Wiring thin plate with a wiring part and a protrusion having the same height, flexure as the wiring thin plate and method of welding of the wiring thin plate

Provided is a wiring thin plate capable of securely hold-down the wiring thin plate around a scheduled portion to be a welded spot even if the wiring thin plate is downsized and involves widened wiring traces. The wiring thin plate includes a metal supporting layer, an insulating layer on the supporting layer, a wiring part having a plurality of wiring traces on the insulating layer, a scheduled portion defined on the supporting layer to be welded, and a protrusion formed on the supporting layer for the scheduled portion and having a height that is the same as a height of the wiring part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wiring thin plate applied to a flexure of a head suspension or the like, the flexure of the head suspension and a method of welding the wiring thin plate.

2. Description of Related Art

A hard disk drive incorporates hard disks that are provided so as to rotate at high speed and head suspensions with sliders that are slightly lifted from the respective hard disks to write/read data to and from the hard disks.FIG. 28illustrates a head suspension with a slider disclosed in JP2008-71401A. The head suspension100includes a load beam101, a base plate103and a flexure105attached to the load beam101and the base plate103.

The flexure105includes a wiring part109provided on a metal substrate107and a tongue110on which a slider111is supported. The slider111includes read/write elements to which the wiring part109is connected. In the head suspension, the flexure105is joined to the load beam101and the base plate103at welded spots113,115,117,119and the like by laser welding in general. A tail portion105aof the flexure105extends outward from the base plate103.

The welded spots113,115,117and119are provided at appropriate locations between wiring traces and/or out of the wiring traces or the like in view of locational balance among the welded spots and of locational spaces. In the case of the welded spots117and119provided between the wiring traces, a location between paired wiring traces is avoided for the locations of the welded spots117and119to prevent deterioration in electric characteristic.

When conducting the laser welding to join the flexure105having the wiring to the load beam101and the base plate103, it is extremely important for quality of the welded spots that the flexure105is brought into close contact with the load beam101and the base plate103. If the close contact is insufficient to involve a gap, the laser welding may form a hole and cause scattering and deformation on the flexure105, the load beam101and the base plate103to form a defective nugget.

A metal substrate107of the flexure105is so thin that a portion around a location to be welded needs to be firmly held down by a welding jig.

FIG. 29is a schematic plan view partly illustrating the head suspension around one welded spot ofFIG. 28,FIG. 30is a schematic sectional view partly illustrating the same as well as a welding jig.FIG. 31is a plan view partly illustrating a small head suspension to which a flexure is attached,FIG. 32is a schematic plan view partly illustrating a welded spot of the head suspension ofFIG. 31andFIG. 33is a schematic sectional view partly illustrating the same as well as a welding jig.

As illustrated inFIGS. 28 to 30, the conventional head suspension has a sufficient space to form relatively-large projections114that outwardly protrude from the wiring part109. When the welded spots113are formed on the projections114, each projection114is easily held down around the welded spot113with a circumferential holding portion123bof a welding jig123through which a through hole123agoes.

A recent head suspension, however, is downsized according to downsizing of a hard disk and also involves widened wiring traces. As illustrated inFIG. 31, therefore, the projections125outwardly protruding from the wiring part109in the downsized head suspension have to be downsized. This makes it hard to hold down each projection125around the welded spot129with the conventional welding jig127.

To solve the problem, the holding portion127bof the welding jig127may be downsized as illustrated inFIGS. 32 and 33, The downsized holding portion127b, however, does not effectively hold down the projection125if the welding jig127is deviated or shifted even a little from the most appropriate position.

In particular, the laser welding in practice is conducted to a plurality of semi-finished products that are chained together with a frame to produce a plurality of head suspensions. For this, the welding jig127has a plurality of united holding portions127bfor the respective chained semi-finished products. The united holding portions127bof the welding jig127are positioned to the chained semi-finished products, respectively. Thus, each one holding portion127bis likely to deviate from the corresponding projection125or location to be welded, to cause a problem of the ineffective holding.

Such a problem is occurred at not only the projection125formed to the flexure105and welded to the load beam101but also a projection welded to the base plate and a location between the wiring traces other than the projection. Further, such the problem may be occurred in a wiring thin plate for other products.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a wiring thin plate, a flexure as the wiring thin plate and a method of welding the thin plate capable of securely hold-down the wiring thin plate around a scheduled portion to be a welded spot even if the wiring thin plate is downsized and/or involves widened wiring traces.

In order to accomplish the object, a first aspect of the present invention provides a wiring thin plate, having a supporting layer made of metal, an insulating layer provided on the supporting layer, a wiring part having a plurality of wiring traces provided on the insulating layer, a scheduled portion defined on the supporting layer to be welded for forming a welded spot through which the supporting layer is joined to a metal member, and a protrusion formed on the supporting layer for the scheduled portion and having a height that is the same as a height of the wiring part.

A second aspect of the present invention provides a flexure for a head suspension rising the wiring thin plate according to the first aspect. The flexure includes a slider provided to the supporting layer and having read/write elements to which the wiring part is connected. The supporting layer is to be joined to a base plate or a load beam of the head suspension serving as the metal member through the welded spot to be formed on the scheduled portion.

A third aspect of the present invention provides a method of welding the wiring thin plate according to the first aspect to a metal member. The method includes steps of overlaying the wiring thin plate and the metal member one on another, bringing a flat face of a welding jig into contact with the wiring part and the protrusion of the wiring thin plate so that the flat face spans from the wiring part to the protrusion and a through hole of a welding jig is aligned with the scheduled portion, and conducting welding to the scheduled portion through the through hole to form the welded spot.

According to the first aspect, the wiring thin plate allows a flat face of a welding jig to be brought into contact with the wiring part and the protrusion having the same height around the scheduled portion to be the welded spot. This securely holds down the wiring thin plate around the scheduled portion even if a space for the hold-down is restricted due to the downsizing of the wiring thin plate and the like.

The protrusion is not the wiring part and therefore is adjustable in size and the like when forming the protrusion, and is surely arranged even in a restricted space.

According to the second aspect, the protrusion is allowed to be surely arranged even in a restricted space and the flexure is securely held down around the scheduled portion.

According to the third aspect, the method presses both the wiring part and the protrusion with the flat face of the welding jig to easily and surely hold down the wiring thin plate around the scheduled portion even if the through hole of the welding jig and the scheduled portion are deviated from each other in a measure.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments for a wiring thin plate applied to a flexure of a head suspension and a method of welding the same will be explained. Each embodiment securely holds down the wiring thin plate around a scheduled portion to be a welded spot even if the wiring thin plate is downsized and/or involves widened wiring traces.

The wiring thin plate according to each embodiment includes a supporting layer made of metal, an insulating layer provided on the supporting layer, a wiring part having a plurality of wiring traces provided on the insulating layer, a scheduled portion defined on the supporting layer to be welded for forming a welded spot through which the supporting layer is joined to a metal member, and a protrusion formed on the supporting layer for the scheduled portion and having a height that is the same as a height of the wiring part.

The wiring thin plate may include a projection formed to the supporting layer and protruding outward from the wiring part to define the scheduled portion on the projection, and the protrusion may be continuously or partly provided on a portion of the projection surrounding the scheduled portion.

The wiring thin plate may include an intervening portion of the supporting layer exposed between the wiring traces of the wiring part to define the scheduled portion on the intervening portion, and the protrusion may be circumferentially continuously or circumferentially partly provided on a portion of the intervening portion surrounding the scheduled portion.

The protrusion may have the same sectional layered structure as the wiring past.

The protrusion may be made of the same material as the insulating layer.

The wiring thin plate as the flexure may include a slider provided to the supporting layer and having read/write elements to which the wiring part is connected, and the supporting layer may be to be joined to a base plate or a load beam of the head suspension serving as the metal member through the welded spot to be formed on the scheduled portion.

The flexure may include a tongue onto which the slider is attached provided at a front end portion of the supporting layer in a longitudinal direction and a front projection formed to the supporting layer and longitudinally forward protruding relative to the tongue to define the scheduled portion on the front projection. The protrusion may be formed on a portion of the front projection surrounding the scheduled portion.

The protrusion may be formed onto an edge of the front projection or each one of said edge and a portion between the scheduled portion and the wiring part.

The protrusion may be arranged symmetrically in a sway direction of the head suspension.

A method of welding the wiring thin plate to a metal member, includes steps of overlaying the wiring thin plate and the metal member one on another, bringing a flat face of a welding jig into contact with the wiring part and the protrusion so that the flat face spans from the wiring part to the protrusion and a through hole of the welding jig is aligned with the scheduled portion, and conducting welding to the scheduled portion through the through hole to form the welded spot.

A head suspension and a flexure as the wiring thin plate according to the first embodiment will be explained.FIG. 1is a plan view partly illustrating a small head suspension to which a flexure according to the first embodiment of the present invention is attached. In the following explanation, “right” and “left” mean both sides in a lateral direction (being a sway direction of the head suspension) orthogonal to a longitudinal direction of the flexure, “up” and “down” mean both sides in a thickness direction of the flexure, and “front” and “rear” mean a tongue side and a tail side of the flexure in the longitudinal direction, respectively. The head suspension1according the first embodiment is basically similar to the head suspension100ofFIG. 28according to the related art and thereforeFIG. 28may be referred for the structure of the head suspension1.

The head suspension1ofFIG. 1has a load beam3, a base plate (not illustrated) and a flexure5attached to the load beam3and/or the base plate. The flexure5is an example of the wiring thin pate and supports at a front end thereof a slider (not illustrated) that is used to write and read data to and from a hard disk (not illustrated). As other examples of the wiring thin plate, there are circuit boards of electric parts other than the flexure5.

The flexure5has a metal substrate7and a wiring part9. The metal substrate7is the supporting layer made of metal. According to the embodiment, the metal substrate7is a resilient precision metal thin plate or foil made of, for example, stainless steel having a thickness in the range of, for example, about 12 to 25 μm. The wiring part9includes a plurality of read/write wiring traces arranged on a top face of the metal substrate7. The read and write wiring traces are arranged nearly in parallel in the right-left direction.

The flexure5extends along the load beam3and is firmly fixed to the load beam3and the base plate at given portions (FIG. 28) by laser spot welding. The load beam3and the base plate are metal plates or members made of stainless steel or other metal material. A base end of the flexure5is provided with a tail portion and a front end of the flexure5is provided with a tongue that is supported with a pair of outriggers.

The tongue is pivotally supported with a dimple (not illustrated) formed at a front end of the load beam3. Onto a top face of the tongue, a slider is attached. The slider has read/write elements to which the read/write wiring traces of the wiring part9are connected, respectively.

FIG. 2is a plan view partly illustrating a welded spot11in the longitudinal middle of the flexure5of the head suspension1ofFIG. 1andFIG. 3is a sectional view partly illustrating a sectional structure around the welded spot11ofFIG. 2.FIG. 2corresponds to the part ofFIG. 1rotated by 90° in a clockwise direction.

As illustrated inFIGS. 1 and 2, the metal substrate7includes projections7aand7bon the respective right and left sides of the main body of the metal substrate7in the longitudinal middle. The projections7aand7bare integrated with the main body of the metal substrate7and have wing shapes projected outward from the main body of the metal substrate7in an in-plane direction of the metal substrate7. The projections7aand7bare located out of the wiring part9, allow the metal substrate7to be joined to the load beam3through welded spots11.

The locations of the projections7aand7bofFIGS. 1 and 2are examples and the projections7aand7bmay be arranged on the other locations capable of joining the metal substrate7to the load beam3and/or the base plate by welding.

In each one of the projections7aand7b,a protrusion13is continuously provided on a portion of the projection surrounding the welded spot11formed by spot welding. The welded spot11corresponds to a scheduled portion to be welded by the spot welding in a discrete flexure5that has not been attached to the load beam3or the base plate. The protrusions13of the respective projections7aand7bare symmetric and have the same structure. Regarding the right and left projections7aand7band the right and left protrusions13, therefore, only the right projection7aand the right protrusion13will be explained.

According to the embodiment, the protrusion13is continuously formed onto and along an edge of the projection7aand is electrically insulated from the wiring part9as explained later to compose a simple protrusion.

The protrusion13has a first portion13a, a second portion13band a third portion13c. The first portion13ahas a linear shape extending in a front-rear direction or longitudinal direction. The first portion13ais located away from the wiring part9in the right-left direction. The second portion13bhas a linear shape extending in a right-left direction or lateral direction and spans from the wiring part9to the first portion13a.The third portion13chas an arc shape extending from the first portion13ato the wiring part9. Between the first portion13aand the second portion13b,a first corner portion13dis formed to connect ends of the first and second portions13aand13bto each other. Between the first portion13aand the third portion13c,a second corner portion13eis formed to connect ends of the first and third portions13aand13cto each other. The first and second corner portions13dand13ehave an arc shape. With this configuration, the protrusion13is led from and to the wiring part9to encircle the welded spot11.

As illustrated inFIG. 3, the protrusion13according to the embodiment has the same sectional layered structure as the wiring part9and is entirely a dummy wiring part.

The wiring part9in the sectional structure includes a base layer14, wiring traces15and a cover layer17.

The base layer14is made of insulating resin such as polyimide. The base layer14is a thin plate layered on the metal substrate7, and in particular on a top face of the metal substrate7. The base layer14secures electrical insulation for the wiring traces15. According to the embodiment, the base layer14extends along the back faces (lower faces inFIG. 3) of the wiring traces15in a routing direction of the wiring traces. In the cross section on a plane orthogonal to the routing direction, the base layer14is formed into a flat shape so as to span the wiring traces15in the right-left direction. The base layer14has a thickness in a range of, for example, about 10 to 20 μm. This thickness, however, may be adjusted depending on a required dielectric strength voltage.

A plurality of the wiring traces15are arranged for read/write function and/or other optional functions and each one wiring trace15is made of for example, highly conductive metal such as copper. The wiring trace15is a thin plate or bar layered on the base layer14, and in particular on a top face of the base layer14. The wiring trace15has a rectangular section with a thickness in a range of for example, about 3 to 18 μm.

The cover layer17is a thin plate that covers the wiring past9and is made of insulating resin such as polyimide. The cover layer17coats the wiring traces15of the wiring part9so as to have a thickness less than the base layer14. The thickness of the cover layer17is set in a range of, for example, about 1 to 5 μm.

The protrusion13in the sectional layered structure includes a base layer19, a conductive layer21and a cover layer23. The protrusion13has the constant sectional shape in an extending direction thereof and has the same height as the wiring part9. The protrusion13may vary in sectional shape in the extending direction e.g. vary in width in the plan view ofFIG. 2as long as the protrusion13has the same height as the wiring part9.

The base layer19corresponds to the base layer14of the wiring part9. Similarly, the conductive layer21corresponds to the wiring trace15and the cover layer23corresponds to the cover layer17. The base layer19, the conductive layer21and the cover layer23of the protrusion13are formed as the dummy wiring part simultaneously with the base layer14, the wiring traces15and the cover layer17of the wiring part9, respectively.

The base layer19of the protrusion13is a band or plate having a rectangular section with a wider width than the conductive layer21, to stably support the conductive layer21and reinforce the projection7awith a band region spanning inward from the outer edge of the projection7a. The outer edge of the base layer19is located onto and along the outer edge of the projection7a.Namely, the outer edges of the base layer19and the projection7amatch with each other in the plan view. The outer edge of the base layer19may be entirely or partly shifted inward from that of the projection7a.

The conductive layer21of the protrusion13is a thin plate or bar having the same sectional shape as the wiring trace15and serves as a core of the protrusion13.

The cover layer23of the protrusion13has a top wall23a,side walls23band flanges23cso as to cover or coat a top face and side faces of the conductive layer21. As illustrated inFIGS. 2 and 3, the top wall23ais the portion covering the top face of the conductive layer21and the side walls23bthe portions covering the respective side faces of the conductive layer21. The flanges23coutward extend from the side walls23bso that lateral outer edges of the flanges23cmatch with the respective lateral outer edges of the base layer19in the plan view. The outer edge of the lateral outer flange23c, therefore, is located onto and along the outer edge of the projection7a.

The top wall23aof the protrusion13has a top face23aabeing flat in the same way as the top face9aof the wiring part9. The top face23aaof the top wail23ais positioned at the same height from the metal substrate7as the top face9aof the wiring part9. The heights of the wiring part9and the protrusion13may be different from each other within tolerance that allows the wiring part9and the protrusion13to be simultaneously pressed with a flat face of a flat welding jig.

The conductive layer21of the protrusion13is separated from the wiring traces15though the protrusion13is continuously formed from the wiring part9as mentioned above. The base layer19and the cover layer23integrally continue to the base layer14and the cover layer17of the wiring part9, respectively.

The electric separation of the protrusion13with respect to the wiring part9may be established at any part of the protrusion13in a continuation direction of the protrusion13. According to the embodiment, the electric separation relative to the wiring part9is established at ends of the protrusion13in the continuation direction. The electric separation may be at a center of the protrusion13in the continuation direction.

The protrusion13may have a different sectional shape from the wiring part9as long as the top face23aaor the top edge of the protrusion13has the same height as the top face9aor the top edge of the wiring part9. For example, the protrusion13has a sectional shape such as semi-circular, semi-oval, trapezoidal, inverted-trapezoidal, triangular, or inverted-triangular section that maintains the height of the top face23aaor the top edge of the protrusion13being the same as that of the top face9aor the top edge of the wiring part9. The flanges23cmay be omitted and accordingly the width of the base layer19may be reduced so that the protrusion13has a simple rectangular section.

The protrusion13may be wholly made of the same material as the base layer19with absence of the conductive layer21and the cover layer23. Namely, the protrusion13may be a part of the base layer19so as to protrude from the top face of the base layer19and have the same height as the wiring part9.

The method of welding the flexure5will be explained with reference toFIG. 4 and 5in whichFIG. 4is a schematic plan view partly illustrating the welded spot11in the longitudinal middle of the flexure5of the head suspension1ofFIG. 1in relation to the welding jig29andFIG. 5is a schematic sectional view taken along a line V-V ofFIG. 4.

FIGS. 4 and 5indicate only one welded spot11in one head suspension1that is one of head suspensions chained by a frame. When manufacturing the chained head suspensions, the flat welding jig holds down flexures5of semi-finished head suspensions around a plurality of scheduled portions to be welded all at once. Then, welded spots are formed by spot welding on the respective scheduled portions to form the chained head suspensions.

The method, before the welding, overlays the flexure5as the wiring thin plate and the load beam3and/or the base plate as the metal member one on another. In particular, the load beam3and the flexure5are put on a workbench28in this order to lay a part of flexure5on the load beam3as illustrated inFIG. 5. The base plate is also put on the workbench28while the base plate and the load beam3are partly laid on each other and another part of the flexure5is laid on the base plate likeFIG. 28.

Then, the flat welding jig29is put on the stack of the load beam3(and the base plate) and the flexure5, thereby to bring the flat face29bof the welding jig29into contact with the wiring part9and the protrusion13so that the flat face29bspans from the wiring part9to the protrusion13. In particular, the flat face29bsimultaneously contacts with the top face9aof the wiring part9and the top face23aaof the protrusion13having the same height. The welding jig29is a flat plate having the flat face29b.The welding jig29, however, is enough to have the flat face29bspanning from the wiring part9to the protrusion13and therefore may include irregularity on the other portion of the jig29excluding the flat face29b.

The welding jig29has a through hole29athat is provided for each one scheduled portion to be welded. The through hole29ais positioned over and aligned with the corresponding scheduled portion when the flat face29bof the welding jig29is brought into contact with the wiring part9and the protrusion13.

Even if the welding jig29is deviated or shifted from the most appropriate position, the welding jig29keeps on hold-down the metal substrate7of the flexure5around the scheduled portion by applying load onto the wiring part9and the protrusion13as long as the flat face29bspans from the wiring part9to the protrusion13. Namely, the welding jig29surely applies the hold-down force to the metal substrate7or the flexure5around the scheduled portion through the wiring part9and the protrusion13.

According to the embodiment, the welding jig29entirely holds down the projection7aalong the edge of the projection7aof the metal substrate7of the flexure5. This brings the projection7ainto close contact with the load beam3to which the projection7ais welded.

In particular, since the protrusion13is continuous with the wiring part9and is continuously extended along the edge of the projection7a,the protrusion13allows the projection7ato be surely held down at the edge even if the projection7aforms the thin single layer as well as the metal substrate7and has the wing shape.

Since the held-down projection7ais circumferentially pressed through the wiring part9and the protrusion13, the whole projection7aincluding the scheduled portion surely close contacts with the load beam3.

In this state, the scheduled portion is exposed outside through the through hole29aof the welding jig29and then the spot welding is conducted to the scheduled portion through the through hole29ato form the welded spot11. With the welded spot11, the metal substrate7or the flexure5is joined to the load beam3. To the base plate, the metal substrate7or the flexure5may be joined in the same way as the above.

As mentioned above, the flexure5as the wiring thin plate according to the first embodiment includes the metal substrate7, the insulating base layer14provided on the metal substrate7, the wiring part9having the plurality of parallel wiring traces15provided on the insulating base layer14, the scheduled portion defined on the metal substrate7to be welded for forming the welded spot11through which the metal substrate7is joined to the load beam3or the base plate (not illustrated) as a metal member, and the protrusion13formed on the metal substrate7for the scheduled portion and having the height that is the same as the height of the wiring part9to allow the flat face29bof the welding jig29to be brought into contact with the protrusion13and the wiring part9.

Accordingly, the metal substrate7of the flexure5is surely brought into close contact with the load beam3at the projections7aand7bfor the scheduled portions when conducting the spot welding. Further, other scheduled portions (not illustrated) each including the protrusion13are surely brought into close contact with the load beam3or the base plate. This securely holds down the flexure5around the scheduled portions. With this, the embodiment obtains the welded spot11and the other welded spots with high quality.

According to the embodiment, the protrusion13is not the wiring part9but the dummy wiring part. If the protrusion13is formed as a part of the wiring part9, this modified structure causes the following problems though it provides the aforementioned effect.

First, it is difficult to arrange wiring traces each having a widened width due to low impedance in a restricted area around a scheduled portion.

Only one narrow wiring trace such as read wiring trace may be arranged in the restricted area. This structure, however, deteriorates the electric characteristic.

Further, the right and left outer wiring traces frequently have different widths. If the right and left outer wiring traces are arranged around the respective scheduled portions, this breaks the right-left symmetry and deteriorates a dynamic characteristic of the head suspension.

In contrast, the first embodiment does not involve such problems. Further, the protrusion13is adjustable in size and the like when forming the protrusion13.

According to the embodiment, the flexure5has the projection7aand the protrusion13is continuously provided on a portion of the projection7asurrounding the scheduled portion.

Thus, even if the head suspension1is downsized and/or involves the widen wiring traces15and the projection7ais not enough to be held down for the related art, the embodiment surely brings the projection7ainto close contact with the load beam3using protrusion13to maintain the quality of the welded spot11.

The protrusion13serves as a rib reinforcing the edge of the projection7ato contribute the close contact of the projection7ato the load beam3.

The protrusion13is the dummy wiring part having the same sectional layered structure as the wiring part9and is easily formed simultaneously with the wiring part9. Further, the protrusion13being the dummy wiring part has the width that is allowed to be freely set regardless of the actual wiring part9.

If the protrusion13is entirely formed by the same material as the base layer19i.e. is the integrated part of the base layer19, the protrusion13needs no conductive layer and no cover layer and has the simplified structure to further reduce the manufacturing cost.

The method of welding the flexure5as the wiring thin plate to the load beam3or the base plate as the metal member, includes the steps of overlaying the flexure5and the load beam3(and the base plate) one on another bringing the flat face29bof the flat welding jig29into contact with the wiring part9and the protrusion13of the flexure5so that the flat face29bspans from the wiring part9to the protrusion13and the through hole29aof the welding jig29is aligned with the scheduled portion, and conducting spot welding to the scheduled portion through the through hole29ato form the welded spot11.

This method allows the projection7ato be surely held down using the flat welding jig29without holding convex portions or poles that should be arranged on the portion surrounding the scheduled portion, thereby to contribute downsizing of the head suspension1.

The present invention is applicable to a head suspension regardless of size. Namely, the present invention allows the flat welding jig to be used to sufficiently hold down the metal substrate7around the scheduled portion regardless of size of the head suspension1.

The use of the flat welding jig29prevents the influence of the deviation or shift of the welding jig29on the close contact of the metal substrate7or the projection7ato the load beam3and/or the base plate.

The projection7ais held down through the protrusion13being the dummy wiring part to prevent scratches from being generated on the top face of the metal substrate7.

The first to fourth modifications of the first embodiment will be explained with reference toFIGS. 6 to 9that are plan views each illustrating the welded spot in the longitudinal middle of the flexure of the head suspension ofFIG. 1. InFIGS. 6 to 9, only one projection (right projection) is indicated. Since the other projection (left projection) has the same structure, only the right projection and the right protrusion will be explained. The modifications are basically the same as the first embodiment and therefore the corresponding components are represented with the same reference numerals or the same reference numerals plus “A” to “D” to omit repetition of explanation.

As illustrated inFIGS. 6 to 9, the protrusion may be partly provided on a portion of the projection7asurrounding the scheduled portion.

According to the first modification ofFIG. 6, the protrusion13A is provided with a cutout or gap13Ada based on the protrusion13of the first embodiment. The gap13Ada is located at the corner7aaof the projection7a.Namely the protrusion13A is equivalent to the shape in which the first corner portion13dofFIG. 2is cut off from the protrusion13. The ends of the first and second portions13aand13bfacing the gap13Ada is formed into a semi-circular shape without angles in the plan view.

The first modification, therefore, allows inert gas to be controlled by the gap13Ada at the time of welding. Namely, the inert gas is introduced into a space between the welding jig29and the projection7ato prevent welding burning of the projection7aand then is discharged from the gap13Ada for the control of the inert gas.

According to the second modification ofFIG. 7, the protrusion13B is provided with gaps13Bba,13Bca and13Bda based on the protrusion13of the first embodiment. The gap13Bda is located at the corner7aaof the projection7a.The gap13Bba is formed between the second portion13Bb of the protrusion13B and the wiring past9by removing a part of the second portion13bof the protrusion13ofFIG. 2. The gap13Bca is formed between the first portion13Ba and the wiring part9by removing the third portion13cof the protrusion13ofFIG. 2.

The second modification, therefore, allows inert gas to be controlled by the gaps13Bba,13Bca and13Bda at the time of welding. Namely, the gaps13Bba,13Bca and13Bda discharge the inert gas introduced into the space between the welding jig29and the projection7ato conduct the control of the inert gas.

According to the third modification ofFIG. 8, the protrusion13C is provided with gaps13Cba and13Cca based on the protrusion13of the first embodiment. The gaps13Cba and13Cca are the same as the respective gaps13Bca and13Bca ofFIG. 7.

The third modification, therefore, allows inert gas to be controlled by the gaps13Cba and13Cca at the time of welding.

According to the fourth modification ofFIG. 9, a plurality of discrete protrusions13Da,13Db and13De are formed instead of the protrusion13B of the second modification. Each protrusion has a circular cylindrical shape. The protrusions13Da,13Db and13De are arranged in the region of the protrusion13B inFIG. 7, in particular in the respective regions of the first portion13Ba, the second portion13Bb and the second corner portion13Be of the protrusion13B.

Intervals between adjacent protrusions are not uniform. In the set of the protrusions13Db, the intervals closer to the corner portion7aaof the projection7aare relatively wide. In the set of the protrusions13Da, the intervals are relative narrow. One of the protrusions13Db closest to the corner portion7aais positioned at the one end of the corner portion7aaand one of the protrusions13Da closest to the corner portion7aais positioned slightly away from the other end of the corner portion7aa. Another one of the protrusions13Da closest to the corner portion7abof the projection7ais positioned on the one end of the corner portion7aband the protrusion13De is positioned at the other end of the corner portion7ab. The interval between the protrusion13De and the adjacent protrusion13Da is relatively wide.

The fourth modification, therefore, allows inert gas to be controlled by the intervals between the adjacent protrusions and the gaps13Dba,13Dca and13Dda at the time of welding.

The intervals between the adjacent protrusions are optional and may be changed according to the control of the inert gas. The protrusions13D are formed instead of the protrusion13,13A or13C and accordingly arranged in the region of the protrusion13,13A or13C.

The first embodiment including the first to fourth modifications is applicable to the other welded spot or scheduled portion of the flexure5for welding the flexure5to the load beam3and/or the base plate. The protrusion may be formed for some selected welded spots or scheduled portions. In this case, the welding jig may be provided with the holding convex portion of the related art for the welded spot or scheduled portion for which the protrusion is not formed.

The second embodiment will be explained.FIG. 10is a plan view partly illustrating a front end portion of a flexure around a welded spot according to a comparative example andFIG. 11is a plan view partly illustrating a front end portion of a flexure around a welded spot according to the second embodiment of the present invention. In the second embodiment, components corresponding to those of the first embodiment are represented with the same reference numerals or the same reference numerals plus “F” to omit repetition of explanation.

As the comparative example illustrated inFIG. 10, the head suspension includes the head. In the head, the metal substrate7at a front end portion thereof is provided with the tongue30onto which the slider (FIG. 28) is attached. The slider includes the read/write elements to which the wiring traces of the wiring part9are electrically connected. The wiring part9is schematically illustrated inFIG. 10. The wiring part9has the same sectional layered structure as the wiring part9ofFIG. 3.

The metal substrate7has a front projection7clongitudinally forward protruding relative to the right and left outriggers25and therefore the tongue30. On the front projection7c,a welded spot27is formed to join the metal substrate7and the front end of the load beam (FIG. 28).

Based on the comparative example, the second embodiment ofFIG. 11is provided with a protrusion29F. The protrusion29F is formed on a portion of the front projection7csurrounding the scheduled portion to be welded. According to the embodiment, the front projection7chas an edge7din the center of the right-left direction. The edge7dhas a forward convex arc shape. Onto the edge7d,the protrusion29F is formed. With this, the protrusion29F has an arc shape with the center of curvature located onto the center of the welded spot27in the plan view and circumferentially partly surrounds the welded spot27on a front side thereof at a distance. The protrusion29F is symmetrically arranged across the welded spot27or the scheduled portion in the sway direction or the right-left direction of the head suspension1. Right and left ends of the protrusion29F are out of the edge7dand led to a main portion of the front projection7c.

The metal substrate7has one or more bends in a pitching direction around the front projection7cand the front projection7cis a portion having no influence of such bends.

The protrusion29F has the same sectional structure as the protrusions13of the first embodiment so that the height of the protrusion29F is the same as that of the wiring part9. The heights of the protrusion29F and the wiring part9are measured from the top faces of specified regions of the metal substrate7on which the protrusion29F and the wiring part9are located to the top faces of the protrusion29F and the wiring part9, respectively.

When conducting welding, the flat face29bof the flat welding jig29(FIG. 5) spans from the wiring part9to the protrusion29F to press the same. Thus, the second embodiment securely holds down the front projection7cincluding the scheduled portion on the front end portion of the load beam3and therefore securely forms the welded spot27in comparison with the comparative example ofFIG. 10. Further, the protrusion29F reinforces the edge7dof the front projection7cof the metal substrate7.

FIGS. 12 to 14are plan views illustrating the first to third modifications of the second embodiment. The modifications are basically the same as the second embodiment and therefore the corresponding components are represented with the same reference numerals or the same reference numerals plus “G” to “I” to omit repetition of explanation.

The first to third modifications form a protrusion onto each one of the edge7dof the front projection7cand a portion between the scheduled portion and the wiring part9.

The first modification ofFIG. 12has the discrete protrusions29G and31G. The protrusion29G is the same as the protrusion29F ofFIG. 11. The protrusion31G is arranged on a rear side of the welded spot27to face the projection29F across the welded spot27and is next to the wiring part9in the front-read direction. The protrusion31G has a straight shape extending in the right-left direction in the plan view. The protrusion31G has the same sectional layered structure as the protrusion29G to have the same height.

When conducting welding, the flat face29bof the flat welding jig29spans from the wiring part9and the protrusions29G and31G to press the same. Thus, the first modification securely forms the welded spot27in comparison with the comparative example ofFIG. 10.

The second modification ofFIG. 13has the discrete protrusions29Ha,29Hb and31H. The protrusions29Ha and29Hb are formed instead of the protrusion29G ofFIG. 12and the protrusion31H is the same as the protrusion31G ofFIG. 12.

The protrusions29Ha and29Hb are separated by a gap29Hc arranged on a center based on the protrusion29G ofFIG. 12.

The second modification, therefore, easily controls with the presence of gap29Hc the inert gas to avoid welding burning in comparison with the first modification ofFIG. 12.

The third modification ofFIG. 14is equivalent to the structure in which the protrusion31H ofFIG. 13is omitted in the second modification. Namely, the third modification has the protrusions29Ia and29Ib and the gap29Ic that are the same as the29Ha and29Hb and the gap29Hc ofFIG. 13, respectively.

The third embodiment will be explained.FIG. 15is a plan view partly illustrating a welded spot in the longitudinal middle of a flexure of a head suspension according to the third embodiment of the present invention.FIG. 16is a plan view partly illustrating a protrusion around the welded spot ofFIG. 15, andFIG. 17is a sectional view partly illustrating the protrusion around the welded spot ofFIG. 15. In the third embodiment, components corresponding to those of the first or second embodiment are represented with the same reference numerals or the same reference numerals plus “J” to omit repetition of explanation.

According to the third embodiment, the welded spot or scheduled portion is arranged on an intervening portion of the metal substrate7between the wiring traces of the wiring part9. The third embodiment is applicable regardless of size in a wiring interval between the adjacent wiring traces.

As illustrated inFIGS. 15 and 16, the wiring traces of the wiring part9are branched into a fork to expose the intervening portion7eof the metal substrate7. On the intervening portion7e,the welded spot35is formed. According to the embodiment, the flexure5has the protrusion33circumferentially continuously provided on a part of the intervening portion7esurrounding the scheduled portion to be welded spot35at a distance. The protrusion33has the same height as the wiring part9.

The protrusion33of the present embodiment has a circular annular or ring shape that encircles the welded spot35in the plan view. An inner diameter of the protrusion33is slightly larger than that of the through hole29Ja of the welding jig29J.

As illustrated inFIG. 17, the sectional layered structure of the protrusion33is the same as that of the wiring part9on each side of the protrusion33in the right-left direction. Namely, the protrusion33has the base layer19J, the conductive layer21J and the cover layer23J equivalent to the base layer19, the conductive layer21and the cover layer23of the protrusion13ofFIG. 3. The base layer19J has the circular annular or ring shape with a constant radial width and the conductive layer211is formed on the base layer19J to have a circular or ring shape with a narrower radial width than the base layer19J. The cover layer23J includes the top wall23Ja, the side walls23Jb and the flanges23Jc. The flat top face of the top wall23Ja is positioned at the same height as the top face9aof wiring part9on each side of the protrusion33in the right-left direction.

The protrusion33may have a different sectional shape like the protrusion13of the first embodiment. The protrusion33may be wholly made of the same material as the base layer19J in the same way as the protrusion13. The width of the protrusion33is not necessarily constant in the whole circumference and may be partly changed or have a radially inward or outward convex portion. These may be also applied to the following modifications of the third embodiment.

According to the third embodiment, the flat face29Ja of the flat welding jig29J spans from the wiring part9to the protrusion33to apply load onto the same to hold down the metal substrate7around the scheduled portion, thereby to precisely apply the hold-down force to the metal substrate7or flexure5around the scheduled portion through the wiring part9and the protrusion33. The circular annular shape of the protrusion33serves as the mark for positioning the through hole29Ja of the welding jig29J.

The protrusion33has the circular annular shape that encircles the scheduled portion in the plan view and therefore the metal substrate7is held down in a region that encircles the scheduled portion. This more precisely applies the hold-down force to the metal substrate7around the scheduled portion.

FIGS. 18 to 27are plan views illustrating the first to tenth modifications of the third embodiment. The modifications are basically the same as the third embodiment and therefore the corresponding components are represented with the same reference numerals or the same reference numerals plus “K” to “U” to omit repetition of explanation.

The first to tenth modifications form protrusions circumferentially partly or discontinuously provided on a part of the intervening portion7esurrounding the scheduled portion. The protrusions are symmetrically arranged in the front-rear direction and the right-left direction.

The first modification ofFIG. 18forms gaps33Kc and33Kd based on the protrusion33ofFIG. 16to have the right and left protrusions33Ka and33Kb separated by the gaps33Kc and33Kd interposed therebetween. The protrusions33Ka and33Kb are symmetric in the front-rear direction and the right-left direction. The gaps33Kc and33Kd are arranged on respective sides in the front-rear direction or the longitudinal direction of the flexure5in the region between the right and left protrusions33Ka and33Kb, to keep the balance in the right-left direction.

The first modification easily controls the inert gas to avoid welding burning with the presence of the gaps33Kc and33Kd in comparison with the third embodiment ofFIG. 16.

The second modification ofFIG. 19forms gaps33Lc and33Ld based on the protrusion33ofFIG. 16to have the front and rear protrusions33La and33Lb separated by the gaps33Lc and33Ld interposed therebetween. The protrusions33La and33Lb are symmetric in the front-rear direction and the right-left direction. The gaps33Lc and33Ld are arranged on respective sides in the right-left direction of the flexure5in the region between the front and rear protrusions33La and33Lb, to keep the balance in the front and rear direction.

The second modification easily controls the inert gas to avoid welding burning with the presence of the gaps33Lc and33Ld in comparison with the third embodiment ofFIG. 16.

The third modification ofFIG. 20is a combination of the first and second modifications ofFIGS. 18 and 19. Namely, the third modification forms gaps33Me,33Mf,33Mg and33Mh based on the protrusion33ofFIG. 16to have the protrusions33Ma,33Mb,33Mc and33Md separated by the gaps33Me,33Mf,33Mg and33Mh. The protrusions33Ma,33Mb,33Mc and33Me are symmetric in the front-rear direction and the right-left direction.

The gaps33Me,33Mf,33Mg and33Mh are arranged between the respective interspaces between the adjacent ones of the protrusions33Ma,33Mb,33Mc and33Md so as to be symmetric in the front-rear direction and the right-left direction, to keep the balance in the front-rear direction and the right-left direction.

The third modification easily controls the inert gas to avoid welding burning with the presence of the gaps33Me,33Mf,33Mg and33Mh in comparison with the third embodiment ofFIG. 16.

The fourth modification ofFIG. 21circumferentially arranges a plurality of discrete protrusions33N around the welded spot35at regular intervals. Use protrusions33N form a circular annular shape as a whole. The circular annular shape of the protrusions33N corresponds to the protrusion33ofFIG. 16. The adjacent protrusions33N define a gap33Na therebetween.

The sectional layered structure of each one protrusion33N is the same as that of the wiring part9on each side of the protrusion33N in the right and left direction. Namely, the protrusion33N includes the base layer19N, the conductive layer21N and the cover layer23N similar to the base layer19, the conductive layer21and the cover layer23of the protrusion13ofFIG. 3.

According to the fourth modification, the base layer19N has a circular planar shape and the conductive layer21N has a circular planar shape and is formed on the base layer19N. The cover layer23N has the top wall23Na, the side wall23Nb and the flange23Nc so as to cover the conductive layer21N. The flat top face23Naa of the top wall23Na is positioned at the same height as the flat top face9aof the wiring part9.

The protrusion33N may have a different sectional shape like the protrusion13of the first embodiment. The protrusion33N may be wholly made of the same material as the base layer19N in the same way as the protrusion13. The planar shape of the protrusion33N is not limited to the circular shape and may employ a different shape such as oval, square, triangular, or rhombic shape. These may be also applied to the other modifications having the similar protrusion.

According to the fourth modification, the flat face29bof the flat welding jig29spans from the wiring part9to the protrusions33N to apply load onto the same to hold down the metal substrate7around the scheduled portion, thereby to precisely apply the hold-down force to the metal substrate7around the scheduled portion through the wiring part9and the protrusions33N.

In particular, the discrete protrusions33N independently apply the hold-down force to the metal substrate7at respective points to allow the welded spot35to be precisely formed and the inert gas to be easily controlled through the gaps33Na.

The fifth modification ofFIG. 22circumferentially arranges a plurality of discrete protrusions33P around the welded spot35at regular intervals so that the protrusions33P form a circular annular shape as a whole. The protrusions33P are located on the positions of the protrusions33N ofFIG. 21, respectively. The adjacent protrusions33P define a gap33Pa therebetween.

The planer shape of each one protrusion33P is circular and the sectional layered structure of each one protrusion33P is the same as that of the protrusion33N ofFIG. 21except for the base layer19R. The base layer19P is a circular annular shape to continuously extend over the protrusions33P.

According to the fifth modification, the protrusions33P receive the hold-down force from the flat face29bof the flat welding jig29at the time of the welding and transmit the received hold-down force through the base layer19P to the metal substrate7around the scheduled portion. This results in precisely forming the welded spot35. Further, the fifth modification easily controls the inert gas through the gaps33Pa. The base layer being the circular annular shape to continuously extend over the protrusions is applicable to the other modifications in the same way as the fifth modification.

The sixth modification ofFIG. 23is based on the fourth modification ofFIG. 21and is provided with the protrusions33Q having a linear planar shape instead of the protrusions33N having the circular planar shape. The protrusions33Q linearly extend in a radial direction and have radial ends with a semi-circular planar shape. Use protrusions33Q are circumferentially arranged around the welded spot35at regular intervals like the fourth modification. The protrusions33Q form a circular annular shape as a whole. The adjacent protrusions33Q define a gap33Qa therebetween.

According to the sixth modification, the protrusions33Q receive the hold-down force from the flat face29bof the flat welding jig29at the time of the welding and press radially-elongated regions of the metal substrate7around the scheduled portion. This results in precisely forming the welded spot35. Further, the sixth modification easily controls the inert gas through the gaps33Qa.

The seventh modification ofFIG. 24is based on the sixth modification ofFIG. 23and is provided with protrusions33Ra and33Rb alternated with each other in the circumferential direction. The protrusions33Ra face each other across the welded spot35in the front-rear direction or the right-left direction, are arranged on an annular circular region surrounding the welded spot35and are elongated in the circumferential direction to have an arc planar shape. The protrusions33Rb correspond to the protrusions33Q ofFIG. 23. The adjacent protrusions33Ra and33Rb define a gap33Rc therebetween.

According to the seventh modification, the protrusions33Ra increase the circumferential continuity of the hold-down force in comparison with the sixth modification. The seventh modification changes the control of the inert gas with the gap33Rc.

The eighth modification ofFIG. 25is based on the seventh modification ofFIG. 24and is provided with protrusions33Sa and33Sb alternated with each other in the circumferential direction. The protrusions33Sb face each other across the welded spot35in the left oblique or right oblique directions and have a circular planar shape like the protrusion33N ofFIG. 21. The protrusions33Sa correspond to the protrusions33Ra ofFIG. 24. The adjacent protrusions33Sa and33Sb define a gap33Sc therebetween.

According to the eighth modification, each one protrusion33Sb applies the hold-down force to the metal substrate7at a circumferential point between the circumferentially-elongated protrusions33Sa in comparison with the seventh modification.

The ninth modification ofFIG. 26is based on the sixth modification ofFIG. 23and is provided with protrusions33Ta and33Tb alternated with each other in the circumferential direction. The protrusions33Ta face each other across the welded spot35in the front-rear or right-left directions and have a circular planar shape like the protrusion33N ofFIG. 21. The protrusions33Tb correspond to the protrusions33Q ofFIG. 23. The adjacent protrusions33Ta and33Tb define a gap33Tc therebetween.

According to the ninth modification, each one protrusion33Ta applies the hold-down force to the metal substrate7at a circumferential point between the radially-elongated protrusions33Tb in comparison with the sixth modification.

The tenth modification ofFIG. 27is based on the fourth modification ofFIG. 21and is provided with protrusions33Ua and33Ub. The protrusions33Ua are circumferentially arranged at regular intervals so as to outline an inner circumference around the welded spot35and the protrusions33Ub are circumferentially arranged at regular intervals so as to outline an outer circumference concentric with the inner circumference. The protrusions33Ua are the same as the protrusions33N ofFIG. 21. The protrusions33Ub have the same planar shape as the protrusions33N and are shifted outward in the radial direction relative to the protrusions33Ua. Each one protrusion33Ub is arranged circumferentially between the adjacent protrusions33Ua. The adjacent protrusions33Ua and the adjacent protrusions33Ub define a gap33Uc therebetween.

According to the tenth modification, the protrusions33Ua and the protrusions33Ub apply the hold-down force to the metal substrate7at double radially inner and outer points. The tenth modification changes the control of the inert gas with the gap33Uc.