JP2004303358A - Laminated body for HDD suspension and HDD suspension - Google Patents

Abstract

[PROBLEMS] To provide an HDD suspension laminated body capable of reducing the weight of an HDD suspension and reducing vibration noise generated due to inertial force and subtle turbulence of airflow generated when moving and stopping repeatedly on a disk. I do.
A laminate comprising a stainless steel layer (A), a resin layer (B), and a stainless steel layer (C), wherein the thickness of each of the stainless steel layers (A) and (C) is in the range of 15 to 100 μm, and the resin layer (B) is a low thermal expansion polyimide. It is composed of a resin layer and a thermoplastic polyimide resin layer, has a coefficient of linear expansion of (1-3) × 10 ⁻⁵ / ° C., has a thickness of 8-150 μm, and has an adhesive force between the stainless steel layer A and the resin layer B. And a laminate for an HDD suspension in which the adhesion between the stainless steel layer C and the resin layer B is 0.5 kN / m or more.
[Selection diagram] None

Description

【００３８】
実施例１〜３で得た積層体及び比較例１のステンレス箔を用いてＨＤＤのロードビームに加工したが、加工の際に剥離や変形等の問題はいずれもなく、また、得られたロードビームをサスペンションに組み込んだＨＤＤについても、同様である。
【００３９】
【発明の効果】
本発明によれば、ＨＤＤの高容量化に対応した技術として、ＨＤＤサスペンションの構成部材であるステンレス製ロードビーム材をステンレス層／ポリイミド系樹脂層／ステンレス層の高機能性複合積層体にすることによって軽量化を図り、この技術によってディスク上で移動−停止を繰り返す際に生じる慣性力、及びサスペンションがディスク上を浮揚する際に生じる気流の微妙な乱れによって発生する振動ノイズを空気との摩擦によって低減することを可能にした。これによってディスクとスライダ間の距離を短縮して且つ安定的な浮揚姿勢を保つことが可能となり、これまで以上のトラック密度及び線記録密度を向上させることでＨＤＤの高容量化を可能にする。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laminated body suitable for an HDD (hard disk drive) suspension board and its use. More specifically, the present invention relates to a laminated body that enables a stainless steel load beam member, which is one of components of a suspension, to be reduced in weight.
[0002]
[Prior art]
The technological progress toward higher capacity of HDD is remarkable, and the surface recording density is improved by downsizing of the slider, and the average storage capacity per inch has already reached about 40 Gbits / in ² (IDEMA Japan News No. 47.p8-). 10). In these technologies, the replacement of the conventional wire-type suspension using wire lines to the wireless-type suspension with integrated wiring is progressing, and the establishment of this technology has led to the non-uniformity of the load on the wire lines, which was a conventional problem. The instability of the flying attitude of the slider due to the development of the slider is eliminated, and the technique of further reducing the size of the slider is made possible by the stabilization of the flying attitude, and the downsizing of the slider enables the track density and the linear recording (bit) density. This is because a technique for improving the write capacity has been achieved (Nikkei Electronics 1998.4.6. P167-177).
[0003]
However, the technical needs for increasing the capacity of HDDs do not seem to stop, and technology development for further increasing the capacity is progressing. Specifically, a method of improving the storage capacity by further reducing the size of the slider (Nikkei Electronics 1998.4.6. P167-177), or allowing the slider to move minutely by dividing the arm movement into multiple stages New technologies have been proposed, such as the introduction of a microactuator (IDEMA Japan News No. 45.p6-10) and a chip-on suspension (Nikkei Electronics 1998.4.6. P167-177) in which a chip amplifier is mounted directly on a suspension. ing. With the development of these new technologies, new technology needs include a technology for lowering and stabilizing the flying attitude of the slider and a technology for further improving the positional accuracy of the slider with respect to the disk.
[0004]
WO 98/08216 discloses a laminate composed of three layers of stainless steel foil / polyimide resin / copper foil used for a flexure blank member of a suspension or the like. Then, it is expected that the rigidity is reduced and the spring property is suppressed by reducing the thickness of each base material in the laminate. However, even if this method can reduce the flying distance of the slider, vibration noise generated by inertial force generated when the suspension moves on the disk and stops, and airflow generated by rotation of the disk cause the slider to move. Is affected by noise such as vibration noise due to wind turbulence that occurs when the surface floats.Therefore, there is a limit to the improvement of the surface memory density by reducing the thickness of the flexure blank material. It is necessary to take measures against these vibration noises.
[0005]
The suspension material of the HDD is composed of a combination of three types of components, a load beam material, a flexure blank material, and a mount material. The load beam material and the mount material are simply made of stainless steel. The load beam material serves as a support in the suspension member, and a relatively thick and rigid stainless steel material is used. Therefore, when the suspension operates while repeatedly moving and stopping on the disk, vibration is generated by the inertial force. Further, the slider flies due to the air current (wind turbulence) generated by the rotation of the disk. At this time, the turbulence also occurs at the same time, and the turbulence also generates vibration. When these vibration noises are generated, the vibrations reduce the positional accuracy of the slider, so that the areal recording density is reduced. If this vibration noise can be attenuated, it will be possible to achieve a higher surface memory density than ever, and furthermore, it will be possible to improve the data transfer speed by improving response speed delay and loss due to vibration noise. (IDEMA Japan News No. 50. p13-17).
[0006]
In order to solve such a problem, the stainless steel load beam member of the HDD suspension is half-etched to remove unnecessary portions in function and to reduce the weight so that the suspension may repeatedly move and stop on the disk. A method for reducing the generated inertial force, that is, a method for converting vibration into heat energy by viscousness due to air resistance to reduce vibration has been devised. However, it is difficult to process into a complicated shape by this method, and sufficient weight reduction cannot be achieved.
[0007]
[Patent Document 1]
WO98 / 08216 [Non-Patent Document 1]
Nikkei Electronics, 1998.4.6. p167-177
[Non-patent document 2]
IDEMA Japan News No. 47. p8-10
[Non-Patent Document 3]
IDEMA Japan News No. 45. p6-10
[Non-patent document 4]
IDEMA Japan News No. 50. p13-17
[0008]
[Problems to be solved by the invention]
The present invention achieves a further increase in the capacity of the HDD by reducing the weight of the stainless steel load beam member, which is a constituent member of the HDD suspension, by replacing a part of the stainless steel with a polyimide resin having a low specific gravity. An object of the present invention is to reduce vibration noise generated by inertial force generated when a suspension repeatedly moves and stops on a disk while operating, and vibration noise generated by wind turbulence when a slider floats on a rotating disk.
[0009]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve such problems, and as a result, it is possible to reduce the weight of the HDD suspension by further thermocompression bonding the stainless steel foil to a laminate obtained by applying a specific polyimide resin on the stainless steel foil. And completed the present invention.
[0010]
That is, the present invention is a laminate comprising a stainless steel layer A, a resin layer B, and a stainless steel layer C, wherein the thickness of each of the stainless steel layers A and C is in the range of 15 to 100 μm, and the thickness of the resin layer B is A laminate having a thickness of 8 to 150 μm and an adhesive force between the stainless steel layer A and the resin layer B and an adhesive force between the stainless steel layer C and the resin layer B of 0.5 kN / m or more. Body.
[0011]
Here, 1) the linear expansion coefficient of the resin layer B is 1 × 10 ^{−5 to} 3 × 10 ⁻⁵ / ° C., 2) the resin layer B is made of a polyimide resin, and 3) the resin layer B is a linear resin. 4) Resin having a multilayer structure having at least two layers of a low thermal expansion polyimide resin layer D having an expansion coefficient of 3 × 10 ⁻⁵ / ° C. or less and a thermoplastic polyimide resin layer E having a glass transition temperature of 300 ° C. or less. The layer B has a three-layer structure of a thermoplastic polyimide resin layer E1 / a low thermal expansion polyimide resin layer D / a thermoplastic polyimide resin layer E2, and the thermoplastic polyimide resin layer E1 and the thermoplastic polyimide resin layer E2 It may be the same or different, and the thickness of the low thermal expansion polyimide resin layer D occupies 50% or more of the entire resin layer B. 5) The thickness of the resin layer B is 20 to 20% of the total thickness of the laminate. 90% Or 6) the stainless steel layer A and C are SUS304 is a preferred embodiment of the present invention. It is also advantageous that the HDD suspension is for a load beam which is a component of the HDD suspension.
[0012]
According to the present invention, there is provided an HDD suspension, wherein a load beam of the HDD suspension is formed of the above-mentioned laminate for HDD suspension or obtained by processing the laminate.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The laminate for an HDD suspension of the present invention is used for at least one of the components of the HDD suspension, and includes the HDD suspension or the laminate (substrate) before being processed into the component. The suspension or a component of the suspension includes a processed laminate. As described in Patent Literature 1 and Non-Patent Literature 1, an HDD suspension is composed of a mount, a load beam, and a flexure (there is also one in which a load beam and a flexure are integrated). Suitable for load beams.
[0014]
The HDD suspension laminate of the present invention comprises a stainless steel layer A, a resin layer B and a stainless steel layer C. Preferably, the stainless steel layer is made of stainless steel foil and the resin layer is made of polyimide resin.
[0015]
The type of stainless steel forming the stainless steel layers A and C is not particularly limited, but SUS304 is preferable from the viewpoint of spring characteristics and dimensional stability, and SUS304 annealed at a temperature of 300 ° C. or more is particularly preferable. The thickness of the stainless steel layer is in the range of 15 to 100 μm, and more preferably in the range of 20 to 40 μm. Further, the total thickness of the stainless layers A and C is preferably in the range of 30 to 100 μm.
[0016]
If the thickness of the stainless steel layer is less than 15 μm, the rigidity required for the support is insufficient, while if it exceeds 100 μm, the weight of the support is heavy and the vibration damping effect is greatly reduced due to inertial force. The types and thicknesses of the stainless steels constituting the stainless steel layers A and C may be the same or different, but both are preferably in the above-mentioned preferred types or ranges.
[0017]
Various resins can be used as the resin constituting the resin layer B, but a polyimide resin is preferable from the viewpoint of dimensional stability and warpage. A general-purpose resin such as an epoxy resin is advantageous in terms of cost, but has a large thermal expansion coefficient, so that it is likely to be warped. When mounted on an HDD, the warpage does not provide positional accuracy and storage capacity is reduced. The resin layer B may be composed of a plurality of resin layers, or may be composed of a single resin layer. The thickness of the resin layer B is in the range of 8 to 150 μm. When the thickness is less than 8 μm, it is difficult to form a resin layer and hardly contributes to weight reduction. On the other hand, if it exceeds 150 μm, it will be too thick to maintain strength.
[0018]
The polyimide resin is polyimide or polyamide imide. What is necessary is just what has an imide bond in the structure, such as polyether imide. When the resin layer B is composed of a polyimide resin layer, it may be composed of only a single layer, but preferably composed of a plurality of polyimide resin layers. When the resin layer B is composed of a plurality of polyimide-based resin layers, it is preferable to use a polyimide-based resin layer in contact with the stainless steel layer that exhibits good adhesion to the stainless steel layers. Examples of the polyimide resin layer exhibiting good adhesiveness include a thermoplastic polyimide resin layer E having a glass transition temperature of 300 ° C. or less. In addition, the intermediate layer not in contact with the stainless steel layer has a low dimensional change rate with respect to temperature change, that is, a linear thermal expansion coefficient of 30 × 10 ⁻⁶ / ° C. or less from the viewpoint of dimensional stability when processed into an HDD suspension. A polyimide resin layer D is exemplified.
[0019]
Advantageously, the resin layer B is composed of three polyimide resin layers. In this case, the thermoplastic polyimide resin layer E1 / the low thermal expansion polyimide resin layer D / the thermoplastic polyimide resin layer E2 It is preferable to have a layer structure. Here, the thermoplastic polyimide-based resin layers E1 and E2 may be different in type and thickness or may be the same, but since both are layers in contact with the stainless steel layer, they exhibit good adhesion to the stainless steel layer. And a thermoplastic polyimide resin layer having a glass transition temperature of 300 ° C. or less. Similarly, the low thermal expansion polyimide resin layer D can also have a layer structure of two or more layers. Further, a thermoplastic polyimide resin layer E may be provided between the low thermal expansion polyimide resin layers D. The thickness of the low thermal expansion polyimide resin layer D occupying the total thickness of the resin layer B is preferably 50% or more, and more preferably 80 to 99%.
[0020]
The ratio of the total thickness of the stainless layers A and C to the thickness of the resin layer B is such that the thickness ratio of the stainless layer and the resin layer is in the range of 1: 0.05 to 4 times, but preferably in the range of 1: 0.1 to 4 The higher the ratio of the resin layer, the more effective the weight reduction. Advantageously, the thickness of the resin layer B is in the range of 5 to 90% of the thickness of the laminate, but is preferably 10 to 70%.
[0021]
Next, a method for producing a laminate of the present invention will be described.
In manufacturing the laminate, first, a polyimide resin liquid is applied on a stainless steel layer serving as a base. The polyimide resin can be applied by a known method, and is usually applied using an applicator. The polyimide-based resin solution may be a solution in which the imidized polyimide resin is dissolved in a solvent, but using a precursor solution of the polyimide-based resin, after application, after removing the solvent to some extent by preheating. The method of imidization by heat treatment is preferable. When an imidized polyimide resin solution is used, the heat treatment for imidization is naturally omitted. After the polyimide-based resin layer is formed in this manner, a stainless steel foil is stacked on the polyimide-based resin layer, and heated and pressed at a temperature of 280 ° C. or more, and is composed of a stainless steel layer / polyimide-based resin layer / stainless steel layer. It can be a laminate. The pressurizing condition is preferably in a range of 1 to 50 MPa and for 5 to 30 minutes. In addition, the hot pressing temperature during pressurization needs to be 280 ° C. or higher, but it is preferable to perform the pressing within a range of 300 to 400 ° C. If the thermocompression bonding condition is out of the above range, the laminate material is undesirably deformed such as warpage or a decrease in peel strength.
[0022]
Alternatively, two sheets each having a polyimide resin layer formed on stainless steel are stacked together with their resin surfaces aligned, and then heated and pressed at a temperature of 280 ° C. or more, and are composed of a stainless layer / polyimide resin layer / stainless layer. It can be a laminated body. As the stainless steel or polyimide resin used in this manufacturing method, the same ones as those used in the manufacturing method described first can be used, and the preferred embodiment is also the same, but for stainless steel, the thickness of both sides of the stainless steel layer Since different materials may have different amounts of deformation due to stress at the time of thermocompression bonding, it is preferable that the thickness of the stainless steel layer is the same from the viewpoint of stability of warpage of the laminated material. However, the thickness can be changed as necessary, and the thickness is not limited as long as the required amount of warpage is satisfied. In the case of this alternative method, the resin layer B formed on the stainless steel layer is constituted by a thermoplastic polyimide resin layer E / a low thermal expansion polyimide resin layer D / a thermoplastic polyimide resin layer E. The surfaces may be overlapped and thermocompression-bonded to form a laminate having a layer structure of stainless steel / E / D / E / E / D / E / stainless steel.
[0023]
In the laminate of the present invention, the adhesive force on the adhesive surface between the stainless steel layer A or C and the resin layer B is 0.5 kN / m or more. When the thickness is 0.5 kN / m or more, it is possible to prevent peeling during processing of the laminated body, deformation after forming a processed suspension, and the like. For example, when processing into a load beam material, it is necessary to have an adhesive strength that can withstand bending during processing and compression between rolls during transport, and repetitive inertial force generated when the suspension moves on the disk. is there. It has been found that when the peel strength is at least 0.5 kN / m, preferably at least 0.54 kN / m, more preferably at least 0.6 kN / m, it can be used favorably. The bonding surface structure of the stainless steel layer / resin layer having such an adhesive force is known from Patent Document 1 and the like, and can be achieved by selecting the type of the resin layer, the surface state of stainless steel, and the bonding conditions. In particular, this can be achieved by using a thermoplastic polyimide resin layer E as the resin to be the adhesive surface layer of the resin layer B. Here, the adhesive strength refers to a value measured by a peel strength test shown in Examples.
[0024]
When the laminate of the present invention is used for a load beam or the like, which is a support for a suspension, when warpage occurs, the positional accuracy for reading a magnetic signal is deteriorated, and the storage density per unit area is reduced. For this reason, it has been found that the warp is preferably 3 mm or less for a 65 mm disk. In the laminate of the present invention, the thermal expansion coefficient of the resin layer is preferably the same as that of the metal layer in order to prevent warpage, and the thermal expansion coefficient at 100 ° C. to 50 ° C. is 16 to 20 ppm / K. More preferably, there is.
[0025]
【Example】
Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples. The evaluation method of the basic characteristics in the examples is based on the following method, and the basic performance required for the load beam application is also described below. The polyimide resin used was one whose imidization was sufficiently completed.
[0026]
(Peel strength test)
The adhesive force between the metal layer and the resin layer is determined by forming a polyimide resin on a stainless steel foil, then thermocompression bonding the stainless steel foil to create a double-sided metal foil laminate, and processing it by 1/8 inch wiring. A width measurement specimen was prepared. This sample was stuck on a fixing plate, and the stainless steel layers on the application side and the crimping side were peeled in a 90 ° direction using a tensile tester (Strograph-M1 manufactured by Toyo Seiki Co., Ltd.) to measure the strength.
[0027]
(Measurement of warpage)
The warpage of the laminate was measured by forming a disk having a diameter of 65 mm by circuit processing and using a caliper to measure the portion where the warp was greatest when placed on a desk.
[0028]
(Measurement of linear thermal expansion coefficient)
The linear thermal expansion coefficient was measured by using a thermomechanical analyzer (manufactured by Senko Instruments) at a rate of 20 ° C./min to 255 ° C., holding at that temperature for 10 minutes, and further maintaining a constant 5 ° C./min. Cooled at speed. The average thermal expansion coefficient (linear thermal expansion coefficient) from 100 ° C. to 50 ° C. during cooling was calculated.
[0029]
(Measurement of test piece weight)
For the weight measurement, a test piece of 100 × 100 mm was prepared, and the weight of each substrate was measured using an electronic balance (EK-A) manufactured by A & D.
[0030]
Abbreviations used in Examples and the like are as follows.
BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride DADMB: 4,4′-diamino-2,2′-dimethylbiphenyl BAPP: 2,2′-bis [4- (4-amino [Phenoxy) phenyl] propane DMAc: N, N-dimethylacetamide
Synthesis Example 1
In order to synthesize a low thermal expansion polyimide resin having a linear expansion coefficient of 30 × 10 ⁻⁶ / ° C. or less, 9.0 mol of DADMB is weighed, and 25.5 kg of DADMB is stirred in a 40 L planetary mixer. It was dissolved in the solvent DMAc. Next, 8.9 mol of BPDA was added, and the polymerization reaction was carried out with stirring at room temperature for 3 hours to obtain a viscous polyimide precursor A solution.
[0032]
Synthesis Example 2
In order to synthesize a polyimide resin having a glass transition temperature of 300 ° C. or lower, 6.3 mol of BAPP was weighed and dissolved in 25.5 kg of a solvent DMAc while stirring in a 40 L planetary mixer. Next, 6.4 mol of BPDA was added, and the polymerization reaction was carried out with stirring at room temperature for 3 hours to obtain a viscous polyimide precursor B solution.
[0033]
Example 1
The solution of the polyimide precursor B obtained in Synthesis Example 2 was applied on a stainless steel foil (SUS304, manufactured by Nippon Steel Corporation, tension-annealed product, thickness 30 μm) so that the thickness after curing became 1 μm. After drying at 110 ° C. for 3 minutes, the solution of the polyimide precursor A obtained in Synthesis Example 1 was applied thereon so that the thickness after curing became 38 μm, and dried at 110 ° C. for 10 minutes. The solution of the polyimide precursor B obtained in Synthesis Example 2 was applied thereon so that the thickness after curing became 1 μm, dried at 110 ° C. for 3 minutes, and further stepwise in the range of 130 to 360 ° C. The imidization was inertized by heat treatment to obtain a 40 μm-thick laminate of a polyimide resin layer on stainless steel. Note that the first polyimide resin layer and the third polyimide resin layer were the same.
Next, a stainless steel foil (SUS304, manufactured by Nippon Steel Corporation, tension-annealed product, thickness 30 μm) is superimposed on the laminate, and a surface pressure of 15 MPa, a temperature of 320 ° C., and press pressure are applied using a vacuum press. Heat and pressure bonding was performed for 20 minutes to obtain a laminate of stainless steel layer / polyimide resin layer / stainless steel layer = 30/40/30. Table 1 shows the results of evaluating the characteristics of the laminate.
[0034]
Example 2
The solution of the polyimide precursor B obtained in Synthesis Example 2 was applied on a stainless steel foil (SUS304, manufactured by Nippon Steel Corporation, tension-annealed product, thickness 30 μm) so that the thickness after curing became 1 μm. After drying at 110 ° C. for 3 minutes, the solution of the polyimide precursor A obtained in Synthesis Example 1 was applied thereon so that the thickness after curing became 18 μm, and dried at 110 ° C. for 10 minutes. The solution of the polyimide precursor B obtained in Synthesis Example 2 was applied thereon so that the thickness after curing became 1 μm, dried at 110 ° C. for 3 minutes, and further stepwise in the range of 130 to 360 ° C. By imidation of imidization by heat treatment, a 20 μm thick first laminate of a polyimide resin layer was obtained on stainless steel. Note that the first polyimide resin layer and the third polyimide resin layer were the same.
Next, the two first laminates thus obtained are laminated so that the polyimide surfaces face each other, and using a vacuum press machine, the surface thickness is 15 MPa, the temperature is 320 ° C., and the press pressing time is 20 minutes. Under the conditions, the laminate was heated and pressed to obtain a laminate of stainless steel layer / polyimide resin layer / stainless steel layer = 30/40/30.
[0035]
Example 3
The solution of the polyimide precursor B obtained in Synthesis Example 2 was applied onto a stainless steel foil (SUS304, manufactured by Nippon Steel Corporation, tension-annealed product, thickness 25 μm) so that the thickness after curing became 1 μm. After drying at 110 ° C. for 3 minutes, the solution of the polyimide precursor A obtained in Synthesis Example 1 was applied thereon so that the thickness after curing became 8 μm, and dried at 110 ° C. for 10 minutes. The solution of the polyimide precursor B obtained in Synthesis Example 2 was applied thereon so that the thickness after curing became 1 μm, dried at 110 ° C. for 3 minutes, and further stepwise in the range of 130 to 360 ° C. By imidation of imidization by heat treatment, a first laminate having a thickness of 10 μm of a polyimide resin layer was obtained on stainless steel. Note that the first polyimide resin layer and the third polyimide resin layer were the same.
Next, a stainless steel foil (SUS304, manufactured by Nippon Steel Corporation, tension-annealed product, thickness 64 μm) is superimposed on the resin surface of the first laminate, and the surface thickness is 15 MPa and the temperature is set using a vacuum press. The laminate was heat-pressed at 320 ° C. under a press pressure time of 20 minutes to obtain a laminate of stainless steel layer / polyimide resin layer / stainless steel layer = 64/10/25.
[0036]
Comparative Example 1
A 100 μm stainless steel foil (SUS304, manufactured by Nippon Steel Corporation, tension-annealed product) was prepared and subjected to the same comparative evaluation.
[0037]
[Table 1]

[0038]
The laminates obtained in Examples 1 to 3 and the stainless steel foil of Comparative Example 1 were processed into a load beam of an HDD. The same applies to the HDD in which the beam is incorporated in the suspension.
[0039]
【The invention's effect】
According to the present invention, as a technology corresponding to an increase in capacity of an HDD, a stainless steel load beam material, which is a constituent member of an HDD suspension, is formed into a high-performance composite laminate of a stainless layer / polyimide resin layer / stainless layer. By this technology, the vibration noise generated by the inertial force generated when moving and stopping repeatedly on the disk and the subtle turbulence of the airflow generated when the suspension flies above the disk by this technology is caused by friction with air. It was possible to reduce. As a result, the distance between the disk and the slider can be reduced and a stable flying attitude can be maintained. By increasing the track density and the linear recording density more than before, it is possible to increase the capacity of the HDD.

Claims (9)

A laminate comprising a stainless steel layer A, a resin layer B, and a stainless steel layer C, wherein the thickness of each of the stainless steel layers A and C is in the range of 15 to 100 μm, and the thickness of the resin layer B is 8 to 150 μm. A laminate for an HDD suspension, wherein the adhesive strength between the stainless steel layer A and the resin layer B and the adhesive strength between the stainless steel layer C and the resin layer B are all 0.5 kN / m or more. 2. The HDD suspension laminate according to claim 1, wherein the resin layer B has a coefficient of linear expansion of (1-3) × 10 ⁻⁵ / ° C. 3. 3. The HDD suspension laminate according to claim 1, wherein the resin layer B is made of a polyimide resin. The resin layer B has a multilayer structure having at least two layers of a low thermal expansion polyimide resin layer D having a coefficient of linear expansion of 3 × 10 ⁻⁵ / ° C. or less and a thermoplastic polyimide resin layer E having a glass transition temperature of 300 ° C. or less. The laminate for an HDD suspension according to any one of claims 1 to 3, wherein: The resin layer B has a three-layer structure of a thermoplastic polyimide resin layer E1 / a low thermal expansion polyimide resin layer D / a thermoplastic polyimide resin layer E2, and a thermoplastic polyimide resin layer E1 and a thermoplastic polyimide resin layer. The HDD suspension laminate according to claim 4, wherein E2 may be the same or different, and the thickness of the low thermal expansion polyimide resin layer D occupies 50% or more of the entire resin layer B. The HDD suspension laminate according to any one of claims 1 to 5, wherein the thickness of the resin layer B is 5 to 90% of the total thickness of the laminate. 7. The HDD suspension laminate according to claim 1, wherein the stainless steel layers A and C are SUS304. The HDD suspension laminate according to any one of claims 1 to 7, wherein the HDD suspension is for a load beam of the HDD suspension. 8. An HDD suspension, wherein a load beam of the HDD suspension is formed from the HDD suspension laminate according to claim 1.