KR20010039598A - Damper and head suspension having the same - Google Patents

Abstract

PURPOSE: A damper is provided to prevent static electrification of a restriction body layer and to avoid damage of a head by carrying out antistatic treatment of a surface of the restriction body layer. CONSTITUTION: A restriction body layer(5) consisting of a plastic film and a viscoelastic body layer(6) consisting of an adhesive agent are laminated and integrated to form a damping material(4), which is further provided with an antistatic layer(7) formed by antistatic treatment on a surface of the restriction body layer(5). A separator(8) is temporarily laminated on an outer surface of the viscoelastic body layer(6) for the purpose of storage of the damping material(4) before it is stuck to a head suspension, easy handling at the time of carriage or the like and preventing tacky adhesion of the viscoelastic body layer(6), and the separator(8) is peeled when the damping material(4) is stuck to the head suspension. Therefore, forming the antistatic layer(7) at a face where the restriction body layer(5) comes in contact with the viscoelastic body layers(6) enables to more effectively prevent static electricity generated at the time of peeling the damping material(4) from the separator(8), i.e., pealing charge, and also prevents the antistatic layer(7) from being influenced by the exterior such as damage by contact or oxidation.

Description

Damper and head suspension using the same {DAMPER AND HEAD SUSPENSION HAVING THE SAME}

The present invention relates to a damper attached to a head suspension of a recording disk drive, and a head suspension using the damper.

This application is based on Japanese Patent Application Nos. 1999-133304 and 2000-65542, which are incorporated herein by reference.

A recording disk drive for rotating a recording disk such as a hard disk drive and a magneto-optical disk drive has a head portion for reading and writing information. As shown in FIG. 3A, the head portion is usually composed of a head 1 (for example, a magnetic head or an optical head) and a suspension 2 supporting the head 1. Reference numeral 3 is a block on which the head suspension is fixed.

The head portion immediately receives the air pressure from the rotating disk and the vibration transmitted by driving the head 1 or the motor to rotate the disk. Due to this, the head suspension formed by the spring-set or the like is deformed to shift the position of the head 1, causing errors in reading and writing.

In order to reduce the vibration of the head suspension 2, Japanese Patent Application Laid-Open No. 1992-8868 discloses a damper 4 composed of a laminate of a constraint layer and a viscoelastic layer on the head suspension 2, as shown in FIG. 3B. It is proposed to attach. According to this proposal, the viscoelastic layer compressed between the vibrating head suspension 2 and the constraint layer is deformed in accordance with the vibration of the head suspension 2 to generate internal resistance (molecular friction). As a result, the vibration energy is converted into thermal energy, and the vibration energy directly transmitted to the head suspension 2 is greatly reduced.

In order to ensure this vibration reduction effect, it is important to make the restraint layer have a high rigidity. Typically, the constraint layer used comprises a metal plate, such as stainless steel. Usually, the viscoelastic layer is made of pressure-sensitive adhesive, rubber or the like.

The damper in which the constraint layer is made of metal is excellent in damping effect, but it is difficult to give the head suspension 2 a spring-like characteristic because of its high rigidity. Furthermore, when dampers of a predefined size are blanked into a laminate with a metal sheet according to the shape of the head suspension 2, burrs are formed at the edges of the blank pieces which are inherently involved in the blanking operation of the metal sheet. It is difficult to perform precise blanking because the edges are deformed. In addition, there is a problem in that it is difficult to manufacture a lightweight damper using metal to manufacture the restraint layer and the material cost is high.

In order to solve these problems, it has been proposed to use a plastic film as a restraint layer that provides a cutting piece without blanking by blanking with high precision without impeding the provision of the spring characteristic of the head suspension 2.

However, plastic film as an insulator has caused a problem of charging, another problem that has not been experienced in the metal restraint layer. If a plastic film without antistatic treatment is used as the restraint layer, it is electrostatically charged, for example, when the damper peels off the release sheet. Dampers with this electrostatically charged plastic film are very easy to damage the head 1.

One conceivable solution to this problem is to knead conductive films, such as carbon, metal or metal oxides, into the plastic film to make the film conductive or semiconducting. However, there is a possibility that the conductive filler will fall off from the cutting edge when blanking the plastic film. If the damper with the conductive filler attached to the damper detached is attached to the head suspension 2, the fallen conductive filler will damage the head 1.

It is therefore an object of the present invention to provide a damper for a head suspension that does not interfere with the spring properties of the head suspension, has good blanking properties, reduces manufacturing cost and weight, and does not cause damage to the head.

Another object of the present invention is to provide a head suspension having such a damper.

A first embodiment of the present invention is a damper attached to a head suspension of a recording disk drive, comprising: a constraint layer and a viscoelastatic layer stacked on the constraint layer. ), Wherein the restraint layer comprises a plastic film, and at least one surface of the plastic film provides a damper subjected to an antistatic treatment.

Further, the second embodiment of the present invention provides a head suspension for a head of a recording disk drive, wherein the head suspension having the above-described damper is attached to at least a portion of the head suspension.

Applicants have done a lot of research for this purpose. In the course of this study, the Applicant provides a damper that, using the plastic film as the restraint layer, exhibits excellent workability of blanking without disturbing the spring properties of the head suspension, and can also suppress the manufacturing cost of the damper and reduce the weight. I found it very effective. Thus, the applicant has found that the drawbacks of using a plastic film do not damage the head by removing it by applying a specific antistatic treatment to the plastic film. As a result of various investigations, the applicant has found that the above-mentioned problem is solved by a damper which has applied an antistatic treatment to at least one of the surfaces of the plastic restrainer layer of the damper. The present invention is based on this solution. As used herein, the term "surfaces" for the constraint layer refers to both front and back.

Since the damping of the damper according to the present invention is achieved not by kneading conductive fillers such as carbon, metal or metal oxide in the plastic film, but by antistatic surface treatment of the plastic restraint layer, the internal conductivity during blanking The above-mentioned problem due to the fall of the filler does not occur.

In a preferred embodiment, the antistatic surface treatment is applied to the back side of the constraint layer, i.e. the surface which comes into contact with the viscoelastic layer. In this case, a high antistatic effect is produced against frictional charging when the damper is removed from the release sheet, and the antistatic layer can be protected from external influences such as scratching or oxidation.

In another preferred embodiment, the antistatic treatment is carried out by forming an antistatic layer by metal deposition or by coating with a conductive resin. The restraint layer having an antistatic layer formed by metal deposition has a very low surface resistance. The conductive resin coating film can be formed relatively easily, is transparent or translucent, and there is little change in color tone.

In another embodiment of the present invention, the plastic film is a polyimide film having an elastic modulus of 4.9 × 10 ⁹ / m 2 or more, which is relatively inexpensive and has good damping performance.

The head suspension having the above-mentioned damper on at least one part has the above-described effect provided by the damper, and effectively prevents reading and writing errors of the head.

The features and advantages of the invention can be understood from the detailed description of the disclosed preferred embodiments taken in conjunction with the accompanying drawings.

1 is a cross-sectional view of one embodiment of a damper according to the present invention;

2 is a cross-sectional view of another embodiment of a damper according to the present invention;

3a shows a head suspension,

3B is a diagram of a head suspension showing that the damper of the present invention is attached to the head suspension.

<Explanation of symbols for main parts of drawing>

4, 4 ': damper 5: restraint layer

6: viscoelastic layer 7: antistatic layer

8: release sheet

The damper of this invention contains the plastic film which is a restraint layer, and the single laminated body of a viscoelastic body layer comprised from a pressure sensitive adhesive. At least one of the surfaces of the restraint layer is subjected to an antistatic treatment, that is, the restraint layer has an antistatic layer on the at least one surface.

Preferred embodiments of the damper according to the present invention will be described with reference to the accompanying drawings. 1 is a sectional view of a damper 4 formed on the surface of the restraint layer 5 in which the antistatic layer 7 is in contact with the viscoelastic layer 6. Since the viscoelastic layer 6, which is an adhesive, is inconvenient to store or transport, it is protected by a release sheet that peels off the viscoelastic layer 6 in use so that the damper can be laminated to the head suspension of the recording disk drive. When the antistatic layer 7 is provided on the side of the restrainer layer 5 in contact with the viscoelastic layer 6 as shown in Fig. 1, frictional charging at the time of removing the damper from the release sheet can be effectively prevented. The antistatic layer 7 can be protected from external influences such as scratches or oxidation.

2 shows another embodiment of a damper. The damper 4 'shown has an antistatic layer 7 formed on the face, i.e., on the outer surface of the restraint layer, but its structure and use are the same as in the embodiment shown in FIG. Identical components have the same reference numerals. The damper 4 'does not interfere with the spring characteristics of the head suspension, is not electrostatically charged, is excellent in workability in blanking, can reduce manufacturing cost and weight, and does not damage the head.

The damper of the present invention is not structurally limited to the embodiment shown in FIGS. 1 and 2 in which the antistatic layer 7 is formed on one side of the restraint layer 5. For example, an antistatic layer 7 may be formed on both sides of the restraint layer 5, or a plurality of restraint layers 5 and a plurality of antistatic layers 7 are formed alternately to form a viscoelastic layer 6. It is possible to form a multilayer structure on one side of the.

The antistatic treatment, i.e., forming the antistatic layer 7 can be carried out by depositing a metal such as aluminum or chromium or by coating with an electrically conductive resin such as polyaniline or polypyrrole. Deposition of metals is particularly preferred as it has the effect of controlling surface resistance. In consideration of economics, aluminum deposition is preferred. Coating with a conductive resin is preferred in the antistatic layer because it can be formed relatively easily. In particular, polypyrrole is particularly preferable as the conductive resin in order to adjust the surface resistance.

The thickness of the antistatic layer 7 is not particularly limited and may be appropriately determined so that the surface resistance, charge amount, and half-life of the final damper can be achieved at a desired reference value. Typically, the thickness of the antistatic layer formed by metal deposition is about 100 kPa to 5000 kPa, and the thickness of the antistatic layer formed of conductive resin is about 0.01 µm to 5 µm. Methods of measuring surface resistance, charge amount and half-life, and their reference values are described in the examples below.

Although not limiting, the thickness of the plastic restraint layer 5 is preferably 5 µm to 200 µm. If the thickness is smaller than 5 mu m, the function of the constraint layer tends to be insufficient. If the thickness is larger than 200 mu m, the restraint layer tends to interfere with the characteristics of the head suspension as a spring.

The plastic film as the restraint layer 5 is not particularly limited, but a resin having a higher elastic modulus shows better vibration damping characteristics. From this point of view, it is preferable to use a resin having an elastic modulus of 2.9 × 10 ⁹ N / m 2. Useful plastic films include polyimide resin films, biaxially stretched polyethylene terephthalate (PET) films, biaxially stretched polypropylene films and aramid resin films. Of these, polyimide films having an elastic modulus of 4.9 × 10 ⁹ N / m 2 or more are good because of their good damping properties and relatively low cost.

Although the material of the viscoelastic body 6 is not specifically limited, It is preferable to use the acryl-type pressure sensitive adhesive which is generally excellent in a vibration damping characteristic and heat resistance. Since the internal temperature of the hard disk drive sometimes reaches 50 ° C. to 60 ° C., it is not preferable to use a material such as a butyl-based adhesive having insufficient heat resistance and susceptible to thermal deformation or thermal degradation. Although a silicone adhesive is known as a heat-resistant pressure sensitive adhesive, it is necessary to take into account the possibility of contaminating a recording layer of a hard disk or the like, causing a read or write error or damaging the head.

Acrylic pressure sensitive adhesives that can be used in the present invention are those prepared by a method for producing adhesives in the form of tapes disclosed in Japanese Patent Application Laid-Open No. 1993-132658, which include alkyl acrylate monomers, carboxyl-containing monomers, photopolymerization initiators and crosslinking. Ultraviolet polymers of monomer mixtures composed of binders. The alkyl acrylate monomer which can be used normally has 8 to 12 carbon atoms in the alkyl group.

Not only the silicone adhesive described above but also a material capable of generating organic gas contaminates the recording layer such as a hard disk. Therefore, in order to avoid generation of organic gas, it is necessary to reduce the organic gas from the viscoelastic material layer 6 having such a possibility. For example, this can be done by passing the adhesive layer applied to the restraint layer 5 and curing through a hot drying tower to evaporate the solvent and all unreacted components. In addition, the damper produced by blanking is vacuum dried to reduce organic gases such as solvent.

Although not restrictive, the thickness of the viscoelastic layer 6 is formed in a suitable range of 10 micrometers-250 micrometers. When thickness is made smaller than 10 micrometers, there exists a tendency for the damping effect to be inadequate. When thickness exceeds 250 micrometers, there exists a tendency for the characteristic as a spring of a head suspension to interfere.

The structure of the viscoelastic layer 6 is not limited to a single layer as shown in FIGS. 1 and 2, but may be a laminate composed of a plurality of viscoelastic films. In the case where the viscoelastic layer 6 has insufficient adhesive force to the head suspension, a separate adhesive layer may be provided on the viscoelastic layer 6.

The surface of the release sheet 8 comes into contact with the viscoelastic layer 6 treated with the release agent. For the same reasons as described above, it is preferable to use non-silicone release treatment agents such as long chain alkyl tape release treatment agents and fluorinated alkyl tape release treatment agents.

The damper of the present invention is manufactured as in the following examples. The restraint layer 5 and the viscoelastic layer 6 having an antistatic layer formed on at least one surface by an antistatic surface treatment are positioned to face each other, and are joined by suitable means to form a laminate. For example, the two members are press bonded through a pair of rubber rollers or bonded by a press. Further, the laminate can be produced by applying the pressure-sensitive adhesive forming the viscoelastic layer 6 directly to the restraint layer 5 and drying to form the viscoelastic layer 6.

Separately, a substrate such as a PET film is coated with the diluent solution of the non-silicone release treatment agent described above by a conventional method and dried in an oven or the like to produce a release sheet 8 having release characteristics. The release sheet 8 is applied to the viscoelastic layer 6 in a known method for producing the damper of the present invention. In use, the release sheet 8 peels off the viscoelastic layer 6.

The damper according to the present invention has the same vibration damping characteristics as having a metal restraint layer. In addition, it is competitive due to the light, inexpensive materials and hardly burrs are generated during fine blanking. When the antistatic treatment is performed that does not damage the head of the recording disk drive, the damper of the present invention is free from the problem of charging involving plastic material.

The dampers 4, 4 ′ of the present invention from which the release sheet 8 has been removed are laminated to the central portion of the head suspension 2 using the self-adhesion of the viscoelastic layer 6 as shown in FIG. 3b. Therefore, it is possible to manufacture a head suspension having excellent characteristics which effectively prevents errors in the head 1 during recording and reading. The dampers can be stacked not only in the central part but also in other parts (both transverse and opposite sides) or in all parts on the head suspension. Preferably, the dampers can be laminated on the viscoelastic layer 6 by means of a separately applied adhesive as described above. The adhesive used may be appropriately selected from a variety of known adhesives depending on the material of the head suspension 2.

The present invention is now described in more detail with reference to Examples, but the present invention is not limited by these Examples.

Example 1

A 50 μm thick polyimide film (Upilex 50S available from Ube Industries, Ltd .; modulus of elasticity: 6.4 × 10 ⁹ N / m 2) is formed in the vacuum chamber, and aluminum reduces by 1.33 Pa or less in the chamber. It was heated to 1220 ° C. under a reduced pressure and deposited aluminum on one side of the polyimide film to form an antistatic layer having a thickness of 2000 kPa. The resulting polyimide film and an inwardly facing antistatic layer and a laminate composed of a 125 μm thick viscoelastic layer made of an acrylic pressure sensitive adhesive were passed through a pair of rubber rolls to produce a laminated sheet. A square damper with a side length of 2 mm is blanked from the laminated sheet and manufactured.

Example 2

Water-soluble polyaniline is applied to one side of a 50 μm thick PET film (Lumilar S10; modulus: 3.9 × 10 ⁹ N / m 2 available from Toray Industries, Ltd.) and dried to form an antistatic layer having a thickness of 0.1 μm. . The resulting coated polyimide film, an inwardly facing antistatic layer, and a laminate consisting of a 125 μm thick viscoelastic layer made of an acrylic pressure sensitive adhesive were passed through a pair of rubber rolls to produce a laminated sheet. The damper is produced by blanking the laminated sheets in the same manner as in Example 1.

Example 3

The damper is manufactured in the same manner as in Example 1 except that the polyimide film and the viscoelastic layer are combined with the antistatic layer on the outside thereof.

Example 4

The damper is manufactured in the same manner as in Example 2 except that the polyimide film and the viscoelastic layer are combined with the antistatic layer on the outside thereof.

Comparative Example 1

The damper is manufactured in the same manner as in Example 1 except that the antistatic layer is not formed on the PET film.

Comparative Example 2

The damper is manufactured in the same manner as in Example 1 except for using a stainless steel sheet (SUS304) having a thickness of 25 μm that is not subjected to an antistatic treatment.

The dampers produced in the examples and comparative examples are inspected to measure the height of the burrs. In addition, the surface resistance, charge amount, half life and damping characteristics of the damper are measured as follows. The results are shown in Table 1.

① Burr height formed by blanking

The acrylic adhesive is removed from the 2 mm square sample (damper) and the thickness of the cut edge of the constraint layer is measured with a dial gauge. The difference between the thickness after the blanking and the thickness before the blanking is calculated as the height of the burr. Burr heights of 10 μm or less are taken as reference values to judge the samples to have satisfactory blanking processability.

② surface resistance

The surface resistance of the restraint layer is measured with a resistance meter High Rester (MCP-HT 250 manufactured by Mitsubishi Chemical Co. Ltd.) and a resistance meter Low Rester (MCP-T 250 manufactured by Mitsubishi Chemical Co. Ltd.). In Table 1, the samples whose surface resistance exceeded the measurable upper limit (1 × 10 ¹⁴ Pa /?) Are indicated as “> 1 × 10 ¹⁴ Pa /?”. 1 × 10 ¹⁰ Ω /? Or lower surface resistance is taken as a reference value for determining a satisfactory sample.

③ Charge amount and half life

The amount of charge on the side of the viscoelastic layer of the sample (laminate) is measured with a static honest meter (S-5109, manufactured by Shishido Electro K.K.). The amount of charge of the applied voltage of 10 mA and the time required to reduce the charge amount in half are measured. Samples with a half-life of 60 seconds or less are determined to be satisfactory.

④ Damping characteristic

A sample (damper) is attached to a 50 μm thick stainless steel substrate (SUS304), and the loss factor is measured with an FFT analyzer (CF-5220 manufactured by Ono Sokuki K.K.). More specifically, the FFT analyzer is set to give a vibration of frequency of 3 Hz at a measurement temperature of 25 ° C., and the loss factor is obtained by the half width method. A loss factor of 0.1 or more is taken to have practical damping characteristics and as a reference value for determining satisfactory samples.

⑤ Comprehensive Evaluation

A sample is evaluated as follows based on the result of the measurement mentioned above.

A: The sample met all the reference values of the properties and was found to be particularly good at each property.

B: The sample meets all the reference values of the properties.

C: The sample does not meet all the reference values of the properties.

Burr height (㎛) Surface resistance (Ω /?) Charge amount Half-life (seconds) Loss factor Comprehensive evaluation Example 1 3 5 × 10 ⁰ 18 30 0.16 A Example 2 5 3 × 10 ⁵ 19 50 0.12 B Example 3 3 5 × 10 ⁰ 20 120 0.16 B Example 4 5 3 × 10 ⁵ 20 200 0.12 B Comparative Example 1 3 ＞ 1 × 10 ¹⁴ 22 7000 0.16 C Comparative Example 2 35 1 × 10 ⁰ 16 30 0.17 C

The damper of the embodiment has a small burr height and is hardly charged as can be seen from the result of the measured values at the surface resistance, the charge amount and the half life. They also exhibit good damping properties. In contrast, the damper of Comparative Example 1, in which the restraint layer is not subjected to the antistatic treatment, has a small burr height, but is easily charged when compared with the dampers of Examples and Comparative Examples 2. The damper of Comparative Example 2, which uses a stainless steel sheet as the restraint layer, has excellent damping characteristics and is almost uncharged, as can be seen from the result of the measured values of surface resistance, charge quantity and half-life, but the burr height is very high, so that blanking workability is achieved. Poor

As described above, the damper of the present invention includes a laminate of a restraint layer and a viscoelastic layer, wherein the restraint layer is a plastic film, and an antistatic treatment is applied to at least one surface of the film. Since the plastic film used as the restraint layer is antistatically treated, the damper of the present invention is not electrostatically charged and does not damage the head as compared with the damper using the plastic antistatic layer which has not been subjected to the antistatic treatment.

Since the constraint layer is a plastic film, little burr is formed in the damper at the time of blanking. When stacked on at least a portion of the head suspension, the damper can eliminate or greatly reduce the vibration of the head suspension, thereby effectively preventing errors in reading and writing of the head.

Since the restraint layer is formed on the side of the restraint layer in contact with the viscoelastic layer, a high antistatic effect is exerted during frictional charging when the damper is peeled off the release sheet, and the antistatic layer is protected from external influences such as scratches or oxidation. do.

In the case where the antistatic layer is a layer formed by metal deposition, the damper has a very low surface resistance. In the case where the antistatic layer is a conductive resin coating film, the layer is formed relatively easily and becomes transparent or translucent so that a change in color is hardly caused.

When the plastic film is a polyimide film having an elastic modulus of 4.9 × 10 ⁹ N / m 2 or more, the damper is competitive in price and excellent in damping characteristics.

The damper of the present invention does not interfere with the characteristics of the head suspension as a spring, eliminates static electricity charging, is excellent in workability during blanking, can reduce manufacturing cost and weight, and does not cause damage to the head.

The head suspension of the present invention, to which the damper of the present invention is attached at least a part, has the above-described effect provided by the damper, and effectively prevents read and write errors of the head.

Although the present invention has been described with reference to the preferred embodiments, the disclosure of the preferred embodiments may be modified in detail and in combination and arrangement of components without departing from the spirit and scope of the invention as set forth in the appended claims. have.

According to the present invention, the damper of the present invention does not interfere with the characteristics of the head suspension as a spring, eliminates the charge of static electricity, is excellent in workability during blanking, can reduce manufacturing cost and weight, and damages the head The head suspension of the present invention, in which the damper of the present invention is attached to at least a portion thereof, has the above effect provided by the damper, and effectively prevents read and write errors of the head.

Claims (6)

In the damper attached to the head suspension of the recording disc drive, A constraint layer, A viscoelastic layer (a viscoelastatic layer) laminated on the constraint layer, The restraint layer includes a plastic film, and at least one surface of the plastic film is subjected to an antistatic treatment. Damper. The method of claim 1, The antistatic treatment is performed on the surface of the restraint layer in contact with the viscoelastic layer Damper. The method of claim 1, The antistatic treatment is performed by forming an antistatic layer by metal deposition. Damper. The method of claim 1, The antistatic treatment is achieved by coating with a conductive resin Damper. The method of claim 1, The plastic film comprises a polyimide film having an elastic modulus of 4.9 × 10 ⁹ / m 2 or more Damper. A head suspension for a head of a recording disk drive, comprising: a damper according to any one of claims 1 to 5 attached to at least a portion of the head suspension. Head suspension.