Method of forming a head gimbal assembly

Abstract
A method for forming a head gimbal assembly in which the head gimbal assembly and a frame are formed from a continuous piece of laminated material comprised of a first layer, a second layer and a third layer. A plurality of electrical lines are formed in the third layer of the head gimbal assembly and a plurality of electrical line extensions are formed in the third layer of the frame. The slider is positioned at an angle to the frame and a plurality of termination pads on the slider are bonded to the electrical lines. The frame is partially separated from the head gimbal assembly and the relative position of the slider to the head gimbal assembly is changed by an amount sufficient to separate the plurality of electrical lines from the plurality of electrical line extensions.
Description




BACKGROUND OF THE INVENTION




1. Technical Field




The present invention relates to a head gimbal assembly for a magnetic disk file and more specifically to a head gimbal assembly formed from a laminated material in which the electrical lines are formed in one layer of the laminate.




2. Background Information




Magnetic recording disk files that utilize a transducer mounted on a slider for reading and/or writing data on at least one rotatable disk are well-known in the art. In such systems, the slider is typically attached to an actuator arm by a suspension system.




Many suspension systems (also called head gimbal assemblies) include a flexure that is positioned in some manner between the slider and the suspension. For example, R. Watrous, in U.S. Pat. No. 4,167,765, discloses a flexure that is added onto a stiffened member. Blaeser et. al, in U.S. Pat. No. 5,198,945, disclose another design that utilizes the material of the suspension as the flexure.




Systems are known in which the slider is positioned in an open space formed between two flexure arms. For example,

FIG. 6

illustrates a head gimbal assembly described by Johnson et al. in U.S. Pat. No. 5,331,489, in which the slider is positioned between two flexure arms and the electrical attachment to the slider is made by four discrete wires. The discrete wires are terminated to the back of the slider and four wires are utilized to accommodate magnetoresistive (MR) head technology.




The use of solder balls for attaching the slider to a slider support means is known in the art. For example, Ainslie et al., in U.S. Pat. No. 4,761,699, disclose the use of reflowed solder balls for making both the mechanical attachment of the slider to the suspension and the electrical connection of the transducer to the disk file read/write electronics. Additionally, Ainslie et al., in U.S. Pat. No. 4,789,914, disclose a soldering technique for making an electrical attachment of a cable to a transducer on the backside of a slider.




The use of laminated materials for constructing slider suspension systems is also known in the art. For example, Erpelding et al., in U.S. Pat. No. 4,996,623, disclose a suspension system comprised of a sheet of polyimide material sandwiched between two metal layers. U.S. Pat. No. 4,996,623 also discloses that a plurality of conductors can be formed in the copper layer of the suspension for providing electrical connections to the slider.




Additionally, the use of discrete layers for constructing the suspension is also known. For example, G. Oberg, in U.S. Pat. No. 4,819,094, discloses a suspension system in which flexible copper conductors are sandwiched between a pair of polyimide films.




BRIEF SUMMARY OF THE INVENTION




Briefly, the preferred embodiment of the present invention is a head gimbal assembly comprising a slider support member for holding a slider, a load beam for applying a load to the slider and an electrical cable extending along the backside of the load beam.




The head gimbal assembly is a single piece constructed from a laminated material comprised of a conductor layer, a dielectric layer and a support layer. The conductor layer is comprised of a high strength electrically conductive material such as a high strength copper alloy. The dielectric layer is comprised of an electrically insulating material such as a polyimide, Teflon or epoxy. The support layer is comprised of a more rigid material such as stainless steel, titanium or beryllium copper.




The electrical cable is positioned for connection to the backside of a slider and is comprised of the conductor and dielectric layers of the laminated material. The conductor layer is positioned on the dielectric layer and a plurality of elongated strips are formed in the conductor layer, with a space separating each of the elongated strips. The dielectric layer is positioned between the backside surface of the slider and the conductor layer, and between the backside surface of the load beam and the conductor layer, to prevent electrical shorting.




In other embodiments, the electrical lines extend along the backside or frontside of the load beam and are terminated to the trailing edge of the slider.











BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING





FIG. 1

is a schematic side view of a slider suspension system;





FIG. 2

is a cross-sectional view of the slider suspension system taken along the line


2





2


of

FIG. 1

;





FIG. 3

is an isometric view of a slider suspension system;





FIG. 4

is a cross-sectional view of the slider suspension system taken along the line


4





4


of

FIG. 3

;





FIG. 5

is a schematic diagram of a disk file that utilizes a slider suspension system;





FIG. 6

is an isometric view of a head gimbal assembly according to the prior art;





FIG. 7

is an isometric view of a head gimbal assembly according to the present invention;





FIG. 8

is a cross-sectional view of the head gimbal assembly taken along the line


8





8


of

FIG. 7

;





FIG. 9

is a cross-sectional view of the head gimbal assembly taken along the line


9





9


of

FIG. 7

;





FIG. 10

is a cross-sectional view of the head gimbal assembly taken along the line


10





10


of

FIG. 7

;





FIG. 11

is a cross-sectional view of an alternative embodiment of the head gimbal assembly shown in

FIG. 10

;





FIG. 12

is a top view of a head gimbal assembly according to the prior art;





FIG. 13

is a top view of a head gimbal assembly according to the present invention;





FIG. 14

is an isometric view of the head gimbal assembly shown in

FIG. 13

;





FIG. 15

is a cross-sectional view of the head gimbal assembly taken along the line


15





15


of

FIG. 14

;





FIG. 16

is a cross-sectional view of the head gimbal assembly taken along the line


16





16


of

FIG. 14

;





FIG. 17

is a side view of the head gimbal assembly shown in

FIG. 13

;





FIG. 18

is a top view of a frame used in manufacturing a head gimbal assembly according to the present invention;





FIG. 19

is a top view of an alternative embodiment of a head gimbal assembly according to the present invention; and





FIG. 20

is a cross-sectional view of the head gimbal assembly taken along the line


20





20


of FIG.


19


.











DETAILED DESCRIPTION OF THE INVENTION





FIG. 1

is a schematic diagram of a first transducer suspension


10


and a second transducer suspension


14


attached to an actuator arm


18


. The suspensions


10


and


14


are also referred to as head gimbal assemblies.




A first slider


22


is positioned at an end of the first transducer suspension


10


distally to the arm


18


. A second slider


26


is positioned at an end of the second transducer suspension


14


distally to the arm


18


. The slider


22


includes one or more data transducers


27


for reading and/or writing data on a magnetic medium such as a hard magnetic disk


30


. Similarly, the slider


26


includes one or more data transducers


28


for reading and/or writing data on a magnetic medium such as a hard magnetic disk


34


.





FIG. 2

is a cross-sectional view of the first transducer suspension


10


illustrating that the suspension


10


is a multilayered laminate


39


comprised of a first layer


40


, a second layer


44


and a third layer


48


. The first layer


40


is positioned adjacent to one surface of the second layer


44


. The third layer


48


is positioned adjacent to a different surface of the second layer


44


so that the second layer


44


separates the first layer


40


and the third layer


48


, with the layers


40


,


44


and


48


all lying in planes that are parallel to each other. The layers


40


,


44


and


48


are generally secured together by a thin adhesive layer applied between layers


40


and


44


and between layers


44


and


48


.




Representative dimensions and compositions for the various elements illustrated in

FIG. 2

are as follows: In the preferred embodiment, the first layer


40


has a thickness “w” of approximately 0.051 millimeters and comprises full hard 301, 302 or 304 stainless steel. In more general terms, the first layer


40


has a thickness “w” of approximately 0.076 millimeters, or less, and comprises a rigid material such as stainless steel. Typically, the first layer


40


comprises 300 series stainless steel, but other stainless steels and other rigid materials could also be used (e.g. beryllium copper or titanium).




In the preferred embodiment, the second layer


44


comprises a polyimide that has properties similar to the properties of Kapton® E brand polyimide manufactured by E.I. Du Pont de Nemours and Company (“Dupont”), including a dielectric constant in the range of approximately 3.0 to 3.5. Additionally, the coefficient of thermal expansion (CTE) of the polyimide should be such that the laminate


39


will be in a neutral stress condition after the laminate


39


is manufactured. A neutral stress condition means that the laminate


39


will remain flat after manufacturing and will not curl up after either the first layer


40


or the third layer


48


are etched. Furthermore, the adhesive used to secure the layers


40


,


44


and


48


together should be sufficiently robust to keep the laminate


39


intact up to a temperature of approximately 350° C.




In the preferred embodiment, the second layer


44


has a thickness “x” of approximately 0.0165 millimeters. This thickness is chosen because a thin layer


44


is needed to keep the stiffness of the suspension


10


low, but the price of polyimide films thinner than 0.0165 millimeters is a limiting consideration.




Rogers Corporation (Circuit Materials Unit), of Chandler, Ariz., supplies a laminate


39


having a second layer


44


that meets the specifications listed above. In ordering the laminate


39


, the desired material for the third layer


48


, such as one of the alloys described below, is provided to Rogers Corporation along with the specifications for the first layer


40


, the second layer


44


and the third layer


48


. Rogers Corporation then prepares a suitable laminate using proprietary methods.




In the Rogers laminate, the second layer


44


comprises a 0.0165 millimeter polyimide layer (layer


44


) which is thought to be the same polyimide (or a similar polyimide) as is used in the Kool Base® brand material manufactured by Mitsui Toatsu Chemicals, Inc. In the Kool Base polyimide, a thin layer of adhesive is applied to each side of the polyimide layer for bonding the layer


44


to the layers


40


and


48


.




A substitute for the Rogers laminate is a laminate custom manufactured by Dupont having a 0.0165 millimeter layer of Dupont's EKJ self-adhering polyimide composite (Kapton® E brand polyimide manufactured by Dupont) and meeting the other specifications listed above for the second layer


44


.




Stated more generally, the second layer


44


has a thickness “x” of approximately 0.018 millimeters or less, and comprises a dielectric material such as a polyimide having a dielectric constant in the range of approximately 3.0 to 3.5 and a coefficient of thermal expansion (CTE) which allows the laminate


39


to be in a neutral stress condition after the laminate


39


is manufactured.




Polyimides of the types described in U.S. Pat. Nos. 4,839,232, 4,543,295 and 5,298,331 are potentially useful as the second layer


44


, although the suitability of a specific polyimide for a particular purpose should be verified. Additionally, Teflon compounds of the formula F(CF


2


)


n


F are also suitable for use in the second layer


44


, as are nonconductive epoxies and other dielectric materials.




In the preferred embodiment, the third layer


48


has a thickness “y” of approximately 0.0178 millimeters and comprises a copper-nickel-silicon-magnesium alloy such as the copper alloy C7025 with a TMO3 temper (full hard heat temper) manufactured by Olin Brass (composition 96.2% Cu; 3% Ni; 0.65% Si; and 0.15% Mg).




Examples of other specific materials that can function as the third layer


48


include the following: 1. a high strength beryllium copper alloy (composition: 97.2-98.4% Cu; 0.2-0.6% Be; and 1.4-2.2% Ni, such as Brush Wellman beryllium copper alloy 3 (C17510) with an HT temper); 2. a high strength brass alloy (composition: 97.5% Cu; 2.35% Fe; 0.03% P;: and 0.12% Zn, such as Olin Brass copper alloy C194 with an ex. spring temper); 3. a high strength titanium copper alloy (composition: 96.1-96.6% Cu; and 2.9-3.4% Ti, such as Nippon Mining titanium copper alloy with a TiCuR1-EHM temper).




Stated more generally, the third layer


48


comprises a high strength electrically conducting material and has a thickness “y” of approximately 0.018 millimeters or less. For purposes of the present invention, the term “high strength” refers to a material with a tensile yield strength (Sy) greater than 70 ksi (kilopounds per square inch) and which doesn't soften by more than 10% when exposed to a temperature of 300° C. for one hour.





FIG. 3

is a top view of the first transducer suspension


10


. The suspension


10


has a slider portion


54


, an arm portion


58


and a link portion


62


(also referred to as a load beam). A plurality of electrical lines


66


are present on a surface


70


of the system


10


. Each electrical line


66


has a space


74


positioned along each of its sides so as to prevent the electrical line


66


from shorting out with an adjacent electrical line


66


.




A plurality of hinges


78


are also shown in the surface


70


. The hinges


78


are regions in which the third layer


48


has been removed to form channels in the third layer


48


. The hinges


78


increase the flexibility of the suspension


10


and/or permit the suspension


10


to be bent at some predetermined angle. Similarly, hinges can also be formed by etching channels in the first layer


40


.




The portions


54


,


58


and


62


designate regions of the suspension


10


, but the suspension


10


is preferably formed from one continuous piece of laminated material as is explained herein with respect to

FIGS. 2 and 4

.




The slider portion


54


is the part of the suspension


10


on which the read/write slider


22


is mounted. The electrical lines


66


form the electrical connections for connecting the slider


22


and the transducer


27


to an external system as is explained later with respect to FIG.


5


.




The arm portion


58


is the part of the suspension


10


that is connected to the actuator arm


18


. Typically, the arm portion


58


is attached to the actuator arm


18


by bonding, welding, swaging or screwing the arm portion


18


to the actuator arm along the first layer


40


shown in FIG.


2


.




The link portion


62


connects the arm portion


58


to the slider portion


54


. The suspension


14


is identical to the suspension


10


and includes all of the elements shown in

FIG. 3

, including the portions


54


,


58


and


62


and the electrical lines


66


.





FIG. 4

is a cross-sectional view of the suspension


10


illustrating that the electrical lines


66


are regions of the third layer


48


that are roughly rectangular in cross section, and that are separated from each adjacent electrical line


66


by one of the spaces


74


. The spaces


74


extend down to the second layer


44


so that the second layer


44


is exposed through the space


74


.




The electrical lines


66


are formed by etching the surface


70


using standard metal etching techniques. For example, when the third layer


48


comprises one of the copper alloys described above, the layer


48


is etched with ferric chloride or other suitable etchants. The etching process removes metal from specified regions, thereby forming the spaces


74


that define the electrical lines


66


. In practice, a typical chemical etching process will not form a groove having the perfect rectangular shape illustrated in

FIG. 4

for the spaces


74


. Actual grooves formed by a chemical etching process are slightly rounded or tapered as is well-known in the art. In general, features such as the electrical lines


66


, the spaces


74


and the hinges


78


are formed directly on the third layer


48


using photolithographic processes or by using numerically controlled imaging such as laser machining.




In the preferred embodiment, the first, second and third layers


40


,


44


and


48


initially comprise a continuous sheet of laminated material of stainless steel/polyimide/copper alloy laminate. A plurality of slider suspension systems


10


are then manufactured from the sheet of laminate using the techniques described above.




A general procedure for the preparation of the metal-polyimide laminated material is described by St. Clair et al. in U.S. Pat. No. 4,543,295 (issued Sep. 24, 1985).





FIG. 5

is a schematic diagram of a magnetic recording disk file


84


that utilizes the transducer suspension system


10


of the present invention. It should be appreciated that the suspension system


14


is identical to the suspension system


10


so that the following comments apply equally to either the suspension system


10


or the suspension system


14


. It should also be appreciated that the suspension systems


10


and


14


could be used with other data storage systems, such as floppy disk drives, optical drives or compact disk players.




The disk file


84


comprises a plurality of magnetic recording disks


88


suitable for use in hard disk drives. The disks


88


are mounted on a spindle shaft


92


which is connected to a spindle motor


96


. Motor


96


is mounted to a chassis


100


.




The plurality of read/write sliders


22


and


26


are positioned over the disks


88


such that each disk


88


can be accessed by one of the sliders


22


or


26


. Each of the sliders


22


and


26


includes a transducer for reading and writing data on a plurality of concentric data tracks on the disks


88


and are attached to one of the suspension systems


10


(or


14


). Each of the suspension systems


10


(or


14


) are attached to the actuator arm


18


which is attached to a rotary actuator


104


. The rotary actuator


104


moves the actuator arm


18


(and hence the suspension system


10


or


14


and the sliders


22


or


26


) in a radial direction across the disk


88


. An enclosure


108


(shown by a dashed line in

FIG. 5

) seals the disk file


84


and provides protection from particulate contamination.




A controller unit


112


provides overall control to the system


84


. The controller unit


112


contains a central processing unit (CPU), memory unit and other digital circuitry and is connected to an actuator control/drive unit


116


which in turn is electrically connected to the actuator


104


. This allows the controller


112


to control the movement of the sliders


22


and


26


over the disks


88


. The controller


112


is electrically connected to a read/write channel


120


which in turn is electrically connected to the sliders


22


and


26


. This allows the controller


112


to send and receive data from the disks


88


. The controller


112


is electrically connected to a spindle control/drive unit


124


which in turn is electrically connected to the spindle motor


96


. This allows the controller


112


to control the rotation of the disks


88


. A host system


128


, which is typically a computer system, is electrically connected to the controller unit


112


. The host system


128


may send digital data to the controller


112


to be stored on the disks


88


, or may request that digital data be read from the disks


88


and sent to the system


128


. The basic operation and structure of data storage systems, such as the disk file


84


(without the suspension systems


10


or


14


), is well-known in the art and is described in more detail in


Magnetic Recording Handbook


, C. Dennis Mee and Eric D. Daniel, McGraw-Hill Book Company (1990).





FIG. 6

is an isometric view of a head gimbal assembly


130


(HGA


130


) according to the prior art. The HGA


130


includes a load beam


134


and a pair of flexure arms


136


and


138


. The flexure arms


136


and


138


are joined at a slider portion


142


. A slider


146


is attached to the slider portion


142


. The slider


146


is a conventional magnetoresistive (MR) slider having an air bearing surface and a backside surface which is on the opposite side of the slider


146


from the air bearing surface. A plurality of read/write termination pads


150


are positioned on the backside of the slider


146


and a plurality of discrete wires


154


are connected to the termination pads


150


for electrically connecting a pair of head transducers (such as the transducers


27


and


28


shown in

FIG. 1

) to a read/write channel (such as the read/write channel


120


shown in FIG.


5


).




The slider


146


is positioned in a cavity


158


that is formed between the flexure arms


136


and


138


. The backside of the slider


146


is attached to the slider portion


142


and rests on a dimple


161


positioned on a support


162


which is an end of the load beam


134


that extends under the slider


146


. The flexure arms


136


and


138


are extensions of the load beam


134


which have less thickness than the load beam


134


. A more thorough description of the HGA


130


can be found in U.S. Pat. No. 5,331,489.





FIG. 7

is an isometric view of a head gimbal assembly


170


(HGA


170


) according to the present invention. The HGA


170


includes a load beam


174


and a pair of flexure arms


176


and


178


. The flexure arms


176


and


178


are joined at a slider portion


182


. The slider portion


182


includes a tab


184


. A slider


186


is attached to the tab


184


, typically by a layer of epoxy


188


positioned between the slider


186


and the tab


184


(see FIG.


10


). The slider


186


is a conventional magnetoresistive (MR) slider having an air bearing surface


190


and a backside surface


194


which is on the opposite side of the slider


186


from the air bearing surface


190


.




A plurality of read/write termination pads


198


are positioned on the backside surface


194


. A plurality of electrical lines


202


are connected to the termination pads


198


for electrically connecting a pair of head transducers (such as the transducers


27


and


28


shown in

FIG. 1

) to a read/write channel (such as the read/write channel


120


shown in FIG.


5


). Typically, the electrical lines


202


are connected to the termination pads


198


by ultrasonic bonding. A plurality of spaces


206


are positioned between the electrical lines


202


to prevent the electrical lines


202


from contacting each other.




The slider


186


is positioned in a cavity


210


that is formed between the flexure arms


176


and


178


. The backside surface


194


is attached to the slider portion


182


and rests on a dimpled area


213


formed on a support


214


(i.e. the dimpled area


213


is a raised area positioned between the backside surface


194


and the support


214


). The support


214


is an end of the load beam


174


. The flexure arms


176


and


178


are extensions of the load beam


174


which have less thickness than the load beam


174


. In the preferred embodiment, the load beam


174


is comprised of stainless steel and the flexures


176


and


178


are formed by chemically etching the stainless steel to reduce its thickness.





FIG. 8

is a cross-sectional view of the HGA


170


illustrating that where the electrical lines


202


overlap the load beam


174


, the HGA


170


is a multilayered structure comprised of a first layer


220


analogous to the first layer


40


, a second layer


224


analogous to the second layer


44


and a third layer


228


analogous to the third layer


48


. The dimensions and compositions of the layers


220


,


224


and


228


are identical to those previously described for the layers


40


,


44


and


48


with respect to FIG.


2


. However, in the HGA


170


, the layers


220


,


224


and


228


are oriented so that the third layer


228


is facing away from the side of the disk


88


over which the slider


186


is flying.





FIG. 8

also illustrates that the electrical lines


202


are regions of the third layer


228


that are roughly rectangular in cross section, and that are separated from each adjacent electrical line


202


by one of the spaces


206


. The spaces


206


extend down to the second layer


224


so that the second layer


224


is exposed through the space


206


. One of the spaces


206


is positioned along each side of an electrical line


202


so as to prevent the electrical line


202


from shorting with an adjacent electrical line


202


. The electrical lines


202


are formed in the same manner as was previously described for the electrical lines


66


.





FIG. 9

is a cross-sectional view illustrating that where the electrical lines


202


cross the slider


186


, the first layer


220


has been completely removed from underneath the second layer


224


leaving only the layers


224


and


228


. A space


232


separates the slider


186


from the second layer


224


, thereby allowing the slider


186


to gimbal (move) more or less unrestricted from the electrical lines


202


.





FIG. 10

is a cross-sectional view illustrating that the electrical lines


202


and the second layer


224


are positioned on a first side of the tab


184


. The tab


184


supports the electrical lines


202


and the second layer


224


and provides strain relief for the electrical lines


202


. The layer of epoxy


188


is positioned on a second side of the tab


184


for bonding the slider


186


to the tab


184


.




Each electrical line


202


is bonded to one of the termination pads


198


, preferably by ultrasonic bonding. The termination pads


198


are regions where a plurality of electrical leads


236


terminate on the backside surface


194


, with each electrical lead


236


terminating in one of the pads


198


. The electrical leads


236


provide electrical connection to the transducers on the slider


186


.




As can be seen in

FIG. 10

, the second layer


224


is positioned between the electrical leads


236


and the electrical lines


202


, thereby preventing the electrical lines


202


from shorting the leads


236


.




The construction and use of the HGA


170


is analogous to the construction and use of the suspension


10


shown in

FIG. 3

, and the HGA


170


can be substituted for the suspensions


10


or


14


in the disk file


84


shown in FIG.


5


. Specifically, the slider portion


182


is analogous to the slider portion


54


and the load beam


174


is analogous to the link portion


62


. In use, the load beam


174


includes an arm portion (not shown) analogous to the arm portion


58


. The slider


186


includes one or more data transducers for reading and/or writing data on a magnetic medium. However, with the HGA


170


, the electrical lines


202


extend along the side of the load beam


174


that faces away from the disk


88


(shown in

FIG. 5

) on which the slider


186


is reading or writing data.




The flexures


176


and


178


are regions of reduced stiffness (compared to the load beam


174


) that separate the slider portion


182


from the load beam


174


and which function to allow the slider


186


to conform to, and fly over, the recording disk


88


(shown in FIG.


5


).




In the preferred embodiment, the HGA


170


is manufactured from a laminated material such as the multilayered laminate


39


shown in FIG.


2


. Photolithography and chemical etching are then used to form the various features of the HGA


170


, such as the electrical lines


202


, the flexures


176


and


178


and the space


210


. This manufacturing process eliminates the need to add discrete twisted pair read/write cables to the HGA


170


by hand.





FIG. 11

is an alternative embodiment showing the electrical lines


202


attached to the electrical leads


236


by a soldering techniques similar to the techniques disclosed in U.S. Pat. Nos. 4,761,699 or 4,789,914. In this alternative embodiment, a solder ball


240


is added to each termination pad


198


. The second layer


224


is extended over the termination pads


198


and an aperture


244


is etched through the second layer


224


. A solder ball


248


on the electrical line


202


is then reflowed to the solder ball


240


through the aperture


244


using a laser or a hot tip to melt the solder. Preferably, the solder balls


240


and


248


comprise tin-lead (SnPb) or tin-bismuth ((SnBi) eutectic solder, but other types of solder can be used.




Referring now to

FIGS. 1 and 2

, the utility of the laminated structure


39


can be explained. The trend within the hard disk drive industry towards smaller drives has created a demand for very small (and low cost) head gimbal assemblies. The laminated structure of the transducer suspension


10


permits very small head gimbal assemblies to be designed especially when the third layer


48


is comprised of a high strength electrical conductor.




The three layers of the suspension


10


function as follows: The first layer


40


(or


162


) is a stiffener layer that gives rigidity to the system


10


. The second layer


44


(or


164


) is comprised of a dielectric material that functions as an electrical insulator between the first layer


40


(or


162


) and the third layer


48


(or


166


). For some applications, it is useful if the second layer


44


(or


164


) is a dielectric material that also has viscoelastic properties (like a polyimide) which increases damping. Viscoelastic means that the stress in a deformed material is proportional to both the deformation and the rate of deformation. Viscoelastic materials also exhibit creep and relaxation behavior. Creep means that under constant stress the deformation increases in time. Relaxation means that under constant fixed deformation the stress decreases steadily in time.




The third layer


48


(or


166


) is comprised of a high strength electrically conducting material, such as one of the high strength copper alloys described previously. The third layer


48


(or


166


) is preferably comprised of a high conductivity alloy (e.g. a copper alloy) because the electrical lines


66


(or


154


) need to function as efficient electrical conductors.




The use of high strength alloys in the third layer


48


(or


166


) is important for several reasons: First, the use of a high strength alloy in the conductor layer reduces the stiffness of the suspension


10


(or


130


) which is important when the slider


22


(or


152


) is small (See Example 2 below).




Second, the use of a high strength alloy permits the thickness of the third layer


48


(or


166


) to be kept less than or equal to eighteen microns (as shown in Example 1 below, thickness varies inversely with the square root of yield strength).




Third, the use of a high strength alloy permits more design options such as the integration of the electrical lines


66


(or


154


) and the hinges


78


directly into the third layer


48


(or


166


). Similarly, the use of a high strength alloy permits the use of the flexures


134


and


138


, because the third layer


166


carries most of the load once the first layer


162


has been removed.




Fourth, the high strength copper alloy adds robustness to the suspension and reduces yield losses due to handling damage during the manufacturing process.




EXAMPLE 1




The reason use of a high strength alloy reduces the thickness of the third layer


48


(or


166


) is illustrated by the following discussion:




The thickness “t” of a rectangular metal strip having a width “w” and a length “L” is related to the yield strength of the material “S


y


” by equation 1:








t=C/S




Y


  (1)






where C=constant=(6PL/w)


½


and P is the load applied to the metal strip to cause it to bend.




The following calculation uses Equation 1 to illustrate that if the metal strip must carry the same load (P) and is comprised of a second material having a yield strength which is three times greater than the yield strength of a first material, then the metal strip comprised of the second material can be 42% thinner and still have the same strength: If S


yl


=soft copper yield strength=30 ksi; and S


y2


=high strength copper alloy yield strength=90 ksi; then t


2


/t


1


=(S


y1


/S


y2


)


½


=0.58 (a 42% reduction in thickness).




EXAMPLE 2




The reason use of a high strength alloy reduces the stiffness of the third layer


48


(or


166


) is illustrated by the following discussion:




The stiffness “k” of a rectangular metal strip having a width “w” and length “L” is related to the thickness “t” of the material by equation 2:








k=Dt




3


  (2)






where D=constant=Ew/6L


3


and E is Young's modulus.




The following calculation uses Equation 2 and the result of Example 1 to illustrate that if the metal strip must carry the same load (P) and is comprised of a second material having a yield strength which is three times greater than a first material, then the metal strip comprised of the second material has an 81% reduction in stiffness: If S


y1


=soft copper yield strength=30 ksi; and S


y2


=high strength copper alloy yield strength=90 ksi; then k


2


/k


1


=(t


2


/t


1


)


3


=(0.58)


3


=0.19 (an 81% reduction in stiffness).





FIG. 12

illustrates a head gimbal assembly


260


(HGA


260


) of the type used in the prior art. The HGA


260


comprises a slider


264


, a load beam


268


, an arm portion


272


and a plurality of electrical wires


276


. The electrical wires


276


are discrete wires which are routed over the back of the slider


264


and are tacked in place with epoxy. The resulting epoxy “bump” takes up space in the vertical direction (called “z-height”) and limits how closely a pair of magnetic disks can be stacked adjacent to each other in the disk file.




A swage joint


280


connects the arm portion


272


to an actuator arm, such as the arm


18


illustrated in

FIG. 5. A

region


284


and a region


288


indicate portions of the load beam


268


which extend beyond the slider


264


, thereby taking up disk area at the ID track of the magnetic disk.





FIG. 13

illustrates a head gimbal assembly


292


(HGA


292


) according to the present invention. The HGA


292


comprises a load beam


296


, a flexure arm


300


, a flexure arm


304


, a slider portion


308


, a slider


312


and a plurality of electrical lines


316


. A plurality of spaces


320


are positioned adjacent to each side of the electrical lines


316


to prevent the electrical lines


316


from contacting each other or other electrically conductive material. The electrical lines


316


are positioned on a dielectric layer


322


that prevents the electrical lines from contacting other electrically conductive materials.




In the preferred embodiment, the load beam


296


is elongated, like the load beam


268


of the HGA


260


, and the HGA


292


includes an arm portion, like the arm portion


272


shown in

FIG. 12

, for connecting the load beam


296


to an actuator arm. The load beam


296


includes an end


326


.




The load beam


296


and flexure arm


304


are contoured to fit tightly against a disk spacer


324


such that the HGA


292


contacts the spacer ring


324


at a corner


328


of the slider


312


. The spacer ring


324


is the portion of the spindle hub


92


that separates the disks


88


in FIG.


5


. An arrow


330


indicates the direction of rotation of the spacer ring


324


(and the attached magnetic disk).




The slider portion


308


and flexure arm


304


are contoured so that the HGA


292


does not take up additional disk space at the disk ID track. This allows more data tracks on the disk to be utilized for storing data. Typically, the design of the HGA


292


allows side clearances between the slider corner


328


and the read/write-element as low as 0.45 mm to 0.80 mm., depending on the slider size and read/write element location.




The flexure arm


300


includes a beam portion


332


which is oriented approximately parallel to the longitudinal axis of the flexure arm


300


but rests in the same plane as the flexure arm


300


. Similarly, the flexure arm


304


includes a beam portion


336


which is oriented approximately parallel to the longitudinal axis of the flexure arm


304


but rests in the same plane as the flexure arm


304


. The length of the beam portions


332


and


336


can be sized to ensure that the slider


312


translates (without pitch and roll rotation) when the load


402


(shown in

FIG. 17

) is applied.




In the preferred embodiment, the beam portion


332


is a continuous part of the flexure arm


300


that is connected to the flexure arm


300


by a unshaped curve section


337


. Similarly, the beam portion


336


is a continuous part of the flexure arm


304


that is connected to the flexure arm


304


by a unshaped curve section


338


.




The slider portion


308


is an “I-shaped” member that includes a longitudinal section


340


and two cross members


341


and


342


. The beam portions


332


and


336


intersect the cross member


342


near an edge


343


of the cross member


342


. An opening


344


is formed in the region bounded by the end


326


, the flexure arms


300


and


304


, the beam portions


332


and


336


and the edge


343


.




The electrical lines


316


extend over the longitudinal section


340


, the cross member


342


and across the opening


344


. An “S-shaped” loop


348


is formed by some of the electrical lines


316


in the opening


344


near the end


326


. Similarly, a reverse “S-shaped” loop


352


is formed by some of the electrical lines


316


in the opening


344


near the end


326


. The purpose of the loops


348


and


352


is to create some “play” in the electrical lines


316


so as to minimize the contribution of the electrical lines


316


to the pitch and roll stiffness of the HGA


292


.





FIG. 14

is an isometric view of the HGA


292


illustrating that the edges of the load beam


296


are curved downwards (i.e. in the direction away from the electrical lines


316


) to form a stiffening flange


360


and a stiffening flange


364


. The downward curl of the flanges


360


and


364


means that they do not require additional z height.





FIG. 14

also illustrates that a pair of read termination pads


368


and a pair of write termination pads


372


are located on a trailing edge


376


of the slider


312


. One electrical line


316


is attached to each termination pad


368


and to each termination pad


372


, preferably by ultrasonic bonding. The slider


312


is a conventional magnetoresistive slider having an air bearing surface


380


, a leading edge


381


and a backside surface


385


positioned opposite to the airbearing surface


380


. The slider


312


also includes one or more data transducers for reading and/or writing data on a magnetic medium, and these are usually positioned on the trailing edge


376


.




The load beam


296


has a backside surface


387


that faces away from a disk


388


on which the slider


312


is reading and/or writing data.





FIG. 15

is a cross-sectional view of the HGA


292


illustrating that where the electrical lines


316


overlap the load beam


296


, the HGA


292


is a multilayered structure comprised of a first layer


390


analogous to the first layer


40


, a second layer


394


analogous to the second layer


44


and a third layer


398


analogous to the third layer


48


. The dimensions and compositions of the layers


390


,


394


and


398


are identical to those previously described for the layers


40


,


44


and


48


with respect to FIG.


2


. However, in the HGA


292


, the layers


390


,


394


and


398


are oriented so that the third layer


398


is facing away from the air bearing surface


380


. The second layer


394


is positioned between the slider support portion


308


and the third layer


398


.





FIG. 15

also illustrates that the electrical lines


316


are regions of the third layer


398


that are roughly rectangular in cross section, and that are separated from each adjacent electrical line


398


by one of the spaces


320


. The spaces


320


extend down to the second layer


394


so that the second layer


394


is exposed through the space


320


. One of the spaces


320


is positioned along each side of an electrical line


316


so as to prevent the electrical line


316


from shorting with an adjacent electrical line


316


. The electrical lines


316


are formed in the same manner as was previously described for the electrical lines


66


.





FIG. 16

is a cross-sectional view illustrating that where the electrical lines


316


cross the opening


344


, the first layer


390


has been completely removed from underneath the second layer


394


leaving only the layers


394


and


398


. The combination of the electrical lines


316


and the second layer


394


is referred to as an integrated electrical cable


399


.




In the preferred embodiment, the HGA


292


is manufactured from a laminated material such as the multilayered laminate


39


shown in FIG.


2


. Photolithography and chemical etching are then used to form the various features of the HGA


292


, such as the electrical lines


316


, the flexure arms


300


and


304


and the opening


344


.





FIG. 17

is a side view of the HGA


292


illustrating that the deflection “d” due to the load “L” takes place in the space “T” between the disk


388


(shown in

FIG. 14

) and a back surface


407


of the HGA


292


, and does not require additional z-height. Z-height is defined as height in the direction “z” illustrated by the coordinate system shown in FIG.


17


. The load “L” is a force applied in the direction indicated by the arrow


402


which arises from a preformed area near the arm attach area of the load beam


296


.




The design of the HGA


292


is chosen so that the total z-height of the HGA


292


is equal to thickness of the slider


312


plus the thickness of the load beam


296


and the layer of epoxy that bonds the slider


312


to the slider portion


308


, plus the thickness of the electrical cable


399


positioned on top of the slider portion


308


. In the preferred embodiment, the total z-height of the HGA


292


is less than or equal to 1.3. mm. The thickness of the electrical cable


399


is less than or equal to 0.035 mm. Typically, the design of the HGA


292


allows the disks


88


(shown in

FIG. 5

) to be spaced 1.0 mm to 1.3 mm apart, depending on the size of the slider


312


.





FIG. 17

also shows that a region


406


of the flexure arm


300


has a thickness which is less than the thickness of the load beam


296


. The flexure arm


304


has a similar thickness to the flexure arm


300


. The flexure arms


300


and


304


are regions of reduced stiffness (compared to the load beam


296


) that separate the slider portion


308


from the load beam


296


and which function to allow the slider


312


to conform to, and fly over, a magnetic disk (like the recording disk


88


shown in FIG.


5


). The flexure arms


300


and


304


are comprised entirely of the first layer


390


and form continuous extensions of the load beam


296


.





FIG. 18

illustrates a frame


410


used in manufacturing the HGA


292


. The frame


410


is formed as an extension of the HGA


292


when the laminated material, such as the multilayered laminate


39


shown in

FIG. 2

, is etched to yield the HGA


292


. The frame


410


abuts the slider portion


308


and the flexure arms


300


and


304


at the shear lines


422


. All of the elements of the HGA


292


shown in

FIGS. 13 and 14

are formed approximately simultaneously with the frame


410


, including the load beam


296


, the flexure arms


300


and


304


the slider portion


308


, the plurality of electrical lines


316


, the plurality of spaces


320


, the slider portion


308


and the beam portions


332


and


336


. The slider


312


is not part of the frame


410


, but is attached later as is explained below.




The frame


410


also includes an aperture


414


, a plurality of electrical line extensions


418


and a plurality of shear lines


422


. The slider


312


is positioned at a ninety degree angle to the frame


410


with the termination pads


368


and


372


positioned along a line


426


and underneath the electrical lines


316


.




An ultrasonic bonding head is then positioned above the termination pads


368


and


372


with the electrical lines


316


between the ultrasonic bonding head and the termination pads


368


and


372


, and the electrical lines


316


are ultrasonically bonded to the termination pads


368


and


372


. In the preferred embodiment, the electrical lines


316


are plated with gold before the bonding process takes place, in order to facilitate the ultrasonic bonding process.




After the electrical lines


316


are ultrasonically bonded to the termination pads


368


and


372


, the frame


410


is sheared away from the HGA


292


at the shear lines


422


. The HGA


292


is then rotated ninety degrees while holding the slider


312


fixed so that the slider


312


becomes positioned in a position


430


indicated by phantom lines in FIG.


18


. Alternatively, the slider


312


could be rotated into the position


430


while holding the HGA


292


fixed. When the HGA


292


is rotated, the extensions


418


break off at a plurality of break points


434


, thereby completely freeing the HGA


292


from the frame


410


. The slider


312


is then bonded to the slider portion


308


with epoxy to secure it to the HGA


292


.





FIG. 19

is an alternative embodiment of the present invention illustrating a head gimbal assembly


440


(HGA


440


). The HGA


440


comprises a load beam


444


, a flexure arm


448


, a flexure arm


452


, a slider portion


456


, a slider


460


and a plurality of electrical lines


464


. A plurality of spaces


468


are positioned adjacent to each side of the electrical lines


464


to prevent the electrical lines


464


from contacting each other or other electrically conductive material. The electrical lines


464


are positioned on a dielectric layer


472


that prevents the electrical lines from contacting other electrically conductive materials.




In the preferred embodiment, the load beam


444


is elongated, like the load beam


268


of the HGA


260


, and the HGA


440


includes an arm portion, like the arm portion


272


shown in

FIG. 12

, for connecting the load beam


444


to an actuator arm. The slider


460


is similar to the slider


312


and has an air bearing surface


476


and a backside surface


480


. The electrical lines


464


run across a space


484


and include a pair of s-shaped loops


488


and


492


(other shapes are possible). A stiffening flange


494


is positioned along each edge of the load beam


444


. The load beam


444


has a frontside surface


495


which faces in the same direction as the airbearing surface


476


. The dielectric layer


472


is positioned on the frontside surface


495


.




The shape and composition of the HGA


440


is similar to the shape and composition of the HGA


292


, except as follows: The slider


460


is mounted on the opposite side of the HGA


440


as compared to the HGA


292


, so that the airbearing surface


476


is on the same side of the HGA


440


as the electrical lines


464


. Additionally, in the HGA


440


, the slider


460


is rotated 180 degrees so that a plurality of termination pads


496


are positioned proximally to the solder bumps


500


on the electrical lines


464


.




Since the electrical lines


464


do not have to extend over the slider


460


, the electrical lines


464


can be attached to the termination pads


496


by a plurality of solder bumps


500


, for example by using the soldering technique disclosed in U.S. Pat. No. 4,761,699. Because of the orientation of the slider


460


, a magnetic disk


504


rotates in the direction of an arrow


508


, which is opposite to the rotation shown in

FIG. 13

by the arrow


330


.





FIG. 20

is a cross-sectional view of the HGA


440


illustrating that the dielectric layer


472


is positioned between the electrical lines


464


and the space


484


and slider portion


456


. The electrical lines


464


and the spaces


468


have the same shapes and compositions as was described previously for the electrical lines


316


and the spaces


320


shown in

FIGS. 15 and 16

.





FIG. 20

also illustrates that the slider


460


is bonded to the slider portion


456


(preferably with epoxy) and that the flange


494


is bent upward (in the direction of the air bearing surface


476


) to minimize z-height. The HGA


440


exhibits the same reduced z-height and side space clearance as was described previously with respect to the HGA


292


.




Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be interpreted as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above disclosure. Accordingly, it is intended that the appended claims be interpreted as covering all alterations and modifications as fall within the true spirit and scope of the invention.



Claims
  • 1. A method for forming a head gimbal assembly comprising the steps of:a. forming the head gimbal assembly and a frame from a continuous portion of a laminated material comprised of a first layer, a second layer comprised of a dielectric material, and a third layer comprised of an electrically conductive material, the head gimbal assembly including a plurality of electrical lines formed by the third layer, the frame being a part of the head gimbal assembly and including a plurality of electrical line extensions that are formed by the third layer and that abut the plurality of electrical lines; b. positioning a slider having a plurality of termination pads at an angle to the frame, with the plurality of termination pads being positioned adjacent to the plurality of electrical lines; c. bonding the plurality of termination pads on the slider to the plurality of electrical lines; d. partially separating the frame from the head gimbal assembly; and e. changing a relative position of the slider to the head gimbal assembly by an amount sufficient to separate the plurality of electrical lines from the plurality of electrical line extensions.
  • 2. The method of claim 1 wherein the third layer has a thickness less than or equal to eighteen microns.
  • 3. The method of claim 1 wherein the third layer comprises an electrically conductive material selected from the group consisting of Cu—Ni—Si—Mg alloy, Be—Cu—Ni alloy, Cu—Fe—Zn—P alloy and Cu—Ti alloy.
  • 4. The method of claim 1 wherein the second layer comprises a polyimide.
  • 5. The method of claim 1 wherein the first layer comprises stainless steel.
Parent Case Info

This is a divisional application of application Ser. No. 08/643,935, filed on May 7, 1996, now U.S. Pat. No. 6,282,064, which is a continuation of Ser. No. 08/365,123, filed on Dec. 27, 1994, now abandoned, which was a continuation-in-part of application Ser. No. 08/270,928, filed Jul. 5, 1994 now abandoned, which was continued as application Ser. No. 08/613,287 filed Mar. 11, 1996, now abandoned, which was continued as application Ser. No. 08/972,100 filed Nov. 17, 1997, now U.S. Pat. No. 5,955,176.

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Number Name Date Kind
4594221 Caron et al. Jun 1986 A
4700250 Kuriyama Oct 1987 A
4732733 Sakamoto et al. Mar 1988 A
4866836 Von Brandt et al. Sep 1989 A
4996623 Erpelding et al. Feb 1991 A
5026434 Picault et al. Jun 1991 A
5145553 Albrechta et al. Sep 1992 A
5331489 Johnson et al. Jul 1994 A
5334346 Kim et al. Aug 1994 A
5424030 Takahashi Jun 1995 A
5427848 Baer et al. Jun 1995 A
6282064 Palmer et al. Aug 2001 B1
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Number Date Country
0 599 669 Jun 1994 EP
60-246015 Dec 1985 JP
4-2196618 Oct 1992 JP
6-44530 Feb 1994 JP
6-150597 May 1994 JP
2001-34905 Feb 2001 JP
Non-Patent Literature Citations (5)
Entry
Anonymous disclosure, “Circuitized Suspension Flexture—“Foliage” for Disk Drives,” Published in Research Disclosure, No. 339, Kenneth Mason Publications Ltd, England (Jul. 1992).
Cooper et al., “Constrained Layer Damper Spring Assemblies,” IBM Technical Disclosure Bulletin, vol. 33, No. 8, pp. 373-374 (Jan. 1991).
Rogers Corporation, “FLEX-I-MID® Adhesiveless Laminate,” Product Data Sheet (not dated).
Mitsui Toatsu Chemicals, Inc. “KOOL BASE®,” Product Data Sheet, pp. 1-7 (not dated).
Ooyama et al., Magnetic Head Apparatus, English translation of Japanese Kokai, Document No. 5-182141, publication date Jul. 23, 1993, translated by Schreiber Translations, Inc. for United States Patent and Trademark Office, Washington, D.C., pp. 1-18 (Nov. 2000).
Continuations (3)
Number Date Country
Parent 08/365123 Dec 1994 US
Child 08/643935 US
Parent 08/613287 Mar 1996 US
Child 08/270928 US
Parent 08/972100 Nov 1997 US
Child 08/613287 US
Continuation in Parts (1)
Number Date Country
Parent 08/270928 Jul 1994 US
Child 08/365123 US