JP4962392B2 - Suspension substrate manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a suspension substrate used in a hard disk drive (HDD) or the like, and more particularly to a method for manufacturing a suspension substrate that can provide a suspension substrate with low rigidity.

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

  Recently, the demand for HDDs installed in various small devices such as portable applications has increased, and along with this, disks for recording information have become smaller in size and higher in recording density. . In order to read and write data to tracks on this disk with a reduced diameter, it is necessary to rotate the disk slowly, and the relative speed (circumferential speed) of the disk to the magnetic head is low, so that Since the substrate needs to approach the disk with a weak force, it is necessary to reduce the rigidity of the suspension substrate.

  As a method of forming a low-rigidity suspension substrate, a laminated body in which a metal substrate, an insulating layer, a seed layer, and a metal plating layer are arranged in this order (see, for example, Patent Documents 1 and 2) is used. Etching methods are known. However, when etching is performed using the above laminate, there is a problem that the laminate during processing is deformed during conveyance. That is, conventionally, the metal substrate is etched at an early stage and the outer shape of the metal substrate is processed, but this outer shape processing significantly reduces the rigidity of the laminated body in the middle of processing, leading to the subsequent insulating layer etching process. It becomes easy to deform while moving. In addition, the post-processing such as the protective plating portion forming step for protecting the wiring pattern layer and the cover layer forming step is affected in the same manner, and the deformation rate of the laminate during processing is further increased. As described above, when the rigidity of the suspension member is reduced, there arises a problem that the yield of the product is deteriorated.

  In Patent Document 3, using a laminate composed of a spring metal layer / insulating layer / conductive layer, a step of forming a jig hole in the spring metal layer, and a step of processing the outer shape of the spring metal layer A method of manufacturing a magnetic head suspension is disclosed in which is a separate process. However, the laminated body used is not specifically described, and the suspension substrate may not be sufficiently reduced in rigidity. Patent Document 4 discloses a method for manufacturing a suspension for a hard disk head by a so-called additive method.

JP 2006-248142 A JP 2005-285178 A JP 2006-209853 A JP 2000-48510 A

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a method for manufacturing a suspension substrate that can manufacture a suspension substrate having a low rigidity with a high yield.

  In order to solve the above-described problem, in the present invention, a cover material is used for a laminate in which a metal substrate, an insulating layer, a seed layer, and a wiring pattern layer are laminated in this order, and the surface of the wiring pattern layer is formed. A cover layer forming step for forming a cover layer having a wiring pattern layer exposed opening partly exposed, and an insulating layer etching step for etching the insulating layer after the cover layer is formed. A method for manufacturing a suspension substrate is provided.

  According to the present invention, the thickness of the cover layer in the suspension substrate can be made uniform. As a result, the cover layer can be easily thinned, and the suspension substrate manufactured by the manufacturing method of the present invention can be reduced in weight.

In the above invention, further, a laminate preparation step of preparing a laminate in which a metal substrate, an insulating layer, a seed layer, and a metal plating layer are arranged in this order; and a surface of the metal substrate and a surface of the metal plating layer, Forming a hole in the metal substrate by forming a patterned resist and performing etching, and processing the metal plating layer into a wiring pattern layer; preferable.
This is because a low-rigidity suspension substrate can be obtained by using the above laminate. Further, in the first metal etching step, jig holes and punch holes are formed in the metal substrate, but most of the metal substrate is not etched. For this reason, it is possible to perform etching or the like of the insulating layer in a state where the rigidity of the laminated body is maintained high, and it is possible to suppress deformation of the laminated body in the middle of processing during conveyance between processes.

  In the said invention, it is preferable that the said cover material is a liquid cover material. This is because the film thickness of the cover layer in the suspension substrate can be made more uniform. In addition, since the cover layer can be made thin, the suspension substrate can be made lightweight.

  In the said invention, it is preferable that the difference of the maximum film thickness part and minimum film thickness part of the said metal plating layer is 2 micrometers or less. This is because a wiring pattern layer having a uniform film thickness can be obtained by etching the metal plating layer. When the wiring pattern layer is formed by the additive method, the thickness of the wiring pattern layer varies greatly, and it becomes difficult to obtain a pattern forming body having a desired rigidity.

  The difference between the maximum film thickness portion and the minimum film thickness portion on the wiring pattern layer of the cover layer is preferably 1 μm or less. Since the difference between the maximum film thickness portion and the minimum film thickness portion on the wiring pattern layer of the cover layer is 1 μm or less, the cover layer can be easily thinned, and the suspension substrate can be reduced in weight. Because it can be done.

  The present invention relates to a wiring pattern comprising a metal substrate, an insulating layer formed on the metal substrate, a seed layer formed on the insulating layer, and a metal plating layer formed in a pattern on the seed layer. And a difference between a maximum film thickness portion and a minimum film thickness portion of the wiring pattern layer is 2 μm or less.

  According to the present invention, since the difference between the maximum film thickness portion and the minimum film thickness portion of the wiring pattern layer is 2 μm or less, the wiring pattern layer can be easily thinned and lightweight. Can do.

In the above invention, the cover layer has a cover layer formed on the wiring pattern layer using a cover material and having a wiring pattern layer exposed opening in which a part of the surface of the wiring pattern layer is exposed. The difference between the maximum film thickness portion and the minimum film thickness portion on the pattern layer is preferably 1 μm or less.
Since the difference between the maximum film thickness portion and the minimum film thickness portion on the wiring pattern layer of the cover layer is 1 μm or less, the cover layer can be easily thinned and lightweight. It is.

  The present invention provides a suspension including the suspension substrate.

  According to the present invention, since the suspension substrate is included, the rigidity and weight can be reduced.

  The present invention provides a suspension with a head comprising the suspension and a magnetic head slider mounted on the suspension.

  According to the present invention, since the suspension is included, it is possible to achieve low rigidity and light weight.

  The present invention provides a hard disk drive including the suspension with a head.

  According to the present invention, since the suspension with a head is included, the power consumption can be reduced.

  In the present invention, there is an effect that a low-rigidity suspension substrate can be manufactured with a high yield.

The present invention relates to a method for manufacturing a suspension substrate, a suspension substrate, a suspension using the suspension substrate, a suspension with a head, and a hard disk drive.
Hereinafter, a method for manufacturing a suspension substrate, a suspension substrate, a suspension, a suspension with a head, and a hard disk drive according to the present invention will be described in detail.

A. First, a method for manufacturing a suspension substrate according to the present invention will be described. The method for manufacturing a suspension substrate according to the present invention includes a laminate preparation step of preparing a laminate in which a metal substrate, an insulating layer, a seed layer, and a metal plating layer are arranged in this order, and a surface of the metal substrate and the metal plating layer. Forming a pattern resist on the surface and performing etching to form a jig hole in the metal substrate, and processing the metal plating layer into a wiring pattern layer; and It is characterized by having.

  According to the present invention, a suspension substrate having a low rigidity can be obtained by using the above laminate. In the first metal etching step, jig holes and punch holes are formed in the metal substrate, but most of the metal substrate is not etched. Therefore, the insulating layer can be etched in a state where the rigidity of the laminated body is maintained high, and deformation of the laminated body during processing can be suppressed during conveyance between the processes. The suspension substrate obtained by the present invention can be used for a magnetic head suspension of a hard disk drive (HDD), for example.

  Next, a method for manufacturing a suspension substrate according to the present invention will be described with reference to the drawings. 1 and 2 are explanatory views for explaining an example of a method for manufacturing a suspension substrate according to the present invention. In the present invention, first, as shown in FIG. 1A, a laminate 10 in which a metal substrate 1, an insulating layer 2, a seed layer 3, and a metal plating layer 4 are arranged in this order is prepared (laminate preparation step). ). Here, a laminate 10 having SUS as the metal substrate 1, polyimide as the insulating layer 2, Ni—Cr—Cu sputtering layer as the seed layer 3, and Cu plating layer as the metal plating layer 4 is provided. prepare.

  Next, a resist for metal etching is made on the laminate 10. Specifically, a resist layer for metal etching is provided on both surfaces of the laminate 10, and resists 11 and 12 patterned as shown in FIG. 1B are formed by photolithography. In this case, the resist 11 is formed on the wiring side with a pattern corresponding to the target wiring pattern layer, and the resist 12 is formed on the substrate side with a pattern excluding the jig hole portion. Further, the resist 12 is formed so as to remove the flying lead portion in addition to the jig hole.

  Then, as shown in FIG. 1C, the metal substrate 1 and the metal plating layer 4 are etched using a chemical etching solution, and the resists 11 and 12 are peeled off. Thereby, the wiring pattern layer 4a is formed from the metal plating layer 4, and the jig hole 1a is formed in the metal substrate 1 (first metal etching step). In the figure, 1b is a hole for forming a flying lead portion.

  Next, as shown in FIG. 1D, a cover layer 5 is formed from above the wiring pattern layer 4a using a liquid cover material (cover layer forming step). At this time, the cover layer 5 is formed so that a part of the surface of the wiring pattern layer 4a is exposed, and a protective plating portion described later is formed on the exposed portion.

  Next, a resist for etching the insulating layer 2 is made. Specifically, a resist layer for polyimide etching is provided on both surfaces of the laminate 10, and resists 13 and 14 patterned as shown in FIG. 1E are formed by photolithography. In this case, a resist 13 is formed on the wiring side so as to cover the wiring pattern layer 4a and the cover layer 5, and a resist 14 is formed on the substrate side so as to exclude the corresponding portion of the hole 1b of the flying lead portion. .

  Then, as shown in FIG. 1F, the insulating layer 2 is etched using an organic alkaline solution as an etching solution, and the resists 13 and 14 are peeled off. Thereby, the wiring pattern layer 4a and the cover layer 5 are integrally formed on the metal substrate 1 via the insulating layer 2 (insulating layer etching step). Further, the metal substrate 1 is in a state in which the jig hole 1a and the flying hole 1b of the flying lead portion are formed. The processing of the insulating layer 2 may be performed by plasma etching.

  Next, as shown in FIG. 2G, the protective plating portion 6 is formed by performing Au plating or Ni—Au plating on the portion where the wiring pattern layer 4a is exposed (protective plating portion forming step).

  Next, in order to perform the external shape processing of the metal substrate 1, a metal etching resist is made on both surfaces of the laminate 10. In the present invention, “performing the outer shape of the metal substrate” means that the region of the metal substrate that has not been processed in the first metal etching step is processed according to the shape of the target suspension substrate. Specifically, a resist layer for metal etching is provided on both surfaces of the laminate 10, and resists 15 and 16 patterned as shown in FIG. 2H are formed by photolithography. In this case, a resist 15 is formed on the wiring side so as to cover the entire surface, and a resist 16 patterned in accordance with the target outer shape is formed on the substrate side.

  Then, as shown in FIG. 2I, the metal substrate 1 is etched using a chemical etching solution, and the resists 15 and 16 are peeled off. Thereby, a suspension substrate having a desired shape is obtained (second metal etching step). Thereafter, as shown in FIG. 2 (j), solder bump portions 7 are formed by printing on the terminal portions of the wiring pattern layer 4a as necessary. In the figure, A is a terminal part for forming a bump, B is a flying lead part, C is a wiring part, and may have a metal substrate 1 as required.

The manufacturing method of the suspension substrate of the present invention usually includes a laminate preparation step and a first metal etching step. Furthermore, it is preferable to have a cover layer forming step, an insulating layer etching step, a protective plating portion forming step, a second metal etching step, and a solder bump forming step, which will be described later.
Hereinafter, the manufacturing method of the suspension substrate according to the present invention will be described step by step.

1. Laminated body preparation process First, the laminated body preparation process in this invention is demonstrated. The laminate preparation step in the present invention is a step of preparing a laminate in which a metal substrate, an insulating layer, a seed layer, and a metal plating layer are arranged in this order.

  In the present invention, a suspension substrate having a low rigidity can be obtained by using a laminate having the above layer structure. Conventionally, a five-layer laminate has been used as a raw material for obtaining a suspension substrate. Specifically, as shown in FIG. 3A, SUS as the metal substrate 21, thermoplastic polyimide (TPI) as the adhesive layer 22, polyimide as the insulating layer 23, and TPI as the adhesive layer 24. And a five-layer laminate having Cu as the wiring pattern forming layer 25 has been used.

  However, this laminated body is usually formed by bonding and laminating rolled copper or the like, which is spring copper, with a press. Since rolled copper is used, it has not been possible to reduce the thickness and reduce the rigidity. Furthermore, since the above five-layer laminate is formed by pressing each constituent member, the pattern of the roughened surface of the wiring pattern forming layer (for example, rolled copper) is transferred to the insulating layer (for example, polyimide). . As a result, there has been a problem that the surface of the insulating layer is roughened, and the roughened surface is a factor that hinders fine wiring processing.

  On the other hand, in the laminate used in the present invention, as shown in FIG. 3B, for example, the metal substrate 1, the insulating layer 2, the seed layer 3, and the metal plating layer 4 are usually arranged in this order. It is a laminate of layers. Since the metal plating layer of this four-layered laminate is formed by an electrolytic plating method or the like, it can be made thinner and less rigid than conventional rolled copper or the like. A fine wiring pattern layer can also be formed. Furthermore, since the metal plating layer of the four-layer laminate is formed by an electrolytic plating method or the like, the surface of the insulating layer is roughened as in the case of the five-layer laminate described above. There is nothing. Therefore, there is an advantage that the problem of remaining foreign matter does not occur.

Next, the structural member of the laminated body used for this invention is demonstrated. The laminated body used for this invention has a metal substrate, an insulating layer, a seed layer, and a metal plating layer normally.
The material for the metal substrate is not particularly limited as long as it has electrical conductivity and appropriate springiness, and examples thereof include SUS. The film thickness of the metal substrate is, for example, preferably in the range of 10 μm to 30 μm, and more preferably in the range of 15 μm to 25 μm. If the metal substrate is too thin, the mechanical strength may be reduced, and if the metal substrate is too thick, it is difficult to reduce the rigidity of the suspension substrate.

  The material of the insulating layer is not particularly limited as long as it has insulating properties, and examples thereof include polyimide (PI). 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 20 μm, and particularly preferably in the range of 5 μm to 10 μm. This is because if the insulating layer is too thin, sufficient insulation may not be exhibited. If the insulating layer is too thick, it is difficult to reduce the rigidity of the suspension substrate.

  The material of the seed layer is not particularly limited as long as it can improve the adhesion between the insulating layer and the metal plating layer, and examples thereof include Ni, Cu, Cr, and alloys thereof. The seed layer is preferably a layer formed by a sputtering method. The film thickness of the seed layer is not particularly limited as long as desired adhesion can be obtained, but is usually in the range of 10 nm to 300 nm.

  The material for the metal plating layer is not particularly limited as long as it has good electrical conductivity, and examples thereof include copper (Cu). The film thickness of the metal plating layer is, for example, preferably in the range of 6 μm to 18 μm, and more preferably in the range of 8 μm to 12 μm. This is because if the metal plating layer is too thin, the mechanical strength may decrease, and if the metal plating layer is too thick, it is difficult to reduce the rigidity of the suspension substrate.

  The metal plating layer can be formed by a general plating method. In particular, in the present invention, the metal plating layer is preferably formed by an electrolytic plating method. This is because the metal plating layer can be formed with high accuracy. In the present invention, the difference between the maximum film thickness portion and the minimum film thickness portion of the metal plating layer is, for example, 2 μm or less, preferably 1.6 μm or less.

  In the present invention, the wiring pattern layer is formed by a method called a subtractive method in which the wiring pattern layer is formed by etching the metal plating layer. On the other hand, a method of forming a wiring pattern layer by an additive method is known. Specifically, a predetermined resist pattern is formed on the insulating layer, and the surface of the insulating layer on which the resist pattern is not formed is formed. In this method, a wiring pattern layer is formed by an electrolytic plating method or the like. By the way, when the wiring pattern layer is formed by the above-described additive method, there is a problem that the electric field becomes non-uniform due to the density of the resist pattern and the film thickness of the wiring pattern layer becomes large. On the other hand, when the wiring pattern layer is formed by the subtractive method as in the present invention, the film thickness of the wiring pattern layer is defined by the film thickness of the metal plating layer of the laminate that is the raw material. There is an advantage that the variation in film thickness is small.

  The method for forming the laminate used in the present invention is not particularly limited as long as it is a method capable of obtaining the above laminate. For example, a polyimide precursor is formed on the surface of SUS as a metal substrate. A method of forming an insulating layer made of polyimide by applying and heat-treating the containing coating solution, then forming a seed layer by a sputtering method, and finally forming a metal plating layer made of Cu plating by an electrolytic plating method Etc.

2. First Metal Etching Step Next, the first metal etching step in the present invention will be described. In the first metal etching step of the present invention, a patterned resist is formed on the surface of the metal substrate and the surface of the metal plating layer, and etching is performed to form a jig hole in the metal substrate. And it is the process of processing the said metal plating layer into a wiring pattern layer.

Further, this step is a step of forming a jig hole in the metal substrate and processing the metal plating layer into a wiring pattern layer. Therefore, the metal substrate and the metal plating layer may be etched simultaneously, but the metal substrate and the metal plating layer may be etched in order. Moreover, as an order of etching in the case of sequentially etching the metal substrate and the metal plating layer, either the metal substrate or the metal plating layer may be etched first.
In addition, when the said metal plating layer is etched, the said seed layer is normally etched simultaneously.

  Specifically, as shown in FIG. 1B and FIG. 1C described above, patterned resists 11 and 12 are formed on the surface of the metal substrate 1 and the surface of the metal plating layer 4 to form the metal substrate. 1 is a step of forming a jig hole 1a on the surface of 1 and processing the metal plating layer 4 into a wiring pattern layer 4a. In the present invention, if necessary, the hole 1b for forming the flying lead portion may be formed simultaneously with the jig hole 1a. In addition, when the double-sided connection as in the flying lead portion is not performed and the single-sided connection is sufficient, it is not necessary to form the hole 1b.

  In the present invention, jig holes and punch holes are formed in the metal substrate in the first metal etching step, but most of the metal substrate is not etched. Therefore, the insulating layer can be etched in a state where the rigidity of the laminated body is maintained high, and deformation of the laminated body during processing can be suppressed during conveyance between the processes. In the present invention, the processing of the metal substrate other than the jig hole is usually performed in a second metal etching step described later.

  In the present invention, jig holes are formed in the metal substrate when the metal plating layer is processed into the wiring pattern layer. Thereby, first, the relative positional relationship between the jig hole and the wiring pattern layer can be determined. In the present invention, the “jig hole” refers to a hole for fixing the laminated body with a jig, and various alignments are performed based on the jig hole. In the present invention, the laminated body can be processed with high accuracy by unifying the alignment reference to the jig hole. The shape of the jig hole varies depending on the shape of the jig used, but is usually a circle or a long hole. Although the diameter of a jig hole is not specifically limited, For example, it exists in the range of 0.5 mm-3 mm.

In the first metal etching step, at least a jig hole is formed in the metal substrate, and if necessary, a hole for the flying lead is simultaneously formed. On the other hand, if the metal substrate of the laminated body after completion of the first metal etching step maintains a certain degree of rigidity, it is possible to prevent the laminated body being processed from being deformed during conveyance. The surface of the metal substrate, the area of the region to be processed by the first metal etching step was S _A, when the total area was S _T, the S A _/ S _T, for example 0.6 or less, preferably 0. It is preferable to be within the range of 01 to 0.5.

  On the other hand, on the wiring side, a wiring pattern layer is formed by etching the metal plating layer. Since the metal plating layer used in the present invention is usually thinner than conventional rolled copper or the like, a fine wiring pattern layer can be formed. The width of the wiring pattern is, for example, preferably 10 μm or more, and more preferably in the range of 20 μm to 30 μm. On the other hand, the interval between adjacent wiring patterns is, for example, preferably 10 μm or more, and more preferably in the range of 20 μm to 30 μm.

  The resist used in the present invention may be a solid resist or a liquid resist. However, since the number of steps is increased, a solid resist is preferable. Specifically, it is preferable to use a dry film resist (DFR). This is because a fine wiring pattern layer can be obtained.

  The method for forming the patterned resist on the surface of the metal substrate and the surface of the metal plating layer is not particularly limited, and a general method can be used. Specifically, a method may be mentioned in which a resist is arranged on the surface of the metal substrate and the surface of the metal plating layer, developed in a desired pattern, and then developed.

  Examples of the method for etching the metal substrate and the metal plating layer include wet etching. Furthermore, it is preferable that the etching solution used for wet etching is appropriately selected according to the material of the metal substrate and the metal plating layer to be used. For example, when the metal substrate is SUS, a ferric chloride etching solution can be used. When the metal plating layer is a copper plating layer, a ferric chloride etching solution or a copper chloride etching solution can be used. In the present invention, after the patterned resist is formed, the metal substrate and the metal plating layer may be etched separately, but it is preferable to simultaneously etch the metal substrate and the metal plating layer. This is because the number of processes is reduced.

3. Cover Layer Formation Step Next, the cover layer formation step in the present invention will be described. The cover layer forming step in the present invention is a step of forming a cover layer having a wiring pattern layer exposed opening through which a part of the surface of the wiring pattern layer is exposed using a liquid cover material.

  Specifically, as shown in FIG. 1D described above, in the step of forming the cover layer 5 having a wiring pattern layer exposed opening (not shown) in which a part of the surface of the wiring pattern layer 4a is exposed. is there. A protective plating portion to be described later is formed on the surface of the wiring pattern layer 4a exposed through the wiring pattern layer exposure opening.

  In the present invention, by forming the cover layer before etching the insulating layer, the liquid cover material can be prevented from flowing into the jig hole or the like. Thereby, a cover layer having a uniform film thickness can be formed. FIG. 4 is an explanatory view for explaining a conventional cover layer forming step. For the sake of convenience, the description of the seed layer is omitted, and description of some reference numerals overlapping with those in FIG. 1 is also omitted. Conventionally, as shown in FIG. 4A, since the insulating layer 2 has already been etched before the cover layer is formed, the jig hole 1b has penetrated. Therefore, when forming a cover layer using a liquid cover material, it is necessary to arrange the outflow prevention material 31 under the jig hole 1b (FIG. 4B), and the outflow prevention material 31 is arranged. Even in this case, the liquid cover material 5 ′ may flow into the jig hole 1 b (FIG. 4C). As a result, the film thickness of the obtained cover layer 5 becomes non-uniform, and there is a problem that a region of the wiring pattern layer 4a that is not covered by the cover layer 5 is generated (FIG. 4D). In addition, for this reason, in the suspension substrate formed by the conventional method, the film thickness of the cover layer formed at a location where many jig holes or punch holes are formed, the jig hole or There has been a problem that the difference from the film thickness of the cover layer formed in a portion having few punch holes becomes large.

  On the other hand, in the present invention, the liquid cover material can be prevented from flowing in by forming the cover layer before the insulating layer is etched. Here, FIG. 5 is an explanatory view for explaining the cover layer forming step in the present invention. For the sake of convenience, the description of the seed layer is omitted, and description of some reference numerals overlapping with those in FIG. 1 is also omitted. In the present invention, as shown in FIG. 5A, the cover layer is formed at a stage before the insulating layer 2 is etched. Unlike the conventional method, the jig hole 1b is not penetrating. Therefore, the liquid cover material 5 ′ does not flow into the jig hole 1 b (FIG. 5B), the cover layer 5 having a uniform film thickness can be obtained, and the wiring pattern layer not covered by the cover layer 5 It is possible to prevent the occurrence of the region 4a (FIG. 5C). Then, after forming the cover layer 5, the insulating layer 2 is etched (FIG. 5D).

For this reason, in the suspension substrate manufactured by performing this step, the film thickness of the cover layer formed at a location where many jig holes or punch holes are formed, and the jig holes or punch holes are not formed. A difference with the film thickness of the cover layer formed in few places becomes small. Therefore, the film thickness of the cover layer on the wiring pattern layer in the suspension substrate can be made uniform.
Here, when the difference in the film thickness of the cover layer is large, there is a possibility that a portion where the wiring pattern layer is not sufficiently covered occurs due to the thin film thickness of the cover layer. Therefore, in order to prevent such an uncovered portion from occurring, it is necessary to increase the thickness of the cover layer as a whole.
On the other hand, since the cover layer formed in this step can have a uniform film thickness on the wiring pattern layer, the covering of the wiring pattern layer by the cover layer can be ensured. . Moreover, the film thickness of the said cover layer can be made thin from such a thing.
Furthermore, since the film thickness of the cover layer can be made thin, the suspension substrate manufactured by the manufacturing method of the present invention can be reduced in rigidity and weight. As a result, when the suspension board is used in a hard disk drive, the power consumption can be reduced.
The difference between the maximum film thickness portion and the minimum film thickness portion of the cover layer on the wiring pattern layer is, for example, 1.3 μm or less, preferably 1.0 μm or less.

  The liquid cover material used in the present invention contains at least a cover layer forming resin. Furthermore, you may contain the solvent which dissolves the resin for cover layer formation as needed. Examples of the cover layer forming resin include a polyimide resin and an epoxy resin. The resin for forming the cover layer may be a photosensitive resin or a non-photosensitive resin, but among them, the non-photosensitive resin is preferable. This is because a thin cover layer can be formed.

The liquid cover material preferably has a low viscosity. This is because a thin cover layer can be obtained. The viscosity of the liquid cover material is, for example, preferably in the range of 500 cP to 5000 cP at room temperature, and more preferably in the range of 500 cP to 1000 cP.
The thickness of the cover layer formed on the wiring pattern layer is not particularly limited, but is preferably in the range of 3 μm to 20 μm, and more preferably in the range of 5 μm to 10 μm.
The viscosity of the liquid cover material is usually in the range of 500 cP to 10,000 cP when the cover layer using the liquid cover material is formed by hoop processing. Moreover, when performed by the screen printing method, it is usually in the range of 10,000 cP to 40,000 cP.

  The method for forming the cover layer is not particularly limited as long as it uses a liquid cover material. For example, when the liquid cover material contains a photosensitive resin, a method of applying the liquid cover material so as to cover the wiring pattern layer, drying, exposing and developing, and the like can be exemplified. On the other hand, when the liquid cover material contains a non-photosensitive resin, the following method can be employed. That is, first, a liquid cover material is applied so as to cover the wiring pattern layer, and dried to form a non-photosensitive resin layer. Next, a photosensitive resin layer is formed on the non-photosensitive resin layer, and the photosensitive resin layer is exposed in a pattern. Next, simultaneously with the development of the exposed photosensitive resin layer, the non-photosensitive resin layer is etched, and finally the photosensitive resin layer is peeled off. By this method, a thin cover layer can be obtained.

4). Insulating Layer Etching Step Next, the insulating layer etching step in the present invention will be described. The insulating layer etching step in the present invention is a step of etching the insulating layer after forming the cover layer.

  Specifically, as shown in FIG. 1E and FIG. 1F described above, patterned resists 13 and 14 for polyimide etching are formed on both surfaces of the laminate 10, and an etching solution is used. This is a step of etching the insulating layer 2. The jig hole 1a penetrates for the first time by this process. Moreover, you may form the hole 1b of a flying lead part simultaneously as needed.

  In the present invention, either the insulating layer etching step or the protective plating portion forming step to be described later may be performed first. For example, a suspension substrate having a flying lead portion that can be connected on both sides is used. When forming, usually, an insulating layer etching step is first performed, and then a protective plating portion forming step is performed. This is because it is necessary to form a hole in the flying lead portion. On the other hand, when the double-sided connection as in the flying lead portion is not performed and the single-sided connection is sufficient, either of the insulating layer etching step and the protective plating portion forming step may be performed first.

  In the present invention, the etching pattern of the insulating layer is preferably set as appropriate according to the shape of the target suspension substrate. As a method for etching the insulating layer, as described above, a method of forming a patterned resist in a region not to be etched, and then etching the insulating layer with a predetermined etching solution can be used. In the present invention, it is preferable to use a dry film resist. In addition, the insulating layer may be etched by plasma etching or the like.

5. Next, the protective plating part forming step in the present invention will be described. The protective plating portion forming step in the present invention is a step of forming a protective plating portion on the surface of the wiring pattern layer exposed through the wiring pattern layer exposure opening.

  Specifically, as shown in FIG. 2G described above, a step of forming the protective plating portion 6 on the surface of the wiring pattern layer 4a exposed from the wiring pattern layer exposed opening formed by the cover layer forming step. It is.

  In the present invention, first, a cover layer is formed, and a protective plating portion is formed only on the surface of the wiring pattern layer exposed from the wiring pattern layer exposed opening of the cover layer, thereby obtaining a low-rigidity suspension substrate. Can do. Conventionally, the protective plating portion is formed before the cover layer is formed. For example, as shown in FIG. 6A, the protective plating portion 6 is formed on the surface and side surfaces of the wiring pattern layer 4a. For this reason, there has been a problem that the suspension substrate cannot be sufficiently reduced in rigidity.

  On the other hand, in the present invention, by forming the cover layer before forming the protective plating portion, for example, as shown in FIG. 6 (b), only a necessary portion of the surface of the wiring pattern layer 4a is protected. The plating part 6 can be formed, and the rigidity of the suspension substrate can be sufficiently reduced. In FIG. 6, the description of a part of the reference numerals overlapping those in FIG. 1 is omitted.

  The material of the protective plating portion used in the present invention is not particularly limited as long as it can prevent corrosion of the wiring pattern layer and the like. For example, nickel (Ni), gold (Au), etc. Among them, gold (Au) is preferable. It is because it is excellent in corrosion resistance.

The film thickness of the protective plating portion is, for example, 5 μm or less, and preferably in the range of 1 μm to 2 μm. It is because corrosion of a wiring pattern layer etc. can be prevented effectively because it is the said range.
The protective plating portion can be formed by a general plating method. Especially in this invention, it is preferable that the said protective plating part is formed by the electroplating method. This is because the protective plating portion can be formed with high accuracy.

6). Second Metal Etching Step Next, the second metal etching step in the present invention will be described. The 2nd metal etching process in this invention is a process of performing the external shape process of the said metal substrate after the said insulating layer etching process and the said protective plating part formation process.

  Specifically, as shown in FIG. 2 (h) and FIG. 2 (i) described above, patterned resists 15 and 16 for metal etching are formed on both surfaces of the laminate 10, and metal is etched using an etching solution. This is a step of performing the outer shape processing of the substrate 1.

  In the present invention, jig holes and punch holes are formed in the metal substrate in the first metal etching step, but most of the metal substrate is not etched. Therefore, the insulating layer can be etched in a state where the rigidity of the laminated body is maintained high, and deformation of the laminated body during processing can be suppressed during conveyance. Thereafter, after the etching of the insulating layer or the like is finished, the unprocessed metal substrate is etched according to a predetermined shape, whereby a low-rigidity suspension substrate can be manufactured with a high yield.

  The method for etching the metal substrate and the kind of the etching solution used are the same as the contents described in the above “1. First metal etching step”, and thus the description thereof is omitted here.

7). Solder bump part formation process In this invention, you may perform the solder bump part formation process which forms a solder bump part on the protective plating part of a terminal part after a 2nd metal etching process. The solder bump portion forming step is a step of forming the solder bump portion 7 on the surface of the protective plating portion 6 of the terminal portion A as shown in FIG.

  The solder used to form the solder bump portion can be roughly classified into lead-containing solder and lead-free solder. Among these, in the present invention, it is preferable to use lead-free solder. This is because the load on the environment can be reduced. Specific examples of the lead-free solder include Sn—Sb, Sn—Cu, Sn—Cu—Ni, Sn—Ag, Sn—Ag—Cu, Sn—Ag—Cu—Bi, Examples thereof include Sn—Zn, Sn—Ag—In—Bi, Sn—Zn, Sn—Bi, Sn—In, and Sn—Sb solders.

  The method for forming the solder bump portion is not particularly limited as long as it is a method capable of forming a desired solder bump portion, and examples thereof include a screen printing method, a dispensing method, an ink jet method, and the like. Screen printing is preferred.

8). Others As described in the above “3. Cover layer forming step”, in the present invention, the liquid cover material is prevented from flowing into the jig hole by forming the cover layer before etching the insulating layer. can do. From this point of view, in the present invention, the suspension has a laminate preparation step, a first metal etching step, a cover layer forming step, an insulating layer etching step, and a second metal etching step. The manufacturing method of the board | substrate can be provided. Since each process is the same as the content mentioned above, description here is abbreviate | omitted.

  Further, as described in the above “5. Protection plating portion forming step”, in the present invention, a cover layer is first formed, and only on the surface of the wiring pattern layer exposed from the wiring pattern layer exposed opening of the cover layer. By forming the protective plating portion, a suspension substrate with low rigidity can be obtained. From this point of view, the present invention is characterized by having a laminate preparation step, a first metal etching step, a cover layer forming step, a protective plating portion forming step, and a second metal etching step. A method of manufacturing a suspension substrate can be provided. Since each process is the same as the above-mentioned content, description here is abbreviate | omitted.

  In this invention, it may replace with the said cover layer formation process and may perform the dry cover layer formation process which forms a cover layer using the dry film for cover layer formation. By forming a cover layer before etching the insulating layer, when the cover layer forming dry film is laminated on the wiring pattern layer, the cover layer forming dry film flows into a jig hole or the like. It is because it can prevent. This is because a cover layer having a uniform film thickness can be formed. Further, the film thickness of the cover layer in the suspension substrate can be made uniform.

In the dry cover layer forming step, the method for forming the cover layer may be a method using a dry film for forming a cover layer. Specifically, after the cover layer forming dry film is disposed so as to cover the surface of the wiring pattern layer, it is laminated by thermocompression bonding. Then, the method of exposing and developing the laminated dry film for cover layer formation can be mentioned.
Here, the exposure and development methods can be the same as those described in the above section “3. Cover layer forming step”. Moreover, as the dry film for forming the cover layer, those generally used for manufacturing a suspension substrate can be used.

B. Next, the suspension substrate of the present invention will be described. The suspension of the present invention includes a metal substrate, an insulating layer formed on the metal substrate, a seed layer formed on the insulating layer, and a metal plating layer formed in a pattern on the seed layer. At least a wiring pattern layer, and the difference between the maximum film thickness portion and the minimum film thickness portion of the wiring pattern layer is 2 μm or less.

Such a suspension substrate may be as shown in FIG. 2 (j) already described.
Here, the difference between the maximum film thickness portion and the minimum film thickness portion of the wiring pattern layer 4a is 2 μm or less.

  According to the present invention, since the difference between the maximum film thickness portion and the minimum film thickness portion of the wiring pattern layer is 2 μm or less, the wiring pattern layer can be easily thinned and lightweight. Can do.

The suspension substrate of the present invention has at least a metal substrate, an insulating layer, a seed layer, and a wiring pattern layer. Moreover, you may have a cover layer as needed.
The metal substrate, the insulating layer, and the seed layer can be the same as those described in the above section “A. Method for manufacturing suspension substrate”, and thus the description thereof is omitted here.

1. Wiring pattern layer The wiring pattern layer used in the present invention is composed of a metal plating layer formed in a pattern on the seed layer. Further, the difference between the maximum film thickness portion and the minimum film thickness portion of the wiring pattern layer is 2 μm or less.

Examples of such a wiring pattern layer include those formed by forming a metal plating layer on the entire surface of the seed layer, forming a patterned resist, and etching.
In the present invention, the difference between the maximum film thickness portion and the minimum film thickness portion of the metal plating layer formed on the entire surface of the seed layer is preferably 2 μm or less. This is because the difference between the maximum film thickness portion and the minimum film thickness portion of the wiring pattern layer is surely 2 μm or less.

  The metal plating, the method for etching the metal plating, and the wiring pattern layer may be specifically the same as the contents described in the above section “A. Method for manufacturing suspension substrate”. it can.

2. Cover Layer The cover layer used in the present invention is formed on the wiring pattern layer using the cover material and has a wiring pattern layer exposure opening that exposes a part of the surface of the wiring pattern layer. good.

  As a cover material used for forming such a cover layer, a liquid cover material, a dry film for forming a cover layer, and the like can be used. In the present invention, it is particularly preferable to use a liquid cover material. This is because the cover layer can be made thin. As a result, it is possible to reduce the rigidity and weight. Furthermore, this makes it possible to reduce the power consumption when the suspension substrate of the present invention is used in a hard disk drive.

  The difference between the maximum film thickness portion and the minimum film thickness portion on the wiring pattern layer of the cover material and the cover layer, etc., is the same as the contents described in the section “A. Method for manufacturing suspension substrate”. Since it can be the same, description here is abbreviate | omitted.

3. Suspension Substrate The suspension substrate of the present invention has at least a metal substrate, an insulating layer, a seed layer, and a wiring pattern layer. Moreover, it has a cover layer as needed. Furthermore, you may have a protective plating part, a solder bump part, etc. as needed.
The protective plating portion and the solder bump portion can be the same as those described in the above section “A. Method for manufacturing suspension substrate”.

  As a manufacturing method of the suspension substrate of the present invention, at least the metal substrate, the insulating layer, the seed layer, and the wiring pattern layer are accurately laminated according to the use of the suspension substrate of the present invention. Specifically, the method described in the above-mentioned “A. Manufacturing method of suspension substrate” can be used.

  Examples of the use of the suspension substrate of the present invention include suspensions used in hard disk drives. Among them, the suspension substrate is suitably used for suspensions that are required to have low rigidity and light weight.

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

Such a suspension of the present invention will be described with reference to the drawings. FIG. 7 is a schematic view showing an example of the suspension of the present invention. As illustrated in FIG. 7, the suspension 40 of the present invention includes the suspension substrate 20 and a load beam 41, and the load beam 41 is provided with a magnetic head slider in the suspension substrate 20. It is adhered to the surface on the side where the slider installation position 30 is not formed.
Here, the suspension substrate is the suspension substrate described in the section “B. Suspension substrate”.

  According to the present invention, since the suspension substrate is included, the rigidity and weight can be reduced.

The suspension of the present invention has at least the suspension substrate.
Such a suspension substrate is the same as the content described in the section “B. Suspension substrate”, and thus the description thereof is omitted here.

  The suspension of the present invention has at least the suspension substrate, but usually has a load beam. As such a load beam, any material can be used as long as it can give a desired rigidity to the suspension when the suspension of the present invention is used in the hard disk drive. Can be used.

  Examples of the use of the suspension of the present invention include a suspension with a head of a hard disk drive. Among them, the suspension with a head that is required to have low rigidity and light weight is preferably used.

D. Next, the suspension with a head according to the present invention will be described. A suspension with a head according to the present invention includes the suspension and a magnetic head slider mounted on the suspension.

Such a suspension with a head according to the present invention will be described with reference to the drawings. FIG. 8 is a schematic view showing an example of a suspension with a head according to the present invention. As illustrated in FIG. 8, the suspension 50 with a head according to the present invention includes the suspension 40 and a magnetic head slider 51 mounted on a slider installation position on the suspension 40.
Here, the suspension is the suspension described in the section “C. Suspension”.
Note that the reference numerals in FIG. 8 are the same as those in FIG.

  According to the present invention, since the suspension is included, it is possible to achieve low rigidity and light weight.

The suspension with a head of the present invention has at least the suspension and the magnetic head slider.
The suspension is the same as the content described in the section “C. Suspension”, and thus the description thereof is omitted here.

  The magnetic head slider used in the present invention is not limited as long as it can write and read data on the disk when the suspension with a head of the present invention is used in a hard disk drive. What is used can be used.

  As an application of the suspension with a head of the present invention, a hard disk drive can be cited, and among these, it is preferably used for a hard disk drive that is required to be low rigidity and light weight.

E. Next, the hard disk drive of the present invention will be described. The hard disk drive of the present invention includes the above suspension with a head.

Such a hard disk drive of the present invention will be described with reference to the drawings. FIG. 9 is a schematic plan view showing an example of the internal structure of the hard disk drive of the present invention. As illustrated in FIG. 9, the hard disk drive 60 of the present invention includes a suspension 50 with a head, a disk 61 on which data is written to and read from the suspension 50 with a head, and a spindle motor 62 that rotates the disk 61. An arm 63 connected to the suspension 50 with head, a voice coil motor 64 that moves the slider of the suspension 50 with head to a desired position on the disk 61 by moving the arm 63, and And a case 65 for sealing each component.
Here, the suspension with a head is the suspension described in the section “D. Suspension with a head”.

  According to the present invention, since the suspension with a head is included, the power consumption can be reduced.

The hard disk drive of the present invention has at least the above suspension with a head.
Such a suspension with a head is the same as the content described in the above section “D. Suspension with a head”, and thus the description thereof is omitted here.

  The hard disk drive of the present invention has at least the above suspension with a head, but usually has a disk, a spindle motor, an arm, and a voice coil motor. As such a disk, a spindle motor, an arm, and a voice coil motor, those generally used for hard disk drives 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]
A 10 μm-thick polyimide (insulating layer) is formed on a 20 μm-thick SUS304 (metal substrate) by a coating method, and Ni—Cr—Cu serving as a seed layer is further formed on the insulating layer by a sputtering method. Coating was performed with 300 nm, and this was used as a conductive layer to form a 9 μm thick Cu plating layer (metal plating layer) by Cu plating to obtain a four-layer laminate (see FIG. 1A). Using this four-layer laminate, a suspension substrate having low rigidity and fine wiring was produced.

  First, a patterned resist was obtained by patterning simultaneously using a dry film so that a jig hole whose positional accuracy was important on the SUS side and a desired wiring pattern layer on the Cu plating layer side could be formed. Then, it etched using the ferric chloride liquid, and resist stripping was performed after the etching (refer 1st metal etching process, FIG.1 (b), (c)). Here, by positioning the dry film at the same time, it is possible to improve the positional accuracy of both surfaces on the SUS side and the wiring pattern layer side. In addition, the width | variety of the copper wiring formed in the wiring pattern layer was 20 micrometers, and the space | interval of copper wiring was 20 micrometers. It is considered that the miniaturization of the wiring greatly contributes to the fact that there is no anchor shape in the wiring pattern layer and that a highly sensitive DFR resist is used.

  Next, a non-photosensitive polyimide liquid cover material was coated with a die coater, dried, resist-engraved, the liquid cover material was etched simultaneously with development, and then cured to obtain a cover layer (FIG. 1 (d )reference). The film thickness of the cover layer after curing was 5 μm on the wiring. By forming such a cover layer, it is possible to control warpage and reduce rigidity, and to protect the wiring pattern layer.

  Next, polyimide (insulating layer) having a thickness of 10 μm was engraved with a resist and etched using an organic alkaline etching solution to obtain a patterned insulating layer (see FIGS. 1E and 1F). Then, 2 μm thick Au plating was performed on the exposed wiring pattern layer to form a protective plating portion (see FIG. 2G). In the present invention, the wiring cover is first implemented, and Au plating can be performed only on the portion not covered with the cover layer, and a great effect can be obtained in reducing the rigidity and reducing the amount of Au.

  Next, in order to perform the outer shape processing of SUS, resist plate making was performed by the same method as the first metal etching step described above, and only the SUS side was etched (second metal etching step, FIG. 2 (h)). (See (i)). Finally, after the second metal etching step, solder bumps were formed by screen printing using a lead-free solder paste (FIG. 2 (j)). The suspension substrate thus obtained had a lower rigidity and finer wiring than conventional products.

[Example 2]
A suspension substrate was prepared in the same manner as in Example 1 except that a non-photosensitive polyimide liquid cover material was coated with a die coater.

[Example 3]
A suspension substrate was prepared in the same manner as in Example 2 except that the amount of the non-photosensitive polyimide liquid cover material to be coated was changed.

[Comparative Example 1]
A suspension substrate was produced in the same manner as in Example 2 except that the cover layer was formed after obtaining the patterned insulating layer.

[Comparative Example 2]
A suspension substrate was prepared in the same manner as in Comparative Example 1 except that the amount of the non-photosensitive polyimide liquid cover material to be coated was changed.

[Evaluation]
About the suspension substrates produced in Examples 2-3 and Comparative Examples 1-2, as shown by X in FIG. 10, the insulating layer etched around, that is, the cover layer in the place where the through hole is formed The thickness was measured. The results are shown in Table 1 below.
Further, as indicated by Y in FIG. 10, the thickness of the cover layer at a location where the insulating layer etched around was not formed was measured. The results are shown in Table 2 below.
The measurement was performed by preparing eight suspension substrates and measuring the film thickness at X and Y for each.
Furthermore, as the film thickness difference of the cover layer in the suspension substrate, the average (XY film thickness difference) of the film thickness differences in the regions indicated by X and Y in FIG. 10 in each sample was calculated. The results are shown in Table 3 below.

  According to Table 3, in the example in which the patterned insulating layer was formed after the cover layer was formed, the average difference in film thickness (X − in the region indicated by X and the region indicated by Y in FIG. 10). Y film thickness difference) could be 1 μm or less. On the other hand, in the comparative example in which the cover layer was formed after obtaining the patterned insulating layer, the XY film thickness difference was 2 μm or more.

It is explanatory drawing explaining an example of the manufacturing method of the board | substrate for suspensions of this invention. It is explanatory drawing explaining an example of the manufacturing method of the board | substrate for suspensions of this invention. It is a schematic sectional drawing explaining the laminated constitution of a laminated body. It is explanatory drawing explaining the conventional cover layer formation process. It is explanatory drawing explaining the cover layer formation process in this invention. It is explanatory drawing explaining a protective plating part. It is the schematic which shows an example of the suspension of this invention. It is the schematic which shows an example of the suspension with a head of this invention. It is the schematic which shows an example of the internal structure of the hard-disk drive of this invention. It is explanatory drawing explaining the board | substrate for suspension produced in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Metal substrate 1a ... Jig hole 1b ... Extraction hole 2 ... Insulating layer 3 ... Seed layer 4 ... Metal plating layer 4a ... Wiring pattern layer 5 ... Cover layer 6 ... Protection plating part 7 ... Solder part 10 ... Laminate 20 ... Suspension substrate 30 ... Slider installation position 40 ... Suspension 50 ... Suspension with head 51 ... Magnetic head slider 60 ... Hard disk drive

Claims (3)

A laminate preparation step of preparing a laminate in which a metal substrate, an insulating layer, a seed layer, and a metal plating layer are arranged in this order;
A patterned resist is formed on the surface of the metal substrate and the surface of the metal plating layer, and etching is performed to form jig holes in the metal substrate, and the metal plating layer is used as a wiring pattern layer. A first metal etching step to be processed;
A cover layer forming step of forming a cover layer having a wiring pattern layer exposed opening in which a part of the surface of the wiring pattern layer is exposed by arranging a cover material and etching the cover material;
An insulating layer etching step of etching the insulating layer after forming a cover layer having the wiring pattern layer exposed opening;
I have a,
The cover material is a polyimide liquid cover material,
The insulating layer is made of polyimide,
The method for manufacturing a suspension substrate, wherein the insulating layer etching step etches the insulating layer so that the shape of the opening between the cover layer and the insulating layer is different . The method for manufacturing a suspension substrate according to claim 1, wherein a difference between the maximum film thickness portion and the minimum film thickness portion of the metal plating layer is 2 μm or less. The method for manufacturing a suspension substrate according to claim 1 or 2 , wherein a difference between the maximum film thickness portion and the minimum film thickness portion on the wiring pattern layer of the cover layer is 1 µm or less.

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