JP2002025213A - Method for manufacturing wireless suspension blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a wireless suspension blank which can be worked with high accuracy at a low cost. SOLUTION: In the method for manufacturing the wire suspension blank by using a laminate of three-layered composition laminated with a conductive layer 3 through an electrically insulating layer 2 on a metallic layer 1 for developing a spring characteristic, the laminate of which the insulating layer 2 is formed of a core insulating layer and adhesive layers laminated on both surfaces thereof and in which the ratio of the respective layers of the insulating layers 2 having a high etching rate and a low etching rate ranges from 6:1 to 1:1 is used. The method described above includes a process step of working the metallic layer 1 and the conductive layer 3 respectively by a photoetching method and a process step of working the insulating layer 2 by forming resist images in order to work the insulating layers and wet etching according to the resist images. The process step of working the metallic layer and the conductive layer by the photoetching method is included and the insulating layer 2 is worked by the wet etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the field of technology for manufacturing a wireless suspension blank used in a data storage device such as a hard disk drive (hereinafter referred to as an HDD).

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 2000-49195 discloses a conventional technique relating to a method of manufacturing this kind of electronic component member. This document does not specifically describe a method for manufacturing a wireless suspension blank for an HDD, but discloses a method for manufacturing a member for an electronic component as described below.

In this manufacturing method, the laminate is made of a metal foil laminated on both sides of a polyimide film.
Layers are used. And this manufacturing method forms a resist pattern on each of the metal foils laminated on both sides of the polyimide film, and after etching both metal foils simultaneously with an etchant, peeling off the resist pattern, and then removing one of the resist patterns. The polyimide film is patterned by plasma etching using the metal foil as a mask, and thereafter, by removing the metal foil used for the mask, a laminate of the patterned polyimide film and the patterned metal foil is formed. An electronic component member is obtained. And this effect can be manufactured at low cost because the plate making only needs to be performed once, and it is possible to obtain a high quality product in which the pattern of the polyimide film and the pattern of the metal foil are laminated with good positional accuracy. Things.

[0004]

However, in the above-described method, wet etching is performed on the metal foils on both sides of the polyimide film in the three-layer laminate by using an etchant.
The processing of the polyimide film, which is an insulating layer, is performed by dry etching such as plasma etching, so that there is a problem that the processing cost by the dry etching is high. Moreover, as described below, it is difficult to perform low-cost wet etching instead of dry etching on a polyimide film.

[0005] In the laminate used in the above-described manufacturing method, the metal layer and the insulating layer need to have the same coefficient of thermal expansion in order to reduce the warpage of the laminate. For this purpose, it is desirable to use a low-expansion polyimide resin or the like as the insulating layer.

However, since low expansion polyimide is generally not thermoplastic, it has poor adhesion to a metal layer, and it is difficult to obtain an adhesion that can withstand practical use. Therefore, it is known to use a thermoplastic polyimide resin or epoxy resin having good adhesion to the metal layer as an adhesive layer between the metal layer and the low-expansion polyimide. As the adhesive used as a part of the insulating layer in the laminated body for use, a polyimide resin is used because it is necessary to ensure high insulation reliability. In order to impart adhesiveness to the polyimide resin, it is common to give thermoplasticity, but if a flexible structure that gives thermoplasticity is introduced into the skeleton of the polyimide resin, the chemical resistance will be strong Tend to become
Therefore, such a resin tends to be inferior in etching suitability by a wet process, and is apart from the etching rate of the core insulating layer. The term "etching rate" as used herein refers to a decrease in film thickness per unit time caused by etching.

By the way, low expansion polyimide is used as a core insulating layer, and polyimide having adhesiveness is used as an adhesive layer.
When these insulating layers are combined and laminated to form an insulating layer composed of a plurality of layers (for example, an adhesive layer / core insulating layer / adhesive layer, an adhesive layer / core insulating layer), When an etching process is performed by a wet process, the adhesive layer tends to have a low chemical resistance because of its high chemical resistance.However, since the core insulating layer is easily etched, the etching of the entire insulation does not proceed uniformly. There is a problem that the etching shape is not uniform. As described above, making the etching rates of the core insulating layer and the adhesive layer of the insulating layer in the laminated body for the wireless suspension blank appropriate and improving the adhesiveness of the adhesive layer are contradictory properties. Yes, it is difficult to achieve both.

[0008] Therefore, in the conventional laminated body for a wireless suspension blank, the etching conditions in the wet process are not known, and it is difficult to set the conditions for uniform etching even in the wet etching. At present, the insulating layer is etched by the used dry process.

The present invention has been made in view of the above background, and an object of the present invention is to provide a method of manufacturing a wireless suspension blank that can be processed at a low cost and with high precision. .

[0010]

SUMMARY OF THE INVENTION The present applicant discloses in Japanese Patent Application No. 2000-186564 that a wet etching of an insulating layer should be performed accurately with respect to a laminate for manufacturing a wireless suspension blank which is an object of the present invention. The application has already been filed and the contents are as follows. That is, the insulating layer is formed of two or more resin layers, and the ratio of the high etching rate to the low etching rate of each layer of the insulating layer is in the range of 6: 1 to 1: 1, preferably 4: 4. In the range of 1 to 1: 1, a good etching shape can be obtained. Therefore, in the present invention, by using an insulating layer having such a configuration for the insulating layer in the laminate, a favorable etching shape is obtained when the insulating layer is wet-etched.

That is, the method for manufacturing a wireless suspension blank of the present invention uses a three-layer laminate in which a conductive layer is laminated via an electrical insulating layer on a metal layer exhibiting spring characteristics. A method for manufacturing a wireless suspension blank, wherein the insulating layer is formed from a core insulating layer and an adhesive layer laminated on both surfaces thereof, and a ratio of a high etching rate to a low etching rate of each layer of the insulating layer is reduced. Using a laminate in the range of 6: 1 to 1: 1 and preferably in the range of 4: 1 to 1: 1; processing the metal layer and the conductive layer by photoetching, respectively; Forming a resist image for processing the insulating layer, and processing the insulating layer by wet etching according to the resist image.

The adhesive strength of the adhesive layer to the metal layer, the conductive layer and the core insulating layer is at least 300 g / c.
It is preferable to use a laminate having m.

It is preferable to use a laminate in which the ratio of the thickness of the core insulating layer to the thickness of the adhesive layer is 4: 1 at the maximum.

It is preferable to use a laminate in which at least one layer constituting the insulating layer is made of a polyimide resin, or to use a laminate in which all the layers constituting the insulating layer are made of a polyimide resin.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a process chart showing an example of a procedure for manufacturing a wireless suspension blank for an HDD. Each of the steps will be described below in turn.

FIG. 1A shows a laminate for forming a wireless suspension blank for an HDD. This laminate has a metal layer 1 exhibiting spring characteristics.
Is formed by laminating Cu (copper), which is a conductive layer 3, on an SUS (stainless steel) via an insulating layer 2 by a lamination method. The insulating layer 2 used here comprises a core insulating layer and an adhesive layer laminated on both surfaces thereof.

FIG. 1B shows a state where a dry film resist 4 as a photosensitive material is laminated on both surfaces of the metal layer 1 and the conductive layer 3, and the dry film resist 4 is exposed and developed through a mask. The resist 4 is patterned. The resist is preferably a dry film resist, but a liquid resist such as casein may be used.

FIG. 1C shows a state where the metal layer 1 and the conductive layer 3 are etched through the patterned dry film resist 4. In this case, the metal layer 1 and the conductive layer 3 are etched one by one in order by a single-sided lapping method using a general etching solution composed of iron chloride.

FIG. 1D shows a state in which the dry film resist 4 has been peeled off with a stripping solution composed of sodium hydroxide after the metal layer 1 and the conductive layer 3 have been etched. As shown in the figure, a three-layer laminate in which the metal layer 1 and the conductive layer 3 are patterned on both surfaces of the insulating layer 2 is obtained.

FIG. 1E shows that the insulating layer 2 is processed by wet etching, so that the insulating layer 2 is formed on both the lower surface of the patterned metal layer 1 and the upper surface of the conductive layer 3.
Shows a state in which an insulating layer processing resist 5 is formed in a region where a mark is left. For this purpose, a resist 5 for processing an insulating layer is formed on both sides by dip coating, roll coating, die coating, laminating, or the like, and is exposed and developed according to a predetermined mask pattern. The insulating layer processing resist 5 may be formed by a printing method instead of the resist exposure / development method.

FIG. 1F shows a state in which the insulating layer 2 has been processed by wet etching. The patterned laminate may be processed by wet etching on each side, or may be processed by wet etching on both sides simultaneously. Here, when wet etching is performed on each side, there is an effect that the cross-sectional shape of the etched insulating layer is finished finely, and when wet etching is performed on both sides simultaneously, there is an effect that the processing time can be shortened.

FIG. 1G shows a state in which the processing of the insulating layer 2 is completed by removing the insulating layer processing resist 5 used as a mask material for wet etching. In this stripping step, stripping with a high-temperature alkali solution of 1 to 20% by weight of sodium hydroxide at 50 to 70 ° C. is generally performed. However, when the polyimide or the like used has poor alkali resistance, an organic alkali such as ethanolamine is removed. Good to use.

Finally, although not shown, a plating resist is formed on the wiring portion of the gimbal suspension made of the flexible substrate formed by the above method, and the Au plating is formed on the conductive wiring portion exposed from the plating resist. Is formed, and a cover layer is formed as a protective layer at a necessary portion of the wiring portion. Au plating is a surface treatment for electrical connection between the magnetic head slider and the suspension (not shown) and electrical connection from the suspension to the control side, and Au plating is preferable, but not limited thereto. Ni / Au plating may be used, or solder plating or printing may be used instead. For example, N
When performing i-plating, a gloss bath, a matte bath, and a semi-gloss bath can be selected.

As described above, the manufacture of the HDD wireless suspension blank is completed by the procedure shown in FIG. Thereafter, although not shown, assembly processing such as mechanical processing is finally performed to complete the wireless suspension for the HDD.

[0025]

EXAMPLES (Example 1) A core insulating layer having a thickness of 12.5
μm polyimide film (Kanebuchi Chemical Co., Ltd. “AP
IKAL NPI ”), and a polyimide varnish (“ EN-20 ”manufactured by Shin Nippon Rika Co., Ltd.) was formed as an adhesive layer on both sides such that the film thickness after drying was 2.5 ± 0.3 μm. To form a film with an adhesive layer (insulating layer). Then, the film with the adhesive layer is made of SU having a thickness of 20 mm.
S (Nippon Steel “304HTA foil”) and thickness 18μ
m copper alloy foil ("C7025" manufactured by Ohlin Co., Ltd.) (the rough surface of the copper foil is turned to the film side), a pressure of 1 MPa is applied, and vacuum pressing is performed at 300 ° C. for 10 minutes to form a metal layer:
Insulating layer: A laminate of conductive layers was formed.

Here, the etching rate of the core insulating layer and the adhesive layer in the insulating layer is determined by an alkali-amine based polyimide etchant ("TPE" manufactured by Toray Engineering Co., Ltd.).
-3000 "), the values were about 20 μm / min and 11 μm / min, respectively, and the ratio was 20:11. The change in the film thickness is obtained by measuring the film thickness at a location substantially the same as the location where the initial film thickness was measured by using a stylus-type thickness gauge (Sloa
n “Dektak 160” manufactured by Technology
00 ”), and the value obtained by subtracting the film thickness after immersion from the initial film thickness was calculated as a film reduction amount.

With respect to the above laminate, the upper surface of the copper alloy foil and S
After laminating an acrylic dry film resist ("AQ-5038" manufactured by Asahi Kasei Corporation) on both surfaces of the lower surface of the US, both dry film resists were exposed and developed according to a predetermined photomask pattern, and then patterned. . Exposure is 30 to 60 g-rays.
mJ / cm ² at 30 ° C., 1 wt% Na ₂ C
It was spray-developed with O _3.

Next, the copper foil was etched using a ferric chloride solution while masking the SUS side, and then the dry film resist was stripped with a stripping solution containing sodium hydroxide. Subsequently, after masking the copper foil side and etching one surface of SUS using a ferric chloride solution, the dry film resist was stripped with a stripping solution made of sodium hydroxide. Thereby, a copper foil was patterned on one surface of the polyimide film, and a three-layer laminate in which SUS was patterned on the other surface was obtained.

Subsequently, a wiring portion is formed by the conductive layer.
Of polyimide film and patterned S
Leave polyimide on both sides with the US polyimide bottom
A polyimide processing resist was formed in the region. Specifically
Is an acrylic dry film resist (“A
Q-5038 ”) was laminated at 100 ° C.
Exposure 30-60 mJ / cm depending on line^TwoAnd development
30 ° C, 1wt% Na _TwoCO_ThreeAnd spray developed.

Then, the polyimide film and the adhesive layer were removed by spraying an etching solution ("TPE-3000" manufactured by Toray Engineering Co., Ltd.) on both sides of the patterned laminate. Thereafter, a spray pressure of 1 wt.
The dry film resist was peeled off in kg. Observation of the laminate after wet etching in this way,
Both the core insulating layer and the adhesive layer were etched well. When the polyimide film and the adhesive layer are removed by dipping (immersion) with the same etching solution,
A better cross-sectional shape was obtained.

The wiring portion of the laminate formed as described above was plated with gold as a finishing finish. Gold plating was performed in a cyan gold plating bath manufactured by Japan High Purity Chemical. Specifically, using Temper resist Ex, 65 ° C.
And a current density Dk of 0.4 A / dm ² was applied for about 4 minutes to form a 1 μm thick film. Then, an epoxy-based cover layer was formed as a protective layer at a necessary portion of the wiring portion to manufacture a wireless suspension blank for HDD. Of course, the cover layer is not limited to the epoxy type.

(Example 2) As a core insulating layer, a thickness of 12.
Example 1 except that a 5 μm polyimide film (“KAPTON EN” manufactured by Toray DuPont) was used.
A laminate having the same configuration as that described above was formed. The etching rates of the core insulating layer and the adhesive layer in this laminate were about 7 μm / min and 11 μm / min, respectively, and the ratio was 7:11.

Using this laminate, a wireless suspension blank was manufactured in the same process as in Example 1. As a result, both the core insulating layer and the adhesive layer were etched well.

Comparative Example 12.5 Thickness of Core Insulating Layer
μm polyimide film (Kanebuchi Chemical Co., Ltd. “AP
IKAL NPI ") and a polyamic acid varnish (" PAA-A "manufactured by Mitsui Chemicals, Inc.) as an adhesive layer.
Was applied so that the film thickness after drying was 2.5 ± 0.3 μm to obtain a film with an adhesive layer (insulating layer). And
The laminated body having the configuration was formed by laminating the same SUS as in Example 1. The etching rates of the core insulating layer and the adhesive layer in this laminate were about 20 μm / min and 1 μm / min, respectively, and the ratio was 20: 1.

Using this laminate, a wireless suspension blank was manufactured in the same process as in Example 1. As a result, the adhesive layer was not etched well, and was projected above the core insulating layer. .

[0036]

As described above, according to the present invention,
Since the processing of the polyimide resin, which is an insulating layer, is performed by wet etching, cost reduction can be achieved. As a result, a method of manufacturing a wireless suspension blank that can be processed at low cost and with high precision can be realized.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a manufacturing procedure of a wireless suspension blank for an HDD.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal layer 2 Insulating layer 3 Conductive layer 4 Resist 5 Insulating layer processing resist

Continuation of the front page (72) Inventor Yuko Kanzaki 1-1-1, Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd. (72) Inventor Kazuo Umeda 1-1-1-1, Ichigaga-cho, Shinjuku-ku, Tokyo Dai Nippon Printing Co., Ltd. (72) Inventor Satoshi Sasaki 1-1-1, Ichigaya-Kagacho, Shinjuku-ku, Tokyo F-term within Dai Nippon Printing Co., Ltd. 5D042 NA01 PA10 TA07 5D059 AA01 BA01 DA31 DA36 EA08

Claims (7)

[Claims] 1. A method for manufacturing a wireless suspension blank using a three-layer laminate in which a conductive layer is laminated via an electrical insulating layer on a metal layer exhibiting spring characteristics, The insulating layer is formed of a core insulating layer and an adhesive layer laminated on both sides of the core insulating layer, and a ratio of a high etching rate to a low etching rate of each of the insulating layers is in a range of 6: 1 to 1: 1. Using a laminate, a step of processing the metal layer and the conductive layer by a photo-etching method, and forming a resist image for processing the insulating layer, and forming the insulating layer by wet etching according to the resist image. A method for manufacturing a wireless suspension blank, comprising a step of processing. 2. The method for manufacturing a wireless suspension blank according to claim 1, wherein a laminated body having a ratio of a high etching rate to a low etching rate of each of the insulating layers is in a range of 4: 1 to 1: 1. . 3. The method for manufacturing a wireless suspension blank according to claim 1, wherein a laminate having an adhesive strength of the adhesive layer to the metal layer, the conductive layer and the core insulating layer of at least 300 g / cm is used. 4. The method of manufacturing a wireless suspension blank according to claim 1, wherein a laminate having a thickness ratio of the core insulating layer and the adhesive layer of each one layer of at most 4: 1 is used. 5. The method for manufacturing a wireless suspension blank according to claim 1, wherein a laminate in which at least one layer constituting the insulating layer is a polyimide resin is used. 6. The method of manufacturing a wireless suspension blank according to claim 1, wherein a laminate in which all the layers constituting the insulating layer are made of a polyimide resin is used. 7. The method for manufacturing a wireless suspension blank according to claim 1, wherein the ratio of the etching rate of the insulating layer is a value obtained when etching is performed with an alkaline solution.