Multi-layer microactuators for hard disk drive suspensions

A multi-layer microactuator for a hard disk drive suspension includes a piezoelectric (“PZT”) layer, a constraining layer, a lower electrode layer, a middle electrode layer, and an upper electrode layer. The lower electrode layer is on a bottom surface of the PZT layer and includes a first lower electrode island, a second lower electrode island, and a third lower electrode island. The second lower electrode island includes a finger extending from a main body portion towards a first end of the PZT layer. The middle electrode layer is disposed between a top surface of the PZT layer and a bottom surface of the constraining layer. The middle electrode layer including a first middle electrode island and a second middle electrode island, the second middle electrode island including a finger extending from a main body portion towards the first end of the PZT layer.

FIELD OF THE PRESENT DISCLOSURE

The present disclosure relates generally to disk drive suspensions and flexures, and more particularly, to multi-layer microactuation assemblies for suspensions and flexures.

BACKGROUND

Disk drive head suspensions are used in hard disk drives (“HDD's”), which read and write media to and from rotating magnetic disks. A suspension is a component of a head gimbal assembly (“HGA”), which includes a plurality of suspensions and magnetic read/write heads (known as a “sliders”). The slider includes transducers to read and write media to one of the rotating magnetic disks. A disk drive head suspension can include various components, including, for example, a flexure, a load beam, a baseplate, and one or more actuation motors. Generally, the actuation motors can be used to precisely position the slider over a rotating magnetic disk to improve the overall performance of the HDD.

There remains a continued need for improved disk drive head suspensions to meet the demands of the HDD industry. Suspensions with enhanced performance capabilities are desired, while being capable of being manufactured efficiently. The present disclosure addresses these and other problems.

SUMMARY

According to some embodiments, a multi-layer microactuator for a hard disk drive suspension includes a piezoelectric (“PZT”) layer, a constraining layer, a lower electrode layer, a middle electrode layer, and an upper electrode layer. The lower electrode layer is on a bottom surface of the PZT layer and includes a first lower electrode island, a second lower electrode island, and a third lower electrode island. The second lower electrode island includes a finger and a main body, the finger extending from the main body towards a first end of the PZT layer. The middle electrode layer is disposed between a top surface of the PZT layer and a bottom surface of the constraining layer and includes a first middle electrode island and a second middle electrode island. The second middle electrode island includes a finger and main body portion, the finger extending from the main body towards the first end of the PZT layer. The upper electrode layer is on a top surface of the constraining layer.

According to other embodiments, a suspension for a hard disk drive includes a load beam, a flexure, and a microactuator. The load beam includes a dimple. The flexure is coupled to the load beam and includes a spring metal layer, an insulating layer, and a conductive layer. The spring metal layer includes a slider mounting region, a first mounting region, and a second mounting region. The slider mounting region has a load point location for engaging the dimple of the load beam. The conductive layer includes a power trace and a ground pad, the motor power trace including a terminal pad. The microactuator includes a piezoelectric (“PZT”) layer, a constraining layer, a lower electrode layer, a middle electrode layer, and an upper electrode layer. The lower electrode layer is on a bottom surface of the PZT layer and includes a first lower electrode island, a second lower electrode island, and a third lower electrode island. The first lower electrode island is electrically connected to the terminal pad. The second lower electrode island includes a finger and a main body portion, the finger extending from the main body portion towards a first end of the PZT layer. The third lower electrode island is electrically connected to the ground pad. The middle electrode layer is disposed between a top surface of the PZT layer and a bottom surface of the constraining layer. The middle electrode layer includes a first middle electrode island and a second middle electrode island. The second middle electrode island includes a finger and main body portion, the finger extending from the main body portion towards the first end of the PZT layer. The upper electrode layer is on a top surface of the constraining layer.

According to other embodiments, a multi-layer microactuation assembly for a hard disk drive suspension includes a piezoelectric (“PZT”) layer, a constraining layer, a lower electrode layer, a middle electrode layer, an upper electrode layer, a first side end electrode, and a second side end electrode. The lower electrode layer is on a bottom surface of the PZT layer and includes a first lower electrode island and a second lower electrode island. The second lower electrode island includes a main body portion and a finger, the finger extending from the main body portion towards a first end of the multi-layer microactuation assembly. The middle electrode layer is disposed between a top surface of the PZT layer and a bottom surface of the constraining layer. The upper electrode layer is on a top surface of the constraining layer. The first side end electrode is coupled to the upper electrode and extends in a direction substantially orthogonal to the upper electrode towards the lower electrode layer. The second side end electrode is coupled to the first lower electrode island and extends in a direction substantially orthogonal to the first lower electrode island towards the upper electrode layer. The second side end electrode is configured to electrically connect the first lower electrode island and the middle electrode layer.

According to other embodiments, a suspension for a hard disk drive includes a load beam, a flexure, and a microactuator. The load beam includes a dimple. The flexure is coupled to the load beam and includes a spring metal layer, an insulating layer, and a conductive layer. The spring metal layer includes a slider mounting region, a first mounting region, and a second mounting region. The slider mounting region has a load point location for engaging the dimple of the load beam. The conductive layer includes a power trace and a ground pad, the motor power trace including a terminal pad. The microactuator includes a piezoelectric (“PZT”) layer, a constraining layer, a lower electrode layer, a middle electrode layer, an upper electrode layer, a first side end electrode, and a second side end electrode. The lower electrode layer is on a bottom surface of the PZT layer and includes a first lower electrode island that is electrically connected to the ground pad and a second lower electrode island that is electrically connected to the terminal pad. The middle electrode layer is disposed between a top surface of the PZT layer and a bottom surface of the constraining layer. The upper electrode layer is on a top surface of the constraining layer. The first side end electrode is coupled to the upper electrode and extends in a direction substantially orthogonal to the upper electrode towards the lower electrode layer. The first side end electrode is electrically connected to the terminal pad via a first volume conductive adhesive. The second side end electrode is coupled to the first lower electrode island and extends in a direction substantially orthogonal to the first lower electrode island towards the upper electrode layer.

The above summary of the present disclosure is not intended to represent each embodiment, or every aspect, of the present disclosure. Additional features and benefits of the present disclosure are apparent from the detailed description and figures set forth below.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

FIG. 1is a partial plan view of a head gimbal assembly including a suspension and a slider. As illustrated inFIG. 1, a head gimbal assembly (“HGA”)1includes a slider2and a suspension10. Generally, the HGA1is used as a component in a hard disk drive (“HDD”), which is an information storage device that records and/or reproduces data from one or more rotating magnetic disks including a pattern of magnetic ones and zeroes. Generally, when assembled in an HDD, the suspension10is coupled to an actuator arm, which in turn is coupled to a voice coil motor that moves the suspension10to accurately position the slider2over a rotating magnetic disk.

As shown, the suspension10includes a load beam12, a flexure20, a first microactuator100, and a second microactuator200. The load beam12is a substantially rigid structure made from one or more metal materials, such as, for example, stainless-steel. The load beam12includes a proximal end14and a distal end16. The load beam12further includes a dimple5, which as explained herein, permits the slider2to pitch and roll relative to the suspension10. This movement of the slider2permits the slider2to follow the data track on a rotating magnetic disk(s) and accounts for vibrations or irregularities on the surface of the rotating magnetic disk(s).

The suspension10can also include a baseplate which is coupled to the load beam12adjacent to the proximal end14. The baseplate can be coupled to the load beam12using a variety of mechanisms, such as, for example, welding or the like. Further, the baseplate is made from one or more metal materials, such as, for example, stainless steel. In an assembled HDD or a head stack assembly, the baseplate is coupled or “swaged” with an actuator arm.

As illustrated inFIGS. 1 and 2A-2B, the flexure20includes a spring metal layer22, an insulating layer38, and a conductive layer40. The flexure20is generally used to electrically connect the slider2to other hard disk drive circuitry, such as, for example, a preamplifier circuit. The flexure20can be coupled to the load beam12using a variety of mechanisms, such as, for example, welding the spring metal layer22of the flexure20to the load beam12.

The spring metal layer22includes a main body24, a first support arm26a, a second support arm26b, a first linkage member28a, a second linkage member28b, and a slider mounting region34. The spring metal layer22is made from one or more metal materials, such as, for example, stainless-steel.

As illustrated, the first and second support arms26a,26bextend from the main body24towards a distal end of the flexure that is adjacent to the distal end16of the load beam12. The first linkage member28aextends from the first support arm26ainwardly towards a longitudinal axis of the flexure20such that the first linkage member28ais positioned between the first support arm26aand the second support arm26b. Likewise, the second linkage member28bextends from the second support arm26bgenerally towards the longitudinal axis of the flexure20such that it is positioned between the second support arm26band the first support arm26a. The slider mounting region34is coupled to the first linkage member28aand the second linkage member28band is generally used to support the slider2. The slider mounting region34includes a load point location that is sized and shaped to engage the dimple of the load beam12. The engagement between the load point location and the dimple of the load beam12allows the slider mounting region34to move relative to the support arms26a,26b. Corresponding movement of the linkage members28a,28bcan be used to control the movement of the slider mounting region34, and thus corresponding movement of the slider2.

The first linkage member28aincludes a first distal mounting region30aand the main body24includes a first proximal mounting region32a. As best illustrated inFIG. 2A, which illustrates a cross-sectional view of a first microactuator of the suspension ofFIG. 1, the first distal mounting region30ais spaced from the first proximal mounting region32a, thereby defining a first actuator opening31ain the spring metal layer22. As explained herein, the first distal mounting region30aand the first proximal mounting region32aare used to support the first microactuator100. Similarly, the second linkage member28bincludes a second distal mounting region30band the main body24includes a second proximal mounting region32b. As best illustrated inFIG. 2B, which illustrates a cross-sectional view of a second microactuator of the suspension ofFIG. 1, the second distal mounting region30bis spaced from the second proximal mounting region32b, thereby defining a second actuator opening31bin the spring metal layer22. As explained herein, the second distal mounting region30band the second proximal mounting region32bare used to support the second microactuator200. The spring metal layer22can further include portions (e.g., tabs) that extend from other structures (e.g., the slider mounting region34or the main body24) to aid in supporting the first microactuator100, the second microactuator200, or both.

The insulating layer38is formed on at least a portion of the spring metal layer22, and the conductive layer40(FIGS. 2A and 2B) is formed on a portion of the insulating layer38and includes a first group of traces42a(FIG. 1) and a second group of traces42b(FIG. 1). Generally, each trace in the first group of traces42aand the second group of traces42bcarries a current (e.g., a signal) along a length of the flexure20. A plurality of traces in the first group of traces42aand the second group of traces42binclude a tail terminal and a slider bonding terminal. The tail terminal of each trace is positioned in a tail region of the flexure20and can be bonded to a preamplifier circuit (e.g., using ultrasonic bonding) or other HDD circuitry when the HGA1is assembled into an HDD. The slider bonding terminal of each trace is positioned in a gimbal region of the flexure20that is generally adjacent to the distal end16of the load beam12and can be bonded to terminals of the slider2(e.g., by soldering) when the slider2is coupled to the slider mounting region34.

The first group of traces42aincludes five traces, including a first power trace44a. The first power trace44aterminates at a first terminal pad46a. As best illustrated inFIG. 2A, the first terminal pad46ais formed on the insulating layer38above the first proximal mounting region32a. The other four traces in the first group of traces42acan be used to carry read or write signals to and from the slider2or can be used as a grounding trace(s). Similarly, the second group of traces42bincludes five traces, including a second power trace44b. The second power trace44bterminates at a second terminal pad46b. As best illustrated inFIG. 2B, the second terminal pad46bis formed on the insulating layer38above the second proximal mounting region32b. The other four traces in the second group of traces42bcan be used to carry read or write signals to and from the slider2or can be used as a grounding trace(s). As explained herein, the first power trace44aand the second power trace44bare generally used to supply power to the first microactuator100and the second microactuator200, respectively.

The first group of traces42aand the second group of traces42bcan be made from one or more conductive materials, such as, for example, copper or a copper alloy. While the first group of traces42aand the second group of traces42bare each shown as including five traces (including a power trace), each group of traces can include any appropriate number of traces (e.g., six traces, eighth traces, twenty traces, etc.), which can be used for any purpose (e.g., carrying read signals to and from the slider2, carrying write signals to and from the slider2, one or more ground traces, etc.). Further, the first group of traces42aand the second group of traces42bcan include the same or different number of traces. The first group of traces42aand the second group of traces42bcan be formed on the insulating layer38using a variety of methods, such as, for example, an additive process, a semi-additive process, or a subtractive process. An outer surface of the first group of traces42aand/or the second group of traces42bcan include a plating layer (e.g., nickel, gold, or any combination thereof).

The conductive layer also includes a first ground pad48aand a second ground pad48b. As best illustrated inFIG. 2A, the first ground pad48ais formed on the first distal mounting region30aof the spring metal layer22of the flexure20. Likewise, as best illustrated inFIG. 2B, the second ground pad48bis formed on the second distal mounting region30bof the spring metal layer22of the flexure20. While the first ground pad48aand the second ground pad48bare shown as being in direct contact with the spring metal layer22, an intermediate conductive layer can be positioned between the ground pads and the spring metal layer22. The intermediate conductive layer can be, for example, one or more electrodeposited layers of conductive material (e.g., gold, nickel, chromium, copper, or the like, or any combination thereof).

The insulating layer38is a dielectric material (e.g., polyimide) that inhibits electrical conductivity between the spring metal layer22and the conductive layer40(e.g., to inhibit electrical shorting between the spring metal layer22and the first group of traces42aand/or the second group of traces42b). According to some embodiments, the flexure20includes a cover layer8that is formed on at least a portion of the first group of traces42a, the second group of traces42b, or both. Like the insulating layer38, the cover layer8is a dielectric material (e.g., polyimide) that aids in inhibiting electrical shorting of the first and second groups of traces42a,42b(e.g., through incidental physical contact with other components) and to protect the traces from damage during handling of the flexure20(e.g., during assembly of the suspension10or the HGA1). The insulating layer38and cover layer8can be the same or different dielectric materials.

As described above, when assembled into a HDD, the suspension10is moved by a voice coil motor to control movement of the slider2over a rotating magnetic disk. The first microactuator100and the second microactuator200are used to more precisely move the slider2to provide substantially finer control of the position of the slider2than the voice coil motor alone. Because both the voice coil motor and the microactuators100,200are used to move the slider2relative to the suspension10, such a suspension is commonly referred to as a dual-stage actuation (“DSA”) suspension. Additionally, the suspension10can include one or more microactuators mounted to the base plate, and such a suspension is commonly referred to as a tri-stage actuation suspension.

As best illustrated inFIG. 2A, the first microactuator100includes a piezoelectric (“PZT”) element layer110, a constraining layer120, a lower electrode layer130, a middle electrode layer142, and an upper electrode layer152. When an actuation voltage is applied to the first microactuator100, the PZT element layer110expands or contracts, changing the length of the first actuator opening31ato cause corresponding movement of the first linkage member28a, the slider mounting region34, and the slider2. The PZT element layer110can be made from, for example, lead zirconate titanate. The term “PZT” is often used as shorthand to refer generally to piezoelectric devices. That shorthand terminology is used herein, and it should be understood that a “PZT” device need not be strictly made of lead zirconate titanate.

As discussed herein, the first microactuator100is coupled to the suspension10(e.g., using conductive adhesive or any other appropriate adhesive). When the PZT element layer110expands, a bottom portion of the PZT element layer110that is directly adjacent to the suspension10does not expand as much as a top portion of the PZT element layer110that is further away from the suspension10. This is because the bottom portion of the PZT element layer110is partially constrained due to the bonding of the first microactuator100to the suspension10. Thus, the top portion of the PZT element layer110expands more than the bottom portion, causing the PZT element layer110to bend during expansion. This bending results in a loss of the overall expansion (often referred to as “stroke length”) of the PZT element layer110. Similarly, when the PZT element layer110contracts, the PZT element layer110bends as well.

The constraining layer120is used to reduce, inhibit, and/or control the bending of the first microactuator100caused by the bottom portion of the PZT element layer110being partially constrained. The constraining layer120is a generally rigid or stiff layer that partially inhibits expansion or contraction of the PZT element layer110and increases the stroke length of the microactuator. More specifically, the constraining layer120can be used to bend the microactuator100in the opposite direction as the bend caused by the expansion or contraction of the PZT element layer110. The constraining layer120can also be used to reduce the likelihood of mechanical failure of the PZT element layer110caused by expansion/contraction or other stresses.

In some implementations, the constraining layer120is made from the same or similar material as the PZT element layer110. This is often referred to as an active constraining layer construction (“CLC”). In such implementations, as explained herein, applying an actuation voltage across the first microactuator100causes opposing movement of both the PZT element layer110and the constraining layer120. For example, if the actuation voltage causes the PZT element layer110to expand, the constraining layer120contracts. Similarly, if the actuation voltage causes the PZT element layer110to contract, the constraining layer120expands.

As illustrated, the lower electrode layer130is formed on a bottom surface of the PZT element layer110and includes a first lower electrode island132, a second lower electrode island134, and a third lower electrode island140. The first lower electrode island132is positioned directly adjacent to a proximal end112of the first microactuator100and the third lower electrode island140is positioned directly adjacent to a distal end114of the first microactuator100. Each of the first lower electrode island132, the second lower electrode island134, and the third lower electrode island140are spaced from one another such that each electrode island is electrically isolated from the others for the PZT poling process. The lower electrode layer130can be made from a conductive metal material, such as, for example, nickel, chromium, gold, copper, or any combination thereof. Further, the lower electrode layer130can be formed on the bottom surface of the PZT element layer110by various mechanisms, such as, for example, sputtering or other deposition processes.

The middle electrode layer142is positioned between the PZT element layer110and the constraining layer120and includes a first middle electrode island144and a second middle electrode island146. The first middle electrode island144is similar to the first lower electrode island132described above in that it is positioned directly adjacent to the proximal end112of the first microactuator100. As illustrated, the first middle electrode island144is generally coincident with the first lower electrode island132, although the first middle electrode island144can be offset or spaced from the first lower electrode island132. The second middle electrode island146is similar to the second lower electrode island134in that it is spaced from the first middle electrode island144, however, the second middle electrode island146extends from the distal end114towards the proximal end112of the first microactuator100. The middle electrode layer142can be made from the same or different materials than the lower electrode layer130. Further, the middle electrode layer142can be formed on the top surface of the PZT element layer110or bottom surface of the constraining layer120using various mechanisms, such as, for example, sputtering or other deposition processes.

As illustrated, the upper electrode layer152is positioned on a top surface of the constraining layer120. Unlike the lower electrode layer130and the middle electrode layer142which comprise a plurality of electrode islands that are spaced from each other, the upper electrode layer152extends from the distal end114of the PZT element layer110to the proximal end112. The upper electrode layer152can be made from the same or different materials as the middle electrode layer142and/or the lower electrode layer130. Further, the upper electrode layer552can be formed on the top surface of the constraining layer120using various mechanisms, such as, for example, sputtering or other deposition processes.

As illustrated inFIG. 2A, the flexure20includes a first volume of conductive adhesive170and a second volume of conductive adhesive172, which are used to couple the first microactuator100to the flexure20of the suspension10. The first volume of conductive adhesive170is positioned on the insulating layer38such that it covers at least a portion of the first terminal pad46aof the first power trace44a(FIG. 1). As illustrated, the first lower electrode island132and the second lower electrode island134of the lower electrode layer130are disposed within and/or contact the first volume of conductive adhesive170. The first volume of conductive adhesive170and the second volume of conductive adhesive172mechanically couple the first microactuator100to the first distal mounting region30aand the first proximal mounting region32aof the spring metal layer22of the flexure20. The first volume of conductive adhesive170electrically connects the first lower electrode island132to the first terminal pad46a, and also electrically connects the second lower electrode island134to the first terminal pad46a. As illustrated, the first volume of conductive adhesive170is sufficiently wide such that both the first lower electrode island132and the second lower electrode island134are both in contact with the first volume of conductive adhesive170. The second volume of conductive adhesive172electrically connects the third lower electrode island140to the first ground pad48a.

The first volume of conductive adhesive170and the second volume of conductive adhesive172can be, for example, an electrically conductive epoxy. The electrically conductive epoxy can include conductive filler particles that aid in permitting electrical conductivity through the volume of epoxy. The conductive filler particles can be, for example, silver particles, gold particles, nickel particles, chromium particles, or the like, or any combination thereof.

The PZT element layer110includes a first electrical via160and a second electrical via162. The first electrical via160electrically connects the first lower electrode island132of the lower electrode layer130and the first middle electrode island144of the middle electrode layer142. The first electrical via160includes a throughhole formed in the PZT element layer110and a column of conductive material disposed in the throughhole. The throughhole can also include a sputtered layer of metal (e.g., copper and/or chromium) formed on walls defined by the throughhole. The sputtered layer of metal can be used to aid in forming the column of conductive material in the throughhole in order to form the first electrical via160. The column of conductive material is coupled to and/or contacts the first lower electrode island132and the first middle electrode island144to provide an electrical connection between the lower electrode layer130and the middle electrode layer142. As described above, the first lower electrode island132is electrically connected to the first terminal pad46a, thus, the first electrical via160electrically connects the first middle electrode island144and the first terminal pad46a. While the cross-sectional view ofFIG. 2Ashows only the first electrical via160between the first lower electrode island132and the first middle electrode island144, any appropriate number of electrical vias can be positioned between the two electrode islands (e.g., two electrical vias, three electrical vias, five electrical vias, etc.).

The second electrical via162is the same as or similar to the first electrical via160described above and electrically connects the third lower electrode island140and the second middle electrode island146. As described above, the third lower electrode island140is electrically connected to the first ground pad48avia the second volume of conductive adhesive172, thus, the second electrical via162electrically connects the second middle electrode island146to the first terminal pad46a. While the cross-sectional view ofFIG. 2Ashows the second electrical via162between the third lower electrode island140and the second middle electrode island146, any number of electrical vias between the two electrode islands is possible (e.g., two electrical vias, three electrical vias, five electrical vias, etc.).

The third electrical via164is the same or similar to the first electrical via160and the second electrical via162, and electrically connects the first middle electrode island144and the upper electrode layer152. Like the first and second electrical vias160,162, the third electrical via164includes a throughhole in the constraining layer120and a column of conductive material. As described above, the first terminal pad46a, the first volume of conductive adhesive170, the first lower electrode island132, the first electrical via160, and the first middle electrode island144are electrically connected, thus, the third electrical via164electrically connects the upper electrode layer152to the first terminal pad46athrough the first microactuator100.

The PZT element layer110is poled in the direction of arrow A1. Similarly, the constraining layer120is poled in the direction of arrow A2, which is generally the same direction as arrow A1. Poling refers to applying a DC voltage across the PZT element layer110and/or constraining layer120for a predetermined period of time to cause a permanent dipole arrangement. Generally, poling occurs only in areas of the PZT element layer110and constraining layer120across which a voltage differential is applied. The other areas that are not poled are often referred to as dead zone areas. Typically, these dead zone areas will be more frequent adjacent to the proximal end112and the distal end114of the microactuator100. When an activation voltage is applied to the microactuator, the areas that are poled will cause the desired movement (e.g., expansion or contraction), while the dead zone areas will not. These dead zone areas are undesirable as they inhibit movement of the microactuator (e.g., leading to reduced stroke length).

As described above, the first power trace44adelivers an electric current to the first terminal pad46a. This current flows through the various components to the upper electrode layer152, and also flows to the second lower electrode island134. As illustrated, the upper electrode layer152has a voltage V and the second lower electrode island134also has a voltage V. On the other hand, the second middle electrode layer146is electrically grounded. This voltage differential with the second middle electrode layer146is the actuation voltage that causes movement of the PZT element layer110and/or the constraining layer120. Because the actuation voltage is applied generally parallel to the poling directions shown by arrow A1and arrow A2, normal strain occurs. More specifically, in the configuration shown, the PZT element layer110expands and the constraining layer120contracts.

Referring toFIG. 2B, the microactuator200is the same as or similar to the first microactuator100and includes a piezoelectric (“PZT”) element layer210, a constraining layer220, a lower electrode layer230, a middle electrode layer242, and an upper electrode layer252. When an actuation voltage is applied to the first microactuator200, the PZT element layer210expands or contracts, changing the length of second actuator opening31bto cause corresponding movement of the second linkage member28b, the slider mounting region34, and the slider2.

The PZT element layer210and the constraining layer220are the same as or similar to the PZT element layer110and the constraining layer120described above. Likewise, the lower electrode layer230is the same or similar to the lower electrode layer130in that it includes a first lower electrode island232, a second lower electrode island234, and a third lower electrode island240. The middle electrode layer242is the same or similar to the middle electrode layer142in that it includes a first middle electrode island244and a second middle electrode island246.

As illustrated, the second microactuator200is coupled to the flexure20of the suspension10in the same or similar manner as the first microactuator100. More specifically, a first volume of conductive adhesive270and a second volume conductive adhesive272are used to couple the second microactuator200to the flexure20.

Like the PZT element layer110, the PZT element layer210includes a first electrical via260and a second electrical via262that are the same as or similar to the first electrical via160and the second electrical via162. The first electrical via260electrically connects the first lower electrode island232of the lower electrode layer230and the first middle electrode island244of the middle electrode layer242. The second electrical via262electrically connects the second middle electrode layer246to the third lower electrode island240. The constraining layer220includes a third electrical via264that is the same as or similar to the third electrical via164, and electrically connects the first middle electrode island244and the third upper electrode layer252.

The PZT element layer210differs from the PZT element layer110in that it is poled in the direction of arrow B1, which is generally the opposite direction of arrow A1. Likewise, the constraining layer220differs from the constraining layer120in that it is poled in the direction of arrow B2, which is generally the same direction as arrow B1.

The second power trace44b(FIG. 1) delivers an electric current to the second terminal pad46b. This current flows through the various components to the upper electrode layer252, and also flows to the second lower electrode island234. As illustrated, the upper electrode layer252has a voltage V and the second lower electrode island234also has a voltage V. On the other hand, the second middle electrode layer246is electrically grounded. This voltage differential is the actuation voltage that causes movement of the PZT element layer210and/or the constraining layer220. Because the actuation voltage is applied generally parallel to the poling directions shown by arrow B1and arrow B2, normal strain occurs. In this configuration, the PZT element layer210contracts and the constraining layer220expands.

As described above, corresponding movement of the first microactuator100and the second microactuator200cause movement of the first linkage member28aand the second linkage member28b, which causes movement of the slider mounting region34. To move the slider2about the load point location and dimple of the load beam12, the first microactuator100and the second microactuator200work in tandem to push/pull the slider2. Because the PZT element layer110and the constraining layer120of the first microactuator100are poled in generally the opposite direction as the PZT element layer210and the constraining layer220of the second microactuator200, and in this example, the first microactuator100generally expands while the second microactuator200generally contracts. This opposing movement causes rotation of the slider2relative to the suspension10to precisely position the slider2on a rotating magnetic disk. If the layers of both the first microactuator100and the second microactuator200were poled in the same direction, the first microactuator100and the second microactuator200would move in the same direction (e.g., both would generally expand), and would not cause the desired movement of the slider2.

FIG. 3is a partial cross-sectional view of a multi-layer microactuator assembly according to an embodiment. As illustrated inFIG. 3, a first microactuator300includes a piezoelectric (“PZT”) element layer310, a constraining layer320, a lower electrode layer330, a middle electrode layer342, and an upper electrode layer352. The PZT element layer310includes a first electrical via360and a second electrical via362. Likewise, the constraining layer320includes a third electrical via364.

While the constraining320and the PZT element layer310are illustrated as being approximately the same thickness, the constraining layer320can be larger (e.g., thicker) than the PZT element layer310or smaller (e.g., thinner) than the PZT element layer310. For example, the length of the constraining layer320can be shorter than the length of the PZT element layer310, such that the microactuator has a step-like shape. The PZT element layer310and the constraining layer320can be made using various methods, such as, for example, coupling the constraining layer320to the PZT element layer310(e.g., using an adhesive), or by forming the constraining layer320on the PZT element layer310using an additive process. In some implementations, the constraining layer320can be a passive constraining layer construction made from, for example, stainless steel, unpoled (unactivated) piezoelectric material, a polymer (e.g., silicon), any other appropriate material, or any combination thereof.

The lower electrode layer330includes a first lower electrode island332, a second lower electrode island334, and a third lower electrode island340. The second lower electrode island334includes a main body portion336and a finger338. The finger338extends from the main body portion336towards a proximal end312of the PZT element layer310. As illustrated, the main body portion336and the finger338both have a generally rectangular shape, although other shapes are possible. Together, the shape and sizes of the main body portion336and the finger338cause the second lower electrode island334to have a general “L” shape.

The finger338of the second lower electrode island334and the first lower electrode island332are spaced from one another such that the second lower electrode island334and the first lower electrode island332are electrically isolated from one another. Likewise, the main body portion336and the first lower electrode island332are spaced from one another. As shown, the finger338extends from the main body portion336all the way to the proximal end312of the PZT element layer310. Alternatively, the finger338can extend from the main body portion336such that is spaced from the proximal end312of the PZT element layer310, so long as there is some overlap between the finger338and the first lower electrode island332.

The middle electrode layer342is similar to the middle electrode layer142in that it includes a first middle electrode island344and a second middle electrode island346. However, unlike the second middle electrode island146, the second middle electrode island346includes a main body portion348and a finger350. The main body portion348extends from the distal end314of the PZT element layer310towards the proximal end312. The finger350extends from the main body portion348to the proximal end312. Both the main body portion348and the finger350are spaced from the first middle electrode island344. As illustrated, the main body portion348and the finger350both have a generally rectangular shape, although other shapes are possible. Together, the shape and sizes of the main body portion348and the finger350cause the second middle electrode island346to have a general “L” shape.

FIG. 4Ais a cross-sectional view of the multi-layer microactuator assembly according to the embodiment illustrated inFIG. 3. As illustrated inFIG. 4A, the first microactuator300is coupled to the flexure20of the suspension1. A first volume of conductive adhesive370mechanically couples the first microactuator300to the first proximal mounting region32aof the spring metal layer22of the flexure20. The first volume of conductive adhesive370also electrically connects the first terminal pad46ato the first lower electrode island332. Further, because the finger338of the second lower electrode island334extends to the proximal end312of the PZT element layer310, the first volume of conductive adhesive370also electrically connects the second lower electrode island334to the first terminal pad46avia the finger338.

The first microactuator300can be coupled to the flexure20of the suspension10using a variety of methods. For example, in a first step, the first volume of conductive adhesive370is dispensed on at least a portion of the insulating layer38and/or the first terminal pad46aand the second volume of conductive adhesive372is dispensed on at least a portion of the first ground pad48a. In a second step, the first microactuator300is then moved towards the flexure20such that the first lower electrode island332contacts the first volume of conductive adhesive370and the third lower electrode island340contacts the second volume of conductive adhesive372. As the first microactuator300moves towards the flexure20, the first volume of conductive adhesive370and the second volume of conductive adhesive372“wick” or flow around the electrode islands. In a third step, the first volume of conductive adhesive370and the second volume of conductive adhesive372are then cured for a predetermined period of time (e.g., ten seconds, thirty seconds, one minute, five minutes, ten minutes, etc.) to couple the first microactuator300to the flexure20.

Advantageously, in this arrangement, the first volume of conductive adhesive370can be substantially smaller in a lengthwise direction than the first volume of conductive adhesive170of the microactuator mounted on a suspension as illustrated inFIG. 2Abecause the first volume of conductive adhesive370does not need to span across the space between the first lower electrode island332and the second lower electrode island334to electrically connect both to the first terminal pad46a. Thus, this arrangement reduces the required conductive adhesive material to manufacture the suspension10.

Further, because the second lower electrode island334extends all the way to the proximal end312of the microactuator300(as opposed to the second lower electrode island134), the finger338reduces dead zones in the PZT element layer310. Because the finger338increases the effective length of the second lower electrode island334, the finger338allows a voltage to be applied across a larger portion of the PZT element310and/or constraining layer320, increasing the areas that can be poled and subsequently activated by the actuation voltage. Similarly, the finger350of the second middle electrode island346aids in reducing dead zone areas in the PZT element layer110and/or the constraining layer320. Again, because the finger350extends the effective length of the second middle electrode island346to which a voltage may be applied, more areas of the PZT element layer310and/or the constraining layer320can be poled and subsequently activated responsive to the actuation voltage.

FIG. 4Bis a cross-sectional view of a second multi-layer microactuator assembly according to the embodiment coupled to a suspension. As illustrated inFIG. 4B, the microactuator300can also be coupled to the second proximal mounting region32band the second distal mounting region30bof the spring metal layer22of the flexure20. As compared to the configuration shown inFIG. 4A, the microactuator300is rotated 180 degrees such that the distal end314is coupled to the second proximal mounting region32band the proximal end312is coupled to the second distal mounting region30b.

As illustrated, a first volume of conductive adhesive470that is the same as or similar to the first volume of conductive adhesive370described above is positioned between the third lower electrode island340and the second terminal pad46b. The first volume of conductive adhesive470mechanically couples the distal end314of the microactuator300to the second proximal mounting region32band electrically connects the second terminal pad46band the third lower electrode island340. Similarly, a second volume of conductive adhesive472is positioned between the second ground pad48band the first lower electrode island332. The second volume of conductive adhesive472mechanically couples the proximal end312of the microactuator300to the second distal mounting region30band electrically connects the second ground pad48band the first lower electrode island332.

As described above and illustrated inFIG. 3, the second lower electrode island334includes the finger338and the second middle electrode island346includes the finger350. Unlike the configuration shown inFIG. 4A, the finger338extends from the main body portion348of the second middle electrode island346such that it is in contact with the second volume of conductive adhesive472. Thus, the second middle electrode island346is electrically connected to the second ground pad48b.

As illustrated inFIGS. 4A and 4B, the PZT element layer310is poled in the direction of arrow C1and the constraining layer320is poled in the direction of arrow C2. In other words, the PZT element layer310and the constraining layer320are both poled in the same direction regardless of whether the microactuator300is coupled to the first distal mounting region30aand the first proximal mounting region32a(FIG. 4A), or the second distal mounting region30band the second proximal mounting region32b(FIG. 4B). As illustrated inFIG. 4A, when an actuation voltage is applied to the microactuator300, there is a voltage V on the upper electrode layer352and there is a voltage V on the second lower electrode island334of the lower electrode layer330. On the other hand, the second middle electrode346is electrically grounded. As a result of this voltage differential shown inFIG. 4A, the PZT element layer310expands and the constraining layer320contracts. As for the microactuator configuration shown inFIG. 4B, when an actuation voltage is applied to the microactuator300, there is a voltage V on the middle electrode layer346while the upper electrode layer352and the second lower electrode334are electrically grounded.

Thus, advantageously, two microactuators that are the same as the microactuator300can be coupled to the flexure20of the suspension10to produce the opposing or push/pull movement of the slider2described above. Rather than having to pole the microactuators in different directions to achieve the push/pull or opposing movement, the two microactuators are simply rotated 180 degrees relative to one another on the flexure20(FIGS. 4A and 4B), simplifying the manufacturing process. In other words, the microactuator300is reversibly mountable on the suspension10. In contrast, because the first microactuator100illustrated inFIG. 2Aand the second microactuator200illustrated inFIG. 2Bdo not include a finger, the first microactuator100cannot be rotated 180 degrees and mounted to the second distal mounting region30band the second proximal mounting region32b. Likewise, the second microactuator200cannot be rotated 180 degrees and mounted to the first distal mounting region30aand the first proximal mounting region32a.

FIG. 5is a cross-sectional view of a microactuator according to an embodiment coupled to the suspension ofFIG. 1. As illustrated inFIG. 5, a microactuator500is coupled to the flexure20of the suspension10(FIG. 1). The microactuator500includes a piezoelectric (“PZT”) layer510, a constraining layer520, a lower electrode layer530, a middle electrode layer542, and an upper electrode layer552. The microactuator500includes a middle electrode layer542configured as a single electrode island.

Further, the microactuator500does not include electrical vias. Instead, the microactuator500includes a first side end electrode554and a second side end electrode556. The first side end electrode554is coupled to a proximal end512of the microactuator500, and more specifically, is coupled to the first lower electrode island532and the upper electrode layer552. The first side end electrode554electrically connects the first lower electrode island532and the upper electrode layer552. As illustrated, the middle electrode layer542is spaced from the first side end electrode554such that the middle electrode layer542is electrically isolated from the first side end electrode554.

The second side end electrode556is coupled to a distal end514of the microactuator500, and more specifically, is coupled to the third lower electrode island540and the middle electrode layer542. The second side end electrode556electrically connects the third lower electrode island542and the middle electrode layer542. As illustrated, the upper electrode layer552is spaced from the second side end electrode556such that the upper electrode layer552is electrically isolated from the second side end electrode556.

The microactuator500is coupled to the flexure20of the suspension10. A first volume of electrically conductive adhesive570couples the proximal end512of the microactuator500to the first proximal mounting region32a. The first volume of electrically conductive adhesive570is dispensed on at least a portion of the first terminal pad46a. As illustrated, the first lower electrode island532and the second lower electrode island534are spaced from one another such that at least a portion of both the first lower electrode island532and the second lower electrode island532are in contact with the first volume of electrically conductive adhesive570. Thus, the upper electrode layer552is electrically connected to the first terminal pad46avia the first volume of electrically conductive adhesive570, the first lower electrode island532, and the first side end electrode554. Similarly, a second volume of electrically conductive adhesive572is dispensed on at least a portion of the first ground pad48a, coupling the distal end514of the microactuator500to the first distal mounting region30a. At least a portion of the third lower electrode island540is in contact with the second volume of conductive adhesive572such that the middle electrode layer542is electrically connected to the first ground pad48avia the second side end electrode556.

FIG. 6is a cross-sectional view of a multi-layer microactuator assembly according to an embodiment coupled to the suspension ofFIG. 1. As illustrated inFIG. 6, a microactuator600is coupled to the flexure20of the suspension1. The microactuator600includes a piezoelectric (“PZT”) element layer610, a constraining layer620, a lower electrode layer630, a middle electrode layer642, an upper electrode layer652, a first side end electrode654, and a second side end electrode656. The lower electrode layer630includes a second lower electrode island634and a third lower electrode island640. The second lower electrode island634is spaced from the first side end electrode654and the third lower electrode island640. The second lower electrode island634extends towards the proximal end612of the microactuator600and the first side end electrode654.

The microactuator600is coupled to the flexure20of the suspension10. A first volume of conductive adhesive670mechanically couples the proximal end612of the microactuator600to the first proximal mounting region32a. Advantageously, by extending the second lower electrode island634towards the first side end electrode654as illustrated inFIG. 6, the first volume of conductive adhesive670can be smaller in a lengthwise direction because it contacts the second lower electrode island634rather than two separate islands. This arrangement also permits a smaller first terminal pad46a, saving on conductive material (e.g., copper) and freeing more space on the flexure20for other components or features (e.g., more conductive traces).

Further, extending the second lower electrode island634further towards the first side end electrode654aids in reducing dead zone areas of the PZT element layer610, the constraining layer620, or both. As shown, a voltage (e.g., V) can be applied to the second lower electrode island634which acts on a larger portion of the PZT element layer610and/or constraining layer620(e.g., compared to the second lower electrode island534). This arrangement allows more of the PZT element layer610and/or constraining layer620to be poled, which reduces dead zones when an activation voltage is applied, and improves the overall performance of the microactuator600.

The first volume of conductive adhesive670extends along a height of the first side end electrode654towards the upper electrode layer652. Thus, the first volume of conductive adhesive670electrically connects the first side end electrode654to the first terminal pad46awithout requiring an intermediate electrode island (e.g., the first lower electrode island532) in the lower electrode layer630. A portion of the first volume of conductive adhesive670can extend upwards towards the upper electrode layer652along the height of the first side end electrode654such that the first volume of conductive adhesive670extends along about 20% to about 80% of the height of the first side end electrode654, about 40% to about 60% of the height of the first side end electrode654, or about 50% of the height of the first side end electrode654.

According to some embodiments, the microactuator600includes a bevel cut680to aid in maintaining electrical isolation between the second lower electrode island634and the first side end electrode654. For example, the bevel cut680can be taken along line682such that the bevel cut680extends through a portion of the first side end electrode654and a portion of the PZT element layer610. The bevel cut680removes a lower portion of the first side end electrode654such that the first side end electrode654is further spaced from the second lower electrode island634to aid in maintaining electrical isolation between the two. The bevel cut680can be made at a variety of angles, such as, for example, between about 15 degrees and about 75 degrees, between about 30 degrees and about 60 degrees, and about 45 degrees.

While the microactuators are illustrated herein and described herein as including a single PZT element layer and a single constraining layer, each microactuator can include any number of PZT element layers and/or constraining layers (e.g., two PZT element layers and two constraining layers, two PZT element layers and one constraining layer, three PZT element layers and three constraining layers, four PZT element layers and three constraining layers, etc.).

Further, while the microactuators as illustrated inFIG. 1are coupled to the suspension10such that a longitudinal axis of each microactuator is generally parallel with a longitudinal axis of the flexure20, the microactuators, such as those described herein, can be angled relative to the longitudinal axis of the flexure20. Angling the microactuators relative to the longitudinal axis of the flexure20can be used to bring the center of rotation for the slider2closer to the dimple. For example, the longitudinal axis of the microactuators described herein may be angled by about 45 degrees relative to the longitudinal axis of the flexure20, although other angles are possible (e.g., between about 30 degrees and about 60 degrees).

While the HGA1as illustrated inFIG. 1and described herein as including the suspension10, in some implementations, the HGA1includes a tri-stage actuation suspension. The tri-stage actuation suspension is similar to the suspension10in that it includes a load beam, a baseplate, and a flexure. The tri-stage actuation suspension differs from the suspension10in that it includes one or more baseplate motors. The one or more baseplate motors can be similar to the microactuators described herein, but differ in that the one or more baseplate motors are coupled to the baseplate rather than the flexure. For example, in such implementations, the baseplate can include mounting regions that are similar to the first distal mounting region30aand the first proximal mounting region32adescribed above for receiving a baseplate motor. The one or more baseplate motors can be configured to move the load beam. To provide power to and/or to control the one or more baseplate motors, the baseplate can include one or more groups of traces including terminal pads and ground pads. Each of the one or more baseplate motors can be coupled to the baseplate using the same or similar mechanisms and methods described above. In such implementations, the baseplate can also include a pseudo feature formed from a metal material (e.g., stainless steel). The pseudo feature is configured to balance out the mass distribution and stiffness of the baseplate. The pseudo feature can be coupled to the base plate using various mechanisms, such as, for example, welding, adhesive, or the like, or any combination thereof. Alternatively, the pseudo feature and the baseplate can be unitary and/or monolithic.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments and methods thereof have been shown by way of example in the drawings and are described in detail herein. It should be understood, however, that it is not intended to limit the disclosure to the particular forms or methods disclosed, but, to the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the disclosure.