Magnecomp Corporation

3m Innovative Properties Company

Christopher G Dunn

Peter Hahn

Christopher Schreiber

Kuen Chee Ee

Nathan P Kreutter

Benjapa Tanampee

Keith Allan Vanderlee

Rui Yang

Jatuporn Nakarpha

Keither A Vanderlee

In a disk drive having a flexible circuit tail that is routed within a recess in the actuator arm, a dielectric spacer is added to the top of the tail in order to space the circuit traces within the tail further away from the electrically conductive actuator arm, and to make more repeatable that spacing. The added spacing reduces electrical coupling and thus increases the bandwidth of the circuit. The spacer can be in the form of a section of the same viscoelastic material that is used elsewhere as a vibration dampener on the suspension, the viscoelastic material being adhered to the tail before the tail is inserted within the recess. Alternatively, the spacer can be a thickened region of the flexible circuit covercoat in the area where the tail will reside within the recess.

Flexure assembly configured to reduce electrical coupling and maintain a high signal bandwidth

A multi-level piezoelectric actuator is manufactured using wafer level processing. Two PZT wafers are formed and separately metallized for electrodes. The metallization on the second wafer is patterned, and holes that will become electrical vias are formed in the second wafer. The wafers are then stacked and sintered, then the devices are poled as a group and then singulated to form nearly complete individual PZT actuators. Conductive epoxy is added into the holes at the product placement step in order to both adhere the actuator within its environment and to complete the electrical via thus completing the device. Alternatively: the first wafer is metallized; then the second wafer having holes therethrough but no metallization is stacked and sintered to the first wafer; and patterned metallization is applied to the second wafer to both form electrodes and to complete the vias. The devices are then poled as a group, and singulated.

Method of manufacturing a multi-layer PZT microactuator using wafer-level processing

Disk drive head stack assembly having height-controlled suspension circuit tail tack

A microactuator assembly is formed by depositing PZT material over electrode gaps, the electrode gaps being defined by the spaces between interleaved fingers of metal that define alternating plus and minus electrodes. The PZT material is hardened and poled. The PZT material may be deposited and poled either as isolated islands of PZT material across respective electrode gaps, or as a continuous sheet of PZT material with localized areas of that material being poled and then activated. The individual PZT elements are arranged such that successive PZT elements extend in the same direction as across the electrode gaps. The resulting microactuator assembly acts in the d33 direction of the PZT elements. The electrodes have raised or recessed features such as ribs or castellations, with the PZT material mating with those features, thus anchoring the PZT material to the electrodes.

Comb structure for a disk drive suspension piezoelectric microactuator operating in the D33 mode, and method of manufacturing the same

A piezoelectric actuator such as for a hard disk drive or other application has a restraining layer on its side that is opposite the side on which the PZT is mounted. The restraining layer is a stiff material. The restraining layer reduces bending of the PZT as mounted and hence increases effective stroke length, or reverses the sign of the bending which increases the effective stroke length of the PZT even further. For simplicity of construction and assembly to the suspension, the PZT actuator may be a multi-layer PZT with the top layer being unpoled or otherwise inactive PZT material, and having a wrap-around electrode so that the actuator can be mechanically and electrically bonded to the suspension or other environment using a single adhesive dispense and cure step.

Piezoelectric actuator with wrap-around electrode on inactive constraining layer

An electrical circuit for a disk drive suspension has a first signal trace above a grounded support layer which is typically stainless steel, and a second signal trace below the support layer, the two signal traces typically being opposite polarities of a differential signal pair. The support layer between the two signal traces is windowed, and the two traces are physically separated by a distance that equals the nominal thickness of the support layer plus the thicknesses of the top and bottom dielectric layers that separate the signal traces from the support layer. The physical separation combined with the windowing reduces the impedance and increases the bandwidth of the differential pair. The impedance can be controlled by the percentage of windowing in the support layer.

Suspension circuit trace employing stacked traces and windowed stainless steel layer

A PZT microactuator such as for a hard disk drive has a restraining layer on its side that is opposite the side on which the PZT is mounted. The restraining layer is a stiff material. The restraining layer reduces bending of the PZT as mounted and hence increases effective stroke length, or reverses the sign of the bending which increases the effective stroke length of the PZT even further. For simplicity of construction and assembly to the suspension, the PZT microactuator may be a multi-layer PZT with the top layer being unpoled or otherwise inactive PZT material, and having a wrap-around electrode so that the microactuator can be mechanically and electrically bonded to the suspension using a single adhesive dispense and cure step.

Suspension microactuator with wrap-around electrode on inactive constraining layer

A low impedance, low crosstalk disk drive suspension circuit has multiple traces carrying a first polarity of a differential signal, interleaved with multiple traces carrying the second polarity of a differential signal. Each pair of conductors consisting of a trace of the first polarity and a trace of the second polarity may cross over each other at multiple crossover points. The crossover connections may utilize a second layer of copper trace conductors over the first and main layer, or alternatively the crossover connections may utilize an isolated portion of the suspension substrate.

Low impedance, high bandwidth disk drive suspension circuit

An electrical interconnect from a suspension electrical circuit to a PZT microactuator motor includes copper plated onto a first side of a stainless steel support layer and gold plated onto a second and opposite side of the stainless steel support layer, with the gold plated stainless steel surface bonded to the PZT motor surface by conductive epoxy. The stainless steel may have a via etched into it to the copper surface before the gold plating step which then plates both the stainless steel and the copper with gold, so that the conductive epoxy is in physical and electrical contact with both the gold plated stainless steel and thus in electrical contact with the copper, and also in direct physical and electrical contact with the gold plated copper.

Electrical interconnect from disk drive suspension flexure to PZT motor

An electrical interconnect and a method of making an electrical interconnect in which a conductor has been substantially plated with a first protective metal shell, such as nickel, and a second outer metal shell, such as gold, before a covercoat has been applied. Such an electrical interconnect can be characterized as having an even-thickness outer shell on both its terminal pads and underneath the covercoat adjacent to the terminal pads, without overhangs or gaps near the bottom of the covercoat caused by surface etching during production.

Electrical interconnect with improved corrosion resistance for a disk drive head suspension

A method is presented for creating multilayer bond pads for bonding a disk drive suspension circuit to a read-write head slider. The multilayer bond pads eliminate the need for vias to transition signals between metallization layers within a suspension circuit. The method includes the steps of forming an aperture through an insulating material that has a metalized first side, depositing a second metal layer on the second side and within the aperture, the second metal layer forming an electrical contact with the first metal layer, selectively removing portions of the second metal layer within the aperture and corresponding adjacent portions of the first metal layer thereby dividing the second metal layer and respectively adjacent portions of the first metal layer into a plurality of electrically separated circuit bond pads, each bond pad including respective portions of the first metal layer and respectively adjacent portions of the second metal layer.

Multilayer bond pads for hard disk drive suspensions

A multi-layer circuit such as for a disk drive suspension has two regions: a supported region in which first and second stacked signal conductors are supported on a stainless steel support layer and an insulating layer, and an unsupported region having flying leads in which the flying leads are not supported below by the support layer. The two stacked signal conductors are formed by two separate plating operations, the two plating operations simultaneously creating the flying leads and the unsupported portions of the signal conductors, such that the flying leads have thicknesses that are the sum of the thicknesses of the individual conductors. Crossbars and vias allow the different plating layers to be connected together. This construction allows the individual conductors to be relatively thin and flexible for good electrical and mechanical performance, while creating relatively thick flying leads that are resistant to handling damage.

High strength flying leads for multi-layer flexure designs

A disk drive suspension circuit has copper signal conductors connected by vias through an insulative layer to respective stainless steel flying leads. The stainless steel flying leads are activated and plated with one or more metals, with a final layer over the flying lead being a layer such as gold, suitable for bonding to form bond pads. The gold bond pads may be attached using thermosonic welding, solder ball bonding, or other suitable methods to an electrical component such as wires or a the disk drive's pre-amp circuit.

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Austin, TX, United States of America

Christopher G Dunn