JP5246521B2 - Manufacturing method of electronic parts adopting wet etching, electronic parts and hard disk suspension - Google Patents

Description

  In the present invention, an insulating layer is wet by using a single-wafer laminate having a layer structure of conductive inorganic material-insulating layer-conductive inorganic material, or conductive inorganic material-insulating layer, which can be patterned by a wet process. The present invention relates to a method of manufacturing an electronic component by a patterning process by etching, an electronic component itself obtained by the manufacturing method, and a suspension for a hard disk drive.

  In recent years, with the rapid development of semiconductor technology, miniaturization of semiconductor packages, increase in pin count, fine pitch, miniaturization of electronic components, etc. have rapidly progressed, and the era of so-called high-density packaging has been entered. Along with this, printed wiring boards have been made thinner and thinner from single-sided wiring to double-sided wiring (Iwata, Harazoen, Electronic Materials, 35 (10), 53 (1996)).

  A pattern forming method for forming such wiring / circuits for electronic components includes a conductive inorganic material layer (mainly metal layer) -insulating layer-conductive inorganic material layer (mainly metal layer) in a conductive layer structure. After the conductive inorganic layer is etched with an acidic solution such as ferric chloride and wiring is formed, an insulating layer is formed in a dry state such as plasma etching or a wet state such as hydrazine in order to establish electrical connection between the layers. There is a method of connecting the wirings by plating or conductive paste or the like by removing them into a shape (Japanese Patent Laid-Open No. 6-164084). Another pattern forming method is a method in which an insulating layer is provided in a desired shape using photosensitive polyimide (Japanese Patent Laid-Open No. 4-168441) or the like, and then wiring is formed in the gap by plating (electronic packaging) Proceedings of the 7th Research Discussion Meeting of the Society (published in 1999).

  In recent years, the price of electric products, especially personal computers, has been reduced, and the components and parts used for these products are strongly priced, so how to make electronic components at a low cost is a very big issue. It has become.

  Currently, along with the rapid growth of personal computer production, the production of hard disk drives built into it is also increasing. In a hard disk drive, a part called a suspension that supports a magnetic reading head connects a copper wire to a stainless steel leaf spring, and a copper wire is directly formed on the stainless steel leaf spring to cope with downsizing. The main product is changing to what is called wireless suspension.

  Such a wireless suspension is mainly manufactured using a three-layer material composed of a conductive inorganic layer (mainly metal layer) -insulating layer-conductive inorganic layer (mainly metal layer). Examples of the three-layer material include a layer structure in which a copper alloy foil is laminated on one side of an insulating layer and a stainless steel foil is laminated on the other side. The wireless suspension is a member that scans on a disk that rotates at high speed and applies fine vibrations. Therefore, the adhesion strength of the wiring (conductive inorganic layer) to the insulating layer is very important, and strict specifications are required. ing. In addition, since the hard disk is a device for recording information, high reliability is required for reading and writing data, and the specifications are strict against the adhesion strength of wiring, dust such as dust generated from the suspension, and outgas.

  In general, the laminate such as the above three-layer material used for electronic components is a low-expansion insulating layer in order to make the thermal expansion coefficient of the conductive inorganic layer and the insulating layer the same in order to prevent warping of the substrate, In particular, low expansion polyimide is often included. Laminates using only low-expansion polyimide for the insulating layer are low-expansion polyimide Kapton (trade name) manufactured by Toray DuPont Co., Ltd., Upilex (trade name) manufactured by Ube Industries, Ltd. Polyimide films such as Apical (trade name) manufactured by Co., Ltd. are used, and these form a metal layer (mainly copper) by sputtering or electroless plating on the surface of the low expansion polyimide film, and then electrolysis There is one in which the thickness of the conductor layer is increased by plating (referred to as a type I laminate). In addition, as another type of laminate, an adhesive other than polyimide (for example, an epoxy adhesive) is formed on the surface of low expansion polyimide, other than polyimide-low expansion polyimide-other than polyimide There is a laminate in which a conductor foil is bonded to the insulating layer by thermocompression bonding using an insulator having a three-layer structure made of the above adhesive (referred to as a type II laminate). Furthermore, as another type of laminate, an insulator having a three-layer structure composed of adhesive polyimide-low-expansion polyimide-adhesive polyimide formed by forming an adhesive polyimide layer on the surface of low-expansion polyimide, There is a laminate in which a conductor foil is bonded to the insulating layer by thermocompression bonding (referred to as a type III laminate).

  In the type I laminate, since the insulating layer is made of a single composition polyimide, it is difficult to warp, and the metal layer can be made thin, which is advantageous for forming a thin wiring. There is an advantage of being. Since the type II laminate and the type III laminate are formed by thermocompression bonding, various conductor layers can be selected. For example, it is possible to produce a laminated body using rolled copper foil, stainless steel foil, or the like. Type II laminates have good adhesion, and Type III laminates have the advantage of good heat resistance because the adhesive layer is polyimide with good heat resistance. Moreover, both have the advantage that the thickness of a metal layer can be enlarged.

  Since the wireless suspension requires springiness, a stainless steel foil is often used as the metal layer, and examples of the laminated structure include copper foil-adhesive polyimide-low expansion polyimide-adhesive polyimide-stainless. It is done. Conventionally, since a wireless suspension has a large etching area of an insulating layer, the insulating layer is mainly patterned by plasma etching, which is the same dry process, instead of a laser. However, since plasma etching has a low etching rate, the time required for etching is long, and since it is produced in units of sheets (sheets), the productivity is poor and the apparatus is expensive, so the production cost is very high. There is a fault that becomes.

  For these reasons, it has been desired to pattern the insulating layer by a wet process that has a high etching rate, and thus can be produced with high productivity and low device cost.

  Furthermore, wet etching technology is also used for electronic parts such as flexible printed boards and multilayer boards that have been drilled with a laser in a hole for conducting conduction between the layers of the multilayer board and then punched with a mold. As a result, the drilling and die-cutting processes can be performed at the same time, and even fine shapes that could not be cut out with the mold can be formed. It is desired.

  With regard to the type II laminate, when an epoxy adhesive is used, there is a disadvantage that the solvent resistance is too high to perform wet etching at all.

  For the type III laminate, the difference in etching characteristics between the adhesive polyimide layer and the low-expansion polyimide layer is too great, so that the cross-sectional shape when etched is not clean, and an electronic component is actually produced by wet etching. Is difficult.

  The type I laminate is partially processed by wet etching. However, since the formation of the conductive inorganic layer is a process such as sputtering, metal is struck against the polyimide surface at high speed, so the metal penetrates not only into the surface layer but also inside the polyimide layer, so the surface polyimide is slightly modified Resulting in. In the type I laminate, the adhesion between the insulating layer and the conductive inorganic layer is mainly due to the chemical bond or chemical interaction between the conductive inorganic layer and the insulating layer. The affinity with is getting stronger. Therefore, when wet etching is performed on the type I laminate, there is a problem that a defect in which the modified portion is left as an etching residue in the insulating layer at the interface with the conductive inorganic layer is likely to occur.

  On the other hand, in the laminated body in which the conductive inorganic layer and the insulating layer are integrated by pressing, the anchor effect due to the irregularities on the surface of the conductive inorganic layer contributes more to the adhesion than chemical bonds and chemical interactions. Therefore, it is difficult for etching residue to occur. In addition, as described above, in the production of a laminate by pressing, there is a great degree of freedom in selecting a conductive inorganic layer, so products that have been formed with a conductive inorganic layer by sputtering so far have not been applicable. Can be produced.

  In general, polyimide is often poor in solvent solubility, but since it is decomposed by a solution of hydrazine or alkali, various wet etching of a polyimide film with a chemical solution has been studied so far. For example, Japanese Patent Application Laid-Open No. 50-4577 discloses a method for manufacturing a wiring structure using hydrazine and ammonia. Japanese Laid-Open Patent Publication No. 58-103531 discloses a method for etching a polyimide film with an inorganic basic aqueous solution. Japanese Laid-Open Patent Publication No. 57-65727 discloses a polyimide etching method using an aliphatic diamine. In addition, the currently disclosed polyimide wet etching method uses a chemical solution in which water or an organic polar solvent is mixed with hydrazine, inorganic alkali, organic alkali, aliphatic amine (diamine), or aliphatic alcohol as a solvent. (For example, JP-A-58-74041, JP-A-58-96632, JP-A-3-101228, JP-A-5-190610, JP-A-5-202206) Gazette, JP-A-7-157560).

  However, since hydrazine, which is a component that decomposes polyimide, is highly toxic and is not suitable for use in the production process, recently disclosed examples include etching of a system in which various additives are added to an inorganic basic aqueous solution. There are many solutions.

  These conventional methods of patterning by wet etching of a polyimide film include a method of using a metal for a pattern mask (Japanese Patent Laid-Open No. 5-283486), a method of using a negative liquid resist for solvent development and solvent stripping (Japanese Patent Laid-open No. 5-301981), a method using a positive type liquid resist for solvent development and solvent removal (Japanese Patent Laid-Open Nos. 51-27464, 53-49068, 53-49068, JP-A-57-65727 and JP-A-58-74041). These conventional methods of patterning by wet etching of a polyimide film have the effect of reducing the time required for patterning the insulating layer.

  In addition, laminates that use polyimide as an insulating layer are often thin and have low rigidity, so they have the problem of poor handling properties compared to conventional rigid glass epoxy substrates. This is a major constraint.

JP-A-6-164084 JP-A-4-168441 Japanese Patent Laid-Open No. 50-4577 JP 58-103531 A JP-A-57-65727 JP 58-74041 A JP 58-96632 A Japanese Patent Laid-Open No. 3-101228 Japanese Patent Laid-Open No. 5-190610 JP-A-5-202206 JP-A-7-157560 JP-A-5-283486 JP-A-5-301981 Japanese Patent Laid-Open No. 51-27464 JP-A-53-49068 JP-A-53-49068 JP-A-57-65727 JP 58-74041 A JP-A-6-164084 JP-A-60-157286 JP-A-10-97081 JP-A-10-195214

Iwata, Haraen, Electronic Materials, 35 (10), 53 (1996) Proceedings of the 7th meeting of the Japan Institute of Electronics Packaging Published 1999

  However, in the method of etching polyimide using the metal layer as a pattern mask, the metal layer is etched so as to have a final insulating layer pattern shape, and the insulating layer is formed using the etched metal layer as a pattern mask. After etching, it was necessary to re-pattern the metal layer into the desired wiring shape by etching. In other words, this method requires a total of two metal etching processes, and the etching solution touches the metal during polyimide etching, which causes deterioration of the metal layer.

  In addition, when a resist pattern is prepared using a solvent developing / peeling type liquid resist, an organic solvent is required for the developer and the stripping solution. It was. In addition, when a solvent developing / peeling type liquid resist is used, it has been difficult to stably form a coating film having a uniform thickness for the following reason. That is, an electronic component such as a suspension for a hard disk drive is manufactured by applying a liquid resist to a substrate having low rigidity and drying it, and it is difficult to produce a coating film having a uniform thickness. Electronic parts such as hard disk drive suspensions require high-precision patterning, but when manufacturing resist films by coating, the coating and drying process is very strict in order to make the coating film accurate and constant in thickness. Needed to be managed.

  Basically, resists that can be developed with basic aqueous solution and stripped with basic aqueous solution will be stripped from the laminate, which is the substrate, due to the alkaline component of the etchant when a polyimide etchant containing an inorganic basic aqueous solution is used. Therefore, it was considered difficult to produce an electronic component by etching the laminate using such a resist.

  Moreover, the polyimide wet etching technique currently disclosed is mainly a laminate using an insulating layer composed of a single polyimide layer, and a wet laminate obtained by laminating a plurality of polyimide layers. There are only a few reports of examples of processing by etching (Japanese Patent Laid-Open No. 6-164084). This is because when a plurality of layers of polyimide are laminated, the etching characteristics of each layer are different, so that a good cross-sectional shape cannot be obtained by wet etching.

  Since the hard disk suspension is an essential element for the suspension for hard disks, a laminate produced by sandwiching a low-expansion polyimide film with an adhesive resin layer on both sides between the conductor foil and the stainless steel foil and pressing them Or, a plurality of polyimide layers are laminated on a stainless steel foil, and the laminate is further manufactured using a laminate in which a conductor layer is formed by thermocompression bonding. Therefore, facing each of the above problems, it has not been possible to produce a suspension by patterning a polyimide layer by wet etching.

  Therefore, the present invention is low in manufacturing an electronic component by wet etching a laminate composed of a conductive inorganic layer-insulating layer-conductive inorganic layer or a laminate composed of a conductive inorganic layer-insulating layer. Providing a manufacturing method for each sheet (sheet) of the laminate, which eliminates the problem of the prior art described above without using an organic solvent having a problem in disposal due to cost. The purpose is to do.

  An additional object of the present invention is to realize a manufacturing method that enables etching of a conductive inorganic layer in one time in order to prevent deterioration of the conductive inorganic layer, and to provide a chemical solution used for developing and stripping resist to the environment. Provided is a method for manufacturing an electronic component in which wet etching using a resist can be applied to an insulating layer having a single-layer structure or a laminated structure of two or more insulating unit layers without using a heavy organic solvent.

  Further, an additional object of the present invention is to provide a method for manufacturing an electronic component that has a good cross-sectional shape after wet etching and has a high etching accuracy, an electronic component obtained by the manufacturing method, and a suspension for a hard disk I will provide a.

  Further, an additional object of the present invention is to enable wet etching of the laminate using a dry film resist, in particular, development with an aqueous solution, in particular, development with a basic aqueous solution and stripping with a basic aqueous solution. is there.

The method of manufacturing an electronic component according to the present invention includes conducting a single wafer laminate comprising a conductive inorganic layer-insulating layer-conductive inorganic layer or conducting a single wafer laminate comprising a conductive inorganic layer-insulating layer by wet etching. A method for manufacturing an electronic component in which an insulating layer is patterned by wet inorganic patterning, followed by wet etching, wherein the insulating layer in the laminate can be wet etched and has a single layer structure or a laminate of two or more insulating unit layers In the structure, all layers are polyimide resin, and the patterning of the insulating layer by wet etching is performed by laminating a dry film resist on the laminate obtained by patterning the conductive inorganic layer by surface pressing under reduced pressure. By wet etching the resulting dry film resist laminate. The dry film resist has fine irregularities formed on the surface, the fine irregularities are provided by embossing, and the dry film resist can be developed with a basic aqueous solution and peeled off with a basic aqueous solution. The dry film resist laminate can be wet-etched by exposing, developing and patterning the dry film resist laminate, and then improving the resistance of the dry film resist to the etchant of the insulating layer. As a characteristic feature, a treatment selected from ultraviolet irradiation treatment, heat treatment, and a combination of ultraviolet irradiation treatment and heat treatment is performed.

  In the method for manufacturing the electronic component, it is a preferable aspect that the dry film resist can be developed with an aqueous solution, particularly, a basic aqueous solution, and can be peeled off with the basic aqueous solution. By performing development with a basic aqueous solution and peeling with a basic aqueous solution, the apparatus cost can be reduced, and there is an advantage that there is no problem of processing of a used organic solvent.

  As a result of investigating the resistance of various dry film resists to various etching solutions, the etching conditions, dry film resist film thickness, etc. for the basic aqueous solution development / basic aqueous solution peeling type dry film resists should be optimized as follows. For example, it has been found that depending on the material of the dry film, it has resistance to an etching solution. Moreover, it discovered that it was similarly resistant also about the dry film resist of lactic acid aqueous solution development and lactic acid aqueous solution peeling type other than basic aqueous solution development and basic aqueous solution peeling.

  That is, in order to impart such etching resistance of a dry film to a laminate, a dry film resist is laminated on a laminate subjected to patterning of a conductive inorganic layer under reduced pressure by a vacuum press. It is desirable to perform wet etching on the laminate of the dry film resist. By subjecting the dry film resist to surface pressing on the laminate under reduced pressure, the problem of warping after lamination is solved.

  The occurrence of warping after laminating this dry film resist occurs as follows. The three-layered laminate that is usually used is made by thermocompression bonding under reduced pressure in pursuit of a high degree of flatness, so it is not a long product wound up in a roll shape but a sheet form for each sheet. . When a dry film resist is laminated on a substrate that has been subjected to metal patterning by a roll laminator to form an insulating layer pattern in the laminate, the laminate itself warps because the laminate itself is thin and lacks rigidity. As a result, there has been a problem that the misalignment between the mask and the resist during exposure to the resist becomes large. Wet etching of insulating layers is characterized by better dimensional accuracy of patterning than plasma etching, which is the current dry process, so such misalignment is a major problem. Is very important in establishing a wet etching process.

  Therefore, the present invention solves the problem of warping after lamination by subjecting the dry film resist to surface pressing under reduced pressure. However, when a normal dry film resist is used, in the case of surface pressing, since the wiring of the conductive inorganic layer is formed on the insulating layer, the wiring of the conductive inorganic layer is uneven. Alternatively, there is a problem that bubbles may be encapsulated between the dry film resists at the convex wrinkles.

  In order to prevent the inclusion of bubbles as described above, it is desirable that fine irregularities be formed on the surface of the dry film resist. The generation of bubbles can be suppressed by laminating a dry film resist having irregularities on the surface so that the irregularities are directed to the irregularity side (that is, the wiring side) of the conductive inorganic layer. In other words, the unevenness creates an escape area for bubbles and prevents the bubbles from being embraced.

  In addition, in order to impart the etching resistance as described above to the laminate, the dry film resist laminate is exposed, developed and patterned, and as a process for improving the resistance of the dry film resist to the etchant of the insulating layer, It is desirable to perform a treatment selected from ultraviolet irradiation treatment, heat treatment, and a combination of ultraviolet irradiation treatment and heat treatment.

  Moreover, in order for the above conditions to exhibit an effect, it is desirable that the thickness of the insulating layer of the laminate is 3 μm to 500 μm. If the insulating layer is thicker than 500 μm, the time required for etching becomes longer, the dry film resist is invaded by the etching solution, and the shape of the dry film resist cannot be maintained, and if it is less than 3 μm, the insulation reliability is low. Because it becomes.

  Moreover, in order to prevent the exposure of the inorganic layer and improve the etching shape, the thickness of the dry film resist is 1.1 to 5 times the thickness of one conductive inorganic layer of the laminate as a raw material. It is desirable to be.

  Further, in order to impart the etching resistance as described above to the laminate, the time required for wet etching of the insulating layer is 10 seconds to 30 minutes, preferably 10 seconds to 15 minutes, more preferably 10 seconds to 5 seconds. Desirably within minutes.

  From the viewpoint of productivity and etching shape stability, it is desirable that the temperature during wet etching of the insulating layer be 10 ° C. or higher and 120 ° C. or lower.

  Dry film resists that can be developed and stripped with a basic aqueous solution are currently the most versatile and are inexpensive, have many varieties, and have a wide range of choices. Many devices are also commercially available for development and stripping processes. Therefore, it is easy to obtain and the price is low. Further, in the case of an inorganic basic aqueous solution, the waste liquid can be easily treated, so that the cost for the entire process can be greatly reduced as compared with the case of using a solvent developing / solvent peeling type liquid resist.

  The laminate of the present invention is particularly useful for a suspension for a hard disk drive, because it is a method of manufacturing an electronic circuit component, and a laminate having a good cross-sectional shape after wet etching and a good etching accuracy.

  According to the present invention, since the conductive inorganic layer is patterned by wet etching and subsequently the insulating layer is patterned by wet etching, etching can be performed in a shorter time and productivity is better than dry etching. In particular, products such as hard disk drive suspensions, where the area of the insulating layer removed by etching is large and fine patterns are required, are extremely effective in applying wet etching. Therefore, it is a manufacturing method with good workability and few defects.

  In addition, high-precision patterning is required for electronic components such as hard disk drive suspensions, but a liquid resist is applied to a non-rigid substrate for producing hard disk drive suspensions and the like, so that the resist film is accurate. Although it is difficult to achieve a uniform thickness, it requires very strict management in the coating and drying process, and is not suitable for fine etching. In the present invention, a dry film resist is used for patterning the insulating layer. Therefore, the use of a dry film having a constant film thickness has the advantage that process management is easy to form a resist and that it is suitable for fine etching.

  When manufacturing an electronic component of the present invention using a dry film resist having fine irregularities formed on the surface during wet etching, the fine irregularities create a space for air bubbles and laminate the dry film resist. Even so, it is possible to prevent entrapment of bubbles, and thus the etching resistance of the laminate is improved.

  In the method of manufacturing an electronic component according to the present invention, since a laminate of a dry film resist can be developed with a basic aqueous solution and stripped with a basic aqueous solution, the manufacturing equipment is inexpensive and can be disposed of. There is an advantage of not using a problematic organic solvent.

  In the method for manufacturing an electronic component according to the present invention, when a dry film is laminated under reduced pressure by a vacuum press on a laminate in which a conductive inorganic layer is patterned, warpage after lamination even in lamination for each sheet unit. And the inclusion of bubbles can be prevented.

  In the method for producing an electronic component of the present invention, after the dry film resist laminate is exposed, developed and patterned, an ultraviolet irradiation treatment, a heat treatment, and a treatment selected from a combination of the ultraviolet irradiation treatment and the heat treatment are performed. In this case, the resistance of the dry film resist to the etchant of the insulating layer can be improved.

  When the time required for wet etching of the insulating layer is 10 seconds or more and 30 minutes or less, preferably 10 seconds or more and 15 minutes or less, more preferably 10 seconds or more and 5 minutes or less, etching is performed with an etching solution of a strongly basic aqueous solution. However, the dry film resist does not peel at the time of etching, and accurate wet etching can be performed.

  When a dry film resist having a thickness 1.1 to 5 times as thick as the unevenness on the surface of the laminate is used, the convex portions of the laminate may be exposed through the dry film resist after laminating the dry film resist. And a good etching pattern shape can be obtained.

It is a process figure which shows the manufacturing method of the electronic component by wet etching using the laminated body which formed the conductive inorganic layer of copper in the single side | surface of the polyimide insulating layer, and the conductive inorganic layer of SUS in the other side. It is an electron micrograph of a sample that has been successfully etched. It is an electron micrograph of the sample which copper alloy foil exposed and the etching defect generate | occur | produced.

1 Insulating layer 2, 3 Conductive inorganic layer 4, 5 Dry film resist

  Specific examples of preferred embodiments will be outlined below with reference to process diagrams for the electronic component manufacturing method of the present invention. However, the present invention is not limited to this. FIG. 1 shows a method of manufacturing an electronic component by wet etching using a laminate in which a copper conductive inorganic layer 3 is formed on one side of a polyimide insulating layer 1 and a SUS conductive inorganic layer 2 is formed on the other side as a starting material. FIG.

The layer structure indicated by (a) is a laminate of starting materials. A dry film resist 4 is laminated on the conductive inorganic layers 2 and 3 on the front and back surfaces of the laminate by surface pressing to obtain a laminate having a laminate structure shown in (b). The laminate is exposed with a mask such that the conductive inorganic layers 2 and 3 have a desired pattern, then developed with an aqueous Na ₂ CO ₃ solution, and a resist pattern in the state shown in (c) is formed. Form. Next, the conductive inorganic layers 2 and 3 are etched with an FeCl ₃ aqueous solution to form an etching pattern of the conductive inorganic layers 2 and 3 according to the resist pattern in the state shown in FIG. Next, the resist is dissolved and peeled with an aqueous NaOH solution or an aqueous KOH solution to obtain an etching pattern of the conductive inorganic layers 2 and 3 in the state shown in FIG. Next, the dry film resist 5 is laminated by surface pressing on the front and back surfaces of the laminate of the conductive inorganic layers 2 and 3 in the state (e) to obtain a laminate having a laminate structure shown in (f). The laminate is covered with a mask so that the insulating layer 1 has a desired pattern, and then developed with a Na ₂ CO ₃ aqueous solution to form a resist pattern in the state shown in (g). Next, by etching the insulating layer 1 with a basic aqueous solution, an etching pattern of the insulating layer 1 according to the resist pattern in the state shown in (h) is formed. Next, the resist is dissolved and peeled with an aqueous NaOH solution or an aqueous KOH solution to obtain the electronic component of the present invention in which the etching pattern in the state shown in (i) is formed.

  Next, each component of the present invention will be specifically described.

Laminated body The laminated body used for this invention is a layer structure which consists of a conductive inorganic substance layer-insulating layer-conductive inorganic substance layer or an insulating layer-conductive inorganic substance layer. Here, the conductive inorganic layer used means a conductive material layer that is not an organic substance. For example, a pure metal layer such as copper or iron, an alloy layer such as stainless steel, and the surface of these metal layers are treated. Material layers, single crystal silicon layers, inorganic semiconductor layers, metal oxide layers, and the like, and when the conductive inorganic layers are formed on both sides of the insulating layer, the respective conductive inorganic layers may be the same. And may be different. In particular, when used as an electronic component, copper, copper alloy, iron, nickel, stainless steel and the like are preferably used. These conductive inorganic layers preferably have a thickness in the range of 0.1 μm to 1 mm, and more preferably in the range of 0.1 μm to 200 μm, particularly when the conductive inorganic layer is a metal.

  When the electronic component obtained by the method for manufacturing an electronic component according to the present invention is used for a suspension for a hard disk drive, it is particularly limited as long as one of the conductive inorganic layers in the laminate as a starting material is stainless steel. Although not intended, SUS304 is preferable from the viewpoint of the spring characteristics and dimensional stability required for the suspension, and more preferably, a tension annealing treatment is performed at a temperature of 300 ° C. or higher. The preferred thickness range of the stainless steel foil is 10 to 70 μm, more preferably 15 to 30 μm.

  Examples of the other conductive inorganic layer of the laminate as a starting material include a copper foil and a copper alloy foil having a thickness of 3 to 20 μm. The copper alloy foil is an alloy foil made of different elements such as copper and nickel, silicon, zinc, tin, beryllium, etc. and having a copper content of 80% or more.

  These stainless steel foils and copper alloy foils may be subjected to chemical or mechanical surface treatment for the purpose of improving adhesive strength and the like.

  The insulating layer in the laminate is not particularly limited as long as it is a substance having insulating properties, but it is preferable that at least one polyimide resin is included from the viewpoints of insulating properties and heat resistance in a thin film. In addition, a plurality of insulating unit layers constituting the insulating layer may be laminated for the purpose of improving the adhesiveness with the conductive inorganic layer. For example, an adhesive insulating layer may be included. In that case, it is preferable that all the layers are polyimide from a heat resistant and insulating viewpoint. Each of these layers may have a different composition depending on the required characteristics, or a plurality of layers having the same composition may be used. As such an example, a laminate composed of stainless steel-adhesive polyimide A-low expansion polyimide-adhesive polyimide B-copper is mentioned, and the adhesive polyimides A and B are respectively conductive inorganic layers that are adherends. However, since it is different from stainless steel and copper, it has a different composition from the necessity of adjusting the composition to adhere well to each adherend.

  Also, from the viewpoint of preventing warping of the substrate, it is preferable to use at least one of the insulating layers having a coefficient of thermal expansion (linear thermal expansion coefficient) that is relatively similar to that of the conductive inorganic layer (Japanese Patent Laid-Open No. Sho). 60-157286), and the allowable range of the difference in thermal expansion coefficient is ± 15 ppm. Furthermore, since the conductive inorganic substance generally has a coefficient of thermal expansion of 30 ppm or less, an insulating layer having a coefficient of thermal expansion of 30 ppm or less is preferably used. Moreover, when it is desired to suppress the occurrence of warpage more strictly, the total thickness of the insulating layer of 30 ppm or less is preferably 1/2 or more of the total thickness of all the insulating layers.

  In particular, the etching characteristics of a polyimide layer having a plurality of insulating layers in the laminate are important. When the insulating layer in the laminate of the present invention is composed of two or more insulating unit layers, the ratio of each layer having a high etching rate to a small one during wet etching is 6: 1 to 1: 1, preferably 4: Those within the range of 1: 1 to 1: 1 are desirable. If each insulating unit layer having an etching rate within this range is selected, the insulating layer has a good etching shape. Therefore, since the wet etching can be performed with high accuracy even in a laminate for wireless suspension, which has conventionally been required to have strict specifications, etching can be performed in a shorter time and productivity is better than dry etching.

  The total thickness of the insulating layer is preferably in the range of 3 μm to 500 μm. Furthermore, from the viewpoint of productivity and from the viewpoint of the resistance of the dry film resist to the etching solution, the wet etching processing time is preferably 10 seconds or more and 30 minutes or less, more preferably 15 minutes or less. On the other hand, exceeding 30 minutes leads to poor productivity. If the etching rate under the conditions for wet etching is large and the insulating layer having a thickness of 500 μm or more can be etched in 30 minutes, the thickness of the insulating layer may be 500 μm. In the case where etching cannot be performed, the allowable range is a thickness capable of etching the insulating layer over 30 minutes. Specifically, when the etching rate of the insulating layer is 20 μm / min, the allowable range of the thickness of the insulating layer is up to 600 μm, and when the etching rate is 2 μm / min, the allowable range is up to 60 μm. is there.

  Taking wet etching of an insulating layer as an example of etching of polyimide as an insulating layer with a basic aqueous solution, an imide bond reacts with a hydroxide ion in the solution to open a ring to become a polyamic acid. Even in this state, it is easier to dissolve in a basic aqueous solution than in the case of polyimide, but the solubility is improved by further hydrolyzing the amide group of the amic acid into hydroxide ions and decreasing the molecular weight of the polymer. If the molecular chain has a group that is easily hydrolyzed, it may be hydrolyzed. In general, in the case of insulating layers made with the same structure and the same manufacturing conditions, the speed is approximately proportional to the number of times the hydroxide ions collide with the polyimide imide bond, which is thermodynamically related to the temperature. It increases exponentially with.

  Due to this mechanism, when the etching rate is a linear polymer, it seems that the molecular weight is not so much affected within the practical molecular weight range. There are data to reinforce the hypothesis.

  In the laminate as a starting material used in the present invention, the adhesive insulating layer constituting the insulating layer is mainly polyimide or a similar resin, but is not particularly limited, and is a resin having heat resistance and insulating properties. It only has to be (regardless of the presence or absence of imide bonds). In the present invention, the adhesive polyimide is a polyimide having an adhesion strength of 100 g / cm or more in a 90 ° peel test with an adherend, and thermoplastic polyimide is mainly used, but is not particularly limited.

  The laminate as a starting material used in the present invention is formed by coating and laminating one or more solutions of the insulating layer directly on the conductive inorganic layer to form an insulating layer and laminating the other conductive inorganic layer. After that, even the one produced by thermocompression bonding (casting method) is prepared by forming an adhesive insulating layer on a core film as an insulating layer prepared in advance, and laminating a conductive inorganic layer on the top and bottom and thermocompression bonding. As long as the layer structure of the final laminate is the same, such as the one that has been formed (film method) or the formation of an adhesive insulating layer on an insulating film and then the formation of a conductive inorganic layer by vapor deposition, sputtering, plating, etc. Regardless of its production method, it can be selected appropriately according to the required performance of the target product.

  When the target electronic component is an essential component that cannot be formed by plating, such as rolled copper foil or stainless steel, use a laminate made by a method of forming a conductive inorganic layer by thermocompression bonding. In the case where patterning of a very fine conductive inorganic layer having a wiring width of 1 μm or less is required, it is preferable to use a laminate in which the conductive inorganic layer is thinly formed by sputtering or plating.

  Although the thickness of the whole laminated body including a conductive inorganic substance layer is various according to the use to be used, the range of 5 micrometers-2000 micrometers is preferable. In particular, when all the conductive inorganic substances in the laminate are metals, a range of 5 μm to 1000 μm is preferable, and a range of 5 to 500 μm is particularly preferable.

Dry Film Resist For the dry film resist in the present invention, a substance whose solubility in a developer is changed by irradiation with ultraviolet rays (electromagnetic waves) is used. A dry film resist is a photosensitive resin composition that can be patterned in exposed and unexposed areas by irradiating ultraviolet rays (electromagnetic waves) through an exposure mask with a desired pattern. Say what. There are a positive type in which the exposed portion elutes in the developer and a negative type in which the unexposed portion elutes in the developer. Either one may be used in the present invention as long as the required physical properties described below are satisfied.

  The dry film resist in the present invention is preferably one that can be developed and peeled off with an aqueous solution, particularly a basic aqueous solution. However, the dry film resist is resistant to an etching solution and can retain the pattern shape while the insulating layer is wet etched. If it can do, it will not specifically limit. Examples of the basic aqueous solution that can be developed and peeled include the Sanfort series (trade name) manufactured by Asahi Kasei Kogyo Co., Ltd., the ALPHA series (trade name) manufactured by Nichigo-Moton, and the LAMINAR series (trade name). Also, a commercially available lactic acid solution developing / lactic acid solution peeling type dry film resist SFP-00GI-25AR (trade name: manufactured by Nippon Steel Chemical Co., Ltd.) can be used.

  In the wet etching of the insulating layer in the present invention, unevenness such as wiring of the conductive inorganic layer is often formed on the surface of the insulating layer. In that case, the thickness of the dry film resist used is the thickness of the conductive inorganic layer. It is desirable that it is 1.1-5 times. If it is less than 1.1 times, the convex portion of the substrate may break through the dry film resist and be exposed after the dry film resist is laminated, resulting in a defective etching shape. For the purpose of stabilizing the pattern shape and the purpose of resolving the fine pattern, the upper limit of the film thickness is preferably up to 5 times the thickness of the conductive inorganic layer on the insulating layer. In simple terms, a good pattern shape can be obtained if the film thickness of the dry film resist is in the range of 1.1 to 5 times the thickness of the conductive inorganic layer on the pattern forming side with the dry film resist. .

  Usually, the commercially available dry film resist has an aspect ratio of about 2 to 1, and it is more advantageous to thin the thin line for patterning. However, since there is the above problem, it is provided in the laminate. It must be thicker than the conductive inorganic layer.

  As a dry film resist laminating method, a known laminating method such as surface pressing can be used. However, the laminate used in the present invention has a maximum insulating layer thickness of 500 μm, and preferably 300 μm or less. In the state where the conductive inorganic layer is patterned into a desired shape, the rigidity of the substrate is low. Therefore, when the laminate is laminated by a roll press, the substrate warps when processed for each sheet. When the substrate is warped, a large shift occurs in alignment when exposure is performed thereafter. Since this shift causes a shift between the pattern of the conductive inorganic layer and the pattern of the insulating layer, it must be made as small as possible. Therefore, when laminating a dry film resist on a substrate on a sheet, the use of a surface press is an essential requirement for producing a product as designed with high accuracy.

  Also, when laminating air bubbles when laminating a dry film resist on an etched conductive inorganic layer, for example, if there are bubbles in the conductive inorganic layer due to etching, the air bubbles When the is encapsulated, the part becomes poor adhesion, and the etching shape becomes defective. Since wet etching has an etching rate several tens of times higher than that of plasma etching, which is a dry process, if there is such an adhesion defect, it is easy to etch even a portion that is not normally etched, and the pattern defect is more extensive than the dry process. Therefore, in the present invention, this laminating step is performed under reduced pressure or vacuum, preferably 80 KPa (≈600 mmHg) or less, more preferably 40 KPa (≈300 mmHg) or less, and most preferably 6.7 KPa (≈50 mmHg) or less. It is desirable to remove bubbles by using vapor pressure.

  By the way, when a dry film resist having a smooth surface is used, about 20% or more of the surface of the substrate may become bubbles even if surface pressing is performed under reduced pressure. In such a case, if a dry film resist with fine irregularities on the surface is used and laminated so that the irregularities are directed to the substrate side, the fine irregularities become passages for bubbles to escape, and this phenomenon It does not occur and is very effective in removing bubbles.

  In other words, when laminating a dry film resist by a process for each sheet, in order to produce a product with good dimensional accuracy, surface pressing under reduced pressure and a dry film resist with irregularities on the surface are applied. It becomes a preferable aspect to use.

  The unevenness applied to the dry film resist surface preferably has a surface roughness Rz in the range of 0.5 μm to 50 μm, and the method for forming the unevenness is a dry film by applying or molding a photosensitive resin composition. After forming the resist, it may be embossed, or by applying a solution of the photosensitive resin composition to a film with unevenness in advance and drying it to obtain a dry film resist with unevenness formed. However, the method is not particularly limited.

The conditions for laminating the dry film resist are preferably carried out at a temperature in the range of 20 to 100 ° C. and a pressing pressure in the range of 0.05 to 0.3 MPa (0.5 to 3 kgf / cm ² ). The atmosphere at that time is a reduced pressure or vacuum state, preferably 80 KPa (≈600 mmHg) or less, more preferably 40 KPa (≈300 mmHg) or less, and most preferably 6.7 KPa (≈50 mmHg) or less. Is desirable. The vacuum suction time is adjusted according to the sheet size of the laminate to be processed, but the time is set so that no bubbles remain between the dry film resist and the laminate sheet during pressure bonding. The laminating conditions vary depending on the Tg of the dry film resist to be used, and the laminating is performed at a temperature that can sufficiently cover the pattern of the conductive inorganic layer. At this time, it should be noted that if the temperature is too high, the sensitivity during exposure becomes unstable.

  The development and stripping of the dry film resist are preferably carried out under the recommended conditions using a developer or stripping solution corresponding to the dry film resist to be used, but are not particularly limited. As mentioned above, from the viewpoint of waste disposal, development with an aqueous solution, preferably a basic aqueous solution, particularly preferably an inorganic basic aqueous solution is desirable. The aqueous solution in the present invention may be a liquid containing water as a main component, and may contain less than 50% by weight of an organic solvent such as an aliphatic alcohol, an aromatic alcohol, or an organic polar solvent in accordance with development and peeling conditions. Good. The developing method may be a dip method, an air spray method, or a liquid spray method, and is not particularly limited.

  When dry film resist is used for polyimide wet etching, the etching solution contains a highly reactive component at a high concentration, so the dry film resist holds the pattern in other cases. It is difficult compared. In such a case, a dry film resist is laminated, and after exposure and development, the pattern is formed and heated, or in the case of a negative type dry film resist, again with ionizing radiation, preferably with ultraviolet rays. Then, the pattern of the dry film resist becomes strong, and the time for retaining the shape becomes long even when it comes into contact with the etching solution.

  The heating conditions are 30 ° C. to 200 ° C., preferably 70 ° C. to 150 ° C., and the treatment time is suitably 10 seconds to 20 minutes. Examples of the method include, but are not particularly limited to, a method of standing on a hot plate, a method of putting in an oven, a method of treating with hot air, and a method of using an infrared heater.

  In addition, when pattern retention is improved by irradiating ultraviolet rays (electromagnetic waves) after forming the resist pattern, it is preferable to irradiate with energy of 5 mJ or more at the same wavelength as that during pattern exposure.

Etching solution As the etching solution used in the present invention, various etching solutions as described in the section of the prior art can be used. However, the method of manufacturing an electronic component according to the present invention aims at high productivity, low process cost (equipment cost / maintenance management cost / waste disposal cost), and low toxicity. It is desirable that the liquid has low toxicity and long life. It is preferable that the highly toxic hydrazine is not included, but may be included as an additive so long as it is 10 wt% or less by weight with respect to the etching solution. If the amount of hydrazine exceeds 10%, the shape when etching is likely to become unstable, and the management of the process becomes difficult. This is because, as described in JP-A-5-301981, hydrazine has an unstable etching behavior, and a lower hydrazine content is preferable in terms of process management and working environment.

  The etching solution used in the present invention must have an etching rate sufficient to etch the polyimide within a time in which the dry film resist to be used can keep its shape. Specifically, basic aqueous solutions mainly composed of inorganic alkali disclosed in JP-A-10-97081 and JP-A-10-195214 are most preferable. The etching solution that can be used in the present invention basically includes urea or an organic polar solvent added to an aqueous solution of inorganic alkali, aliphatic amine (diamine), aliphatic alcohol, aliphatic amino alcohol alone or a mixture thereof. The pH is preferably greater than 9.

  The processing temperature in the etching may be a temperature range higher than the freezing point of the etching solution to be used or the temperature at which precipitation occurs and lower than the boiling point, but from the viewpoint of productivity and process control, 10 ° C to 120 ° C, Preferably they are 30 to 95 degreeC, More preferably, it is 50 to 90 degreeC. In the case of an etchant containing a component that volatilizes at the processing temperature, the composition of the etchant may change if the process is continued for a long time. Although it is preferable to carry out at the temperature which does not volatilize, it is not necessary to carry out at that temperature.

  The smaller the temperature distribution in the etching bath is, the better. However, it is preferably maintained within a range of ± 1 ° C., more preferably within a range of ± 0.5 ° C.

  From the knowledge so far, it has been confirmed that the higher the temperature, the higher the etching rate exponentially from the mechanism of polyimide wet etching. The higher the etching rate, the greater the difference in etching rate with respect to temperature. Therefore, if there is a temperature distribution in the etching bath, the variation in pattern accuracy within the substrate surface increases. This is particularly remarkable when the etching rate of the insulating layer is high, and reducing the temperature distribution as much as possible is effective in performing uniform processing.

  Etching methods include dip method, air spray method, submerged spray method, dip + ultrasonic irradiation method, etc., but in the case of air spray method, the content components from the etchant often volatilize, Management becomes difficult. The dipping method or the submerged spray method is preferable, and the submerged spray method is preferable in order to reduce the taper angle of the etching shape.

  In the case of irradiating ultrasonic waves in the etching solution, it is necessary to consider the ultrasonic conditions so that the dry film resist is partially peeled by the ultrasonic irradiation and the etching shape does not become defective.

  During the etching process of the stacked body, the process may be performed with the stacked body standing vertically or may be performed in a horizontal state. When the treatment is performed in a vertical position, the etching solution is sufficiently cut off when the sample is taken out from the etching bath after the etching is completed, and the loss of the etching solution is small. When the process is performed horizontally, it is possible to perform horizontal continuous conveyance, which is more suitable for mass productivity, and there is an advantage that the temperature distribution of the etching solution is reduced.

  If necessary, it is preferable to treat the surface of the laminate with a surfactant before the etching treatment to increase the affinity with the etching solution. When the etchant is mainly composed of an inorganic basic aqueous solution, the affinity with the surface of the insulating layer may not be good. In such a case, the entire laminate is etched uniformly, Treatment with an activator has an effect of improving affinity. The type of the surfactant for the purpose is not particularly limited, but when the treatment is continued in a large amount, the surfactant is gradually included in the etching solution. In such a case, when an ionic surfactant is used, a nonionic surfactant is preferable because it acts as a buffer and may deteriorate the etching solution.

  Moreover, you may perform the rinse process as needed after the process by etching liquid. If the rinsing treatment is not performed, the components of the etching solution and the etched insulating layer residue may remain on the substrate surface, which is not preferable. Examples of the rinsing liquid used for the rinsing treatment include, but are not limited to, a basic aqueous solution, a mixed solution of an organic polar solvent and water, a mixed solution of an organic polar solvent and alcohol, and water. The temperature of the rinsing process may be in the range of a temperature higher than the freezing point of the rinsing liquid to be used or the temperature at which precipitation occurs and lower than the boiling point. At this time, the rinsing process and the dry film resist peeling process may be performed at the same time by using the stripping solution in the dry film resist peeling process, which is a process after etching, as it is as a rinsing liquid.

  Examples of the organic polar solvent used in the rinse liquid include, but are not limited to, n-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, and the like. The alcohol used in the rinsing liquid may be an aliphatic alcohol such as methanol, ethanol, propanol or the like, or an aromatic alcohol such as phenol or cresol, and may have a plurality of hydroxyl groups in one molecule such as diol. It may be a substance.

Peeling of dry film resists The recommended conditions for peeling dry film resists are the recommended conditions for peeling dry film resists, but if the insulating layer used is poor in alkali resistance, use an organic basic aqueous solution such as ethanolamine. It is good to use. As a method for peeling the dry film resist, spray peeling of a chemical solution of a basic aqueous solution is usually used, but a dip method or ultrasonic irradiation may be used.

  In addition, it is often seen in laminates produced by hot pressing, but the surface of the conductive inorganic layer forming the laminate is roughened to improve adhesion, and the roughened surface is an insulating layer. When the film is transferred to the surface, the dry film resist is embedded in the roughened surface, so that it is necessary to make the conditions more severe than usual. The same applies to the case where the etching solution resistance improving process is performed.

Laminate that can be wet etched [Etchability test]
In order to produce a sample for forming an insulating layer, polyamic acid varnish manufactured by Mitsui Chemicals, Inc .: PAA-A (trade name), polyimide varnish manufactured by Shin Nippon Rika Co., Ltd .: EN-20 (trade name) are used as adhesive resins. ) Was prepared. As a low-expansion polyimide serving as a core, a polyimide film APIKAL NPI (trade name, thickness: 12.5 μm) manufactured by Kaneka Chemical Co., Ltd. was prepared. The etching liquid used for an etching test prepared Toray Engineering Co., Ltd. alkali-amine type polyimide etching liquid TPE-3000 (brand name).

  The adhesive resin varnish EN-20 (trade name) is coated on a SUS304 plate having a size of 15 cm × 15 cm with a film thickness of 100 μm by spin coating so as to have a film thickness of 20 μm to 40 μm, and dried in an oven at 180 ° C. for 30 minutes. did. Since PAA-A (trade name) is an amic acid varnish, the solvent was removed in a drying step at 120 ° C. for 15 minutes, and then a predetermined operation was performed to obtain a thermal imidized polyimide. Each dried product is cut into a length of about 1.5 cm and a width of about 2 cm, and the center is scratched with a cutter knife, and the film thickness is measured with a stylus-type film thickness meter Dektak 16000 (trade name, manufactured by Sloan Technology). The initial film thickness was measured. After that, it is immersed in a polyimide etching solution TPE-3000 (trade name, manufactured by Toray Engineering Co., Ltd.), which has been adjusted to 70 ° C. and stirred to such an extent that a vortex can be produced by a magnetic stirrer, and the initial film thickness is measured every time. Measure the film thickness at almost the same place with the stylus-type film thickness meter Dektak 16000 (trade name, manufactured by Sloan Technology), and subtract the film thickness after immersion from the initial film thickness. The amount. The amount of film reduction per minute was defined as an etching rate (unit: μm / min). The values are shown in Table 1 below.

[Etching evaluation]
To an APIKAL NPI film (trade name, manufactured by Kaneka Chemical Co., Ltd.), which is a polyimide film having a thickness of 12.5 μm, EN-20 (trade name, new) Nippon Rika Co., Ltd. polyimide varnish) was applied on both sides and dried under the aforementioned drying conditions. The obtained film was named film A with an adhesive layer.

  Similarly, PAA-A (trade name, manufactured by Mitsui Chemicals, Inc.) is applied to both sides of an APIKAL NPI film (trade name, manufactured by Kaneka Chemical Co., Ltd.) having a thickness of 12.5 μm, and a film with an adhesive layer is formed. B. Table 2 below shows the ratio of the etching rates of the films A and B with the adhesive layer.

Between each of the films A and B with the adhesive layer, a 20 μm thick SUS304HTA foil (trade name, manufactured by Nippon Steel Corporation) and a 18 μm thick (Rz = 1.5 μm) Aurin copper alloy foil C7025 (trade name) And pressure-bonded at 20 Kg / cm ² pressure at 270 ° C. for 10 minutes to produce two types of three-layer materials made of SUS: insulating layer: copper. The obtained laminate was designated as laminate A and laminate B.

[Etching evaluation of insulating layer]
Each laminate A and B obtained in the above step was immersed in a ferric chloride solution with the SUS side masked, and the copper foil was etched. Then, after drying and cutting to an appropriate size, it was immersed in an etching solution TPE-3000 (trade name) manufactured by Toray Engineering Co., Ltd., which was stirred at 70 ° C. with a magnetic stirrer. When the polyimide film was removed cleanly and the SUS surface was exposed, it was taken out. The insulating layer was wet etched by such a method.

Similarly, plasma treatment was performed at a pressure of 25 to 30 Pa, a process gas NF ₃ / O ₂ = 10/90%, and a frequency of 40 kHz, and the insulating layer was plasma etched.

  Etching is performed until it can be confirmed that the polyimide layer does not remain on the SUS, and values obtained by dividing the film thickness of the insulating layer by the time required for this etching (etching rate) are shown in Table 3 below.

  According to Table 3, wet etching has a higher etching rate than plasma etching. It was confirmed that the insulating layer can be etched in a very short time.

Platemaking evaluation [patterning of conductive inorganic layer]
A roll in which a basic aqueous solution development type dry film resist having a thickness of 50 μm is heated on both surfaces of the stainless steel layer of the laminate A and the copper alloy foil layer prepared in the etching evaluation test having a size of 300 mm × 300 mm. After laminating at a speed of 0.5 m / min with a laminator at a roll surface temperature of 105 ° C. and a linear pressure of 2 to 4 Kg / cm, the laminate was left at room temperature for 15 minutes. At this time, since there were a stainless steel layer and a copper alloy foil layer on both sides of the laminate, the laminate was flat even after laminating the dry film resist, and no warping was confirmed. Then, 100 mJ / cm < ² > exposure was carried out with the vacuum contact exposure machine using the predetermined | prescribed mask. After standing at room temperature for 15 minutes, the dry film resist was developed with a 1% by weight aqueous solution of Na ₂ CO ₃ at 30 ° C. and a spray pressure of 2 kg / cm ² for 60 seconds to form a resist pattern.

Thereafter, the stainless steel layer and the copper foil layer were simultaneously etched with a ferric chloride aqueous solution. Thereafter, the dry film resist was peeled off with a 3 wt% NaOH aqueous solution at 50 ° C. with a spray pressure of 1 kg / cm ² , and the conductive inorganic layer of the laminate A was patterned. Thus, the laminated body A in which the stainless steel layer and the copper alloy layer were patterned and the insulating layer was partially exposed was obtained.

[Selection of dry film resist]
The following operations were performed using the laminate A from which the insulating layer obtained in the above process was exposed. The laminate A was immersed in a ferric chloride solution with the SUS side masked, and the copper foil was etched. The above basic aqueous solution development type dry film resist is applied to the exposed adhesive layer surface in such a manner at a temperature of the roll surface of 105 ° C. at a rate of 0.5 m / min with a heated roll laminator at 2 to 4 kg / cm 2. After laminating at a linear pressure of 15 minutes, it was left at room temperature for 15 minutes. After that, with a parallel light contact exposure machine manufactured by ORC Manufacturing Co., Ltd., a stripe mask with a line & space of 500 μm / 500 μm and 80 μm / 80 μm is brought into close contact with the sample, and the recommended exposure amount of the dry film is single-sided exposure in the range of 30 to 200 mJ Thereafter, the sample was turned upside down, and a similar mask was brought into close contact and exposed. After standing at room temperature for 15 minutes, the dry film resist was developed with a 1% by weight aqueous solution of Na ₂ CO ₃ at 30 ° C. and a spray pressure of 2 kg / cm ² for 60 seconds. Thereafter, it was dried and immersed in an etching solution TPE-3000 (trade name) manufactured by Toray Engineering Co., Ltd., which was stirred at 70 ° C. with a magnetic stirrer. The dry film resist was peeled off at a spray pressure of 1 kg / cm ² with a 3 wt% NaOH aqueous solution at 50 ° C. with various immersion time changes. In that way, the insulating layer was wet etched into the desired shape. For dry film resist, Sunfort AQ-1558 (trade name), AQ-2058 (trade name), AQ-2538 (trade name), AQ-3038 (trade name), AQ-4038 (trade name) manufactured by Asahi Kasei Kogyo Co., Ltd. ), AQ-5038 (trade name), NPE 538 (trade name), NPE 342 (trade name) manufactured by Nichigo Morton, and SFP-00GI-25-AR (trade name) manufactured by Nippon Steel Chemical Co., Ltd. were used. However, the designated lactic acid aqueous solution was used for development of SFP-00GI-25-AR (trade name).

  For each sample, measure the dimensions of the top of the stripe pattern, and for the sake of convenience, the point where the change is abrupt is regarded as the time when the dry film resist pattern is peeled or dissolved, and the dry film resist holds the pattern shape until that time. It was time to be.

  The pattern retention time for each sample is shown in Table 4 below.

  According to Table 4, it was found that Sunfort AQ5038 (trade name) manufactured by Asahi Kasei Kogyo Co., Ltd. and NPE342 (trade name) manufactured by Nichigo Morton were relatively excellent in etching solution resistance. Further, Sunfort AQ2538 to AQ5038 (trade names) manufactured by Asahi Kasei Kogyo Co., Ltd. are only dry film resists having the same composition, and the thicknesses of the dry film resists increase as the sample number increases. According to Table 4, as the thickness increases, the pattern holding time increases. From this, it can be determined that the etching solution resistance is also improved.

Pattern Reinforcing Treatment After patterning the dry film resist, the following post-treatment was performed in order to further impart resistance to the etchant of the dry film resist. The sample used was the laminate A from which the copper alloy foil was removed in the above process, and patterned with Asahi Kasei Kogyo Sunfort AQ5038 (trade name) into stripes of L / S = 500 μm / 500 μm and 80 μm / 80 μm. Used. The evaluation method was also evaluated using the same method as when selecting the dry film resist [Heat Treatment]
An aluminum foil was laid on a hot plate heated to 120 ° C., and sample A was allowed to stand on the aluminum foil to obtain a pattern holding time. At this time, the time was changed as shown in the following table. The results of the pattern retention rate with respect to the processing time are shown in Table 5 below.

[Post-exposure processing]
Since a negative dry film resist is used, it is necessary to further strengthen the resist pattern after development. Therefore, post-exposure was performed under the following conditions to determine the pattern holding time. The pattern retention with respect to the exposure amount is shown in Table 6 below.

  According to Tables 5 and 6, the effect of heating by pattern reinforcement treatment was greater, but the effect of post-exposure by post-exposure was not as good as heat treatment. These may be appropriately selected depending on the electronic component and process to be obtained. Even in these combinations, the effect was confirmed, but the contribution of the heat treatment effect was large, and the effect of exposure was not so conspicuous.

Plate making of dry film resist for patterning insulation layers [Dry film resist]
The following were prepared as a negative dry film resist of basic aqueous solution development / basic aqueous solution peeling type. Asahi Kasei Kogyo Co., Ltd. Sunfort AQ-1558 (trade name, thickness 15 μm), AQ-2058 (trade name, thickness 20 μm), AQ-2538 (trade name, thickness 25 μm), AQ-3038 (trade name, Thickness 30 μm), AQ-4038 (trade name, thickness 40 μm), AQ-5038 (trade name, thickness 50 μm), and Nichigo Morton ALPHHO NPE538 (trade name, thickness 38 μm, with embossing treatment), NPE 342 (Thickness 42 μm, trade name, embossed).

  The sample was subjected to surface press (under reduced pressure and normal pressure) and roll press (under reduced pressure and normal pressure) by the following method to examine the appearance of the laminate A after dry film resist lamination.

[Surface press]
Laminate A is sandwiched between dry film resists (DFR) and is laminated in the order of dry film-laminate-dry film on a hot plate with a set temperature of 75 ° C. using a vacuum laminator MVLP-500 manufactured by Meiki Seisakusho. After setting, the pressure in the chamber was reduced to 30 mmHg (≈4 KPa: about 1/25 of atmospheric pressure), and then pressed at a press pressure of 10 Pa for 80 seconds. In the same manner, an internal pressure during pressing was set to normal pressure.

  In the laminated body thus laminated, air bubbles were mixed in places at the ends where the copper alloy foil and the stainless steel foil were patterned in all samples under normal pressure. In addition, when pressed under reduced pressure, the dry film resist having fine irregularities on the surface by embossing had no air bubbles mixed in, but the one that was not embossed was copper alloy foil or Air bubbles were mixed in some places at the end where the stainless steel foil was patterned. However, all samples were flat and no warping was seen.

[Roll press]
Laminate A was laminated with a roll laminator sandwiched between dry film resists and heated at a speed of 0.5 m / min at a roll surface temperature of 105 ° C. at a linear pressure of 2 to 4 Kg / cm, and then at room temperature for 15 minutes. I left it alone. Thus, when all the laminated bodies which laminated were left still on the flat metal plate, both ends floated about 1 cm-2 cm, and it was curving to the side by which the copper alloy foil was patterned. Moreover, there was no mixing of air bubbles in the case of laminating under reduced pressure. However, what was performed at normal pressure had air bubbles mixed in some places at the end where the copper alloy foil or stainless steel foil was patterned.

  In each sample, it was confirmed that the stainless steel foil (thickness 20 μm) and the copper alloy foil (thickness 18 μm) patterned from the surface of the dry film resist were not exposed. When the resist thickness was the same or small, the metal partially penetrated the dry film resist and was exposed. The evaluation results are shown in Table 7 below.

[Exposure / Development]
The laminate A obtained by laminating the dry film resist obtained in the above step is covered with a mask pattern and exposed with i-line at an exposure amount of 30 to 150 mJ / cm ² at 30 ° C. and 1 wt% Na ₂ CO _3. And spray developed. Thereby, the insulating layer processing resist pattern was formed so as to overlap with the stainless steel layer patterned on the insulating layer and the copper alloy foil layer.

  If the insulating layer processing pattern is formed only in the region where the insulating layer remains so as not to overlap, the resist pattern is also etched by wet etching, and a gap is formed between the pattern and the stainless steel layer or the copper alloy layer. Then, there is a possibility that the etching will enter and the insulating layer will not be processed. In order to prevent this, the insulating layer processing resist pattern was formed so as to overlap with the stainless steel layer or the copper alloy layer patterned on the insulating layer. In particular, when the line width of the stainless steel layer or the copper alloy layer is narrow, it is also effective in this respect to form the insulating layer processing resist pattern on the conductive layer having a narrow line width.

  At this time, the warped sample did not adhere to the mask at the time of exposure and was forced to adhere by suction. As a result, the alignment accuracy deteriorated by about 3 to 5 times that of the other samples.

[Wet etching]
The sample obtained in the above process was wet etched under the following conditions. In addition, the etching liquid tolerance improvement process of the dry film resist was not performed. As wet etching conditions, as a pretreatment, it is immersed in a 0.5% aqueous solution of Surfynol 104E (trade name) manufactured by Nissin Chemical Industry, which is a nonionic surfactant, for 30 seconds, and then sprayed horizontally in the liquid. A mold etching apparatus was used. Etching solution TPE-3000 manufactured by Toray Engineering Co., Ltd. was used as the etching solution, and the processing temperature was 80 ° C. Although depending on the etching rate of the polyimide layer with respect to the etching solution and the etching temperature, the time required for etching of each sample was about 70 to 90 seconds.

  At that time, in the sample in which bubbles were mixed in the resist pattern, the stainless steel layer, and the sample in which the copper alloy foil layer was exposed, many portions where the target shape was not etched were observed. The cause of such defects is that the wet etching has a very high etching rate, and etching is performed even by touching the etching solution. Therefore, the dry film resist completely covers the etching pattern of the copper alloy foil layer. If not, it is likely to be defective.

  FIG. 2 shows an electron micrograph of a sample that has been successfully etched, and FIG. 3 shows an electron micrograph of a sample in which etching failure has occurred. According to FIG. 3, it can be seen that the peripheral polyimide insulating layer at the base of the etching pattern of the copper alloy foil is eroded. Such a defect is caused by the insulation at the base of the conductive inorganic layer 3 or 2 when the thickness of the dry film resist 5 is less than 1.1 times the thickness of the conductive inorganic layer 3 or 2 in FIG. Occurs around layer 1.

[Post-wet etching treatment]
A sample obtained by laminating Asahi Kasei Kogyo Co., Ltd. Sunfort AQ5038 (trade name) on the laminate A and taking out the wet etching of the insulating layer was taken out of the etching bath and filled with a rinse bath having the following composition. The sample was immersed in the bat for 30 seconds and rinsed by a technique of swinging the bat. If the rinsing process is not performed, the etched polyimide residue, the etchant, etc. remain on the surface and impair the appearance. At this time, the rinsing and dry film peeling step may be performed simultaneously using the stripping solution in the dry film resist peeling step as it is.
The term “without rinsing” in Table 8 below refers to the case where the sample is left after being taken out from the etching solution.

[Peeling]
The dry film resist was peeled from the laminate by spraying a hot basic aqueous solution of 50 ° C. and 3 Wt% sodium hydroxide on the dry film resist used for patterning the insulating layer. When the insulating layer has poor alkali resistance such as polyimide, an organic basic aqueous solution such as ethanolamine is preferably used.

[Pickling, rust prevention, gold plating, solder printing]
The patterned copper alloy foil layer of the HDD wireless suspension blank formed by the above method was subjected to gold plating as a finishing work. The gold plating is performed using a cyan gold plating bath (Tempe Resist EX) manufactured by Japan High-Purity Chemical Co., Ltd. at 65 ° C. with a current density of Dk = 0.4 A / dm ² for about 4 minutes and a thickness of 1 μm. Film formation was performed.

  When each performance of the sample produced as described above was evaluated, the sample that was warped in the state of laminating the dry film resist had poor alignment accuracy, was mixed with bubbles, and was patterned. In the case where the stainless steel foil or the copper alloy foil was exposed from the dry film resist, an etching shape defect was observed. The results are shown in Table 9 below.

  The present invention relates to an insulating layer formed of a single-layered laminate having a layer structure of conductive inorganic substance-insulating layer-conductive inorganic substance or conductive inorganic substance-insulating layer, which can be patterned by a wet process. It is useful for a method of manufacturing an electronic component by a patterning process by wet etching, an electronic component itself obtained by the manufacturing method, and a suspension for a hard disk drive.

Claims (16)

Conductive inorganic material layer-insulating layer-conductive sheet layered laminate, or conductive inorganic layer-insulated layered sheet laminate by wet etching, conductive inorganic layer patterning, then wet etching An electronic component manufacturing method for patterning an insulating layer,
The insulating layer in the laminate can be wet-etched, has a single layer structure or a laminated structure of two or more insulating unit layers, and all layers are polyimide resins.
The patterning of the insulating layer by wet etching is performed by laminating a dry film resist on the laminate obtained by patterning the conductive inorganic layer by surface pressing under reduced pressure, and on the obtained dry film resist laminate. Performed by wet etching method,
The dry film resist has fine irregularities formed on the surface, and the fine irregularities are provided by embossing,
The dry film resist is developed with a basic aqueous solution and can be peeled off with a basic aqueous solution.
The dry film resist laminate is wet-etched by exposing, developing and patterning the dry film resist laminate, followed by ultraviolet irradiation as a treatment to improve the resistance of the dry film resist to the etchant of the insulating layer. A method for manufacturing an electronic component, comprising performing a process, a heat process, and a process selected from a combination of an ultraviolet irradiation process and a heat process. 2. The method of manufacturing an electronic component according to claim 1, wherein the insulating layer of the laminate as a raw material has a thickness of 3 [mu] m to 500 [mu] m. 3. The method of manufacturing an electronic component according to claim 1, wherein a thickness of the dry film resist is 1.1 to 5 times a thickness of one conductive inorganic layer of a laminate as a raw material. A method for manufacturing an electronic component. 4. The method of manufacturing an electronic component according to claim 1, wherein a time required for wet etching of the insulating layer is 10 seconds or more and 30 minutes or less. 5. 5. The method of manufacturing an electronic component according to claim 1, wherein a temperature during wet etching of the insulating layer is 10 ° C. or higher and 120 ° C. or lower. The electronic component manufacturing method according to any one of claims 1 to 5, wherein at least one of the single layer structure or the two or more insulating unit layers in the insulating layer is a low expansion polyimide having a linear thermal expansion coefficient of 30 ppm or less. Method. The method for manufacturing an electronic component according to claim 6, wherein the insulating layer has a layer structure made of adhesive polyimide-low expansion polyimide-adhesive polyimide. The method for manufacturing an electronic component according to claim 7, wherein the two adhesive polyimides are polyimides having different compositions in the insulating layer having a layer structure of adhesive polyimide-low expansion polyimide-adhesive polyimide. 9. The method of manufacturing an electronic component according to claim 1, wherein the pH of the etching solution used for etching the insulating layer is greater than 9. 10. The method of manufacturing an electronic component according to claim 1, wherein the one or two conductive inorganic layers in the laminate are all copper or a material obtained by subjecting copper to a surface treatment. . 10. The electronic component according to claim 1, wherein the one or two conductive inorganic layers in the laminate are all made of a copper alloy or a material obtained by subjecting a copper alloy to surface treatment. 11. Production method. 10. The method of manufacturing an electronic component according to claim 1, wherein the one or two conductive inorganic layers in the laminate are all made of stainless steel or a material obtained by subjecting stainless steel to surface treatment. . The two conductive inorganic layers in the laminate are one layer of stainless steel or a material obtained by subjecting stainless steel to surface treatment, and the other layer is a copper alloy or a material obtained by subjecting copper alloy to a surface treatment. Item 10. The method for manufacturing an electronic component according to any one of Items 1 to 9. 2. The two conductive inorganic layers in the laminate are one layer made of stainless steel or a material obtained by subjecting stainless steel to surface treatment, and the other layer is made of copper or a material obtained by subjecting copper to surface treatment. The manufacturing method of the electronic component in any one of thru | or 9. The electronic component produced by the manufacturing method of the electronic component in any one of Claims 1 thru | or 14. A suspension for a hard disk drive manufactured by the method for manufacturing an electronic component according to any one of claims 1 to 14.