JP2013222480A - Substrate for suspension, suspension, head-attached suspension, combinational body of head-attached suspension and external connection substrate, and hard disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for suspension capable of reducing wearing of a bonding tool used for attaching an external connection substrate, and improving bonding reliability with external terminals of the external connection substrate.SOLUTION: A substrate 1 for suspension comprises an insulation layer 10, a metal supporting layer 20, and a wiring layer 30. The wiring layer 30 includes a plurality of wiring 31, and a plurality of connection terminals 33 each capable of being ultrasonically bonded to an external terminal 132 of an external connection substrate 131 using a bonding tool 60. The insulation layer 10 and the metal supporting layer 20 are provided with openings 70 for exposing the connection terminals 33. Each of the connection terminals 33 includes a tool surface 35 pressed by the bonding tool 60 and a bonding surface 36 ultrasonically bonded to the external terminal 132 of the external connection substrate 131. The surface roughness of the tool surface 35 of each connection terminal 33 is smaller than that of the bonding surface 36.

Description

  The present invention relates to a suspension board, a suspension, a suspension with a head, a combination of a suspension with a head and an external connection board, and a hard disk drive. In addition, the present invention relates to a suspension substrate, a suspension, a suspension with a head, a combination of a suspension with a head and an external connection substrate, and a hard disk drive that can improve the reliability of bonding with an external terminal of the external connection substrate.

  In general, a hard disk drive (HDD) includes a suspension substrate on which a magnetic head slider (hereinafter simply referred to as a head slider) for writing and reading data to and from a disk on which data is stored is mounted. Such a suspension substrate is formed so as to extend from a head region on which the head slider is mounted to a tail region to which an external connection substrate (FPC substrate, flexible printed circuit board) is joined. And a wiring layer having a plurality of wirings stacked on the support layer with an insulating layer interposed therebetween. Data is written to or read from the disk by passing an electric signal through each wiring.

  As described above, the FPC board is mounted on the tail region of the suspension board. That is, in the tail region of the suspension substrate, flying leads (connection terminals) connected to the respective wirings are provided, and each flying lead has a substantially rectangular opening formed in the metal support layer and the insulating layer. Are exposed in parallel, and are ultrasonically bonded to the FPC terminal of the FPC board through this opening (see, for example, Patent Documents 1 and 2).

JP 2007-173362 A JP 2007-173363 A

  Among these, in Patent Document 1, a bonding tool having a roller supported so as to be freely rollable is moved in a direction across the flying leads arranged in parallel at intervals, and the flying lead and the substrate pad are ultrasonically moved. It is joined. However, in this case, the roller rolls on the flying leads arranged at intervals. For this reason, there is a problem that there is a concern about wear or damage of the roller. Patent Document 2 describes that a plurality of flying leads are pressed at a time to ultrasonically bond the flying leads and the substrate pad, but there is no description regarding wear of the bonding tool.

  The present invention has been made in consideration of such points, and reduces the wear of the bonding tool used when mounting the external connection board, and improves the bonding reliability of the external connection board with the external terminals. It is an object of the present invention to provide a suspension substrate, a suspension, a suspension with a head, a combination of a suspension with a head and an external connection substrate, and a hard disk drive.

  The present invention provides a suspension substrate having a tail region attached to an external connection substrate, provided with an insulating layer, a metal support layer provided on one surface of the insulating layer, and the other surface of the insulating layer. A plurality of wirings, and a plurality of connection terminals provided in the tail region and connected to each of the wirings and capable of being ultrasonically bonded to the external terminals of the external connection board using a bonding tool. The wiring layer, and the insulating layer and the metal support layer are provided with openings for exposing the connection terminals, the connection terminals being pressed by the bonding tool, A bonding surface ultrasonically bonded to the external terminal of the external connection board, and the surface roughness of the tool surface of the connection terminal is smaller than the surface roughness of the bonding surface To provide a substrate for scan pension.

  In the suspension substrate described above, the tool surface of the connection terminal is disposed on the insulating layer side, and the joint surface of the connection terminal is disposed on the opposite side of the insulating layer side, It is preferable that the opening is configured so that the bonding tool can be inserted therein.

  In the suspension substrate described above, it is preferable that a thickness of a portion of the protective layer covering the wiring is thinner than a total thickness of the metal support layer and the insulating layer.

  In the suspension substrate described above, it is preferable that the tool surface of the connection terminal has a surface roughness with an arithmetic average roughness of 0.06 μm or less.

  In the suspension substrate described above, it is preferable that the joint surface of the connection terminal has a surface roughness with an arithmetic average roughness exceeding 0.06 μm.

  Further, in the suspension substrate described above, a tool surface side plating layer is provided on the tool surface of the connection terminal, a bonding surface side plating layer is provided on the bonding surface of the connection terminal, and the tool surface side is provided. The surface roughness of the plating layer is preferably smaller than the surface roughness of the bonding surface side plating layer.

  In the suspension substrate described above, the opening includes an insulating opening provided in the insulating layer and a metal opening provided in the metal support layer, and the metal opening includes the metal opening. The length along the longitudinal direction of the connection terminal is preferably longer than the length along the longitudinal direction of the connection terminal of the insulating opening.

  In the suspension substrate described above, the insulating layer further includes a protective layer provided on a surface of the insulating layer on the wiring layer side to cover the wiring, and the protective layer has a protective opening that exposes the connection terminal. It is preferable that the length of the protective opening along the longitudinal direction of the connection terminal is longer than the length of the insulating opening along the longitudinal direction of the connection terminal.

  The present invention provides a suspension comprising: a base plate; and the above-described suspension substrate attached to the base plate via a load beam.

  The present invention provides a suspension with a head, comprising the above-described suspension and the head slider mounted on the suspension.

  The present invention includes the above suspension with a head and the external connection board mounted on the tail region of the suspension board, and the external connection board is formed on the joint surface of the connection terminal of the suspension board. A combination of a suspension with a head and an external connection board, wherein the external terminals are ultrasonically bonded.

  The present invention provides a hard disk drive including the above-described suspension with a head.

  ADVANTAGE OF THE INVENTION According to this invention, while reducing the abrasion of the bonding tool used when mounting | wearing with an external connection board | substrate, joining reliability with the external terminal of an external connection board | substrate can be improved.

FIG. 1 is a plan view showing an example of a suspension substrate according to an embodiment of the present invention. FIG. 2 is a back view showing a tail region in the suspension substrate according to the embodiment of the present invention. 3 is a cross-sectional view taken along line XX in FIG. FIG. 4 is a plan view showing an example of the suspension in the embodiment of the present invention. FIG. 5 is a plan view showing an example of the suspension with a head according to the embodiment of the present invention. FIG. 6 is a plan view showing an example of a combination of a suspension with a head and an external connection board in the embodiment of the present invention. FIG. 7 is a view showing a cross section corresponding to the line XX of FIG. 2 in the combination of the suspension with head and the external connection board in the embodiment of the present invention. FIG. 8 is a perspective view showing an example of the hard disk drive in the embodiment of the present invention. FIGS. 9A to 9I are diagrams showing a method for manufacturing a suspension substrate in the embodiment of the present invention. FIGS. 10A and 10B are diagrams illustrating a method of joining a flying lead to an FPC terminal in the embodiment of the present invention. FIG. 11 is a back view for explaining a method of joining a flying lead to an FPC terminal in the embodiment of the present invention. FIG. 12 is a diagram showing the relationship between the surface roughness (Ra) of the joining surface of the flying lead and the joining strength (tensile strength) between the flying lead and the FPC terminal.

  A suspension substrate, a suspension, a suspension with a head, a combination of a suspension with a head and an external connection substrate, and a hard disk drive will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual ones.

  As shown in FIG. 1, the suspension board 1 is mounted with an FPC board (external connection board, flexible printed board, see FIG. 6) 131 from a head region 2 where a head slider (see FIG. 5) 112 described later is mounted. The tail region 3 is formed so as to extend. In the present embodiment, the head region 2 means a region close to the head terminal 32 connected to the mounted head slider 112, and the tail region 3 is a flying lead 33 described later connected to the FPC board 131. It means the area close to.

  As shown in FIGS. 1 to 3, the suspension substrate 1 includes an insulating layer 10, a metal support layer 20 provided on one surface of the insulating layer 10, and a wiring provided on the other surface of the insulating layer 10. And a layer 30. The wiring layer 30 includes a plurality of wirings 31 including a reading wiring and a writing wiring, and flying leads (connection terminals) 33 provided in the tail region 3 and connected to each wiring 31. The flying lead 33 is configured to be capable of ultrasonic bonding to the FPC terminal (external terminal) 132 of the FPC board 131 using the bonding tool 60 (see FIG. 10). Further, a test line 34 is connected to the flying lead 33 so that a continuity test of each wiring 31 can be performed at the time of manufacturing the suspension substrate 1. In the head region 2, head terminals 32 connected to the respective wirings 31 are provided.

  As shown in FIG. 3, a metal thin film layer 50 formed by sputtering is interposed between the insulating layer 10 and the wiring layer 30. The metal thin film layer 50 is formed of nickel (Ni), chromium (Cr), or an alloy thereof (which may include copper (Cu)), and adhesion between the insulating layer 10 and the wiring layer 30. Has improved. The thickness of the metal thin film layer 50 is preferably about 300 nm, for example.

  As shown in FIGS. 2 and 3, the insulating layer 10 and the metal support layer 20 are provided with openings 70 through which the flying leads 33 are exposed. The opening 70 is formed in a substantially rectangular shape, and has an insulating opening 11 provided in the insulating layer 10 and a metal opening 21 provided in the metal support layer 20. The length of the metal opening 21 along the longitudinal direction of the flying lead 33 (dimension A in FIG. 3) is longer than the length of the insulating opening 11 along the longitudinal direction of the flying lead 33 (dimension B in FIG. 3). It has become.

  As shown in FIG. 2, the flying leads 33 are formed in an elongated rectangular shape, and are arranged in parallel on the opening 70. That is, the flying leads 33 are arranged in parallel along a direction orthogonal to the longitudinal direction. Although FIG. 2 shows an example in which six flying leads 33 are provided, the number of flying leads 33 is not limited to this. In FIG. 2, the flying lead 33 is shown not by a cross section but by a back surface, but the flying lead 33 is hatched for the purpose of clarity.

  As shown in FIG. 3, the flying lead 33 includes a tool surface 35 that is pressed by the bonding tool 60 and a bonding surface 36 that is bonded to the FPC terminal 132 of the FPC board 131. In the present embodiment, as shown in FIGS. 3, 7 and 10, the tool surface 35 of the flying lead 33 is disposed on the insulating layer 10 side, and the metal opening 21 and the insulating material described above are insulated. The opening 11 is exposed. The metal opening 21 and the insulating opening 11 are configured so that the bonding tool 60 can be inserted. When the FPC board 131 is mounted on the suspension substrate 1, the bonding tool 60 is insulated from the metal opening 21 and the insulating opening 11. The tool surface 35 of the flying lead 33 is pressed by being inserted into the opening 11. The joining surface 36 of the flying lead 33 is disposed on the side opposite to the insulating layer 10 side and exposed by a protective opening 41 described later.

  The surface roughness of the tool surface 35 of the flying lead 33 is smaller than the surface roughness of the joint surface 36. For example, the tool surface 35 of the flying lead 33 preferably has a surface roughness with an arithmetic average roughness (Ra) defined by JIS B0601-2001 of 0.06 μm or less. The joining surface 36 preferably has a surface roughness with an arithmetic average roughness exceeding 0.06 μm.

  As shown in FIG. 3, a tool surface side plating layer 37 is provided on the tool surface 35 of the flying lead 33, and a bonding surface side plating layer 38 is provided on the bonding surface 36 of the flying lead 33. These plating layers 36 and 37 are formed by sequentially performing nickel (Ni) plating and gold (Au) plating, and prevent the tool surface 35 and the joint surface 36 of the flying lead 33 from corroding. ing. The thickness of such plating layers 36 and 37 is preferably 0.1 μm to 4.0 μm. Further, since the surface roughness of the tool surface 35 of the flying lead 33 is smaller than the surface roughness of the bonding surface 36 as described above, the surface roughness of the tool surface side plating layer 37 is equal to the bonding surface side plating layer 38. It is smaller than the surface roughness. That is, the surface roughness of the tool surface side plating layer 37 has a surface roughness substantially equal to the surface roughness of the tool surface 35 of the flying lead 33, and the surface roughness of the bonding surface side plating layer 38 is the flying lead 33. The joint surface 36 has a surface roughness substantially equal to the surface roughness.

  Further, as shown in FIG. 3, the surface on the wiring layer 30 side of the insulating layer 10 covers the wiring 31 and the test line 34 of the wiring layer 30, and protection for preventing corrosion of the wiring 31 and the test line 34. A layer 40 is provided. The protective layer 40 is provided with a protective opening 41 that exposes the flying lead 33. The length of the protective opening 41 along the longitudinal direction of the flying lead 33 (dimension C in FIG. 3) is longer than the length of the insulating opening 11 along the longitudinal direction of the flying lead 33 (dimension B in FIG. 3). Yes. On the other hand, the dimension C of the protective opening 41 is smaller than the dimension A of the metal opening 21. Further, the thickness of the portion of the protective layer 40 that covers the wiring 31 (dimension D in FIG. 3) is thinner than the total thickness of the metal support layer 20 and the insulating layer 10. In FIG. 1, the protective layer 40 is omitted for the sake of clarity.

  Next, each component will be described in detail.

  The material of the insulating layer 10 is not particularly limited as long as it is a material having a desired insulating property. For example, it is preferable to use polyimide (PI). Note that the material of the insulating layer 10 can be a photosensitive material or a non-photosensitive material. The thickness of the insulating layer 10 is preferably 5 μm to 30 μm, particularly 8 μm to 10 μm. As a result, it is possible to ensure the insulation performance between the metal support layer 20 and each wiring 31 and to prevent the rigidity of the suspension substrate 1 as a whole from being lost.

  The wiring 31 is configured as a conductor for transmitting an electrical signal. The material of the wiring 31 is not particularly limited as long as it has a desired conductivity, but copper (Cu) is used. Is preferred. In addition to copper, any material having electrical characteristics similar to pure copper can be used. Here, it is preferable that the thickness of the wiring 31 is, for example, 1 μm to 18 μm, particularly 9 μm to 12 μm. As a result, the transmission characteristics of the wiring 31 can be ensured, and the loss of flexibility of the suspension substrate 1 as a whole can be prevented. The head terminal 32, flying lead 33, and test line 34 are formed of the same material and the same thickness as the wiring 31.

  The material of the metal support layer 20 is not particularly limited as long as it has desired conductivity, elasticity, and strength. For example, stainless steel, aluminum, beryllium copper, or other copper alloys are used. It is preferable to use stainless steel. The thickness of the metal support layer 20 can be 10 μm to 30 μm, especially 15 μm to 20 μm. As a result, the conductivity, rigidity, and elasticity of the metal support layer 20 can be ensured.

  As a material of the protective layer 40, it is preferable to use a resin material, for example, polyimide. The material of the protective layer 40 can be a photosensitive material or a non-photosensitive material. In addition, the thickness of the portion of the protective layer 40 covering the wiring 31 (D dimension in FIG. 3) is thinner than the total thickness of the insulating layer 10 and the metal support layer 20 as described above, particularly 4 μm. It is preferable to be set to ˜6 μm. As a result, as will be described later, the insulation performance of the wiring 31 can be ensured even when the FPC board 131 is attached to the tail region 3, and the wiring 31 is prevented from being corroded. It is possible to prevent the rigidity of the suspension substrate 1 as a whole from being lost.

  Next, the suspension 101 in the present embodiment will be described with reference to FIG. The suspension 101 shown in FIG. 4 includes a base plate 102, a load beam 103 that is attached on the base plate 102 and holds the metal support layer 20 of the suspension substrate 1, and the suspension substrate 1 that is attached to the load beam 103. I have.

  Next, the suspension with head 111 in the present embodiment will be described with reference to FIG. A suspension with head 111 shown in FIG. 5 includes the suspension 101 described above and a head slider 112 mounted on the head region 2 of the suspension substrate 1.

  Next, referring to FIG. 6 and FIG. 7, the combination 141 of the suspension with a head and the FPC board in this embodiment will be described. The combined body 141 includes a suspension 111 with a head and an FPC board 131 mounted on the tail region 3 of the suspension board 1. Among these, the FPC board 131 is disposed on the protective layer 40 side of the suspension board 1 as shown in FIG. 7, and the flying leads 33 of the suspension board 1 are on the FPC terminal 132 side of the FPC board 131. The FPC terminal 132 is ultrasonically bonded to the bonding surface 36 of the flying lead 33 through the bonding surface side plating layer 37 by being pressed. The FPC board 131 includes an insulating plate 133, the above-described FPC terminal 132 provided on the insulating plate 133, and a cover layer 134 that covers a part of the FPC terminal 132. Among these, the FPC terminal 132 is subjected to nickel plating and gold plating in this order. Further, the protective layer 40 of the suspension substrate 1 is in contact with the cover layer 134.

  Next, the hard disk drive 121 in the present embodiment will be described with reference to FIG. A hard disk drive 121 shown in FIG. 8 includes a case 122, a disk 123 that is rotatably attached to the case 122 and stores data, a spindle motor 124 that rotates the disk 123, the above-described suspension with head and FPC. A combination body 141 with a substrate. Of these, the suspension with head 111 is provided so as to be close to the disk 123 while maintaining a desired flying height, and the head slider 112 mounted on the suspension with head 111 writes and reads data to and from the disk 123. Is supposed to do. The suspension with head 111 is attached to the case 122 so as to be movable. A voice coil motor 125 that moves the head slider 112 of the suspension with head 111 along the disk 123 is attached to the case 122. The suspension with head 111 is attached to the boil coil motor 125 via the arm 126. ing. Further, the FPC board 131 mounted on the suspension with head 111 is connected to a control unit (not shown) that controls the hard disk drive 121. As a result, an electric signal is transmitted between the control unit and the head slider 112 via the suspension substrate 1 and the FPC substrate 131.

  Next, the operation of the present embodiment having such a configuration will be described. Here, first, a method for manufacturing the suspension substrate 1 by the subtractive method will be described. The suspension substrate 1 may be manufactured by an additive method.

  First, the laminated body 80 which has the insulating layer 10, the metal support layer 20 provided in the one surface of the insulating layer 10, and the wiring layer 30 provided in the other surface of the insulating layer 10 is prepared.

  In this case, first, the metal support layer 20 is prepared (see FIG. 9A). Subsequently, a liquid non-photosensitive material is applied and cured on the metal support layer 20 (the lower surface in FIG. 9) to form the insulating layer 10 (see FIG. 9B). Next, the metal thin film layer 50 is formed on the insulating layer 10 by sputtering (see FIG. 9C). Thereafter, the wiring layer 30 is formed on the metal thin film layer 50 by electrolytic copper plating (see FIG. 9D). At this time, since the wiring layer 30 is formed on the insulating layer 10 via the metal thin film layer 50, the surface roughness of the tool surface 35 on the insulating layer 10 side of the flying lead 33 obtained by etching is reduced. That is, as described above, since the insulating layer 10 is formed by applying a liquid non-photosensitive material, the surface roughness of the insulating layer 10 is small, and the surface of the insulating layer 10 is formed smoothly. A sufficiently thin metal thin film layer 50 is formed on the insulating layer 10. For this reason, reflecting the smooth surface of the insulating layer 10, the surface roughness of the tool surface 35 of the flying lead 33 can be reduced. In this way, a laminate 80 having the insulating layer 10, the metal support layer 20, and the wiring layer 30 is obtained.

  Subsequently, a plurality of wirings 31 and flying leads 33 are formed from the wiring layer 30 of the stacked body 80, and a metal opening 21 is formed in the metal support layer 20 (see FIG. 9E). In this case, a patterned resist (not shown) is formed on the wiring layer 30 and the metal support layer 20 by the photofabrication technique, and the metal is formed from the opening of the resist by a corrosive liquid such as a ferric chloride aqueous solution. The thin film layer 50, the wiring layer 30, and the metal support layer 20 are etched. Thus, the wiring 31 and the flying lead 33 having a desired shape are formed, and the metal opening 21 is formed. At this time, the head terminal 32 and the test line 34 are also formed. Thereafter, the resist is removed.

  Next, the protective layer 40 including the protective opening 41 is formed on the insulating layer 10 (see FIG. 9F). In this case, first, a protective layer 40 made of a non-photosensitive material is formed on the insulating layer 10, and a patterned resist is formed on the protective layer 40. Next, the protective layer 40 is etched from the opening of the patterned resist with an etching solution such as an organic alkaline solution. As a result, a protective opening 41 is formed in the protective layer 40. The protective layer 40 may be etched by plasma etching. Thereafter, the resist is removed.

  Next, the insulating opening 11 is formed in the insulating layer 10, and the outer shape of the insulating layer 10 is processed into a desired shape (see FIG. 9G). In this case, first, a patterned resist is formed, and the insulating layer 10 is etched from an opening of the resist with an etching solution such as an organic alkaline solution, whereby an insulating opening 11 is formed in the insulating layer 10 and the insulating layer 10 is formed. The outer shape is processed. Thereafter, the resist is removed. Note that the etching of the insulating layer 10 can also be performed by plasma etching.

  Subsequently, the portion of the metal thin film layer 50 exposed to the insulating opening 11 is removed by plasma etching (see FIG. 9H). As a result, the tool surface 35 of the flying lead 33 is exposed through the metal opening 21 and the insulating opening 11.

  Next, the plating 31 is formed by sequentially performing nickel plating and gold plating on the flying lead 33 using the wiring 31 as a power feeding layer for plating (see FIG. 9I). That is, the tool surface side plating layer 37 is formed on the tool surface 35 of the flying lead 33, and the bonding surface side plating layer 38 is formed on the bonding surface 36. At this time, the head terminal 32 is also plated. The tool surface side plating layer 37 may be formed by gloss plating. In this case, the bonding surface 36 is preferably protected with a film or the like. Thereby, the surface roughness of the tool surface side plating layer 37 can be further reduced. Moreover, you may form the joint surface side plating layer 38 by roughening plating (electrolytic plating, electroless plating). In this case, the tool surface 35 is preferably protected with a film or the like. Thereby, the surface roughness of the bonding surface side plating layer 38 can be increased.

  Next, the metal support layer 20 is trimmed into a desired shape. In this case, a patterned resist is formed on the metal support layer 20, and the metal support layer 20 is etched from the opening of the resist with a corrosive liquid such as a ferric chloride aqueous solution, so that the metal support layer 20 is trimmed. The Thereafter, the resist is removed.

  In this way, the suspension substrate 1 shown in FIG. 1 is obtained.

  The base plate 102 and the load beam 103 are attached to the obtained suspension substrate 1 by welding to obtain the suspension 101 according to the present embodiment. A head slider 112 is mounted on the head region 2 of the suspension 101, and the suspension with head 111 shown in FIG. 5 is obtained.

  The FPC board 131 is attached to the suspension board 1 of the suspension with head 111 shown in FIG. 5, and the combined body 141 of the suspension with head and the FPC board shown in FIG. 6 is obtained.

  In this case, first, the FPC terminal 132 of the FPC board 131 is aligned so as to face the joint surface 36 of the flying lead 33 of the suspension board 1. Subsequently, as shown in FIG. 10A, the bonding tool 60 is inserted into the metal opening 21 and the insulating opening 11 while being ultrasonically vibrated, and the tool surface side of the flying lead 33 is moved to the tool surface side. Abutting through the plating layer 37, the flying lead 33 is pressed downward (on the FPC terminal 132 side). At this time, since the flying lead 33 has flexibility, it is deformed so as to receive a pressing force from the bonding tool 60 and to be pushed into the FPC terminal 132 side. As shown in FIG. 11, the bonding tool 60 has a rectangular cross section in which six flying leads 33 can be ultrasonically bonded at one time, and the longitudinal direction thereof is along the parallel direction of the flying leads 33. So that it is pressed against the flying lead 33.

  Next, when the bonding tool 60 presses the flying lead 33, the flying lead 33 comes into contact with the FPC terminal 132 through the bonding surface side plating layer 38 as shown in FIG. Thereafter, ultrasonic vibration is propagated to the interface between the bonding surface side plating layer 38 and the FPC terminal 132, and the flying lead 33 and the FPC terminal 132 are ultrasonically bonded. In this case, the gold on the bonding surface side plating layer 38 and the gold plated on the surface of the FPC terminal 132 are rubbed together to form a metal bond.

  In this way, the FPC board 131 is mounted on the tail region 3 of the suspension board 1, and the combined body 141 of the suspension with head and the FPC board is obtained.

  Thereafter, the combined body 141 of the suspension with head and the FPC board is attached to the arm 126, and the hard disk drive 121 shown in FIG. 8 is obtained.

  When data is written and read in the hard disk drive 121 shown in FIG. 8, the head slider 112 of the suspension with head 111 is moved along the disk 123 by the voice coil motor 125 and is rotated by the spindle motor 124. Keep close to the desired flying height. As a result, data is exchanged between the head slider 112 and the disk 123. During this time, an electrical signal is transmitted between the control unit and the head slider 112 via the suspension substrate 1 and the FPC substrate 131. More specifically, the electrical signal is transmitted between the suspension board 1 and the FPC board 131 via the flying lead 33 of the suspension board 1 and the FPC terminal 132 of the FPC board 131. In the suspension substrate 1, an electrical signal is transmitted through each wiring 31 connected to the flying lead 33 and the head terminal 32.

  As described above, according to the present embodiment, the surface roughness of the tool surface 35 of the flying lead 33 pressed by the bonding tool 60 is smaller than the surface roughness of the bonding surface 36 bonded to the FPC terminal 132 of the FPC board 131. It has become. As a result, the surface roughness of the tool surface side plating layer 37 formed on the tool surface 35 can be made smaller than the surface roughness of the bonding surface side plating layer 38 formed on the bonding surface 36. Further, it is possible to prevent the tool surface side plating layer 37 from being worn by pressing. For this reason, wear of the bonding tool 60 can be reduced and the life of the bonding tool 60 can be extended. Further, since the surface roughness of the tool surface side plating layer 37 is small, the pressing force of the bonding tool 60 can be uniformly transmitted to the tool surface side plating layer 37. For this reason, the bonding reliability between the flying lead 33 and the FPC terminal 132 can be improved.

  Here, Table 1 shows the relationship between the surface roughness of the tool surface 35 of the flying lead 33 and the wear of the bonding tool 60. As shown in Table 1, when the surface roughness of the tool surface 35 of the flying lead 33 is reduced, the wear of the bonding tool 60 is reduced. In particular, the arithmetic average roughness (Ra) of the tool surface 35 is 0. It can be seen that when the thickness is 0.06 μm or less, the wear of the bonding tool 60 is further reduced. For this reason, since the tool surface 35 of the flying lead 33 has an arithmetic average roughness of 0.06 μm or less, the wear of the bonding tool 60 can be further reduced and the life of the bonding tool 60 can be further extended. . In Table 1, “Δ” means that the wear of the bonding tool 60 is reduced compared to “×”, and “◯” means that the wear of the bonding tool 60 is further reduced than “Δ”. ing.

  Further, according to the present embodiment, the surface roughness of the joining surface 36 of the flying lead 33 is larger than the surface roughness of the tool surface 35. Thereby, the surface roughness of the bonding surface side plating layer 38 formed on the bonding surface 36 can be made larger than the surface roughness of the tool surface side plating layer 37 formed on the tool surface 35, and the bonding surface side plating can be performed. Ultrasonic vibrations can be concentrated on the minute protrusions formed on the surface of the layer 38, and the protrusions can be bitten into the minute recesses formed on the surface of the FPC terminal 132. For this reason, the bonding strength between the flying lead 33 and the FPC terminal 132 can be increased, and the bonding reliability between the flying lead 33 and the FPC terminal 132 can be improved.

Here, FIG. 12 shows the relationship between the surface roughness of the joining surface 36 of the flying lead 33 and the joining strength between the flying lead 33 and the FPC terminal 132 (tensile strength in a direction substantially perpendicular to the joining surface 36). As shown in FIG. 12, when the surface roughness of the joining surface 36 of the flying lead 33 is increased, the joining strength between the flying lead 33 and the FPC terminal 132 is increased. As a result, when the arithmetic average roughness of the joint surface 36 is 0.06 μm, the joint strength between the flying lead 33 and the FPC terminal 132 is 80 N / cm ^2, and sufficient reliability can be imparted to the bonding between the flying lead 33 and the FPC terminal 132. For this reason, since the joining surface 36 of the flying lead 33 has a surface roughness exceeding 0.06 μm, the joining strength between the flying lead 33 and the FPC terminal 132 can be increased. It is possible to further improve the bonding reliability.

  Further, according to the present embodiment, the flying lead 33 is formed by electrolytic copper plating on the insulating layer 10 through the metal thin film layer 50 formed by sputtering, and the metal thin film layer 50 is removed by plasma etching. ing. That is, the tool surface 35 on the insulating layer 10 side of the flying lead 33 is formed on the smooth surface of the insulating layer 10 via the thin metal thin film layer 50. Thus, the surface roughness of the tool surface 35 of the flying lead 33 can be reduced reflecting the smooth surface of the insulating layer 10.

  Further, according to the present embodiment, the length of the metal opening 21 along the longitudinal direction of the flying lead 33 is longer than the length of the insulating opening 11 along the longitudinal direction of the flying lead 33. This can prevent the bonding tool 60 from interfering with the metal support layer 20. Further, the peripheral edge of the metal opening 21 can be separated from the central part in the longitudinal direction of the flying lead 33 rather than the peripheral edge of the insulating opening 11, and stress applied to the flying lead 33 bonded to the FPC terminal 132 can be reduced. it can. For this reason, it is possible to prevent the flying lead 33 from being disconnected, and to improve the bonding reliability between the flying lead 33 and the FPC terminal 132.

  Further, according to the present embodiment, the length of the protective opening 41 along the longitudinal direction of the flying lead 33 is longer than the length of the insulating opening 11 along the longitudinal direction of the flying lead 33. Accordingly, the peripheral edge of the protective opening 41 can be separated from the central part in the longitudinal direction of the flying lead 33 rather than the peripheral edge of the insulating opening 11, and the stress applied to the flying lead 33 bonded to the FPC terminal 132 is reduced. be able to. For this reason, it is possible to prevent the flying lead 33 from being disconnected, and to improve the bonding reliability between the flying lead 33 and the FPC terminal 132.

  In addition, according to the present embodiment, the joining surface 36 of the flying lead 33 is disposed on the protective layer 40 side, and the thickness of the portion of the protective layer 40 that covers the wiring 31 is the metal support layer 20 and the insulating layer 10. It is thinner than the total thickness. As a result, the amount of pressing of the flying lead 33 into the FPC terminal 132 (dimension E in FIG. 10B) can be reduced, and the stress applied to the flying lead 33 joined to the FPC terminal 132 can be reduced. it can. For this reason, it is possible to prevent the flying lead 33 from being disconnected, and to improve the bonding reliability between the flying lead 33 and the FPC terminal 132. In particular, when the joint surface 36 of the flying lead 33 is disposed on the insulating layer 10 side, the amount of pushing of the flying lead 33 is the sum of the metal support layer 20, the insulating layer 10, and the cover layer 134 of the FPC board 131. Although it corresponds to the thickness, according to the present embodiment, since the joint surface 36 of the flying lead 33 is disposed on the protective layer 40 side, the pushing amount of the flying lead 33 is set to the protective layer 40 and the FPC board 131. This corresponds to the total thickness of the cover layer 134. For this reason, the pushing amount of the flying lead 33 for joining to the FPC terminal 132 can be reduced.

  In the present embodiment, in order to make the surface roughness of the tool surface 35 of the flying lead 33 smaller than the surface roughness of the bonding surface 36, the insulating layer 10 is provided with a metal thin film layer 50 formed by sputtering. The example in which the flying lead 33 is formed by electrolytic copper plating and the metal thin film layer 50 is removed by plasma etching has been described. However, the present invention is not limited to this, and the surface roughness of the tool surface 35 of the flying lead 33 can be made smaller than the surface roughness of the joining surface 36 by any method. For example, in the case where the wiring layer 30 is formed on the insulating layer 10 using an adhesive to form the flying lead 33, the bonding surface 36 is protected with a film or the like, and the tool surface 35 is treated with an acid chemical. Thus, the surface roughness of the tool surface 35 can be made smaller than the surface roughness of the bonding surface 36 by cutting the surface (chemical polishing, for example, see JP 2009-057624 A).

  In the present embodiment, the bonding surface 36 of the flying lead 33 may be further roughened by, for example, wet etching. As a result, the bonding reliability between the flying lead 33 and the FPC terminal 132 can be further improved.

  In the present embodiment, the example in which the tool surface 35 of the flying lead 33 is disposed on the insulating layer 10 side and the bonding surface 36 is disposed on the protective layer 40 side has been described. However, the present invention is not limited to this, and the tool surface 35 of the flying lead 33 may be disposed on the protective layer 40 side, and the bonding surface 36 may be disposed on the insulating layer 10 side. In this case, for example, the tool surface 35 is chemically polished as described above, so that the surface roughness of the tool surface 35 can be made smaller than the surface roughness of the bonding surface 36, thereby reducing wear of the bonding tool 60. In addition, the bonding reliability between the flying lead 33 and the FPC terminal 132 can be further improved. Further, in this case, the surface of the portion corresponding to the flying lead 33 of the insulating layer 10 is roughened in advance before the step of forming the metal thin film layer 50 (see FIG. 9C). The surface roughness of the joint surface 36 can be increased.

  The length of the metal opening 21 along the longitudinal direction of the flying lead 33, the length of the insulating opening 11 along the longitudinal direction of the flying lead 33, and the length of the protective opening 41 along the longitudinal direction of the flying lead 33 are The relationship in the present embodiment described above is not limited. Furthermore, the arithmetic average roughness of the tool surface 35 and the joint surface 36 of the flying lead 33 is not limited to the numerical range described above. That is, if the surface roughness of the tool surface 35 of the flying lead 33 is smaller than the surface roughness of the bonding surface 36, the wear of the bonding tool 60 is reduced and the bonding reliability between the FPC terminal 132 and the flying lead 33 is reduced. Can be improved.

  As described above, the embodiment of the present invention has been described in detail. However, the suspension substrate, the suspension, the suspension with the head, the combination of the suspension with the head and the external connection substrate, and the hard disk drive according to the present invention are the same as the above embodiments. It is not limited at all, and various modifications can be made without departing from the spirit of the present invention.

  The surface roughness of the tool surface 35 and the surface roughness of the joint surface 36 of the flying lead 33 obtained by using the method for manufacturing the suspension substrate 1 according to the embodiment of the present invention described above were measured. The results are shown in Table 2.

  According to Table 2, the surface roughness of the tool surface 35 of the flying lead 33 is smaller than the surface roughness of the joint surface 36, and the tool surface 35 has a surface roughness with an arithmetic average roughness of 0.06 μm or less. It was confirmed that the joint surface 36 had a surface roughness with an arithmetic average roughness exceeding 0.06 μm. In this case, the wear of the bonding tool 60 can be reliably reduced, and the bonding reliability between the flying lead 33 and the FPC terminal 132 can be reliably improved.

DESCRIPTION OF SYMBOLS 1 Substrate for suspension 2 Head region 3 Tail region 10 Insulating layer 11 Insulating opening 20 Metal support layer 21 Metal opening 30 Wiring layer 31 Wiring 32 Head terminal 33 Flying lead 34 Test line 35 Tool surface 36 Joining surface 37 Tool surface side plating Layer 38 Bonding surface side plating layer 40 Protective layer 41 Protective opening 50 Metal thin film layer 60 Bonding tool 70 Opening 80 Laminated body 101 Suspension 102 Base plate 103 Load beam 111 Suspension with head 112 Head slider 121 Hard disk drive 122 Case 123 Disk 124 Spindle Motor 125 Voice coil motor 126 Arm 131 FPC board 132 FPC terminal 133 Insulating plate 134 Cover layer 141 Assembly

Claims (12)

In the suspension board having a tail region attached to the external connection board,
An insulating layer;
A metal support layer provided on one surface of the insulating layer;
A wiring layer provided on the other surface of the insulating layer, the wiring layer being provided in the tail region and connected to each of the wirings, and connected to each of the wirings by using a bonding tool. A plurality of connection terminals capable of ultrasonic bonding, and the wiring layer having,
The insulating layer and the metal support layer are provided with openings that expose the connection terminals,
The connection terminal has a tool surface pressed against the bonding tool, and a bonding surface ultrasonically bonded to the external terminal of the external connection substrate,
The suspension substrate according to claim 1, wherein a surface roughness of the tool surface of the connection terminal is smaller than a surface roughness of the joint surface. The tool surface of the connection terminal is disposed on the insulating layer side,
The joint surface of the connection terminal is disposed on the side opposite to the insulating layer side,
The suspension substrate according to claim 1, wherein the opening is configured so that the bonding tool can be inserted therein.   3. The suspension substrate according to claim 1, wherein a thickness of a portion of the protective layer covering the wiring is thinner than a total thickness of the metal support layer and the insulating layer.   4. The suspension substrate according to claim 1, wherein the tool surface of the connection terminal has a surface roughness with an arithmetic average roughness of 0.06 μm or less. 5.   5. The suspension substrate according to claim 1, wherein the joint surface of the connection terminal has a surface roughness with an arithmetic average roughness exceeding 0.06 μm. A tool surface side plating layer is provided on the tool surface of the connection terminal,
A joining surface side plating layer is provided on the joining surface of the connection terminal,
The suspension substrate according to any one of claims 1 to 5, wherein the surface roughness of the tool surface side plating layer is smaller than the surface roughness of the bonding surface side plating layer. The opening has an insulating opening provided in the insulating layer, and a metal opening provided in the metal support layer,
The suspension according to any one of claims 1 to 6, wherein a length of the metal opening along the longitudinal direction of the connection terminal is longer than a length of the insulating opening along the longitudinal direction of the connection terminal. Substrate. Provided on the surface of the insulating layer on the wiring layer side, further comprising a protective layer covering the wiring;
The protective layer is provided with a protective opening that exposes the connection terminal,
The suspension substrate according to claim 7, wherein a length of the protective opening along the longitudinal direction of the connection terminal is longer than a length of the insulating opening along the longitudinal direction of the connection terminal. A base plate;
A suspension comprising the suspension substrate according to any one of claims 1 to 8, which is attached to the base plate via a load beam. The suspension according to claim 9,
A suspension with a head, comprising: the head slider mounted on the suspension. The suspension with a head according to claim 10,
The external connection board mounted on the tail region of the suspension board,
An assembly of a suspension with a head and an external connection board, wherein the external terminal of the external connection board is ultrasonically bonded to the joint surface of the connection terminal of the suspension board.   A hard disk drive comprising the combination of the suspension with a head according to claim 11 and the external connection board.

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