JP4992648B2 - Suspension board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a suspension board used for a hard disk drive (HDD) or the like, and more particularly to a suspension board that can maintain the electrical characteristics of a ground layer and has low rigidity.

  In recent years, due to the spread of the Internet and the like, there has been a demand for an increase in the amount of information processing of personal computers and an increase in information processing speed, and along with this, the capacity of hard disk drives (HDD) incorporated in personal computers has increased. Increasing information transmission speed is required. In addition, a component called a magnetic head suspension that supports the magnetic head used in the HDD also has a signal line such as a copper wiring directly formed on a stainless steel spring from a conventional type in which a signal line such as a gold wire is connected. The so-called wireless suspension has been shifted to a wiring integrated type (flexure).

  In recent years, there has been a tendency for higher frequency electrical signals to be used to improve the signal transmission speed and accuracy of HDDs, but there has been a problem that the signal strength attenuation rate (transmission loss) increases as the frequency increases. . This is considered to be caused by low conductivity of SUS or the like generally used as a metal support substrate. For such a problem, for example, Patent Document 1 discloses a printed circuit board in which a metal thin film and a metal foil are disposed between a metal support substrate and an insulating layer. Patent Document 2 discloses a printed circuit board in which a metal foil having a through hole is disposed between a metal supporting board and an insulating layer. These have reduced conduction loss by disposing a metal foil or the like having good conductivity between the metal support substrate and the insulating layer.

  However, when these metal foils are installed, there is a problem that the rigidity of the suspension board is increased. In addition, the above patent document discloses disposing a ground layer such as a metal foil between the metal support substrate and the ground layer, but also describes a preferable disposition method in terms of electrical characteristics. It was not done.

The wiring pattern provided on the suspension board is usually formed by arranging a recording wiring pair and a reproducing wiring pair in the same plane as in the slider / suspension device described in Patent Document 3, for example. Is. For example, as described in Patent Document 4, a wiring pattern (conductor circuit), a cover layer (coverage), a terminal, and the like are formed on the insulating layer (see FIG. 1 of Patent Document 4). .
JP 2006-245220 A JP 2006-278734 A JP 2005-11387 A Japanese Patent No. 3226489

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a suspension board that can maintain the electrical characteristics of the ground layer and has low rigidity.

  In order to solve the above problems, in the present invention, a metal support substrate, a ground layer formed on the metal support substrate and having higher conductivity than the metal support substrate, the metal support layer, and the ground layer A suspension board having an insulating layer formed thereon and a wiring pattern formed on the insulating layer and composed of a wiring pair, from the tip of the suspension board on the side where the gimbal portion is formed, A suspension board is provided in which an average distance between an end portion of the wiring pair and an end portion of the ground layer is in a range of 50 μm to 100 μm in a region up to a portion immediately before the tail portion.

  According to the present invention, by designing the average distance between the end of the wiring pair and the end of the ground layer to be within the above range, the same as when the ground layer is formed on the entire surface of the metal support substrate. The suspension board can exhibit the above electrical characteristics and has low rigidity.

  In the said invention, it is preferable that the adhesive improvement layer is formed between the said ground layer and the said metal support substrate. This is because the adhesion between the ground layer and the metal support substrate can be further improved.

  In the said invention, it is preferable that the diffusion prevention layer which prevents that the material of the said ground layer diffuses into the said insulating layer is formed between the said ground layer and the said insulating layer. For example, when the material of the ground layer is copper and the material of the insulating layer is polyimide, copper diffuses into the polyimide, and adhesion between the ground layer and the insulating layer may be reduced. In addition, copper migrates into the polyimide in an environmental test, which may impair reliability. For this reason, it is preferable to provide a diffusion preventing layer from the viewpoints of suppressing adhesion deterioration and improving reliability.

  In the said invention, it is preferable that the said metal support substrate has a recessed part and the said ground layer is formed in the said recessed part. This is because the adhesion between the ground layer and the metal support substrate can be improved by embedding the ground layer in the concave portion of the metal support substrate.

  In the present invention, a ground layer forming step of forming a ground layer having a higher conductivity than the metal support substrate on the metal support substrate, and forming an insulating layer on the metal support substrate and the ground layer. Forming an insulating layer and a wiring pattern composed of a wiring pair on the insulating layer at a position where an average distance between an end of the wiring pair and an end of the ground layer falls within a range of 50 μm to 100 μm And a wiring pattern forming step to provide a suspension board manufacturing method.

  According to the present invention, by designing the average distance between the end of the wiring pair and the end of the ground layer to be within the above range, the suspension that maintains the electrical characteristics of the ground layer and has low rigidity. A substrate can be obtained.

  In the present invention, there is an effect that it is possible to obtain a suspension board that can maintain the electrical characteristics of the ground layer and has low rigidity.

  Hereinafter, the suspension board and the manufacturing method thereof according to the present invention will be described in detail.

A. Suspension board First, the suspension board of the present invention will be described. The suspension board of the present invention includes a metal support board, a ground layer formed on the metal support board and having a higher conductivity than the metal support board, and an insulation formed on the metal support layer and the ground layer. A suspension board having a layer and a wiring pattern formed on the insulating layer, the wiring pattern including a wiring pair, and a portion immediately before the tail portion from the tip of the suspension board on the side where the gimbal portion is formed The average distance between the end portion of the wiring pair and the end portion of the ground layer is in the range of 50 μm to 100 μm.

  In the present invention, the “end portion of the wiring pair” means an end portion of the wiring pair that is an edge portion of the wiring pair pattern. The “end portion of the ground layer” means an end portion of the ground layer that is an edge portion of the ground layer region.

  According to the present invention, by designing the average distance between the end of the wiring pair and the end of the ground layer to be within the above range, the same as when the ground layer is formed on the entire surface of the metal support substrate. The suspension board can exhibit the above battery characteristics and has low rigidity. Conventionally, it has been known that a ground layer such as a metal foil is disposed between the metal support substrate and the insulating layer. However, the rigidity of the suspension substrate may be increased by arranging the metal foil or the like. . On the other hand, in the present invention, by performing patterning of the ground layer within a range that does not impair the electrical characteristics of the ground layer, a suspension board that maintains the electrical characteristics of the ground layer and has low rigidity can be obtained. it can. In other words, the rigidity of the suspension board is reduced by eliminating the ground layer that is unnecessary in terms of electrical characteristics.

  Further, according to the present invention, since the ground layer has a higher conductivity than the metal support substrate, it is possible to suppress a reduction in transmission loss. The suspension board of the present invention can be used for a magnetic head suspension of a hard disk drive (HDD), for example.

  Next, the suspension board of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the suspension board of the present invention. The suspension board shown in FIG. 1 is a metal support board 1 made of SUS, a ground layer 2 (2A, 2B) made of copper having a higher conductivity than the metal support board 1 and formed on the metal support board 1. An insulating layer 3 made of polyimide (PI) formed on the metal support substrate 1 and the ground layer 2, and a wiring pair 4A (for example, a recording wiring pair) and a wiring pair 4B formed on the insulating layer 3 and made of copper. And a wiring pattern having (for example, a wiring pair for reproduction).

Furthermore, in the present invention, for the distance W _a between the end of the wiring 4a in the wiring pair 4A and the end of the ground layer 2A, and the distances W _{b to} W _d defined in the same way, these average distances are: It is characterized by being within a specific range. As a result, the electrical characteristics of the ground layer can be maintained, and the rigidity of the suspension board can be reduced. In the present invention, the values of W _{a to} W _d may be the same or different from each other.

In the present invention, the distance between the two wire pairs is sometimes widened and sometimes narrowed according to the shape of the suspension board. As shown in FIG. 1, when the distance between the wiring pair 4A and the wiring pair 4B is sufficiently large, the end portion of the ground layer 2 is formed between the wiring pair 4A and the wiring pair 4B. On the other hand, as shown in FIG. 2, when the distance between the wiring pair 4A and the wiring pair 4B is short, the end of the ground layer 2 is not formed between the wiring pair 4A and the wiring pair 4B. In this case, the average of W _a and W _d in FIG. 2 needs to be within a specific range. Note that if the distance between the two wire pairs is shorter than the distance obtained by doubling the average distance described above, an overlap may occur, and the end portion of the ground layer may not be formed between the wire pairs.

  In the present invention, as shown in FIG. 3, an adhesion improving layer 5 may be formed between the ground layer 2 (2A, 2B) and the metal supporting substrate 1, and the ground layer 2 (2A 2B) and the insulating layer 3 may be provided with a diffusion preventing layer 6 for preventing the material of the ground layer 2 from diffusing into the insulating layer 3.

  FIG. 4 is a schematic plan view illustrating the entire image of the suspension board of the present invention, and the cover layer is omitted for convenience. The suspension board shown in FIG. 4 has a structure in which a metal support board (not shown), a ground layer (not shown), and an insulating layer 3 are laminated, and a magnetic head is provided at one end of the suspension board. A gimbal portion 11 for mounting the external connection terminal region 12 is formed at the other end, and an external connection terminal region 12 for connection to an external circuit is formed. Wiring for connecting the gimbal portion 11 and the external connection terminal region 12 Patterns (wirings 4a to 4d) are formed.

  In the present invention, the average distance between the end of the wiring pair and the end of the ground layer is measured in the “region from the tip of the suspension board on the side where the gimbal is formed to the portion immediately before the tail”. To do. Specifically, as shown in FIG. 4, this region refers to a region from the tip A1 of the suspension board on the side where the gimbal portion 11 is formed to the portion A2 immediately before the tail portion. Note that the tail portion usually refers to a portion where a wire pair composed of two wires branches toward each external connection terminal.

  Further, in the present invention, in the region from the tip of the suspension board on the side where the gimbal part is formed to the portion of 80% of the total length of the suspension board, the end of the wiring pair and the end of the ground layer The average distance may be measured. Specifically, as shown in FIG. 4, this region refers to a region from the tip A1 of the suspension board on the side where the gimbal portion 11 is formed to a portion that is 80% of the total length A3 of the suspension board.

In the present invention, the “average distance between the end of the wiring pair and the end of the ground layer” means the average distance in the horizontal direction between the end of the wiring pair and the end of the ground layer corresponding to the end. Say. Specifically, it means the average of the distances represented by W _{a to} W _d in FIG. As shown in FIG. 2 described above, when the distance between the wiring pair 4A and the wiring pair 4B is short and the end portion of the ground layer 2 is not formed between the wiring pair 4A and the wiring pair 4B, W _a and W _d The average of the distance represented by

In the present invention, the average distance between the end of the wiring pair and the end of the ground layer is usually calculated by the following method. That is, when the suspension board is observed from the plane direction, the area of the region specified by the distances W _{a to} W _d in FIG. 1 described above (the region of the ground layer outside the end of the wiring in plan view) is determined. The calculation is performed by calculating the respective values and averaging the values obtained by dividing the respective area values by the lengths of the end portions of the corresponding wirings 4a to 4d. The above area and length can be accurately calculated by using, for example, an image processing technique.

In the present invention, the average distance between the end of the wiring pair and the end of the ground layer can be approximately calculated by the following method. That is, the suspension board is observed from the plane direction, and as shown in FIG. 5, the region from the tip A1 of the suspension board on the side where the gimbal part 11 is formed to the part A2 just before the tail part is equally divided into ten. In the portions I to X, the distances W _{a to} W _d in FIG. 1 described above can be calculated by measuring and averaging the distances W _{a to} W _d in the direction perpendicular to the wiring.
Hereinafter, the suspension board of the present invention will be described separately for the members of the suspension board and the configuration of the suspension board.

1. First, the suspension board member of the present invention will be described. The suspension board of the present invention has at least a metal support board, a ground layer, an insulating layer, and a wiring pattern. Furthermore, if necessary, an adhesion improving layer may be provided between the ground layer and the metal supporting substrate, and a diffusion preventing layer may be provided between the ground layer and the insulating layer.

(1) Metal support substrate First, the metal support substrate used for this invention is demonstrated. The metal support substrate used in the present invention usually has an appropriate spring property. The material for the metal support substrate is not particularly limited as long as it has springiness and conductivity, and examples thereof include SUS, 42 alloy, copper, copper alloy, etc. Among them, SUS is preferable. . The thickness of the metal support substrate is, for example, in the range of 12 μm to 76 μm, and preferably in the range of 14 μm to 25 μm.

(2) Ground Layer Next, the ground layer used in the present invention will be described. The ground layer used in the present invention has high conductivity, is formed on a metal support substrate, and has higher conductivity than the metal support substrate. When the electrical conductivity of the ground layer is represented by the specific resistance which is the reciprocal thereof, it is not particularly limited. For example, it is preferably 100 × 10 ⁻⁸ Ωm or less, and 1.0 × 10 ⁻⁸ Ωm to 60 more preferably in the range of × ^{10 -8} Ωm, and particularly preferably in the range of ^{1.5 × 10 -8 Ωm~10 × 10 -8} Ωm.

  The material of the ground layer is not particularly limited as long as it has a higher conductivity than the material of the metal support substrate used. Examples thereof include copper, nickel, gold, silver, and aluminum. Among them, copper is preferable. This is because it has high conductivity and is inexpensive.

  The average thickness of the ground layer is not particularly limited, but is, for example, in the range of 0.1 μm to 10 μm, in particular in the range of 0.2 μm to 8 μm, particularly in the range of 0.5 μm to 6 μm. It is preferable. The average thickness can be measured with a fluorescent X-ray measuring machine, a laser microscope measuring machine, a contact-type thickness measuring machine, or a three-dimensional measuring machine. The method for forming the ground layer will be described in detail in “B. Suspension board manufacturing method” described later.

  In the present invention, an adhesion improving layer is preferably formed between the ground layer and the metal support substrate. This is because the adhesion between the ground layer and the metal support substrate can be further improved. Further, for example, when the material of the ground layer is copper and the material of the metal support substrate is SUS, copper diffuses into the SUS, and the adhesion between the ground layer and the metal support substrate may be reduced. The adhesion improving layer can prevent this, and also has a diffusion preventing function.

  Examples of the material for the adhesion improving layer include Ni, Cr, Ti, Au, Ag, Zn, Mo, W, V, Co, and alloys, oxides, and nitrides thereof. Of these, Ni, Cr, Ti, and alloys, oxides and nitrides thereof are preferable.

  The thickness of the adhesion improving layer is not particularly limited, but for example, within the range of 0.001 μm to 5 μm, particularly within the range of 0.005 μm to 3 μm, and particularly within the range of 0.01 μm to 2 μm. Preferably there is. Examples of the method for forming the adhesion improving layer include plating methods such as an electrolytic plating method and an electroless plating method, a sputtering method, a vapor deposition method, etc. Among them, the plating method and the sputtering method are preferable. The electrolytic plating method is more preferable. In particular, in the present invention, the adhesion improving layer is preferably formed by a Ni strike plating method.

  In the present invention, it is preferable that a diffusion preventing layer for preventing the material of the ground layer from diffusing into the insulating layer is formed between the ground layer and the insulating layer. For example, when the material of the ground layer is copper and the material of the insulating layer is polyimide, copper diffuses into the polyimide, and adhesion between the ground layer and the insulating layer may be reduced. Therefore, it is preferable to provide an anti-diffusion layer from the viewpoint of suppressing adhesion deterioration.

  The kind of the diffusion preventing layer is not particularly limited as long as the material of the ground layer can be prevented from diffusing, and examples thereof include an organic film and an inorganic film. As said organic membrane | film | coat, a rust prevention membrane | film | coat by the processing liquid containing a diazole, a triazole, tetrazole, and those derivatives can be mentioned, for example, Among others, Imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4 -Methylimidazole, 2-phenylimidazole, 2-undecylimidazole, benzimidazole and the like are preferable. Examples of the inorganic film include a Cr film, a Ni film, a Zn film, a Ti film, a Mo film, a W film, a V film, a Co film, and an alloy film thereof, among which a Ni film and a Cr film. And their alloy films are preferred.

  The thickness of the diffusion preventing layer is not particularly limited, but is, for example, in the range of 0.001 μm to 5 μm, particularly in the range of 0.005 μm to 3 μm, particularly in the range of 0.01 μm to 2 μm. It is preferable. Moreover, as a method of forming the said diffusion prevention layer, when forming an organic membrane, the method of forming by the dipping process and the spray process with the liquid containing the said azoles etc. can be mentioned, for example. On the other hand, in the case of forming an inorganic film, an electroless plating method, an electrolytic plating method, a sputtering method, a vapor deposition method, and the like can be given.

(3) Insulating layer Next, the insulating layer used in the present invention will be described. The insulating layer used in the present invention is formed on the metal support substrate layer and the ground layer. For example, when the material of the ground layer is copper, deterioration due to oxidation or the like is likely to occur. Therefore, the width of the insulating layer is preferably larger than the width of the ground layer so that the ground layer is not exposed.

  The material for the insulating layer is not particularly limited as long as it has a desired insulating property, and examples thereof include a polyimide resin and a thermoplastic polyimide resin. In particular, in the present invention, the insulating layer is preferably a composite insulating layer made of a polyimide resin and a thermoplastic polyimide resin. The thickness of the insulating layer is, for example, in the range of 5 μm to 20 μm, and preferably in the range of 8 μm to 12 μm.

(4) Wiring pattern Next, the wiring pattern used for this invention is demonstrated. The wiring pattern used in the present invention is formed on the insulating layer and is composed of wiring pairs. The material of the wiring pattern is not particularly limited as long as it has a desired conductivity, and examples thereof include copper, nickel, gold, silver, and aluminum. Among them, copper is preferable. The wiring pattern has a thickness in the range of 5 μm to 15 μm, for example.

  The wire pair usually has two wires. Specifically, as shown in FIG. 1 described above, the wiring pair 4A has two wirings, that is, a wiring 4a and a wiring 4b. The distance between these wirings is not particularly limited, but it is usually preferably in the range of 10 μm to 100 μm, particularly preferably in the range of 15 μm to 90 μm.

  The wiring pattern usually has two wiring pairs, a recording wiring pair and a reproduction wiring pair. Specifically, as shown in FIG. 1 described above, there are two wiring pairs, a wiring pair 4A and a wiring pair 4B. The distance between these wiring pairs is not particularly limited, but is preferably, for example, 200 μm or more, more preferably in the range of 250 μm to 3000 μm, particularly in the range of 300 μm to 2000 μm. This is because crosstalk between wiring pairs can be reduced.

(5) Others The suspension board of the present invention may have a cover layer that covers the wiring pattern, or may have a plating layer that protects the surface of the wiring pattern. Since the cover layer and the plating layer are the same as those used for a general suspension board, description thereof is omitted here.

2. Next, the structure of the suspension board according to the present invention will be described. In the suspension board of the present invention, the average distance between the end of the wiring pair and the end of the ground layer is specified in the region from the tip of the suspension board on the side where the gimbal part is formed to the part immediately before the tail part. One of the characteristics is that it is within the range of.

  In the present invention, the average distance between the end of the wiring pair and the end of the ground layer is usually in the range of 50 μm to 100 μm. The lower limit of the average distance is usually 50 μm, but the average distance is preferably 60 μm or more in consideration of alignment accuracy and the like. On the other hand, the upper limit of the average distance is usually 100 μm, but considering the low rigidity of the suspension board, the average distance is preferably 90 μm or less.

  As shown in FIG. 6, the average distance between the end of the wiring pair and the end of the insulating layer is P, and the average distance between the end of the ground layer and the end of the insulating layer is Q. In the present invention, the value of P varies depending on the structure of the suspension board and the like, but is usually in the range of 10 μm to 400 μm, and preferably in the range of 20 μm to 200 μm. On the other hand, the value of Q is not particularly limited as long as the ground layer does not deteriorate due to oxygen or the like, but is usually 10 μm or more, and preferably in the range of 20 μm to 200 μm. Note that these average distance measurement methods are the same as the above-described average distance measurement method between the end of the wiring pair and the end of the ground layer.

  Moreover, in this invention, it is preferable that a metal support substrate has a recessed part and the ground layer is formed in the said recessed part. This is because the adhesion between the ground layer and the metal support substrate can be improved by embedding the ground layer in the concave portion of the metal support substrate. By improving the adhesion, it is possible to obtain a suspension substrate having excellent substrate reliability in long-term use. In addition, it is thought that the improvement of adhesiveness by providing a recessed part is based on an anchor effect.

  As such a suspension substrate, for example, as shown in FIG. 7, a metal support substrate 1 having a recess and made of SUS, and copper having a conductivity higher than that of the metal support substrate 1 are formed so as to be embedded in the recess. A ground layer 2 (2A, 2B) made of, an insulating layer 3 made of polyimide (PI) formed on the metal support substrate 1 and the ground layer 2, and a wiring pair 4A made of copper formed on the insulating layer 3 (For example, a recording wiring pair) and a wiring pattern having a wiring pair 4B (for example, a reproducing wiring pair).

  When the concave portion is formed in the metal support substrate, if the concave portion is too deep, the mechanical strength of the metal support substrate may be lowered. If the concave portion is too shallow, the ground layer formed in the concave portion is sufficient. There is a possibility that electrical characteristics cannot be exhibited. In the present invention, the depth of the recess is, for example, in the range of 0.05% to 50%, particularly in the range of 0.5% to 40%, particularly 2. It is preferable to be within the range of 5% to 30%. Further, the average depth of the concave portion is not particularly limited, but specifically, it is within a range of 0.01 μm to 10 μm, particularly within a range of 0.1 μm to 8 μm, particularly 0.5 μm to 6 μm. It is preferable to be within the range. The average depth can be measured with a laser microscope measuring machine, a contact-type thickness measuring machine, a three-dimensional measuring machine, or the like.

  In the present invention, the surface roughness of the bottom surface of the recess is preferably large. This is because the anchor effect appears more remarkably and the adhesion between the metal support substrate and the ground layer is further improved. The surface roughness Rz of the bottom surface of the recess is, for example, preferably in the range of 0.1 μm to 10 μm, and more preferably in the range of 0.2 μm to 5 μm. The surface roughness can be measured, for example, with a laser microscope.

  Here, as shown in FIG. 8, let X be the average depth of the recesses of the metal support substrate 1 and Y be the average thickness of the ground layer 2. For convenience, the insulating layer and the like are omitted. In this case, the relationship between X and Y is not particularly limited, X may be large, Y may be large, and X and Y may be the same.

Among them, in the present invention, it is preferable that the difference between X and Y is small. Specifically, the absolute value of XY is preferably 5 μm or less, more preferably 2 μm or less, and particularly preferably 0.5 μm or less. If the difference between X and Y is small, the level difference between the surface of the metal support substrate and the ground layer becomes small, and it is possible to form an insulating layer having excellent flatness and a uniform film thickness, and the impedance can be easily controlled. It is.
The average thickness of the ground layer is the same as that described in the above “(1) Suspension board member”, and the description thereof is omitted here. Further, when the above-described diffusion preventing layer and / or adhesion improving layer is formed on the surface of the ground layer, the total film thickness is considered as Y.

B. Next, a method for manufacturing a suspension board according to the present invention will be described. The suspension board manufacturing method of the present invention includes a ground layer forming step of forming a ground layer having a higher conductivity than the metal support board on the metal support board, and an insulating layer on the metal support board and the ground layer. In the insulating layer forming step of forming the wiring pattern, and the wiring pattern formed of the wiring pair on the insulating layer, the average distance between the end of the wiring pair and the end of the ground layer is in the range of 50 μm to 100 μm. And a wiring pattern forming step formed at the position.

  According to the present invention, by designing the average distance between the end of the wiring pair and the end of the ground layer to be within the above range, the suspension that maintains the electrical characteristics of the ground layer and has low rigidity. A substrate can be obtained.

  Next, a method for manufacturing a suspension board according to the present invention will be described with reference to the drawings. FIG. 9 is a schematic cross-sectional view showing an example of a method for manufacturing a suspension board according to the present invention. In FIG. 9, first, a flat metal support substrate 1 made of SUS is prepared (FIG. 9A), and Ni strike plating is performed on the metal support substrate 1 to form an adhesion improving layer 5. (FIG. 9 (b)), and thereafter forming a ground layer 2 (2A, 2B) made of Cu by electrolytic plating (FIG. 9 (c)), and then immersing in a chemical containing azoles, The anti-diffusion layer 6 made of an organic rust-preventing film containing a kind is formed (FIG. 9D).

Next, an insulating layer 3 made of polyimide is formed on the obtained diffusion prevention layer 6 by a casting method (FIG. 9E). Finally, a wiring board (wirings 4a to 4d and wiring pairs 4A and 4B) is formed on the insulating layer 3 to obtain a suspension board (FIG. 9F). In the present invention, the wiring pair and the ground layer are formed so that the average distance between the end of the wiring pair and the end of the ground layer is within a specific range.
Hereinafter, the method for manufacturing a suspension board of the present invention will be described step by step.

1. Next, the ground layer forming step in the present invention will be described. The ground layer forming step in the present invention is a step of forming a ground layer having a higher conductivity than the metal supporting substrate on the metal supporting substrate. The method for forming the ground layer on the metal supporting substrate is not particularly limited as long as a desired ground layer can be formed. Examples thereof include a plating method, an ink jet method, and a sputtering method.

  Examples of the plating method include an electrolytic plating method and an electroless plating method. Among them, the electrolytic plating method is preferable. Moreover, the said inkjet method can mention the method etc. which apply | coat and sinter the metal nano paste which does not require a plate-making process to a metal support substrate by an inkjet, for example. The formation method of the ground layer may be either an additive method or a subtractive method.

  As a method for forming the ground layer by the additive method, for example, a dry film resist is used to form a resist pattern in a region of the metal support substrate other than the region in which the ground layer is formed, and then the surface of the exposed metal support substrate is electrolyzed. Examples include a method of forming a ground layer by plating or the like, and finally removing the resist pattern.

  As a method for forming the ground layer by the subtractive method, for example, a ground material layer is formed on the entire surface of the metal support substrate, and a resist pattern is formed in a region where the ground layer is formed using a dry film resist or the like. Examples include a method of removing the exposed ground material layer and finally removing the resist pattern.

  In the present invention, it is preferable to perform an adhesion improving layer forming step of forming an adhesion improving layer on the surface of the metal support substrate before the ground layer forming step. This is because the adhesion between the ground layer and the metal support substrate can be further improved. Examples of the method for forming the adhesion improving layer on the metal support substrate include plating methods such as an electrolytic plating method and an electroless plating method; sputtering methods, vapor deposition methods, and the like. Preferably, the electrolytic plating method is more preferable. In particular, in the present invention, it is preferable to perform Ni strike plating.

  In the present invention, it is preferable to perform a diffusion preventing layer forming step of forming a diffusion preventing layer for preventing the material of the ground layer from diffusing into the insulating layer on the ground layer after performing the ground layer forming step. For example, when the material of the ground layer is copper and the material of the insulating layer is polyimide, copper diffuses into the polyimide, and adhesion between the ground layer and the insulating layer may be reduced. In addition, copper migrates into the polyimide in an environmental test, which may impair reliability. For this reason, it is preferable to provide a diffusion preventing layer from the viewpoints of suppressing adhesion deterioration and improving reliability.

  Examples of the method for forming the diffusion preventing layer on the ground layer include a method of immersing in a chemical containing azoles. The ground layer, the adhesion improving layer, the diffusion preventing layer, and the like are the same as the contents described in “A. Suspension board”, and thus the description thereof is omitted here.

2. Insulating layer forming step Next, the insulating layer forming step in the present invention will be described. The insulating layer forming step in the present invention is a step of forming an insulating layer on the metal support substrate and the ground layer. For example, when the material of the ground layer is copper, deterioration due to oxidation or the like is likely to occur. Therefore, the width of the insulating layer is preferably larger than the width of the ground layer so that the ground layer is not exposed.

  The method of forming the insulating layer on the ground layer is not particularly limited. For example, a method of applying a coating solution containing an insulating layer forming resin to the ground layer, and an insulating layer forming resin A method of laminating on the ground layer can be mentioned.

Among these, in the present invention, a method of applying a coating solution containing an insulating layer forming resin to the ground layer is preferable. This is because an insulating layer with good flatness can be obtained. As described above, in the present invention, the ground layer is usually formed on the metal support substrate, and there is a step between the surface of the metal support substrate and the surface of the ground layer. If the viscosity or the like is appropriate, the influence of the step is reduced, and an insulating layer having a flat surface can be formed.
The insulating layer obtained in this step is the same as that described in “A. Suspension substrate”, and thus the description thereof is omitted here.

3. Wiring pattern forming step Next, the wiring pattern forming step in the present invention will be described. In the wiring pattern forming process according to the present invention, a wiring pattern composed of a wiring pair is formed on the insulating layer at a position where the average distance between the end of the wiring pair and the end of the ground layer is in the range of 50 μm to 100 μm. It is a process to do. Note that the preferable range of the average distance is the same as the content described in the above “A. Suspension board”, and thus the description thereof is omitted here.

  The method for forming the wiring pattern on the insulating layer is not particularly limited, and examples thereof include a plating method. Among them, the electrolytic plating method is preferable. Further, the method of forming the wiring pattern may be either an additive method or a subtractive method.

  As a method for forming a wiring pattern by the additive method, for example, a resist pattern opposite to the intended wiring pattern is formed on the insulating layer using a dry film resist or the like, and an electrolytic plating method is applied to the exposed surface of the insulating layer. A method of forming a wiring pattern by the above method and finally removing the resist pattern can be given.

As a method for forming a wiring pattern by the subtractive method, for example, a wiring material layer is formed on the entire surface of the insulating layer, a resist pattern that is the same as the target wiring pattern is formed using a dry film resist or the like, and then exposed. The wiring material layer to be removed can be removed by wet etching or the like, and finally the method of removing the resist pattern can be exemplified.
The wiring pattern obtained in this step is the same as that described in “A. Suspension board”, and the description thereof is omitted here.

4). Others In the present invention, a recess forming step for forming a recess on the surface of the metal support substrate may be performed before the ground layer forming step. By forming a recess on the surface of the metal support substrate, a suspension substrate with excellent adhesion can be obtained. The method for forming the recesses on the surface of the metal support substrate is not particularly limited as long as the desired recesses can be formed. For example, a metal support that is exposed by forming a resist pattern on the metal support substrate is exposed. A method for etching a substrate can be given.

  Examples of a method for forming a resist pattern on a metal support substrate include a method of forming a resist pattern in an unetched region by coating the surface of the metal support substrate with a dry film resist and performing exposure and development. . Further, the resist pattern may be formed by applying and drying a liquid resist.

  The method for etching the metal support substrate is not particularly limited, but a method by wet etching is usually used. It is preferable that the type of the etching solution is appropriately selected according to the material of the metal support substrate. For example, when the material of the metal support substrate is SUS, it is preferable to use an iron chloride etching solution. In the present invention, etching is preferably performed to such an extent that a desired recess can be formed. Since the concave portion of the metal support substrate is the same as the content described in the above “A. Suspension substrate”, description thereof is omitted here.

  The suspension board manufacturing method of the present invention may have a cover layer forming step of forming a cover layer that covers the wiring pattern, and a plating layer that forms a plating layer that protects the surface of the wiring pattern. You may have a formation process.

  Examples of the method for forming the cover layer include a method in which a coating liquid containing a resin for forming a cover layer is applied to a wiring pattern and an insulating layer, dried, and further cured as necessary. Examples of the method for forming the plating layer include an electrolytic plating method and an electroless plating method, and among them, the electrolytic plating method is preferable.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration and exhibits the same function and effect regardless of the case. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described more specifically with reference to examples.
[Example 1]
After the surface of a flat metal support substrate made of SUS having a thickness of 20 μm is treated with 10% hydrochloric acid, an adhesion improvement layer made of 0.2 μm is formed on the entire surface of the metal support substrate by Ni strike plating. A copper ground layer having a thickness of 2 μm was formed on the entire surface of the adhesion improving layer by copper plating (the obtained copper ground layer was used as the entire copper ground layer).
Next, DFR is laminated on the entire surface of the copper ground layer, and exposed and developed with a pattern designed so that the average distance between the end of the wiring pair and the end of the copper ground layer is 50 μm. A resist pattern was formed in the region where the copper ground layer was formed. Thereafter, the exposed entire copper ground layer was removed by wet etching, and then the DFR was peeled off with a sodium hydroxide aqueous solution to form a predetermined copper ground layer.

  Then, after forming an organic rust preventive film on the copper ground layer, a polyamic acid resin was applied to form a 10 μm thick polyimide film. By forming a 9 μm conductor layer on the polyimide film, laminating DFR on the surface, exposing and developing with a pattern in which the average distance between the end of the wiring pair and the end of the copper ground layer is 50 μm, and developing, A resist pattern was prepared in a region where a wiring pair was formed. After the exposed conductor layer was removed by wet etching, the DFR was peeled off from the resist with a sodium hydroxide aqueous solution to form a predetermined wiring pair. Thereafter, a polyamic acid resin was applied to the wiring pair to form a cover layer having a thickness of 4 μm. The terminal part exposed from the cover layer was subjected to gold plating to produce a suspension board.

[Example 2]
A suspension board was manufactured in the same manner as in Example 1 except that the average distance between the wiring pair, the end, and the end of the copper ground layer was 100 μm.

[Comparative Example 1]
A suspension board was fabricated in the same manner as in Example 1 except that the entire copper ground layer was used without etching.

[Comparative Example 2]
Except that the copper ground layer was formed in the opening in accordance with the width of the opening between the wiring pairs (the average distance between the wiring pair, the end, and the end of the copper ground layer was less than 50 μm). A suspension board was produced in the same manner.

[Comparative Example 3]
A suspension board was produced in the same manner as in Example 1 except that the copper ground layer was not formed, a polyimide film was directly formed on the metal supporting board, and a wiring pair was formed.

[Evaluation]
A high frequency signal of 2 GHz was transmitted to the wire pair, and the insertion loss of the signal was measured. The result is shown in FIG.
Example 1: -0.366 dB
Example 2: -0.358 dB
Comparative Example 1: -0.355 dB
Comparative example 2: -0.442 dB
Comparative Example 3: -0.669 dB
If the copper ground layer is formed by setting the average distance between the end of the wiring pair and the end of the copper ground layer to 50 μm to 100 μm, an insertion loss effect almost equivalent to leaving the copper ground layer on the entire surface can be obtained. At the same time, it was confirmed that a suspension board with low rigidity could be produced.

It is a schematic sectional drawing which shows an example of the suspension board of this invention. It is explanatory drawing explaining the shape of a ground layer in case the distance of a wiring pair is near. It is a schematic sectional drawing which shows the other example of the suspension board of this invention. It is a schematic plan view which illustrates the whole image of the suspension board of the present invention. It is explanatory drawing explaining the measuring method of the average distance of the edge part of a wiring pair, and the edge part of the said ground layer. It is a schematic sectional drawing which shows the other example of the suspension board of this invention. It is explanatory drawing explaining the dimension of the suspension board of this invention. It is explanatory drawing explaining the relationship between the depth of the recessed part of a metal support substrate, and the thickness of a ground layer. It is a schematic sectional drawing which shows an example of the manufacturing method of the suspension board of this invention. It is a graph which shows the result of a measurement of insertion loss.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Metal support substrate 2 ... Ground layer 3 ... Insulating layer 4 ... Wiring pattern 5 ... Adhesion improvement layer 6 ... Diffusion prevention layer

Claims (4)

A metal support substrate; a ground layer formed on the metal support substrate and having a higher conductivity than the metal support substrate; an insulating layer formed on the metal support layer and the ground layer; and the insulating layer. A suspension board having a wiring pattern formed of a pair of wirings,
In the region from the tip of the suspension board on the side where the gimbal portion is formed to the portion immediately before the tail portion, the average distance between the end of the wiring pair and the end of the ground layer is 50 μm to 100 μm range in der is,
The suspension board according to claim 1, wherein the metal support substrate has a recess, and the ground layer is formed in the recess .   The suspension board according to claim 1, wherein an adhesion improving layer is formed between the ground layer and the metal supporting board.   The diffusion prevention layer for preventing the material of the ground layer from diffusing into the insulating layer is formed between the ground layer and the insulating layer. Suspension board. A ground layer forming step of forming a ground layer having a higher conductivity than the metal supporting substrate on the metal supporting substrate; an insulating layer forming step of forming an insulating layer on the metal supporting substrate and the ground layer; A wiring pattern forming step of forming a wiring pattern composed of a wiring pair on an insulating layer at a position where an average distance between an end of the wiring pair and an end of the ground layer is in a range of 50 μm to 100 μm; I have a,
The method for manufacturing a suspension board, wherein the metal support substrate has a recess, and the ground layer is formed in the recess .

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