Electrolytic copper plating solution, method for manufacturing material to be plated and method for manufacturing anisotropic conductive sheet

Abstract

To provide an electrolytic copper plating solution capable of depositing a copper plating layer excellent in adhesion with various kinds of base materials without causing a film swell even by heating.SOLUTION: An electrolytic copper plating solution includes a copper ion source, a reducer, a complexing agent, modified polyethylene imine having a number average molecular weight of more than 2000 and less than 50000 and a thioether compound including an oxygen system functional group. The modified polyethylene imine includes: an ethyleneimine constitutional unit; one or more alkylene oxide structures added to the nitrogen atom of the ethyleneimine constitutional unit and having carbon atoms of 2 or more and 12 or less; and / or a structure derived from octadecyl isocyanate added to the nitrogen atom of the ethyleneimine constitutional unit.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electroless copper plating solution, a method for producing a plated material, and a method for producing an anisotropic conductive sheet. [Background technology]

[0002] Electroless copper plating is widely used in various fields, including, for example, in the field of semiconductor device manufacturing. A wide variety of electroless copper plating solutions are known for use in such electroless copper plating. Patent Document 1 describes electroless copper plating containing a stabilizer such as polyethyleneimine in addition to a copper ion source, a complexing agent, a reducing agent, etc. Patent Document 2 also describes the use of a tellurium compound as a deposition stabilizer for electroless copper plating solutions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7348984 [Patent Document 2] Patent No. 7111410 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, copper plating layers are sometimes exposed to high temperatures (for example, temperatures of 150°C or higher) when products containing the copper plating layers are used or during the manufacturing process of the products. However, plating layers obtained from conventional electroless copper plating solutions have the problem that they are prone to film blistering due to such heat, which can lead to performance degradation and poor appearance.

[0005] The present invention has been made in view of the above-mentioned problems, and specifically aims to provide an electroless copper plating solution that is capable of forming a copper plating layer that is resistant to film blistering even when heated and has good adhesion to various substrates, as well as a method for manufacturing a plated material using the same and a method for manufacturing an anisotropic conductive sheet. [Means for solving the problem]

[0006] The present invention provides the following electroless copper plating solution. [1] An electroless copper plating solution comprising: a copper ion source; a reducing agent; a complexing agent; a modified polyethyleneimine having a number-average molecular weight of more than 1,000 and less than 50,000; and a thioether compound containing an oxygen-based functional group, wherein the modified polyethyleneimine comprises an ethyleneimine structural unit; and one or more alkylene oxide structures having from 2 to 12 carbon atoms attached to a nitrogen atom of the ethyleneimine structural unit, and / or a structure derived from octadecyl isocyanate attached to a nitrogen atom of the ethyleneimine structural unit. [2] The electroless copper plating solution according to [1], wherein the modified polyethyleneimine contains a structure represented by the following general formula (1a): [ka] (In general formula (1a), R 1 represents an alkylene group having 2 to 12 carbon atoms, and R 2 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and m and n satisfy the condition 1000<100m+50n<50000. [3] The electroless copper plating solution according to [1] or [2], wherein the modified polyethyleneimine contains an ethylene oxide structure and / or a propylene oxide structure. [4] The electroless copper plating solution according to any one of [1] to [3], wherein the amount of the modified polyethyleneimine is from 2 to 100 times the amount of the thioether compound.

[0007] The present invention provides the following method for producing a plated material. [5] A method for producing a plated material, comprising the steps of: preparing a substrate; and forming a copper plating layer on the substrate using the electroless copper plating solution according to any one of [1] to [4]. [6] The method for producing a plated material according to [5], wherein the substrate contains at least one resin selected from the group consisting of polyimide, aromatic polyether ketone, epoxy resin, and polydimethylsiloxane.

[0008] The present invention provides the following method for producing an anisotropically conductive sheet. [7] A method for producing an anisotropically conductive sheet having 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 between the first surface and the second surface, and a plurality of conductive layers arranged on at least the inner wall surfaces of the plurality of through holes, the method comprising the step of forming the conductive layers on the insulating layer using the electroless copper plating solution according to any one of [1] to [4]. [8] A method for manufacturing an anisotropically conductive sheet according to [7], 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. [Effects of the Invention]

[0009] The electroless copper plating solution of the present invention makes it possible to form a copper plating layer that is resistant to film blistering even when heated and has good adhesion to various substrates. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1A is a plan view of an anisotropic conductive sheet according to one embodiment of the present invention, and FIG. 1B is an enlarged cross-sectional view taken along line 1B-1B in FIG. 1A. DETAILED DESCRIPTION OF THE INVENTION

[0011] The electroless copper plating solution, the method for producing a plated material, and the method for producing an anisotropic conductive sheet of the present invention will be described below using specific embodiments as examples, although the electroless copper plating solution, the method for producing a plated material, and the method for producing an anisotropic conductive sheet of the present invention are not limited to these embodiments.

[0012] 1. Electroless copper plating solution An electroless copper plating solution according to one embodiment of the present invention includes a copper ion source, a reducing agent, a complexing agent, a modified polyethyleneimine having a specific structure, and a thioether-based compound containing an oxygen-based functional group.

[0013] As mentioned above, plating layers obtained using conventional electroless copper plating solutions tend to blister when heated to high temperatures. The reasons for this are unclear, but the following is a possible explanation: When a plating layer is formed using a typical electroless copper plating solution, the crystal size of copper or its alloy in the resulting copper plating layer becomes relatively small. When the plating layer is heated, the crystals gradually grow and their size increases. This causes changes in the thermal expansion and contraction coefficients of the plating layer, making it more likely that peeling will occur between the substrate and the plating layer during heating or cooling. Furthermore, it is believed that the change in the crystal size of the substrate prevents the plating layer from returning to its original shape, resulting in blistering of the plating layer.

[0014] On the other hand, the electroless copper plating solution of the present application contains a specific modified polyethyleneimine and an ether-based compound containing an oxygen-based functional group. When a copper plating layer is formed using an electroless copper plating solution containing these, the crystal size of copper or its alloy in the copper plating layer becomes relatively large due to the interaction between the ether-based compound and the modified polyethyleneimine. Furthermore, if the crystal size is large from the beginning, the crystals are unlikely to grow even when heated, and the thermal expansion coefficient and thermal contraction coefficient of the plating layer are unlikely to change. Therefore, even when heated or cooled, the adhesion between the substrate and the plating layer is unlikely to change, and further, the plating layer returns to its original shape, which is thought to make the film less likely to blister.

[0015] Furthermore, electroless copper plating solutions containing specific modified polyethyleneimine and ether-based compounds containing oxygen-based functional groups make it possible to form copper plating layers on substrates on which it has been difficult to form copper plating layers in the past (e.g., substrates containing polyimide, aromatic polyether ketone, epoxy resin, polydimethylsiloxane, etc.). The reasons for this are unclear, but are thought to be as follows: Even when the above-mentioned resins are treated before plating, the surface roughening is minimal, and the irregularities formed on the surface are fine. In contrast, although the crystal diameters formed by the electroless copper plating solution of the present application are relatively large as described above, the particle diameter of the crystals initially formed is small. Therefore, the crystals can penetrate into the fine irregularities, and film growth can occur from these as starting points. As a result, it is thought that a nano-anchor effect adhesion was achieved.

[0016] The electroless copper plating solution of this embodiment may further contain components other than the copper ion source, reducing agent, complexing agent, specific modified polyethyleneimine, and specific thioether-based compound. Examples of such components include metal ion sources other than the copper ion source, solvents, pH adjusters, and other components. Each component in the electroless copper plating solution will be specifically described below.

[0017] (copper ion source) The copper ion source may be any compound that can dissolve in a solvent and supply copper ions. The electroless copper plating solution of the present embodiment may contain only one type of copper ion source, or may contain two or more types of copper ion sources.

[0018] Examples of copper ion sources include water-soluble copper salts such as copper sulfate, copper nitrate, copper chloride, copper acetate, copper citrate, copper tartrate, and copper gluconate, as well as hydrates thereof. Among these, copper sulfate pentahydrate and copper chloride are preferred from the viewpoints of availability and ease of handling.

[0019] The amount of copper ion source in the electroless copper plating solution is preferably an amount that results in an amount of elemental copper in the electroless copper plating solution of 0.01 mol / L to 0.5 mol / L, more preferably an amount that results in an amount of elemental copper in the electroless copper plating solution of 0.02 mol / L to 0.1 mol / L. When the amount of elemental copper in the electroless copper plating solution is within this range, the electroless copper plating solution tends to be stable, and the deposition rate during electroless copper plating tends to be stable.

[0020] (reducing agent) The reducing agent may be any compound capable of reducing copper ions during electroless copper plating. The electroless copper plating solution of the present embodiment may contain only one reducing agent or may contain two or more reducing agents.

[0021] Examples of the reducing agent include formaldehyde, dimethylamine borane (DMAB), glyoxylic acid, glyoxylates, pyrophosphorous acid, phosphinates, hypophosphates, borohydrides, hydrazides, and carbohydrates, etc. Among these, formaldehyde is preferred from the viewpoint of reducing properties, etc.

[0022] The amount (concentration) of the reducing agent in the electroless copper plating solution is appropriately selected depending on the type of 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 reducing agent concentration is within this range, the deposition rate during electroless copper plating tends to be more stable.

[0023] (complexing agent) The complexing agent may be any compound capable of forming a complex with copper ions. Examples of the complexing agent include aminocarboxylic acids, hydroxycarboxylic acids, and polycarboxylic acids. The electroless copper plating solution of this embodiment may contain only one type of complexing agent, or may contain two or more types of complexing agents.

[0024] Examples of the aminocarboxylic acid include ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, triethylenetetraminehexaacetic acid, ethylenediaminetetrapropionic acid, aminetriacetic acid, iminodiacetic acid, hydroxyethyliminodiacetic acid, iminodipropionic acid, 1,3-propylenediaminetetraacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, glycol ether diaminetetraacetic acid, m-phenylenediaminetetraacetic acid, diaminopropionic acid, glutamic acid, dicarboxymethylglutamic acid, ornithine, cysteine, S-carboxymethyl-L-cysteine, N,N-bis(2-hydroxyethyl)glutamic acid, (S,S)-ethylenediaminesuccinic acid, and salts thereof.

[0025] Examples of the hydroxycarboxylic acid include tartaric acid, gluconic acid, citric acid, malic acid, glucoheptonic acid, glycolic acid, lactic acid, trihydroxybutyric acid, ascorbic acid, isocitric acid, hydroxymalonic acid, glyceric acid, hydroxybutyric acid, leucine, citramalic acid, salicylic acid, and salts thereof.

[0026] Examples of polycarboxylic acids include succinic acid, glutaric acid, malonic acid, adipic acid, oxalic acid, maleic acid, citraconic acid, itaconic acid, mesaconic acid, and salts thereof.

[0027] Among these, Rochelle salt, which is a salt of tartaric acid, that is, potassium sodium tartrate, and ethylenediaminetetraacetic acid are preferred.

[0028] The amount (concentration) of the complexing agent in the electroless copper plating solution is appropriately selected depending on the type of complexing agent, but is preferably 10 g / L or more and 80 g / L or less, and more preferably 20 g / L or more and 60 g / L or less. When the concentration of the complexing agent is within this range, the stability of the electroless copper plating solution is improved and the copper deposition rate is likely to be stabilized.

[0029] (modified polyethyleneimine) The modified polyethyleneimine is a polymer containing an ethyleneimine structural unit having an ethylene group and an amino group, and one or more alkylene oxide structures having 2 to 12 carbon atoms attached to the nitrogen atom of the ethyleneimine structural unit, and / or a structure derived from octadecyl isocyanate attached to the nitrogen atom of the ethyleneimine structural unit. That is, it is a polymer containing a structural unit represented by the following general formula (1): [ka] In the above general formula (1), R represents one or more alkylene oxide structures having 2 to 12 carbon atoms, or structures derived from octadecyl isocyanate.

[0030] The modified polyethyleneimine may be, for example, a polymer obtained by addition polymerization of alkylene oxide or octadecyl isocyanate by a known method to a main chain of polyethyleneimine obtained by polymerizing ethyleneimine. Hereinafter, the structure will be described as an example, but the structure of the modified polyethyleneimine is not limited to this structure.

[0031] The polyethyleneimine that forms the main chain of the modified polyethyleneimine may be linear or may have a structure crosslinked by polymerization, i.e., branched. Furthermore, within the scope that does not impair the purpose and effect of this embodiment, it may contain a structural unit derived from a monomer other than ethyleneimine (e.g., propyleneimine, etc.). Furthermore, the polyethyleneimine may contain not only a tertiary amino group such as that contained in the structural unit represented by the general formula (1) above, but also a primary amino group or a secondary amino group.

[0032] 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). [ka] In the above general formula (1a), R1 represents an alkylene group having 2 to 12 carbon atoms. 1 Specific examples of R include linear or branched alkylenes such as ethylene, propylene, isobutylene, 1-butene, 2-butene, trimethylethylene, tetramethylene, tetramethylethylene, butadiene, and octylene. 1 is preferably an ethylene group or a propylene group. In other words, it is preferable that the polyethyleneimine contains either or both of an alkylene oxide structure and a propylene oxide structure.

[0033] In the above general formula (1a), R 2 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. Specific examples of alkyl groups having 1 to 12 carbon atoms include a methyl group, an ethyl group, and a propyl group. Among these, R 2 is preferably a hydrogen atom.

[0034] In the general formula (1a), m and n may satisfy the relationship 1000<100m+50n<50000.

[0035] When R in the above general formula (1) is an octadecyl isocyanate group, the modified polyethyleneimine contains a structure represented by the following general formula (1b). [ka] In the above general formula (1b), p is preferably 15 or more and 40 or less.

[0036] Regardless of the structure of R in general formula (1), the number-average molecular weight of the modified polyethyleneimine is preferably more than 1,000 and less than 50,000, and more preferably from 1,200 to 20,000. When the number-average molecular weight of the modified polyethyleneimine is within this range, the resulting plating layer is less likely to suffer from film blistering and the adhesion between the plating layer and the substrate is likely to be improved. The number-average molecular weight is a value measured by gel permeation chromatography (GPC) using pullulan as the standard substance.

[0037] The amount (concentration) of the modified polyethyleneimine in the electroless copper plating solution is preferably 0.02 g / L or more and 2.0 g / L or less, and more preferably 0.2 g / L or more and 1.5 g / L or less. When the concentration of the modified polyethyleneimine is within this range, the resulting plating layer is less likely to develop blistering, and the adhesion between the substrate and the plating layer is more likely to be improved. Furthermore, the amount (concentration) of the modified polyethyleneimine is preferably 2 to 100 times, more preferably 20 to 60 times, the amount (concentration) of the thioether compound described below. When these ratios are within this range, the resulting plating layer is even less likely to develop blistering.

[0038] (Thioether compounds) The thioether compound may be any compound having a thioether group (-S-) and an oxygen-containing functional group. In this specification, the oxygen-containing functional group refers to a hydroxy group, an ether group, and a carboxy group. When the thioether compound has the oxygen functional group, the thioether compound becomes more soluble in the solvent (e.g., water) used in electroless copper plating. The electroless copper plating solution may contain only one type of thioether compound, or two or more types.

[0039] Specific examples of thioether compounds include thiodiglycol, thiodiglycolic acid, dithioglycolic acid, thiodipropionic acid, thiodipropanol, thiodibutyric acid, bis(undecaethylene glycol) thioether, bis(dodecaethylene glycol) thioether, bis(pentadecaethylene glycol) thioether, bis(triethylene glycol) thioether, etc. Among these, thioglycolic acid and dithioglycolic acid are preferred from the viewpoints of ease of handling and suppression of blistering of the plating layer.

[0040] The amount (concentration) of the thioether compound in the electroless copper plating solution is preferably from 10 mg / L to 80 mg / L, more preferably from 15 mg / L to 30 mg / L. When the concentration of the thioether compound is within this range, the resulting plating layer is less likely to blister, and the adhesion between the substrate and the plating layer is likely to be good.

[0041] (Other ingredients) The electroless copper plating solution may further contain a metal ion source other than copper, a pH adjuster, a pH buffer, a stabilizer, and the like.

[0042] The electroless copper plating solution may further contain a metal ion source other than the copper ion source, provided that the objectives and effects of this embodiment are not impaired. The inclusion of another metal ion source allows the plating layer to be a layer composed of an alloy of copper and another metal (copper alloy), making it possible to adjust the physical properties of the plating layer according to the type and application of the plated material. However, the total amount of other metal elements contained in the other metal ion source is preferably 40% by mass or less, more preferably 5% by mass or more and 30% by mass or less, relative to the amount of copper element in the electroless copper plating solution. Examples of other metal elements include nickel, iron, cobalt, tin, molybdenum, etc. Metal ion sources include sulfides, nitrates, chlorides, etc. of these metal elements.

[0043] The pH adjuster may be any compound that does not impair the performance of the electroless copper plating solution, and examples thereof include sodium hydroxide, potassium hydroxide, etc. The electroless copper plating solution is preferably adjusted with a pH adjuster so that the pH is between 8 and 13. The electroless copper plating solution may contain only one pH adjuster, or may contain two or more pH adjusters.

[0044] The pH buffer may be any compound that does not impair the performance of the electroless copper plating solution, and examples thereof include sodium tetraborate, sodium carbonate, etc. The electroless copper plating solution may contain only one pH buffer, or may contain two or more pH buffers.

[0045] Further, examples of the stabilizer include bismuth, lead, antimony, vanadium, thiourea, sodium thiocyanate, sodium nitrobenzenesulfonate (MBS), 2-propyn-1-ol, etc. The electroless copper plating solution may contain only one type of stabilizer or may contain two or more types.

[0046] The electroless copper plating solution may further contain a reaction accelerator. Examples of the reaction accelerator include sulfobetaine compounds such as sulfoxypropylpyridinium betaine. The electroless copper plating solution may contain only one type of reaction accelerator, or two or more types.

[0047] The electroless copper plating solution may further contain a surfactant. Examples of the surfactant include anionic surfactants such as polyoxyethylene alkyl ether sulfate and polyoxyethylene alkyl sulfosuccinate. The electroless copper plating solution may contain only one surfactant or two or more surfactants.

[0048] The content of these components is appropriately selected depending on the purpose of their addition.

[0049] (solvent) Electroless copper plating usually further contains a solvent. The solvent is not particularly limited as long as it can dissolve the iron ion source, nickel ion source, reducing agent, complexing agent, compound represented by general formula (1), and other components. Examples of the solvent include water, ketones (e.g., acetone), and alcohols (e.g., methanol, ethanol, isopropanol).

[0050] (Method for preparing electroless copper plating solution) The method for preparing the electroless copper plating solution is not particularly limited, and the solution can be prepared, for example, by adding a copper ion source, a complexing agent, a reducing agent, a modified polyethyleneimine, a thioether-based compound, and other components to the solvent, followed by stirring, etc. It is preferable to mix the complexing agent with the copper ion source before mixing the reducing agent.

[0051] 2. Manufacturing method of plated material The method for producing a plated material using the above-mentioned electroless copper plating solution can be the same as a known method. For example, the plated material can be produced by carrying out a step of preparing a substrate (hereinafter also referred to as a "substrate preparation step") and a step of forming a copper plating layer (copper or copper alloy film) on the substrate using the above-mentioned electroless copper plating solution (hereinafter also referred to as an "electroless copper plating treatment step"). In this specification, the "plated material" refers to a member in which plating has been applied to part or all of the substrate, and the type of the plated material is not particularly limited. Each step in the method for manufacturing the plated material will be described below.

[0052] (1) Base material preparation process In the substrate preparation step, a substrate for plating is prepared. The shape of the substrate is not particularly limited, and may be, for example, a flat plate or film, or may have a three-dimensional shape. Furthermore, the material of the substrate is not particularly limited, and may be, for example, a resin, metal, or ceramic (e.g., glass). As described above, by using the electroless copper plating solution described above, it is possible to form a highly adhesive electroless copper plating layer even on substrates containing resins such as polyimide, aromatic polyether ketone, epoxy resin, and polydimethylsiloxane, on which plating layers have traditionally been difficult to form.

[0053] In the substrate preparation step, it is preferable to perform a known pretreatment before the electroless copper plating step. Pretreatments include cleaning (degreasing) with an alkaline treatment solution or the like, acid treatment with an acidic solution, treatment with a catalyst adsorption promoter (primer solution), catalyst application to the plating area using a catalyst application agent, and catalyst reduction using a catalyst reducing agent. Known alkaline solutions, acidic solutions, primer solutions, catalyst application agents, and catalyst reducing agents can all be used. Examples of catalysts applied by catalytic treatment agents include zero-valent metals, specific examples of which include Pd, Ag, Cu, Ni, Al, Fe, and Co.

[0054] Each treatment can be carried out by a known method. The pretreatment may be carried out on the entire surface of the substrate, or only on the area to be electroless copper plated.

[0055] (2) Electroless copper plating process In the electroless copper plating process, the desired region is electrolessly plated using the electroless copper plating solution described above. In this process, the region to be plated of the substrate is brought into contact with an electroless copper plating bath (electroless copper plating solution) consisting of the electroless solution described above, and copper is deposited on the surface of the region to be plated by a chemical reaction. The method of contacting the region to be plated with the electroless copper plating bath is not particularly limited; only the region to be plated may be brought into contact with the electroless copper plating bath, or the entire substrate may be immersed in the electroless copper plating bath. Note that when only a portion of the substrate is to be plated, a masking treatment may be performed by applying a resist or the like to prevent the electroless copper plating bath from adhering to portions other than the region to be plated. Furthermore, in this process, it is preferable to stir the electroless copper plating bath. Examples of stirring methods include circulating the solution using a pump, rocking the object to be plated, and paddle stirring.

[0056] The temperature of the electroless copper plating bath when the substrate is brought into contact with the electroless copper plating bath is preferably 25 to 70° C., more preferably 30 to 50° C. When the temperature of the electroless copper plating bath is 25° C. or higher, an electroless copper plating layer can be formed efficiently. On the other hand, when the temperature is 70° C. or lower, the substrate is less likely to be affected.

[0057] The contact time between the substrate and the electroless copper plating bath is preferably 3 to 45 minutes, more preferably 10 to 30 minutes. When the contact time with the electroless copper plating bath is 3 minutes or more, an electroless copper plating layer can be formed efficiently. On the other hand, when it is 45 minutes or less, it is less likely to affect the substrate. This makes it possible to obtain a substrate to be plated with a desired electroless copper plating layer formed in the plating area. After contact with the electroless copper plating bath, an annealing treatment or the like may be carried out as needed. The annealing treatment is preferably carried out by heating at about 100°C to 150°C, and the treatment time is preferably 5 to 30 minutes.

[0058] After the electroless copper plating, electroplating may be further carried out with nickel, lead, tin, silver, gold, or alloys thereof. Electroplating can be carried out by a known method.

[0059] 3. Use of plated material The above-described plated material can be used in various applications. The electroless copper plating layer obtained from the above-described electroless copper plating solution is less likely to blister even when heated. Furthermore, the electroless copper plating layer exhibits good adhesion to various substrates on which it has been difficult to form an electroless copper plating layer in the past. Therefore, the above-described plated material can also be used in applications requiring heat resistance.

[0060] As an example of the use of the plated material, an anisotropic conductive sheet and a method for producing the same will be described.

[0061] (anisotropic conductive sheet) An anisotropically conductive sheet as used herein refers to a sheet that is conductive in the thickness direction and insulating in the surface direction. Such an anisotropically conductive sheet can be used as a probe (contact) for electrical testing. FIG. 1A shows a plan view of an anisotropically conductive sheet 10 according to one embodiment of the present invention, and FIG. 1B shows a partially enlarged cross-sectional view taken along line 1B-1B in FIG. 1A. The anisotropically conductive sheet 10 includes 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 connecting the first surface 11a and the second surface 11b, and a conductive layer (electroless copper plating layer) 13 disposed on the inner wall surfaces 12c of the through holes 12.

[0062] The anisotropically conductive sheet 10 is placed between the substrate of the electrical testing device and the object under test to ensure electrical contact between the electrodes of the substrate and the terminals of the object under test. During electrical testing, a pressing load is applied to ensure electrical connection between the substrate of the electrical testing device and the object under test. Therefore, the insulating layer 11 of the anisotropically 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, as shown in FIG. 1B, may be composed of multiple layers. In the embodiment shown in FIG. 1B, two heat-resistant resin layers 11B and 11C, which have a higher elastic modulus than the elastic layer 11A and are heat-resistant, are arranged on both sides of the elastic layer 11A, which has a low elastic modulus.

[0063] The elastic layer 11A may be a layer containing, for example, a silicone resin. Examples of silicone resins include polydimethylsiloxane, polyphenylmethylsiloxane, polyalkylalkenylsiloxane, and polyalkylhydrosiloxane. The silicone resin may be an addition-crosslinked product of a silicone-based elastomer composition containing an organopolysiloxane having hydrosilyl groups (SiH groups), an organopolysiloxane having vinyl groups, and an addition reaction catalyst. Alternatively, the silicone resin may be an addition-crosslinked product of a silicone rubber composition containing an organopolysiloxane having vinyl groups and an addition reaction catalyst. Furthermore, the silicone resin may be a crosslinked product of a silicone-based elastomer composition containing an organopolysiloxane having SiCH groups and an organic peroxide curing agent.

[0064] Examples of the addition reaction catalyst include metals, metal compounds, metal complexes, etc. that have catalytic activity for hydrosilylation reactions, specifically platinum, platinum compounds, and complexes thereof. Examples of organic peroxide curing agents include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, etc. In addition to the silicone resin, the elastic layer 11A may further contain components other than the silicone resin, such as a tackifier, a silane coupling agent, or a filler, as needed.

[0065] 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; and olefin resin. The heat-resistant resin layers 11B and 11C may contain a plurality of these resins. Furthermore, the heat-resistant resin layers 11B and 11C may each further contain other components, such as a filler, in addition to the above resins, as needed.

[0066] On the other hand, the shape of the through hole 12 is not particularly limited and may be, for example, a columnar shape. The through hole 12 may be a cylindrical shape, a rectangular columnar shape, or other shapes. The shape of the cross section perpendicular to the axial direction of the through hole 12 may be, for example, a circle, an ellipse, a rectangle, or another polygon.

[0067] The through hole 12 may be a hole formed by any method, for example, a hole formed by mechanical processing (e.g., press processing, punch processing), or a hole formed by laser processing such as femtosecond laser processing or CO2 laser processing.

[0068] The thickness of insulating layer 11 may be any thickness as long as it is capable of insulating the substrate of the electrical inspection device from the object to be inspected, and is usually preferably 40 to 500 μm, more preferably 100 to 300 μm.

[0069] 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 copper plating using the electroless copper plating solution described above. A unit of the conductive layer 13 surrounded by a dashed line functions as one conductive path (see FIG. 1B). The volume resistivity of the conductive layer 13 (electroless copper plating layer) is not particularly limited as long as sufficient conductivity is obtained, but it may be, for example, 1.0×10×10 -4Ω·cm or less is preferable, and 1.0×10×10 -6 ~1.0×10 -9 The volume resistivity of the conductive layer 13 can be measured by the method described in ASTM D 991.

[0070] The thickness of the conductive layer 13 is not particularly limited as long as it is within a range in which sufficient conductivity is 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 a certain level or more, sufficient conductivity is easily obtained, and when the thickness is less than a certain level, the through-holes 12 are less likely to be blocked or the terminals of the test object are less likely to be damaged by contact with the conductive layer 13. The thickness of the conductive layer 13 is measured in a direction perpendicular to the thickness direction of the insulating layer.

[0071] Although Figure 1B shows an embodiment in which the conductive layer 13 is formed only on the inner wall surface 12c of the through hole 12, the conductive layer 13 may also be formed on the first surface and the second surface of the insulating layer 11.

[0072] (Method of manufacturing anisotropic conductive sheets) The anisotropic conductive sheet can be manufactured by the same method as the manufacturing method of the plated material described above. For example, the insulating layer 11 (insulating sheet) described above is pretreated as necessary. Then, the anisotropic conductive sheet can be manufactured by forming a conductive layer (electroless copper plating layer) on the inner wall surface 12c of the through hole 12 of the insulating layer 11 (insulating sheet) using the electroless copper plating solution described above. [Example]

[0073] The present invention will be described below with reference to examples, which should not be construed as limiting the scope of the present invention.

[0074] 1. Material Preparation In the examples and comparative examples, the following materials were used. (copper ion source) Copper sulfate pentahydrate Copper chloride

[0075] (reducing agent) Formaldehyde

[0076] (complexing agent) Rochelle salt Ethylenediaminetetraacetic acid

[0077] (pH adjuster) Sodium hydroxide

[0078] (modified polyethyleneimine) Polyethyleneimine ethoxylate (molecular weight 13,000, manufactured by Nippon Shokubai Co., Ltd.) Propylene oxide modified polyethyleneimine (molecular weight 1400, manufactured by Nippon Shokubai Co., Ltd.)

[0079] (Thioether compounds) Thioglycolic acid Thiodiglycolic acid

[0080] (others) Nickel sulfate hexahydrate Polyethyleneimine Polyethylene glycol

[0081] 2. Preparation of electroless copper plating solution and preparation of plated materials Each electroless copper plating solution was prepared by the following method.

[0082] [Example 1] Copper sulfate pentahydrate, formaldehyde, Rochelle salt, sodium hydroxide, polyethyleneimine ethoxylate, and thiodiglycolic acid were added to water so that the concentrations of each component were as shown in Table 1, thereby obtaining the electroless copper plating of Example 1.

[0083] [Examples 2 to 6 and Comparative Examples 1 to 5] An electroless copper plating solution was prepared in the same manner as in Example 1, except that the materials used and their concentrations were changed as shown in Table 1.

[0084] [Preparation of plated material] Using the electroless copper plating solutions prepared in the above Examples and Comparative Examples, copper plating layers were formed on the substrates shown below. PI-1 (Polyimide substrate, manufactured by Toyobo Co., Ltd., Xenomax) PI-2 (Polyimide substrate, Toray Industries, Kapton 200EN) PEEK (Victrex Japan, 1000-050G)

[0085] Specifically, each substrate was immersed in a sodium hydroxide solution (concentration 20 g / L, pH 13.4) at 50°C for 30 minutes according to a conventional method. Simultaneous immersion and ultrasonic treatment (40 kHz) were also performed. The substrate was then removed and immersed in sulfuric acid (concentrated sulfuric acid: 100 ml / L solution) for 1 minute. This time, ultrasonic treatment (40 kHz) was also performed. The substrate was then immersed in a catalyst adsorption promoter (OPC Condiclean SCD, manufactured by Okuno Pharmaceutical Industries, Ltd.) at 50°C for 3 minutes. After contact with the catalyst adsorption promoter, the substrate was then immersed in a Pd catalyst solution (Cataposit 44, manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at 40°C for 3 minutes. The Pd was then activated by immersion in a reducing agent (Accelerator 19E, manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at 30°C for 3 minutes.

[0086] The substrate was then immersed in the electroless copper plating solution of each of the examples and comparative examples for 30 minutes to form a copper plating layer, and the resulting plated material was then annealed at 120°C for 20 minutes. [evaluation] Each of the prepared plated materials was evaluated according to the following criteria.

[0087] (Appearance of plating layer after annealing) The plating layer after the annealing treatment was visually inspected for blistering, and evaluated according to the following evaluation criteria. ○: No blister in the plating layer ×: There is a bulge in the plating layer ××: No plating layer formed

[0088] (Appearance of plating layer after heating) The plated material was heated at 160°C for 1 hour. After heating, the plated layer of the plated material was visually inspected for any blistering in areas other than those caused by the annealing treatment, and evaluated according to the following criteria. ○: No blister in the plating layer ×: There is a bulge in the plating layer

[0089] (Tape peel test) After heating at 160°C for 1 hour, the plated material was subjected to a tape peeling test in accordance with JIS H8504 (1999), and was evaluated according to the following criteria. ○: No peeling occurred as a result of the tape peeling test ×: Peeling occurred as a result of the tape peeling test

[0090] [result] [Table 1]

[0091] As shown in Table 1 above, a plating layer could not be formed using an electroless copper plating solution containing polyethyleneimine and a thioether-based compound (thiodiglycolic acid) (Comparative Example 4). Furthermore, although a plating layer could be formed using an electroless copper plating solution containing polyethylene glycol and a thioether-based compound, the results were poor in appearance and adhesion (Comparative Example 5). On the other hand, in Comparative Example 1, which did not contain modified polyethyleneimine or a thioether-based compound, a plating layer could be formed, but the appearance evaluation after heating was poor, and the adhesion of the plating layer was also poor (Comparative Example 1). Furthermore, even if modified polyethyleneimine was contained, the adhesion of the plating layer was poor when the thioether-based compound was not contained (Comparative Example 2). Furthermore, similar results were obtained when a thioether-based compound was contained but the modified polyethyleneimine was not contained (Comparative Example 3).

[0092] In contrast, the electroless copper plating solutions of Examples 1 to 6 containing modified polyethyleneimine and a thioether compound were able to form plating layers on all substrates. Furthermore, the plating layers did not blister even when heated, and the adhesion between each plating layer and the substrate was high.

[0093] [Examples 7 to 14] An electroless copper plating solution was prepared in the same manner as in Example 1, except that the materials used and their concentrations were changed as shown in Table 2. Then, a plated material was prepared in the same manner as in Example 1.

[0094] [Example 15] An electroless copper plating solution was prepared in the same manner as in Example 9, except that plasma treatment (power output 100W, treatment for 1 minute) was carried out after immersion in sulfuric acid. Then, a plated material was produced in the same manner as in Example 1.

[0095] [evaluation] The appearance of the plating layer after annealing and heating was evaluated, and a tape peeling test was carried out in the same manner as in Example 1. The results are shown in Table 2.

[0096] [result] [Table 2]

[0097] As shown in Table 2, it was possible to form a plating layer using any of the above electroless copper plating solutions. Furthermore, even when heated, the plating layer did not blister, and the adhesion between each plating layer and the substrate was high (Examples 7 to 15). [Industrial Applicability]

[0098] The electroless copper plating solution of the present invention is capable of forming a copper plating layer that is resistant to film blistering even when heated and has good adhesion to various substrates, and is therefore extremely useful in producing anisotropically conductive sheets and various other products. [Explanation of symbols]

[0099] 10 Anisotropic conductive sheet 11 Insulating layer 11A Elastic layer 11B, 11C Heat-resistant resin layer 12 Through holes 12c Inner wall 13 Conductive layer

Claims

1. a source of copper ions; A reducing agent; a complexing agent; and A modified polyethyleneimine having a number average molecular weight of more than 1,000 and less than 50,000; a thioether-based compound containing an oxygen-based functional group; Including, The modified polyethyleneimine is an ethyleneimine building block; one or more alkylene oxide structures having 2 to 12 carbon atoms attached to a nitrogen atom of the ethyleneimine structural unit, and / or a structure derived from octadecyl isocyanate attached to a nitrogen atom of the ethyleneimine structural unit, Electroless copper plating solution.

2. The modified polyethyleneimine comprises a structure represented by the following general formula (1a): The electroless copper plating solution according to claim 1. 【Chemical 1】 (In 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 the condition 1000<100m+50n<50000)

3. The modified polyethyleneimine contains an ethylene oxide structure and / or a propylene oxide structure. The electroless copper plating solution according to claim 1.

4. the amount of the modified polyethyleneimine is 2 to 100 times the amount of the thioether compound; The electroless copper plating solution according to claim 1.

5. providing a substrate; forming a copper plating layer on the substrate using the electroless copper plating solution according to any one of claims 1 to 4; A method for manufacturing a plated material, comprising:

6. the substrate contains at least one resin selected from the group consisting of polyimide, aromatic polyether ketone, epoxy resin, and polydimethylsiloxane; The method for manufacturing a plated material according to claim 5 .

7. an insulating layer having a first surface located on one side in a thickness direction, a second surface located on the other side in the thickness direction, and a plurality of through holes communicating between the first surface and the second surface; a plurality of conductive layers disposed on inner wall surfaces of at least the plurality of through holes; A method for producing an anisotropic conductive sheet comprising: forming the conductive layer on an insulating layer using the electroless copper plating solution according to any one of claims 1 to 4; A method for manufacturing an anisotropic conductive sheet.

8. 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. A method for producing the anisotropically conductive sheet according to claim 7.

Images