Electrostatic Discharge (esd) Protection Patents (Class 360/323)
  • Patent number: 7239488
    Abstract: According to an embodiment of the present invention, a slider design is presented that provides improved protection for the head/sensor of the slider. In one embodiment, the design of the slider is such that ESD protection is provided during the slider wafer process, the “back-end” processes (e.g., when the completed slider/head is incorporated into an HGA), and during operation in a disk drive or the like. In this embodiment, a conductive film is provided that surrounds the insulating-material slider substrate. The conductive film provides a grounding path during the wafer fabrication processes. This conductive layer may be further patterned during head fabrication to provide a ground path for back-end fabrication processes. A conductive stripe may be added for discharging debris in the slider-to-disk interface.
    Type: Grant
    Filed: March 9, 2004
    Date of Patent: July 3, 2007
    Assignee: SAE Magnetics (H.K.), Ltd.
    Inventors: Li-Yan Zhu, Kazumasa Yasuda, Cheng Yih Liu, Winston Jose
  • Patent number: 7236334
    Abstract: A method for shorting, unshorting, and reshorting an electronic component such as an MR sensor provides a repeatable ESD protection scheme. A conductive line of an electrically conductive first shorting material is created between electrical leads operatively coupled to an electronic component for creating a short therebetween. The short is severed using a laser. The short is recreated by applying a second shorting material, which may or may not be the same as the first shorting material.
    Type: Grant
    Filed: August 31, 2004
    Date of Patent: June 26, 2007
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Meng Ding, Surya Narayan Pattanaik, Chie Ching Poon, Neil Leslie Robertson
  • Patent number: 7223922
    Abstract: A cable having an electrostatic discharge (ESD) dissipative coating. The cable includes a lead and an ESD dissipative coating operatively coupled to the lead. Other layers such as adhesives and insulating layers can be provided. The ESD dissipative coating can also function as the insulator for the lead.
    Type: Grant
    Filed: July 28, 2004
    Date of Patent: May 29, 2007
    Assignee: International Business Machines Corporation
    Inventors: William Thomas Bandy, IV, Icko Eric Timothy Iben, Peter John Golcher, John Bradley Kriehn, Ho-Yiu Lam, Jeffrey Serrell Snyder, Larry LeeRoy Tretter, George G. Zamora
  • Patent number: 7199992
    Abstract: A system and associated method are disclosed for protecting a magnetoresistive (MR) head from damage caused by electrostatic discharge. Included is a protective member having a conductive surface for being removably positioned on a MR connector cable such that the conductive surface remains in electrical communication with contacts of the MR connector cable. Thus, the contacts are shorted to protect a MR head coupled to the MR connector cable from damage caused by electrostatic discharge. Further included is a clamp releasably coupled to the protective member for maintaining the conductive surface of the protective member in electrical communication with the contacts of the MR connector cable to facilitate the shorting of the contacts, thus ensuring the protection of the MR head coupled to the MR connector cable from the damage caused by the electrostatic discharge.
    Type: Grant
    Filed: April 21, 2003
    Date of Patent: April 3, 2007
    Assignee: International Business Machines Corporation
    Inventors: William M. Dyer, Hoodin Hamidi
  • Patent number: 7190556
    Abstract: A method for preventing electrostatic discharge (ESD) damage in the head-suspension assembly (HSA) construction process. The method teaches the formation of a novel GMR magnetic recording head on a conductive slider substrate, the GMR head being electrically connected to the substrate and its conducting leads having balanced resistances between the leads and the substrate. By establishing an electrical connection between the GMR head and the slider substrate, the entire HSA can be grounded during its construction. By also grounding any nearby conducting elements that could inadvertently contact the HSA or its parts, no accumulated tribocharges can discharge through the sensitive GMR sensor element.
    Type: Grant
    Filed: February 28, 2005
    Date of Patent: March 13, 2007
    Assignee: Headway Technologies, Inc,
    Inventor: Li-Yan Zhu
  • Patent number: 7167331
    Abstract: A magnetic storage system includes a read element including a tunneling giant magneto-resistive (TGMR) sensor. A shunting device includes a control terminal and first and second terminals that communicate with respective first and second terminals of the read element. The shunting device shorts said first and second terminals when said control terminal is not powered to protect the read element from electrostatic discharge. A first voltage limiting circuit limits voltage that is input to first terminals of said shunting device and said read element. Said first voltage limiting circuit includes first and second diodes. An anode of said first diode and a cathode of said second diode communicate with said first terminal of said read element and said first terminal of said shunting device and a cathode of said first diode and an anode of said second diode communicate.
    Type: Grant
    Filed: June 25, 2004
    Date of Patent: January 23, 2007
    Assignee: Marvell International Ltd.
    Inventor: Pantas Sutardja
  • Patent number: 7161772
    Abstract: A removable device which is used during manufacturing for ESD/EOD protection and removed when the head is mounted in a drive. The device consists of crossed diodes which are mounted in the device and will connect to the readers. Each reader has two or more crossed diodes detachably coupled to its leads. The diodes are mounted on a device which is removable at the end of manufacturing assembly and the device can be reused. The device limits the voltage across a reader to the voltage limit of the number of diodes connected in series. Crossed diodes are connected in parallel with the electrical device to be protected to protect against random current spikes in either direction through the device in question. The device has leads which can be connected to an external device to measure the reader resistance or other electrical properties.
    Type: Grant
    Filed: November 19, 2003
    Date of Patent: January 9, 2007
    Assignee: International Business Machines Corporation
    Inventor: Icko E. T. Iben
  • Patent number: 7145187
    Abstract: In a multiple input ESD protection structure, the inputs are isolated from the substrate by highly doped regions of opposite polarity to the input regions. Dual polarity is achieved by providing a symmetrical structure with n+ and p+ regions forming each dual polarity input. The inputs are formed in a p-well which, in turn, is formed in a n-well. Each dual polarity input is isolated by a PBL under the p-well, and a NISO underneath the n-well. An isolation ring separates and surrounds the inputs. The isolation ring comprises a p+ ring or a p+ region, n+ region, and p+ region formed into adjacent rings.
    Type: Grant
    Filed: December 12, 2003
    Date of Patent: December 5, 2006
    Assignee: National Semiconductor Corporation
    Inventors: Vladislav Vashchenko, Peter J. Hopper, Philipp Lindorfer
  • Patent number: 7142398
    Abstract: A magnetoresistive head assembly of the present invention includes a magnetoresistive sensor and an electrostatic discharge and electrical overstress protection circuit. The magnetoresistive sensor 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: Grant
    Filed: August 1, 2002
    Date of Patent: November 28, 2006
    Assignee: Seagate Technology LLC
    Inventors: Eric L. Granstrom, Ned Tabat
  • Patent number: 7119995
    Abstract: A transducing head includes a sensor element having a plurality of terminal pads and a shunt electrically connected with the sensor element in parallel for protecting the sensor element from electrical damage during fabrication of the transducing head. The shunt includes one or more fuses, where the shunt configured to be repeatedly tested around during fabrication to allow testing of the sensor element. The shunt is structured to be permanently electrically removable prior to operation of the transducing head by directing a shunt removal current through the shunt which effectively creates an open circuit in the shunt without causing a damaging current to flow in the sensor element. In another embodiment, the transducing head includes a shunt electrically connected with the sensor element in parallel.
    Type: Grant
    Filed: January 22, 2004
    Date of Patent: October 10, 2006
    Assignee: Seagate Technology LLC
    Inventors: Eric L. Granstrom, James G. Wessel
  • Patent number: 7081367
    Abstract: A manufacturing method of a thin-film magnetic head with an MR element or a manufacturing method of an HGA with the head includes a step of forming a plurality of MR elements on a substrate or wafer, a step of forming a plurality of pairs of connection pads, each pair of connection pads being electrically connected across each MR element, a step of forming a plurality of thin-film short-circuit patterns on a surface of the wafer, each short-circuit electrically short-circuiting between each pair of connection pads, and a step of thereafter breaking each short-circuit pattern by laser radiation during a predetermined manufacturing process of the magnetic head.
    Type: Grant
    Filed: March 31, 2004
    Date of Patent: July 25, 2006
    Assignee: SAE Magnetics (H.K.) Ltd.
    Inventor: Masashi Shiraishi
  • Patent number: 7046488
    Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk. The head comprising a first head terminal and a second head terminal. The disk drive further comprises an electrostatic discharge (ESD) protection circuit comprising a first depletion mode metal oxide semiconductor field effect transistor (MOSFET) comprising a gate terminal and a first and second transistor terminals. The first transistor terminal of the first depletion mode MOSFET is coupled to the first head terminal, and the second transistor terminal of the first depletion mode MOSFET is coupled to the second head terminal. The gate terminal is biased to turn on the first depletion mode MOSFET while the disk drive is powered down, thereby shorting the first and second head terminals to protect the head from ESD.
    Type: Grant
    Filed: January 7, 2005
    Date of Patent: May 16, 2006
    Assignee: Western Digital Technologies, Inc.
    Inventor: Dennis W. Hogg
  • Patent number: 7035050
    Abstract: A disk drive suspension interconnect of a flexible conductive laminate with an electrically insulative layer and a pair of trace conductors supported thereon is shunted by having an insulative layer first portion supporting the trace conductors oppose a deflectable layer second portion free of the trace conductors and disposed beyond the first portion and carrying a shunt structure for connecting in parallel the trace conductors. The shunt structure conductive material is arranged on the second portion to contact in shunting relation the trace conductor pair in the deflected condition of the second portion and further has adhesive arranged thereon to secure the first portion in place.
    Type: Grant
    Filed: July 2, 2002
    Date of Patent: April 25, 2006
    Assignee: Magnecomp Corporation
    Inventor: Sivadasan Kulangara
  • Patent number: 7009820
    Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk. The head comprising a first head terminal and a second head terminal. The disk drive further comprises an electrostatic discharge (ESD) protection circuit comprising a first depletion mode metal oxide semiconductor field effect transistor (MOSFET) and a second depletion mode MOSFET. A first transistor terminal of the depletion mode MOSFETs are coupled to respective head terminals, and a second transistor terminal of the depletion mode MOSFETs are coupled to ground. The gate terminals of the first and second depletion mode MOSFETs are biased to turn on the depletion mode MOSFETs while the disk drive is powered down, thereby grounding the first and second head terminals to protect the head from ESD.
    Type: Grant
    Filed: December 24, 2002
    Date of Patent: March 7, 2006
    Assignee: Western Digital Technologies, Inc.
    Inventor: Dennis W. Hogg
  • Patent number: 7009819
    Abstract: A head substrate and a protective substrate are formed of an electrostatic-discharge resistant conductive material having an electrical resistivity of 102 to 1010 ?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: Grant
    Filed: October 9, 2002
    Date of Patent: March 7, 2006
    Assignee: Sony Corporation
    Inventors: Yutaka Soda, Yoshimi Takahashi, Susumu Sato, Seiji Onoe
  • Patent number: 6995958
    Abstract: A method for preventing electrostatic discharge (ESD) damage in the head-suspension assembly (HSA) construction process. The method teaches the formation of a novel GMR magnetic recording head on a conductive slider substrate, the GMR head being electrically connected to the substrate and its conducting leads having balanced resistances between the leads and the substrate. By establishing an electrical connection between the GMR head and the slider substrate, the entire HSA can be grounded during its construction. By also grounding any nearby conducting elements that could inadvertently contact the HSA or its parts, no accumulated tribocharges can discharge through the sensitive GMR sensor element.
    Type: Grant
    Filed: February 28, 2005
    Date of Patent: February 7, 2006
    Assignee: Headway Technologies, Inc.
    Inventor: Li-Yan Zhu
  • Patent number: 6985336
    Abstract: A head substrate and a protective substrate are formed of an electrostatic-discharge resistant conductive material having an electrical resistivity of 102 to 1010 ?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: Grant
    Filed: April 28, 2005
    Date of Patent: January 10, 2006
    Assignee: Sony Corporation
    Inventors: Yutaka Soda, Yoshimi Takahashi, Susumu Sato, Seiji Onoe
  • Patent number: 6972933
    Abstract: A head suspension assembly includes a magnetic head slider with at least one thin-film magnetic head element, a support member for supporting the magnetic head slider at a top end portion thereof, a drive circuit electrically connected to the at least one thin-film magnetic head element, and at least two diode elements connected toward one direction in parallel with terminals which are connected across the at least one thin-film magnetic head element. Each of the diode elements has a turn-on voltage higher than the maximum output voltage of the at least one thin-film magnetic head element.
    Type: Grant
    Filed: October 18, 1999
    Date of Patent: December 6, 2005
    Assignee: TDK Corporation
    Inventors: Takeshi Wada, Kenji Inage, Masashi Shiraishi, Haruyuki Morita
  • Patent number: 6972930
    Abstract: A Head Gimbal Assembly (HGA) for use in a disk drive and comprising an ESD-protected slider comprising a head formed on a slider substrate. The slider may comprise an electrical-isolation circuit; an electrically-resistive path between head input connections and the slider; or both isolation circuits and resistive paths for reducing electrostatic charge on the slider while remaining connected during disk drive operations.
    Type: Grant
    Filed: February 28, 2003
    Date of Patent: December 6, 2005
    Assignee: Western Digital Technologies, Inc.
    Inventors: Kathy X. Tang, Jai N. Subrahmanyam, Rahmat Karimi
  • Patent number: 6944937
    Abstract: The present invention provides a method of manufacturing a magnetoresistive read head which reduces electrostatic discharge and allows measurement of gap resistances in the head.
    Type: Grant
    Filed: June 30, 2003
    Date of Patent: September 20, 2005
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Richard Hsiao, James D. Jarratt, Emo Hilbrand Klaassen, Ian Robson McFadyen, Timothy J. Moran
  • Patent number: 6927951
    Abstract: 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: Grant
    Filed: April 2, 2002
    Date of Patent: August 9, 2005
    Assignee: Seagate Technology LLC
    Inventors: Marsha Huha, Kevin Schulz, Werner Weidemann
  • Patent number: 6914758
    Abstract: A magnetoresistive head apparatus includes first and second readers. The first reader is a magnetoresistive reader. The second reader provides electrostatic discharge protection for the first magnetoresistive reader. The second reader can be a second magnetoresistive reader having substantially the same film structure as the first reader. The second reader can also include a phase change thin film, which has high and low resistance states that are changeable using a laser.
    Type: Grant
    Filed: June 30, 2003
    Date of Patent: July 5, 2005
    Assignee: Seagate Technology LLC
    Inventors: Patrick Joseph Ryan, Song Sheng Xue
  • Patent number: 6902099
    Abstract: 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: Grant
    Filed: April 10, 2002
    Date of Patent: June 7, 2005
    Assignee: Alps Electric Co., Ltd.
    Inventors: Michiharu Motonishi, Michiaki Moroe
  • Patent number: 6894879
    Abstract: 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: Grant
    Filed: December 17, 2001
    Date of Patent: May 17, 2005
    Assignee: Seagate Technology LLC
    Inventors: Frank William Schadewald, Jr., Arnold Warren Johansen
  • Patent number: 6891702
    Abstract: A disk drive includes a disk having a recording surface, a head stack assembly that includes a body portion, an actuator arm cantilevered from the body portion and a head gimbal assembly supported at the actuator arm. The head gimbal assembly includes a suspension having a first end and a second end, the first end being attached to the actuator arm, a slider coupled to the second end of the suspension, the slider comprising a transducer for reading from and writing to the recording surface. A gimbal is coupled to the second end of the suspension and to the slider. An array of diodes is attached to the suspension to protect the transducer from electrostatic discharge or electrical overstress events.
    Type: Grant
    Filed: October 31, 2002
    Date of Patent: May 10, 2005
    Assignee: Western Digital Technologies, Inc.
    Inventor: Kathy X. Tang
  • Patent number: 6870706
    Abstract: A method for preventing electrostatic discharge (ESD) damage in the head-suspension assembly (HSA) construction process. The method teaches the formation of a novel GMR magnetic recording head on a conductive slider substrate, the GMR head being electrically connected to the substrate and its conducting leads having balanced resistances between the leads and the substrate. By establishing an electrical connection between the GMR head and the slider substrate, the entire HSA can be grounded during its construction. By also grounding any nearby conducting elements that could inadvertently contact the HSA or its parts, no accumulated tribocharges can discharge through the sensitive GMR sensor element.
    Type: Grant
    Filed: August 7, 2002
    Date of Patent: March 22, 2005
    Assignee: Headway Technologies, Inc.
    Inventor: Li-Yan Zhu
  • Publication number: 20040264065
    Abstract: A circuit includes an element that can damaged by a potential over 400 mV. The element conducts with an element conductance over an element operating voltage range under 400 mV at element leads. The circuit also includes a shunt protective device connected to at least one of the element leads. The shunt protective device conducts with a shunt conductance above 400 mV that is greater than the element conductance. The shunt protective device conducts with a shunt conductance over the element operating voltage range that is less than the element conductance.
    Type: Application
    Filed: January 21, 2004
    Publication date: December 30, 2004
    Inventors: Stefan A. Ionescu, Zhe Shen
  • Patent number: 6836391
    Abstract: 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: Grant
    Filed: October 29, 2001
    Date of Patent: December 28, 2004
    Assignee: Fujitsu Limited
    Inventor: Eiichi Kanda
  • Patent number: 6813122
    Abstract: A magnetic recording head system is protected against electrostatic discharge (ESD) and electrical overstress (EOS). The system includes a transducing read element and a drive circuit for connection to operate the transducing read element. A microelectromechanical switch has an input to receive an electrical control signal that selectively switches between a first state for protecting the transducing read element and a second state for operating the transducing read element.
    Type: Grant
    Filed: January 21, 2003
    Date of Patent: November 2, 2004
    Assignee: Seagate Technology LLC
    Inventor: Eric Leroy Granstrom
  • Patent number: 6801402
    Abstract: A Head Gimbal Assembly (HGA) for use in a disk drive and further includes a head having a read element and a write element; and a Trace Gimbal Assembly (TGA) attached to the head. The TGA includes a conductor array having a first end connected to the read element and the write element and a distal end for connecting the read element and the write element to a signal processing circuit, a conductive substrate supporting the head and the conductor array and a dielectric layer disposed between the conductor array and the conductive substrate. The TGA further includes a shunt connected at the distal end for shunting the read element; and an anti-static coating, covering a substantial portion of the conductor array for neutralizing electrostatic charge accumulation on the conductor array.
    Type: Grant
    Filed: October 31, 2002
    Date of Patent: October 5, 2004
    Assignee: Western Digital Technologies, Inc.
    Inventors: Jai N. Subrahmanyam, Darrell D. Palmer, Jack M. Chue
  • Patent number: 6795278
    Abstract: 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: Grant
    Filed: March 28, 2002
    Date of Patent: September 21, 2004
    Assignee: International Business Machines Corporation
    Inventors: James Devereaux Jarrett, Richard Hsiao, Ciaran Avram Fox, Edward Hin Pong Lee, Thomas Robert Albrecht
  • Patent number: 6760199
    Abstract: A magnetic head assembly with an air bearing surface (ABS) layer over a double-shielded magnetoresistive (MR) sensor and a write gap formed between two spaced magnetic pole tips, with an optional write-gap shield disposed so that one magnetic pole tip is disposed between the write-gap shield and the other magnetic pole tip. At least one of the MR element shields is electrically connected to one of the MR signal lead conductors (preferably the one having the most positive potential) and the one magnetic pole tip (and/or the optional write-gap shield) is coupled to the clamped MR element shield with an electrical conductor. For multi-track read/write arrays, the connection between adjacent reader shield and writer pole and/or shield is provided independently for each read/write pair in the array, thereby equalizing the voltage environments to reduce variations in the chemical/mechanical erosion of the read and write head ABS layers.
    Type: Grant
    Filed: July 23, 2001
    Date of Patent: July 6, 2004
    Assignee: International Business Machines Corporation
    Inventor: Robert Glenn Biskeborn
  • Publication number: 20040090715
    Abstract: 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: Application
    Filed: June 30, 2003
    Publication date: May 13, 2004
    Applicant: Hitachi Global Storage Technologies
    Inventors: Richard Hsiao, James D. Jarratt, Emo Hilbrand Klaassen, Ian Robson McFadyen, Timothy J. Moran
  • Patent number: 6731476
    Abstract: 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: Grant
    Filed: July 31, 2000
    Date of Patent: May 4, 2004
    Assignee: Alps Electric Co., Ltd.
    Inventors: Michiharu Motonishi, Michiaki Moroe
  • Patent number: 6728082
    Abstract: 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: Grant
    Filed: April 2, 2001
    Date of Patent: April 27, 2004
    Assignee: Seagate Technology LLC
    Inventors: Ned Tabat, Paul E. Kupinski
  • Publication number: 20040075955
    Abstract: A magnetoresistive head apparatus includes first and second readers. The first reader is a magnetoresistive reader. The second reader provides electrostatic discharge protection for the first magnetoresistive reader. The second reader can be a second magnetoresistive reader having substantially the same film structure as the first reader. The second reader can also include a phase change thin film, which has high and low resistance states that are changeable using a laser.
    Type: Application
    Filed: June 30, 2003
    Publication date: April 22, 2004
    Applicant: Seagate Technology LLC
    Inventors: Patrick Joseph Ryan, Song Sheng Xue
  • Patent number: 6721140
    Abstract: A read head includes: an MR element that detects a magnetic field; a pair of electrode layers for feeding a sense current to the MR element; and a bottom shield layer and a top shield layer that sandwich and shield the MR element and the electrode layers; a bottom insulating layer disposed between the MR element/the electrode layers and the bottom shield layer; a top insulating layer disposed between the MR element/the electrode layers and the top shield layer; a bottom semiconductor layer that is made up of a single layer and disposed between the electrode layers and the bottom shield layer, for connecting the electrode layers and the bottom shield layer; and a top semiconductor layer that is made up of a single layer and disposed between the electrode layers and the top shield layer, for connecting the electrode layers and the top shield layer.
    Type: Grant
    Filed: November 15, 2001
    Date of Patent: April 13, 2004
    Assignee: TDK Corporation
    Inventors: Tohru Inoue, Shigeki Tanemura, Koichi Terunuma
  • Patent number: 6717068
    Abstract: 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: Grant
    Filed: October 2, 2002
    Date of Patent: April 6, 2004
    Assignee: Alps Electric Co., Ltd.
    Inventors: Michiharu Motonishi, Michiaki Moroe
  • Patent number: 6710983
    Abstract: A magnetic head includes a GMR read head that is protected from electrostatic discharge (ESD) on a slider by a silicon germanium (SiGe) integrated circuit device. In a preferred embodiment the SiGe circuit device includes one or more silicon germanium heterojunction bipolar transistors (SiGe HBT) or silicon germanium carbon heterojunction bipolar transistors (SiGeC HBT) that is electrically connected across the electrical leads of the GMR read head. Particular electrical connection configurations with the SiGe circuit devices include diodic modes, npn modes, series cascade modes and two stage ESD network configurations. The silicon chip may be sandwiched between the slider body and the read/write head or the read/write head may be sandwiched between the slider body and the silicon chip.
    Type: Grant
    Filed: May 10, 2002
    Date of Patent: March 23, 2004
    Assignee: International Business Machines Corporation
    Inventor: Steven Howard Voldman
  • Patent number: 6704173
    Abstract: A method and system for providing a suspension assembly for protecting a magnetoresistive (MR) head from electrostatic discharge damage is disclosed. The MR head includes an MR sensor having a first end and a second end. The method and system include providing a first lead and a second lead and providing an insulating film substantially supporting a first portion of the first lead and a second portion of the second lead. The MR head is coupled with the suspension assembly. The first and second ends of the MR sensor are coupled with the first and second leads, respectively. The method and system include providing a conductive strip coupled with the insulating film. In one aspect, the method and system include providing at least one diode electrically coupling the first lead and the second lead. In another aspect, the method and system also include electrically coupling first lead with the conductive strip.
    Type: Grant
    Filed: August 16, 2000
    Date of Patent: March 9, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Chung Fai Lam, Gary Lloyd Crown, Seila Chao Chim
  • Patent number: 6704174
    Abstract: A head substrate and a projection substrate of a head drum comprise a conductive material having a resistance of 1×1010&OHgr; or less and are connected to a metal base so as to be at the ground potential via the metal base and a rotating drum. These antistatic treatments allow static electricity charged on a magnetic tape to be discharged to the head substrate and the protection substrate without flowing to a magneto-resistive (MR) element, thereby preventing the electrostatic discharge breakdown of the MR element.
    Type: Grant
    Filed: December 13, 2001
    Date of Patent: March 9, 2004
    Assignee: Sony Corporation
    Inventors: Yutaka Soda, Nobuyuki Nagai, Katsuhiro Kasuga, Hiroshi Meguro, Tadashi Ozue
  • Patent number: 6687097
    Abstract: The present invention provides an ESD and EOS protection method and apparatus that can be easily implemented in existing disk drive designs and manufacturing process. One apparatus embodiment includes a first conductive member electrically connected to a first terminal of a magnetic head element; a second conductive member electrically connected to a first second terminal of the magnetic head element; and a variable conductive member, such as a variably conductive member. One method embodiment includes operably connecting a first conductive member to a first terminal of a magnetic head element; operably connecting a second conductive member to a second terminal of the magnetic head element; and operably connecting a variably conductive member, such as a variably conductive polymer, to the first conductive member and to the second conductive member.
    Type: Grant
    Filed: March 22, 2000
    Date of Patent: February 3, 2004
    Assignee: Pemstar, Inc.
    Inventors: Nathaniel C. Anderson, Robert D. Ahmann
  • Publication number: 20040017640
    Abstract: 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: Application
    Filed: February 2, 2001
    Publication date: January 29, 2004
    Inventors: Timothy Scott Hughbanks, Neil Leslie Robertson, Steven Howard Voldman, Albert John Wallash
  • Patent number: 6678127
    Abstract: 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: Grant
    Filed: January 2, 2001
    Date of Patent: January 13, 2004
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Richard Hsiao, James D. Jarratt, Emo Hilbrand Klaassen, Ian Robson McFadyen, Timothy J. Moran
  • Publication number: 20040004792
    Abstract: A magnetic sensing element is provided, in which magnetization of a free magnetic layer is likely to fluctuate when the track width is further reduced, and thereby, the magnetic field detection sensitivity can be improved. A second free magnetic layer having a dimension W2 in the track-width direction is laminated on a first free magnetic layer having a dimension W1 in the track-width direction while the dimension W2 is larger than the dimension W1. The film thickness ta of the free magnetic layer in the track-width region A is made larger than the film thickness tb of the free magnetic layer in both side regions B and B. Consequently, the magnetic flux density in the track-width region A of the free magnetic layer resulting from the static magnetic fields generated from both the side regions B and B of the free magnetic layer can be reduced, a dead zone which occurs in the track-width region A of the free magnetic layer can be reduced, and therefore, the magnetic field detection sensitivity is improved.
    Type: Application
    Filed: June 24, 2003
    Publication date: January 8, 2004
    Applicant: ALPS ELECTRIC CO., LTD.
    Inventors: Naoya Hasegawa, Eiji Umetsu
  • Patent number: 6671137
    Abstract: 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: Grant
    Filed: September 20, 2001
    Date of Patent: December 30, 2003
    Assignee: Mitsumi Electric Co., Ltd.
    Inventors: Satoshi Ajiki, Koichi Hosoya
  • Patent number: 6667860
    Abstract: This invention discloses a circuit including a magnetoresistive sensor and a tunnel junction device coupled to the MR sensor to dissipate the energy associated with an electrical signal exceeding operational voltages for the sensor. The tunnel junction can include a first conducting layer, a second conducting layer, and a barrier material positioned between the first and the second conducting layer. The barrier material can be positioned so that the first conducting layer and the second conducting layer do not make contact. The MR sensor can be connected in parallel to the first and second conducting layer. The tunnel junction can be made of a material with a resistance more than the MR sensor's resistance at operational voltages and a resistance below the MR sensor's resistance at larger voltages.
    Type: Grant
    Filed: October 5, 2000
    Date of Patent: December 23, 2003
    Assignee: Seagate Technology LLC
    Inventors: Eric Leroy Granstrom, Ned Tabat
  • Patent number: 6657827
    Abstract: A head includes a head chip, having first and second external connection electrodes, for reading a signal from a storage medium and writing a signal on the storage medium, a substrate having the head chip mounted thereon, a hot-side conductor path and a ground-side conductor path each formed on the surface of the substrate and electrically connected to the corresponding external connection electrodes of the head chip, and a chip varistor, mounted on the substrate, having first, second, and third terminal electrodes, the third terminal electrode being connected to the ground. In the head, the hot-side conductor path is divided, and the corresponding conductor parts of ends of the divided hot-side conductor paths are electrically connected to the first and the second terminal electrodes, and the ground-side conductor path is electrically connected to the third terminal electrode of the chip varistor.
    Type: Grant
    Filed: September 25, 2000
    Date of Patent: December 2, 2003
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Mitsumasa Fukuda, Yukio Sakamoto, Jun Kojima
  • Patent number: 6650511
    Abstract: 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: Grant
    Filed: February 11, 2002
    Date of Patent: November 18, 2003
    Assignee: International Business Machines Corporation
    Inventors: Richard Hsiao, James Devereaux Jarratt, Chie Ching Poon
  • Publication number: 20030210501
    Abstract: A magnetic head includes a GMR read head that is protected from electrostatic discharge (ESD) on a slider by a silicon germanium (SiGe) integrated circuit device. In a preferred embodiment the SiGe circuit device includes one or more silicon germanium heterojunction bipolar transistors (SiGe HBT) or silicon germanium carbon heterojunction bipolar transistors (SiGeC HBT) that is electrically connected across the electrical leads of the GMR read head. Particular electrical connection configurations with the SiGe circuit devices include diodic modes, npn modes, series cascade modes and two stage ESD network configurations. The silicon chip may be sandwiched between the slider body and the read/write head or the read/write head may be sandwiched between the slider body and the silicon chip.
    Type: Application
    Filed: May 10, 2002
    Publication date: November 13, 2003
    Inventor: Steven Howard Voldman