Abstract:
A method for manufacturing a magnetic head suspension assembly includes a step of forming a plurality of flexure pieces coupled with each other and kept substantially flat, each of the flexure pieces being provided with conductive connection pattern, a step of mounting head IC chips on the respective substantially flat flexure pieces, the mounting being executed before fixing of said flexure pieces to load beams, and a step of separating said flexure pieces with the head IC chips into individual pieces.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This is a continuation-in-part application of U.S. patent application Ser. No. 09/216,851 filed on Dec. 21, 1998. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a method for manufacturing a magnetic head suspension assembly with a head IC chip. The assembly includes a slider with at least one thin-film magnetic head element and a resilient suspension for supporting the slider. 
     DESCRIPTION OF THE RELATED ART 
     In such head suspension assembly, at least one thin-film magnetic head element for writing magnetic information into and/or reading magnetic information from a magnetic recording medium such as a magnetic disk is in general formed on a slider flying in operation above the magnetic recording medium. The slider is supported by the suspension made of a resilient thin metal plate. 
     A head IC chip used for amplifying writing current to the magnetic head element, for amplifying reading current from the head element and for controlling the writing and reading operations of the head element is also mounted on the suspension. Japanese patent unexamined publications nos. 53(1978)-69623, 55(1980)-150130 and 3(1991)-108120 disclose magnetic head suspension assemblies with the head IC chips mounted on the suspensions. 
     In fabricating these conventional magnetic head suspension assemblies, both the sliders and the head IC chips are mounted on the respective suspensions after bend portions called as “gram-loads” and side rail bend portions for reinforcement are formed at the suspensions. For example, Japanese patent unexamined publications nos. 54(1979)-94312 and 3(1991)-134875 disclose manufacturing processes of attaching sliders onto respective bent suspensions which are coupled to each other and of separating thereafter the coupled suspensions into the individual pieces. 
     As aforementioned, since the bent suspension according to the conventional art has a complicated three dimensional shape, fixing of the suspension itself to an assembling tool or a jig used for mounting the head IC chip becomes very difficult. Thus, precise alignment of the suspension with the head IC chip cannot be expected causing that assembling of the head IC chip with the suspension cannot be automated. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a method for manufacturing a magnetic head suspension assembly, whereby extremely accurate assembling of a head IC chip with a suspension can be expected. 
     Another object of the present invention is to provide a method for manufacturing a magnetic head suspension assembly, whereby assembling of a head IC chip with the suspension can be easily automated. 
     According to the present invention, a method for manufacturing a magnetic head suspension assembly includes a step of forming a plurality of flexure pieces coupled with each other and kept substantially flat, each of the flexure pieces being provided with conductive connection pattern, a step of mounting head IC chips on the respective substantially flat flexure pieces, the mounting being executed before fixing of said flexure pieces to load beams, and a step of separating said flexure pieces with the head IC chips into individual pieces. 
     In case of fabricating a magnetic head suspension assembly with a three-piece structure suspension formed from discrete components of a flexure piece and a load beam, the load beam is fixed to the flexure piece after the head IC chip is mounted on the flexure piece. 
     Since the head IC chips are mounted on the flexure pieces which are coupled with each other and kept substantially flat, the alignment and mounting of the head IC chips to the respective flexure pieces can be accurately and easily executed, and thus extremely accurate assembling of the head-suspension assemblies can be expected. This accurate assembling will greatly improve characteristics of the magnetic head suspension assembly. Furthermore, assembling of the head IC chips with the suspensions can be easily automated. Thus, the manufacturing costs of the fabricated magnetic head suspension assembly can be reduced without sacrificing quality. 
     It is preferred that the method further includes a step of checking electrical characteristics of the mounted head IC chips before fixing of the flexure pieces to the load beams. 
     It is also preferred that the method further includes a step of mounting sliders with magnetic head elements on the separated flexure pieces. 
     It is preferred that the head IC chip mounting step includes a step of mounting the head IC chips on the respective flexure pieces by flip chip bonding process or by ultrasonic bonding. 
     It is preferred that each of the flexure pieces has a tongue portion for fixing the slider, and that the method further includes a step of bending the tongue portions of the respective flexure pieces so as to adjust static attitude of the sliders to be attached. The tongue portion bending step may be executed before the head IC chips are mounted, after the head IC chips are mounted but before the coupled flexure pieces are separated into individual pieces, or after the coupled flexure pieces are separated into individual pieces. 
     It is also preferred that the method further includes a step of fixing a load beam to each of the separated flexure piece. This fixing step may be executed after the head IC chips are mounted but before the coupled flexure pieces are separated into individual pieces, or after the coupled flexure pieces are separated into individual pieces. 
     It is preferred that the forming step includes a step of forming the plurality of flexure pieces coupled with each other from a flat sheet material, or from a rolled hoop material. 
     It is also preferred that the mounting step includes a step of mounting sliders with magnetoresistive type read out magnetic head elements on the respective flexure pieces. 
     According to the present invention, a method for manufacturing a magnetic head suspension assembly includes a step of forming a plurality of flexure-load beam pieces coupled with each other and kept substantially flat, each of the flexure-load beam pieces being provided with conductive connection pattern, a step of mounting head IC chips on the respective substantially flat flexure-load beam pieces, the mounting being executed before the flexure-load beam pieces are bent, and a step of separating the flexure-load beam pieces with the head IC chips into individual pieces. 
     In case of fabricating a magnetic head suspension assembly with a two-pieces structure suspension formed from a flexure-load beam piece which serves both as a flexure and a load beam, bending process of the flexure-load beam piece is executed after the head IC chip is mounted on the flexure-load beam piece. 
     Since the head IC chips are mounted on the flexure-load beam pieces which are coupled with each other and kept substantially flat, the alignment and mounting of the head IC chips to the respective flexure-load beam pieces can be accurately and easily executed, and thus extremely accurate assembling of the head-suspension assemblies can be expected. This accurate assembling will greatly improve characteristics of the magnetic head suspension assembly. Furthermore, assembling of the head IC chips with the suspensions can be easily automated. Thus, the manufacturing costs of the fabricated magnetic head suspension assembly can be reduced without sacrificing quality. 
     It is preferred that the method further includes a step of checking electrical characteristics of the mounted head IC chips before the flexure-load beam pieces are bent. 
     It is also preferred that the method further includes a step of mounting sliders with magnetic head elements on the separated flexure-load beam pieces. 
     It is preferred that the head IC chip mounting step includes a step of mounting the head IC chips on the respective flexure-load beam pieces by flip chip bonding process or by ultrasonic bonding process. 
     It is preferred that each of the flexure-load beam pieces has a tongue portion for fixing the slider, and that the method further includes a step of bending the tongue portions of the respective flexure-load beam pieces so as to adjust static attitude of the sliders to be attached. The tongue portion bending step may be executed before the head IC chips are mounted, after the head IC chips are mounted but before the coupled flexure-load beam pieces are separated into individual pieces, or after the coupled flexure-load beam pieces are separated into individual pieces. 
     It is preferred that the method further includes a step of bending each of the flexure-load beam pieces. This flexure-load beam bending step may be executed after the head IC chips are mounted but before the coupled flexure-load beam pieces are separated into individual pieces, or after the coupled flexure-load beam pieces are separated into individual pieces. 
     It is also preferred that the forming step includes a step of forming the plurality of flexure-load beam pieces coupled with each other from a flat sheet material or from a rolled hoop material. 
     It is preferred that the mounting step includes a step of mounting sliders with magnetoresistive type read out magnetic head elements on the respective flexure-load beam pieces. 
     Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 a  and  1   b  show plane views illustrating parts of processes of a preferred embodiment of a method for manufacturing a magnetic head suspension assembly according to the present invention; 
     FIG. 2 shows an enlarged plane view of a flexure piece under the process of FIG. 1 a;    
     FIG. 3 shows a plane view of the magnetic head suspension assembly with a load beam and the flexure fixed to the load beam in the embodiment shown in FIGS. 1 a  and  1   b;    
     FIGS. 4 a  and  4   b  show plane views illustrating parts of processes of another embodiment of a method for manufacturing a magnetic head suspension assembly according to the present invention; 
     FIG. 5 shows an enlarged plane view of a flexure-load beam piece under the process of FIG. 4 a ; and 
     FIG. 6 shows a plane view of the flexure-load beam piece with the IC chip after the flexure-load beam bending in the embodiment shown in FIGS. 4 a  and  4   b.   
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 a  and  1   b  illustrate parts of fabricating processes of the preferred embodiment of the manufacturing method of the magnetic head suspension assembly according to the present invention. This embodiment relates to the magnetic head suspension assembly with a three-piece structure suspension formed from discrete components of a flexure, a load beam and a base plate. 
     First, on a flat thin metal plate or a flat metal sheet, a conductive layer with a thin-film conductive pattern that constitutes lead lines for each suspension is formed. This thin-film conductive pattern can be formed by a well-known method similar to the patterning method of forming printed circuits on a thin metal plate. Namely, the conductive pattern is formed by sequentially depositing a first insulation material layer made of a resin such as polyimide with a thickness of about 5 μm, a patterned Cu layer (conductive layer) with a thickness of about 4 μm, and a second insulation material layer made of a resin such as polyimide with a thickness of about 5 μm on the thin metal plate in this order. The thin metal plate is made of in this embodiment a stainless steel plate (for example SUS304TA) with a thickness of about 25 μm. 
     Then, as shown in FIG. 1 a , the thin metal plate with thus formed conductive layer is partially cut by for example an etching process to form a flexure blank  11  on which a plurality of flexure pieces  10  partially coupled with each other are arranged. Each of the flexure pieces  10  does not have bend portions at this stage, and therefore the flexure blank  11  is kept substantially flat. 
     FIG. 2 illustrates an enlarged one of the flexure pieces  10  at this state. In the figure, reference numeral  12  denotes the conductive layer with the thin-film conductive pattern that constitutes the lead lines running along the longitudinal direction of the flexure piece  10 . One end of the conductive layer  12  is connected to connection terminals  13  which will be connected to external circuits, and the other end of the conductive layer  12  is connected to connection terminals  14  which will be connected to terminals of a slider. On a middle portion of the conductive layer  12 , connection pads  15  for a head IC chip are formed. Within the regions of the connection terminals  13  and  14  and also the connection pads  15 , a Ni layer and an Au layer are sequentially deposited on the Cu layer and there is no second insulation material layer. 
     In FIG. 2, furthermore, reference numeral  16  denotes a tongue portion of the flexure piece  10  for carrying the slider. According to this embodiment, the tongue portion  16  is bent, at this stage namely before mounting the head IC chip, to adequately adjust static attitude of the slider that will be attached thereto. 
     Then, as shown in FIG. 1 b , head IC chips  17  are mounted on and connected to the connection pads  15  on the respective flexure pieces  10  of the flexure blank  11 . Each of the head IC chips  17  in this embodiment is formed by a bear chip and thus mounted on the pads  15  by flip chip bonding using solder. In modifications, the head IC chip  17  may be mounted on the pads  15  by ultrasonic bonding using Au bumps. In the latter case, since no soldering flux is used, contamination at the bonding portion will never occur. Thus, no cleaning process after the head IC chip mounting process is necessary resulting the manufacturing processes of the head suspension assembly to simplify. 
     After mounting the head IC chips  17  on the flexure pieces  10 , the performance of the head IC chips  17  and electrical connection between the head IC chips  17  and the pads  15  are checked by an electrical characteristics testing process. This testing process will be executed by connecting a dummy resistor which corresponds to a read out element of the magnetic head and a dummy inductor which corresponds to a write element of the magnetic head to the connection terminal  14  of each flexure piece  10 , by inputting a signal which will be applied to the head IC chip into the connection terminal  13  and by measuring the output signal from the head IC chip  17 . 
     Thereafter, the coupled flexure pieces  10  on which the head IC chips  17  are mounted are separated into individual pieces. Then, as shown in FIG. 3, a load beam  19  at which a bend portion of “gram-load”  20  and side rail bend portions for reinforcement  21  and  22  are preliminarily formed is fixed on the bottom surface of the flexure piece  10 . The flexure piece  10  and the load beam  19  constitute the fundamental portion of the suspension. In FIG. 3, reference numeral  23  denotes a base plate attached to the end portion of the load beam  19 . 
     The load beam  19  is made of in this embodiment a stainless steel plate with a thickness of about 70-75 μm and supports the flexure piece  10  along its whole length. This load beam  19  has a shape with a width that narrows with approaching to its top end. Fixing of the flexure piece  10  with the load beam  19  is achieved by means of a plurality of welded spots. 
     After that, as shown in FIG. 3, a slider  18  with a magnetic head element such as a MR read out element is mounted on the tongue portion  16  of the flexure piece and electrodes (not shown) of the slider  18  are electrically connected to the connection terminals  14 . 
     When mounting the head IC chips  17  on the flexure pieces  10 , it is necessary to accurately align connection electrodes (not shown) of each head IC chip to the connection pads  15 . However, as mentioned above, according to this embodiment, the head IC chips  17  are mounted on the substantially flat flexure blank  11 . Therefore, the alignment and mounting of the head IC chips to the respective flexure pieces can be accurately and easily executed, and thus extremely accurate assembling of the head-suspension assemblies can be expected. Furthermore, assembling of the head IC chips with the suspensions can be easily automated. Thus, the manufacturing costs of the fabricated magnetic head suspension assembly can be reduced without sacrificing quality. 
     Furthermore, since the electrical characteristics test of the head IC chips  17  is executed with the substantially flat flexure blank  11 , electrical contacts of probes with the connection terminals  13  and  14  can become easy. Also, the testing process of the head IC chips  17  mounted on each flexure piece of the flexure blank  11  can be easily automated. In addition, since the electrical characteristic test is executed at this early stage, remounting of another head IC chip becomes easy when it is found that the mounted head IC chip is defective. Alternately, no following process will be executed for the flexure piece to avoid needless processes when it is found that the head IC chip mounted on this flexure piece is defective. 
     In a modification of the present invention, the bending work of the tongue portions  16  of the respective flexure pieces to adjust static attitude of the sliders to be attached may be executed after the head IC chips are mounted but before the flexure pieces are separated. In a further modification of the present invention, the bending work of the tongue portions  16  of the respective flexure pieces may be executed after the flexure pieces are separated. 
     Although the flexure blank  11  is made from a flat thin metal plate in the aforementioned embodiments, such the flexure blank can be made in another embodiment by roll to roll process using a rolled hoop material as TAB (Tape Automated Bonding) process. 
     In another modification, fixing of the flexure piece  10  with the load beam  19  may be executed after the head IC chips  17  are mounted but before the coupled flexure pieces  10  are separated into individual pieces. 
     FIGS. 4 a  and  4   b  illustrate parts of fabricating processes of another embodiment of the manufacturing method of the magnetic head suspension assembly according to the present invention. This embodiment relates to the magnetic head suspension assembly with a two-piece structure suspension in which the flexure and the load beam are integrated from the beginning. 
     First, on a flat thin metal plate or a flat metal sheet, a conductive layer with a thin-film conductive pattern that constitutes lead lines for each suspension is formed. This thin-film conductive pattern can be formed by a well-known method similar to the patterning method of forming printed circuits on a thin metal plate. Namely, the conductive pattern is formed by sequentially depositing a first insulation material layer made of a resin such as polyimide with a thickness of about 5 μm, a patterned Cu layer (conductive layer) with a thickness of about 4 μm, and a second insulation material layer made of a resin such as polyimide with a thickness of about 5 μm on the thin metal plate in this order. The thin metal plate is made of in this embodiment a stainless steel plate (for example SUS304TA) with a thickness of about 70-75 μm. 
     Then, as shown in FIG. 4 a , the thin metal plate with thus formed conductive layer is partially cut by for example an etching process to form a flexure-load beam blank  41  on which a plurality of flexure-load beam pieces  40  partially coupled with each other are arranged. Each of the flexure-load beam pieces  40  does not have bend portions at this stage, and therefore the flexure-load beam blank  41  is kept substantially flat. 
     FIG. 5 illustrates an enlarged one of the flexure-load beam pieces  40  at this state. In the figure, reference numeral  42  denotes the conductive layer with the thin-film conductive pattern that constitutes the lead lines running along the longitudinal direction of the flexure-load beam piece  40 . One end of the conductive layer  42  is connected to connection terminals  43  which will be connected to external circuits, and the other end of the conductive layer  42  is connected to connection terminals  44  which will be connected to terminals of a slider. On a middle portion of the conductive layer  42 , connection pads  45  for a head IC chip are formed. Within the regions of the connection terminals  43  and  44  and also the connection pads  45 , a Ni layer and an Au layer are sequentially deposited on the Cu layer and there is no second insulation material layer. 
     In FIG. 5, furthermore, reference numeral  46  denotes a tongue portion of the flexure-load beam piece  40  for carrying the slider. According to this embodiment, the tongue portion  46  is bent, at this stage namely before mounting the head IC chip and the slider, to adequately adjust static attitude of the slider that will be attached thereto. 
     Then, as shown in FIG. 4 b , head IC chips  47  are mounted on and connected to the connection pads  45  on the respective flexure-load beam pieces  40  of the flexure-load beam blank  41 . Each of the head IC chips  47  in this embodiment is formed by a bear chip and thus mounted on the pads  45  by flip chip bonding using solder. In modifications, the head IC chip  47  may be mounted on the pads  45  by ultra sonic bonding using Au bumps. In the latter case, since no soldering flux is used, contamination at the bonding portion will never occur. Thus, no cleaning process after the head IC chip mounting process is necessary resulting the manufacturing processes of the head suspension assembly to simplify. 
     After mounting the head IC chips  47  on the flexure-load beam pieces  40 , the performance of the head IC chips  47  and electrical connection between the head IC chips  47  and the pads  45  are checked by an electrical characteristics testing process. This testing process will be executed by connecting a dummy resistor which corresponds to a read out element of the magnetic head and a dummy inductor which corresponds to a write element of the magnetic head to the connection terminal  44  of each flexure-load beam piece  40 , by inputting a signal which will be applied to the head IC chip into the connection terminal  43  and by measuring the output signal from the head IC chip  47 . 
     Thereafter, the coupled flexure-load beam pieces  40  on which the head IC chips  47  are mounted are separated into individual pieces. Then, as shown in FIG. 5, bending works of the flexure-load beam pieces, namely forming of bend portion of “gram-load”  50  and side rail bend portions for reinforcement  51  and  52  is executed. This bending works may be executed before separation of the coupled flexure-load beam pieces  40  but after the head IC chips  47  are mounted. 
     After that, although it is not shown in the figures, a slider with a magnetic head element such as a MR read out element is mounted on the tongue portion  46  of the flexure-load beam piece and electrodes (not shown) of the slider are electrically connected to the connection terminals  44 . 
     When mounting the head IC chips  47  on the flexure-load beam pieces  40 , it is necessary to accurately align connection electrodes (not shown) of each head IC chip to the connection pads  45 . However, as mentioned above, according to this embodiment, the head IC chips  47  are mounted on the substantially flat flexure-load beam blank  41 . Therefore, the alignment and mounting of the head IC chips to the respective flexure-load beam pieces can be accurately and easily executed, and thus extremely accurate assembling of the head-suspension assemblies can be expected. Furthermore, assembling of the head IC chips with the suspensions can be easily automated. Thus, the manufacturing costs of the fabricated magnetic head suspension assembly can be reduced without sacrificing quality. 
     Furthermore, since the electrical characteristics test of the head IC chips  47  is executed with the substantially flat flexure-load beam blank  41 , electrical contacts of probes with the connection terminals  43  and  44  can become easy. Also, the testing process of the head IC chips  47  mounted on each flexure piece of the flexure-load beam blank  41  can be easily automated. In addition, since the electrical characteristic test is executed at this early stage, remounting of another head IC chip becomes easy when it is found that the mounted head IC chip is defective. Alternately, no following process will be executed for the flexure-load beam piece to avoid needless processes when it is found that the head IC chip mounted on this flexure-load beam piece is defective. 
     In a modification, the bending work of the tongue portions  46  of the respective flexure-load beam pieces to adjust static attitude of the sliders to be attached may be executed after the head IC chips are mounted but before the flexure-load beam pieces are separated. In a further modification of the present invention, the bending work of the tongue portions  46  of the respective flexure-load beam pieces may be executed after the flexure-load beam pieces are separated. 
     Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.