Electroless iron-nickel plating liquid, method for manufacturing material to be plated, and anisotropic conductive sheet

Abstract

To provide an electroless iron-nickel plating liquid that can form an iron-nickel alloy film stably exhibiting a high-iron eutectoid ratio.SOLUTION: An electroless iron-nickel plating liquid includes an iron ion source, a nickel ion source, a reductant, and a complexing agent. The complexing agent includes: a monocarboxylic acid-based complexing agent having one carboxy group and two or more hydroxy groups and including a monocarboxylic acid having two or more carbon atoms or a salt thereof; and a polyvalent carboxylic acid-based complexing agent having two or more carboxy groups and one or more hydroxy groups and including a polyvalent carboxylic acid having two or more carbon atoms or a salt thereof.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an electroless iron-nickel plating solution, a method for manufacturing a material to be plated, and an anisotropic conductive sheet.

Background Art

[0002] It is known that the performance of an iron-nickel alloy film varies greatly depending on its composition (especially the iron content). In particular, an iron-nickel alloy film containing 50% by mass or more of iron (so-called Invar alloy) not only has a high magnetic permeability but also is known to have a very low coefficient of thermal expansion compared to films made of pure nickel or pure iron. Therefore, it is expected to develop iron-nickel alloy films with a high iron content for various applications such as various electromagnetic wave shields, metal masks for vapor deposition of organic EL, semiconductor substrates, anisotropic conductive sheets, and the like.

[0003] Here, as methods for manufacturing an iron-nickel alloy film, rolling, sputtering, electrolytic plating, electroless plating, etc. are common. Among these, electroless plating has the advantage that a film with a uniform thickness can be formed even on the surface of a non-conductive substrate. For example, Patent Document 1 describes an electroless plating solution for forming an iron-nickel alloy film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with conventionally known electroless plating solutions, it has been difficult to increase the iron content ratio in the iron-nickel alloy coating. For example, even in the electroless plating solution of Patent Document 1 mentioned above, the maximum iron content rate in the obtained iron-nickel alloy coating is 35% by mass. Therefore, there has been a demand for an electroless iron-nickel plating solution capable of forming an iron-nickel alloy coating with an iron content rate of 50% by mass or more.

[0006] An object of the present invention is to provide an electroless iron-nickel plating solution that can form an iron-nickel alloy coating with a high iron content rate by an electroless plating method and is stable, a method for manufacturing a material to be plated using the electroless iron-nickel plating solution, and an anisotropic conductive sheet obtained therefrom.

Means for Solving the Problems

[0007] The present invention provides the following electroless iron-nickel plating solution. [1] An electroless iron-nickel plating solution containing an iron ion source, a nickel ion source, a reducing agent, and a complexing agent, wherein the complexing agent contains a monocarboxylic acid-based complexing agent having one carboxy group and two or more hydroxy groups and having 2 or more carbon atoms or a salt thereof, and a polycarboxylic acid-based complexing agent having two or more carboxy groups and one or more hydroxy groups and having 2 or more carbon atoms or a salt thereof. [2] The electroless iron-nickel plating solution according to [1], wherein the molar ratio of the content of iron element to the content of nickel element in the electroless iron-nickel plating solution is 2:3 to 1:1. [3] The electroless iron-nickel plating solution according to [1] or [2], wherein at least one of the monocarboxylic acid-based complexing agent and the polycarboxylic acid-based complexing agent is a sodium salt or a potassium salt. [4] The content of the monocarboxylic acid complexing agent and the content of the polycarboxylic acid complexing agent in the electroless iron-nickel plating solution, relative to the total content of the iron element and the nickel element in the electroless iron-nickel plating solution, is 200 mol% or more. The electroless iron-nickel plating solution according to any one of [1] to [3]. [5] The molar ratio of the content of the monocarboxylic acid complexing agent to the content of the polycarboxylic acid complexing agent is 4:6 to 8:2. The electroless iron-nickel plating solution according to [4]. [6] The content of the monocarboxylic acid complexing agent in the electroless iron-nickel plating solution, relative to the content of the iron element in the electroless iron-nickel plating solution, is 200 mol% or more. The electroless iron-nickel plating solution according to any one of [1] to [5]. [7] The monocarboxylic acid complexing agent contains at least one compound selected from the group consisting of gluconic acid, sodium gluconate, and potassium gluconate. The polycarboxylic acid complexing agent contains at least one compound selected from the group consisting of citric acid, tartaric acid, and their sodium salts, potassium salts, and potassium sodium salts. The electroless iron-nickel plating solution according to any one of [1] to [6]. [8] Further contains a modified polyethyleneimine having a number average molecular weight of more than 1000 and less than 50000. The modified polyethyleneimine contains an ethyleneimine structural unit, one or more alkylene oxide structures having 2 or more and 12 or less carbon atoms added to the nitrogen atom of the ethyleneimine structural unit, and / or a structure derived from octadecyl isocyanate added to the nitrogen atom of the ethyleneimine structural unit. The electroless iron-nickel plating solution according to any one of [1] to [8]. [9] The modified polyethyleneimine contains a structure represented by the following general formula (1a). The electroless iron-nickel plating solution according to [8].

Chemical formula

[10] The electroless iron-nickel plating solution according to [8], wherein the modified polyethyleneimine contains an ethylene oxide structure and / or a propylene oxide structure.

[0008] The present invention provides a method for manufacturing the following workpiece to be plated.

[11] A method for manufacturing a workpiece to be plated, comprising: a step of preparing a substrate; and a step of forming an electroless plating layer on the substrate using the electroless iron-nickel plating solution according to any one of [1] to

[10] .

[0009] The present invention provides the following anisotropic conductive sheet.

[12] An anisotropic conductive sheet having a first surface located on one side in the thickness direction, a second surface located on the other side in the thickness direction, and an insulating layer having a plurality of through holes communicating the first surface and the second surface, and a plurality of conductive layers disposed on at least the inner wall surfaces of the plurality of through holes, wherein the conductive layer is an electroless plating layer containing iron and nickel, and the iron content in the electroless plating layer is 50% by mass or more.

[13]

[12] The anisotropic conductive sheet according to

[12] , wherein the insulating layer is a composite material having a heat-resistant resin portion containing a heat-resistant resin and an elastic portion having a lower elastic modulus than the heat-resistant resin portion. [Advantages of the Invention]

[0010] According to the electroless plating solution of the present invention, an iron-nickel alloy film having a high iron content can be formed by an electroless plating method. Further, the electroless plating solution is very stable and can stably form a homogeneous iron-nickel alloy film. Furthermore, according to the method for manufacturing a workpiece to be plated of the present invention, a workpiece to be plated having an electroless plating layer with a high magnetic permeability and a low thermal expansion coefficient can be manufactured. In addition, according to the present invention, an anisotropic conductive sheet having an electroless plating layer with a high magnetic permeability and a low thermal expansion coefficient is also provided. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

Figure 3

DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, specific embodiments of the electroless iron-nickel plating solution (hereinafter also referred to as "electroless plating solution"), the method for manufacturing a material to be plated, and the anisotropic conductive sheet of the present invention will be described by way of example. However, the electroless plating solution, the method for manufacturing a material to be plated, and the anisotropic conductive sheet of the present invention are not limited to these embodiments.

[0013] 1. Electroless iron-nickel plating solution The electroless plating solution according to an embodiment of the present invention contains an iron ion source, a nickel ion source, a reducing agent, a specific monocarboxylic acid complexing agent, and a specific polycarboxylic acid complexing agent.

[0014] As described above, in the conventional electroless plating solution, it has been difficult to make the iron content in the obtained iron-nickel alloy film 50% by mass or more. On the other hand, according to the electroless plating solution of the present embodiment, not only can the iron content in the obtained iron-nickel alloy film be made 50% by mass or more, but also since the electroless plating solution is very stable, a stable and homogeneous iron-nickel alloy film can be formed. The reason is not clear, but it is considered as follows.

[0015] In electroless plating solutions for forming a known iron-nickel alloy film, ferrous ions (Fe 2+ ) tend to change to ferric ions (Fe 3+ ). Therefore, even if a large amount of ferrous ion source is used, it is difficult for iron to precipitate, and the iron content in the obtained iron-nickel alloy film does not increase sufficiently. Also, since ferrous ions change to ferric ions, it is difficult to stably form a homogeneous iron-nickel alloy film.

[0016] On the other hand, the electroless plating solution of this embodiment contains two types of complexing agents, namely, a monocarboxylic acid-based complexing agent having a specific structure and a polycarboxylic acid-based complexing agent. When the electroless plating solution contains a monocarboxylic acid-based complexing agent, as verified in the examples described later, ferrous ions (Fe 2+ ) form a stable complex in the electroless plating solution and are less likely to change to ferric ions (Fe 3+ ). However, with only the monocarboxylic acid-based complexing agent, ferrous ions are hardly reduced sufficiently, and it is difficult for the deposition amount of iron to increase to a desired range. Therefore, the polycarboxylic acid-based complexing agent enhances the reducibility of ferrous ions and the depositing property of iron. Therefore, according to the electroless plating of this embodiment, an iron-nickel alloy film having an iron content of 50 mass% or more can be formed.

[0017] Note that the electroless plating solution of this embodiment may further contain components other than the ferrous ion source, nickel ion source, reducing agent, and complexing agents (monocarboxylic acid-based complexing agent and polycarboxylic acid-based complexing agent). Examples of these other components include the compound represented by the general formula (1) described later, other components such as a pH adjuster, and a solvent. Hereinafter, each component in the electroless plating solution will be specifically described.

[0018] (Ferrous Ion Source) As the ferrous ion source, any compound that can be dissolved in the solvent contained in the electroless plating solution and supply ferrous ions may be used. As the ferrous ion source, a compound capable of supplying ferrous ions (Fe 2+ ) is preferable, but within a range that does not impair the object and effects of this embodiment, a part of the ferrous ion source may contain ferric ions (Fe 3+It may contain a compound that supplies [[ID=]]. Further, the electroless plating solution of this embodiment may contain only one kind of iron ion source, or may contain two or more kinds.

[0019] Examples of the iron ion source include iron(II) sulfamate, iron(II) chloride, iron(II) sulfate, iron(II) gluconate, sodium iron(II) citrate, iron(II) acetate, etc. Among these, from the viewpoints of availability and solubility, etc., iron(II) sulfate and iron(II) sulfamate are preferred.

[0020] The amount of the iron ion source in the electroless plating solution is preferably an amount such that the amount of iron element in the electroless plating solution is 0.005 mol / L or more and 0.1 mol / L or less, and more preferably an amount such that it is 0.01 mol / L or more and 0.05 mol / L or less. When the amount of iron element in the electroless plating solution is within this range, the electroless plating solution is likely to be stable, and the deposition rate during electroless plating is likely to be stable. The amount of iron element in the electroless plating solution can be specified by spectroscopy (UV-vis), atomic absorption spectrometry, ICP, etc.

[0021] (Nickel ion source) The nickel ion source is not particularly limited as long as it is a compound that can be dissolved in the solvent contained in the electroless plating solution and can supply nickel ions. The electroless plating solution of this embodiment may contain only one kind of nickel ion source, or may contain two or more kinds.

[0022] Examples of the nickel ion source include nickel chloride, nickel sulfate, nickel sulfamate, nickel hypophosphite salt, nickel citrate salt, nickel carbonate salt, nickel acetate, etc. Among these, from the viewpoints of availability and solubility, etc., nickel sulfate and nickel sulfamate are preferred.

[0023] In addition, the amount of the nickel ion source in the electroless plating solution is preferably an amount such that the amount of nickel element in the electroless plating solution is 0.005 mol / L or more and 0.1 mol / L or less, and more preferably an amount such that it is 0.01 mol / L or more and 0.05 mol / L or less. When the amount of nickel element in the electroless plating solution is within the above range, the electroless plating solution is likely to be stable, and the deposition rate during electroless plating is likely to be stable. The method for specifying the amount of nickel element in the electroless plating solution is the same as the method for specifying the amount of iron element described above.

[0024] The ratio of the amount of the iron ion source to the amount of the nickel ion source in the electroless plating solution is appropriately selected, but it is particularly preferable that the amount of the iron ion source and the amount of the nickel ion source are adjusted so that the molar ratio of the content of iron element to the content of nickel element in the electroless plating solution is 2:3 to 1:1. When the molar ratio of iron element and nickel element in the electroless plating solution is within the above range, the amount of iron element in the obtained iron-nickel alloy film is more likely to increase.

[0025] (Reducing agent) The reducing agent may be any compound that can reduce iron ions and nickel ions during electroless plating, and is the same as known reducing agents. The electroless plating solution of the present embodiment may contain only one kind of reducing agent or may contain two or more kinds of reducing agents.

[0026] Examples of the reducing agent include dimethylamine borane (DMAB), morpholine borane (MPB), glyoxylic acid, ammonium hypophosphite, sodium borohydride, and the like. Among these, dimethylamine borane (DMAB) is preferable from the viewpoints of reducibility and the like.

[0027] The amount (concentration) of the reducing agent in the electroless plating solution is appropriately selected according to the type of the reducing agent, but is preferably 0.1 g / L or more and 20 g / L or less, and more preferably 1 g / L or more and 10 g / L or less. When the concentration of the reducing agent is within the above range, the deposition rate during electroless plating is more likely to be stable.

[0028] (Complexing agent) As described above, the electroless plating solution of the present embodiment contains two types of complexing agents: a monocarboxylic acid-based complexing agent and a polycarboxylic acid-based complexing agent.

[0029] The monocarboxylic acid-based complexing agent is a monocarboxylic acid having one carboxy group and two or more hydroxy groups and having 2 or more carbon atoms, or a salt thereof. As described above, when the electroless plating solution contains the monocarboxylic acid-based complexing agent, ferrous ions (Fe 2+ ) become very stable and it becomes difficult to change to ferric ions (Fe 3+ ). In this specification, the hydroxy groups of the carboxy group in the structure of the carboxylic acid-based complexing agent are not counted as hydroxy groups.

[0030] The number of hydroxy groups of the above monocarboxylic acid may be 2 or more, preferably 2 or more and 8 or less. Also, the carbon number of the monocarboxylic acid may be 2 or more, preferably 2 or more and 10 or less. Furthermore, the monocarboxylic acid may have a linear structure or a branched-chain structure. When the monocarboxylic acid-based complexing agent is a salt of a monocarboxylic acid, it is preferably an alkali metal salt of the monocarboxylic acid, more preferably a sodium salt or a potassium salt.

[0031] Here, specific examples of the monocarboxylic acid-based complexing agent include gluconic acid, sodium gluconate, potassium gluconate, etc. Among these, from the viewpoint of the stability of ferrous ions, gluconic acid, potassium gluconate, or sodium gluconate is preferable, and sodium gluconate is particularly preferable.

[0032] On the other hand, the polycarboxylic acid-based complexing agent is a polycarboxylic acid having two or more carboxy groups and one or more hydroxy groups and having 2 or more carbon atoms, or a salt thereof. As described above, when the electroless plating solution contains the polycarboxylic acid-based complexing agent, the iron content in the iron-nickel alloy film tends to increase.

[0033] The number of carboxy groups possessed by the above polyvalent carboxylic acid may be two or more, preferably two or more and six or less. Further, the number of hydroxy groups possessed by the polyvalent carboxylic acid may be one or more, preferably one or more and two or less. Furthermore, the number of carbon atoms of the polyvalent carboxylic acid may be two or more, preferably two or more and ten or less. Here, the polyvalent carboxylic acid may have a linear structure or a branched-chain structure. When the polyvalent carboxylic acid-based complexing agent is a salt of a polyvalent carboxylic acid, it is preferably an alkali metal salt of the polyvalent carboxylic acid, more preferably a sodium salt, a potassium salt, or a potassium sodium salt.

[0034] Specific examples of the polyvalent carboxylic acid-based complexing agent include citric acid, tartaric acid, and alkali metal salts thereof. Among these, citric acid, tartaric acid, trisodium citrate, and Rochelle salt (potassium sodium tartrate) are preferred, and trisodium citrate and Rochelle salt (potassium sodium tartrate) are particularly preferred.

[0035] Here, the molar ratio of the content of the monocarboxylic acid-based complexing agent and the content of the polyvalent carboxylic acid-based complexing agent in the electroless plating solution is preferably 4:6 to 8:2, more preferably 5:5 to 7:3. When the molar ratio of the content of the monocarboxylic acid-based complexing agent and the content of the polyvalent carboxylic acid-based complexing agent is within this range, the stability of ferrous ions (Fe 2+ ) in electroless plating increases, and the iron ions are more easily reduced by the reducing agent and more likely to precipitate.

[0036] On the other hand, the total content of the monocarboxylic acid-based complexing agent and the polyvalent carboxylic acid-based complexing agent with respect to the total content of the above iron element and the above nickel element is preferably 200 mol% or more, more preferably 200 mol% or more and 250 mol% or less. When the total content of the monocarboxylic acid-based complexing agent and the polyvalent carboxylic acid-based complexing agent is within this range, the iron ions and nickel ions in the electroless plating solution and the monocarboxylic acid-based complexing agent and the polyvalent carboxylic acid-based complexing agent are more likely to form complexes sufficiently.

[0037] Also, the content of the monocarboxylic acid-based complexing agent with respect to the content of iron element in the electroless plating solution is preferably 200 mol% or more, and more preferably 200 mol% or more and 250 mol% or less. When the amount of the monocarboxylic acid-based complexing agent with respect to the amount of iron element is within this range, the stability of the electroless plating solution is likely to increase.

[0038] (Modified polyethyleneimine) The electroless plating solution preferably contains a modified polyethyleneimine having a number average molecular weight of more than 1000 and less than 50000. When the electroless plating solution contains a modified polyethyleneimine, the plating deposition rate is likely to increase and the composition of the obtained iron-nickel alloy film is likely to be homogenized.

[0039] The above-mentioned modified polyethyleneimine is a polymer containing an ethyleneimine structural unit having an ethylene group and an amino group, one or more alkylene oxide structures having 2 to 12 carbon atoms added to the nitrogen atom of the ethyleneimine structural unit, and / or a structure derived from octadecyl isocyanate added to the nitrogen atom of the ethyleneimine structural unit.

Chemical formula

[0040] The modified polyethyleneimine can be, for example, a polymer obtained by polymerizing ethyleneimine and then adding and polymerizing alkylene oxide or octadecyl isocyanate to the main chain of the resulting polyethyleneimine by a known method. Hereinafter, the structure will be described as an example, but the structure of the modified polyethyleneimine is not limited to this structure.

[0041] The polyethyleneimine that forms the main chain of the modified polyethyleneimine may be linear or may have a crosslinked structure, i.e., a branched chain structure, formed by polymerization. Further, within a range that does not impair the object and effects of the present embodiment, the main chain of the modified polyethyleneimine may contain structural units derived from monomers other than ethyleneimine (e.g., propyleneimine, etc.). Further, the main chain of the polyethyleneimine may contain not only tertiary amino groups such that the structural units represented by the above general formula (1) have them, but also primary amino groups and secondary amino groups.

[0042] Here, when R in the above general formula (1) is an alkylene oxide structure, the modified polyethyleneimine contains a structure represented by the following general formula (1a).

Chemical formula

[0043] In the above general formula (1a), R 2 represents a hydrogen atom or an alkyl group having 1 or more and 12 or less carbon atoms. Specific examples of the alkyl group having 1 or more and 12 or less carbon atoms include a methyl group, an ethyl group, a propyl group, etc. Among these, it is particularly preferable that R 2 is a hydrogen atom.

[0044] In the above general formula (1a), m and n only need to satisfy 1000 < 100m + 50n < 50000.

[0045] On the one hand, when R in the general formula (1) is an octadecyl isocyanate group, the modified polyethyleneimine contains a structure represented by the following general formula (1b).

Chemical formula

[0046] Also, in any modified polyethyleneimine in which R in the general formula (1) has a certain structure, its number average molecular weight may be more than 1000 and less than 50000, but more preferably 1200 or more and 20000 or less. When the number average molecular weight of the modified polyethyleneimine is within this range, the composition of the obtained iron-nickel film is likely to be homogenized. The above number average molecular weight is a value measured by gel permeation chromatography (GPC) and is a value based on pullulan as a standard substance.

[0047] The amount (concentration) of the modified polyethyleneimine in the electroless plating solution is preferably 0.01 g / L or more and 10 g / L or less, more preferably 0.05 g / L or more and 5 g / L or less, and even more preferably 0.1 g / L or more and 1 g / L or less. When the concentration of the modified polyethyleneimine is within this range, the deposition rate during electroless plating is improved, and the composition of the iron-nickel alloy film is likely to be more uniform.

[0048] (Other components) The electroless plating solution may further contain a pH adjuster, a pH buffer material, a stabilizer, etc.

[0049] The pH adjuster may be any one that does not impair the plating performance, and examples thereof include sodium hydroxide, potassium hydroxide, etc. It is preferable that the electroless plating is adjusted by a pH adjuster so that the pH is 8.5 or more and 11 or less. The electroless plating solution may contain only one kind of pH adjuster or two or more kinds of pH adjusters.

[0050] In addition, the pH buffer may be any one that does not impair the plating performance, and examples thereof include sodium tetraborate, sodium carbonate, etc. The electroless plating solution may contain only one kind of pH buffer or two or more kinds.

[0051] Furthermore, examples of the stabilizer include bismuth, lead, antimony, vanadium, thiourea, sodium thiocyanate, sodium nitrobenzenesulfonate (MBS), 2-propyn-1-ol, etc. The electroless plating solution may contain only one kind of stabilizer or two or more kinds.

[0052] The electroless plating solution may further contain a reaction accelerator, and examples thereof include sulfobetaine compounds such as sulfoxypropylpyridinium betaine. The electroless plating solution may contain only one kind of reaction accelerator or two or more kinds.

[0053] Also, the electroless plating solution may contain a surfactant. Examples of the surfactant include anionic surfactants such as polyoxyethylene alkyl ether sulfate and polyoxyethylene alkyl sulfosuccinate. The electroless plating solution may contain only one kind of surfactant or two or more kinds.

[0054] The contents of these components are appropriately selected according to their respective addition purposes.

[0055] (Solvent) Electroless plating usually further contains a solvent. The solvent is not particularly limited as long as it can dissolve the above iron ion source, nickel ion source, reducing agent, complexing agent, the compound represented by the above general formula (1), and other components. Examples of the solvent include water, ketones (such as acetone), alcohols (such as methanol, ethanol, isopropanol), etc.

[0056] (Method for preparing electroless plating solution) The method for preparing the electroless plating solution is not particularly limited. For example, an iron ion source, a nickel ion source, a monocarboxylic acid complexing agent, a polycarboxylic acid complexing agent, a reducing agent, and other components can be added to the above solvent and stirred to prepare it. The addition order of each component is not particularly limited. However, in order to enhance the stability of the electroless plating solution, it is preferable to add the iron ion source or nickel ion source and the monocarboxylic acid complexing agent or polycarboxylic acid complexing agent to the solvent in advance, mix them to form a complex, and then add other components.

[0057] (Modification example) In the above, in the electroless plating solution containing an iron ion source, a nickel ion source, a reducing agent, and two specific complexing agents (a monocarboxylic acid complexing agent and a polycarboxylic acid complexing agent) as essential components, it was explained that when the modified polyethyleneimine was added, the plating deposition rate was improved and the composition of the obtained iron-nickel alloy film was likely to be homogenized. However, the above modified polyethyleneimine can also be used in an electroless plating solution that does not use the above two types of complexing agents, that is, an electroless plating solution using a known complexing agent. Even in such an electroless plating solution, by adding the modified polyethyleneimine, it is possible to improve the plating deposition rate and homogenize the composition of the obtained iron-nickel alloy film.

[0058] 2. Method for manufacturing the material to be plated The method for manufacturing the material to be plated using the above electroless plating solution can be the same as known methods. For example, a step of preparing a substrate (hereinafter also referred to as "substrate preparation step") and a step of forming an electroless plating layer (iron-nickel alloy film) on the substrate with the above electroless iron-nickel plating solution (hereinafter also referred to as "electroless plating treatment step") can be performed to manufacture the material to be plated. In this specification, the "material to be plated" refers to a member plated on a part or all of the substrate, and its type is not particularly limited. Hereinafter, each step of the method for manufacturing the material to be plated will be described.

[0059] (1) Substrate preparation step In the substrate preparation step, a substrate for plating is prepared. The shape of the substrate is not particularly limited, and it may be, for example, flat plate-shaped, film-shaped, etc., or may have a three-dimensional shape. Also, the material of the substrate is not particularly limited, and it may be, for example, resin, or may be metal, ceramic, etc.

[0060] In the substrate preparation step, it is preferable to perform known pretreatment before the electroless plating step. Examples of the pretreatment include cleaning (degreasing) with an alkaline treatment solution, etc., acid treatment with an acidic solution, treatment with a catalyst adsorption promoter (primer solution), application of a catalyst to the plating region with a catalyst-imparting agent, reduction of the catalyst with a catalyst reducing agent, etc. As the alkaline solution, acidic solution, primer solution, catalyst-imparting agent, and catalyst reducing agent, any known ones can be used. Examples of the catalyst imparted by the catalyst treatment agent include zero-valent metals, and specific examples thereof include Pd, Ag, Cu, Ni, Al, Fe, Co, etc.

[0061] Also, each treatment method can be performed by a known technique. Note that the above pretreatment may be performed on the entire surface of the substrate, or may be performed only on the region where the electroless plating treatment is to be performed.

[0062] (2) Electroless plating treatment step In the electroless plating treatment step, electroless plating is performed on a desired region using the above-described electroless plating solution. In this step, the plating region of the substrate and the electroless plating bath (electroless plating solution) composed of the above-described electroless solution are brought into contact, and iron and nickel are deposited on the surface of the plating region by a chemical reaction. The method of contacting the electroless plating bath and the plating region is not particularly limited, and only the plating region may be brought into contact with the electroless plating bath, or the entire substrate may be immersed in the electroless plating bath. When only a partial region of the substrate is the plating region, a resist or the like may be applied for masking treatment so that the electroless plating bath does not adhere to the portion other than the plating region. Also, in this step, it is preferable to stir the electroless plating bath. Examples of the stirring method include liquid circulation by a pump, rocking and stirring of the object to be plated, paddle stirring, etc.

[0063] When the electroless plating bath is brought into contact with the base material, the temperature of the electroless plating bath is preferably 25 to 70°C, more preferably 30 to 50°C. When the temperature of the electroless plating bath is 25°C or higher, an electroless plating layer can be efficiently formed. On the other hand, when it is 70°C or lower, it is difficult to affect the base material.

[0064] The contact time between the base material and the electroless plating bath is preferably 3 to 45 minutes, more preferably 10 to 30 minutes. When the contact time of the electroless plating bath is 3 minutes or more, an electroless plating layer can be efficiently formed. On the other hand, when it is 45 minutes or less, it is difficult to affect the base material. Thereby, a plated base material having a desired electroless plating layer formed in the plated region is obtained. In addition, after the contact with the above-mentioned electroless plating bath, annealing treatment or the like may be performed as necessary. The annealing treatment is preferably performed by heating at about 100°C to 150°C, and the treatment time is preferably 5 minutes to 30 minutes.

[0065] According to the above-mentioned electroless plating solution, an electroless plating layer (iron-nickel alloy film) having an iron content of 50% by mass or more can be formed. It is also possible to form an iron-nickel alloy film having an iron content of 60% by mass or more. The upper limit of the iron content of the electroless plating layer (iron-nickel alloy film) is usually 65% by mass or less.

[0066] 3. Use of the Plated Material The above-mentioned plated material can be used for various purposes. As described above, the iron-nickel alloy film having an iron content of 50% by mass or more has a high magnetic permeability and a very low thermal expansion coefficient. Therefore, the above-mentioned plated material is applicable to applications that require a high magnetic permeability and various applications that require dimensional stability.

[0067] Examples of the use of the material to be plated include an electromagnetic shield having a resin substrate containing resins such as polybutylene terephthalate, polypropylene, polyamide, etc., and an iron-nickel alloy film disposed on the resin substrate; a metal mask for manufacturing an organic EL element having a resin substrate containing a resin such as a polyimide film or polyethylene terephthalate, and an iron-nickel alloy film disposed in a pattern on the substrate; a semiconductor substrate having a ceramic substrate made of SiC, AlN, etc., and an iron-nickel alloy film disposed on the ceramic substrate; an anisotropic conductive substrate described later, etc. Hereinafter, as an example of the material to be plated, an anisotropic conductive sheet and a method for manufacturing the same will be described.

[0068] (Anisotropic Conductive Sheet) The anisotropic conductive sheet in this specification is a sheet having conductivity in the thickness direction and insulating properties in the plane direction. The anisotropic conductive sheet can be used as a probe (contact) in electrical inspection. A plan view of the anisotropic conductive sheet 10 according to an embodiment of the present invention is shown in FIG. 1A, and a partial enlarged cross-sectional view taken along line 1B-1B in FIG. 1A is shown in FIG. 1B. The anisotropic conductive sheet 10 has an insulating layer 11 having a first surface 11a located on one side in the thickness direction, a second surface 11b located on the other side in the thickness direction, and a plurality of through holes 12 communicating the first surface 11a and the second surface 11b, and a conductive layer (electroless plating layer) 13 disposed on the inner wall surface 12c of the through hole 12.

[0069] The anisotropic conductive sheet 10 is disposed between the substrate of the electrical inspection device and the inspection object in order to ensure electrical contact between the electrode of the substrate of the electrical inspection device and the terminal of the inspection object. During electrical inspection, a pressing load is applied to ensure reliable electrical connection between the substrate of the electrical inspection device and the inspection object. Therefore, the insulating layer 11 of the anisotropic conductive sheet 10 preferably has insulating properties and elastic deformability. The insulating layer 11 may be composed of, for example, a single type of resin, or may be composed of multiple layers as shown in FIG. 1B. In the embodiment shown in FIG. 11B, two heat-resistant resin layers (heat-resistant resin portions) 11B and 11C, which have a higher elastic modulus and heat resistance than the elastic layer 11A, are disposed on both sides of the elastic layer (elastic portion) 11A having a low elastic modulus.

[0070] The elastic layer 11A can be, for example, a layer containing a silicone resin. Examples of silicone resins include polydimethylsiloxane, polyphenylmethylsiloxane, polyalkylalkenylsiloxane, polyalkylhydrosiloxane, etc. Further, the silicone resin may be an addition cross-linked product of a silicone-based elastomer composition containing an organopolysiloxane having a hydrosilyl group (SiH group), an organopolysiloxane having a vinyl group, and an addition reaction catalyst, or may be an addition cross-linked product of a silicone rubber composition containing an organopolysiloxane having a vinyl group and an addition reaction catalyst. Furthermore, it may be a cross-linked product of a silicone-based elastomer composition containing an organopolysiloxane having a SiCH3 group and an organic peroxide curing agent, etc.

[0071] Examples of the addition reaction catalyst include metals, metal compounds, metal complexes, etc. having catalytic activity for hydrosilylation reaction, and specifically include platinum, platinum compounds, their complexes, etc. Examples of the organic peroxide curing agent include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, etc. Note that the elastic layer 11A may further contain components other than the silicone resin, such as an adhesion promoter, a silane coupling agent, a filler, etc., as necessary, together with the silicone resin.

[0072] On the other hand, the glass transition temperature of the resin constituting the heat-resistant resin layers 11B and 11C is preferably 150°C or higher, more preferably 150 to 500°C. The glass transition temperature is measured in accordance with JIS K 7095:2012. Examples of the resin constituting the heat-resistant resin layers 11B and 11C include engineering plastics such as polyamide, polycarbonate, polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, and polyetherimide; acrylic resin; urethane resin; epoxy resin; olefin resin, etc. The heat-resistant resin layers 11B and 11C may contain a plurality of these resins. Further, each of the heat-resistant resin layers 11B and 11C may further contain other components such as a filler as necessary together with the above resin.

[0073] On the other hand, the shape of the through hole 12 is not particularly limited, and for example, it can be columnar. The through hole 12 may be cylindrical, prismatic, or other shapes. The shape of the cross section orthogonal to the axial direction of the through hole 12 is, for example, circular, elliptical, quadrangular, or other polygons.

[0074] The through hole 12 may be a hole formed by any method, for example, a hole formed by mechanical processing (such as press working, punching), or a hole formed by laser processing such as femtosecond laser processing or CO2 laser processing.

[0075] Note that the thickness of the insulating layer 11 only needs to be able to insulate the substrate of the electrical inspection device and the object to be inspected, and is usually preferably 40 to 500 μm, more preferably 100 to 300 μm.

[0076] On the other hand, the conductive layer 13 is a layer formed on the inner wall surface 12c of the through hole 12 by electroless plating using the above-mentioned electroless plating solution. The conductive layer 13 of the unit surrounded by the broken line functions as one conductive path (see FIG. 1B). The volume resistivity of the conductive layer 13 (electroless plating layer) only needs to be such that sufficient conduction can be obtained and is not particularly limited. For example, 1.0×10×10-4 It is preferably below Ω·cm, and more preferably 1.0×10×10 -6 ~1.0×10 -9 Ω·cm. The volume resistivity of the conductive layer 13 can be measured by the method described in ASTM D 991.

[0077] The thickness of the conductive layer 13 is not particularly limited as long as sufficient electrical conductivity can be obtained. Usually, the thickness of the conductive layer 13 is preferably 0.1 to 5 μm. When the thickness of the conductive layer 13 is equal to or greater than a certain value, sufficient electrical conductivity is easily obtained. When it is equal to or less than a certain value, the through-hole 12 is less likely to be blocked, and the terminals of the object to be inspected are less likely to be damaged due to contact with the conductive layer 13. Note that the thickness of the conductive layer 13 is the thickness in the direction orthogonal to the thickness direction of the insulating layer.

[0078] In FIG. 1B, a mode in which the conductive layer 13 is formed only on the inner wall surface 12c of the through-hole 12 is shown, but the conductive layer 13 may also be formed on the first surface or the second surface of the insulating layer 11.

[0079] (Method for manufacturing an anisotropic conductive sheet) The anisotropic conductive sheet can be manufactured by a method similar to the method for manufacturing the above-described material to be plated. For example, the above-described insulating layer 11 (insulating sheet) is pretreated as necessary. Then, a conductive layer (electroless plating layer) can be formed on the inner wall surface 12c of the through-hole 12 of the insulating layer 11 (insulating sheet) using the above-described electroless plating solution.

Examples

[0080] Hereinafter, the present invention will be described with reference to examples. The scope of the present invention is not construed as being limited by the examples.

[0081] 1. Verification regarding the stability of the electroless plating solution As follows, electroless plating solutions of Example 1, Comparative Example 1, and Comparative Example 2 were prepared, and the increase rate of Fe 3+ ions was verified when these electroless plating solutions were left in the air.

[0082] [Preparation of Electroless Plating Solution] (1) Preparation of Electroless Plating Solution of Example 1 Sodium gluconate (monocarboxylic acid-based complexing agent), iron(II) sulfate heptahydrate (iron ion source), nickel(II) sulfate hexahydrate (nickel ion source), dimethylamine borane (DMAB, reducing agent), and tripotassium citrate (polycarboxylic acid-based complexing agent) were added to water so that the concentration of each component became the concentration shown in Table 1. At this time, it was adjusted with NaOH so that the pH became 10, and the electroless plating solution of Example 1 was obtained.

[0083] (2) Preparation of Electroless Plating Solution of Comparative Example 1 An electroless plating solution was obtained in the same manner as in Example 1, except that only sodium gluconate (monocarboxylic acid-based complexing agent) was used as the complexing agent and tripotassium citrate (polycarboxylic acid-based complexing agent) was not used.

[0084] (3) Preparation of Electroless Plating Solution of Comparative Example 2 An electroless plating solution was obtained in the same manner as in Example 1, except that only tripotassium citrate (polycarboxylic acid-based complexing agent) was used as the complexing agent and sodium gluconate (monocarboxylic acid-based complexing agent) was not used.

[0085] [Composition of Each Electroless Plating Solution]

Table 1

[0086] [Evaluation] (Measurement of Fe 3+ Ion Concentration) When the electroless plating solutions of Example 1, Comparative Example 1, and Comparative Example 2 were each left in the air, the amount of Fe 3+ ions in the electroless plating solution was measured with a spectroscopic apparatus. At this time, the relative value with respect to the amount of initial Fe 3+ ions was specified, and the increase rate of Fe 3+ ions was compared. The results are shown in Figure 2.

[0087] (Results) As shown in FIG. 2, in the electroless plating solution of Comparative Example 2 containing only tripotassium citrate (a polycarboxylic acid-based complexing agent) as a complexing agent, Fe was removed by leaving it for about 30 hours. 3+ The amount of ions doubled, and after 75 hours it tripled. These results suggest that in electroless plating solutions containing only tripotassium citrate as a complexing agent, iron deposition becomes more difficult over time and the solution is not stable enough.

[0088] In contrast, in the electroless plating solution of Comparative Example 1, which contained only sodium gluconate as a complexing agent, and the electroless plating solution of Example 1, which contained two types of carboxylic acid complexing agents (sodium gluconate and trisodium citrate), Fe remained even after 150 hours or more had elapsed. 3+ The amount of ions was less than twice the initial value and was very stable.

[0089] 2. Verification of iron content (eutectoid rate) in iron-nickel alloy coating The electroless plating solutions of Examples 2 to 5 were prepared as follows. The electroless plating solutions of Comparative Example 1 and Example 1 were also prepared. Iron-nickel alloy films were formed using these electroless plating solutions, and the iron content (mass %) in the films was evaluated.

[0090] [Preparation of electroless plating solution] The electroless plating solutions of Examples 2 to 5 were prepared in the same manner as in Example 1, except that the ratio of the monocarboxylic acid complexing agent (sodium gluconate) and the polycarboxylic acid complexing agent (trisodium citrate) was changed as shown in Table 2.

[0091] [Composition of each electroless plating solution] [Table 2]

[0092] [evaluation] (Formation of electroless plating layer) As a substrate, polyimide (manufactured by Toray DuPont Co., Ltd., Kapton (registered trademark) 30EN) was prepared. Then, the substrate was alkali-modified (immersed in a 2% sodium hydroxide solution at 50°C for 15 minutes) according to a conventional method, and immersed in a 2% sulfuric acid solution at room temperature for 5 minutes for neutralization. Further, it was immersed in a catalyst adsorption promoter (OPC Condiclean SCD manufactured by Okuno Pharmaceutical Co., Ltd.) at 50°C for 3 minutes. Furthermore, the substrate after contact with the catalyst adsorption promoter was immersed in a Pd catalyst solution at 40°C (Cataposit 44 manufactured by Rohm and Haas Electronic Materials Co., Ltd.) for 3 minutes. Then, it was immersed in a reducing agent (Accelerator 19E manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at 30°C for 3 minutes to activate Pd.

[0093] Subsequently, the above substrate was immersed in the electroless plating solutions of Comparative Example 1 and Examples 1 to 5 for 20 minutes to form an iron-nickel alloy film. Then, the substrate on which the iron-nickel alloy film was formed was annealed at 120°C for 30 minutes.

[0094] (Measurement of iron content (eutectoid ratio)) The iron content (eutectoid ratio) in the iron-nickel alloy film obtained by the above method was measured with a laser elemental analyzer (EA300 manufactured by Keyence Corporation). The iron content (eutectoid ratio) in the iron-nickel alloy films obtained from the electroless plating solutions of Comparative Example 1 and Examples 1 to 4 is shown in Figure 3.

[0095] (Results) As shown in Figure 3, in Comparative Example 1 that does not contain a polycarboxylic acid complexing agent, the iron content in the iron-nickel alloy film was less than 50% by mass. On the other hand, in Examples 1 to 4 in which a monocarboxylic acid complexing agent and a polycarboxylic acid complexing agent were used in combination, the iron content in the iron-nickel alloy film was all over 55% by mass. Also, in Example 5, the iron content in the film was 50% by mass. As described above, the electroless plating solution of Comparative Example 1 is the first iron ion (Fe 2+Although it has high stability, it can be said that iron is difficult to deposit sufficiently. On the other hand, according to the electroless plating solution using a monocarboxylic acid complexing agent and a polycarboxylic acid complexing agent in combination, iron can be deposited sufficiently, and its content rate can be made 50% by mass or more.

[0096] 3. Verification about the type of polycarboxylic acid complexing agent The electroless plating solutions of Example 6 and Comparative Example 3 were prepared as follows. Also, the plating solution of Example 1 described above was prepared. Then, using these electroless plating solutions, an iron-nickel alloy film was formed, and the stability of the electroless plating solution and the possibility of forming the iron-nickel alloy film were evaluated.

[0097] [Preparation of electroless plating solution] The electroless plating solutions of Example 6 and Comparative Example 4 were prepared in the same manner as in Example 1, except that the type of the polycarboxylic acid complexing agent was changed as shown in Table 3. Note that lactic acid is a compound that does not correspond to the polycarboxylic acid complexing agent of the present application.

[0098] [Composition and evaluation results of each electroless plating solution] Similar to the above, the stability of the electroless plating solution and the iron-nickel alloy film were evaluated according to the following criteria. The results are shown in Table 3.

[0099] (Stability of plating solution) ◎: Even after 24 hours, no turbidity or precipitate of the solution occurs. ○: After 24 hours, turbidity and precipitate of the solution occurred, but immediately after preparation, no turbidity and precipitate of the solution occurred. ×: Immediately after preparation, turbidity or precipitate of the solution occurred.

[0100] (Evaluation of iron-nickel alloy film) ○: There is no un-deposited part, and the ratio of iron is 50% by mass or more. ×: Plating is impossible, or even if plating is possible, there is an un-deposited part, or the ratio of iron is less than 50% by mass.

[0101]

Table 3

[0102] As shown in Table 3 above, in the electroless plating solution combining a monocarboxylic acid complexing agent (sodium gluconate) and a polycarboxylic acid complexing agent (tripotassium citrate or tartaric acid), the electroless plating solution was stable and capable of forming a desired iron-nickel alloy film (Examples 1 and 6).

[0103] On the other hand, when lactic acid was combined with sodium gluconate, precipitates were formed and electroless plating could not be performed (Comparative Example 4).

[0104] 4. Evaluation of Electroless Plating Solution Containing Modified Polyethyleneimine [Preparation of Electroless Plating Solution] To the electroless iron plating solution prepared in Example 1, polyethyleneimine ethoxylate (manufactured by Nippon Shokubai Co., Ltd.: PN-100) was further added to obtain the electroless plating solution of Example 7. The amount of polyethyleneimine ethoxylate was 300 mg / L.

[0105] [Evaluation] A polyimide sheet (manufactured by Toray DuPont Co., Ltd., Kapton (registered trademark) 30EN) was cut into a size of 5 cm × 5 cm, and electroless iron-nickel plating was performed using the electroless plating prepared in Example 7 and the electroless plating solution of Example 1 described above. Then, the composition of the obtained film was measured at 5 locations to evaluate the uniformity of the film composition. The minimum value and maximum value of the iron content rate at 5 locations and the average value of the iron content rate are shown in Table 4 below

[0106]

Table 4

[0107] [Results] As shown in Table 4 above, according to the electroless plating solution of Example 7 to which polyethyleneimine ethoxylate was added, a uniform iron-nickel alloy film with less variation in film composition could be formed compared to the electroless plating solution of Example 1 to which this was not added (Example 7).

Industrial Applicability

[0108] According to the electroless plating solution of the present invention, it is possible to stably form an iron-nickel alloy film with a high iron content. Therefore, it is very useful when manufacturing anisotropic conductive sheets and various products.

Explanation of Symbols

[0109] 10 Anisotropic conductive sheet 11 Insulating layer 11A Elastic layer 11B, 11C Heat-resistant resin layer 12 Through-hole 12c Inner wall surface 13 Conductive layer

Claims

1. An electroless iron-nickel plating solution containing an iron ion source, a nickel ion source, a reducing agent, and a complexing agent, wherein the complexing agent includes a monocarboxylic acid-based complexing agent containing a monocarboxylic acid or a salt thereof having one carboxy group and two or more hydroxy groups and having 2 or more carbon atoms, and a polycarboxylic acid-based complexing agent containing a polycarboxylic acid or a salt thereof having two or more carboxy groups and one or more hydroxy groups and having 2 or more carbon atoms, and includes an electroless iron-nickel plating solution.

2. The electroless iron-nickel plating solution according to claim 1, wherein the molar ratio of the content of iron element to the content of nickel element in the electroless iron-nickel plating solution is 2:3 to 1:

1. The electroless iron-nickel plating solution according to claim 1.

3. The electroless iron-nickel plating solution according to claim 1, wherein at least one of the monocarboxylic acid-based complexing agent and the polycarboxylic acid-based complexing agent is a sodium salt or a potassium salt. The electroless iron-nickel plating solution according to claim 1.

4. The electroless iron-nickel plating solution according to claim 1, wherein the total content of the monocarboxylic acid-based complexing agent and the polycarboxylic acid-based complexing agent is 200 mol% or more with respect to the total content of iron element and nickel element in the electroless iron-nickel plating solution. The electroless iron-nickel plating solution according to claim 1.

5. The electroless iron-nickel plating solution according to claim 4, wherein the molar ratio of the content of the monocarboxylic acid-based complexing agent to the content of the polycarboxylic acid-based complexing agent is 4:6 to 8:

2. The electroless iron-nickel plating solution according to claim 4.

6. The electroless iron-nickel plating solution according to claim 1, wherein the content of the monocarboxylic acid-based complexing agent is 200 mol% or more with respect to the content of iron element in the electroless iron-nickel plating solution. The electroless iron-nickel plating solution according to claim 1.

7. The monocarboxylic acid-based complexing agent includes at least one compound selected from the group consisting of gluconic acid, sodium gluconate, and potassium gluconate, and the polycarboxylic acid-based complexing agent includes at least one compound selected from the group consisting of citric acid, tartaric acid, and their sodium salts, potassium salts, and potassium sodium salts. The electroless iron-nickel plating solution according to claim 1.

8. further includes a modified polyethyleneimine having a number average molecular weight exceeding 1000 and less than 50000, wherein the modified polyethyleneimine includes ethyleneimine structural units, One or more alkylene oxide structures having 2 to 12 carbon atoms added to the nitrogen atom of the ethyleneimine structural unit, and / or a structure derived from octadecyl isocyanate added to the nitrogen atom of the ethyleneimine structural unit, The electroless iron-nickel plating solution according to claim 1.

9. The modified polyethyleneimine contains a structure represented by the following general formula (1a), The electroless iron-nickel plating solution according to claim 8. 【Chemical 1】 (In the general formula (1a), R １ represents an alkylene group having 2 to 12 carbon atoms, R ２ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, m and n satisfy 1000 < 100m + 50n < 50000)

10. The modified polyethyleneimine contains an ethylene oxide structure and / or a propylene oxide structure, The electroless iron-nickel plating solution according to claim 8.

11. A step of preparing a substrate, A step of forming an electroless plating layer on the substrate using the electroless iron-nickel plating solution according to any one of claims 1 to 10, A method for manufacturing a material to be plated, comprising:

12. An insulating layer having a first surface located on one side in the thickness direction, a second surface located on the other side in the thickness direction, and a plurality of through holes communicating the first surface and the second surface, A plurality of conductive layers disposed on at least the inner wall surfaces of the plurality of through holes, An anisotropic conductive sheet having: The conductive layer is an electroless plating layer containing iron and nickel, The content of iron in the electroless plating layer is 50% by mass or more, An anisotropic conductive sheet.

13. The insulating layer is a composite material having a heat-resistant resin portion containing a heat-resistant resin and an elastic portion having a lower elastic modulus than the heat-resistant resin portion, The anisotropic conductive sheet according to claim 12.

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