Method and mechanism of PZT micro-actuator attachment for the hard disk driver arm

A fixture with a shaped molding may hold a first micro-actuator part and a second micro-actuator part in place for coupling while maintaining the structure of the first micro-actuator part. The first micro-actuator part and the second micro-actuator part may be a frame or a strip of piezoelectric material. A vacuum nozzle system embedded in the fixture may hold the first micro-actuator part in place. A mobile vacuum nozzle system may hold the second micro-actuator in place and positions the second micro-actuator part relative to the first micro-actuator part. A camera system may monitor the process. A dispense may apply epoxy between the first and second micro-actuator part. An ultraviolet source may provide ultraviolet radiation for curing.

BACKGROUND INFORMATION

The present invention relates to magnetic hard disk drives. More specifically, the present invention relates to a method of assembling micro-actuators.

In the art today, different methods are utilized to improve recording density of hard disk drives.FIG. 1provides an illustration of a typical disk drive. The typical disk drive has a head gimbal assembly (HGA) configured to read from and write to a magnetic hard disk101. The HGA and the magnetic hard disk101are mounted to the base102of a main board103. The disk101is rotated relative to the base102by a spindle motor104. The HGA typically includes an actuator arm105and a load beam106. The HGA supports and positions a magnetic read/write slider107above the magnetic hard disk101. The HGA is rotated relative to the base102along the axis of a bearing assembly108by a voice coil motor109. A relay flexible printed circuit110connects a board unit111to the magnetic read/write slider107.

FIGS. 2a–dprovide an illustration of two embodiments of a piezoelectric micro-actuator.FIG. 2aillustrates a micro-actuator with a U-shaped ceramic frame configuration201. The frame201may be Zirconia. The frame201may have two arms202opposite a base203. A slider204may be held by the two arms202at the end opposite the base203. A strip of piezoelectric material205may be attached to each arm202.FIG. 2billustrates the micro-actuator as attached to an actuator suspension206. The micro-actuator may be coupled to a suspension tongue207. Traces208, coupled along the suspension206, apply a voltage to the strips of piezoelectric material205. These voltages may cause the strips205to contract and expand, moving the placement of the slider204.

FIG. 2cillustrates an alternate version of the micro-actuator. In this embodiment, a metallic frame209has a base210with two arms211perpendicular to the plane of the base210. A slider support212may hold the slider between the two arms211. A strip of piezoelectric material213is coupled to each arm211. The micro-actuator may then be attached to the head suspension206in the same manner as the ceramic micro-actuator, as shown inFIG. 2d.

One embodiment of a method of manufacturing the metallic frame209is shown inFIGS. 3a–d. The frame209may be stainless steel, such as SUS304. As shown inFIG. 3a, the two arms211of the metallic frame209may be formed using vertical forming by machine or laser. A hole301may be formed on the slider support212to facilitate the slider204mounting. The support connections302and the base connections303may be narrowed to improve resonance. The two strips of piezoelectric material213may each have at least one contact pad304attached that allows the strips213to be electrically coupled to a control circuit. As shown inFIG. 3b, the strips213may be coupled to the arms211of the metallic frame209. As shown inFIG. 3c, the slider204may be coupled to the slider support212. The slider204may be coupled using epoxy or some other kind of adhesive. The epoxy may be cured using the hole301in the slider support212. As shown inFIG. 3d, the micro-actuator may then be attached to the suspension tongue207.

FIGS. 4a–bprovides an illustration in a pair of charts of the effect of adhesive thickness on stroke and resonance.FIG. 4acompares the stroke in micrometers to the adhesive thickness in millimeters. In this example, stroke pertains to the amount of deflection of the slider caused by the micro-actuator.FIG. 4bcompares the resonance frequency of the micro-actuator in kilohertz to the adhesive thickness in millimeters. Due to the small size of the micro-actuators and the fragile nature of the piezoelectric material, stress fractures and distortions remain problems.

DETAILED DESCRIPTION

A fixture with a shaped molding may hold a first micro-actuator part and a second micro-actuator part in place for coupling while maintaining the structure of the first micro-actuator part. The first micro-actuator part and the second micro-actuator part may be a frame or a strip of piezoelectric material. A vacuum nozzle system embedded in the fixture may hold the first micro-actuator part in place. A mobile vacuum nozzle system may hold the second micro-actuator in place and positions the second micro-actuator part relative to the first micro-actuator part. A camera system may monitor the process. A dispenser may apply epoxy between the first and second micro-actuator part. An ultraviolet source may provide ultraviolet radiation for curing.

FIGS. 5a–eillustrate one embodiment of a method for attaching the strips of piezoelectric material213to the metallic frame209. As shown inFIG. 5a, the metallic frame209may be placed on a fixture501to maintain the structure of the metallic frame209while the strips of piezoelectric material213are added. The fixture501may have a shaped indentation502to match the exterior of the metallic frame209. Alternately, the fixture501may have a shaped protrusion that matches the interior of the metallic frame209. A vacuum nozzle503embedded within the fixture501may hold the metallic frame209in place on the fixture501. The base210may be placed on the vacuum nozzle503. As shown inFIG. 5b, a strip of piezoelectric material213may be held aloft by a mobile vacuum nozzle504. The mobile vacuum nozzle504may be moved in all three dimensions and is rotatable along the axis of the nozzle504. A camera system505may be used to monitor the placement of the strip of piezoelectric material213. A dispenser places adhesive on the metallic frame209. In one embodiment, the adhesive is epoxy. As shown inFIG. 5c, the mobile vacuum nozzle504may place the strip of piezoelectric material213against the metallic frame209. An ultraviolet source506may be used to cure the epoxy bond between the strip of piezoelectric material213and the metallic frame209. After a time delay of 3–9 seconds, the ultraviolet source506is turned off and the mobile vacuum nozzle504is removed. In an alternate embodiment, the mobile vacuum nozzle504is removed and the ultraviolet source506is turned off. In an alternative embodiment illustrated inFIG. 5d, the fixture501may maintain the structure of multiple metallic frames209. The mobile vacuum nozzle504may place the strip of piezoelectric material213against the arm211of the first metallic frame209. As shown inFIG. 5e, the ultraviolet source506may then cure the epoxy bond before moving to the next metallic frame209.

One embodiment of a method for using the fixture ofFIGS. 5d–eis illustrated in the flowchart ofFIG. 6. To start (Block605), the frame209may be laminated (Block610). The frame209may be placed upon the fixture501(Block615). The strip of piezoelectric material213may be picked up by the mobile vacuum nozzle504(Block620). The location of the strip of piezoelectric material213may be confirmed and then adjustments are made as necessary (Block625). Epoxy may be added to the frame209(Block630). The strip of piezoelectric material213may be attached to the frame209(Block635). The epoxy is cured by ultraviolet radiation (Block640). A camera system505may confirm if further frames209are on the fixture501(Block645). If further frames209are not on the fixture501, the fixture501is exchanged (Block650). Otherwise, the next frame is worked on (Block610).

FIGS. 7a–eillustrate an alternate embodiment of a method for attaching the strips of piezoelectric material213to multiple metallic frames209. As shown inFIG. 7a, a first metallic frame209is placed on a first fixture701and a second metallic frame209is placed on the second fixture702to maintain the structure of the metallic frames209while the strips of piezoelectric material213are added. The first fixture701and the second fixture702may have shaped indentations703to match the exterior of the metallic frame209. Alternately, the first fixture701and the second fixture702may have a shaped protrusion that matches the interior of the metallic frame209. A first vacuum nozzle704embedded within the first fixture701may hold a metallic frame209in place on the first fixture701and a second vacuum nozzle705embedded within the first fixture702may hold a metallic frame209in place on the second fixture702. As shown inFIG. 7b, two strips of piezoelectric material213may be held aloft by a mobile dual vacuum nozzle706. The mobile dual vacuum nozzle706may be moved in all three dimensions. A camera system505may be used to monitor the placement of the strip of piezoelectric material213. A dispenser places adhesive on the metallic frame209. In one embodiment, the adhesive is epoxy. As shown inFIG. 7c, the mobile dual vacuum nozzle706may place the strips of piezoelectric material213against the metallic frames209. A first ultraviolet source707and a second ultraviolet source708may be used to cure the epoxy bonds between the strips of piezoelectric material213and the metallic frames209. After a time delay of 3–9 seconds, the mobile dual vacuum nozzle706is removed and the first ultraviolet source707and the second ultraviolet source708are turned off. In an alternative embodiment illustrated inFIG. 7d, the first fixture701and the second fixture702may each maintain the structure of multiple metallic frames209. The mobile dual vacuum nozzle706may place the strip of piezoelectric material213against the arm211of a first and second metallic frame209. As shown inFIG. 7e, the first ultraviolet source707and the second ultraviolet source708may then cure the epoxy bond before moving to the next two metallic frames209.

FIGS. 8a–fillustrate an alternate embodiment of a method for attaching the strips of piezoelectric material213to the metallic frame209. As shown inFIG. 8a, the two strips of piezoelectric material213may be placed on the fixture801. The fixture801may have a shaped indentation802to match the exterior of the metallic frame209and the two strips of piezoelectric material213. A vacuum nozzle system803embedded within the fixture501may hold the two strips of piezoelectric material213in place on the fixture801. As shown inFIG. 8b, a frame209may be held aloft by a mobile vacuum nozzle804, with the arms oriented downward. The mobile vacuum nozzle804may be moved in all three dimensions and is rotatable along the axis of the nozzle804. A camera system805may be used to monitor the placement of the frame209. As shown inFIG. 8c, a first dispenser806and a second dispenser807may place adhesive on the metallic frame209. In one embodiment, the adhesive is epoxy. As shown inFIG. 8d, the mobile vacuum nozzle804may move about to spread the epoxy evenly on the frame209. As shown inFIG. 8e, the mobile vacuum nozzle804may place the metallic frame209against the strip of piezoelectric material213. As shown inFIG. 8f, a first ultraviolet source808and a second ultraviolet source809may be used to cure the epoxy bond between the strip of piezoelectric material213and the metallic frame209. After a time delay of 3–9 seconds, the mobile vacuum nozzle804may be removed after the first ultraviolet source808and the second ultraviolet source809are turned off. In an alternate embodiment, the mobile vacuum nozzle804may be removed before the first ultraviolet source808and the second ultraviolet source809are turned off.

FIGS. 9a–eillustrate an alternate embodiment of a method for attaching the strips of piezoelectric material213to the metallic frame209. As shown inFIG. 9a, the two strips of piezoelectric material213may be placed on the fixture801. The fixture801may have a shaped indentation802to match the exterior of the metallic frame209and the two strips of piezoelectric material213. A vacuum nozzle system803embedded within the fixture501may hold the two strips of piezoelectric material213in place on the fixture801. A frame209may be held aloft by a mobile vacuum nozzle804, with the arms oriented upward. The mobile vacuum nozzle804may be moved in all three dimensions and is rotatable along the axis of the nozzle804. A camera system805may be used to monitor the placement of the frame209. As shown inFIG. 9b, a first dispenser806and a second dispenser807may place adhesive on the metallic frame209. In one embodiment, the adhesive is epoxy. As shown inFIG. 9c, the mobile vacuum nozzle804may move about to spread the epoxy evenly on the frame209. As shown inFIG. 9d, the mobile vacuum nozzle804may place the metallic frame209against the strip of piezoelectric material213. As shown inFIG. 9e, a first ultraviolet source808and a second ultraviolet source809may be used to cure the epoxy bond between the strip of piezoelectric material213and the metallic frame209. After a time delay of 3–9 seconds, the mobile vacuum nozzle804may be removed after the first ultraviolet source808and the second ultraviolet809may be turned off. In an alternate embodiment, the mobile vacuum nozzle804may be removed before the first ultraviolet source808and the second ultraviolet source809are turned off.

Although several embodiments are specifically illustrated and described herein, it will be appreciated that modifications and variations of the present invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.