Disk drive load arm structure having a strain sensor and method of its fabrication

• US 20070178746A1
• Filed: 01/17/2007
• Published: 08/02/2007
• Est. Priority Date: 01/18/2006
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Maxtor Corporation (Seagate Technology Holdings Plc), Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Tian, Jifang, Guo, Wei, Xu, Yanchu
• Granted Patent: US 7,813,083 B2
• Time in Patent Office: Days
• US Class Current: 439/406
• CPC Class Codes: G11B 5/4813 Mounting or aligning of arm assemblies, e.g. actuator arm supported by bearings, multiple arm assemblies, arm stacks or multiple heads on single arm G11B5/484 takes precedence
• CPC Class Codes: G11B 5/5552 using fine positioning means for track acquisition separate from the coarse (e.g. track changing) positioning means

Abstract

A load arm for a disk drive may include a base section that has an opening for receiving a spindle of a voice coil motor. The base section may have hinge arms that extend from the base section and terminate in tab portions. An arm section may be affixed to the tabs of the hinge arms of the base section such as by spot welding. A head suspension assembly may be affixed to a distal end of the arm section such as by spot welding. A sensor may be provided on a hinge arm of the base section. The sensor may comprise a piezoelectric polymer sensing element and an electrode formed over the piezoelectric polymer sensing element.

Claims

1. A load arm for a disk drive comprising:

a base section having an opening for receiving a spindle of a voice coil motor, the base section having hinge arms extending from the base section and terminating in tabs;

an arm section affixed to the tabs of the hinge arms of the base section;

a head suspension assembly affixed to a distal end of the arm section; and

a sensor formed on a hinge arm of the base section, the sensor comprising a piezoelectric polymer sensing element and an electrode formed over the piezoelectric polymer sensing element.

2. The load arm claimed in claim 1, wherein the arm section is spot welded to the base section.

3. The load arm claimed in claim 1, wherein the head suspension assembly is spot welded to the arm section.

4. The load arm claimed in claim 1, wherein the arm section is spot welded to the base section, and the head suspension assembly is spot welded to the arm section.

5. The load arm claimed in claim 1, wherein the piezoelectric polymer sensing element is formed of polyvinylidene fluoride (PVDF).

6. The load arm claimed in claim 1, wherein the arm section comprises an arm section sensor comprising a piezoelectric polymer sensing element and an electrode formed over the piezoelectric polymer sensing element.

7. A load arm for a disk drive comprising:

a base section having an opening for receiving a spindle of a voice coil motor, the base section having hinge arms extending from the base section and terminating in tabs;

an arm section spot welded to the tabs of the hinge arms of the base section;

a head suspension assembly spot welded to a distal end of the arm section;

a hinge arm sensor formed on a hinge arm of the base section, the hinge arm sensor comprising a polyvinylidene fluoride (PVDF) sensing element and an electrode formed over the PVDF sensing element; and

an arm section sensor formed on the arm section, the arm section sensor comprising a PVDF sensing element and an electrode formed over the PVDF sensing element.

8. The load arm claimed in claim 7, wherein the arm section comprises rail members extending at angles from sides of the arm section to increase rigidity of the arm section.

9. A method of forming a load arm for a disk drive comprising:

providing a substrate comprising a sheet of a structural material and a piezoelectric polymer film formed on a surface of the structural material;

forming sensors on the structural material, the sensors comprising electrodes overlying portions of the piezoelectric polymer film;

masking said sensors and portions of the substrate with a mask defining a base section of a load arm, the mask defining hinge arms of the base section beneath said sensors;

etching the structural material to form a base section corresponding in shape to the mask;

removing the mask from the base section;

affixing an arm section to the base section at tabs extending from the hinge arms of the base section; and

affixing a head suspension assembly to a distal end of the arm section.

10. The method claimed in claim 9, wherein providing a substrate comprises laminating a polyvinylidene fluoride (PVDF) film to a sheet of steel.

11. The method claimed in claim 10, wherein forming sensors comprises:

forming electrodes on the PVDF film; and

etching to remove portions of the PVDF film using the electrodes as etch masks.

12. The method claimed in claim 11, wherein the electrodes are formed by printing a conductive ink on the PVDF film.

13. The method claimed in claim 10, wherein forming sensors comprises:

forming electrodes on the PVDF film;

forming a mask over the PVDF film and the electrodes, the mask defining shapes of the sensors; and

etching to remove portions of the PVDF film unprotected by the mask.

14. The method claimed in claim 13, wherein the mask defining a base section is formed over the mask defining shapes of the sensors after etching to remove portions of the PVDF film.

15. The method claimed in claim 13, wherein the mask defining shapes of the sensors is removed after etching to remove portions of the PVDF film and before forming the mask defining a base section.

16. The method claimed in claim 10, wherein forming sensors comprises forming conductive structures on the PVDF film, the conductive structures comprising sensor electrodes, conductive pads, and conductive traces connecting the sensor electrodes to the conductive pads.

17. The method claimed in claim 16, wherein the sensor electrodes, conductive pads and conductive traces are formed by printing a conductive ink on the PVDF film.

18. The method claimed in claim 9, wherein affixing the arm section is preceded by bending the hinge arms.

19. The method claimed in claim 9, wherein affixing the arm section is followed by bending the hinge arms.

20. The method claimed in claim 9, wherein the arm section comprises spot welding an end of the arm section to the tabs of the hinge arms of the base section.