors RS1 and RS2 and the first node is connected to said one of the first and second lead layers. A second node is located between the first and second resistors RS1 and RS2. An operational amplifier has first and second inputs connected to the first and second nodes respectively so as to be across the first resistor RS1 and has an output connected to the first node for maintaining the first and second nodes at a common voltage potential. In a first embodiment the first and second shield layers are shorted together.Type: ApplicationFiled: January 2, 2001Publication date: July 4, 2002Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Richard Hsiao, James D. Jarratt, Emo Hilbrand Klaassen, Ian Robson McFadyen, Timothy J. Moran
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Publication number: 20020075610Abstract: An electrostatic discharge protection device can protect a head gimbal assembly circuit from electrostatic discharge. The device includes a housing and a shunt positioned within the housing. The shunt includes a pair of electrical contacts and the shunt has a first position in which the electrical contacts are in electrical communication with the circuit and a second position in which the electrical contacts are removed from electrical communication with the circuit. The shunt can be placed in its first position to protect the head gimbal assembly against electrostatic discharge and is moved into its second position to permit testing operations of the head gimbal assembly. The shunt is then returned to its first position.Type: ApplicationFiled: December 17, 2001Publication date: June 20, 2002Inventors: Frank William Schadewald, Arnold Warren Johansen
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Patent number: 6404604Abstract: In a magneto-resistive effect type head having provided between a lower shield layer and an upper shield layer an MR sensor with a magneto-resistive effect or a gigantic magneto-resistive effect; electrode layers electrically connected to the MR sensor; and lower and upper insulating layers magnetically and electrically isolating the MR sensor and the electrode layer from the shield layers, when the gap length is reduced and the lower and upper insulating layers are decreased in thickness, the insulating layers are more liable to a dielectric breakdown by static electricity produced in the manufacturing process of the magnetic head.Type: GrantFiled: March 29, 2001Date of Patent: June 11, 2002Assignee: Hitachi, Ltd.Inventors: Shiroyasu Odai, Matahiro Komuro
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Patent number: 6400534Abstract: In a magnetic read/write assembly, the magnetoresistive (G)MR sensor element is protected against electrostatic discharge (ESD) and electrical overstress (EOS) by using a low resistance bypass. The low resistance bypass shunts current away from the magnetoresistive sensor element during an ESD or EOS event. This low resistance bypass is made up of two or more resistors connected in series, and positioned in parallel to the magnetoresistive sensor element. The use of electronic circuitry to temporarily disable this low resistance bypass allows the magnetoresistive sensor element to be tested during manufacturing. The low resistance bypass is removed prior to placing the (G)MR head into operation in the magnetic storage system or at any other desired step in the manufacturing process.Type: GrantFiled: March 21, 2000Date of Patent: June 4, 2002Assignee: International Business Machines CorporationInventor: Erno Hilbrand Klaassen
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Publication number: 20020060888Abstract: A magnetic head slider of the present invention includes a slider body having an air bearing surface opposed to a magnetic disk, a magnetic head including a magneto-resistance effect element provided on the slider body, first and second terminals connected to the MR element, and a switching element for short-circuiting the first and second terminals in response to an external input. With this configuration, it is possible to prevent the occurrence of damages of the MR element due to static electricity or the like. A photo-transistor is suitable as the switching element in consideration of productivity of a magnetic disk drive unit. In this case, the external input is light incident on the photo-transistor, and when the magnetic head slider is housed in a disk enclosure and is thereby shielded from light, the photo-transistor is turned off to allow a sensing current to flow in the MR element.Type: ApplicationFiled: October 29, 2001Publication date: May 23, 2002Applicant: FUJITSU LIMITEDInventor: Eiichi Kanda
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Patent number: 6377411Abstract: A head suspension assembly for use in a magnetic disk drive includes a magnetic head constituted by a magnetoresistive element for reading data and a head element for writing data, a slider for holding the magnetic head above a surface of a rotating magnetic recording medium, a suspension for supporting the slider, and a head integrated circuit mounted on the suspension. The head integrated circuit having a built-in protection circuit electrically connected with the magnetoresistive element to protect the magnetoresistive element from electrostatic breakdown. Thereby, the magnetic head can be efficiently prevented from suffering electrostatic breakdown due to, e.g., electrostatic discharge occurring during the assembly process of incorporating the head suspension assembly into the magnetic disk drive.Type: GrantFiled: August 30, 1999Date of Patent: April 23, 2002Assignee: Kabushiki Kaisha ToshibaInventors: Makoto Katsumata, Kenji Tsuruta, Katsuhiko Kaida
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Publication number: 20020044392Abstract: An intermediate article of manufacture of a magnetoresistive head with a protective device having sensor elements with terminal pads and a shunt element connected across the sensor element for shunting the sensor element to discharge static electrical charge during the manufacture of the magnetoresistive head. The shunt element is a piece of solder extending between the first and second terminals.Type: ApplicationFiled: July 13, 2001Publication date: April 18, 2002Inventors: Zine-Eddine Bougtaghou, Peter R. Segar
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Publication number: 20020036875Abstract: In a magnetoresistive head, a first non-magnetic layer is formed on a first shield layer. A magnetoresistive element includes a magnetoresistive film and an electrode portion both formed on the first non-magnetic layer. A second non-magnetic layer is formed on the magnetoresistive element. A second shield layer is formed on the second non-magnetic layer. A non-magnetic metal layer electrically connects the first and the second shield layers. A first earth member is electrically connected to the electrode portion of the magnetoresistive element. A second earth member is electrically connected to the first and the second shield layers. A third earth member is electrically connected to the first earth member and the second earth member.Type: ApplicationFiled: September 20, 2001Publication date: March 28, 2002Inventors: Satoshi Ajiki, Koichi Hosoya
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Publication number: 20020015264Abstract: The invention is a magnetoresistive recording head including the reader portion that has a top and bottom shield, a first auxiliary electrical connection, a second auxiliary electrical connection, a first auxiliary electrical contact, and a second auxiliary electrical contact, where the first auxiliary electrical connection electrically connects the first auxiliary electrical contact to the top shield, and where the second auxiliary electrical connection electrically connects the second auxiliary electrical contact to the bottom shield.Type: ApplicationFiled: June 18, 2001Publication date: February 7, 2002Inventors: Kevin Richard Heim, Clifton H. Chang, Peter Thomas Weyandt, Patrick Joseph Ryan
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Patent number: 6331924Abstract: An MR head using an MR element as a magnetic detector and having head elements formed on a substrate is provided which comprises a capacitor connected in parallel to the MR element. The substrate is made of a conductive material to serve as one of electrodes forming the capacitor. Owing to this construction, the MR element of the MR head is hardly broken down due to an ESD or EOS.Type: GrantFiled: April 2, 1999Date of Patent: December 18, 2001Assignee: Sony CorporationInventor: Akio Takada
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Publication number: 20010043446Abstract: A system and method for providing a magnetoresistive head is disclosed. The magnetoresistive head includes a first shield, a second shield, a magnetoresistive element, a first gap, and a second gap. The first gap is for insulating the magnetoresistive element from the first shield. The second gap is for insulating the magnetoresistive element from the first shield. The method and system include providing a heat conduction path coupled to the first shield and to the second shield. Heat may be transferred from the first shield and from the second shield via the heat conduction path.Type: ApplicationFiled: February 16, 1999Publication date: November 22, 2001Inventors: IRMELA C. BARLOW, CHUNG F. LAM
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Patent number: 6301087Abstract: A disk drive comprises a magneto-resistive read head and an inductive write head for use with removable hard disk cartridges. A four-burst embedded servo is written and read to guide the servo-positioning of the magneto-resistive read head over data tracks recorded on the removable hard disk.Type: GrantFiled: July 14, 1994Date of Patent: October 9, 2001Assignee: Nomai S.A.Inventor: Anthony David Combe
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Patent number: 6288880Abstract: A magneto-resistive read head having a “parasitic shield” provides an alternative path for currents associated with sparkovers, thus preventing such currents from damaging the read head. The parasitic shield is provided in close proximity to a conventional magnetic shield. The electrical potential of parasitic shield is held essentially equal to the electrical potential of the sensor element. If charges accumulate on the conventional shield, current will flow to the parasitic shield at a lower potential than would be required for current to flow between the conventional shield and the sensor element. Alternatively, conductive spark gap devices are electrically coupled to sensor element leads and to each magnetic shield. Each spark gap device is brought within very close proximity of the substrate to provide an alternative path for charge that builds up between the sensor element and the substrate to be discharged.Type: GrantFiled: November 4, 1999Date of Patent: September 11, 2001Assignee: International Business Machines CorporationInventors: Timothy Scott Hughbanks, Neil Leslie Robertson, Steven Howard Voldman, Albert John Wallash
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Patent number: 6275361Abstract: Systems and methods for protecting a MR head against ESD are described. The MR head may be automatically and repeatedly shorted (and consequently disabled) whenever the MR head is not required to be operable (e.g., any time after final installation or during testing). The MR head may be coupled to a support assembly that is configured to connect to an actuator assembly. The support assembly includes a shorting mechanism that automatically shorts the MR head upon disconnection of the support assembly from the actuator assembly, regardless of the orientation of the support assembly, and automatically unshorts the MR head upon connection of the support assembly to the actuator assembly. In particular, the support assembly includes a deformable surface characterized by a relaxed state in which the MR head is shorted and a deformed state the MR head is unshorted, wherein the MR head may be repeatedly shorted and unshorted by repeatedly relaxing and deforming the deformable surface.Type: GrantFiled: May 13, 1999Date of Patent: August 14, 2001Assignee: Maxtor CorporationInventors: Al Wallash, Ferouh Goceman
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Patent number: 6267903Abstract: The method of manufacturing a magnetic head is capable of preventing element sections from being damaged by static electricity and which is capable of keeping prescribed characteristics of the magnetic head. The method of the present invention comprises the steps of: forming film layers on a surface of a substrate; etching the film layers to form into prescribed patterns; and forming an element section having prescribed characteristics, wherein a specific section of the substrate, in which the element section is formed, is enclosed by electric conductive film.Type: GrantFiled: December 11, 1998Date of Patent: July 31, 2001Assignee: Fujitsu LimitedInventor: Motoichi Watanuki
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Patent number: 6259573Abstract: A preamplifier circuit to improve the ESD immunity of magnetic recording devices having magnetoresistive (MR) sensors, without degrading the sensor's high-frequency characteristics. The preamplifier circuit is coupled to an MR sensor having one terminal grounded. The preamplifier circuit includes a varistor coupled between a power supply line and a ground terminal. If a high voltage, exceeding the varistor voltage, is applied to the chassis (ground), it is discharged through the varistor between the power supply voltage line and the ground terminal, instead of through the MR head or the arm electronics module. The present invention thereby protects the MR head and the arm electronics module from ESD damage.Type: GrantFiled: February 22, 1999Date of Patent: July 10, 2001Assignee: International Business Machines CorporationInventors: Kazushi Tsuwako, Yoshiro Amano, Takao Matsui, Tsuyoshi Miura
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Patent number: 6246553Abstract: An MR or GMR head is described which solves a head spiking problem with a charge clamp structure which provides a noninsulating electrical path from a conducting shield to an MR element lead to prevent charge buildup. Various embodiments of the charge clamp which are described include a center-tapped resistor which provides an electrical path from the S2 shield (and optionally the S1 shield) to both leads of the MR element to form a self-tracking clamp. Alternatively the resistance configurations described can be duplicated for each shield. A storage system using the invention connects the system's bias circuitry to apply a dc bias voltage on the MR elements leads which in turn are electrically connected to the shield.Type: GrantFiled: December 2, 1998Date of Patent: June 12, 2001Assignee: International Business Machines CorporationInventor: Robert G. Biskeborn
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Patent number: 6233127Abstract: The present invention is directed to a thin film device in which a function of electrostatic breakdown prevention can be enabled or disabled with ease and at which a member for electrostatic breakdown prevention can be externally provided with ease. The thin film device includes a thin film element, at least two lead conductors and a member for switching. The lead conductors, each connected to the thin film element at one end, are respectively connected to output terminals at the other ends. The member for switching, which is connected between the lead conductors performs a switching operation on energy supplied from the outside to prevent any electrostatic breakdown of the thin film element.Type: GrantFiled: April 5, 1999Date of Patent: May 15, 2001Assignee: TDK CorporationInventor: Koji Shimazawa
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Patent number: 6219206Abstract: In a magneto-resistive effect type head having provided between a lower shield layer and an upper shield layer an MR sensor with a magneto-resistive effect or a gigantic magneto-resistive effect; electrode layers electrically connected to the MR sensor; and lower and upper insulating layers mangetically and electrically isolating the MR sensor and the electrode layer from the shield layers, when the gap length is reduced and the lower and upper insulating layers are decreased in thickness, the insulating layers are more liable to a dielectric breakdown by static electricity produced in the manufacturing process of the magnetic head.Type: GrantFiled: August 26, 1999Date of Patent: April 17, 2001Assignee: Hitachi, Ltd.Inventors: Shiroyasu Odai, Matahiro Komuro
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Patent number: 6163443Abstract: An actuator assembly including an actuator arm, a suspension fixed to a front end portion of the actuator arm, and a head slider mounted on a front end portion of the suspension and having a magnetoresistive element. The suspension has a pair of first lead lines each of which has one end connected to the magnetoresistive element, and an easily removable short-circuit pattern for connecting the first lead lines with each other. The actuator assembly further includes a main FPC fixed at one end portion thereof to the actuator arm, and an interconnection FPC having a plurality of second lead lines for interconnecting the first lead lines and a wiring pattern of the main FPC. The interconnection FPC further has a plurality of ground lines for electrically connecting the second lead lines to the actuator arm. In using the actuator assembly in a magnetic disk drive, the short-circuit pattern is fused and each ground line is cut.Type: GrantFiled: September 22, 1998Date of Patent: December 19, 2000Assignee: Fujitsu LimitedInventors: Toshifumi Hatagami, Takayuki Bitoh
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Patent number: 6163437Abstract: A magnetic head with a spin valve effect MR element and a method of manufacturing the head. A plurality of spin valve effect MR elements on a substrate are formed, a plurality of pairs of lead conductors connected with the respective spin valve effect MR elements on the substrate are formed, and then a plurality of protection circuits of magnetization inversion connected between the respective pairs of lead conductors on the substrate are formed. Each of the protection circuits is constituted so as to turn on when it receives an energy with a level at which the pinned direction inversion in each of the spin valve effect MR elements occurs.Type: GrantFiled: March 20, 1998Date of Patent: December 19, 2000Assignee: TDK CorporationInventors: Kenji Inage, Toshiaki Maeda, Jun Shouji, Koichi Terunuma, Masanori Sakai
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Patent number: 6160688Abstract: To provide an MR composite head wherein damage of an MR element due to discharge of the static electricity is surely prevented with a simple configuration without degrading reproduction performance of the MR composite head, a first and a second magnetic shield layer (14 and 17), whereby the MR layer (20) is sandwiched, are designed to be grounded through a suspension (25). In an embodiment, a conductive member (24) is formed at an upper surface (11b) of the MR composite head (11) opposite to a facing surface (11a) facing to a magnetic disk (31), for electrically connecting the first and the second magnetic shield layer (14 and 17) to a slider (12) which is electrically connected to the suspension (25).Type: GrantFiled: December 14, 1998Date of Patent: December 12, 2000Assignee: NEC CorporationInventor: Toshiyuki Okumura