JP5736722B2 - Suspension substrate, method for manufacturing suspension substrate, suspension, suspension with element, and hard disk drive - Google Patents

Description

  The present invention relates to a suspension substrate that prevents a seed layer under a wiring layer from being excessively etched.

  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. For this reason, higher functions are also required for suspension substrates (flexures) used in HDDs.

  As an example of a method for manufacturing a suspension substrate, a so-called semi-additive method is known. The semi-additive method is basically a method in which an insulating layer and a wiring layer are sequentially stacked on a metal support substrate. As a method for forming a wiring layer in the semi-additive method, typically, as shown in FIG. 15, a predetermined resist pattern 7 is formed on the surface of the seed layer 5 (FIG. 15A), and the resist is formed. The wiring layer 3 is deposited on the seed layer 5 exposed from the pattern 7 by electrolytic plating (FIG. 15B), and after removing the resist pattern 7 (FIG. 15C), the unnecessary seed layer 5 is removed. The method of doing can be mentioned.

  However, such a semi-additive method has a problem that so-called undercut is likely to occur. Specifically, there is a problem that the bottom width of the wiring layer 3 is locally reduced (FIG. 15C) due to the skirting portion 7a of the resist pattern 7 (FIG. 15A). Furthermore, as shown in FIG. 15 (d), when removing the seed layer 5, it is necessary to give priority to ensuring the insulation between the wiring layer 3 and other members. Etching has caused a problem that the width of the seed layer 5 becomes extremely small. When undercut occurs, there is a problem that the contact area between the wiring layer 3 and the insulating layer 2 decreases, and the adhesion of the wiring layer 3 decreases. In addition, chemicals and moisture used in subsequent processes are likely to remain in the space caused by undercuts, causing wiring corrosion (disconnection) and insulation failure (migration) over time, which is a major cause of reduced reliability. It was.

  To solve such a problem, FIG. 1 of Patent Document 1 discloses a method of filling a undercut portion by forming a metal layer on the entire surface after forming a wiring layer. However, this method can prevent undercutting of the wiring layer, but it is difficult to prevent undercutting of the seed layer. Further, FIG. 2 of Patent Document 2 discloses that a wiring layer is embedded in an insulating layer by hot pressing or the like. However, this method has a problem that the wiring layer is easily deformed because the wiring layer is embedded by hot pressing or the like. FIG. 3 of Patent Document 3 describes a structure in which the side surface of the bottom of the wiring layer is protected by a cover layer. However, with this structure, when the cover layer is formed, air bubbles are likely to be generated on the side surface of the bottom of the wiring layer, and it is difficult to sufficiently prevent the chemical liquid and moisture from remaining.

JP 2005-158848 A JP 2006-73761 A JP 2006-66451 A

  As described above, the undercut generated in the semi-additive method is strictly divided into an undercut of the wiring layer and an undercut of the seed layer. The undercut of the wiring layer can be prevented to some extent by controlling the shape of the resist pattern. On the other hand, regarding the undercut of the seed layer, since the thickness of the seed layer itself is thin, it is difficult to accurately control the etching amount. Furthermore, since it is necessary to give priority to ensuring the insulation between the wiring layer and other members, the seed layer is likely to be etched excessively. Further, not only the semi-additive method but also the so-called subtractive method, the seed layer is easily etched excessively for the same reason.

  The present invention has been made in view of the above problems, and a main object of the present invention is to provide a suspension substrate that prevents the seed layer existing under the wiring layer from being excessively etched.

  In order to solve the above problems, the present invention is a suspension substrate having a metal support substrate, an insulating layer formed on the metal support substrate, and a wiring layer formed on the insulating layer. The metal component of the first metal part formed on the insulating layer and the second metal part formed on the first metal part is interdiffused between the insulating layer and the wiring layer. There is provided a suspension substrate, wherein the second metal portion has a metal component different from that of the first metal portion.

  According to the present invention, the seed layer (the first metal part and the second metal part) existing under the wiring layer is transformed into the diffusion part, so that the diffusion part below the wiring layer is formed in the first metal layer etching step. The suspension substrate can be prevented from being etched.

  According to the present invention, there is also provided a suspension substrate having a metal support substrate, an insulating layer formed on the metal support substrate, and a wiring layer formed on the insulating layer, the insulating layer and Between the wiring layers, a first metal part formed on the insulating layer and a diffusion part formed by mutual diffusion of metal components of the wiring layer, the wiring layer includes the first metal part Provided is a suspension substrate characterized by having a metal component different from the above.

  According to the present invention, the diffusion layer under the wiring layer is etched in the first metal layer etching step by changing the seed layer (first metal portion) existing under the wiring layer into the diffusion portion. The suspension substrate can be prevented.

  In the said invention, it is preferable that the said spreading | diffusion part does not have an undercut part. This is because deterioration due to a chemical solution or moisture can be prevented and the adhesion between the insulating layer and the wiring layer can be maintained high.

  In the said invention, it is preferable that the material of said 1st metal part is an alloy containing Cr, Ti, or at least 1 type of these metal elements.

  In the said invention, it is preferable that the material of said 2nd metal part is Cu or Cu alloy.

  In the said invention, it is preferable that the material of the said wiring layer is Cu or Cu alloy.

  In the present invention, a metal support substrate, an insulating layer formed on the metal support substrate, a first metal layer formed on the insulating layer and having a portion serving as a first metal portion, and the first An intermediate member preparing step of preparing an intermediate member comprising a second metal portion formed on one metal portion and having a metal component different from the first metal portion, and a wiring layer formed on the second metal portion. And a diffusion part forming step of performing a heat treatment on the intermediate member to form a diffusion part formed by interdiffusing the metal components of the first metal part and the second metal part, and after the diffusion part forming step, And a first metal layer etching step of performing wet etching on the first metal layer.

  According to the present invention, by performing the diffusion portion forming step, the seed layer (first metal portion and second metal portion) existing under the wiring layer can be transformed into the diffusion portion, and the first metal layer etching is performed. In the process, the diffusion portion under the wiring layer can be prevented from being etched. The seed layer (diffusion part) altered in the lower part of the wiring layer has an etching characteristic different from that of the seed layer (first metal layer other than the diffusion part) which is not altered, so that appropriate etching is performed when the first metal layer is etched. By selecting the liquid, the first metal layer can be etched without almost etching the seed layer (diffusion part) under the wiring layer. That is, in the first metal layer etching step, it is possible to prevent the diffusion portion below the wiring layer from being etched.

  In the present invention, a metal support substrate, an insulating layer formed on the metal support substrate, a first metal layer formed on the insulating layer and having a portion serving as a first metal portion, and the first An intermediate member preparing step of preparing an intermediate member comprising a wiring layer having a metal component different from that of the first metal portion formed on the one metal portion, and heat-treating the intermediate member, the first metal A diffusion portion forming step for forming a diffusion portion formed by mutual diffusion of metal components of the wiring portion and the wiring layer, and a first metal layer etching step for wet etching the first metal layer after the diffusion portion formation step. A method for manufacturing a suspension substrate is provided.

  According to the present invention, by performing the diffusion portion forming step, the seed layer (first metal portion) existing under the wiring layer can be transformed into the diffusion portion. In the first metal layer etching step, the wiring layer It is possible to prevent the lower diffusion portion from being etched.

  Moreover, in this invention, the 1st metal layer formation which forms the insulating layer formation process which forms an insulating layer on a metal support substrate, and forms the 1st metal layer which has a part used as a 1st metal part on the said insulating layer. A resist pattern forming step for forming a resist pattern for forming a wiring layer on the first metal layer; and the first metal portion on the first metal portion exposed from the resist pattern. The second metal part forming step of forming a second metal part having a different metal component, the wiring layer forming step of forming a wiring layer on the second metal part, and after the wiring layer forming step, the resist pattern is formed. A resist pattern removing step for removing, and a first metal layer etching step for performing wet etching on the first metal layer after the resist pattern removing step, wherein the second metal portion forming step, the wiring After the forming step or the resist pattern removing step and before the first metal layer etching step, the metal components of the first metal portion and the second metal portion are mutually diffused by heat treatment. There is provided a method for manufacturing a suspension substrate, comprising a diffusion part forming step of forming a diffusion part.

  According to the present invention, by performing the diffusion portion forming step, the seed layer (first metal portion and second metal portion) existing under the wiring layer can be transformed into the diffusion portion, and the first metal layer etching is performed. In the process, the diffusion portion under the wiring layer can be prevented from being etched.

  The present invention also provides a suspension including the above-described suspension substrate.

  According to the present invention, by using the above-described suspension substrate, a suspension having high durability and long-term (aging) reliability can be obtained.

  The present invention also provides an element-equipped suspension comprising the above-described suspension and an element mounted in an element mounting region of the suspension.

  According to the present invention, by using the above-described suspension, a suspension with an element having high durability and long-term (long-term) reliability can be obtained.

  The present invention also provides a hard disk drive including the above-described suspension with an element.

  According to the present invention, a hard disk drive with higher operational reliability can be obtained by using the above-described suspension with an element.

  The suspension substrate of the present invention has an effect that the seed layer existing under the wiring layer can be prevented from being excessively etched.

It is a schematic diagram showing an example of a general suspension substrate. It is a schematic sectional drawing explaining the difference between the conventional suspension board | substrate and the suspension board | substrate of a 1st embodiment. It is a schematic sectional drawing explaining the board | substrate for suspensions of a 1st embodiment. It is a schematic sectional drawing explaining the board | substrate for suspensions of a 1st embodiment. It is a schematic sectional drawing explaining the board | substrate for suspensions of a 2nd embodiment. It is a schematic sectional drawing which shows an example of the manufacturing method of the board | substrate for suspensions of a 1st embodiment. It is a schematic sectional drawing which shows an example of the manufacturing method of the board | substrate for suspensions of a 1st embodiment by a semiadditive method. It is a schematic sectional drawing which shows the other example of the manufacturing method of the board | substrate for suspensions of a 1st embodiment by a semiadditive method. It is a schematic sectional drawing which shows the manufacturing method of the conventional board | substrate for suspensions by a semiadditive method. It is a schematic sectional drawing which shows an example of the manufacturing method of the board | substrate for suspensions of a 1st embodiment by a subtractive method. It is a schematic sectional drawing which shows an example of the manufacturing method of the board | substrate for suspensions of a 2nd embodiment. It is a schematic plan view which shows an example of the suspension of this invention. It is a schematic plan view which shows an example of the suspension with an element of this invention. It is a schematic plan view which shows an example of the hard disk drive of this invention. It is a schematic sectional drawing explaining the formation method of the conventional wiring layer by a semiadditive method.

  The suspension substrate, suspension substrate, suspension substrate manufacturing method, suspension, suspension with element, and hard disk drive of the present invention will be described in detail below.

A. Suspension Substrate The suspension substrate of the present invention is characterized by having a diffusion portion between an insulating layer and a wiring layer. The suspension substrate of the present invention can be roughly divided into two embodiments according to the aspect of the diffusion portion.

1. First Embodiment A suspension substrate according to a first embodiment is a suspension substrate having a metal support substrate, an insulating layer formed on the metal support substrate, and a wiring layer formed on the insulating layer. The metal component of the first metal part formed on the insulating layer and the second metal part formed on the first metal part interdiffuses between the insulating layer and the wiring layer. The second metal part has a metal component different from that of the first metal part.

  FIG. 1 is a schematic view showing an example of a general suspension substrate. FIG. 1A is a schematic plan view of a suspension substrate, and FIG. 1B is a sectional view taken along line XX of FIG. In FIG. 1A, the cover layer is not shown for convenience. A suspension substrate 20 shown in FIG. 1A includes an element mounting region 11 formed at one tip portion, an external circuit board connection region 12 formed at the other tip portion, an element mounting region 11 and an external portion. A plurality of wiring layers 13a to 13d for electrically connecting the circuit board connection region 12 are provided. The wiring layer 13a and the wiring layer 13b are a pair of wiring layers. Similarly, the wiring layer 13c and the wiring layer 13d are also a pair of wiring layers. One of these two wiring layers is a write wiring layer, and the other is a read wiring layer. On the other hand, as shown in FIG. 1B, the suspension substrate includes a metal support substrate 1, an insulating layer 2 formed on the metal support substrate 1, and a wiring layer 3 formed on the insulating layer 2. The cover layer 4 covering the wiring layer 3 and the seed layer 5 formed between the insulating layer 2 and the wiring layer 3 are provided.

  FIG. 2 is a schematic sectional view for explaining the difference between the conventional suspension substrate and the suspension substrate of the first embodiment. As shown in FIG. 2A, the conventional suspension substrate has an undercut portion 5 a formed in a seed layer 5 formed between the insulating layer 2 and the wiring layer 3. In the space of the undercut portion 5a, chemicals and moisture are likely to remain, and wiring corrosion (disconnection), insulation failure (migration), etc. occur over time, which has been a major cause of reduced reliability. On the other hand, as shown in FIG. 2B, the suspension substrate of the first embodiment does not have the above-described problem because the diffusion portion 6 is formed between the insulating layer 2 and the wiring layer 3. There is an advantage.

  FIG. 3 is a schematic cross-sectional view illustrating the suspension substrate according to the first embodiment. In FIG. 3A, a first metal part 6a (a part of the first metal layer 6A) is formed on the insulating layer 2, and a metal component different from the first metal part 6a is formed on the first metal part 6a. The 2nd metal part 6b which has is formed. In this state, by interdiffusing the metal components of the first metal part 6a and the second metal part 6b, the metal component of the second metal part 6b diffuses into the first metal part 6a, and the first metal part 6a A diffusion portion 6 with changed etching characteristics is obtained (FIG. 3B). Thereafter, the unnecessary first metal layer 6A is etched to leave only the diffusion portion 6 (FIG. 3C).

According to the first embodiment, the diffusion of the lower part of the wiring layer in the first metal layer etching step is performed by changing the seed layer (first metal part and second metal part) existing under the wiring layer into the diffusion part. It can be set as the suspension board | substrate which prevented that a part was etched. In addition, since the diffusion portion does not normally have an undercut portion, no chemical solution or moisture remains, and wiring corrosion (disconnection) or insulation failure (migration) over time can be prevented. Furthermore, since the diffusion portion does not have an undercut portion, the contact area between the wiring layer and the insulating layer can be sufficiently maintained, and the adhesion between them can be prevented from being lowered.
Hereinafter, the suspension substrate of the first embodiment will be described separately for the suspension substrate member and the configuration of the suspension substrate.

(1) Suspension Board Member First, the suspension board member of the first embodiment will be described. The suspension substrate according to the first embodiment has a metal support substrate, an insulating layer, a wiring layer, and a diffusion portion. The diffusion section will be described in detail in “(2) Configuration of suspension substrate” described later.

  The metal support substrate in the first embodiment functions as a support for the suspension substrate. The material of the metal support substrate is preferably a metal having spring properties, and specific examples include SUS. Moreover, although the thickness of a metal support substrate changes with kinds of the material, it exists in the range of 10 micrometers-20 micrometers, for example.

  The insulating layer in the first embodiment is formed on the metal support substrate. The material of the insulating layer is not particularly limited as long as it has insulating properties, and examples thereof include a resin. Examples of the resin include polyimide resin, polybenzoxazole resin, polybenzimidazole resin, acrylic resin, polyether nitrile resin, polyether sulfone resin, polyethylene terephthalate resin, polyethylene naphthalate resin, and polyvinyl chloride resin. Of these, polyimide resin is preferred. It is because it is excellent in insulation, heat resistance and chemical resistance. In addition, the material of the insulating layer may be a photosensitive material or a non-photosensitive material. The thickness of the insulating layer is, for example, preferably in the range of 5 μm to 30 μm, more preferably in the range of 5 μm to 18 μm, and still more preferably in the range of 5 μm to 12 μm.

  The wiring layer in the first embodiment is formed on the insulating layer. The material of the wiring layer is not particularly limited as long as it has conductivity, and examples thereof include metals such as copper (Cu), nickel (Ni), gold (Au), and these. An alloy containing at least one metal element is preferable, and Cu and a Cu alloy (particularly, an alloy containing Cu as a main component) are more preferable. The wiring layer is preferably formed by an electrolytic plating method. The thickness of the wiring layer is preferably in the range of 5 μm to 18 μm, for example, and more preferably in the range of 8 μm to 12 μm. Further, plating may be formed on the surface of a part of the wiring layer, particularly the surface of the part where the wiring layer is exposed without the cover layer on the wiring layer. This is because by providing plating on the wiring layer, deterioration (corrosion or the like) of the wiring layer can be prevented. Moreover, it is preferable that terminal plating is formed on the terminal portion for connection to the element or the external circuit board in order to form a joint portion with a conductive material such as solder or gold used for connection. When these platings are referred to as wiring plating parts, the type of wiring plating part is not particularly limited, and examples thereof include Ni plating and Au plating. Moreover, the wiring plating part may be composed of a single layer of plating or may be composed of two or more layers of plating. Among these, in the present invention, it is preferable that Ni plating and Au plating are sequentially formed from the surface side of the wiring layer. The thickness of the wiring plating portion is, for example, in the range of 0.1 μm to 4 μm.

  Examples of the wiring layer in the first embodiment include a write wiring layer, a read wiring layer, a noise shield wiring layer, a crosstalk prevention wiring layer, a power supply wiring layer, a ground wiring layer, and a heat assist wiring layer. , Flight height control wiring layer, sensor wiring layer, actuator wiring layer, and the like.

  In the first embodiment, it is preferable that a cover layer is formed so as to cover the wiring layer. This is because providing the cover layer can prevent the deterioration (corrosion or the like) of the wiring layer. Examples of the material for the cover layer include the resins described as the material for the insulating layer described above, and among them, a polyimide resin is preferable. The material of the cover layer may be a photosensitive material or a non-photosensitive material. The thickness of the cover layer is preferably in the range of 2 μm to 30 μm, for example, and more preferably in the range of 2 μm to 10 μm.

(2) Configuration of Suspension Substrate Next, the configuration of the suspension substrate of the first embodiment will be described. In the suspension substrate of the first embodiment, the metal component of the first metal part formed on the insulating layer and the second metal part formed on the first metal part is between the insulating layer and the wiring layer. It has a diffusion part formed by interdiffusion, and the second metal part is characterized by having a metal component different from that of the first metal part.

  The first metal part in the first embodiment preferably has a metal component different from that of the second metal part. Moreover, it is preferable that a 1st metal part has a metal component different from a wiring layer. Furthermore, the first metal part preferably has good adhesion to the insulating layer. This is because a wiring layer having good adhesion to the insulating layer can be obtained, and is effective in ensuring electrical reliability and mechanical reliability.

  The material of the first metal part is not particularly limited, but it can form a dense film, has a barrier effect against the reaction between the wiring layer and the insulating layer, and has excellent adhesion to the insulating layer. It is preferable that the electrical resistance is low. Furthermore, considering the selective etching property in the first metal layer etching step, the material of the first metal part contains, for example, a transition metal such as Cr, Ti, Ni, and at least one of these metal elements. Mention may be made of alloys. In addition, it is preferable that the said alloy contains the said transition metal as a main component.

  Moreover, the thickness of the first metal part is not particularly limited, but is preferably in the range of, for example, 0.001 μm to 5 μm, and more preferably in the range of 0.005 μm to 2 μm. If the thickness of the first metal part is too thin, the desired adhesion or the desired barrier effect against the reaction between the wiring layer and the insulating layer may not be obtained. This is because if the thickness is too large, the first metal portion may be peeled off from the insulating layer due to internal stress of the first metal portion itself. Examples of the method for forming the first metal portion (strictly, the first metal layer) include a PVD method and an electroless plating method. Among them, the PVD method is preferable, and the sputtering method is particularly preferable.

  The second metal part in the first embodiment is not particularly limited as long as it has a metal component different from that of the first metal part. When the metal component of the second metal part diffuses into the first metal part, the etching characteristics of the first metal part can be changed. The second metal portion may have the same metal component as that of the wiring layer, or may have a metal component different from that of the wiring layer. Moreover, it is preferable that a 2nd metal part is what makes a wiring layer easy to precipitate.

  The material of the second metal part is not particularly limited, but a material having low electric resistance and good adhesion to the first metal part is preferable. Since the wiring layer formed on the second metal part is typically Cu, the material of the second metal part is preferably Cu or a Cu alloy. Note that the Cu alloy preferably contains Cu as a main component.

  The thickness of the second metal part is not particularly limited, but is preferably in the range of 0.05 μm to 2 μm, for example, and more preferably in the range of 0.1 μm to 1 μm. If the thickness of the second metal part is too thin, the wiring layer typically formed by electroplating may not be deposited efficiently. If the thickness of the second metal part is too thick, This is because there is a possibility of causing deterioration of quality and poor quality. Moreover, as a formation method of a 2nd metal part, PVD method, the electroless-plating method, the electroplating method etc. can be mentioned, for example. Furthermore, the electrolytic plating method is preferably a strike plating method in consideration of the adhesion with the first metal part.

  The diffusion part in the first embodiment is formed by mutual diffusion of the metal components of the first metal part and the second metal part. When the metal component of the second metal part diffuses into the first metal part, the etching characteristics of the first metal part can be changed. That is, when the first metal layer is etched using a chemical that can selectively etch the first metal layer compared to other metals, the portion where the diffusion portion is formed has etching characteristics with the first metal layer. Since they are different, they are not etched or the etching rate is remarkably slowed. Therefore, the diffusion part in the first embodiment is preferably one in which the first metal part and the second metal part are almost entirely diffused.

  Whether or not the diffusion portion is formed can be confirmed by analyzing the ratio of the metal element in the thickness direction of the diffusion portion, for example, by XPS (X-ray photoelectron spectroscopy). In the first embodiment, the metal elements are interdiffused so that the diffusion portion is not etched until the etching of the non-interdiffused metal layer (first metal layer and / or second metal layer) is completed. Preferably it is. That is, it is preferable that the diffusion portion and the metal layer not interdiffused have a sufficient etching rate difference. Further, the thickness of the diffusion portion is not particularly limited, but is, for example, in the range of 0.001 μm to 5 μm, and preferably in the range of 0.005 μm to 2 μm.

Moreover, it is preferable that the spreading | diffusion part in a 1st embodiment does not have an undercut part. This is because deterioration due to a chemical solution or moisture can be prevented and the adhesion between the insulating layer and the wiring layer can be maintained high. “The diffusion portion does not have an undercut portion” can be defined as follows. Specifically, as shown in FIG. 4, and the lower end portion of the wiring layer 3, the distance L ₁ between the upper end portion of the diffuser portion 6 refers to is 1μm or less, it is preferable that among them 0.5μm or less . Also, the bottom width L ₂ of the spreading unit 6 is more preferable from the viewpoint of the adhesiveness of the wiring layer is in the range of 5Myuemu～40myuemu.

  In the suspension substrate of the first embodiment, it is preferable that the wiring layer is not embedded in the insulating layer. This is because deformation of the wiring layer due to hot pressing or the like can be prevented.

2. Second Embodiment Next, a second embodiment of the suspension substrate of the present invention will be described. A suspension substrate according to a second embodiment is a suspension substrate having a metal support substrate, an insulating layer formed on the metal support substrate, and a wiring layer formed on the insulating layer, Between the insulating layer and the wiring layer, a first metal portion formed on the insulating layer and a diffusion portion formed by interdiffusing metal components of the wiring layer, the wiring layer includes the first metal portion It has a metal component different from the one metal part.

  FIG. 5 is a schematic cross-sectional view illustrating the suspension substrate of the second embodiment. In FIG. 5A, a first metal part 6a (a part of the first metal layer 6A) is formed on the insulating layer 2, and a metal component different from the first metal part 6a is formed on the first metal part 6a. A wiring layer 3 is formed. In this state, by interdiffusing the metal components of the first metal part 6a and the wiring layer 3, the metal component of the wiring layer 3 diffuses into the first metal part 6a, and the etching characteristics of the first metal part 6a change. Thus, the diffused portion 6 is obtained (FIG. 5B). Thereafter, the unnecessary first metal layer 6A is etched to leave only the diffusion portion 6 (FIG. 5C).

  According to the second embodiment, the diffusion layer under the wiring layer is etched in the first metal layer etching step by changing the seed layer (first metal portion) existing under the wiring layer into the diffusion portion. Thus, the suspension substrate can be prevented. The suspension substrate of the second embodiment has the same effect as the suspension substrate of the first embodiment described above.

  In the second embodiment, the contents described in the first embodiment are the same as those described above except that a diffusion part formed by mutual diffusion of the metal components of the first metal part and the wiring layer is formed. Therefore, the description here is omitted. In particular, the diffusion portion in the second embodiment is preferably formed by diffusing a Cu component from the wiring layer to the first metal portion.

B. Next, a method for manufacturing a suspension substrate according to the present invention will be described. The manufacturing method of the suspension substrate of the present invention can be roughly divided into three embodiments.

1. First Embodiment A method for manufacturing a suspension substrate according to a first embodiment includes a metal support substrate, an insulating layer formed on the metal support substrate, and a portion that is formed on the insulating layer and serves as a first metal portion. A first metal layer, a second metal part formed on the first metal part and having a metal component different from the first metal part, and a wiring layer formed on the second metal part. An intermediate member preparation step for preparing an intermediate member to be provided, and a diffusion portion formation in which a heat treatment is performed on the intermediate member to form a diffusion portion formed by mutual diffusion of the metal components of the first metal portion and the second metal portion And a first metal layer etching step of performing wet etching on the first metal layer after the diffusion portion forming step.

  FIG. 6 is a schematic cross-sectional view showing an example of a manufacturing method of the suspension substrate of the first embodiment. In FIG. 6, first, the metal support substrate 1, the insulating layer 2 formed on the metal support substrate 1, the insulating layer 2 formed on the metal support substrate 1, the first metal portion 6a, Formed on the first metal layer 6A, the first metal part 6a, the second metal part 6b having a metal component different from the first metal part 6a, and the second metal part 6b. An intermediate member 15 including the wiring layer 3 is prepared (FIG. 6A). Next, the intermediate member 15 is heat-treated using the heating element 16 to form a diffusion portion 6 in which the metal components of the first metal portion 6a and the second metal portion 6b are mutually diffused (FIG. 6 ( b)). At this time, in order to prevent unnecessary oxidation, it is preferable to perform heat treatment in an inert gas atmosphere (for example, an Ar gas atmosphere). Next, the unnecessary first metal layer 6A is removed by wet etching (FIG. 6C). Thereby, the suspension substrate 20 is obtained (FIG. 6D).

According to the first embodiment, by performing the diffusion portion forming step, the seed layer (first metal portion and second metal portion) existing under the wiring layer can be transformed into the diffusion portion, and the first metal In the layer etching step, it is possible to prevent the diffusion portion under the wiring layer from being etched. Further, as in Patent Document 1, it is not necessary to form a new metal layer in the wiring layer as compared with the method of forming the metal layer on the entire surface after forming the wiring layer and filling the undercut portion. There is an advantage that pattern miniaturization is easy. Further, unlike Patent Document 2, there is an advantage that deformation of the wiring layer can be prevented because it is not necessary to perform hot pressing or the like, compared to a method in which the wiring layer is embedded in the insulating layer by hot pressing or the like. Further, unlike Patent Document 3, it is not necessary to protect the side surface of the bottom of the wiring layer with the cover layer, so that it is not necessary to protect the side with the cover layer. There is an advantage that the generated bubbles do not occur.
Hereinafter, the manufacturing method of the suspension substrate according to the first embodiment will be described step by step.

(1) Intermediate member preparation step The intermediate member preparation step in the first embodiment is a metal support substrate, an insulating layer formed on the metal support substrate, and formed on the insulating layer to be a first metal portion. A first metal layer having a part, a second metal part formed on the first metal part and having a metal component different from the first metal part, and a wiring layer formed on the second metal part, It is the process of preparing an intermediate member provided with.

  The method for preparing the intermediate member is not particularly limited as long as the intermediate member can be obtained, and may be a semi-additive method or a subtractive method.

(I) Semi-additive method The intermediate member preparation process by a semi-additive method can mention the following two forms, for example. In the first form, the intermediate member preparation step forms an insulating layer forming step of forming an insulating layer on the metal supporting substrate, and forms a first metal layer having a portion that becomes the first metal portion on the insulating layer. A first metal layer forming step; a resist pattern forming step for forming a resist pattern for forming a wiring layer on the first metal layer; and the first metal portion exposed from the resist pattern on the first metal portion. A second metal part forming step of forming a second metal part having a metal component different from the one metal part; a wiring layer forming step of forming a wiring layer on the second metal part; and after the wiring layer forming step And a resist pattern removing step for removing the resist pattern.

  This first embodiment will be described with reference to FIG. In FIG. 7, first, a metal support substrate 1 is prepared (FIG. 7A), and an insulating layer 2 is formed on the metal support substrate 1 (FIG. 7B). The formation method of the insulating layer 2 is preferably selected as appropriate according to the material of the insulating layer 2. For example, when the material of the insulating layer 2 is a photosensitive material, the patterned insulating layer 2 can be obtained by coating the photosensitive material on a metal supporting substrate and then performing predetermined exposure and development. it can. On the other hand, when the material of the insulating layer 2 is a non-photosensitive material, a predetermined resist pattern is formed using a dry film resist (DFR) or the like after the non-photosensitive material is coated on a metal supporting substrate. Then, the patterned insulating layer 2 can be obtained by etching the portion exposed from the resist pattern.

  Next, a first metal layer 6A having a portion to be a first metal part is formed on the insulating layer 2 (FIG. 7C). Examples of the method for forming the first metal layer 6A include a PVD method and an electroless plating method. Among them, the PVD method is preferable, and the sputtering method is particularly preferable. Next, a resist pattern 7 for forming a wiring layer is formed on the first metal layer 6A (FIG. 7D). As a method for forming the resist pattern 7, for example, a method of applying DFR and performing predetermined exposure and development can be mentioned. Next, a second metal portion 6b having a metal component different from that of the first metal portion 6a is formed on the first metal portion 6a exposed from the resist pattern 7 (FIG. 7E). Examples of the method for forming the second metal portion 6b include an electrolytic plating method, an electroless plating method, and a PVD method. Among them, the electrolytic plating method is preferable, and the strike plating method is more preferable. Next, the wiring layer 3 is formed on the second metal portion 6b (FIG. 7F). Examples of the method for forming the wiring layer 3 include an electrolytic plating method. Next, the intermediate member 15 is obtained by removing the resist pattern 7 (FIG. 7G).

  Thereafter, similarly to the above-described FIGS. 6B to 6D, the diffusion portion 6 is formed by heat treatment (FIG. 7H), and the unnecessary first metal layer 6A is wet-etched (FIG. 7I). Further, by forming the cover layer 4 covering the wiring layer 3, a suspension substrate can be obtained (FIG. 7 (j)).

  In the first embodiment, by using an electrolytic plating method (especially strike plating method), the second metal portion is efficiently provided only at the lower portion of the wiring layer where the opening of the resist pattern 7, that is, the diffusion portion needs to be formed. There is an advantage that it can be formed. Therefore, the occurrence of undercut portions can be more effectively prevented.

  On the other hand, in the second aspect, the intermediate member preparing step includes an insulating layer forming step in which an insulating layer is formed on the metal supporting substrate, and a first metal layer having a portion that becomes the first metal portion on the insulating layer. Forming a first metal layer, and forming a second metal layer on the first metal layer, the second metal layer having a metal component different from the first metal portion and having a portion to be the second metal portion. Forming a resist pattern for forming a wiring layer on the second metal layer; forming a resist pattern on the second metal layer; and forming a wiring layer on the second metal portion exposed from the resist pattern. A wiring layer forming step to be formed; a resist pattern removing step of removing the resist pattern after the wiring layer forming step; and a second metal portion forming step of etching the second metal layer to form the second metal portion. And a form having .

  This second embodiment will be described with reference to FIG. In FIG. 8, first, a metal support substrate 1 is prepared (FIG. 8A), and an insulating layer 2 is formed on the metal support substrate 1 thereon (FIG. 8B). The method for forming the insulating layer 2 is the same as in the first embodiment. Hereinafter, description of the formation method overlapping with the first embodiment is omitted. Next, a first metal layer 6A having a portion to be a first metal part is formed on the insulating layer 2, and a metal component different from the first metal part is formed on the first metal layer 6A. A second metal layer 6B having a portion to be a bimetallic portion is formed (FIG. 8C). The method for forming the second metal layer 6B is the same as the method for forming the first metal layer 6A described above.

  Next, a resist pattern 7 for forming a wiring layer is formed on the second metal layer 6B (FIG. 8D). Next, the wiring layer 3 is formed on the second metal portion 6b (FIG. 8E). Next, the resist pattern 7 is removed (FIG. 8F), the second metal layer 6B is etched, and the second metal portion 6b is formed, thereby obtaining the intermediate member 15 (FIG. 8G). Examples of the method for etching the second metal layer 6B include wet etching and dry etching. Further, when the second metal layer 6B is wet-etched, the material of the second metal layer 6B and the material of the wiring layer 3 are preferably the same. This is because the side surfaces of the second metal layer 6B and the wiring layer 3 are etched at the same time, thereby effectively preventing the occurrence of an undercut portion. The etchant used for etching the second metal layer 6B is preferably an etchant (highly selective etchant) that etches the second metal layer but does not etch the first metal layer.

  Thereafter, similarly to the above-described FIGS. 6B to 6D, the diffusion portion 6 is formed by heat treatment (FIG. 8H), and the unnecessary first metal layer 6A is wet-etched (FIG. 8I). )). Furthermore, by forming the cover layer 4 covering the wiring layer 3, a suspension substrate can be obtained (FIG. 8 (j)).

  In the second mode, since the first metal layer and the second metal layer are generally formed on the entire surface, it is possible to continuously form the first metal layer and the second metal layer. There is an advantage that simplification can be achieved.

  Here, FIG. 9 is a schematic cross-sectional view for explaining a conventional method for manufacturing a suspension substrate. FIGS. 9A to 9G are the same as FIGS. 8A to 8G. Conventionally, since the unnecessary first metal layer 6A is etched without applying heat treatment to the intermediate member 15, an undercut portion is generated in the first metal portion 6a (FIG. 9 (h)). On the other hand, in the first embodiment, since the diffusion portion is formed before the first metal layer 6A is etched, an undercut portion can be prevented from occurring in the first metal portion 6a.

(Ii) Subtractive method The intermediate member preparation step by the subtractive method includes, for example, a metal supporting board, an insulating member formed on the metal supporting member, a first metal layer formed on the insulating member, A laminated member for preparing a laminated member formed on the first metal layer and having a second metal layer having a metal component different from the first metal layer and a conductor layer formed on the second metal layer A preparation step, a resist pattern forming step of forming a resist pattern for forming a wiring layer on the conductor layer of the laminated member, and etching the conductor layer exposed from the resist pattern to form a wiring layer The resist pattern is removed after the wiring layer forming step, the second metal layer forming step of etching the second metal layer to form the second metal portion, and the second metal portion forming step. A resist pattern removal step include those having.

  This intermediate member preparation step will be described with reference to FIG. In FIG. 10, first, the metal supporting board 1, the insulating member 2X formed on the metal supporting member 1, the first metal layer 6A formed on the insulating member 2X, and the first metal layer 6A are formed. A laminated member having the second metal layer 6B thus formed and the conductor layer 3X formed on the second metal layer 6B is prepared (FIG. 10A). As this laminated member, a commercially available one may be used, or one obtained by sequentially forming each layer on a metal support substrate may be used. Next, a resist pattern 7 for forming a wiring layer is formed on the conductor layer 3X of the laminated member (FIG. 10B). The method for forming the resist pattern 7 is the same as in the first embodiment. Hereinafter, description of the formation method overlapping with the first embodiment is omitted.

  Next, the conductor layer 3X exposed from the resist pattern 7 is etched to form the wiring layer 3 (FIG. 10C). At this time, when the material of the conductor layer 3X and the material of the second metal layer 6B are the same, the second metal layer 6B is preferably etched at the same time to form the second metal portion 6b. Examples of the method for etching the conductor layer 3X include wet etching. It is preferable that an etching solution used for wet etching is appropriately selected according to the material of the conductor layer 3X. For example, when the material of the conductor layer 3X is copper, for example, an iron chloride based etchant can be used. Next, the intermediate member 15 is obtained by removing the resist pattern 7 (FIG. 10D).

  Thereafter, similarly to FIGS. 6B to 6D described above, the diffusion portion 6 is formed by heat treatment (FIG. 10E), and the unnecessary first metal layer 6A is wet-etched (FIG. 10F). )). Furthermore, a suspension substrate can be obtained by forming the cover layer 4 covering the wiring layer 3 and etching the insulating member 2X to form the insulating layer 2 (FIG. 10G). As a method for etching the insulating member 2X, for example, wet etching can be exemplified. It is preferable to appropriately select an etching solution used for wet etching according to the material of the insulating member 2X. For example, when the material of the insulating member 2X is a polyimide resin, for example, an alkaline etching solution or the like can be used.

  In the subtractive method, the process is simpler than that in the semi-additive method, so that a wiring layer can be formed at a low cost. In addition, there is an advantage that an intermediate member having a uniform wiring layer thickness can be obtained, and impedance design is facilitated.

(2) Diffusion part formation process The diffusion part formation process in a 1st embodiment heat-processes with respect to the above-mentioned intermediate member, and a diffusion part formed by metal diffusion of the 1st metal part and the 2nd metal part mutually diffusing Is a step of forming.

  The heating temperature of the heat treatment is not particularly limited as long as the metal component of the first metal part and the second metal part can diffuse each other, but is preferably in the range of 200 ° C to 400 ° C, for example. More preferably, it is in the range of 250 ° C to 350 ° C. This is because if the heating temperature is too low, a lot of time may be required until mutual diffusion occurs, and if the heating temperature is too high, for example, the insulating layer may be deteriorated. Moreover, it is preferable to adjust suitably the time of heat processing so that a desired diffusion part may be formed. The heat treatment method is not particularly limited as long as it is a method capable of forming a diffusion portion, and examples thereof include a method using a heating element, a method using a hot air oven, and a method using an infrared lamp.

The atmosphere for the heat treatment is not particularly limited, but is preferably a non-oxidizing atmosphere, and more preferably an inert gas atmosphere. This is because the oxidation of the wiring layer can be prevented. As an inert gas atmosphere, Ar gas atmosphere etc. can be mentioned, for example. Although not a inert gas, a non-oxidizing atmosphere may also be used, for example N ₂ gas atmosphere. For example, in FIGS. 7F to 7H, heat treatment is performed after removing the resist pattern 7. If the resist pattern 7 has a predetermined heat resistance, the resist pattern 7 is removed. Heat treatment may be performed before removal. In this case, the intermediate member 15 further has a resist pattern 7.

(3) First metal layer etching step The first metal layer etching step in the first embodiment is a step of performing wet etching on the first metal layer after the diffusion portion forming step.

  The etchant used for wet etching of the first metal layer is preferably an etchant (highly selective etchant) that etches the first metal layer but does not etch the diffusion portion. For example, the material of the second metal part is Cu or a Cu alloy (particularly an alloy containing Cu as a main component), and the material of the first metal layer is Cr or a Cr alloy (particularly an alloy containing Cr as a main component). In this case, as the etching solution, for example, an alkaline etching solution mainly composed of potassium ferricyanide or potassium permanganate can be used. The material of the second metal part is Cu or a Cu alloy (particularly an alloy containing Cu as a main component), and the material of the first metal layer is Ti or a Ti alloy (particularly an alloy containing Ti as a main component). In this case, as the etching solution, for example, an ammonium fluoride / hydrofluoric acid mixed solution or an etching solution containing hydrosilicofluoric acid can be used. Examples of the wet etching method include a method of spraying an etching solution by spraying, a method of immersing an intermediate member having a diffusion portion in the etching solution, and the like. Further, the wet etching time is not particularly limited, and it is preferable to adjust the wet etching time to such a degree that a desired insulating property can be secured.

(4) Other steps The suspension substrate manufacturing method of the first embodiment may include a cover layer forming step of forming a cover layer covering the wiring layer after the first metal layer etching step. . The method for forming the cover layer is preferably selected as appropriate according to the material of the cover layer. For example, when the material of the cover layer is a photosensitive material, a patterned cover layer can be obtained by coating the photosensitive material so as to cover the wiring layer and then performing predetermined exposure and development. . On the other hand, when the material of the cover layer is a non-photosensitive material, after applying the non-photosensitive material so as to cover the wiring layer, a predetermined resist pattern is formed using a dry film resist (DFR) or the like. By forming and etching the portion exposed from the resist pattern, a patterned cover layer can be obtained.

  The suspension substrate manufacturing method according to the first embodiment includes a step of processing a metal support substrate into a predetermined shape, a step of forming a wiring plating portion in the wiring layer, a penetrating insulating layer, the metal support substrate and the wiring layer It is preferable to include a step of forming a via for electrically connecting the two.

2. Second Embodiment Next, a second embodiment of the method for manufacturing a suspension substrate according to the present invention will be described. A method for manufacturing a suspension substrate according to a second embodiment includes a metal support substrate, an insulating layer formed on the metal support substrate, and a first metal portion formed on the insulating layer and serving as a first metal portion. An intermediate member preparation step of preparing an intermediate member comprising a metal layer and a wiring layer formed on the first metal portion and having a metal component different from the first metal portion; and heat treatment of the intermediate member A diffusion portion forming step for forming a diffusion portion formed by mutual diffusion of metal components of the first metal portion and the wiring layer, and a first metal for wet etching the first metal layer after the diffusion portion formation step And a layer etching step.

  FIG. 11 is a schematic cross-sectional view showing an example of a manufacturing method of the suspension substrate of the second embodiment. In FIG. 11, first, the metal support substrate 1, the insulating layer 2 formed on the metal support substrate 1, the insulating layer 2 formed on the metal support substrate 1, the first metal portion 6a, An intermediate member 15 including a first metal layer 6A having a portion to be formed and a wiring layer 3 formed on the first metal portion 6a and having a metal component different from that of the first metal portion 6a is prepared (FIG. 11A). )). Next, heat treatment is performed on the intermediate member 15 to form the diffusion portion 6 in which the metal components of the first metal portion 6a and the wiring layer 3 are mutually diffused (FIG. 11B). At this time, in order to prevent unnecessary oxidation, it is preferable to perform heat treatment in an inert gas atmosphere (for example, an Ar gas atmosphere). Next, the unnecessary first metal layer 6A is removed by wet etching (FIG. 11C). Thereby, the suspension substrate 20 is obtained (FIG. 11D).

  According to the second embodiment, by performing the diffusion portion forming step, the seed layer (first metal portion) existing under the wiring layer can be transformed into the diffusion portion. In the first metal layer etching step, It is possible to prevent the diffusion portion below the wiring layer from being etched. Moreover, the manufacturing method of the suspension substrate of the second embodiment has the same effects as the manufacturing method of the suspension substrate of the first embodiment described above.

  In the second embodiment, the contents are the same as those described in the first embodiment except that a diffusion portion formed by mutual diffusion of the metal components of the first metal portion and the wiring layer is formed.

  In the intermediate member preparation step by the semi-additive method, for example, an insulating layer forming step of forming an insulating layer on a metal supporting substrate, and a first metal layer having a portion to be a first metal portion on the insulating layer are formed. A first metal layer forming step; a resist pattern forming step for forming a resist pattern for forming a wiring layer on the first metal layer; and the first metal portion exposed from the resist pattern on the first metal portion. Examples thereof include a wiring layer forming step for forming a wiring layer having a metal component different from one metal portion, and a resist pattern removing step for removing the resist pattern after the wiring layer forming step.

  On the other hand, the intermediate member preparation step by the subtractive method includes, for example, a metal support substrate, an insulating member formed on the metal supporting member, a first metal layer formed on the insulating member, and the first metal. A laminated member preparing step of preparing a laminated member having a conductor layer having a metal component different from that of the first metal layer, and forming a wiring layer on the conductor layer of the laminated member A resist pattern forming step for forming the resist pattern, a wiring layer forming step for etching the conductor layer exposed from the resist pattern to form a wiring layer, and a resist for removing the resist pattern after the wiring layer forming step And a pattern removing step.

3. Third Embodiment Next, a third embodiment of the method for manufacturing a suspension substrate according to the present invention will be described. A method for manufacturing a suspension substrate according to a third embodiment includes an insulating layer forming step of forming an insulating layer on a metal supporting substrate, and forming a first metal layer having a portion that becomes a first metal portion on the insulating layer. A first metal layer forming step, a resist pattern forming step for forming a resist pattern for forming a wiring layer on the first metal layer, and the first metal portion exposed from the resist pattern, A second metal part forming step for forming a second metal part having a metal component different from the first metal part; a wiring layer forming step for forming a wiring layer on the second metal part; and the wiring layer forming step. A resist pattern removing step for removing the resist pattern, and a first metal layer etching step for wet etching the first metal layer after the resist pattern removing step. After the metal part forming step, the wiring layer forming step, or the resist pattern removing step and before the first metal layer etching step, the first metal portion and the second metal portion are subjected to heat treatment. It has the diffusion part formation process which forms the diffusion part which a metal component mutually diffuses, It is characterized by the above-mentioned.

  An example of the manufacturing method of the suspension substrate of the third embodiment is basically the same as that shown in FIG. In the first mode described in the above-mentioned “B. Manufacturing method of suspension substrate 1. First embodiment (1) Intermediate member preparation step (i) Semi-additive method”, a patterned first plate is formed on the first metal layer. A bimetallic part is formed. Therefore, after the second metal part forming step (FIG. 7 (e)), after the wiring layer forming step (FIG. 7 (f)), or after the resist pattern removing step (FIG. 7 (g)), And if the diffusion part 6 is formed before a 1st metal layer etching process (FIG.7 (i)), the effect similar to a 1st embodiment will be acquired.

  According to the third embodiment, the seed layer (first metal part and second metal part) existing under the wiring layer can be transformed into the diffusion part by performing the diffusion part forming step, and the first metal In the layer etching step, it is possible to prevent the diffusion portion under the wiring layer from being etched. Moreover, the manufacturing method of the suspension substrate of the third embodiment has the same effect as the manufacturing method of the suspension substrate of the first embodiment described above.

C. Suspension Next, the suspension of the present invention will be described. The suspension of the present invention includes the above-described suspension substrate.

  According to the present invention, by using the above-described suspension substrate, a suspension having high durability and long-term (aging) reliability can be obtained.

  FIG. 12 is a schematic plan view showing an example of the suspension of the present invention. A suspension 40 shown in FIG. 12 includes the suspension substrate 20 described above and a load beam 30 provided on the surface of the suspension substrate 20 opposite to the surface on which the element mounting region 11 is formed. is there.

  The suspension of the present invention has at least a suspension substrate, and usually further has a load beam. The suspension substrate is the same as the content described in “A. Suspension substrate”, and therefore, the description thereof is omitted here. The load beam can be the same as the load beam used for a general suspension.

D. Next, the suspension with an element of the present invention will be described. A suspension with an element of the present invention includes the above-described suspension and an element mounted in an element mounting region of the suspension.

  According to the present invention, by using the above-described suspension, a suspension with an element having high durability and long-term (long-term) reliability can be obtained.

  FIG. 13 is a schematic plan view showing an example of the suspension with an element of the present invention. A suspension with an element 50 shown in FIG. 13 includes the suspension 40 described above and an element 41 mounted on the element mounting region 11 of the suspension 40.

  The suspension with an element of the present invention has at least a suspension and an element. The suspension is the same as the content described in “C. Suspension”, and therefore, the description thereof is omitted here. In addition, examples of elements mounted in the element mounting area include a magnetic head slider, an actuator, and a semiconductor. The actuator may have a magnetic head or may not have a magnetic head.

E. Next, the hard disk drive of the present invention will be described. The hard disk drive of the present invention is characterized by including the above-described suspension with an element.

  According to the present invention, a hard disk drive with higher operational reliability can be obtained by using the above-described suspension with an element.

  FIG. 14 is a schematic plan view showing an example of the hard disk drive of the present invention. The hard disk drive 60 shown in FIG. 14 includes the above-described suspension 50 with an element, a disk 51 on which the element suspension 50 writes and reads data, a spindle motor 52 that rotates the disk 51, and the elements of the suspension 50 with an element. And a voice coil motor 54, and a case 55 for sealing the above-described members.

  The hard disk drive of the present invention has at least a suspension with an element, and usually further includes a disk, a spindle motor, an arm, and a voice coil motor. The suspension with an element is the same as that described in the above “D. Suspension with an element”, and therefore description thereof is omitted here. As other members, the same members as those used in a general hard disk drive can be used.

  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]
First, SUS304 (metal support substrate 1) having a thickness of 20 μm was prepared (FIG. 7A). Next, a photosensitive polyimide resin was applied onto SUS, mask exposure, development, and curing were performed to form an insulating layer 2 having a thickness of 10 μm (FIG. 7B). Next, a Cr film (first metal layer 6A) having a thickness of 0.05 μm was formed on the entire surface of the insulating layer 2 by sputtering (FIG. 7C). Next, DFR was laminated on the surface of the first metal layer 6A, and exposure and development were performed to form a resist pattern 7 (FIG. 7D). Next, a Cu layer (second metal portion 6b) having a thickness of 0.2 μm was formed on the first metal portion 6a exposed from the resist pattern 7 by strike plating (FIG. 7E). Next, a Cu layer (wiring layer 3) having a thickness of 10 μm was formed on the second metal portion 6b by electrolytic plating (FIG. 7F). Next, the resist pattern 7 was peeled off with an alkaline solution (FIG. 7G).

  Thereafter, heat treatment was performed in an oven in a nitrogen atmosphere at 300 ° C. for 60 minutes to form a diffusion portion 6 (FIG. 7H). Next, the unnecessary first metal layer 6A was removed with a Cr selective etching solution (potassium ferricyanide alkaline etching solution) (FIG. 7 (i)). Next, a photosensitive polyimide resin was applied so as to cover the wiring layer 3, mask exposure, development, and curing were performed to form a cover layer 4 having a thickness of 5 μm (FIG. 7J). Further, Ni plating (0.5 μm) and Au plating (1 μm) were performed on the terminal portion of the wiring layer to form a wiring plating portion. As a result, a suspension substrate was obtained.

When the cross section of the obtained suspension substrate was observed, L ₁ in FIG. 4 was 0.1 μm, and it was confirmed that the diffusion portion was hardly etched.

[Example 2]
First, SUS304 (metal support substrate 1) having a thickness of 20 μm was prepared (FIG. 8A). Next, a photosensitive polyimide resin was applied onto SUS, and mask exposure, development, and curing were performed to form an insulating layer 2 having a thickness of 10 μm (FIG. 8B). Next, a 0.05 μm thick Cr film (first metal layer 6A) and a 0.2 μm thick Cu film (second metal layer 6B) were formed on the entire surface of the insulating layer 2 by sputtering (FIG. 8 (c)). Next, DFR was laminated on the surface of the second metal layer 6B, and exposure and development were performed to form a resist pattern 7 (FIG. 8D). Next, a Cu layer (wiring layer 3) having a thickness of 10 μm was formed on the second metal portion 6b exposed from the resist pattern 7 by electrolytic plating (FIG. 8E). Next, the resist pattern 7 was peeled off with an alkaline solution (FIG. 8F).

  Thereafter, unnecessary second metal layer 6B was removed with a Cu selective etching solution (a mixed solution of a general oxidizing agent and dilute acid) (FIG. 8G). Next, heat treatment was performed in a nitrogen atmosphere oven at 300 ° C. for 60 minutes to form the diffusion portion 6 (FIG. 8H). Next, the unnecessary first metal layer 6A was removed with a Cr selective etching solution (potassium ferricyanide alkaline etching solution) (FIG. 8 (i)). Next, a photosensitive polyimide resin was applied so as to cover the wiring layer 3, mask exposure, development, and curing were performed to form a cover layer 4 having a thickness of 5 μm (FIG. 8J). Further, Ni plating (0.5 μm) and Au plating (1 μm) were performed on the terminal portion of the wiring layer to form a wiring plating portion. As a result, a suspension substrate was obtained.

When the cross section of the obtained suspension substrate was observed, L ₁ in FIG. 4 was 0.15 μm, and it was confirmed that the diffusion portion was hardly etched.

[Comparative Example 1]
A suspension substrate was obtained in the same manner as in Example 2 except that the heat treatment was not performed (FIG. 9). Observation of the cross section of the substrate for suspension, L ₃ in FIG. 9 (i) is 2.0 .mu.m, the first metal portion 6a has been confirmed to have an undercut. Incidentally, L ₃ has a lower end portion of the second metal portion 6b, the distance between the upper end portion of the first metal portion 6a.

[Example 3]
This example is basically the same as Example 1, but a wiring layer was formed on the first metal part without the second metal part. First, SUS304 (metal support substrate) having a thickness of 20 μm was prepared. Next, a photosensitive polyimide resin was applied onto SUS, mask exposure, development, and curing were performed to form an insulating layer having a thickness of 10 μm. Next, a Cr film (first metal layer) having a thickness of 0.01 μm was formed on the entire surface of the insulating layer by sputtering. Next, DFR was laminated on the surface of the first metal layer, and exposure and development were performed to form a resist pattern. Next, a Cu layer (wiring layer) having a thickness of 10 μm was formed on the first metal portion exposed from the resist pattern by electrolytic plating. Next, the resist pattern was peeled off with an alkaline solution.

  Thereafter, heat treatment was performed in an oven in a nitrogen atmosphere at 300 ° C. for 60 minutes to form a diffusion portion. Next, the unnecessary 1st metal layer was removed with Cr selective etching liquid (potassium ferricyanide alkaline etching liquid). Next, a photosensitive polyimide resin was applied so as to cover the wiring layer, mask exposure, development and curing were performed to form a cover layer having a thickness of 5 μm. Further, Ni plating (0.5 μm) and Au plating (1 μm) were performed on the terminal portion of the wiring layer to form a wiring plating portion. As a result, a suspension substrate was obtained.

When the cross section of the obtained suspension substrate was observed, L ₁ in FIG. 4 was 0.1 μm, and it was confirmed that the diffusion portion was hardly etched.

[Example 4]
First, a non-photosensitive polyimide resin is applied and cured on SUS304 (metal support substrate 1) having a thickness of 20 μm to form an insulating member 2X having a thickness of 10 μm. Next, on the entire surface of the insulating member 2X, A Cr film (first metal layer 6A) having a thickness of 0.05 μm and a Cu film (second metal layer 6B) having a thickness of 0.2 μm are formed by sputtering, and further, a thickness of 10 μm is formed by electrolytic plating on the entire surface. A Cu layer (conductor layer 3X) was formed to obtain a laminated member (FIG. 10A). Next, DFR was laminated on the surface of the conductor layer 3X of the laminated member, and exposure and development were performed to form a resist pattern 7 (FIG. 10B).

  Next, the conductor layer 3X exposed from the resist pattern 7 was etched with an iron chloride etching solution to form the wiring layer 3 (FIG. 10C). At this time, since the material of the conductor layer 3X and the material of the second metal layer 6B are the same, the second metal layer 6B was also etched at the same time to form the second metal portion 6b. Next, the intermediate member 15 was produced by removing the resist pattern 7 (FIG. 10D).

  Thereafter, heat treatment was performed in an oven in a nitrogen atmosphere at 300 ° C. for 60 minutes to form a diffusion portion. Next, the unnecessary 1st metal layer was removed with Cr selective etching liquid (potassium ferricyanide alkaline etching liquid). Next, a photosensitive polyimide resin was applied so as to cover the wiring layer, mask exposure, development and curing were performed to form a cover layer having a thickness of 5 μm. Further, Ni plating (0.5 μm) and Au plating (1 μm) were performed on the terminal portion of the wiring layer to form a wiring plating portion. As a result, a suspension substrate was obtained.

When the cross section of the obtained suspension substrate was observed, L ₁ in FIG. 4 was 0.12 μm, and it was confirmed that the diffusion portion was hardly etched.

  DESCRIPTION OF SYMBOLS 1 ... Metal support substrate, 2 ... Insulating layer, 3 ... Wiring layer, 4 ... Cover layer, 5 ... Seed layer, 5a ... Undercut part, 6 ... Diffusion part, 6a ... First metal part, 6b ... Second metal part 6A ... 1st metal layer, 6B ... 2nd metal layer, 7 ... Resist pattern, 7a ... Bottoming part, 11 ... Element mounting area, 12 ... External circuit board connection area, 13 ... Wiring layer, 15 ... Intermediate member, 16 ... heating element, 20 ... suspension substrate,

Claims (12)

A suspension substrate having a metal support substrate, an insulating layer formed on the metal support substrate, and a wiring layer formed on the insulating layer,
Diffusion formed by interdiffusion of metal components between the first metal part formed on the insulating layer and the second metal part formed on the first metal part between the insulating layer and the wiring layer Part
The suspension substrate according to claim 1, wherein the second metal portion has a metal component different from that of the first metal portion. A suspension substrate having a metal support substrate, an insulating layer formed on the metal support substrate, and a wiring layer formed on the insulating layer,
Between the insulating layer and the wiring layer, a first metal part formed on the insulating layer and a diffusion part formed by interdiffusing metal components of the wiring layer,
The suspension board according to claim 1, wherein the wiring layer has a metal component different from that of the first metal portion. The suspension substrate according to claim 1, wherein the diffusion portion does not have an undercut portion. 4. The material according to claim 1, wherein the material of the first metal part is Cr, Ti, or an alloy containing at least one of these metal elements. Suspension substrate. The suspension substrate according to claim 1, wherein the material of the second metal part is Cu or a Cu alloy. The suspension substrate according to any one of claims 1 to 5, wherein a material of the wiring layer is Cu or a Cu alloy. A metal support substrate; an insulating layer formed on the metal support substrate; a first metal layer formed on the insulating layer and having a portion to be a first metal portion; and formed on the first metal portion. An intermediate member preparing step of preparing an intermediate member comprising a second metal portion having a metal component different from the first metal portion and a wiring layer formed on the second metal portion;
A diffusion part forming step of performing a heat treatment on the intermediate member and forming a diffusion part formed by mutual diffusion of metal components of the first metal part and the second metal part;
A first metal layer etching step of wet etching the first metal layer after the diffusion portion forming step;
A method of manufacturing a suspension substrate having
The intermediate member preparing step includes a resist pattern forming step of forming a resist pattern for forming the wiring layer,
A method for manufacturing a suspension substrate , wherein a resist pattern removing step for removing the resist pattern is performed before or after the diffusion portion forming step . A metal support substrate; an insulating layer formed on the metal support substrate; a first metal layer formed on the insulating layer and having a portion to be a first metal portion; and formed on the first metal portion. An intermediate member preparing step of preparing an intermediate member comprising a wiring layer having a metal component different from the first metal portion;
A diffusion part forming step of performing a heat treatment on the intermediate member to form a diffusion part formed by mutual diffusion of the metal components of the first metal part and the wiring layer;
A first metal layer etching step of wet etching the first metal layer after the diffusion portion forming step;
A method of manufacturing a suspension substrate having
The intermediate member preparing step includes a resist pattern forming step of forming a resist pattern for forming the wiring layer,
A method for manufacturing a suspension substrate , wherein a resist pattern removing step for removing the resist pattern is performed before or after the diffusion portion forming step . An insulating layer forming step of forming an insulating layer on the metal supporting substrate;
A first metal layer forming step of forming a first metal layer having a portion to be a first metal part on the insulating layer;
A resist pattern forming step for forming a resist pattern for forming a wiring layer on the first metal layer;
A second metal part forming step of forming a second metal part having a metal component different from the first metal part on the first metal part exposed from the resist pattern;
A wiring layer forming step of forming a wiring layer on the second metal part;
A resist pattern removing step for removing the resist pattern after the wiring layer forming step;
A first metal layer etching step of performing wet etching on the first metal layer after the resist pattern removing step;
After the second metal portion forming step, the wiring layer forming step, or the resist pattern removing step, and before the first metal layer etching step, the first metal portion and the second metal are formed by heat treatment. A method of manufacturing a suspension substrate, comprising: a diffusion part forming step of forming a diffusion part formed by mutual diffusion of metal components of a metal part. A suspension comprising the suspension substrate according to any one of claims 1 to 6. A suspension with an element, comprising: the suspension according to claim 10; and an element mounted in an element mounting region of the suspension. A hard disk drive comprising the element-equipped suspension according to claim 11.

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