JP5728837B2 - 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 having a conductor layer that functions as an electromagnetic wave shield.

  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.

  In particular, in suspension boards that have been increasing in speed in recent years, electromagnetic noise radiated from wiring to the outside (electromagnetic shielding), electromagnetic noise radiated from the outside to wiring (electromagnetic shielding), and wiring Therefore, it is required to cut off electromagnetic wave noise between them (prevention of crosstalk). In order to suppress the influence of such electromagnetic wave noise, a ground wire is provided in the vicinity of the wiring that is the transmission path of the electric signal, the wiring interval is widened, or the conductor layer (conductive layer is covered with the cover layer covering the wiring. A structure for forming a shield layer) is known. In addition, conventional techniques for suppressing the influence of electromagnetic noise can be broadly classified into two.

  The first prior art is a technique for suppressing crosstalk by stacking wirings vertically through insulating layers. For example, Patent Document 1 discloses a structure in which wirings are stacked vertically via an insulating layer, and a ground layer is disposed therebetween (FIG. 2 of Patent Document 1). Patent Document 2 discloses a structure in which wirings are stacked one above the other through insulating layers (FIG. 2 of Patent Document 2). Further, Patent Document 3 discloses a structure in which wirings are stacked one above the other through an insulating layer, and a ground layer is disposed beside the upper wiring (FIG. 2 (a) of Patent Document 3). Patent Document 4 discloses a structure in which a wiring layer is disposed on the same surface of an insulating layer, but a ground layer is disposed on the wiring via an insulating layer (see FIG. 4). 1). In this way, crosstalk can be suppressed by stacking wirings vertically via an insulating layer. However, in order to form such a laminated structure, it is necessary to significantly increase the number of steps as compared with the conventional case, and there is a disadvantage that the manufacturing cost increases.

  The second prior art is a technique in which a conductor layer is provided on the surface of a cover layer covering the wiring. For example, Patent Document 5 describes that a shield layer for conducting a cover layer and a metal support substrate is formed by a vacuum film forming method or a plating method (FIG. 1 of Patent Document 5). Patent Document 6 discloses a structure in which a wiring is surrounded by a ground layer through an insulating layer (FIG. 2 of Patent Document 6). Patent Document 7 discloses a structure in which an anisotropic conductive film is provided between the cover layer and the shield layer, and the anisotropic conductive film is connected to the ground layer exposed from the opening in the cover layer. (FIG. 1 of Patent Document 7).

  Further, although not intended to suppress electromagnetic wave noise, there are the following techniques for suppressing the influence of static electricity. For example, Patent Document 8 discloses that a semiconductive layer containing conductive particles is used for at least one of the insulating layer and the cover layer to prevent charging (FIG. 2 of Patent Document 8). Patent Document 9 discloses that an electrically conductive polymer is contained in an imide-based resin, and coating is performed on an insulating layer including a terminal portion to prevent charging (FIG. 2 of Patent Document 9).

  Further, in Patent Document 10, a head gimbal assembly having a transmission line for transmitting a signal to a recording assist element, in which a conductor wire connects an upper shield, a lower shield, and an upper shield and a lower shield. What is surrounded by a plurality of pillars is disclosed.

JP 2009-188080 A JP 2009-26909 A JP 2009-206379 A JP-A-8-264911 JP 2004-363281 A JP 2009-246092 A JP 2009-200113 A JP 2009-332548 A JP 2007-2134 A JP 2010-73297 A

  With the enhancement of the functionality of the suspension substrate, there is a demand for improved electromagnetic shielding properties. The present invention has been made in view of the above circumstances, and has as its main object to provide a suspension substrate having high electromagnetic shielding properties.

  In order to solve the above problems, in the present invention, a metal support substrate, an insulating layer formed on the metal support substrate, and a first wiring layer and a second wiring layer formed on the insulating layer. A suspension substrate having a wiring layer and a cover layer formed so as to cover the wiring pair, on the cover layer, and at a position overlapping the wiring pair in plan view. A conductor layer is formed, disposed so as to sandwich the wiring pair, and a via portion that penetrates the insulating layer and the cover layer and electrically connects the metal support substrate and the conductor layer is formed. A suspension substrate is provided.

  According to the present invention, a wiring pair is surrounded by a metal support substrate, a conductor layer, and a via portion, whereby a structure similar to that of a coaxial cable can be obtained and a suspension substrate having a high electromagnetic wave shielding property can be obtained. Furthermore, the suspension substrate of the present invention can be manufactured by, for example, a simple method of forming a conductor layer on a cover layer. Therefore, there is an advantage that it does not cause a significant increase in the number of processes.

  In the above invention, the via part is formed so as to penetrate the via part wiring layer, and the opening diameter of the via part wiring layer is larger than the opening diameter of the insulating layer at the position where the via part penetrates. Small is preferable. This is because adhesion in the thickness direction can be improved.

  In the said invention, it is preferable that the said via part is formed in the floating island shape. This is because the degree of freedom of arrangement of the via portion is higher.

  In the said invention, it is preferable that the said via part is formed in linear form. This is because the electromagnetic wave shielding property can be further enhanced.

  Further, in the present invention, a metal support substrate, an insulating layer formed on the metal support substrate, a wiring pair formed on the insulating layer and composed of a first wiring layer and a second wiring layer, A laminate having a cover layer formed so as to cover the wire pair, and a via portion that is disposed so as to sandwich the wire pair, penetrates the insulating layer and the cover layer, and contacts the metal supporting substrate. A laminated body preparation step to be prepared, and a conductor layer forming step of forming a conductor layer in contact with the via portion at a position on the cover layer and overlapping the wire pair in plan view. A suspension substrate manufacturing method is provided.

  According to the present invention, the wiring pair is surrounded by the metal support substrate, the conductor layer, and the via portion, whereby a structure similar to that of the coaxial cable can be obtained, and a suspension substrate having a high electromagnetic shielding property can be obtained. Furthermore, according to the present invention, a suspension substrate having a high electromagnetic shielding property can be obtained by a simple method of forming the conductor layer on the cover layer of the laminate.

  In the above invention, the via part is formed so as to penetrate the via part wiring layer, and the opening diameter of the via part wiring layer is larger than the opening diameter of the insulating layer at the position where the via part penetrates. Small is preferable. This is because adhesion in the thickness direction can be improved.

  In the said invention, it is preferable in the said laminated body preparation process to form the said via part by the electroplating method by the electric power feeding from the said metal support substrate. This is because the via portion penetrating the insulating layer and the cover layer can be formed with good adhesion.

  In the said invention, it is preferable to form the said conductor layer by sputtering method in the said conductor layer formation process.

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

  According to the present invention, by using the suspension substrate described above, a suspension with high electromagnetic shielding properties 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 a high electromagnetic shielding property 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 functionality can be obtained by using the above-described suspension with an element.

  In the present invention, there is an effect that a suspension substrate having a high electromagnetic wave shielding property can be provided.

It is a schematic diagram showing an example of a general suspension substrate. It is a schematic diagram which shows an example of the board | substrate for suspensions of this invention. It is a schematic sectional drawing which illustrates a via part in the present invention. It is a schematic diagram which shows the other example of the board | substrate for suspensions of this invention. It is a schematic diagram which shows the other example of the board | substrate for suspensions of this invention. It is a schematic plan view explaining the conductor layer in this invention. It is a schematic sectional drawing which shows an example of the manufacturing method of the board | substrate for suspensions of this invention. It is a schematic sectional drawing which shows an example of the formation method of the laminated body in this invention. 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. 4 is a measurement result of differential impedance with respect to a suspension substrate obtained in Example 2 and Comparative Example 1.

  The 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. First, the suspension substrate of the present invention will be described. The suspension substrate of the present invention includes a metal support substrate, an insulating layer formed on the metal support substrate, and a wiring pair formed on the insulating layer and including a first wiring layer and a second wiring layer. A suspension layer having a cover layer formed so as to cover the wire pair, and a conductor layer is formed on the cover layer and at a position overlapping the wire pair in plan view. And a via portion that is disposed so as to sandwich the wiring pair, penetrates the insulating layer and the cover layer, and electrically connects the metal support substrate and the conductor layer. is there.

  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 cross-sectional view taken along line AA in 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 wiring pairs. Similarly, the wiring layer 13c and the wiring layer 13d are wiring pairs. One of these wire pairs is a write wire pair, and the other is a read wire pair. Each of these wiring pairs is preferably a differential wiring having a characteristic impedance (differential impedance) defined in the concept of a distributed constant circuit. 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. And a cover layer 4 covering the wiring layer 3.

  FIG. 2 is a schematic view showing an example of the suspension substrate of the present invention. 2A is a schematic plan view of the suspension substrate observed from the conductor layer side, and FIG. 2B is a schematic plan view of the suspension substrate observed from the metal support substrate side. These are AA sectional drawing of Fig.2 (a). The suspension substrate shown in FIG. 2 (c) includes a metal support substrate 1, an insulating layer 2 formed on the metal support substrate 1, and an insulating layer 2, and a first wiring layer 3a and a second wiring layer. The wiring pair 3A is composed of 3b and the cover layer 4 is formed so as to cover the wiring pair 3A. A conductor layer 5 is formed on the cover layer 4 and at a position overlapping the wiring pair 3A in plan view. Furthermore, a via portion 6 is formed so as to sandwich the wiring pair 3 </ b> A, penetrates the insulating layer 2 and the cover layer 4, and electrically connects the metal support substrate 1 and the conductor layer 5. Thereby, the wiring pair 3A can be configured to be surrounded by the metal support substrate 1, the conductor layer 5, and the via portion 6, and can be configured similar to a coaxial cable.

  FIG. 2C shows a mode in which the via portion 6 is formed so as to penetrate the via portion wiring layer 3e. Moreover, in FIG.2 (b), the metal support substrate 1 has the bridge part 1a and the opening part, and forms the micro window. By forming the micro window, it is possible to reduce transmission loss of electric signals (particularly high frequency signals). Moreover, the metal supporting board 1 functions as a ground layer, for example.

  As described above, according to the present invention, the wiring pair is surrounded by the metal support substrate, the conductor layer, and the via portion, whereby a structure similar to that of the coaxial cable can be obtained, and the suspension substrate having a high electromagnetic shielding property Can do. In particular, the suspension substrate of the present invention has an advantage that it is suitable for miniaturization because it can enclose the wiring pair using a via portion having a small shape. Furthermore, it can be said that it is suitable for miniaturization from the viewpoint that the degree of freedom of arrangement of via portions is high.

  Further, in the technique of providing a conductor layer on the surface of the cover layer covering the wiring, the manufacturing process tends to be complicated. For example, in the manufacturing method described in FIG. 1 of Patent Document 5, it is necessary to partially etch the shield layer 6. Moreover, in the manufacturing method described in FIGS. 3 to 5 of Patent Document 6, many steps are required to form the ground layer. On the other hand, the suspension substrate of the present invention can be manufactured by, for example, a simple method of forming a conductor layer on a cover layer. Therefore, there is an advantage that it does not cause a significant increase in the number of processes.

  Furthermore, according to the present invention, since capacitive coupling can be formed between the wiring pair and the conductor layer, impedance can be reduced. In addition, according to the present invention, since the conductor layer is electrically connected to the metal support substrate, there is an advantage that it is possible to prevent problems caused by static electricity (for example, destruction of elements due to static electricity). Furthermore, according to the present invention, it is also possible to reduce noise when transferring a microwave signal used in heat-assisted recording. That is, the wiring pair in the present invention may be a wiring pair for transmitting a signal to the recording assist element.

Further, Patent Document 7 described above discloses a structure in which an anisotropic conductive film is provided between a cover layer and a shield layer. However, if an anisotropic conductive film is entirely provided between the cover layer and the shield layer, the adhesion between the cover layer (for example, resin) and the anisotropic conductive film (for example, resin) may be reduced. There is. On the other hand, in this invention, since an anisotropic conductive film is not provided in the whole surface, the fall of adhesiveness can be prevented.
Hereinafter, the suspension substrate of the present invention will be described separately for the suspension substrate member and the suspension substrate configuration.

1. First, members of the suspension substrate of the present invention will be described. The suspension substrate of the present invention has a metal support substrate, an insulating layer, a first wiring, a second wiring, a cover layer, a conductor layer, and a via part.

  The metal support substrate in the present invention 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. Although the thickness of a metal supporting board changes with kinds of the material, it is preferable in the range of 5 micrometers-30 micrometers, for example, and it is more preferable that it is in the range of 10 micrometers-20 micrometers. As for SUS, the minimum thickness of what can be rolled is about 15 μm. Considering the future demand for thinning, the above range is preferable.

  The insulating layer in the present invention is formed on a 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 15 μm. This is because, within the above range, a sufficiently low impedance can be achieved and good insulation performance (reduction of high-frequency loss) can be obtained.

  The first wiring layer and the second wiring layer in the present invention are formed on the insulating layer. The first wiring layer and the second wiring layer constitute a wiring pair. The wiring pair is preferably a differential wiring. Furthermore, the wiring pair may be a write wiring pair or a read wiring pair. Further, as described above, the wire pair may be a wire pair for transmitting a signal to the recording assist element. On the other hand, in the present invention, it is preferable that a wiring pair composed of a third wiring layer and a fourth wiring layer is formed on the insulating layer. Further, when the wiring pair is a write wiring pair or a read wiring pair, the wiring pair is also preferably a differential wiring. In addition, when the wiring pair composed of the third wiring layer and the fourth wiring layer is a wiring pair having different functions (for example, a combination of a single wiring layer and a ground wiring layer), a differential wiring is used. There is no need. Examples of the material for the wiring layer include metals, and copper (Cu) is preferable among them. This is because the conductivity is high. The material of the wiring layer may be electrolytic copper or rolled copper. 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 5 μm to 12 μm. If the wiring layer is thin, it is easy to obtain a fine pitch wiring layer.

  The cover layer in the present invention is formed so as to cover the wiring pair. By providing the cover layer, it is possible to prevent deterioration (for example, corrosion) of the wiring pair. 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.

  The conductor layer in the present invention is formed on the cover layer and at a position overlapping the wiring pair in plan view. The material of the conductor layer is not particularly limited as long as it has electrical conductivity, and examples thereof include metals. Specifically, Pt, Au, Ag, Pd, Cu, Cr, Ni , Ti, Ta, and alloys containing one or more of these metals can be given, among which Ti, Ni, and Cr are preferable, and Ni and Cr are particularly preferable. It is because it can be set as a conductor layer with favorable corrosion resistance. The thickness of the conductor layer is not particularly limited as long as a desired electromagnetic wave shielding effect can be obtained, but it is preferably, for example, 30 nm or more, more preferably 100 nm or more, and 300 nm or more. Further preferred. This is because it is effective in reducing the impedance of the wiring layer. Further, if the thickness of the conductor layer is too thin, scratch resistance may be lowered. Similarly, the thickness of the conductor layer is preferably, for example, 10 μm or less, more preferably 6 μm or less, and further preferably 4 μm or less. This is because if the thickness of the conductor layer is too thick, the rigidity may become too high.

  The via portion in the present invention is disposed so as to sandwich the wiring pair, penetrates the insulating layer and the cover layer, and electrically connects the metal support substrate and the conductor layer. The material of the via portion is not particularly limited as long as it has conductivity, and examples thereof include metals. Specifically, nickel (Ni), silver (Ag), gold (Au) can be cited. , Copper (Cu), and an alloy containing one or more of these metals. It is because it is excellent in electroconductivity and corrosion resistance. Moreover, it is preferable that the via | veer part in this invention is formed by the plating method. This is because a via portion having good adhesion can be obtained.

2. Next, the configuration of the suspension substrate of the present invention will be described. One feature of the suspension substrate of the present invention is that the suspension substrate is disposed so as to sandwich the wiring pair, and has a via portion that penetrates the insulating layer and the cover layer and electrically connects the metal support substrate and the conductor layer.

In the present invention, as shown in FIG. 3A, the via portion 6 is preferably formed so as to penetrate the via portion wiring layer 3e. This is because by providing the via part wiring layer 3e, the adhesion of the via part can be improved. Further, in the present invention, the opening diameter W ₁ of the via portion wiring layer 3e is preferably via part 6 is smaller than the opening diameter W ₂ of the insulating layer 2 in the position penetrating. This is because the adhesiveness in the thickness direction can be improved by adjusting the opening diameter in this way.

Here, the opening value of the diameter _{W 1} of the via portion wiring layer 3e, for example in the range of 30Myuemu～150myuemu, preferably in the range of inter alia 40 m to 100 m. This is because if the value of the opening diameter W ₁ is too small, the mechanical strength of the via portion may be lowered, and if the value of the opening diameter W ₁ is too large, miniaturization may be difficult. Further, the opening value of the diameter _{W 2} of the insulating layer 2, for example in the range of 30Myuemu～150myuemu, preferably in the range of inter alia 50 .mu.m to 100 .mu.m. When the value of the opening diameter W ₂ is too small, there may not be sufficient contact with the metal supporting board, the value of the opening diameter W ₂ is too large, the fine may become difficult. The difference between both the opening diameter _(W 2 -W ₁₎ is preferably, for example at 5μm or more, and more preferably in the range of 5Myuemu～40myuemu.

Also, if the width of the top portion of the via portion 6 was set to _{W 3,} the value of _{W 3} being, for example, is preferably in the range of 45Myuemu～125myuemu, and more preferably in a range of 65Myuemu～100myuemu. The top of the via 6 is preferably defined by the opening of the cover layer 4. _Further, W 3 -W ₁ is preferably, for example in the range of 15Myuemu～20myuemu. Further, the end portion of the via portion, and the distance between the end portion of the wiring layer was _{W 4,} the value of _{W 4} is, for example, preferably in the range of 15Myuemu～200myuemu, within the 30μm~100μm More preferably. When the value of W ₄ is too small, the metal supporting board, and a shield structure comprising a conductive layer and the via portion, it increases the capacitive coupling between the wiring layers, the electromagnetic wave shielding property may be deteriorated. On the other hand, when the value of W ₄ is too large, the design freedom may be decreased.

  On the other hand, in the present invention, as shown in FIG. 3B, the via portion 6 may penetrate only the insulating layer 2 and the cover layer 4. Thereby, compared with the case where the wiring layer 3e for via | veer part is formed, the via | veer part 6 can be reduced in size and it can be set as the board | substrate for suspension suitable for refinement | miniaturization.

  Moreover, the position of the top part of the via part in the present invention is not particularly limited as long as it is a position where the metal supporting board and the conductor layer can be electrically connected. The position of the top portion of the via portion may be lower, the same or higher than the position of the top portion of the cover layer, but is preferably the same or higher. This is because it is easy to make an electrical connection to the conductor layer. Furthermore, the position of the top of the via part may be lower, the same or higher than the position of the top of the conductor layer.

  In addition, as shown in FIG. 2, the via portion 6 in the present invention is preferably formed in a floating island shape (dot shape). This is because the degree of freedom of arrangement of the via portion is higher. The plan view shape of the floating island-shaped via portion is not particularly limited, and any shape can be adopted. Specific examples include a circular shape, an elliptical shape, a polygonal shape, a cross shape, and a comb shape. Further, at least one via portion 6 in the present invention may be disposed at both ends of the wiring pair 3A, but from the viewpoint of improving the electromagnetic wave shielding property, as shown in FIG. It is preferable that a plurality of via portions are disposed at both ends of the pair 3A. Further, the shielding effect can be stabilized by arranging the via portions evenly.

  FIG. 4 is a schematic view showing another example of the suspension substrate according to the present invention. FIG. 4A is a schematic plan view of the suspension substrate observed from the conductor layer side, and FIG. These are AA sectional drawing of Fig.4 (a). In FIG. 4A, the conductor layer is not shown for convenience. As shown in FIG. 4, the via portion 6 in the present invention is preferably formed in a linear shape. This is because the electromagnetic wave shielding property can be further enhanced. In particular, in the present invention, as shown in FIG. 4A, it is preferable that a linear via portion 6 is formed along the wiring pair 3A. The linear shape in the present invention includes a linear shape, a curved shape, and a combination thereof.

  FIG. 5 is a schematic view showing another example of the suspension substrate of the present invention, and FIG. 5 (a) is a schematic plan view of the suspension substrate observed from the conductor layer side, and FIG. These are AA sectional drawing of Fig.5 (a). As shown in FIG. 5, in the present invention, not only the first wiring pair 3A composed of the first wiring layer 3a and the second wiring layer 3b but also the third wiring layer 3c and the fourth wiring layer 3d. A similar via portion 6 and conductor layer 5 may be formed in the second wiring pair 3 </ b> B composed of Thereby, for example, the electromagnetic wave shielding property can be enhanced with respect to both the read wiring layer and the write wiring layer.

  In FIG. 5, the via portion 6 is formed between the first wiring pair 3A and the second wiring pair 3B. For example, in the region where the first wiring pair 3A and the second wiring pair 3B are close to each other. The central via portion 6 may not be formed. In FIG. 5, the conductor layer 5 is formed on the entire surface of the cover layer 4. However, in the present invention, it is only necessary that at least the conductor layer 5 is formed at a position overlapping the wiring pair in plan view. This is because if the conductor layer is formed in this way, electromagnetic wave shielding can be imparted to the wiring pair.

  In addition, as shown in FIG. 6, the total length of the conductor layer 5 corresponding to the length direction of the wiring pair 3A is L. This L means the length when the conductor layer 5 is formed continuously, and when the conductor layer 5 is formed intermittently, the total length of the conductor layer 5 in each piece. Means. Although the value of L is not specifically limited, For example, it is preferable that it is 5 mm or more, and it is more preferable that it is 10 mm or more. Further, the ratio of L to the total length of the wiring pair 3A is, for example, preferably 50% or more, more preferably 70% or more, and further preferably 95% or more. This is because the larger the ratio of L, the higher the electromagnetic shielding properties. Further, in the impedance design, it is preferable to adjust the impedance in a region where the wiring pair is linearly formed with the same thickness. This is because it is easy to design impedance. In the present invention, a conductor layer is preferably formed in such a region (impedance adjustment region).

B. Next, a method for manufacturing a suspension substrate according to the present invention will be described. The suspension substrate manufacturing method of the present invention includes a metal support substrate, an insulating layer formed on the metal support substrate, and a first wiring layer and a second wiring layer formed on the insulating layer. A wiring pair, a cover layer formed so as to cover the wiring pair, and a via portion that is disposed so as to sandwich the wiring pair, penetrates the insulating layer and the cover layer, and contacts the metal support substrate. A laminated body preparing step of preparing a laminated body having, and a conductor layer forming step of forming a conductive layer on the cover layer and in contact with the via portion at a position overlapping the wiring pair in plan view; It is characterized by having.

  FIG. 7 is a schematic cross-sectional view showing an example of a method for manufacturing a suspension substrate according to the present invention. FIG. 7 corresponds to the AA cross-sectional view of FIG. 5A, similarly to FIG. 5B described above. In FIG. 7, the laminated body 21 is prepared first (FIG. 7 (a)). The laminate 21 includes a metal support substrate 1, an insulating layer 2 formed on the metal support substrate 1, and a first wiring layer 3a and a second wiring layer 3b formed on the insulating layer 2. The first wiring pair 3A, the second wiring pair 3B composed of the third wiring layer 3c and the fourth wiring layer 3d, and the cover layer formed so as to cover the first wiring pair 3A and the second wiring pair 3B 4 and a via portion 6 that is disposed so as to sandwich the first wiring pair 3A and the second wiring pair 3B, penetrates the insulating layer 2 and the cover layer 4, and contacts the metal support substrate 1. Next, a conductor layer 5 that is in contact with the via portion 6 is formed on the laminated body on the cover layer 4 and at a position overlapping the first wiring pair 3A and the second wiring pair 3B in plan view. (FIG. 7B). Thereby, the suspension substrate 20 can be obtained.

According to the present invention, the wiring pair is surrounded by the metal support substrate, the conductor layer, and the via portion, whereby a structure similar to that of the coaxial cable can be obtained, and a suspension substrate having a high electromagnetic shielding property can be obtained. Furthermore, according to the present invention, a suspension substrate having a high electromagnetic shielding property can be obtained by a simple method of forming the conductor layer on the cover layer of the laminate.
Hereinafter, the manufacturing method of the suspension substrate according to the present invention will be described step by step.

1. Laminated body preparation process The laminated body preparation process in this invention is a process of preparing the laminated body mentioned above. The laminated body in this invention is a member before forming a conductor layer, The formation method is not specifically limited, Arbitrary methods are possible. As will be described later, a laminate may be formed using a three-layer material, or a laminate may be formed by a so-called additive method.

  FIG. 8 is a schematic cross-sectional view showing an example of a method for forming a laminate in the present invention. In FIG. 8, first, a laminated member (three-layer material) having a metal supporting board 1X, an insulating layer 2X formed on the metal supporting board 1X, and a wiring layer 3X formed on the insulating layer 2X is prepared. (FIG. 8A). Next, a resist pattern is formed on both surfaces of the metal support substrate 1X and the wiring layer 3X using DFR, and the metal support layer 1X and the wiring layer 3X exposed from the resist pattern are wet-etched. Thus, the first wiring layer 3a, the second wiring layer 3b, the third wiring layer 3c, the fourth wiring layer 3d, and the via portion wiring layer 3e are formed (FIG. 8B). In this step, the metal support substrate 1X located under the first wiring layer 3a, the second wiring layer 3b, the third wiring layer 3c, and the fourth wiring layer 3d is removed.

  Thereafter, the cover layer 4 covering the wiring layers 3a to 3e is formed (FIG. 8C). At this time, an opening of the cover layer 4 is provided at a position where the via portion is formed. Next, the insulating layer 2X is wet etched to form the insulating layer 2 (FIG. 8D). At this time, an opening of the insulating layer 2 is provided at a position where the via portion is formed. Next, the via part 6 penetrating the insulating layer 2, the via part wiring layer 3e, and the cover layer 4 is formed by an electrolytic plating method by feeding from the metal support substrate 1X (FIG. 8D). At this time, it is preferable to form the metal support substrate 1 by performing external processing of the metal support substrate 1X. Thereby, the laminated body 21 can be obtained. 8D shows the metal support substrate after the outer shape processing, but in the present invention, the outer shape processing of the metal support substrate is performed after the conductor layer forming step described later. May be.

  In FIG. 8, various types of wet etching are performed. It is preferable to select an etchant used for wet etching in consideration of the characteristics of each material. For example, when SUS is used for the metal support substrate and when copper is used for the wiring layer, for example, an iron chloride based etchant can be used as the etchant. Further, when a polyimide resin is used for the insulating layer and the cover layer, for example, an alkaline etching solution can be used as the etching solution. Moreover, in each process mentioned above, it is preferable to form a resist pattern suitably as needed.

  In particular, in the present invention, it is preferable to form a via part by an electrolytic plating method by feeding from a metal support substrate (for example, FIG. 8D described above). This is because the via portion penetrating the insulating layer and the cover layer can be formed with good adhesion.

2. Conductive layer forming step Next, the conductive layer forming step in the present invention will be described. The conductor layer forming step in the present invention is a step of forming a conductor layer in contact with the via portion on the cover layer and at a position overlapping the wiring pair in plan view.

  The method for forming the conductor layer is not particularly limited as long as a desired conductor layer can be obtained. An example of the method for forming the conductor layer is a vapor deposition method, which may be a PVD (physical vapor deposition) method or a CVD (chemical vapor deposition) method, but the PVD method is preferred. Furthermore, examples of the PVD method include a sputtering method, a resistance heating vapor deposition method, an electron beam vapor deposition method, an ion plating method, and the like, and among these, the sputtering method is preferable. In the present invention, the conductor layer may be formed only by the vapor deposition method, or the conductor layer may be formed by combining the vapor deposition method and the electrolytic plating method. In the latter case, a seed layer is usually formed by a vapor deposition method, and an electrolytic plating method is performed by supplying power from the seed layer. In the present invention, the conductor layer may be formed only by the electroless plating method, or the conductor layer may be formed by combining the electroless plating method and the electrolytic plating method.

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 suspension substrate described above, a suspension with high electromagnetic shielding properties can be obtained.

  FIG. 9 is a schematic plan view showing an example of the suspension of the present invention. A suspension 40 shown in FIG. 9 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 “B. 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 a high electromagnetic shielding property can be obtained.

  FIG. 10 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. 10 includes the suspension 40 described above and an element 41 mounted in 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 functionality can be obtained by using the above-described suspension with an element.

  FIG. 11 is a schematic plan view showing an example of the hard disk drive of the present invention. A hard disk drive 60 shown in FIG. 11 includes the above-described suspension 50 with an element, a disk 51 on which data is written and read by the suspension 50 with an element, 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, a laminated member (three-layer material) having SUS304 (metal support substrate) having a thickness of 18 μm, a polyimide resin layer (insulating layer) having a thickness of 10 μm, and an electrolytic copper layer (wiring layer) having a thickness of 5 μm was prepared (FIG. 8 (a)). Next, a dry film is used so that a jig hole whose positional accuracy is important on the SUS side and a wiring layer (first wiring layer to fourth wiring layer, wiring layer for via part) can be formed on the electrolytic copper side. At the same time, patterning was performed to form a patterned resist. Then, it etched using the ferric chloride liquid, and resist stripping was performed after the etching (FIG.8 (b)).

  Next, a polyimide precursor solution is coated on the patterned wiring layer with a die coater, dried, resist plate-making, etched at the same time as the polyimide precursor film, and then cured by heating in a nitrogen atmosphere. (Imidization) to form a cover layer (FIG. 8C). The cover layer was formed so as to cover the wiring layer, and the thickness of the cover layer formed on the wiring layer was 10 μm. Next, wet etching of the insulating layer was performed (FIG. 8D). Next, a via portion was formed by an electrolytic plating method by feeding from a metal support substrate. Next, the metal support substrate was wet etched to obtain a laminate (FIG. 8D).

  Thereafter, a two-layer mixed conductor layer (thickness: 0.3 μm) made of Ni and Cr was formed on the cover layer of the laminate by sputtering (FIG. 7B). As a result, the suspension substrate of the present invention was obtained.

[Example 2]
A suspension substrate was obtained in the same manner as in Example 1 except that the type of the conductor layer was changed to Pt.

[Comparative Example 1]
A suspension substrate was obtained in the same manner as in Example 2 except that the conductor layer was not formed.

[Evaluation]
The differential impedance of the suspension substrate obtained in Example 2 and Comparative Example 1 was measured. The result is shown in FIG. As shown in FIG. 12, the differential impedance was reduced from 90Ω to 60Ω by forming the conductor layer. This is because a capacitive coupling could be formed between the wiring pair and the conductor layer.

  DESCRIPTION OF SYMBOLS 1 ... Metal support substrate, 2 ... Insulating layer, 3 ... Wiring layer, 3a ... First wiring layer, 3b ... Second wiring layer, 3c ... Third wiring layer, 3d ... Fourth wiring layer, 3e ... Wiring for via part Layer, 4 ... cover layer, 5 ... conductor layer, 6 ... via portion, 11 ... element mounting region, 12 ... external circuit board connection region, 13 ... wiring layer, 20 ... suspension substrate, 21 ... laminate

Claims (9)

A metal supporting board, an insulating layer formed on the metal supporting board, a wiring pair formed on the insulating layer and composed of a first wiring layer and a second wiring layer, and so as to cover the wiring pair A suspension substrate having a formed cover layer,
A conductor layer is formed on the cover layer and at a position overlapping the wire pair in plan view,
A via portion is formed so as to sandwich the wiring pair, penetrates the insulating layer and the cover layer, and electrically connects the metal support substrate and the conductor layer ,
The via part is formed so as to penetrate the via part wiring layer,
The suspension substrate , wherein an opening diameter of the via portion wiring layer is smaller than an opening diameter of the insulating layer at a position where the via portion penetrates . The suspension substrate according to claim 1, wherein the via portion is formed in a floating island shape. The suspension substrate according to claim 1, wherein the via portion is formed in a linear shape. A metal supporting board, an insulating layer formed on the metal supporting board, a wiring pair formed on the insulating layer and composed of a first wiring layer and a second wiring layer, and so as to cover the wiring pair a cover layer formed, is disposed so as to sandwich the wire pairs, said insulating layer and through said cover layer, have a and the via in contact with the metal supporting board, the via portion, a via part A laminated body preparing step of preparing a laminated body that is formed so as to penetrate the wiring layer, and the opening diameter of the wiring layer for the via part is smaller than the opening diameter of the insulating layer at the position where the via part penetrates ;
A conductor layer forming step for forming a conductor layer in contact with the via portion on the cover layer and at a position overlapping the wiring pair in plan view;
A method for manufacturing a suspension substrate, comprising: 5. The method for manufacturing a suspension substrate according to claim 4 , wherein, in the layered body preparation step, the via portion is formed by an electrolytic plating method using power feeding from the metal support substrate. 6. The method for manufacturing a suspension substrate according to claim 4 , wherein, in the conductor layer forming step, the conductor layer is formed by a sputtering method. A suspension comprising the suspension substrate according to any one of claims 1 to 3 . A suspension with an element comprising the suspension according to claim 7 and an element mounted in an element mounting region of the suspension. A hard disk drive comprising the suspension with an element according to claim 8 .

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