Patent Publication Number: US-6341415-B2

Title: Method for assembling a magnetic head assembly and magnetic disk drive using bonding balls connecting magnetic head terminals to wiring terminals

Description:
CROSS REFERENCE TO THE RELATED PRIORITY APPLICATIONS 
     This application is a Continuation-In-Part application of both U.S. application Ser. No. 08/774,554 filed Dec. 30, 1996 and U.S. application Ser. No. 08/896,435 filed Jul. 18, 1997 now U.S. Pat. No. 6,002,550. U.S. application Ser. No. 08/896,435 is a divisional application of U.S. application Ser. No. 08/030,365 filed Mar. 17, 1993, which is now abandoned in favor of an FWC application Ser. No. 08/896,729 filed Jul. 18, 1997 now U.S. Pat. No. 6,141,182. Application 08/774,554 is itself a Continuation-In-Part of both U.S. application Ser. No. 08/613,601 filed Mar. 11, 1996 and U.S. application Ser. No. 08/248,334 filed May 24, 1994 now U.S. Pat. No. 5,612,840. U.S. application Ser. No. 08/613,601 is an FWC of U.S. application Ser. No. 08/110,771 filed Aug. 23, 1993, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a magnetic head assembly having a thin-film or MR type magnetic head used for a magnetic disk drive. 
     2. Description of the Related Art 
     Recently, in conventional magnetic disk drives, monolithic type magnetic heads have been replaced with thin-film or MR type magnetic heads. 
     FIG. 1A is an exploded view of an example of a magnetic head assembly (which can also be referred to as a magnetic head suspension unit) having a thin-film type magnetic head used for the conventional magnetic disk drives. FIG. 1B is an exploded view of a part of the magnetic head suspension unit shown in FIG.  1 A. In the present specification, the magnetic head suspension unit refers to an assembly of a spring arm having a magnetic head mounted on an end of the spring arm. The other end of the spring arm is adapted to be mounted on a member of a magnetic head positioning mechanism. 
     Referring now to FIG. 1A, one end (a base portion  1   a ) of a spring arm (suspension)  1  formed of an elastic plate is mounted to a member of a magnetic head positioning mechanism (not shown in the figure) via a plate-like spacer  2 . A gimbal  3  is mounted on another end  1   b  of the spring arm  1 . The gimbal  3  is mounted, as shown in FIG. 1B, on the spring arm  1  by means of laser welding at positions indicated by x. A core slider (head slider)  4  of a magnetic head h is mounted by adhesive on the gimbal  3 . 
     Two magnetic head elements  5  are formed on a rear side surface of the magnetic head, the magnetic head elements  5  being connected by lead wires  6  which lead to a read wire  8  covered with an insulating tube  7  fixed to the spring arm  1 . The lead wire  8  is lead to a recording/reproducing circuit  9  shown in FIG.  2 . 
     The spring arm  1  is slightly bent near the base portion  1   a  so that a bent portion  1   c  is formed so as to generate a spring force. 
     FIG. 2 is an exploded view of a conventional magnetic disk drive in which two magnetic head suspension units shown in FIG. 1A are used. 
     Two magnetic head suspension units are mounted on a driving arm  13  which pivots about an axis  12  so that a magnetic disk  10  accommodated inside the magnetic head drive is sandwiched between two of the core sliders  4  mounted on the respective spring arms  1 . Each of the core sliders  4  is pressed to a respective surface of the magnetic disk  10  by the spring force generated by the bent portion  1   c.    
     When the magnetic disk  10  is rotated at a high speed, the magnetic heads h float, if the magnetic heads h are of the floating type, on the respective surface of the magnetic disk  10  due to an air flow generated by the rotation of the magnetic disk  10 . If the magnetic heads h are contact type magnetic heads, the magnetic heads h do not float, but instead slide on the respective surfaces of the magnetic disk  10 . The magnetic heads h are moved to respective target tracks on the surfaces of the magnetic disk  10  by pivoting the spring arms about the axis  12 . 
     FIG. 3 is a perspective view of a thin-film type magnetic head. FIG. 4 is an enlarged cross sectional view of the thin-film type magnetic head shown in FIG. 3 taken along a line A—A of FIG.  3 . 
     The thin-film type magnetic head shown in FIG. 3 comprises the slider  4  and head elements  5 . The head elements  5  are formed by means of a film deposition technique and lithography. Terminals  15   a  and  15   b  for recording/reproducing coils are provided near the head elements  5 . 
     Each of the head elements  5  comprises a lower magnetic pole  16 , an upper magnetic pole  17  and a thin-film coil  19  wound around a connecting portion  18  between the lower magnetic pole  16  and the upper magnetic pole  17 . A gap insulating layer  20  is provided between the lower magnetic pole  16  and the upper magnetic pole  17  so that a gap G having a predetermined width is formed between the two poles. The gap G faces the surface of the magnetic disk  10  to perform an magnetic recording/reproducing operation. 
     In the construction of the magnetic head suspension unit shown in FIG. 1 in which the lead wire  8  is covered with the insulating tube  7 , the insulating tube  7  occupies a relatively large space to prevent miniaturization of the magnetic disk drive. Additionally, the insulating tube  7  makes an assembling operation difficult, particularly an automated assembling operation. Further, there is a strong possibility that the lead wire  8  will pick up noises, resulting in degradation of an S/N ratio of a signal sent via the lead wire  8 . 
     In order to eliminate the above-mentioned problems, a method for forming a signal transmitting line on a spring arm is suggested in Japanese Laid-Open Patent Application No.4-21918. In the method, a signal line is formed of a pattern of a conductive layer on an insulating layer formed on the spring arm. However, the method has a problem in that the signal transmitting line formed of the conductive layer is easily damaged or broken during a process for forming the bent portion  1   c  shown in FIG.  1 A. 
     Japanese Laid-Open Patent Application No.4-111217 discloses a magnetic head suspension unit in which a flexible printed circuit board is attached to a spring arm, and a portion of the flexible circuit board corresponding to the above of the spring arm bent portion is not adhered to the spring arm. Instead, in this construction, the portion of the flexible printed circuit board corresponding to the bent portion of the spring arm is free, and thus there is no bending stress applied to the flexible printed circuit board. However, this construction cannot be applied to a highly miniaturized spring arm such as a spring arm having a thickness of a few microns and a 4.6 mm width. 
     There is another problem in that ability of the insulating layers  21  and  22  of the magnetic head element  5  to withstand dielectric voltage is very low because they each have a thickness of only 1 to a few microns. Accordingly, if a relatively high voltage of about 100V or more is applied between the thin-film coil  19  and the poles  16  and  17  due to a generation of static electricity, the insulating layers  21  and  22  may be easily damaged due to electric discharge. 
     If the insulation between the thin-film coil  19  and the poles  16  or  17  is damaged, an electric discharge may occur between the core slider, which is made of a conductive material such as Al 2 O 3 TiC, and the magnetic poles  16  or  17 , resulting in the gap G or the floating surface of the core slider  4  being damaged. Additionally, when the magnetic disk drive is in operation, an electric discharge may occur between the magnetic disk  10  and the magnetic poles  16  or  17 , resulting in the magnetic gap G being damaged. When the core slider  4  is damaged, the floating characteristic of the magnetic head is deteriorated, which condition causes a generation of noises in the recording/reproducing signal. If the magnetic head is a contact type head, the damaged surface of the magnetic head may scratch the magnetic disk  10 . 
     Problems similar to the above-mentioned problems may occur when the core slider is miniaturized. That is, when the magnetic head is heated, the magnetic head tends to expand due to the thermal expansion, but a portion of the core slider attached to the gimbal or the spring arm by adhesive cannot expand in accordance with the expansion of the magnetic head. This creates bending of the core slider, and thus the floating characteristic of the magnetic head may be deteriorated. 
     SUMMARY OF THE INVENTION 
     It is a general object of the present invention to provide an improved and useful magnetic head assembly and a magnetic disk drive having such a magnetic head suspension unit in which the above-mentioned disadvantages are eliminated. 
     A more specific object of the present invention is to provide a magnetic head assembly and a magnetic disk drive in which damaging of a conductive-pattern layer formed on a spring arm during a process of bending the spring arm can be prevented. 
     Another object of the present invention is to provide a magnetic head assembly and a magnetic disk drive in which no insulation breakage occurs due to generation of static electricity. 
     Another object of the present invention is to provide a magnetic head assembly and a magnetic disk drive in which thermal deformation of a slider core is prevented. 
     In order to achieve the above-mentioned objects, there is provided according to the present invention, a magnetic head assembly comprising: 
     a slider on which a magnetic head is mounted, the slider having terminals of the magnetic head; 
     a gimbal portion on which the slider is mounted; 
     terminals of wiring lines; and 
     balls bonding the terminals of the wiring lines and the terminals of the slider. 
     The magnetic head assembly may be configured so that the balls are made of gold. 
     The magnetic head assembly may be configured so that the terminals of the wiring lines are provided on the gimbal portion. 
     The magnetic head assembly may be configured so that the wiring lines are formed by a wiring pattern. 
     The magnetic head assembly may be configured so that the slider is provided on a surface of the gimbal portion on which the wiring lines are provided. 
     The magnetic head assembly may be configured so that the slider is provided on the gimbal portion so that the terminals of the wiring pattern and the terminals of the slider face each other in an orthogonal formation. 
     The magnetic head assembly may be configured so that the gimbal portion is a part of a suspension so that the gimbal portion is integrally formed with the suspension. 
     The magnetic head assembly may be configured so that the wiring lines are formed by a wiring pattern formed on the suspension. 
     The magnetic head assembly may be configured so that the slider is provided on a surface of the gimbal portion on which the wiring lines are provided. 
     The magnetic head assembly may be configured so that the slider is provided on the gimbal portion so that the terminals of the wiring pattern and the terminals of the slider face each other in an orthogonal formation. 
     The above objects of the present invention are also achieved by a magnetic disk drive comprising: 
     an enclosure; 
     a magnetic disk provided in the enclosure; 
     a magnetic head assembly provided in the enclosure; and 
     an actuator to which the magnetic head suspension unit is fixed, the actuator moving the magnetic head assembly above the magnetic disk, wherein the magnetic head assembly is configured as described above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The other objects, features and advantages of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: 
     FIG. 1A is an exploded view of an example of a magnetic head assembly having the thin-film type magnetic head used for the conventional magnetic disk drives; 
     FIG. 1B is an exploded view of a part of the magnetic head assembly shown in FIG. 1A; 
     FIG. 2 is an exploded view of a conventional magnetic disk drive in which two magnetic head assemblies shown in FIG. 1A are used; 
     FIG. 3 is a perspective view of a thin-film type magnetic head; 
     FIG. 4 is an enlarged cross sectional view of the thin-film type magnetic head shown in FIG. 3 taken along a line  4 — 4  of FIG. 3; 
     FIG. 5A is a perspective view of a first embodiment of a magnetic head assembly according to the present invention; 
     FIG. 5B is an enlarged cross sectional view taken along a line b—b of FIG. 5A; 
     FIG. 6A is a perspective view of the spring arm shown in FIG. 5A in a state where a magnetic head has not been mounted on a gimbal; 
     FIG. 6B is an illustration showing a process for forming conductive-pattern layers on the spring arm; 
     FIGS. 7A through 7C are illustrations showing a process for bending the bent portions shown in FIG. 6A; 
     FIG. 8A is a perspective view of a second embodiment of a magnetic head assembly according to the present invention; 
     FIG. 8B is an enlarged partial cross sectional view taken along a line b—b of FIG. 8A; 
     FIG. 8C is an enlarged partial cross sectional view taken along a line c—c of FIG. 8A; 
     FIG. 8D is a partial cross sectional view of a variation of the spring arm shown in FIG. 8A; 
     FIG. 9A is a perspective view of a third embodiment of a magnetic head assembly according to the present invention; 
     FIG. 9B is a cross sectional view taken along a line B—B of FIG. 9A; 
     FIG. 10 is a perspective view of a fourth embodiment of a magnetic head assembly according to the present invention; 
     FIG. 11A is a perspective view of a fifth embodiment of a magnetic head assembly according to the present invention; 
     FIG. 11B is an enlarged partial cross sectional view taken along a line B—B of FIG.  11 A. 
     FIG. 12A is a perspective view of a sixth embodiment of a magnetic head assembly according to the preset invention; 
     FIG. 12B is an enlarged partial cross sectional view taken along a line b—b of FIG. 12A; 
     FIG. 12C is an enlarged partial cross sectional view taken along a line C—C of FIG. 12A; 
     FIG. 13A is a perspective view of a seventh embodiment of a magnetic head assembly according to the present invention; 
     FIG. 13B is a variation of the embodiment shown in FIG. 13A; 
     FIG. 14 is a perspective view of an eighth embodiment of a magnetic head assembly according to the present invention; 
     FIG. 15A is a perspective view of the magnetic head shown in FIG. 14; 
     FIG. 15B is a cross sectional view taken along a line B—B of FIG. 15A; 
     FIG. 16 is an exploded view of an essential part of a ninth embodiment of a magnetic head assembly according to the present invention; 
     FIG. 17 is an exploded view of an essential part of a variation of the ninth embodiment shown in FIG. 16; 
     FIG. 18 is a perspective view of an essential part of a tenth embodiment of a magnetic head assembly according to the present invention; 
     FIG. 19 is an exploded view of an eleventh embodiment of a magnetic head assembly according to the present invention; 
     FIG. 20A is a perspective view of a spring arm of a twelfth embodiment of a magnetic head assembly according to the present invention; 
     FIG. 20B is an enlarged cross sectional view of a mounting structure of the core slider shown in FIG. 20A; 
     FIGS. 21A through 21F are illustrations of variations of the hole shown in FIG. 20A; and 
     FIG. 22A is a perspective view of a spring arm of a thirteenth embodiment of a magnetic head assembly according to the present invention; 
     FIG. 22B is an enlarged cross sectional view of a mounting structure of the core slider shown in FIG. 22A; 
     FIG. 22C is an enlarged cross sectional view showing a variation of the mounting structure shown in FIG. 22B; 
     FIG. 23 is a perspective view of a magnetic head assembly according to a fourteenth embodiment of the present invention; 
     FIG. 24 is a plan view of a 3.5-inch magnetic disk drive to which the magnetic head assembly shown in FIG. 23 is applied; 
     FIG. 25 is a perspective view of a first-order bend state of a suspension shown in FIG. 23; 
     FIG. 26 is a perspective view of a first-order twist state of the suspension shown in FIG. 23; 
     FIG. 27 is a perspective view of the upper side of the magnetic head assembly shown in FIG. 23; 
     FIG. 28 is a side view of the magnetic head assembly shown in FIG. 23; 
     FIG. 29 is a perspective view of a magnetic head assembly according to a fifteenth embodiment of the present invention; 
     FIG. 30 is a perspective view of a magnetic head assembly according to a sixteenth embodiment of the present invention; 
     FIG. 31 is a perspective view of a magnetic head assembly according to the twelfth embodiment of the present invention; 
     FIG. 32 is a side view of the mechanism shown in FIG. 31; 
     FIG. 33 is a perspective view of a magnetic head assembly according to an eighteenth embodiment of the present invention; 
     FIG. 34 is a perspective view of a magnetic head assembly according to a nineteenth embodiment of the present invention; 
     FIG. 35 is a plan view of a free-end part of a suspension shown in FIG. 34; 
     FIG. 36 is a sectional-view taken along a line XIV—XIV shown in FIG. 34; 
     FIG. 37 is a perspective view of a magnetic head slider shown in FIG. 34; 
     FIG. 38 is a flowchart of a production process for the suspension shown in FIG. 34; 
     FIG. 39 is a plan view of a plate obtained after an etching step shown in FIG. 38 is carried out; 
     FIG. 40 is a flowchart of another production process for the suspension shown in FIG. 34; 
     FIG. 41 is a perspective view of a variation of the nineteenth embodiment of the present invention; 
     FIG. 42 is a perspective view of a magnetic head assembly according to a twelfth embodiment of the present invention; 
     FIG. 43 is a plan view of a magnetic disk drive to which the magnetic head assembly shown in FIG. 42 is applied; 
     FIGS. 44A and 44B are respectively plan and side views of the magnetic head assembly shown in FIG. 42; 
     FIG. 45 is a side view of a state observed when the magnetic head assembly shown in FIG. 42 is provided in the magnetic disk drive; 
     FIG. 46 is an emphasized view of the state in FIG. 45; 
     FIG. 47 is a side view of a first-order bend state of a suspension used in the twelfth embodiment of the present invention; 
     FIG. 48 is a side view of a first-order twist state of the suspension used in the twelfth embodiment of the present invention; 
     FIG. 49 is a plan view of a first variation of a gimbal of the suspension used in the twelfth embodiment of the present invention; 
     FIG. 50 is a plan view of a second variation of the gimbal of the suspension used in the twelfth embodiment of the present invention; 
     FIG. 51 is a plan view of a third variation of the gimbal of the suspension used in the twelfth embodiment of the present invention; 
     FIG. 52 is a plan view of a fourth variation of the gimbal of the suspension used in the twelfth embodiment of the present invention; 
     FIG. 53 is a plan view of a fifth variation of the gimbal of the suspension used in the twelfth embodiment of the present invention; and 
     FIG. 54 is a side view of a variation of the twelfth embodiment of the present invention. 
     FIG. 55 is a top view of another embodiment of a magnetic disk apparatus of the present invention; 
     FIG. 56 is a cross section of the magnetic disk apparatus in FIG. 55; 
     FIG. 57 is a top view of an actuator in FIG. 55; 
     FIG. 58 is a perspective view of a magnetic head assembly according to a further embodiment of the present invention; 
     FIG. 59 illustrates another connecting mechanism of the magnetic head assembly in FIG. 58; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will now be given, with reference to FIGS. 5A and 5B, of a first embodiment of the present invention. FIG. 5A is a perspective view of a first embodiment of a magnetic head assembly according to the present invention, and FIG. 5B is an enlarged cross sectional view taken along a line B—B of FIG.  5 A. Hereinafter, the magnetic head assembly is also referred to a magnetic head suspension unit or merely suspension unit. In FIGS. 5A and 5B, parts that are the same as the parts shown in FIG. 1A are given the same reference numerals, and descriptions thereof will be omitted. 
     The first embodiment according to the present invention comprises the spring arm  1  and the core slider  4  of the magnetic head. A gimbal  24  supported by bridge portions  23   a  and  23   b  is formed on the end  1   b  of the spring arm  1 . The core slider (head slider)  4  of the magnetic head is mounted on the gimbal  24  by an adhesive which has an insulation effect and can be an insulation adhesive or an adhesive containing an insulator. The insulation adhesive is an insulator in which the insulator itself has the insulation effect. 
     The base portion (attachment portion)  1   a  of the spring arm  1  is fixed to a member of a magnetic head positioning mechanism. Conductive-pattern layers  25  run from the base portion l a  to the gimbal  24  so as to transmit signals to/from the magnetic head. 
     FIG. 6A is a perspective view of the spring arm  1  shown in FIG. 5A in a state where the magnetic head has not been mounted on the gimbal  24 . In FIG. 6A, a portion of the core slider  4  is also shown to explain electrical connection between the magnetic head and the conductive-pattern layers  25 . A pad  25   a  is formed at the end of each of the two conductive-pattern layers  25 . The core slider of the magnetic head is also provided with pads  26 . When the core slider  4  is mounted on the gimbal  24 , the pads  26  make contact with the respective pads  25   a.  The pads  26  and the pads  25   a  are then soldered together to assure an electric connection. It should be noted that the core slider  4  in FIG. 6A is viewed from a direction indicated by an arrow B of FIG.  5 A. 
     The conductive-pattern layers  25  on the spring arm  1  are formed by a process shown in FIG.  6 B. As shown by FIG. 6B-2, an insulating layer  27  is formed on the spring arm  1  by applying a polyimide resin over the spring arm  1  made of stainless steel. The thickness of the spring arm  1  is about 25 μm, and the thickness of the insulating layer  27  is 3-4 μm. A base layer  28  is then formed on the insulating layer  27 , as shown in FIG. 6B-3, by sputtering copper (Cu) onto the insulating layer  27 . The base layer  28  may instead be formed by vapor deposition or chemical plating. 
     Using the base layer  28 , electro plating is performed to form a copper layer  29  on the base layer  28 , as shown in FIG. 6B-4. As shown in FIG. 6B-5, the base layer  28  and the copper layer  29  are etched so that the conductive-pattern layers  25  remain on the spring arm  1 . Lastly, polyimide resin is applied over the conductive-pattern layers  25  so as to form an insulating film  30  which covers the conductive-pattern layers  25  to protect them. 
     If a bending process is performed by applying a pressing force to the conductive-pattern layers  25  formed on the spring arm  1 , the conductive-pattern layers  25  may be damaged or destroyed. In order to eliminate this problem, in the first embodiment of the present invention, rectangular holes  31   a  and  31   b  are formed on the spring arm  1 , as shown in FIG. 5A, on either side of the conductive-pattern layers  25 . The rectangular holes  31   a  and  31   b  separate a portion of the spring arm  1 , on which the conductive-pattern layers  25  are formed, from bent portions  33   a  and  33   b  to which a pressing force is applied to bend the spring arm  1 . The rectangular holes  31   a  and  31   b  may instead be slits  32   a  and  32   b  as shown in FIG.  6 A. 
     FIGS. 7A through 7C are illustrations showing a process for bending the bent portions  33   a  and  33   b.  As shown in FIG. 7A, first a roller  34  having larger diameter portions  35   a  and  35   b  is prepared. The larger diameter portions  35   a  and  35   b  bends the corresponding bent portions  33   a  and  33   b.  The bent portions  33   a  and  33   b,  which are formed as an elastic portion R generating an elastic force, of spring arm  1  are placed on a rubber table  36 . The roller  34  is then rolled, as shown in FIG. 7B, on the bent portion  33   a  and  33   b  while it is being pressed. As a result, only the bent portions  33   a  and  33   b  are permanently deformed into an arc-like shape, while the portion of the spring arm  1 , on which portion the conductive-pattern layers are formed, between the bent portions  33   a  and  33   b  is elastically deformed. 
     According to the present embodiment, the roller  34  is not pressed on the portion where the conductive-pattern layers  25  have been formed, and thus no damage to the conductive-pattern layers  25  occurs. 
     A description will now be given, with reference to FIGS. 8A through 8D, of a second embodiment according to the present invention. FIG. 8A is a perspective view of a second embodiment of a magnetic head suspension unit according to the present invention; FIG. 8B is an enlarged partial cross sectional view taken along a line b—b of FIG. 8A; FIG. 8C is an enlarged partial cross sectional view taken along a line c—c of FIG.  8 A. FIG. 8D is a partial cross sectional view of a variation of the spring arm shown in FIG.  8 A. 
     In the present embodiment, a recessed portion  39  is formed in the elastic portion R where an elastic force is generated. The conductive-pattern layers  25  are formed in the recessed portion  39 . The recessed portion  39  covers an entire length C of the elastic portion R and a width B so as to cover the portions of the conductive-pattern layers  25  located in the elastic portion R of the spring arm  1 . 
     In this embodiment, a portion of the insulating layer  27  shown in FIG. 6B-2 is formed also inside the recessed portion  39 . The base layer  28  and the copper layer  29  are then formed on the entire surface of the insulating layer  27  including the portion thereof inside the recessed portion  39  so as to form the conductive-pattern layers  25 . Lastly, the insulating layer  30  is formed on the conductive-pattern layers  25  so that a top surface of the insulating layer  30  located inside the recessed portion  39  is below the surface of the spring arm  1  as shown in FIG.  8 B. 
     In the present invention, since the portion inside the recessed portion  39  do not come into contact with the roller for forming the bent portions even though the roller has a straight cylindrical surface, no damage occurs to the conductive-pattern layers  25 , the same as in the case of the above-mentioned first embodiment. 
     Although in the above embodiment the recessed portion  39  is formed by means of etching, the recessed portion  39  may instead be formed by means of press forming as shown in FIG.  8 D. By using press forming, the recessed portion  39  can be formed even if the thickness of the spring arm  1  is very slight or the total thickness of the insulating layers  27  and  30  and the conductive-pattern layers  25  is great. The recessed portion  39  may be formed so that an entire length  25 L of straight portions of the conductive-pattern layers  25  is embedded in the recessed portion  39 . 
     A description will now be given, with reference to FIGS. 9A and 9B, of a third embodiment according to the present invention. FIG. 9A is a perspective view of a third embodiment of a magnetic head suspension unit according to the present invention; FIG. 9B is a cross sectional view taken along a line b—b of FIG.  9 A. 
     In the present embodiment, portions  25   r  of the conductive-pattern layers  25 , corresponding to the elastic portion R which generates an elastic force, are wider than other portions of the conductive-pattern layers  25 . That is, a width C 1  of each of the portion  25   r  of the conductive-pattern layers  25  within the elastic portion R is widened over a length L corresponding to the elastic portion R. The total thickness of the conductive-pattern layers  25  and insulating layers  27  and  30  is uniform over the entire width of the widened portions  25   r  of the conductive-pattern layers  25 . A roller  35  having a straight cylindrical surface is pressed over the entire width of the elastic portion R so as to bend the elastic portion R. 
     If the conductive-pattern layers  25  or the insulating layer  30  in the elastic portion R are protruded as shown in FIG. 6B, the pressing force exerted by the roller  35  is concentrated onto the conductive-pattern layers  25 . However, in the present embodiment, the pressing force is dispersed onto the entire width of the widened conductive-pattern layers  25 , and thus damage or breakage of the conductive-pattern layers  25  is prevented. Additionally, even if damage such as a cracking of portions of the conductive-pattern layers  25  occurs, other portions of the layers  25  which are not damaged, resulting in reliable electric continuity. In the present embodiment, the width c 1  of each of the portion  25   r  of the conductive-pattern layers  25  is 2.0 mm, and the length L is 1.5 mm. 
     A description will now be given, with reference to FIG. 10, of a fourth embodiment according to the present invention. FIG. 10 is a perspective view of a fourth embodiment of a magnetic head suspension unit according to the present invention. 
     In the present embodiment, zigzagging conductive-pattern portions  25   z  of the conductive-pattern layers  25  within the elastic portion R are formed to extend in a direction oblique to a direction in which other portions of the conductive-pattern layers  25  extend. Preferably, U-turn portions  25   c  are formed with a width greater than other portions. As a result, in the present embodiment, pressing force is dispersed over the contacting area of the roller to be pressed, thus reducing damaging and breakage of the conductive-pattern layers  25 . 
     A description will now be given, with reference to FIGS. 11A and 11B, of a fifth embodiment of the present invention. FIG. 11A is a perspective view of a fourth embodiment of a magnetic head suspension unit according to the present invention; FIG. 11B is an enlarged partial cross sectional view taken along a line b—b of FIG.  11 A. 
     In the present embodiment, a plurality of dummy patterns  25   d  are formed within the elastic portion R. The dummy patterns  25   d  have the same construction as the conductive-pattern layers  25 . When the elastic portion R is pressed by the roller  35  as shown in FIG. 11B, the pressing force is dispersed onto the dummy patterns  25   d,  and thus damage and breakage of the conductive-pattern layers  25  is prevented unlike in the case of the conventional conductive-pattern layers in which the pressing force is concentrated onto the conductive-pattern layers. 
     FIG. 12A is a perspective view of a sixth embodiment of a magnetic head suspension unit according to the preset invention; FIG. 12B is an enlarged partial cross sectional view taken along a line b—b of FIG. 12A; FIG. 12C is an enlarged partial cross sectional view taken along a line C—C of FIG.  12 A. In the sixth embodiment, a protecting layer is formed over portions of the conductive-pattern layers  25  in the elastic portion R. The protecting layer comprises a conducting layer  37  and an insulating layer  38 . 
     In order to make the present embodiment, a copper base layer is formed on the insulating layer  30  in the process shown in FIG.  6 B- 3 - 6 . The conductive layer  37  made of copper is then formed by means of electro plating, and the layer  37  is patterned. Polyimide resin is coated over the conductive layer  37  so as to form the insulating layer  38 . Preferably, the insulating layer  30  formed over the conductive-pattern layers  25  is formed with a relatively great thickness so that the insulating layer  30  can be flattened and smoothed by means of surface polishing. The conductive layer  37  has a relatively large width B to cover the conductive-pattern layers  25 , and has a length C which covers the length of the elastic portion R as shown in FIG.  12 A. 
     In the present embodiment, the roller  35  exerts a pressing force onto the conductive layer  37  which has a relatively high strength, and thus the pressing force is uniformly dispersed onto the conductive layer  37 . Accordingly, damage to the conductive-pattern layers  25  is prevented when the spring arm  1  is bent by the roller  35 . 
     FIG. 13A is a perspective view of a seventh embodiment of a magnetic head suspension unit according to the present invention. In the seventh embodiment, extra conductive-pattern layers  25   s  are formed. The extra conductive-pattern layers  25   s  are formed along each of the conductive layers  25 . Both ends of each of the additional conductive-pattern layers  25   s  are connected to the ends of the respective conductive-pattern layers  25  at corresponding connection parts  40  and  41 . Accordingly, if one of the conductive-pattern layers  25  is damaged to lose continuity, the corresponding extra conductive-pattern layer  25   s  serves the same function as the damaged conductive-pattern layer  25 . Therefore, a reliable connection can be realized. 
     FIG. 13B is a variation of the seventh embodiment according to the present invention. In this variation, each of the conductive-pattern layers  25  has two paths along the straight portion thereof within the elastic portion R. One of the paths serves as the extra conductive-pattern layer  25   s.    
     In all the above-mentioned embodiments and variations thereof, although the bent portions are formed by a press method using a roller, other method using a mold press or laser may be used. 
     Since the spring arm  1  according to the above-mentioned embodiments is mounted on a member of the magnetic head positioning mechanism, as shown in FIG. 2, the magnetic disk drive can reliably transmit recording/reproducing signals through the spring arm. 
     A description will now be given, with reference to FIG.  14  and FIGS. 15A and 15B, of an eighth embodiment according to the present invention. FIG. 14 is a perspective view of the eighth embodiment of a magnetic head suspension unit according to the present invention. In FIG. 14, parts that are the same as the parts shown in FIG. 1A are given the same reference numerals, and descriptions thereof will be omitted. FIG. 15A is a perspective view of the magnetic head h shown in FIG. 14; FIG. 15B is a cross sectional view taken along a line b—b of FIG.  15 A. 
     In the eighth embodiment according to the present invention, the core slider  4  is mounted on the gimbal  3  by adhesive  42  having a high insulating effect. The core slider  4  may instead be directly mounted on the end  1   b  of the spring arm  1 . Although, in the prior art, the core slider is also mounted by adhesive having an insulating effect, the electric resistance between the core slider  4  and the gimbal  3  is low because the adhesive layer is very thin. Accordingly, the core slider  4  may be at the same potential, that is a ground potential, as the spring arm  1  because the spring arm  1  is grounded. If a high voltage static electricity is generated in the thin-film coil of the magnetic head element  5 , the insulating layer between the thin-film coil and the magnetic pole is damaged, resulting in electric discharge between the thin-film coil and the core slider. 
     In the eighth embodiment, in order to obtain a high resistance between the core slider and the gimbal  3 , a thick layer of the adhesive  42  is provided. It is preferable that the adhesive  42  be a UV cure resin (ultra-violet cure type adhesive). Alternatively, epoxy resin may be used. In the present embodiment, as shown in FIG. 15A, the adhesive  42  comprises an insulating material powder  42   b  mixed in adhesive medium  42   a.  Accordingly, the adhesive  42  can have a high electric resistance, and is formed with a relatively great thickness, and thus the insulation between the core slider  4  and the gimbal  3  is improved. 
     FIG. 16 is an exploded view of an essential part of a ninth embodiment of a magnetic head suspension unit according to the present invention. In the ninth embodiment, the core slider  4  is mounted on the gimbal  3  or the end  1   b  of the spring arm  1  via an insulator  43 . In the present embodiment, the insulator  43  is formed by applying insulating resin such as a photoresist onto a surface of the core slider  4 . The core slider is mounted on the gimbal  3  by applying adhesive  44  onto the insulator  43 . Alternatively, as shown in FIG. 17, the insulator  43  may be applied onto a mounting surface of the gimbal  3 . 
     FIG. 18 is a perspective view of an essential part of a tenth embodiment according to the present invention. In FIG. 18, a magnetic head comprising the magnetic head elements  5  and a core slider  4   i  is shown. Unlike the conventional magnetic head, the core slider  4   i  is made of an insulating material such as SiO 2 . Accordingly, the discharge as described in relation to the conventional magnetic head can be eliminated. 
     FIG. 19 is an exploded view of an eleventh embodiment of a magnetic head suspension unit according to the present invention. I the present embodiment, the magnetic head suspension unit is mounted on a driving arm  13  of the magnetic head driving mechanism via an insulating member  45 . The insulating member has screw holes  46  into which screws for fastening the magnetic head suspension unit to the driving arm  13  are inserted. The screws are made of synthetic resin or metal screws covered with synthetic resin. Accordingly, the spring arm  1  is insulated from the driving arm  13 , which may be grounded. Alternatively, the spacer  2  may be made of an insulating material. 
     In the present embodiment, since the spring arm is not electrically connected to the driving arm  13 , which may be grounded, no electric discharge occurs between the core slider  4  and the magnetic pole. 
     FIG. 20A is a perspective view of a spring arm of a twelfth embodiment of a magnetic head suspension unit according to the present invention; FIG. 20B is an enlarged cross sectional view showing a mounting structure of the core slider shown in FIG.  20 A. In the present embodiment, a gimbal  24  formed on the spring arm  1  has a hole  47  in the center thereof. As shown in FIG. 20B, the core slider  4  is mounted on the gimbal  24  by adhesive  48  so that the hole  47  is filled with the adhesive  48 . Since the hole is formed in the gimbal  24 , the gimbal can be easily bent, if bending stress is applied to the gimbal  24  due to a difference in thermal expansion between the core slider and the gimbal  24 . Accordingly, bending stress applied to the core slider  4  is reduced since the gimbal  24  is bent instead of the core slider  4 . This feature is important when a thin and miniaturized core slider is used. 
     Variations of the hole  47  are shown in FIGS. 21A through 21F. A plurality of holes  47  may be provided, and each hole may have a rectangular shape. 
     In the present embodiment, the hole  47  is filled with a part of the adhesive applied between the core slider  4  and the gimbal  24 , so that the strength of the adhesion between the core slider  4  and the gimbal  24  is increased. Additionally, if the UV cure resin is used, an ultra-violet beam can be irradiated through the hole  47 , which effectively cures the UV cure resin, and thus the strength of the cured UV cure resin can be improved. 
     It should be noted that although the gimbal  24  is integrally formed with the spring arm  1 , the gimbal  24  may be formed separately from the spring arm  1 ; that is, it may be fixed to the spring arm  1  by means of welding described in regard to the conventional magnetic head suspension unit shown in FIG.  1 B. 
     FIG. 22A is a perspective view of a spring arm of a thirteenth embodiment of a magnetic head suspension unit according to the present invention; FIG. 22B is an enlarged cross sectional view of a mounting structure of the core slider shown in FIG. 22A; FIG. 22C is an enlarged cross sectional view showing a variation of the mounting structure shown in FIG.  22 B. In the present embodiment, an opening  49  is provided in the gimbal  24 , into which opening the core slider is inserted. The opening  49  is slightly larger than the outer dimension of the core slider  4 . 
     The core slider  4  is mounted in a state where side faces of the slider core  4  is fixed, as shown in FIG. 22B, by adhesive  50  to the outer edge of the opening  49 . Alternatively, as shown in FIG. 22C, the core slider  4  may be formed to have a step in its side surface so that dimension L 2  is larger than dimension L 1 . The dimension of the opening is determined to be a value between L 1  and L 2 . The adhesive such as UV cure resin is applied to the outer edge of the opening after the core slider  4  is inserted into the opening  49 . An ultra-violet beam is, then irradiated from a direction indicated by an arrow in FIG. 22C so as to cure the UV cure resin. 
     In the present embodiment, since the core slider  4  is supported at the side surfaces thereof, stress generated by thermal expansion of the gimbal  24  is lessened. Accordingly, deformation of the core slider  4  due to the thermal expansion of the gimbal can be efficiently prevented. 
     It should be noted that the magnetic heads shown in FIGS. 20A and 22A are formed with an MR element formed by means of thin-film technology. Thin-film type magnetic head elements are formed on the MR element. However, the present invention is not limited to the specific magnetic head, and a conventional thin-film type magnetic head or a monolithic type magnetic head may be used. 
     A description will now be given, with reference to FIG. 23, of a magnetic head suspension unit  120  according to a fourteenth embodiment of the present invention. 
     FIG. 24 shows a 3.5-inch type magnetic disk drive  1220  to which the magnetic head suspension unit  120  is applied. The magnetic disk drive  1220  has an enclosure  1221  in which a 3.5-inch magnetic disk  1222 , a head positioning actuator  1223  and other parts are housed. 
     A suspension (load beam)  121  made of stainless steel is fixed to an arm  122  of the actuator  223 . The suspension  121  has a curved bent portion  123  generating elasticity. In this regard, the curved portion  123  of the suspension  121  is also referred to as an elastic portion  123  in the following description. The suspension  121  has a stiffness portion  24  extending from the elastic portion  123 , and ribs  121   a.  The elastic portion  123  provides a magnetic head slider (core slider)  135  with a load in a direction in which the magnetic head slider  135  moves and comes into contact with a magnetic disk  1222 . The suspension  121  has a uniform thickness of, for example, approximately 25 μm, which is equal to one-third of the thickness of a suspension of a 3380-type (IBM) head suspension unit. 
     It is desirable that the width W 1  of the suspension  121  is made as small as possible, desirably 4 mm or less. This is because the resonance frequency of vibration of the suspension  121  is prevented from lowering. 
     A gimbal  125  is integrally formed in the suspension  121  so that the suspension  121  and the gimbal has a one-piece construction which uses a plate. The gimbal  125  includes a pair of C-shaped openings  126  and  126  facing each other in the longitudinal direction of the suspension  121 . Two slits  128  and  129  are formed in the suspension  121  along respective sides of the suspension  121 . 
     The gimbal  125  includes a magnetic slider fixing portion  130 , a first pair of beam portions  131  and  132 , and a second pair of beam portions  133  and  134 . The magnetic head slider fixing portion  130  has large surface dimensions enough to fix the magnetic head slider  135  thereon, and has the same dimensions as the magnetic head slider  135  (a=1.6 mm, b=2.0 mm). However, it is possible for the slider fixing portion  130  to have an area less than the magnetic head slider  135  when a sufficient adhesive strength can be obtained. 
     The magnetic head slider  135  is a light weight structure type slider, which has been proposed in Japanese Patent Laid-Open Application No. 4-228157. The proposed slider has a flat back surface opposite to a disk facing surface. The flat back surface of the slider is fixed to the fixing portion  130  by means of an adhesive, which can be an insulation adhesive or an adhesive including an insulator (for example, insulator power). In this case, the slider  135  is located so that the center thereof corresponds to the center of the fixing portion  130 . It is also possible to use other types of sliders. 
     The beam portions  131  and  132  extend outwardly from the respective sides of the fixing portion  130  along a line (suspension width direction line)  138 , which passes through the center of the fixing portion  130  (the above center is also the center of the slider  135 ), and crosses a longitudinal center line  137  of the suspension  121  at a right angle. Each of the beam portions  131  and  132  has a length  1   1 . 
     The beam portion  133  extends from the beam portion  131  towards the respective sides of the beam portion  131  so that the beam portion  133  crosses the beam portion  131  at a right angle and extends parallel to the line  137 . Similarly, the beam portion  134  extends from the beam portion  132  towards the respective sides of the beam portion  132  so that the beam portion  134  crosses the beam portion  132  at a right angle and extends in parallel with the line  137 . The beam portion  133  is joined to portions  140  and  141  of the suspension  121  in the periphery of the gimbal  125 . Similarly, the beam portion  134  is joined to portions  142  and  143  of the suspension  121  in the periphery of the gimbal  125 . In other words, the beam portion  133  extends from the portions  140  and  141  of the gimbal  125 , and the beam portion  134  extends from the portions  142  and  143  of the gimbal  125 . The distance between the center of the beam portion  133  and one of the two ends thereof is 1 2 . Similarly, the distance between the center of the beam portion  134  and one of the two ends thereof is also 1 2 . 
     The beam portion  133  and the beam portion  131  form a T-shaped beam  139 A. Similarly, the beam portion  134  and the beam portion  132  form a T-shaped beam  139 B. The beam portions  131 ,  132 ,  133  and  134  form an H-shaped beam. It will be noted that the fixing portion  130 , the first pair of beams  131  and  132 , and the second pair of beams  133  and  134  are portions of the suspension  121 . 
     The length l 1  of the first pair of beams  131  and  132  is limited by the width W 1  of the suspension  121 . As the width W 1  of the suspension  121  is increased, the resonance frequency of a bend and twist of the suspension  121  becomes lower, and the flying characteristics of the slider  135  are degraded. For these reasons, the width W 1  cannot be increased. However, according to the fourteenth embodiment of the present invention, it is possible to increase the length l 2  of the second pair of beams  133  and  134  without being limited by the width W 1  of the suspension  121 . The second pair of beams  133  and  134  is formed so that l 2 &gt;l 1 . That is, each of the T-shaped beams  39 A and  39 B has a leg portion and an arm portion longer than the leg portion. 
     When a waviness of the magnetic disk being rotated is present or dust adheres to the magnetic disk, the magnetic head slider  135  is rotated in a pitching direction indicated by an arrow  144  in a state in which the first pair of beams  131  and  132  and the second pair of beams  133  and  134  are bent. At this time, a twist deformation occurs in the first pair of beams  131  and  132  of the gimbal  125 , and a bend deformation occurs in the second pair of beams  133  and  134 . 
     As indicated by an arrow  145 , the magnetic head slider  135  is rotated in a rolling direction also. At this time, bend deformations occur in the beams  131  and  132  in the respective directions opposite to each other, and bend deformations occur in the beams  133  and  134  in the respective directions opposite to each other. 
     FIG. 25 shows a resonance mode of the first-order bend. A deformation occurs in the elastic portion  123  formed at the root of the suspension  121 , and the first pair of beams  131  and  132  and the second pair of beams  133  and  134  are deformed in the same direction. 
     FIG. 26 shows a resonance mode of the first-order twist. A twist deformation occurs in the elastic portion  123  formed at the root of the suspension  121  in such a manner so the right and left portions of the elastic portion  123  have different heights. The beam located on the right side of the gimbal  125  is deformed so as to be formed into a convex shape facing upwards. The beam located on the left side of the gimbal  125  is deformed so as to be shaped into a convex facing downwards. When the lengths l 1  and l 2  are selected so that the length l 2  is equal to three or four times the length l 1 , the rotation stiffness responses of the slider in the pitching and rolling directions become sufficiently soft and are almost the same as each other. 
     As shown in FIG. 23, a composite type magnetic head  148  and four terminals  1100 A,  1100 B,  1100 C and  1100 D are provided in the magnetic head slider  135 . The magnetic head  148  includes an MR head for reproduction and an interactive type head for recording, these heads being integrated with each other. The magnetic head  148  is located at a rear end surface of the magnetic head slider  135  in a relative movement direction  146  with respect to the magnetic disk  1222 . 
     As shown in FIGS. 27 and 28, lead wires  115 A,  115 B,  115 C and  115 D are connected to the terminals  1100 A,  1100 B,  1100 C and  1100 D, respectively. Each of the lead wires  115 A through  115 D has a diameter of, for example, 30 μm. The lead wires  115 A- 115 D are laid on the side opposite to the side on which the magnetic head slider  135  is mounted, and are attached to a center portion  36  of the fixing portion  130  by means of an adhesive  116 , which can be an insulation adhesive or an insulator containing an insulator. Further, the lead wires  115 A- 115 D extend along the longitudinal center line  137  of the suspension  121  towards the base portion of the suspension  121 , and are fixed thereto at two points by means of the adhesive  116 . 
     Reference numbers  117   −1 ,  117   −2  and  117   −3  respectively indicate a first fixing point, a second fixing point and a third fixing point at which the lead wires  115 A through  115 D are fixed by means of the adhesive  116 . The first fixing point  117   −1  moves in accordance with movement of the magnetic head slider  135 . Hence, it is unnecessary to be concerned about the stiffness of portions of lead wires  115 A through  115 D between the terminals  1100 A- 1100 D and the first fixing point  117   −1  and to provide additional lengths of the lead wires  115 A- 115 D. In FIG. 27, such additional lengths of the lead wires  115 A- 115 D are not provided. The distance between the first fixing point  117   −1  and the second fixing point  117   −2  is long, and the stiffness of the lead wires  115 A- 115 B between the fixing points  117   −1  and  117   −2  little affects the rotation stiffness of the gimbal  125 . 
     The magnetic head suspension unit  120  has the following features. First, the rotation stiffness of the gimbal  125  is considerably small because of the characteristics of the T-shaped beams. Second, the gimbal  125  is supported at the four points  140 - 143 , and hence, the resonance frequency of vibration of the gimbal  125  is high even when the second pair of beams  133  and  134  is long. Third, the end of the suspension  121  can be formed so that it has a small width W 1 , and hence the resonance frequency of vibration of the suspension  121  is high. Fourth, the flying stability of the magnetic head slider  135  is excellent due to the above first, second and third features. The fifth feature of the mechanism  120  is such that the first pair of beams  131  and  132  has a short length l 1  and is formed in the same plane. Hence, the first pair of beams  131  and  132  has a large strength with respect to force received in the contact start/stop operation, and a shear failure does not easily occur in the beams  131  and  132 . The sixth feature of the mechanism  120  is such that the stiffness of the lead wires  115 A- 115 D does not affect the rotation stiffness of the gimbal  125 . 
     As has been described above, the gimbal  125  is formed so that a pair of T-shaped beams (which form an H-shaped beam) is provided with respect to the center of the gimbal  125 , and hence a low rotation stiffness and a high resonance frequency are achieved. More specifically, the rotation stiffness of the mechanism  120  becomes one-third of that of the aforementioned IBM 3380 type head suspension unit, while the resonance frequency of the mechanism  120  is as high as that of the IBM 3380 type head suspension unit. As a result, it becomes possible to stably fly a compact slider having a low airbearing stiffness. 
     Tables 1 and 2 show characteristics of the head suspension unit  120  according to the fourteenth embodiment of the present invention supporting a 2 mm-length slider, and the IBM 3380 type head suspension unit supporting which a 3.2 mm-length slider. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 COMPARISON OF STIFFNESS 
               
               
                 (static characteristics by computer simulation) 
               
            
           
           
               
               
               
               
            
               
                   
                 Stiffness 
                 1st embodiment 
                 3380 type 
               
               
                   
                   
               
               
                   
                 pitch stiffness 
                 1.5 grf cm/rad 
                 9.4 grf cm/rad 
               
               
                   
                 roll stiffness 
                 1.5 grf cm/rad 
                 5.1 grf cm/rad 
               
               
                   
                 up/down stiffness 
                 0.55 grf/mm 
                 2.4 grf/mm 
               
               
                   
                 equivalent weight ratio 
                 0.74 
                 0.72 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 COMPARISON OF RESONANCE FREQUENCY 
               
               
                 (dynamic characteristic by computer simulation) 
               
            
           
           
               
               
               
               
            
               
                   
                 Stiffness 
                 1st embodiment 
                 3380 type 
               
               
                   
                   
               
               
                   
                 1st bend 
                 2.1 kHz 
                 2.1 kHz 
               
               
                   
                 1st twist 
                 2.3 kHz 
                 2.6 kHz 
               
               
                   
                 in-plane 
                 8.5 kHz 
                 5.7 kHz 
               
               
                   
                   
               
            
           
         
       
     
     In order to make the equivalent weight ratio ((supporting spring equivalent weight)/(slider weight) of the fourteenth embodiment equal to that of the IBM 3380 type mechanism, the total length of the suspension unit is short (10 mm), which is approximately half of that of the IBM 3380 type mechanism. Further, the thickness of the suspension  121  of the fourteenth embodiment is 25 μm, which is approximately one-third of that of the IBM 3380 type mechanism. 
     Table 1 shows data obtained by computer simulation. More specifically, Table 1 shows the pitch stiffness and roll stiffness of the gimbal  125  of the fourteenth embodiment, and the up/down stiffness of the suspension  121  thereof. Further, Table 1 shows the pitch stiffness and the roll stiffness of the gimbal of the IBM 3380 type mechanism, and the up/down stiffness of the suspension thereof. It can be seen from Table 1 that the rotation stiffness equal to one-third of the gimbal of the IBM 3380 type mechanism can be obtained by optimizing the width and length of the grooves in the gimbal  125 . 
     Table 2 shows the resonance frequencies of the fourteenth embodiment and the conventional IBM 3380 type mechanism obtained by a computer simulation. The resonance frequencies of the fourteenth embodiment are similar to those of the IBM 3380 type mechanism. 
     As will be seen from the above, the magnetic head suspension unit according to the fourteenth embodiment of the present invention has a low stiffness and a high resonance frequency. 
     A description will now be given of a fifteenth embodiment of the present invention. In the following description, parts that are the same as those shown in FIG. 23 are given the same reference numbers. 
     FIG. 29 shows a magnetic head suspension unit  150  according to the fifteenth embodiment of the present invention. The mechanism  150  includes a gimbal  151 . The gimbal  151  is formed so that the gimbal  125  shown in FIG. 23 is rotated about the center  136  by 90°. Two T-shaped beams  152  and  153  are arranged in the longitudinal direction of the suspension  121 . 
     FIG. 30 shows a magnetic head suspension unit  160  having a gimbal  161  according to a sixteenth embodiment of the present invention. The gimbal  161  has the aforementioned first pair of beams  131  and  132 , and a second pair of beams  33 A and  34 A. The beam  133 A and the beam  131  form an acute angle α. Similarly, the beam  134 A and the beam  132  form an acute angle equal to the acute angle α. With the above structure, it becomes possible to form, without increasing the width W 1  of the suspension  121 , the second pair of beams  133 A and  134 A so that the length 2×l 2a  thereof is greater than the length 2×l 2  of the second pair of beams  133  and  134  shown in FIG.  23 . Further, it is possible to narrow the end of the suspension  121 . Hence, the rotation stiffness of the gimbal  161  is less than that of the gimbal  125  shown in FIG.  123 . Thus, the magnetic head slider  135  in the sixteenth embodiment can be more stably flied than that in the fourteenth embodiment shown in FIG.  23 . 
     FIG. 31 shows a magnetic head suspension unit  170  having a gimbal  171  according to a seventeenth embodiment of the present invention. A magnetic head slider  135 A of the mechanism  170  includes flanges  172  and  173  formed on the respective sides of the slider  35 A. A magnetic head slider fixing portion  130 A of the gimbal  171  includes an opening  174  having a size corresponding to the magnetic head slider  135 A. The opening  174  is of a rectangular shape defined by a rectangular frame  176 . As shown in FIG. 31, the magnetic head slider  135 A engages the opening  174 , and the flanges  172  and  173  are made to adhere to the frame  176  by means of an insulation adhesive or an adhesive containing an insulator. In this manner, the magnetic head slider  135 A is fixed to the magnetic head slider fixing portion  130 A. 
     As shown in FIG. 32, the center G of gravity of the magnetic head slider  135 A is substantially located on the surface of the suspension  121 . Hence, in a seek operation, the magnetic head slider  135 A is moved by exerting a force on the center G of gravity. Thus, an unnecessary rotation force about the center G of gravity of the magnetic head slider  135 A does not occur, and the unbalance of the magnetic head slider  135 A is reduced. As a result, the magnetic head slider  135 A can stably fly in the seek operation. 
     Further, the height of the magnetic head assembly can be reduced. Hence, it is possible to laminate layers of the head at reduced intervals and to provide an increased number of disks per unit length. As a result, it is possible to increase the volume storage density of the magnetic disk drive and hence the storage density. 
     FIG. 33 shows a magnetic head suspension unit  180  having a magnetic head slider  135 B according to an eighteenth embodiment of the present invention. The magnetic head slider  135 B has a flange  181  formed around the circumference thereof. The magnetic head slider  135 B engages the opening  174 , and the flange  181  is adhered to the magnetic head slider fixing portion  130 A by means of an adhesive which can be an insulation adhesive or an adhesive containing an insulator. That is, the eighteenth embodiment of the present invention differs from the seventeenth embodiment thereof in that the whole circumference of the magnetic head slider  135 B is made to adhere to the fixing portion  130 A. Hence, the adhesive strength is increased and the reliability of the magnetic head suspension unit is improved. 
     FIG. 34 shows a magnetic head suspension unit  190  according to a nineteenth embodiment of the present invention. FIG. 35 shows a free end of a suspension of the magnetic head suspension unit  190 . The mechanism  190  is designed so that it does not have any influence of the stiffness of lead wires, which affect flying of the slider having a low airbearing stiffness. For example, when, in the case where four lead wires are connected between the slider and the suspension (see FIG.  27 ), each of the lead wires has a diameter of 30 μm and has an additional length (free length) of 1 mm, the rotation stiffness of the gimbal is approximately five times that of the gimbal in which there is no lead wire. This degrades the flying stability of the slider. 
     The magnetic head suspension unit  190  has wiring patterns  191 ,  192 ,  193  and  194 , which are formed by patterning a copper thin film formed by, for example, plating by means of the photolithography technique. The wiring patterns  191 - 194  extend on a central portion of the lower surface of the suspension  121  in the longitudinal direction. Each of the wiring patterns  191 - 194  is approximately 5 μm thick and 50 μm wide. The thickness and width of the wiring patterns depend on the resistance of the conductive pattern and the capacity of the suspension  121 . 
     Terminals  195 A- 195 D made of copper are formed on the base portion of the suspension  121 . Further, terminals  196 A- 196 D are formed in a terminal area  130   a  of the magnetic head slider fixing portion  130  of the gimbal  125 . The tops of the terminals  195 A- 195 D and  196 A- 196 D are plated by, for example, Au. This plating contributes to preventing exposure of copper and improving the bonding performance. Ends of the wiring patterns  191 ,  192 ,  193  and  194  are respectively connected to the terminals  195 A,  195 B,  195 C and  195 D. The other ends of the two wiring patterns  191  and  192  extend along the beams  133 A and  131 , and are connected to the terminals  196 A and  196 B, respectively. The other ends of the wiring patterns  193  and  194  extend along the beams  134 A and  132  and are connected to the terminals  196 C and  196 D, respectively. 
     As shown in FIG. 36, the wiring patterns  191 ,  192 ,  193  and  194  are electrically insulated from the suspension  121  by means of an insulating film  197 , and are covered by a protection film  198 . The insulating film  197  and the protection film  198  are made of photosensitive polyimide and are grown to a thickness of approximately 5 μm. The insulating film  197  and the protection film  198  are respectively patterned by the photolithography technique. The thickness of the insulating film  197  is determined on the basis of a capacitance between the conductive pattern (made of Cu) and the suspension (made of stainless steel). 
     As will be described later, polyimide has heat-resistance enough for an annealing process. Since polyimide has photosensitivity, it can be easily patterned. Further, the polyimide films  197  and  198  have corrosion resistance, and excellent reliability. 
     It is likely that the terminals  195 A- 195 D and  196 A- 196 D are etched because these terminals are not covered by the protection film  198 . In order to prevent the terminals  195 A- 195 D and  196 A- 196 D from being etched, the surfaces of these terminals are covered by an Au film (not shown) having a thickness of approximately 1 μm formed by plating or vapor deposition. 
     As shown in FIG. 37, the magnetic head slider  135  is made to adhere to the fixing portion  130  by means of an adhesive which can be an insulation adhesive or an adhesive containing an insulator. The terminals  196 A- 196 D are located at a right angle with respect to terminals  1100 A- 1100 D of the magnetic head  148  formed on the end surface of the magnetic head slider  135 , and are respectively connected to the terminals  1100 A- 1100 D by means of Au balls  1101 A- 1101 D. The Au balls  1101 A- 1101 D are formed by means of, for example, a gold ball bonding device. In order to facilitate bonding, the terminals  196 A- 196 D and terminals  1100 A- 1100 D are located as shown in FIG.  37 . In order to facilitate a crimp operation on the Au balls  1101 A- 1101 D, the terminals  1100 A- 1100 D are long in the direction of the height of the magnetic head slider  135  and are located so that these terminals  1100 A- 1100 D face the terminals  196 A- 196 D in the state where the head slider  135  is fixed to the fixing portion  130 . 
     In addition to FIG. 37, FIGS. 55-59 illustrate an embodiment with a bonding ball connection in more detail. 
     FIG. 55 is a structural diagram of a magnetic disk apparatus to which another embodiment of the present invention directed to bonding balls is adapted, FIG. 56 is a cross section of the structure in FIG. 55, FIG. 57 is a front view of an actuator in FIG. 55, FIG. 58 is an explanatory diagram of the seventeenth embodiment of this invention in FIG. 55, and FIG. 59 is a diagram for explaining how to connect the embodiment. 
     FIG. 55 illustrates a magnetic disk apparatus which allows a head to float onto a magnetic disk to execute magnetic recording. 
     Provided on a base  60 - 1  of the apparatus are a 3.5-in magnetic disk  5 - 1 , which rotates around a spindle shaft  64 - 1 , and a magnetic circuit  63 - 1 . An actuator  4 - 1  is mounted rotatable around a rotary shaft  62 - 1 . 
     A coil  41 - 1  is provided at the rear portion of this actuator  4 - 1 , as shown in FIGS. 59,  56  and  57 , and the coil  41 - 1  is located in the magnetic circuit  63 - 1 . 
     As shown in FIG. 56, nine arms  3 - 1  are formed at the front portion of the actuator  4 - 1 , each arm  3 - 1  is formed at the front portion of the actuator  4 - 1 , and each arm  3 - 1  is provided with support plate (suspension)  7 - 1  which has a magnetic head core (core slider)  8 - 1  provided at the distal end. 
     This actuator  4 - 1 , together with the coil  41 - 1  and magnetic circuit  63 - 1 , form a linear actuator. When current flows through the coil  41 - 1 , the actuator  4 - 1  rotates around the rotary shalt  62 - 1  to move the magnetic head core  8 - 1  for a seek operation in a direction perpendicular to the tracks of the magnetic disk  5 - 1  (radial direction). 
     In FIG. 58, “ 7 - 1 ” is a support plate (suspension) made of metal having a spring property, such as stainless. An insulating layer is coated on the support plate, and a pair of wiring patterns  71 - 1  and suspension connector terminals  72 - 1  are formed thereon by a copper pattern. The support plate  7 - 1  has its one end fixed to the arm  3 - 1  by laser spot welding or the like. 
     “ 8 - 1 ” is a magnetic head core (core slider) which has a pair of core slider connector terminals  82 - 1  and a thin-film magnetic head  81 - 1  provided on the sides. 
     When the magnetic head core  8 - 1  is mounted on the support plate  7 - 1 , the connector terminals  72 - 1  of the support plate  7 - 1  and the connector terminals  82 - 1  of the magnetic head core  8 - 1  are fixed with the positional relationship as shown in FIG.  58 (B) and  59 (A), and gold balls W about 0.1 mm in diameter are made to contact both gold-plated connector terminals  82 - 1  and  72 - 1  and are subjected to pressure bonding and ultrasonic bonding by a ball bonder, the connector terminals  82 - 1  and  72 - 1  are electrically and mechanically connected via the gold balls W due to intermetal bonding. In this example, the magnetic disk  5 - 1  is located upward of the diagram. 
     When the support plate  7 - 1  is provided with the wiring patterns  71 - 1  and connector terminals  72 - 1  while the magnetic head core  8 - 1  is provided with the connector terminals  82 - 1 , they can be connected by gold ball bonding. Therefor, even the minute magnetic head core  8  can easily be connected, thus accomplishing the miniaturization of the magnetic head assembly. 
     Further, unlike lead wires, wiring is not necessary, so that difficult wiring at the minute suspension is unnecessary, further facilitating the assembling. 
     Furthermore, the number of components is reduced to make the assembling easier and accomplish a small magnetic head assembly. 
     FIG.  59 ( b ) shows a modification of the seventeenth embodiment in which a dummy terminal  83 - 1  is provided at the flow-in side of the magnetic head core  8 - 1 , and a dummy terminal  73 - 1  is provided on the wiring pattern  71 - 1  of the support plate  7 - 1  accordingly. With gold balls W about 0.1 mm in diameter in contact with both gold-plated connector terminals  83 - 1  and  73 - 1 , pressure bonding and ultrasonic bonding are performed by a ball bonder, those connector terminals  83 - 1  and  73 - 1  are connected together via the gold balls W due to intermetal bonding. 
     Accordingly, the magnetic head core  8 - 1  has both ends connected by the gold balls W to the support plate  7 - 1 , so that adhesion of the magnetic head core  8 - 1  to the support plate  7 - 1  is unnecessary and the connection can be made by the ball bonding step alone, further facilitating the assembly. 
     Although the lead wires are connected to the arm side terminals (see FIG.  58 (A)) of the wiring patterns  71 - 1  of the support plate  7 - 1  before connecting to the arm  3 - 1  in this example, this wiring is easy because the arm  3 - 1  is relatively large. 
     The wiring patterns  191 - 194  bypass holes  1102 A,  1102 B and  1102 C, as shown in FIG.  34  and extend up to an area close to the head slider  135 . The hole  1102   c  is used to fix the suspension  121  to the arm  122  (not shown in FIG.  34 ). The holes  1102 A,  110 B and  1102 C are sized such that a tool can be inserted therein. 
     As shown in FIGS. 34 and 35, dummy patterns  1103 A- 1103 D and  1104 A- 1104 D are provided so that these dummy patterns are symmetrical to the bypassing portions of the wiring patterns  191 - 194  with respect to the holes  1102 A and  1102 B. The insulating film  197  and the protection film  198  are provided for the dummy patterns  1103 A- 1103 D and  1104 A- 1104 D in the same manner as the wiring patterns  191 - 194 . The dummy patterns  1103 A- 1103 D and  1104 A- 1104 D are provided in order to balance the mechanical stiffness of the suspension  121  in the direction of the width of the suspension  121 . 
     As shown in FIG. 35, the wiring patterns  191 - 194  are arranged so that these patterns form a loop. This loop functions as an antenna, which receives noise components contained in the head signals. As the size of the loop is increased, the degree of the noise components is increased. In order to reduce the size of the loop, the wiring patterns  191  and  192  respectively connected to the terminals  196 A and  196 B are arranged between the hole  1102 A and the magnetic head slider  135 , and all the wiring patterns  191 - 194  are gathered in the vicinity of the hole  1102 A. In order to balance the stiffness in the direction of the width of the suspension, the dummy patterns  1104 A- 1104 D are formed. For the same reason as above, the dummy patterns  1103 A- 1103 D are formed in the vicinity of the hole  1102 B. 
     As shown in FIG. 35, auxiliary films  1106  and  1107  having a belt shape are formed along the right and left ends of the suspension  121 . The auxiliary films  1106  and  1107  are provided in order to receive a clamping force generated when the suspension  121  is clamped in a bending process which will be described later. Such a clamping force is also received by the wiring patterns  191 - 194 . The clamping force is distributed so that the clamping force is exerted on not only the wiring patterns  191 - 194  but also the auxiliary films  1106  and  1107 . Hence, it is possible to prevent the wiring patterns  191 - 194  from being damaged. 
     As shown in FIGS. 34 and 35, a convex dummy pattern  1108  is provided in order to prevent an adhesive from flowing from the fixing portion  130  when the slider  135  is fixed to the fixing portion  130  and to prevent the slider  135  from being tilted due to the thickness of the wiring patterns. More particularly, the convex pattern  1108  is used to form a groove in which an insulation adhesive used to fix the slider  135  is saved between the pattern  1108  and the terminals  196 A- 196 D. Further, the convex pattern  1108  is designed to have the same height as the patterns having the terminals  196 A- 196 D. If the dummy pattern  1108  is not used, the slider  135  will be inclined with respect to the fixing portion  130  due to the height of the terminals  194 A- 194 D. This degrades the flying stability of the heads. Further, the use of the convex dummy pattern  1108  increases the height of the adhesive to thus improve the insulation performance. The convex pattern  1108  can be formed by a cooper-plated thin film similar to the wiring patterns  191 - 194 . The protection film  198  covers the convex pattern  1108 . The adhesive is provided on a step part between the wiring patterns and the convex pattern  1108 . 
     The suspension  121  is produced by a process shown in FIG.  38 . First, a pattern formation step  1110  is performed. More particularly, photosensitive polyimide is coated on a stainless plate. The insulating film  197  is formed by the photolithography technique. A copper film is formed by the plating process, the vapor deposition process or the like, and is patterned into the wiring patterns  191 - 194  by the photolithography technique. Thereafter, photosensitive polyimide is coated and is patterned into the protection film  198  and the auxiliary films  1106  and  1107  by the photolithography technique. Polyimide can be coated by a spin-coat process, and is patterned and etched. A thin film, such as a Cr film, can be formed in order to improve the adhesiveness between the insulating film and the Cu film and between the Cu film and the protection film and to improve the reliability of the adhesion. 
     Next, an etching step  111  is performed in order to form the openings  126 - 129  and the holes  1102 A- 1102 C and the outward form of the suspension in the stainless plate. FIG. 39 shows suspensions  1202  before punching for cutting off bridge portions (not shown) to provide pieces, so that the suspensions  1202  are formed in a stainless plate  1201  and arranged in rows and columns. 
     Then, a bending step  1112  is performed by bending the respective ends of each of the suspensions  1202  formed in the stainless plate  1201 , so that ribs  121   a  are formed. The bending step  1112  can be performed by press so that the suspensions  1202  are processed at the same time. 
     Finally, an annealing step  1113  is performed at a temperature of approximately 400° C., so that internal stress can be removed. Further, a slider adhering step and an Au bonding step can be automatically carried out before the suspensions  1202  are punched. Hence, it is possible to automatically perform the production process shown in FIG.  38  and reduce the number of steps and the cost thereof. 
     The suspension  121  can be produced without performing the annealing step  1113 . In this case, as is shown in FIG. 40, the pattern formation step  1110  and the etching step  1111  are performed, and subsequently the slider adhering step and the Au bonding step are carried out. Thereafter, the bending step  1112  is carried out to form the ribs  121   a.    
     As shown in FIG. 41, when interactive type heads  148 A and  148 B for recording and reproduction are used as magnetic heads, the magnetic head slider  135  has the aforementioned two terminals  1100 A and  1100 B. In the gimbal  125 , the two wiring patterns  191 A and  192 A are provided so that these wiring patterns extend on only the beams  132  and  134 A, while two dummy patterns  1210  and  1211  are provided so as to extend on the beam  131  and  133 A in order to balance the mechanical stiffness of the suspension  121  in the direction of the width of the suspension  121 . 
     The magnetic head suspension unit  190  has the following features. 
     First, since the wiring patterns  191 - 194  are formed on the suspension  121 , it is not necessary to provide tubes for passing the lead wires through the suspension  121 . Hence, it is possible to prevent unbalanced force caused by the lead wires and tubes from being exerted on the magnetic head slider  135  and to stably fly the magnetic head slider  135 . 
     Second, due to use of the dummy patterns  1103 A- 1103 D and  1104 A- 1104 D, the rotation stiffness of the suspension  121  does not have polarity. Hence, the magnetic head slider can fly stably. 
     Third, the crimp connection using the Au balls  1101 A- 1101 D enables automatic assembly and non-wire bonding between head terminals and pattern terminals. 
     In the aforementioned embodiments of the present invention, the beams may be curved. 
     A description will now be given of a magnetic head suspension unit suitable for a more compact magnetic disk drive according to a twelfth embodiment of the present invention. 
     FIG. 42 shows a back surface of a magnetic head suspension unit  1230  according to the twelfth embodiment of the present invention. FIG. 43 shows a 1.8-inch-type magnetic disk drive  1231  to which the magnetic head suspension unit  1230  is applied. 
     The magnetic disk drive  1231  has an enclosure  1232  having almost the same dimensions as those of an IC memory card. In the enclosure  1232 , provided are a magnetic disk  1233  having a diameter of 1.8 inches, and an actuator to which two sets of magnetic head suspension units are attached. The magnetic disk drive  1231  is more compact than the magnetic disk drive  1220  shown in FIG.  3 . 
     A magnetic head slider  135 C is made compact in accordance with light-sizing of the magnetic disk drive  1231 . More particularly, dimensions a×b of the magnetic head slider  135 C are 0.8 mm×1.0 mm, and are approximately one-quarter the area of the magnetic head slider  135  shown in FIG.  23 . In order to stably fly the compact magnetic head slider  135 C, it is necessary to considerably reduce the stiffness without decreasing the resonance frequency, as compared with the magnetic head suspension unit  130 . 
     A suspension  1235  shown in FIG. 42 is made of stainless, and has a base portion fixed to an arm  1236  of the actuator  1234  (see FIG.  43 ). The suspension  1235  has a width W 2  of approximately 2 mm, a length L of approximately 9 mm, and a thickness to of approximately 25 μm, and is approximately a half of the volume of the suspension  121  shown in FIG.  23 . The suspension  1235  is diminished, and hence the resonance frequency of bending which will be described later is high. 
     The suspension  1235  is a sheet-shaped piece, and a flat plate piece to which a bending process has not been subjected. Hence, there is no problem of a bending process error which degrades the flying stability of the magnetic head slider. The suspension  1235  includes a suspension main body  1237  and a gimbal  1238  located on the end side of the suspension  1235 . The gimbal  1238  has a substantially U-shaped opening (through hole)  1239  formed in the suspension  1235 . The gimbal  1238  includes a magnetic head slider fixing portion  1240 , a first beam  1241 , a second beam  1242 , a third beam  1244 , and a connecting portion  1243 . 
     The magnetic head slider fixing portion  1240  has a size corresponding to the magnetic head slider  135 C. The first beam  1241  and the second beam  1242  extend along respective longitudinal ends of the suspension  1235  from the end thereof. The connecting portion  1243  extends in the direction of the width of the suspension  1235 , and connects the first beam  1241  and the second beam  1242  together. The third beam  1244  extends from the connecting portion  1243  to the magnetic head slider fixing portion  1240  in the longitudinal direction of the suspension  1235 . The magnetic head slider fixing portion  1240  is connected to the main body  1237  of the suspension  1235  via the third beam  1244 , the connecting portion  1243  and the first and second beams  1241  and  1242 . Hence, the rotation stiffness of the suspension  1230  can be reduced to a small value due to bending of the entire beams. 
     As shown in FIG. 42, holes  1245 ,  1246  and  1247  with which a tool is engaged, and a pair of slits  1248  and  1249  are formed in the main body  1237  of the suspension  1235 . Adjustment slits  1248  and  1249  are used to reduce the rotation stiffness of the suspension. The holes  1245 ,  1246  and  1247  and the slits  1248  and  1249  are formed by etching. The connectors  195 A- 195 D,  196 A- 196 D and the wiring patterns  191 - 194  are formed symmetrically with respect to the longitudinal direction of the suspension  1235 . The magnetic head slider  135 C is made to adhere to the fixing portion  1240 , and the terminals  196 A- 196 D and  1100 A- 1100 D are respectively connected to each other by means of Au balls, as in the case shown in FIG.  37 . 
     The structure shown in FIG. 42 does not use dummy patterns because the length and the width of the suspension  1235  are less than those of the suspension shown in FIG.  34  and the loop formed by the wiring patterns is smaller than that shown in FIG.  34 . However, it is preferable to arrange the wiring patterns and provide the dummy patterns as shown in FIGS. 34 and 35 in order to reduce the noise from the heads. 
     As shown in FIGS. 44A and 44B, the free end of the arm  1236  is bent so that a substantially V-shaped cross section of the arm  1236  is formed in which the “V” is inverted. The free end of the arm  1236  has an upward slant portion  1236   a  and a downward slant portion  1236   b  declined at an angle θ with respect to the horizontal direction. 
     The magnetic disk drive  1231  uses two magnetic head suspension units  1230  so that the single magnetic disk  1233  is sandwiched between the mechanisms  1230 . As shown in FIG. 45, the suspension  1235  causes the magnetic head slider  135 C to come into contact with the magnetic disk  1233  when the magnetic disk  1233  is not being rotated. At this time, the main body  1237  of the suspension  1235  is caused to be bent and elastically deformed. The elastic force stored in the main body  1237  of the suspension  1235  generates a load F 1 , which urges the magnetic head slider  35 C towards the magnetic disk  1233 . 
     Since the arm  1236  is bent in the form of the inverted “V”, a wide gap  1250  can be formed between an end  1236   c  of the arm  1236  and the magnetic disk  1233 , as compared with a case indicated by a two-dot chained line in which the arm  1236  is simply bent downwards. 
     A description will now be given of a moment exerted on the magnetic head slider  135 C by means of the suspension  1235  when the suspension is loaded on the disk. As shown in FIG. 46, the main body  1237  of the suspension  1235  and the third beam  1244  are bent. Hence, a moment is exerted by a center  1251  of the magnetic head slider  35 C. A moment M 1  directed counterclockwise is exerted by the suspension main body  1237  and the first and second beams  1241  and  1242 . A moment M 2  directed clockwise is exerted on the third beam  1244 . The dimensions of the suspension  1235  are selected so that the moments M 1  and M 2  are balanced. For example, the suspension  1235  is 9 mm long, and the gimbal  1238  is 2.5 mm long. Further, the length and width of the main body  1235  of the suspension  1237  are 5.7 mm and 2 mm, respectively. With the above structure, it is possible to stably fly the magnetic head slider  135 C. 
     A description will now be given, with reference to FIG. 42, of pitching and rolling of the magnetic head slider  135 C. 
     (1) Pitching 
     The magnetic head slider  135 C is rotated in the pitching direction indicated by arrow  144  in such a manner that the first, second and third beams  1241 ,  1242  and  1244  and the suspension main body  1237  are bent. At this time, all the beams  1241 ,  1242  and  1244  are bent so as to be deformed in the form of arch shapes. The gimbal  1238  is bent and hence the suspension main body  1237  is bent. Hence, the pitch stiffness can be greatly reduced. 
     (2) Rolling 
     The magnetic head slider  135 C is rotated in the rolling direction indicated by arrow  145  in such a manner that the first and second beams  1241  and  1242  are respectively bent in the opposite directions and the suspension main body  1237  is twisted. At this time, the gimbal  1238  is bent and hence the suspension main body  1237  is bent. Hence, the rolling stiffness can be greatly reduced. 
     A description will now be given of the first-order bend and the first-order twist of the magnetic head suspension unit  1230  obtained when the suspension is vibrated. 
     (1) First-order bend 
     The suspension  1235  is bent and deformed, as shown in FIG.  47 . More specifically, the suspension main body  1237 , and the first, second and third beams  1241 ,  1242  and  1244  of the gimbal  1238  are bent as shown in FIG.  45 . The overall suspension  1235  is formed flexibly, but the resonance frequency of the first-order bend is high, while the stiffness is small. 
     (2) First-order twist 
     The suspension  1235  is twisted as shown in FIG.  48 . The gimbal  1238  is deformed and hence the suspension main body  1237  is deformed. Hence, the overall suspension  1235  is flexibly formed, but the resonance frequency of the first-order twist is high while the stiffness thereof is low. 
     Tables 3 and 4 show characteristics of the magnetic head support mechanism  1230  according to the twelfth embodiment of the present invention and the magnetic head suspension unit  130  of the fourteenth embodiment thereof shown in FIG.  23 . 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 COMPARISON OF STIFFNESS 
               
               
                 (static characteristics by computer simulation) 
               
            
           
           
               
               
               
               
            
               
                   
                 Stiffness 
                 7th embodiment 
                 1st embodiment 
               
               
                   
                   
               
               
                   
                 pitch stiffness 
                 0.44 grf cm/rad 
                 1.5 grf cm/rad 
               
               
                   
                 roll stiffness 
                 0.24 grf cm/rad 
                 1.5 grf cm/rad 
               
               
                   
                 up/down stiffness 
                 0.36 grf/mm 
                 0.55 grf/mm 
               
               
                   
                 equivalent weight ratio 
                 0.76 
                 0.74 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 COMPARISON OF RESONANCE FREQUENCY 
               
               
                 (dynamic characteristics by computer simulation) 
               
            
           
           
               
               
               
               
            
               
                   
                 Stiffness 
                 7th embodiment 
                 1st embodiment 
               
               
                   
                   
               
               
                   
                 1st bend 
                 1.6 kHz 
                 2.1 kHz 
               
               
                   
                 1st twist 
                 4.4 kHz 
                 2.3 kHz 
               
               
                   
                 in-plane 
                 7.1 kHz 
                 8.5 kHz 
               
               
                   
                   
               
            
           
         
       
     
     More particularly, Table 3 the pitch stiffness, the roll stiffness, and the up/down stiffness of the suspension  1235  obtained by means of a computer simulation. It can be from Table 3 that the pitch stiffness and the roll stiffness of the twelfth embodiment of the present invention are approximately one-quarter of those of the fourteenth embodiment thereof. 
     Table 4 shows the resonance frequencies of the fourteenth and twelfth embodiments of the present invention obtained by a computer simulation. It can be seen from Table 4 that the first-order bend resonance frequency, the first-order twist resonance frequency and the lateral resonance frequency are kept very high. 
     It can be seen from Tables 3 and 4 that the magnetic head suspension unit  1230  according to the twelfth embodiment of the present invention has a resonance frequency as high as that of the magnetic head suspension unit  130  according to the fourteenth embodiment, and stiffness much less than that of the mechanism  130 . Hence, the compact magnetic head slider  135 C can be stably flied. 
     In an alternative of the suspension, the base portion of the suspension  1237  is bent, so that the suspension is supported in the same manner as shown in FIG.  23  and the load F 1  shown in FIG. 45 is obtained. In this case, only portions  1255  and  1256  outside of the slits  1248  and  1249  are bent. Hence, unnecessary strain is not exerted on the wiring patterns  191 - 194  located between the slits  1248  and  1249 . 
     A first variation of the gimbal  1238  of the suspension  1235  will be described. A gimbal  1238   −1  shown in FIG. 49 has a first beam  1244   −1  having a long width A, and an opening  1239   −1  having a long length B. First and second beams  1241   −1  and  1242   −1  are long. 
     FIG. 50 shows a second variation  1238   −2  of the gimbal  1238 . The gimbal  1238   −2  has first and second beams  1241   −2  and  1242   −2  each having a small width C. 
     FIG. 51 shows a third variation  1238   −3  of the gimbal  1238 . The gimbal  1238   −3  has first and second variations  1241   −3  and  1242   −3  having a large width D. 
     FIG. 52 shows a fourth variation  1238   −4  of the gimbal  1238 . The gimbal  1238   −4  has a fourth beam  1260  connecting the center of the end of the magnetic head slider fixing portion  1240  and the suspension main body  1237  together. The fourth beam  1260  functions to prevent a deformation of the magnetic head slider fixing portion  1240 , but increases the rotation stiffness. Hence, it is desired that the width of the fourth beam  1260  be as small as possible and the length thereof are as long as possible. 
     FIG. 53 shows a fifth variation  1238   −5  of the gimbal  1238 . The gimbal  1238   −5  has first and second arch-shaped beams  1241   −5  and  1242   −5 . 
     As shown in FIG. 54, a bent connecting plate  1261  is fixed to an arm  1236 A, and the suspension  1235  is fixed to the connecting plate  1261 . Hence, it is not necessary to subject the arm  1236 A to bending stresses. 
     In the variations shown in FIG. 49 through 132, it can be said that the third beam  1244  shown in FIG. 42 has the same width as the fixing portion  1240  and is integrated with the fixing portion  1240 . 
     In the fourteenth through nineteenth embodiments, the load applied to the magnetic head slider is generated by bending the spring portion of the suspension. Alternatively, it is possible to employ the arm fixing structure used in the twelfth embodiment of the present invention in which the spring portion is kept flat. 
     The present invention is not limited to the specifically disclosed embodiments and variations, and other variations and modifications may be made without departing from the scope of the present invention.