Abstract:
Wireless flexures are laser welded to load beams by first reducing the amount of load beam metal with a recess or the combination of a through hole and a recess at the weld location, to thereby reduce the amount of energy need for the weld and distortion to the parts caused by the heat generated during the welding process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Serial No. 60/226,357 filed Aug. 18, 2000. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT NOT APPLICABLE 
     REFERENCE TO A MICROFICHE APPENDIX NOT APPLICABLE 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to disk drive suspensions, and, more particularly, to such suspensions particularly adapted to use in miniature disk drives. Miniature disk drives use smaller suspension components such as shorter and less robust load beams and wireless flexures. These components, having less size and mass, exacerbate the longstanding problems of precisely welding the components without distorting them. Accordingly, there is a need to lower the welding (laser) energy inputs into the load beam and flexure assemblies during manufacture. In the present invention, the load beam rigid portion is modified in advance of welding to reduce the volume of metal to be melted at the weld site enabling the use of less energy to weld, producing less distortion, and a more precise part. 
     2. Description of the Related Art 
     Conventionally, a disk drive suspension is made to the length of 18 mm. In the trend toward miniaturization, 14.5 mm and 11 mm suspensions have been introduced. The suspension typically comprises a stainless steel load beam for structural stiffness, a wireless flexure to provide a head gimbal, and a mount plate, usually fabricated of aluminum for attaching the load beam to an actuator arm. Laser welding is used to join the several components by a series of spot welds. Laser spot welding thus is integral part of the making of suspensions. Such welding provides relatively accurate positioning and good weld strength. Distortions from welding, however, induced by heat stress and/or material flow while in the molten state, can be troublesome. In conventional size suspensions welder through careful monitoring of the welding process routinely minimizes the occurrence of distortions to meet specifications. The arrival of smaller form factor suspensions with their reduced mass, tendency to distort more under the usual working conditions, and more stringent specifications has made existing manufacturing techniques inadequate. Customers are Increasingly imposing stringent visual and dimensional criteria for the laser weld. To compound the issue, particularly in newer suspension designs, more and more laser spot welds are utilized. And, these laser welds are playing a more critical role structurally than ever before. The concrescence of these factors militates a more precise and consistent weld technique and welded product. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object therefore to provide a novel design suspension especially adapted to miniature disk drives. It is a further object to provide a suspension having improved welds with less distortion through the application of less energy into the weld, and less metal flow. A further object is to provide a suspension comprising a flexure and load beam assembly in which the load beam is locally surface etched to have a recess at potential weld sites to decrease the volume of material to be heated and flowed and thus decrease the heat input needed to weld. A still further object is to further reduce material volume and open a heat pipe to the underlying flexure metal layer by adding a smaller diameter opening through the web of metal beyond the etched recess in the load beam. Yet another object is to provide in such a suspension further features including an absence of side rails for lower suspension profile, a grounding structure integrated into the load beam base portion, a single window to the tail connection pads through the insulative film layer, and a mount plate marked for correctly oriented installation. 
     These and other objects of the invention to become apparent hereinafter are realized in a disk drive suspension for smaller disk drives, the suspension comprising a load beam having a base portion adapted for attachment by a mounting plate to an actuator arm, a spring portion, and a weldable metal rigid portion having a first face and an oppositely directed second face, the second face being adapted for attachment of a flexure carrying a slider thereon, the flexure comprising a laminate of a weldable metal layer opposite the second face, an insulative plastic film layer and a plurality of conductive traces spaced from the metal layer by the film layer, the rigid portion first face defining at distributed locations a series of etched recesses that locally reduce the thickness of the rigid portion adjacent the metal layer to be weldable with less energy than the full thickness of the rigid portion, the rigid portion being laser-welded to the flexure metal layer at the recesses. 
     In a further embodiment, the invention provides a smaller disk drive suspension comprising a load beam having a base portion adapted for attachment by a mounting plate to an actuator arm, a spring portion, and a weldable metal rigid portion having a first face and an oppositely directed second face, the second face being adapted for attachment of a flexure carrying a slider thereon, the flexure comprising a laminate of a weldable metal layer opposite the second face, an insulative plastic film layer and a plurality of conductive traces spaced from the metal layer by the film layer, the rigid portion first face defining at distributed locations a series of etched recesses that locally reduce the thickness of the web between the bottom of the recess and the second face adjacent the metal layer to be weldable with less energy than the full thickness of the rigid portion, and including as well a through hole between the bottom of the recess and the second face to further reduce amount of rigid portion and further reduce the amount of energy need to effect a weld, the rigid portion being laser-welded to the flexure metal layer at the recesses. 
     In these and like embodiments, typically, there is further included a cover layer on the laminate covering the conductive traces, and a tail connection pad on the base portion, the tail connection pad having a grounding structure comprising a downwardly stepped aperture through the insulative layer and the conductive traces, and/or the cover layer having a single aperture through to all of the individual pads; there is a mount plate for mounting the load beam base portion to an actuator, the mount plate bearing orientation indicium for correct orientation on the base portion, the orientation indicium comprising a clipped corner on the mount plate, and the load beam rigid portion is free of edge rails, the recess has a diameter of about 0.008 inch, the web has a thickness of about 0.0015 inch, plus or minus 0.006 inch, and the through hole has a diameter between 25% and 75% of the recess diameter, such as 0.004 inch diameter in a 0.008 inch diameter recess. 
     In a highly preferred embodiment, the invention provides a disk drive suspension for smaller disk drives, the suspension comprising a load beam having a base portion adapted for attachment by a mounting plate to an actuator arm, a spring portion, a weldable metal rigid portion free of edge rails and having a first face and an oppositely directed second face, the second face being adapted for attachment of a flexure carrying a slider thereon, the flexure comprising a laminate of a weldable metal layer opposite the second face, an insulative plastic film layer, a plurality of conductive traces spaced from the metal layer by the film layer, and a plastic film cover layer atop the conductive traces, a tail connection pad on the base portion, the tail connection pad having a grounding structure comprising a downwardly stepped circular aperture through the cover layer, the insulative layer and the conductive traces, the tail connection pad comprising a plurality of individual pads, the cover layer having a single aperture through to all of the individual pads, a mount plate for mounting the load beam base portion to an actuator, the mount plate bearing orientation clipped corner indicium for correct orientation on the base portion, the rigid portion first face defining at distributed locations a series of etched recesses that locally reduce the thickness of the web between the bottom of the recess and the second face adjacent -the metal layer to be weldable with less energy and less distortion of the rigid portion and the metal layer than required to weld through the full thickness of the rigid portion, a through hole between the bottom of the recess and the second face to further reduce amount of rigid portion and further reduce the amount of energy need to effect a weld, the rigid portion being laser-welded to the flexure metal layer at the recesses. 
     In its method aspects, the invention provides a method of laser welding a load beam rigid portion to a wireless flexure having a metal layer, including defining in advance of welding a recess in the rigid portion away from the flexure metal layer to provide a reduced thickness web at the bottom of the recess, and laser welding the rigid portion and rigid portion together at the web, or alternatively, also forming a through hole in the web, and laser welding the rigid portion and rigid portion together at the web. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The invention will be further described in conjunction with the attached drawings in which: 
     FIG. 1 is a plan of a suspension according to the invention; 
     FIG. 2 is a view taken on line  2 — 2  in FIG. 1; 
     FIG. 3A is a view taken on line  3 A— 3 A in FIG.  1  and inverted; 
     FIG. 3B is a fragmentary view like FIG. 3 of the load beam rigid portion and its recess and through hole before welding, also inverted; and. 
     FIG. 4 is a fragmentary view like FIG. 3A of a PRIOR ART suspension after welding. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     To help the welders meet increasingly stringent specifications, it is desirable to remove part of the volume of metal in the load beam to lessen what has to be melted and this is achieved by the etching of the load beam at the weld sites. Further reductions in metal volume and better heat transfer to the flexure metal layer are achieved by adding a through hole through the web of metal between the recess bottom wall and the face of the load beam opposite the flexure metal layer. Energy requirements for an effective weld are lowered by 40% or more. Control of the welding process is enhanced. Consistency of the welds is improved since less distortion results from less power used in the welding process. Less power is needed since less material needs to be melted in the welding process, particularly with the through hole in the partial etch area. By varying the partial etch area diameter and through hole size, the welder can optimize the welding process more readily, since the etching dimension is comparatively easily controlled to a very fine resolution. More highly controlled welding results are possible through various combinations of different diameter partial etched areas and through hole sizes. 
     With reference now to the drawings in detail, in FIGS. 1-3B a disk drive suspension  10  for smaller disk drives is shown to comprise a load beam  12  having a base portion  14  adapted for attachment by annular boss  18  of mount plate  16  to an actuator arm (not shown). Load beam  12  further comprises a spring portion  24 , a weldable metal rigid portion  26 , free of edge rails at edges  28 ,  32 , and having a first face  34  and an oppositely directed second face  36 . Load beam second face  36  is adapted for attachment of a flexure  38  suitably carrying a slider (not shown) thereon. 
     Load beam base portion  14  has a tail connection pad  42  formed thereon as shown. The tail connection pad  42  has a grounding structure  44  (see FIG. 2) comprising a downwardly stepped circular aperture  45  through the flexure laminate cover layer  46 , flexure insulative plastic film layer  48  and conductive traces  52 ,  54  to flexure metal layer  50 . Cover layer  46  has an opening  56  therethrough that can be about 0.012 inch in diameter, a communicating opening  58  in the copper traces  52 ,  54  that can be 0.008 inch in diameter, and a further communicating opening  62  in the insulative film layer  48  that can be 0.006 inch in diameter. 
     The tail connection pad  42  further comprises a plurality of individual pads  64 ,  66 ,  68  and  70 . Cover layer  46  has a single aperture  72  at said pads  64 - 70  that opens through to all of the individual pads, rather than a series of individual apertures that register with single individual pads. 
     Mount plate  16  is weld attached to the load beam base portion  14  and mounts the load beam  12  to an actuator (not shown) by mount plate boss  18 . To assist in proper orientation of the mount plate  16  on the load beam base portion  14 , the mount plate is provided with an orienting indicium  74 , a clipped corner  76  that assists in determining the appropriate orientation of the mount plate. Other positioning indicia can be used. 
     For purposes of weld-attachment of the flexure  38  to the load beam rigid portion  26  at sites  78 ,  80 ,  82 , etc. or the flexure to the load beam base portion  14  at  84  for example, the rigid portion first face  34  defines at distributed locations as shown a series of etched recesses  86 . Recesses  86  locally reduce the thickness of the web  88  (FIG. 3B) between the bottom  92  of the recess and the load beam second face  36  at sites  78 ,  80 , etc. adjacent the flexure metal layer  50 . Thus, the load beam  12  volume at the recesses  86  is reduced and the load beam is weldable to the flexure  38  with less energy, a reduced melt zone  93 , and thus less distortion of the rigid portion  26  and the metal layer  50  than might be required to weld through the full thickness of the rigid portion. Through hole  94 , coaxial and smaller in diameter than the recess  86  extends between the bottom  92  of the recess  86  and the load beam second face  36  to further reduce the local volume of rigid portion  26  at the welding sites  78 ,  80 ,  82 , and further reduce the amount of energy need to effect a weld, the rigid portion being laser-welded to the flexure metal layer  50  at the recesses  86 . 
     FIG. 4, a PRIOR ART Figure, in which like parts have like numerals plus  100 , shows the melt zone  193  common to welds accomplished between a load beam  112  and a flexure  138  where there has not been preformed a recess that reduces the volume of load beam metal at the weld site  193 . Compare the representative profile of melt zone  193  with that of the reduced, less wide melt zone  93  in FIG. 3A where the weld is accomplished with the invention recess and through-hole innovations. 
     In its method aspects, the invention provides a method of laser welding a load beam rigid portion  26  to a wireless flexure  38  having a metal layer  50 , including defining in advance of welding a recess  86  in the rigid portion away from the flexure metal layer to provide a reduced thickness web  88  at the bottom  92  of the recess, and laser welding the rigid portion and the metal layer together at the web, or alternatively, also forming a through hole  94  in the web, and laser welding the rigid portion and metal layer together at the web. 
     The invention thus provides a suspension especially adapted to miniature disk drives having improved welds with less distortion through the application of less energy into the weld, and less metal flow by locally surface etching to have a recess and a through opening at potential weld sites to decrease the volume of material to be heated and flowed and thus decrease the heat input needed to weld. The invention further provides in such a suspension an absence of side rails for lower suspension profile, a grounding structure integrated into the load beam base portion, a single window to the tail connection pads through the insulative film layer, and a mount plate marked for correctly oriented installation. 
     The foregoing objects are thus met.