FLEXURE-SLIDER BONDING SYSTEM

Abstract

Method and apparatus is provided for controlling unwanted flow of slider bonding adhesive from the flexure tongue portion to the flexure outrigger portion including roughening the tongue portion surface opposite the slider, enclosing the locus of slider attachment fully or partially with a trough etched into the tongue portion, and increasing the depth of fluid adhesive at the locus to increase the adhesive mass and improve the bonding at the slider.

Description

RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisional application Ser. No. 60/088,684, filed Jun. 9, 1998.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the invention

[0003] This invention relates to disk drive suspensions, and more particularly, to the bonding of the sliders in such suspensions to the suspension flexure tongues.

[0004] 2. Related Art

[0005] The flexure tongue of a magnetic or magnetic-optical recording head suspensions has as one of its functions providing a surface for bonding attachment of the slider. This surface is generally flat to provide the maximum bonding surface area between the slider and the flexure tongue. In some designs, this surface also includes a dimple to provide a point of contact and a point of rotation between the flexure and the applied load supplied by the load beam. The adhesive bond between the slider and the flexure tongue is required to carry some of the loads applied to the slider by the external environment. These loads include shear, tension, compression, and bending.

[0006] Of these loads, three immediately test the adhesive bond. Shear (horizontal) load between the suspension and the slider is due to friction of the disk, acceleration of the slider across tracks during accessing (moving to a new radial location on the disk), and horizontal (in the plane of the disk) shock from movement of the disk drive. The tension load the slider applies to the adhesive bond joint between the slider and the flexure tongue is due to vertical shock, and liftoff, as is the bending load. Tension and shear loads are the most significant.

[0007] To achieve an adhesive bond between the slider and the flexure tongue, typically one or more small deposits of fluid, curable adhesive, “dots”, are applied to the flexure tongue portion of the suspension before it is moved into contact with the slider in a bonding fixture which holds the assembly in the exact correct position until enough cure of the adhesive has taken place that the assembled slider/suspension combination can be removed from the fixture safely, that is, without relative movement from the correct position. The cure is then continued without fixturing until the cure is complete. The adhesives are chosen for their low outgassing, long pot life, adhesion strength, environmental and safety compatibility, and cost. It is common to have an adhesive that will spot cure under UV light exposure, and then final cure under thermal (oven cure) process.

[0008] It is known to use a small hole or holes in the flexure tongue as shown in U.S. Pat. No. 5,008,768 to Carlson, Zarouri and Coon to enhance bond strength by forming a rivet-head like structure so that the adhesive will seep through the hole and form a three dimensional bond instead of a two dimensional bond. Other small holes are used to allow UV light to pass through the load beam and flexure to initiate the cure in some types of UV curing adhesives.

SUMMARY OF THE INVENTION

[0009] The requirement for increased bond strength over past requirements stems from the trend toward higher shock loads resistance, i.e. an ability to withstand more “G” forces. The requirement for higher shock load resistance is increasing as more disk drives are being designed for portable/mobile applications.

[0010] This requirement cannot be met by increasing the adhesive area, and thus the areal amount of adhesive, for even as higher bond strengths are needed the trend is to smaller and smaller sliders, so the bonding area available is getting smaller.

[0011] The decrease in size of suspensions and their components has created another difficulty beyond maintaining or increasing adhesive bond strength. The adhesive must be fluid to apply to the bonding surfaces, but should not extend into areas where its presence will interfere with the clearance between the slider/flexure tongue and other parts of the flexure such as the outrigger area or the load beam. The adhesive must be confined to its proper application area and not be permitted to flow (by drip, capillary, run, or otherwise) beyond its intended locus. Ongoing size reductions in suspension parts increase the difficulty of controlling adhesive placement since the clearance between the different parts of the assembly becomes less. Insufficient or poorly placed adhesive will cause a failure, but excess adhesive may bridge between the flexure tongue or slider, its intended locus, and the flexure outrigger or other part of the assembly causing a failure of a different sort.

[0012] Under ideal conditions the bond strength between a slider and flexure tongue will be as high as about 3000 psi. A typical pico or 30% slider provides about 0.002 square inches at most available for bonding. With a 3000-psi adhesive, a slider to flexure tongue bond strength of a maximum of 6 pounds is possible. This is equivalent to several thousand “G”s, and more than sufficient for the applications presently known. Nonetheless, pico slider adhesion sometimes fails, with fatal results to the assembly and a lowering of yields.

[0013] It is an object therefore of the present invention to provide improvements in the bonding of slider to flexure tongues. It is a further object to provide more secure bonding through increases in bond adhesive mass, confinement of the adhesive in the proper locus, and texturing of the bonding surface opposite the slider. It is a further object to control the flow paths of the adhesive to prevent bridging between the tongue and flexure outriggers. Still another object is to increase the apparent length of the tongue edges adhered to the slider for additional bonding improvement.

[0014] These and other objects of the invention, to become apparent hereinafter are realized in basic form by imposing a partial etch pattern on the bonding side, that is the slider-facing side of the flexure tongue to increase the contact area available for the adhesive by roughening it. The etching also serves to diminish or prevent capillary flow of the adhesive toward areas where it is not desired. The area of the flexure tongue where the dimple force is applied on the far (nonslider) side is not etched or otherwise changed so that the contact area of the dimple is as smooth, flat, and stiff as possible. In addition, in a further embodiment, the perimeter of the flexure tongue is increased with etch-formed fingers such that the adhesive will flow across the fingers for increased adhesion but not flow out from the tongue area to the opposing outriggers.

[0015] In particular, the invention provides a disk drive suspension flexure and slider assembly, the flexure comprising an outrigger portion and a tongue portion, the tongue portion having a slider-attaching surface extending in a surface plane, the slider being fluid adhesive-attached to the tongue portion at a predetermined attachment locus on the tongue slider-attaching surface, the slider-attaching surface being surface-etched in surface roughening relation opposite the slider in slowing relation to fluid adhesive flow from the attachment locus.

[0016] In this and like embodiments, typically, the etched slider-attaching surface and the slider are substantially coextensive, and the slider-attaching surface is etched below the surface plane to increase the mass of fluid adhesive at the slider and the strength of the adhesive bond.

[0017] In a further embodiment, the invention provides a disk drive suspension flexure and slider assembly, the flexure comprising an outrigger portion and a tongue portion, the tongue portion having a slider-attaching surface extending in a surface plane, the slider being fluid adhesive-attached to the tongue portion at a predetermined attachment locus on the tongue slider-attaching surface, the slider-attaching surface being surface-etched below the surface plane opposite the slider and at least partially circumferentially of the attachment locus in trough-forming relation against fluid adhesive flow beyond the trough.

[0018] In this and like embodiments, typically: the trough is of uniform depth throughout its length; the trough has a roughened surface for slowing flow of adhesive fluid therethrough; the trough extends fully circumferentially about the attachment locus; the trough defines a repository for the fluid adhesive, whereby the adhesive is locally of a depth greater than the distance between the slider and the surface plane for increased strength in adhering the slider and the attachment surface together; and/or the tongue portion has a perimeter, the tongue portion perimeter being repeatedly reversely deflected for increased perimeter length over a given length of tongue for enhanced adhesion of the fluid adhesive to the tongue portion.

[0019] In yet another embodiment, the invention provides a disk drive suspension flexure and slider assembly, the flexure comprising an outrigger portion and a tongue portion, the flexure tongue portion having a slider-attaching surface extending in a surface plane, the slider being fluid adhesive-attached to the tongue portion at a predetermined attachment locus on the tongue portion slider-attaching surface, the attachment locus being surface-etched opposite the slider in fluid adhesive-containing relation.

[0020] In this and like embodiments, typically: at least one section of the attachment locus is etched below the surface plane in fluid adhesive receiving relation to increase the depth of adhesive to greater than the distance between the slider and the surface plane; the etched attachment locus section has a roughened surface for slowing flow of fluid adhesive in the section; the etched attachment locus section defines a recess extending normal to the surface plane and adapted to receive and retain fluid adhesive in slider-adhering relation; the recess has in a plane parallel to the surface plane a circular or polygonal shape in cross-section; the recess in a plane parallel to the surface plane is cruciform in shape; and/or the recess in a plane parallel to the surface plane has in cross section the shape of a geometric figure of from three to six sides.

[0021] In a further embodiment, the invention provides a disk drive suspension flexure and slider assembly, the flexure comprising an outrigger portion and a tongue portion, the tongue portion having a slider-attaching surface extending in a surface plane, the slider being fluid adhesive-attached to the tongue portion at a predetermined attachment locus on the tongue slider-attaching surface, the slider-attaching surface being surface-etched in recess-defining relation within the attachment locus and surface etched beyond the attachment locus in trough-forming relation against fluid adhesive flow beyond the trough.

[0022] In its method aspects, the invention provides the method of assembling a slider and a flexure having an outrigger portion and a tongue portion having a surface opposite the slider and defining an intended attachment locus for the slider, including etching the tongue portion opposite the slider to form a fluid adhesive receptacle, depositing fluid adhesive onto the attachment locus, and containing the fluid adhesive within the etched portion of the tongue portion against contact of the fluid adhesive with the flexure outrigger portion and to increase locally the depth of the adhesive.

[0023] In this and like embodiments, typically, there is further included etching the fluid receiving receptacle to a depth below the surface of the tongue portion within the attachment locus to increase locally the depth of the adhesive, etching a roughened surface into the tongue beyond the attachment locus against flowing contact of the fluid adhesive with the flexure outrigger portion, and/or etching a fluid adhesive recess into the tongue inward of the etch-roughened surface and within the attachment locus to increase locally the depth of the adhesive.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be further described in connection with the attached drawings in which:

[0025] FIG. 1 is a PRIOR ART Figure showing a bonded slider and tongue in which the adhesive is bridging the gap between the tongue and the outrigger portion of the flexure;

[0026] FIG. 2 is an exploded view of a flexure tongue and slider combination according to the invention;

[0027] FIG. 3 is a side elevation view thereof;

[0028] FIG. 4 is bottom plan view of the bonded tongue and slider in one embodiment;

[0029] FIG. 5 is a view like FIG. 4 of a different embodiment of the invention;

[0030] FIG. 6A is a view like FIG. 4 of a different embodiment of the invention;

[0031] FIG. 6B is a view taken on line 6B in FIG. 6A;

[0032] FIG. 6C is a view taken on line 6C in FIG. 6A;

[0033] FIG. 7A is a view like FIG. 6A of a different embodiment of the invention;

[0034] FIG. 7B is a view taken on line 7B in FIG. 7A;

[0035] FIG. 7C is a view taken on line 7C in FIG. 7A;

[0036] FIG. 8 is bottom plan view of a different embodiment of the invention;

[0037] FIG. 9 is a view like FIG. 8 of a different embodiment of the invention;

[0038] FIG. 10 is an isometric view of a slider tongue assembly in which the tongue has a reversely deflected perimeter edge.

[0039] The invention thus provides improvements in the bonding of slider to flexure tongues, affording more secure bonding through increases in bond adhesive mass, confinement of the adhesive in the proper locus, and texturing of the bonding surface opposite the slider. Moreover, the invention controls the flow paths of the adhesive to prevent bridging between the tongue and flexure outriggers, and increases the apparent length of the tongue edges adhered to the slider for additional bonding improvement. The foregoing objects are thus met.

Claims

1. A disk drive suspension flexure and slider assembly, said flexure comprising an outrigger portion and a tongue portion, said tongue portion having a slider-attaching surface extending in a surface plane, said slider being fluid adhesive-attached to said tongue portion at a predetermined attachment locus on said tongue slider-attaching surface, said slider-attaching surface being surface-etched in surface roughening relation opposite said slider in slowing relation to fluid adhesive flow from said attachment locus.

2. The disk drive suspension flexure and slide assembly according to

claim 1, in which said etched slider-attaching surface and said slider are substantially coextensive.

3. The disk drive suspension flexure and slider assembly according to

claim 1, in which said slider-attaching surface is etched below said surface plane to increase the mass of fluid adhesive at the slider and the strength of the adhesive bond.

4. A disk drive suspension flexure and slider assembly, said flexure comprising an outrigger portion and a tongue portion, said tongue portion having a slider-attaching surface extending in a surface plane, said slider being fluid adhesive-attached to said tongue portion at a predetermined attachment locus on said tongue slider-attaching surface, said slider-attaching surface being surface-etched below said surface plane opposite said slider and at least partially circumferentially of said attachment locus in trough-forming relation against fluid adhesive flow beyond said trough.

5. The disk drive suspension flexure and slider assembly according to

claim 4, in which said trough is of uniform depth throughout its length.

6. The disk drive suspension flexure and slider assembly according to

claim 4, in which said trough has a roughened surface for slowing flow of adhesive fluid therethrough.

7. The disk drive suspension flexure and slider assembly according to

claim 4, in which said trough extends fully circumferentially about said attachment locus.

8. The disk drive suspension flexure and slider assembly according to

claim 4, in which said trough defines a repository for said fluid adhesive, whereby said adhesive is locally of a depth greater than the distance between said slider and said surface plane for increased strength in adhering said slider and said attachment surface together.

9. The disk drive suspension flexure and slider assembly according to

claim 4, in which said tongue portion has a perimeter, said tongue portion perimeter being repeatedly reversely deflected for increased perimeter length over a given length of tongue for enhanced adhesion of said fluid adhesive to said tongue portion.

10. A disk drive suspension flexure and slider assembly, said flexure comprising an outrigger portion and a tongue portion, said flexure tongue portion having a slider-attaching surface extending in a surface plane, said slider being fluid adhesive-attached to said tongue portion at a predetermined attachment locus on said tongue portion slider-attaching surface, said attachment locus being surface-etched opposite said slider in fluid adhesive-containing relation.

11. The disk drive suspension flexure and slider assembly according to

claim 10, in which at least one section of said attachment locus is etched below said surface plane in fluid adhesive receiving relation to increase the depth of adhesive to greater than the distance between said slider and said surface plane.

12. The disk drive suspension flexure and slider assembly according to

claim 11, in which said etched attachment locus section has a roughened surface for slowing flow of fluid adhesive in said section.

13. The disk drive suspension flexure and slider assembly according to

claim 11, in which said etched attachment locus section defines a recess extending normal to said surface plane and adapted to receive and retain fluid adhesive in slider-adhering relation.

14. The disk drive suspension flexure and slider assembly according to

claim 13, in which said recess has in a plane parallel to said surface plane a circular or polygonal shape in cross-section.

15. The disk drive suspension flexure and slider assembly according to

claim 14, in which said recess in a plane parallel to s aid surface plane is cruciform in shape.

16. The disk drive suspension flexure and slider assembly according to

claim 14, in which said recess in a plane parallel to said surface plane has in cross section the shape of a geometric figure of from three to six sides.

17. A disk drive suspension flexure and slider assembly, said flexure comprising an outrigger portion and a tongue portion, said tongue portion having a slider-attaching surface extending in a surface plane, said slider being fluid adhesive-attached to said tongue portion at a predetermined attachment locus on said tongue slider-attaching surface, said slider-attaching surface being surface-etched in recess-defining relation within said attachment locus and surface etched beyond said attachment locus in trough-forming relation against fluid adhesive flow beyond said trough.

18. The method of assembling a slider and a flexure having an outrigger portion and a tongue portion having a surface opposite said slider and defining an intended attachment locus for said slider, including etching said tongue portion opposite said slider to form a fluid adhesive receptacle, depositing fluid adhesive onto said attachment locus, and containing said fluid adhesive within said etched portion of said tongue portion against contact of said fluid adhesive with said flexure outrigger portion and to increase locally the depth of said adhesive.

19. The method according to

claim 19, including also etching said fluid receiving receptacle to a depth below the surface of said tongue portion within said attachment locus to increase locally the depth of said adhesive.

20. The method according to

claim 20, including also etching a roughened surface into said tongue beyond said attachment locus against flowing contact of said fluid adhesive with said flexure outrigger portion.

21. The method according to

claim 21, including also etching a fluid adhesive recess into said tongue inward of said etch-roughened surface and within said attachment locus to increase locally the depth of said adhesive.