JP2002157725A - Method for manufacturing wireless suspension blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a wireless suspension blank which is bonded to an insulating layer with high adhesion strength and with excellent workability at low cost while solving the conventional problem. SOLUTION: The method for manufacturing the suspension blank uses a laminated body having a three-layer construction wherein a metal layer developing a spring characteristic and a conductive layer are laminated via an electrically insulating layer consisting of polyimide resin. The insulating layer is formed by using a laminated body constituted of a core insulating layer and adhesive material layers laminated on the both surfaces thereof. A stage for inspecting the adhesion strength of each layer of the laminated body, a stage for working the metal layer and a stage for working the conductive layer to form a wiring part are included in the method for manufacturing the suspension blank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a data structure using a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin. The present invention relates to a method for manufacturing a wireless suspension blank used in a storage device such as a hard disk drive (hereinafter, referred to as an HDD).

In particular, a step of using a laminate in which the insulating layer is composed of a core insulating layer and an adhesive material layer laminated on both sides thereof, and inspecting the adhesive strength of each layer of the laminate,
The invention relates to a method for manufacturing a wireless suspension blank, including a step of processing the metal layer, a step of processing the conductive layer to form a wiring portion, and a step of processing an electrically insulating material by wet etching. .

[0003]

2. Description of the Related Art In a conventional method of manufacturing a wireless suspension blank for an HDD, an insulating layer made of a polyimide resin as an electric insulating material is processed by performing dry etching such as plasma etching. There is a first problem that the processing cost by the dry etching is expensive.

Therefore, in the processing of an insulating layer made of a polyimide resin, attention was paid to low-cost wet etching instead of dry etching. However, when wet etching is performed, there is a second problem that the insulating layer made of a polyimide resin and the metal layer are easily separated. This is because, in the wiring layer of the HDD wireless suspension, there is a region where only the conductive layer serving as the wiring is formed by wet etching of the insulating layer, and sufficient adhesion force is required to stably support the wiring. Required.

[0005] The expansion and contraction ratios of the respective layers of the laminate due to heat, moisture and the like are different from each other. For this reason, when each layer of the laminated body is heated or absorbs moisture, the metal layer, the conductive layer, the core insulating layer in the insulating layer, or each layer of the adhesive material layer laminated on both surfaces of the core insulating layer. In some cases, a force may be generated in between, and peeling may occur. Further, the wet etching property of the insulating layer made of a polyimide resin and the adhesive strength between the insulating layer and the metal layer show a conflicting relationship. In other words, when trying to obtain good wet etching characteristics, the adhesive strength tends to be weak. Conversely, when trying to increase the adhesive strength, a phenomenon occurs in which good wet etching characteristics cannot be obtained.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is intended to provide a low-cost, high-quality processing of a wireless suspension blank which has a high adhesive strength to an insulating layer. It is intended to provide a manufacturing method.

[0007]

According to the present invention, there is provided a method for manufacturing a wireless suspension blank, comprising a three-layer structure in which a metal layer exhibiting spring characteristics and a conductive layer are interposed via an electrically insulating layer of a polyimide resin. A method for manufacturing a wireless suspension blank using a laminate having a structure, wherein the insulating layer uses a laminate composed of a core insulating layer and an adhesive material layer laminated on both surfaces thereof, Inspecting the adhesive strength of each layer, processing the metal layer, processing the conductive layer to form a wiring portion, and processing the insulating layer by wet etching. .

Further, a metal layer exhibiting a spring characteristic;
Inspecting the adhesive strength between the insulating layer and the conductive layer in the step of inspecting the adhesive strength of each layer of the three-layer structure in which the conductive layer is laminated via the electrical insulating layer made of a polyimide resin. It is characterized by.

Further, a metal layer exhibiting spring characteristics;
In the step of inspecting the adhesive strength of each layer of the three-layer laminated body in which the conductive layer is laminated via the electrical insulating layer which is a polyimide resin, the inspection is performed by peeling the insulating layer and the conductive layer. It is characterized by doing.

[0010] Further, a metal layer exhibiting spring characteristics;
In the step of examining the adhesive strength of each layer of the three-layered laminate in which the conductive layers are laminated via the electrical insulating layer made of a polyimide resin, the adhesive strength between the insulating layer and the conductive layer is set to 0. It is characterized in that it is determined to be non-defective when it is 6 kgf / cm or more.

[0011] Further, in the step of inspecting the adhesive strength of each layer of a three-layer laminated body in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin, The width of the conductive layer to be separated is set to 0.2 mm or less.

In a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrical insulating layer of a polyimide resin, the conductive layer is made of a copper material or a copper alloy. In the step of inspecting the adhesive strength of each layer of the three-layered structure, after peeling the insulating layer and the conductive layer, if the surface of the conductive layer has a reddish color, it is determined to be non-defective. It is characterized by the following.

In a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrical insulating layer of a polyimide resin, the conductive layer is made of a copper material or a copper alloy. In the step of inspecting the adhesive strength of each layer of the three-layer structure, after peeling the insulating layer and the conductive layer, the surface of the conductive layer is reddish color, the insulating layer and the Adhesion strength with conductive layer is 0.6kgf / cm
It is characterized in that it is determined to be a non-defective product when the above is satisfied.

Further, a metal layer exhibiting spring characteristics;
In the step of inspecting the adhesive strength of each layer of the three-layered laminate in which the conductive layers are laminated via the electrically insulating layer of a polyimide resin, the width of the conductive layer to be peeled is set to 0.2 mm or less. It is characterized by.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 relates to an embodiment of the present invention.
Basic manufacturing of a method of manufacturing a wireless suspension blank using a three-layered laminated body in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin. It is explanatory drawing of a flow.

Step 1 (S1) is an inspection step of the laminate having the three-layer structure. Step 2 (S2) is a step of processing a metal layer that exhibits spring characteristics. Step 3 (S3) is a step of processing a conductive layer to be an electric wiring portion of the suspension. Step 4 (S4) is a step of processing an electrical insulating layer made of a polyimide resin. Step 5 (S5) is a conductive layer plating step of plating the conductive layer. Step 6 (S6) is a surface treatment step for protecting the wiring portion and the like.

In step 1 (S1), a step of inspecting the adhesive strength of a three-layered laminated body in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin. It is. In step 2 (S2), a metal layer such as stainless steel (hereinafter abbreviated as SUS) that exhibits spring characteristics is processed by wet etching as the metal layer in the laminate. In step 3 (S3), a conductive layer such as copper (hereinafter abbreviated as Cu) or a copper alloy, which is to be an electric wiring portion of the suspension, is processed as a conductive layer in the laminate by wet etching. Here, step 3 may be processed by changing the order of step 2. Step 4 (S4) is a step of forming a resist image for processing an electrical insulating layer, which is a polyimide resin, and then processing the insulating layer by wet etching according to the resist image. Basically, these four steps make a wireless suspension blank. In step 5 (S5), Au (gold) plating is applied to Cu serving as an electric wiring portion to prevent corrosion of Cu. In step 6 (S6),
A protective layer is formed on the wiring portion formed in step 3 in order to prevent an accident such as an electrical short circuit caused by contact with any conductive material or an external force applied to the wiring portion to damage or break the wiring portion. This is a surface treatment step. In particular, it is preferable to perform the process immediately after processing the conductive layer.

FIG. 2 is a diagram showing the manufacturing flow of S1 to S6 of the method for manufacturing a wireless suspension blank for an HDD according to the embodiment of the present invention.

FIG. 2A shows a laminate for forming a wireless suspension blank for an HDD. This laminate has a metal layer 1 exhibiting spring characteristics.
SUS (stainless steel) having a thickness of 20 μm that exhibits spring characteristics is used, the insulating layer 2 is formed using a 18.0 μm-thick polyimide, and the conductive layer 3 is formed using a 18 μm-thick copper alloy. And the insulating layer is composed of 1
1. A core insulating layer having a thickness of 2.5 μm and formed on both surfaces thereof
It is composed of an adhesive material layer having a thickness of 75 μm. Then, a metal layer 1 and an insulating layer 2 are respectively formed on both sides of the insulating layer via the adhesive material layer.

After receiving such a laminate as a sheet, a sampling inspection is performed. Needless to say, the edge of the sheet-like laminate may be cut and the whole product may be inspected. here,
The inspection in the manufacturing flow of FIG. 2 will be described in detail.

FIG. 4 shows an embodiment of the present invention.
FIG. 9 is an explanatory diagram illustrating an experiment for performing a peeling test between the insulating layer 2 and the conductive layer 3 in a basic manufacturing flow of the wireless suspension blank. That is, the conductive layer 3 is processed into a predetermined line width. Thereafter, the conductive layer 3 having a predetermined line width in a direction perpendicular to the insulating layer 2 is pulled. While maintaining the angle of 90 ° between the direction in which the conductive layer 3 having the predetermined line width is peeled off and the insulating layer 2, the adhesive strength between the conductive layer 3 and the insulating layer 2 is measured. A pass / fail judgment is made according to this measurement result. This is referred to as a first peeling inspection.

Here, of the wireless suspension blanks manufactured using the sheet-like laminate,
The adhesive strength between the conductive layer 3 and the insulating layer 2 was determined by using a sheet-like laminate manufactured under the same conditions as a defective product in which the wiring portion obtained by patterning the conductive layer 3 on the insulating layer 2 was peeled off and a non-defective product that did not peel. measure. First, the conductive layer is divided into a plurality of regions in the sheet-like laminate, and a predetermined line width of 0.05 mm is used.
0.10mm, 0.20mm, 0.50mm, 1.00
mm, 1.50 mm, 2.00 mm, 2.50 mm,
Nine patterns were processed at 3.00 mm to measure the adhesive strength. Depending on the material, the narrower the line width,
The adhesive strength (also called peel strength) decreased, and the tendency became almost constant at 0.2 mm or less. This may be due to the effect of the thickness of the conductive layer, but a clear causal relationship is unknown.

FIG. 5 shows the result. Here, FIG.
Adhesive strength (unit: kgf / cm) and width of conductive layer (unit:
cm). Graph 11 which is a measurement result of a good product
Has an adhesive strength of 0.6 kgf / cm or more even if the line width of the conductive layer is small. However, the graph 12 which is a measurement result of a defective product shows that when the line width of the conductive layer becomes small, 0.6 kg is obtained.
It shows an adhesive strength of f / cm or less. Of course, when the line width of the conductive layer (2.00 mm or the like) is large, 0.6 kgf /
It is needless to say that a product having an adhesive strength of not more than 1 cm is a defective product. Therefore, it was found from this experiment that the adhesive strength was measured by measuring at a line width as small as possible, and the quality of the laminated body could be determined based on the measurement result. When the line width was 0.2 mm or less (judgment line 13) and the adhesive strength was 0.6 kgf / cm (judgment line 14) or more, it was found that the manufactured suspension blank could be judged to be good. This has enabled the first peeling inspection. Line width 0.2mm (Judgment line 1
3) Since the following is substantially parallel, the peeling inspection can be performed with a line width of 0.2 mm.

Next, the laminate shown in FIG. 6 will be described. FIG.
Is a three-layer laminate in which a metal layer 1 exhibiting spring characteristics and a conductive layer 3 are laminated via an electrical insulating layer 2 which is a polyimide resin. The insulating layer 2 includes a core insulating layer 21 and an adhesive material layer 22 laminated on both sides thereof,
23 is an insulating layer 2 composed of Further, the conductive layer 3
Is a conductive layer 3 having a rolled copper layer 31 and a pure copper layer 32 obtained by plating pure copper on the insulating layer 2 side of the rolled copper layer 31 and then matting the pure copper surface. Due to the mat treatment, the adhesive strength with the adhesive material layer 23 is improved.

Using this laminate, the conductive layer 3 is processed to a predetermined line width in the same manner as in FIG. Thereafter, the conductive layer 3 having a predetermined line width in a direction perpendicular to the insulating layer 2 is pulled. The direction in which the conductive layer 3 having a predetermined line width is peeled and the insulating layer 2 are 9
While maintaining the angle of 0 °, the adhesive strength between the conductive layer 3 and the insulating layer 2 is determined based on the color of the conductive layer 3 that has been pulled and peeled off. This is referred to as a second peeling inspection.

First, an experiment was conducted using a defective product in which the wiring portion obtained by patterning the conductive layer 3 on the insulating layer 2 was peeled off, and a sheet-like laminate manufactured under the same conditions as a non-defective product that did not peel off. That is, the sheet-like laminate is divided into a plurality of regions by dividing the conductive layer into a predetermined line width of 0.05 mm and 0.1 mm.
0mm, 0.20mm, 0.50mm, 1.00mm,
1.50 mm, 2.00 mm, 2.50 mm, 3.00
An experiment was conducted by processing 9 patterns as mm 2.

As a result, it was found that the defective product having a low adhesive strength was characterized in that the Cu surface on the adhesive surface side after peeling was brown. In addition, a good product having a high adhesive strength was found to be characterized in that the Cu surface on the adhesive surface side after peeling was red. This is presumed that the color of the Cu surface changes as the oxidation state of the Cu surface changes. That is, it is presumed that the Cu surface becomes brown as the oxidation proceeds, and the adhesive strength is reduced due to the peeling at the oxide layer.
Therefore, it was found that the quality of the laminate can be determined based on the color when the conductive layer was peeled off. That is,
The color indicating the adhesive strength was measured at a position where the line width was as small as possible, and the color indicating the adhesive strength was visually checked or measured by image processing or the like, and it was found that the quality of the laminate could be determined based on the result. If the suspension blank had a reddish color, the manufactured suspension blank was determined to be good. Thus, the second peeling inspection can be performed.

Peeling by a method of manufacturing a wireless suspension blank using a three-layered laminated body in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin. As the inspection, a first peeling inspection may be performed, or a second peeling inspection may be performed. Of course, both may be performed. Subsequently, the description returns to the manufacturing flow of FIG.

FIG. 2B shows an acrylic dry film resist, which is a photosensitive material, laminated on both surfaces of the metal layer 1 and the conductive layer 3 and then exposing and developing the resist according to a predetermined photomask pattern. Thus, a predetermined resist pattern 4 was formed. A specific example is Asahi Kasei A
Laminate Q-5038 at 100 ° C. Exposure is performed with g-line at an exposure amount of 30 to 60 mJ / cm2.
Spray-developed with 0 ° C, 1 wt% Na2CO3. A dry film resist has an advantage that it can be easily obtained and used because the thickness of the resist is fixed. A liquid resist may be used instead of the dry film resist used here. For example, when a casein resist is used, the casein resist can be developed with water, so that there is an advantage that the casein resist can be produced at a lower cost than a dry film resist.

FIG. 2 (c) shows a state in which the metal layer 1 and the conductive layer 3 are wet-etched simultaneously on both sides using a general etching solution of iron chloride, and the metal layer 1 and the conductive layer 3 are processed. Is shown. In this case, the metal layer 1 and the conductive layer 3 may be wet-etched one by one by a single-side lapping method. Here, when wet etching is performed on each side, there is an effect that the cross-sectional shape of the metal layer 1 and the conductive layer 3 that have been wet-etched is finished finely, and when wet etching is performed simultaneously on both sides, the processing time can be shortened. is there.

FIG. 2D shows a state in which the resist pattern 4 has been stripped with a stripping solution composed of sodium hydroxide. 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 polyimide as the insulating layer 2 is obtained.

FIG. 2E shows that the insulating layer 2 is processed by wet etching in a state where the metal layer 1 and the conductive layer 3 formed on both surfaces of the insulating layer 2 are patterned. Therefore, the insulating layer 2 is provided on both the upper surface of the insulating layer 2 on which the patterned conductive layer 3 is processed and the wiring portion is formed, and the lower surface of the insulating layer 2 of the patterned metal layer 1. An insulating layer processing resist is formed in a region to be left. At this time, the insulating layer processing resist pattern 5 is formed so as to overlap the metal layer 1 and the conductive layer 3 patterned on the insulating layer 2. If an insulating layer processing resist pattern 5 is formed only in a region where the insulating layer 2 is left so as not to overlap.
Is formed, there is a possibility that a wet etching solution enters through a gap between the pattern 5 and the metal layer 1 or the conductive layer 3 and the portion of the insulating layer 2 that is not desired to be processed is etched. To prevent this, the insulating layer processing resist pattern 5 is formed on the insulating layer 2 so as to overlap with the patterned metal layer 1 and conductive layer 3. In particular, when the line width of the conductive layer 3 is narrow, if the etching liquid is sprayed during wet etching, the conductive layer having a narrow line width may be peeled off due to the spray pressure of the spray. For this reason, forming the insulating layer processing resist pattern 5 on the conductive layer having a small line width is effective also in such a point.

In order to form the insulating layer processing resist pattern 5, the insulating layer processing resist is formed on both surfaces of the insulating layer 2 by using a dip coating method, a roll coating method, a die coating method or a laminating method. Then, exposure and development are performed according to a predetermined photomask pattern. As a specific example, Asahi Kasei's AQ-3 is used as an insulating layer processing resist.
No. 058 is laminated on both sides of the insulating layer 2 at 100 ° C. Exposure is performed at 30 to 60 mJ / cm 2 with g-line exposure at 30 ° C., 1 wt% Na 2 CO 3.
3. Spray develop with 3. Thus, the insulating layer processing resist pattern 5 is formed so as to overlap the metal layer 1 and the conductive layer 3 patterned on the insulating layer 2.
Further, the insulating layer processing resist may be formed by a printing method instead of the resist exposure / development method.

In FIG. 2F, the insulating layer is processed by performing wet etching with an etching solution of TPE-3000 manufactured by Toray Engineering Co., Ltd. (an alkaline-based polyimide etching solution containing amine). 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.

In FIG. 2G, the insulating layer processing resist pattern 5 used as a mask material for wet etching is peeled off, and the processing of the insulating material is completed. As a specific example of the peeling at this time, peeling with a high-temperature alkaline solution of 50 ° C. and 30 wt% of sodium hydroxide is generally performed. However, when the insulating layer such as polyimide 2 or the like has poor alkali resistance, ethanolamine is used. It is better to use an organic alkali such as

As shown in FIG. 3, gold plating 6 is applied to the conductive layer 3 which is the wiring portion of the wireless suspension blank for HDD formed by the above method, as a finish of processing. The gold plating here was performed in a cyan gold plating bath manufactured by Japan High Purity Chemical. 6 using Temper resist Ex
A current was applied at a current density Dk of 0.4 A / dm 2 for about 4 minutes at 5 ° C. to form a 1 μm thick film. The same result is obtained with acid gold instead of cyan gold. This 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 is not limited to Au plating. Also, Ni / A
u plating may be used, or solder plating or printing may be used instead. Here, in the case of performing Ni plating, a gloss bath, a matte bath, or a semi-gloss bath can be selected. However, a current density Dk = 5 A / dm 2 at 50 ° C. using a solution for a Watt bath manufactured by Japan High Purity Chemical Co., Ltd. For about 1 minute to form a film having a thickness of 1 μm. Then, an epoxy-based cover layer 7 is formed as a protective layer at a necessary portion of the wiring portion.

Thus, the manufacture of the HDD wireless suspension blank is completed. Thereafter, although not shown, mechanical processing of the suspension and assembly processing such as connection of a slider including a magnetoresistive sensor and an inductive writing transducer are finally performed to complete a wireless suspension for the HDD. With the configuration as shown in FIG. 3, if necessary, an electrical inspection such as an operation check of the slider can be performed by using the electrical inspection terminal 8 from the metal layer 1 side of FIG. High quality suspension can be obtained.

[0039]

According to the method of manufacturing a wireless suspension blank including a step of inspecting the received laminate and a step of processing an insulating layer or the like by wet etching, a high-quality and low-cost wireless suspension blank can be manufactured. Was.

[Brief description of the drawings]

FIG. 1 is a view showing a basic processing flow of a laminate according to an embodiment of the present invention.

FIG. 2 is a view showing a processing flow of the laminated body according to the embodiment of the present invention.

FIG. 3 is a diagram showing a laminate according to the embodiment of the present invention.

FIG. 4 is a diagram showing a peeled state of the laminate according to the embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between an adhesive strength at the time of peeling of a laminate according to an embodiment of the present invention and a line width of a conductive layer.

FIG. 6 is a diagram illustrating peeling of a laminate according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal layer 2 ... Insulating layer 3 ... Conductive layer 4 ... Dry film resist pattern 5 ... Insulating layer processing resist pattern 6 ... Gold plating 7 ... Cover layer 8 ... Terminal for electrical inspection

Continued on the front page (72) Inventor Kazuo Umeda 1-1-1, Ichigaya Kagacho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd. (72) Inventor Ken Sasaki 1-1-1, Ichigaga-cho, Shinjuku-ku, Tokyo F term in Dai Nippon Printing Co., Ltd. (reference) 5D042 NA01 PA10 TA07 5D059 AA01 BA01 CA03 DA31 DA33 DA36 EA08

Claims (8)

[Claims] 1. A method of manufacturing a wireless suspension blank using a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin. A step of inspecting the adhesive strength of each layer of the laminate, wherein the insulating layer comprises a core insulating layer and an adhesive material layer laminated on both surfaces thereof, and processing the metal layer. Forming a wiring portion by processing the conductive layer, and processing the insulating layer by wet etching. 2. The step of inspecting the adhesive strength of each layer of a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin. The method for manufacturing a wireless suspension blank according to claim 1, wherein an adhesive strength between an insulating layer and the conductive layer is inspected. 3. A step of inspecting the adhesive strength of each layer of a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin, The method for manufacturing a wireless suspension blank according to claim 1, wherein the inspection is performed by peeling the insulating layer and the conductive layer. 4. A step of inspecting the adhesive strength of each layer of a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin, 0.6 kg of adhesive strength between the insulating layer and the conductive layer
4. The method for manufacturing a wireless suspension blank according to claim 1, wherein a non-defective product is determined when f / cm or more. 5. A step of inspecting the adhesive strength of each layer of a three-layer laminated body in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin, 5. The method for manufacturing a wireless suspension blank according to claim 3, wherein the width of the conductive layer to be peeled is set to 0.2 mm or less. 6. A three-layered structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrical insulating layer made of a polyimide resin, wherein the conductive layer is made of a copper material or a copper alloy. In the step of inspecting the adhesive strength of each layer of the three-layered structure, after peeling the insulating layer and the conductive layer, if the surface of the conductive layer has a reddish color, it is determined to be non-defective. The method for manufacturing a wireless suspension blank according to claim 3, wherein: 7. A three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrical insulating layer made of a polyimide resin, wherein the conductive layer is made of a copper material or a copper alloy. In the step of inspecting the adhesive strength of each layer of the three-layer structure, after peeling the insulating layer and the conductive layer, the surface of the conductive layer is reddish color, the insulating layer and the 4. A non-defective product when the adhesive strength with the conductive layer is 0.6 kgf / cm or more.
A method for producing the wireless suspension blank according to the above. 8. A step of inspecting the adhesive strength of each layer of a three-layer structure in which a conductive layer is laminated via a metal layer exhibiting spring characteristics and an electrically insulating layer made of a polyimide resin, The method for manufacturing a wireless suspension blank according to claim 7, wherein the width of the conductive layer to be peeled is set to 0.2 mm or less.