WO2006109512A1

WO2006109512A1 - Laminate for hdd suspension

Info

Publication number: WO2006109512A1
Application number: PCT/JP2006/305933
Authority: WO
Inventors: Kohji Kinashi; Takaki Suzuki; Hisayoshi Mukai; Teppei Nishiyama
Original assignee: Nippon Steel Chemical Co., Ltd.
Priority date: 2005-03-31
Filing date: 2006-03-24
Publication date: 2006-10-19
Also published as: TW200702160A; JPWO2006109512A1

Abstract

A laminate for HDD suspension dealing with fine pitch wiring required for a suspension material and realizing a hard disc drive (hereinafter referred to HDD) capable of stable recording or reading of signals even at a high rate. The laminate for HDD suspension is characterized in that a spring layer having a longitudinal modulus of elasticity in the range of 100-1000 Gpa and a conductivity in the range of 10-100% IACS, an insulating layer and a conductor layer are laminated sequentially.

Description

Specification

Laminate for HDD suspension

Technical field

The present invention relates to a suitable laminate as a suspension board for a hard disk drive (hereinafter referred to as HDD). Specifically, the present invention relates to a high-functional laminate that can obtain stable electrical characteristics in the miniaturization of wiring required for suspension materials.

Background art

[0002] The production volume of HDDs has been steadily increasing due to the demand for conventional personal computers and servers as they are installed in new applications such as music, home appliances, and car navigation systems. In addition, HDDs are expected to become smaller in size in the future, and the suspension part of the flexure blank equipped with a head that reads and writes magnetic records in the HDD will also be reduced in size and wiring. Thinning is progressing.

[0003] As one of them, the replacement of the conventional wire type suspension using the wire wire to the wireless type suspension in which the wiring is integrated has progressed, and the load of the wire wire which has been a problem in the past has become uneven. By eliminating the instability based on the suspension, the suspension's levitation posture has been greatly improved, enabling the technology to be equipped with a smaller slider. The technology to mount this miniaturized slider has become possible, and technology that dramatically improves the write capacity such as track density and linear recording (bit) density has been achieved. However, most of the wire-type suspensions that have been used in the past have been replaced by wiring-integrated suspensions that have stable buoyancy and positional accuracy with respect to the disk that is the storage medium. Among these integrated wiring suspensions, there is a type called the TSA (Trace Suspension Assembly) method in which a laminated body of stainless steel foil-polyimide resin copper foil is processed into a predetermined shape by etching.

[0004] The TSA suspension can easily form flying leads by laminating high-strength alloy copper foil, and has a high degree of freedom in shape processing. It is widely used because it is relatively inexpensive and has good dimensional accuracy. WO98 / 08216 discloses an HDD suspension laminate in which a polyimide resin layer and a conductor layer are sequentially formed on a stainless steel substrate.

[0005] On the other hand, with an increase in storage capacity, an improvement in processing speed that shortens recording and reading time is one of the technical issues that are required next. In other words, it is necessary to exchange electrical signals at high speed using finer wiring. For this reason, the signal frequency becomes higher than the conventional one, and attenuation of the electric signal due to the influence of the high frequency circuit is observed, which hinders the speeding up. This is a problem that causes a response error between wirings called crosstalk due to the narrowing of wiring between wirings due to miniaturization. Japanese Patent Laid-Open No. 9-283930 discloses crosstalk noise of adjacent patterns in a microstrip structure. A structure and a manufacturing method of a multilayer printed wiring board for avoiding malfunction due to the above are disclosed.

Patent Document 1: Pamphlet of WO98 / 08216

Patent Document 2: JP-A-9-283930

Disclosure of the invention

Problems to be solved by the invention

An object of the present invention is to provide a laminate for an HDD suspension that can cope with the narrowing of wiring between fine wiring and can realize an HDD capable of recording and reading signals at high speed and stably. .

Means for solving the problem

[0007] As a result of intensive studies to solve such problems, the present inventors have reduced inductive coupling (mutual inductance) generated between the conductor layer and the panel layer that causes data loss. Therefore, the present invention has been completed by using a material having a higher conductivity than the conventionally used stainless steel as the panel layer.

[0008] That is, the present invention is in the range of the longitudinal elastic modulus force Sl00 to 100GPa and the conductivity is

A HDD suspension laminate comprising a spring layer, an insulating layer, and a conductor layer in a range of 10 to 100% IACS, which are sequentially laminated.

The present invention also provides an HDD suspension in which a panel layer, an insulating layer, and a conductor layer are sequentially laminated. The spring layer has a longitudinal elastic modulus in the range of 100 to 1000 GPa and a conductivity in the range of 10 to 100% IACS, and the spring layer has at least Fe as a main component. It consists of one or more metal layers selected from Cu, Al, Zn, Sn, Ή, or the above metals and Ni, Cr, Mg, Be, Mo, Zr, Si, C, Mn, P, It is a laminate for an HDD suspension that is made of an alloy layer made of an alloy of one or more selected from S and Co.

The invention's effect

[0009] The laminated body of the present invention has a predetermined longitudinal elastic modulus in order to serve as a spring material in place of the stainless steel foil generally used for the panel layer, and has excellent conductivity. Using the panel layer, the HDD suspension stack is formed by sequentially stacking the panel layer, insulating layer, and conductor layer, thus realizing an HDD that can record and read signals stably at high speed. In addition, crosstalk due to the generation of mutual inductance between the conductor layer and the panel layer can be reduced, and further, data loss can be suppressed. It is.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] The HDD suspension laminate of the present invention is a laminate in which a panel layer, an insulating layer, and a conductor layer are sequentially laminated, and has a longitudinal elastic modulus force of the spring layer in the range of 100 to 1000 GPa. Here, the longitudinal elastic modulus is an index of the panel property of the suspension material. If the longitudinal elastic coefficient of the panel layer is less than 100 GPa, the shape of the flare sharp rank on which the head is mounted cannot be maintained. Even if it is larger than 1000 GPa, there is no practical meaning. The longitudinal elastic modulus can be measured by the cantilever method according to ASTM E-756.

[0011] Also, the spring layer needs to have a conductivity in the range of 10 to 100% IACS. If it is smaller than this range, it will not be possible to suppress crosstalk and cause malfunction. On the other hand, a material cost of 100% IACS or higher is not preferable because the material cost increases. Note that the conductivity (% IACS) is expressed as% of the conductivity of each material when the conductivity is 100% when measured using the 4-probe method with International Annnealed Copper Standard. It is a thing. 100% IACS corresponds to 1.7241x10- ⁸ Ω 'm.

[0012] Materials suitably used for the panel layer include, for example, beryllium copper foil (for example, 25 beryllium copper: longitudinal elastic modulus 127 GPa, conductivity 25% IACS) and titanium copper (longitudinal elastic modulus 127 GPa, conductive Electricity 18-25% IACS).

The thickness of the spring layer is preferably about 10-50 / im. In other words, if it is less than ΙΟ μ πι, there is a risk that sufficient panel properties cannot be secured to suppress the flying height of the slider. Conversely, if it exceeds 50 μm, it may be difficult to lower the slider. .

In the laminate for HDD suspension of the present invention, it is preferable that the insulating layer is composed of an insulating resin layer. Specifically, polyimide, polyamideimide, polyetherimide or the like has an imide bond in its structure. It is good to have a polyimide resin. The thickness of the polyimide resin layer is 5 to 20 μπι, preferably 7 to 18 μπι. When the polyimide resin layer thickness is less than μm, the reliability of the electrical insulation is lowered and the dielectric property is deteriorated, and the crosstalk problem of the electric signal is promoted. If it exceeds 20 μπι, there will be a problem that it is difficult to perform patterning of the polyimide resin layer with high accuracy.

[0014] Further, the linear expansion coefficient of the polyimide榭脂layer ^{^{1 X 10- 5 ~3 X 10- 5}} / ° C, preferred properly in ^{^{1.5 X 10- 5 ~2.5 X 10- 5}} / ° C There should be. Linear expansion coefficient of the polyimide榭脂layer 1 X 10- ⁵ /. Be less than C, contrary to 3 X 10- ⁵ /. Even if it is larger than C, there is a problem that warpage tends to occur when the panel layer or conductor layer of the laminate is etched away.

[0015] Further, the laminate of the present invention has an adhesive strength at the interface between the insulating layer and the panel layer of 0.5 kN / m or more and an adhesive strength at the interface between the insulating layer and the conductor layer of 0.5 kN / m. It is preferable that it is more than m. Therefore, when the insulating layer is made of a polyimide resin layer, it is desirable that this polyimide resin layer has a certain degree of adhesion performance. Note that the upper limit of the adhesive strength at the interface between the insulating layer and the panel layer and at the interface between the insulating layer and the conductor layer is based on practical experience rules when using the circuit as a material for HDD suspension. Since it is sufficient if the circuit has sufficient adhesive strength not to peel off, lOkN / m or less is sufficient.

[0016] Incidentally, in general, polyimide resin layer linear expansion coefficient of the polyimide resin layer is more than 3 X 10- ⁵ / ° C, although tend to exhibit relatively good adhesive strength between panels layer and the conductive layer , polyimide resin layer of the linear expansion coefficient of ^{^{1 X 10- 5 ~3 X 10- 5}} / ° C , there is a tendency not exhibit good adhesion strength as described above. Therefore, as a good preferable embodiment of the polyimide resin layer in the present invention, the linear expansion coefficient 2.5 X 10- ⁵ / ° C or lower thermal expansion polyimide resin layer If, what is a multilayer structure comprising at least two layers of the linear expansion coefficient 3 X 10- ⁵ / ° C or more high thermal expansion polyimide resin layer is more preferably Yogu, linear expansion coefficient 3 X 10- ⁵ / ° and more first high thermal expansion polyimide resin layer C, a linear expansion coefficient 2.5 X 10- ⁵ / ° C or lower thermal expansion polyimide resin layer, a linear expansion coefficient of 3 X 10- ⁵ / ° C A three-layer structure composed of the second high thermal expansion polyimide resin layer is preferred. In addition, when the polyimide resin layer is formed of three or more layers, the ratio (ta / tb) of the total thickness (ta) of both outermost layers to the thickness (tb) of other intermediate layers It should be in the range of 0.1 to 0.5. The first high thermal expansion polyimide resin layer and the second high thermal expansion polyimide resin layer may be the same resin or different resins. In this way, a resin layer that satisfies both the conditions of low thermal expansion and high adhesiveness is obtained by combining the polyimide resin layer with a low thermal expansion polyimide resin layer and a high thermal expansion polyimide resin layer to form a multilayer structure. Can be formed.

[0017] The conductor layer in the present invention is preferably formed from an alloy copper foil. Here, the alloy copper foil refers to an alloy foil containing copper as an essential element and containing at least one kind of different elements other than copper, such as chromium, zirconium, nickel, silicon, zinc, and beryllium. The rate is over 90% by weight.

It is preferable to use an alloy copper foil having a copper content of 95% by weight or more. In addition, it is preferable that the copper foil before lamination has a tensile strength of 500 MPa or more and a conductivity of 65% or more. If the tensile strength of the conductor layer is less than 500 MPa, sufficient copper foil strength cannot be obtained when a flying lead is formed, and problems such as disconnection are likely to occur. If the conductivity is less than 65%, the noise generated from the copper foil resistor is dissipated as heat, making impedance control difficult and the transmission speed not satisfactory.

[0018] Next, an example of a method for producing a laminate of the present invention will be described. The means for obtaining the laminate of the present invention is not limited to the following method.

In manufacturing the laminated body, first, an insulating layer is formed by coating a polyimide resin solution on the panel layer serving as a base. The polyimide resin liquid can be applied by a known method, and is usually applied using an applicator. The polyimide resin solution may be obtained by dissolving the imidized polyimide resin in a solvent, but the polyimide resin precursor resin solution was used, and after application, the solvent was removed to some extent by preheating. After, imide by heat treatment It is preferable that Of course, when using an imidized polyimide resin solution, heat treatment for imidig is omitted.

[0019] After the polyimide resin layer is formed in this way, a rolled copper foil or an electrolytic copper foil having a thickness of 1 to 20/1111, a tensile strength of 500 MPa or more, and a conductivity of 65% or more to be a conductor layer is laminated. , 2 at a temperature of 80 ° C or higher, 3 to: pressurize in the range of 120 minutes. If the pressurization time exceeds 120 minutes, it is not preferable because it is difficult to obtain a stable laminate material in which warpage easily occurs due to heat elongation of the copper foil. Also, when the pressing time force is less than 3 minutes, sufficient peel strength cannot be obtained, which is preferable. A more preferable heating and pressing time is 10 to 100 minutes.

In addition, there is no problem even if a polyimide resin layer is formed on a rolled copper foil or an electrolytic copper foil serving as a conductor layer and a stainless steel foil is overlapped later.

[0020] Hereinafter, the present invention will be described more specifically based on examples. The abbreviations used in the synthesis examples are as follows.

PMDA: pyromellitic anhydride

BTDA: benzophenone-3,4,3 ', 4'-tetracarboxylic dianhydride

DSDA: Diphenylsulfone-3, 4,3 ', 4'-tetracarboxylic dianhydride

DA-NPG: 1,3-bis (4-aminophenoxy) -2,2-dimethylpropane

3,4, -DAPE: 3,4'-diaminodiphenyl ether

MABA: 4-Amino_N- (4-Amino-2-methoxyphenyl) -benzoamide

DAPE: 4,4'-diaminodiphenyl ether

APB: 1,3-bis (3-aminophenoxy) benzene

p-PDA: p-Phenylenediamine

DMAc: N, N_Dimethyloleacetamide

[0021] [Synthesis Example 1]

5.5 mol of DA-NPG and 3.5 mol of 3,4, -DAPE were weighed and dissolved in 25.5 kg of DMAc solvent with stirring in a 40 L planetary mixer. Next, 2.5 mol of PMDA and 5.0 mol of BTDA were added, and the polymerization reaction was continued for 3 hours at room temperature to obtain a viscous polyimide precursor A solution.

[0022] [Synthesis Example 2] 8.5 mole 1 ^ 88 and 2.0 mole 0-8? 6 was weighed and dissolved in 25.5 kg of solvent DMAc while stirring in a 40 L planetary mixer. Next, 8.6 mol of PMDA was added, and the polymerization reaction was continued by stirring at room temperature for 3 hours to obtain a viscous polyimide precursor B solution.

[0023] [Synthesis Example 3]

5.5 mole eight? 8 and 3.9 moles of ?? 0-8 were weighed and dissolved in 25.5 kg of solvent DMAc with stirring in a 40 L planetary mixer. Next, 5.4 moles of DSDA and 2.3 moles of 40 dollars were added, and the polymerization reaction was continued for 3 hours at room temperature to obtain a viscous polyimide precursor solution.

[0024] [Evaluation method based on the presence or absence of crosstalk]

For the HDD suspension laminates A to E obtained in the following Examples 1 to 4 and Comparative Example 1, the presence or absence of occurrence of crosstalk was evaluated by the following method.

First, using a photo-etching technology on the conductor layer, create a lead wire with a width of 25 zm for both the line width and the distance between the lines. HDD equipped with a magnetic writing device and magnetic reading device for reading and writing information on the HDD board Create a flexure for use. Next, connect a transmitter that can freely change the frequency to the above-mentioned magnetic writing circuit (Toyo Tecini Power Co., Ltd .: frequency response analyzer type 1260, NF circuit design block: frequency characteristic analyzer FRA5096), and from 1 Hz from one side Apply AC voltage while changing the frequency up to 15 MHz, measure the voltage output from the other, calculate the ratio of the applied output voltage, and if there is no attenuation of the applied voltage, the crosstalk is assumed and the attenuation Is recognized as crosstalk. Example 1

[0025] The polyimide precursor A obtained in Synthesis Example 1 using copper foil (manufactured by Nikko Materials Corporation, NK-120, copper foil thickness 12 μm, strength 55 6 MPa, conductivity 79%) as the conductor layer Is applied to the copper foil so that the thickness after curing is 1 β m, dried at 110 ° C for 3 minutes, and then the solution of the polyimide precursor B obtained in Synthesis Example 2 thereon. The thickness after curing is 7.5 μm, dried at 10 ° C for 10 minutes, and then the polyimide precursor A solution obtained in Synthesis Example 1 is further cured. Was applied to 1.5 μm and dried at 110 ° C. for 3 minutes. Further, the imidization is completed by a heat treatment in several steps in a range of 130 to 360 ° C. for 3 minutes each, and in order from the copper foil, the first polyimide resin layer (high thermal expansion polyimide resin), Second An insulating layer (resin layer) having a multilayer structure including a polyimide layer (low thermal expansion polyimide resin) and a third polyimide resin layer (high thermal expansion polyimide resin) was formed. The first layer of polyimide resin layer and the third layer of the polyimide resin layer is the same, the linear expansion coefficient is either 4.0 X 10- ⁵ / ° C, the second layer of the polyimide resin layer the linear expansion coefficient of a 1.5 X 10- ⁵ / ° C. Further, the insulating layer total thickness is 10 zm, linear thermal expansion coefficient of the entire insulating layer was 1.7 X 10- ⁵ / ° C. For measurement of the linear expansion coefficient, the corresponding insulating layer was heated to 250 ° C using a thermomechanical analyzer (manufactured by Seiko Electronics Co., Ltd.), held at that temperature for 20 minutes, and then 10 ° The average linear expansion coefficient from 240 ° C to 100 ° C was determined by cooling at a rate of C / min.

Next, beryllium copper foil (manufactured by Nippon Zushi Co., Ltd., 25 beryllium copper, thickness 20 zm, longitudinal elastic modulus 127 GPa, conductivity 25% IACS) was used as the panel layer, and this beryllium copper foil was obtained above. Laminated body A for HDD suspension was obtained by superimposing on the polyimide surface (insulating layer) and thermocompression bonding using a vacuum press machine under conditions of surface pressure of 7 MPa, temperature of 315 ° C, and press time of 80 minutes. Example 2

[0027] Instead of the beryllium copper foil used as the panel layer in Example 1, a titanium copper foil (manufactured by Nikko Metal Co., Ltd., hyper titanium copper XSH, thickness 20 xm, longitudinal elastic modulus 127 GPa, conductivity 18-25% IACS) was used. A laminate B for HDD suspension was obtained in the same manner as in Example 1 except that it was used. Example 3

[0028] Polyimide precursor C obtained in Synthesis Example 3 using copper foil (manufactured by Nikko Materials Company, NK-120, copper foil thickness 12 / m, strength 55 6MPa, conductivity 79%) as the conductor layer Is applied to the copper foil so that the thickness after curing is 1 β m, dried at 110 ° C for 3 minutes, and then the solution of the polyimide precursor B obtained in Synthesis Example 2 thereon. Was applied to a thickness of 7.5 / m after curing, dried at 110 ° C for 10 minutes, and then the polyimide precursor A solution obtained in Synthesis Example 1 was further cured. It was applied to 1.5 μm and dried at 110 ° C. for 3 minutes. Further, the imidization is completed by a heat treatment in several steps in a range of 130 to 360 ° C. for 3 minutes each, and in order from the copper foil, the first polyimide resin layer (high thermal expansion polyimide resin), An insulating layer (resin layer) having a multilayer structure provided with a second polyimide layer (low thermal expansion polyimide resin) and a third polyimide resin layer (high thermal expansion polyimide resin) was formed. The first layer above Linear expansion coefficient of the resin layer of the polyimide resin layer is 4.2 X 10- ⁵ / ° C, the linear expansion coefficient of the second layer of the polyimide resin layer is 1.5 X 10- ⁵ / ° C, the third layer of the polyimide linear expansion coefficient of the resin layer 4. was 0 X 10- ⁵ / ° C. Further, the insulating layer total thickness is 10 / im, linear thermal expansion coefficient of the entire insulating layer was 1.7 X 10- ⁵ / ° C.

[0029] Next, beryllium copper foil (manufactured by Nippon Choshi Co., Ltd., 25 beryllium copper, thickness 20) was used as the panel layer.

(tm, longitudinal elastic modulus 127GPa, conductivity 25% IACS), superposed on the polyimide surface (insulating layer) obtained above, using a vacuum press machine, surface pressure 7MPa, temperature 315 ° C, press time 80 minutes The laminate C for HDD suspension was obtained by thermocompression bonding under the conditions described above.

Example 4

[0030] Instead of the beryllium copper foil used as the panel layer in Example 3, titanium copper foil (manufactured by Nikko Metal Co., Ltd., Hyper Titanium Copper XSH, thickness 20 μπι, longitudinal elastic modulus 127 GPa, conductivity 18 25% IACS) was used. A laminate D for HDD suspension was obtained in the same manner as in Example 3 except that it was used.

[0031] [Comparative Example 1]

In the same manner as in Example 1 except that stainless steel foil (manufactured by Nippon Steel Corp .: SUS-304 longitudinal elastic modulus 200 GPa, conductivity 2.4% IACS) was used instead of the beryllium copper foil as the panel layer in Example 1. As a result, a laminate E for HDD suspension was obtained.

With respect to the HDD suspension laminate AE obtained in Examples 14 and Comparative Example 1 above, the presence or absence of occurrence of crosstalk was evaluated by the method described above. The results are shown in Table 1.

[0033] [Table 1] Cross 1 occurrence

Example 1 fl½

Example 2 iffic I

Example 3

Example 4 ^ ff

Comparative example 1 Yes

Claims

The scope of the claims

[1] A panel layer, an insulating layer, and a conductor layer having a longitudinal elastic modulus in the range of 100 to 1000 GPa and an electrical conductivity in the range of 10 to 100% IACS are sequentially laminated. Laminate for HDD suspension.

[2] The laminate for an HDD suspension according to claim 1, wherein the panel layer is a metal layer composed of at least one selected from Fe, Cu, Al, Zn, Sn, and Ti. body.

[3] The panel layer is made of at least one metal selected from Fe, Cu, Al, Zn, Sn, and Ti and Ni, Cr, Mg, Be, Mo, Zr, Si, C, 2. The HDD suspension laminate according to claim 1, which is an alloy layer made of an alloy of one or more selected from Mn, P, S, and Co.

[4] The laminate for an HDD suspension according to claim 1, wherein the total thickness of the panel layer, the insulating layer, and the conductor layer is 3 to 200 μm.

[5] insulating layer is in the range of linear thermal expansion coefficient of ^{^{1 X 10- 5 ~3 X 10- 5}} / ° C, and wherein the dielectric constant of 4.0 or less of the insulating resin layer The laminate for an HDD suspension according to claim 1.

6. The laminate for HDD suspension according to claim 1, wherein the insulating layer is an insulating resin layer made of polyimide resin.

[7] Adhesive strength at the interface between the insulating layer and the panel layer and adhesive strength at the interface between the insulating layer and the conductor layer are both 0.5 kN / rr! HD according to claim 1, characterized in that it is in the range of ~ lOkN / m

D Suspension laminate.