Copper plating solution for PR pulse electrolysis and copper plating method using PR pulse electrolysis

Abstract

The object of the present invention is to provide a novel copper plating solution for PR pulse electrolysis and a copper plating method using PR pulse electrolysis. The copper plating solution for PR pulse electrolysis contains copper (II) ions, multivalent metal ions (but not copper (II) ions) and unsaturated fatty acids.

Description

Technical Field

[0001] The invention relates to a copper plating solution for PR pulse electrolysis and a copper plating method utilizing the PR pulse electrolysis method. Background Art

[0002] Patent document 1 is a technology disclosed by the applicant, which discloses (1) an additive for a copper plating solution used in a PR pulse electrolysis method, comprising at least one component selected from olefins; (2) an acidic copper plating solution for electroplating using the PR pulse electrolysis method, which uses an acidic aqueous solution containing copper ions and at least one acid component selected from organic acids and inorganic acids as a basic plating bath and contains the above-mentioned additive; (3) a copper plating method using the PR pulse electrolysis method, in which a PR pulse current is passed through the above-mentioned acidic copper plating solution with an object to be plated as a cathode to perform electrolytic copper plating.

[0003] When copper plating is performed by PR pulse electrolysis using an electrolytic copper plating solution containing an additive of the technology disclosed by the present applicant, the advantages of the PR electrolytic copper plating solution such as good uniform electrochemical deposition can be maintained, and the appearance, film properties, and filling properties of the formed plated film can be improved. Moreover, the PR electrolytic copper plating solution containing the additive is particularly useful when performing via filling, through hole filling, through hole plating, etc. by electrolytic copper plating.

[0004] Patent document 2 discloses (1) an additive for a pulse copper plating bath containing a tertiary amine compound as an effective ingredient, wherein the tertiary amine compound is obtained by reacting epihalohydrin with a polyol to perform epoxidation, and then reacting the tertiary amine compound with an amine, wherein the polyol is selected from polyether polyols or polyalkylene glycols obtained by adding an alkylene oxide to a polyol having hydroxyl groups on adjacent carbon atoms; and (2) an additive for a pulse copper plating bath containing a quaternary ammonium compound as an effective ingredient, wherein the quaternary ammonium compound is obtained by reacting epihalohydrin with a polyol to perform epoxidation, and then reacting the tertiary amine compound with an amine, and then reacting the tertiary amine compound with a compound, wherein the polyol is selected from polyether polyols or polyalkylene glycols obtained by adding an alkylene oxide to a polyol having hydroxyl groups on adjacent carbon atoms.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5636633

[0008] Patent Document 2: Japanese Patent Application Publication No. 2008-266722 Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] The object of the present invention is to provide a novel copper plating solution for PR pulse electrolysis and a copper plating method using PR pulse electrolysis.

[0011] Technical solutions for solving technical problems

[0012] The inventors of the present invention have conducted intensive research and developed a technology for forming a copper film by pulse electrolysis using a copper (II) ion aqueous solution using copper sulfate or the like, using a combination of polyvalent metal ions such as iron (II) ions and unsaturated fatty acids.

[0013] That is, the present invention includes the following PR (Periodic Reverse) pulse electrolysis copper plating solution and PR pulse electrolysis copper plating method.

[0014] Item 1. A copper plating solution for PR pulse electrolysis, comprising copper (II) ions, polyvalent metal ions (but excluding copper (II) ions) and unsaturated fatty acids.

[0015] Item 2. The copper plating solution for PR pulse electrolysis according to Item 1 above, wherein the polyvalent metal ions are ions of at least one polyvalent metal selected from the group consisting of cobalt, iron, and cerium.

[0016] Item 3. The copper plating solution for PR pulse electrolysis as described in Item 1 or 2 above, wherein the polyvalent metal ion is at least one polyvalent metal ion selected from the group consisting of cobalt (II), iron (II) and cerium (III).

[0017] Item 4. The PR pulse electrolysis copper plating solution according to any one of Items 1 to 3, wherein the PR pulse electrolysis copper plating solution contains 0.3 g / L to 3.0 g / L of the polyvalent metal ion.

[0018] Item 5. The copper plating solution for PR pulse electrolysis according to any one of Items 1 to 4, wherein the unsaturated fatty acid is at least one unsaturated fatty acid selected from olefins and alkynes.

[0019] Item 6. The PR pulse electrolysis copper plating solution according to any one of Items 1 to 5, wherein the unsaturated fatty acid is at least one unsaturated fatty acid selected from olefins and alkynes having two or three carboxyl groups.

[0020] Item 7. The PR pulse electrolysis copper plating solution according to any one of Items 1 to 6, wherein the PR pulse electrolysis copper plating solution contains 0.5 g / L to 10 g / L of the unsaturated fatty acid.

[0021] Item 8. The copper plating solution for PR pulse electrolysis according to any one of Items 1 to 7, further comprising an acid component, wherein the copper plating solution for PR pulse electrolysis is an acidic aqueous solution.

[0022] Item 9. The copper plating solution for PR pulse electrolysis according to any one of Items 1 to 8, further comprising halide ions.

[0023] Item 10. The copper plating solution for PR pulse electrolysis according to any one of Items 1 to 9, further comprising a sulfur-containing organic compound.

[0024] Item 11. The PR pulse electrolysis copper plating solution according to any one of Items 1 to 10, wherein the total content of at least one amine compound selected from tertiary amine compounds and quaternary ammonium compounds in the PR pulse electrolysis copper plating solution is less than 1 mg / L.

[0025] Item 12. A copper plating method using PR pulse electrolysis, comprising: (1) in a PR pulse electrolysis copper plating solution, with the object to be plated as the cathode, passing a PR pulse current to carry out electrolytic copper plating, wherein the PR pulse electrolysis copper plating solution contains copper (II) ions, polyvalent metal ions (but not including copper (II) ions) and unsaturated fatty acids.

[0026] Item 13. A copper plating method utilizing PR pulse electrolysis as described in Item 12 above, wherein the above step (1) is carried out under PR pulse electrolysis conditions with an anode / cathode current density ratio (anode current density / cathode current density) of 0.2 to 0.85.

[0027] Item 14. A copper plating method utilizing PR pulse electrolysis as described in Item 12 or 13 above, wherein the above step (1) is carried out under PR pulse electrolysis conditions in which the positive current application time is set to 5 milliseconds to 200 milliseconds and the positive current / negative current application time ratio (positive current application time / negative current application time) is greater than 5 and less than 50.

[0028] In the prior art, when plating is performed on a substrate having densely distributed through holes and vias, the surface area per unit area varies greatly, so the surface film thickness after the plating becomes uneven.

[0029] The PR pulse electrolysis copper plating solution of the present invention uses multivalent metal ions such as iron (II) ions and unsaturated fatty acids, and contains copper (II) ions such as copper sulfate aqueous solution. By using the PR pulse electrolysis copper plating solution of the present invention, it is possible to generate a copper coating with a uniform surface film thickness by pulse electrolysis. By using the PR pulse electrolysis copper plating solution of the present invention, the surface film thickness of the copper coating can be uniformly distributed.

[0030] The copper plating solution for PR pulse electrolysis of the present invention preferably does not contain a tertiary amine compound and a quaternary ammonium compound.

[0031] Effects of the Invention

[0032] The present invention can provide a novel copper plating solution for PR pulse electrolysis and a copper plating method using PR pulse electrolysis. DETAILED DESCRIPTION

[0033] The present invention is described in detail below.

[0034] The embodiments of the present invention are provided for better understanding of the gist of the invention and do not limit the content of the invention unless otherwise specified.

[0035] In the present specification, “include” and “contain” include any concepts of “comprise”, “consist essentially of”, and “consist of”.

[0036] In this specification, when "A to B" is used to express a numerical range, it means that A is greater than or equal to B.

[0037] [1] PR Pulse Electrolytic Copper Plating Solution

[0038] The copper plating solution for PR pulse electrolysis of the present invention contains copper (II) ions, multivalent metal ions (but not including copper (II) ions) and unsaturated fatty acids.

[0039] The PR pulse electrolysis copper plating solution of the present invention uses multivalent metal ions such as iron (II) ions and unsaturated fatty acids, and contains copper (II) ions such as copper sulfate aqueous solution. By using the PR pulse electrolysis copper plating solution of the present invention, it is possible to generate a copper coating with a uniform surface film thickness by pulse electrolysis. By using the PR pulse electrolysis copper plating solution of the present invention, the surface film thickness of the copper coating can be uniformly distributed.

[0040] By using the PR pulse electrolytic copper plating solution of the present invention, when electrolytic copper plating is performed using the PR pulse electrolysis method, the formed plating film has a good appearance, good physical properties of the plated film, and good via filling properties, through-hole filling properties, etc. The PR pulse electrolytic copper plating method of the present invention can be effectively used as a plating method for via filling, through-hole filling, through-hole plating, etc.

[0041] In the conventional copper plating solution used for direct current electrolysis, if a copper plating solution containing a polymer, a sulfur additive (brightener), a tertiary amine compound, or a quaternary ammonium compound (leveling agent) as an additive is used, the uniformity of the film thickness is poor.

[0042] In the copper plating solution used when the current condition is a PR pulse, if a copper plating solution containing a polymer, a sulfur additive (brightener), a tertiary amine compound, or a quaternary ammonium compound (leveling agent) as an additive is used, the uniformity of the film thickness is insufficient and the coating properties are not good.

[0043] In the copper plating solution used when the existing current condition is a PR pulse, if a copper plating solution containing polyvalent metal ions, unsaturated fatty acids, polymers, sulfur additives (brighteners), tertiary amine compounds, and quaternary ammonium compounds (leveling agents) as additives is used, when the content of the tertiary amine compounds and quaternary ammonium compounds (leveling agents) is more than 1 mg / L, the uniformity of the film thickness is insufficient and the coating properties are not good.

[0044] In the copper plating solution used when the current condition of the present invention is a PR pulse, if a copper plating solution containing polyvalent metal ions, unsaturated fatty acids, polymers, and optional sulfur additives (brighteners) as additives is used, the uniformity of the film thickness is good and the coating properties are also good.

[0045] In the copper plating solution used when the current condition of the present invention is a PR pulse, if a copper plating solution containing polyvalent metal ions, unsaturated fatty acids, polymers, and optional sulfur-based additives (brighteners) as additives is used, the content of tertiary amine compounds and quaternary ammonium compounds (leveling agents) is preferably less than 1 mg / L, then the uniformity of the film thickness is good and the coating properties are also good.

[0046] [1-1] Copper (II) ion

[0047] The copper plating solution for PR pulse electrolysis of the present invention contains copper (II) ions.

[0048] The copper ion (II) source can be used without particular limitation as long as it is a copper compound soluble in the plating solution. The copper compound providing the copper ion (II) source is preferably copper (II) sulfate, copper (II) oxide, copper (II) chloride, copper (II) carbonate, copper (II) pyrophosphate, copper (II) alkanesulfonates such as copper (II) methanesulfonate, copper (II) alkanesulfonates such as copper (II) propanolsulfonate, copper (II) octoate, copper (II) laurate, copper (II) stearate, organic acid copper (II) such as copper (II) naphthenate, etc.

[0049] As the copper (II) ion source and the copper compound, at least one compound selected from the above compounds may be used. These copper (II) ion sources and copper compounds may be used alone or in combination of two or more.

[0050] The copper (II) ion concentration in the PR pulse electrolytic copper plating solution is not particularly limited and can be in any range. The copper (II) ion concentration in the PR pulse electrolytic copper plating solution is preferably in the range of 10 g / L to 300 g / L.

[0051] [1-2] Polyvalent metal ions (but not including copper (II) ions)

[0052] The PR pulse electrolysis copper plating solution of the present invention contains polyvalent metal ions. In the PR pulse electrolysis copper plating solution, the polyvalent metal ions are polyvalent metal ions that do not include copper (II) ions. In the PR pulse electrolysis copper plating solution, the polyvalent metal ions function as a film thickness leveling agent, which can improve the uniformity of the film thickness.

[0053] The polyvalent metal compound providing a source of polyvalent metal ions is preferably a sulfate or nitrate of cobalt, iron, cerium or the like.

[0054] The polyvalent metal ion is preferably an ion of at least one polyvalent metal selected from the group consisting of cobalt, iron and cerium. The polyvalent metal ion is more preferably an ion of at least one polyvalent metal selected from the group consisting of cobalt (II), iron (II) and cerium (III).

[0055] As the polyvalent metal ion source and the polyvalent metal, at least one compound selected from the above compounds may be used. These polyvalent metal ion sources and polyvalent metals may be used alone or in combination of two or more.

[0056] The polyvalent metal ion concentration in the PR pulse electrolysis copper plating solution is not particularly limited and can be set in any range. The polyvalent metal ion concentration in the PR pulse electrolysis copper plating solution is preferably set in the range of 0.3 g / L to 3.0 g / L.

[0057] Combination of polyvalent metal ions such as iron (II) ions and unsaturated fatty acids

[0058] Through holes (hereinafter also referred to as "TH") are formed in electronic components of printed circuit boards and IC substrates to impart thermal conductivity and heat conductivity. This structure in electronic components is developing towards miniaturization, and in copper electroplating, the TH (hole) is also developing towards smaller diameters and denser density. Electronic components are developing towards multi-layer lamination, and the board thickness is increasing, which means that the aspect ratio of the hole diameter to the board thickness is increasing. For substrates with a high aspect ratio, if there are a large number of "dense areas" and "non-dense areas" with holes, there will be differences in surface area even within the substrate.

[0059] The surface area of ​​the "non-dense part" (hereinafter also referred to as "TH sparse part") of the through hole (TH) is small, so electricity is relatively easy to flow. However, the surface area of ​​the "dense part" (hereinafter also referred to as "TH dense part") of the through hole (TH) is large, so it becomes a resistor and it is difficult for the current to flow. In the case of the method of applying a direct current for treatment, a large amount of current flows in the sparse part of the TH, so the copper deposition on the surface of the substrate is thicker. On the other hand, the current is difficult to flow in the dense part of the TH, so the copper deposition on the surface of the substrate is thinner.

[0060] Technology to make copper film thickness uniform

[0061] Normally, in order to prevent current distribution caused by surface area differences in printed circuit boards, nitrogen compounds that inhibit copper electrodeposition are used in PR pulse electrolytic copper plating solutions. Nitrogen compounds are usually composed of tertiary amine compounds and quaternary ammonium compounds, which carry a positive charge in aqueous solution. If a negative current is applied to the substrate, the tertiary amine compounds and quaternary ammonium compounds will be adsorbed on the substrate due to their positive charge, becoming resistors and inhibiting copper electrodeposition.

[0062] If the substrate is processed under high resistance as a whole, even if there is a surface area difference, the current distribution can be made uniform, and the film can be formed with a uniform film thickness distribution. However, if the ratio of the number of THs per unit area of ​​the sparse TH portion to the dense TH portion is more than 4, the uniformity of the surface film thickness of the copper is limited. If the surface film thickness of the copper of the printed circuit board is large, it is difficult to form a fine circuit. In addition, if the copper film thickness in the TH is too thin, the connection reliability deteriorates.

[0063] The TH dense part is difficult to flow current, resulting in thinner surface film thickness and film thickness in the through hole. In order to obtain connection reliability, it is necessary to adjust the plating treatment time and current to achieve a film thickness above the specified value. However, in the TH sparse part where current flows easily in the same substrate, the surface film thickness of copper will increase. The copper coating in the through hole also increases, and the pore size becomes too small, so that in the subsequent process of substrate manufacturing, residual residue of the processing liquid will be left, causing adverse conditions.

[0064] When via holes are present in the TH sparse portion, the portion becomes convex due to excessive filling of copper. Once the portion becomes convex, additional grinding or etching steps are required to adjust the surface shape, which causes problems in terms of economy and process.

[0065] Usefulness of the copper plating method using PR pulse electrolysis of the present invention

[0066] PR pulse electrolysis combines "positive pulse electrolysis for copper electrodeposition" and "negative pulse electrolysis for copper dissolution" to cycle positive and negative in a very short time. PR pulse electrolysis is an effective method for filling vias and through-holes with copper in a plating bath as a method for improving deposition efficiency.

[0067] The copper plating solution for PR pulse electrolysis of the present invention contains polyvalent metal ions, and copper is difficult to dissolve due to sacrificial oxidation during negative pulses. It preferably contains at least one unsaturated fatty acid selected from olefins and alkynes having at least two carboxyl groups, and at least one unsaturated fatty acid selected from olefins and alkynes having less than four carboxyl groups, thereby improving the copper precipitation efficiency.

[0068] Polyvalent metal ions and unsaturated fatty acids can exert their effects when low current is applied.

[0069] The reason for this is that in the TH dense portion, sacrificial oxidation of polyvalent metal ions is effective and the dissolution current is moderately suppressed, thereby reducing the dissolution of copper. At the time of a low positive pulse, unsaturated fatty acids can improve the copper precipitation efficiency.

[0070] On the other hand, since a high pulse current is applied to the TH sparse part, the effect of the polyvalent metal ions and unsaturated fatty acids is not easy to appear, and dissolution and precipitation occur repeatedly, gradually forming a copper film. As a result, the copper film thickness on the substrate surface of the TH dense part and the TH sparse part becomes uniform, and the through-hole copper coating of the TH dense part can also be processed with a film thickness that does not impair the connection reliability. In the TH sparse part, as long as excessive current treatment is not performed, it can be processed without increasing the copper coating of TH.

[0071] [1-3] Unsaturated fatty acids

[0072] The copper plating solution for PR pulse electrolysis of the present invention contains unsaturated fatty acid. In the copper plating solution for PR pulse electrolysis, the unsaturated fatty acid functions as an appearance enhancer and can improve the coating properties.

[0073] The unsaturated fatty acid is preferably at least one unsaturated fatty acid selected from olefins and alkynes. The unsaturated fatty acid is more preferably at least one unsaturated fatty acid selected from olefins and alkynes having two or three carboxyl groups. The unsaturated fatty acid is more preferably fumaric acid, maleic acid, acetylenedicarboxylic acid, aconitic acid, etc.

[0074] As the unsaturated fatty acid, at least one compound selected from the above compounds can be used. These unsaturated fatty acids may be used alone or in combination of two or more.

[0075] The unsaturated fatty acid content in the PR pulse electrolysis copper plating solution is not particularly limited and can be set in any range. The unsaturated fatty acid content in the PR pulse electrolysis copper plating solution is preferably set in the range of 0.5 g / L to 10 g / L.

[0076] [1-4] Acid components

[0077] The copper plating solution for PR pulse electrolysis of the present invention preferably further contains an acid component and is an acidic aqueous solution.

[0078] The acid component is preferably at least one acid component selected from an organic acid and an inorganic acid, so that the copper plating solution for PR pulse electrolysis can be an acidic copper plating solution.

[0079] The organic acid is preferably an alkanesulfonic acid such as methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, and 2-propanesulfonic acid; an alkanolsulfonic acid such as 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 1-hydroxypropane-2-sulfonic acid, and 3-hydroxypropane-1-sulfonic acid.

[0080] The inorganic acid is preferably sulfuric acid, hydrochloric acid or the like.

[0081] As the acid component, at least one compound selected from the above-mentioned compounds can be used. These acid components may be used alone or in combination of two or more.

[0082] The acid content in the copper plating solution for PR pulse electrolysis is not particularly limited and can be in any range. The acid content in the copper plating solution for PR pulse electrolysis is preferably in the range of 20 g / L to 300 g / L.

[0083] [1-5] Halide ions

[0084] The copper plating solution for PR pulse electrolysis of the present invention preferably further contains halide ions.

[0085] The halide ion is preferably a chloride ion (Cl - ), bromide ion (Br - )wait.

[0086] As the halide ion, at least one compound selected from the above-mentioned compounds may be used. These halide ions may be used alone or in combination of two or more.

[0087] The halide ion content in the PR pulse electrolysis copper plating solution is not particularly limited and can be set to any range. The halide ion content in the PR pulse electrolysis copper plating solution is preferably set to a range of 5 mg / L to 200 mg / L. The halide ion content can be adjusted as needed using hydrochloric acid, sodium chloride, etc. to adjust the halide ion concentration in the PR pulse electrolysis copper plating solution.

[0088] [1-6] Sulfur-containing organic compounds

[0089] The copper plating solution for PR pulse electrolysis of the present invention preferably further contains a sulfur-containing organic compound.

[0090] Sulfur-containing organic compounds are called brighteners. Sulfur-containing organic compounds are preferably used as additives added to copper sulfate plating solutions for through-hole plating or as additives added to copper sulfate plating for blind-hole vias.

[0091] As the sulfur-containing organic compound, preferably used is a sulfur compound such as 3-mercaptopropanesulfonic acid, its sodium salt, bis(3-sulfopropyl)disulfide, its disodium salt, N,N-dimethyldithiocarbamic acid (3-sulfopropyl) ester, its sodium salt or the like.

[0092] As the sulfur-containing organic compound, at least one compound selected from the above-mentioned compounds may be used. These sulfur-containing organic compounds may be used alone or in combination of two or more thereof.

[0093] The content of the sulfur-containing organic compound in the PR pulse electrolytic copper plating solution is not particularly limited and can be set in any range. The content of the sulfur-containing organic compound in the PR pulse electrolytic copper plating solution is preferably set in the range of 0.1 mg / L to 50 mg / L.

[0094] [1-7] Tertiary amine compounds and quaternary ammonium compounds

[0095] In the PR pulse electrolytic copper plating solution of the present invention, the total content of at least one amine compound (nitrogen-based compound) selected from tertiary amine compounds and quaternary ammonium compounds in the PR pulse electrolytic copper plating solution is preferably less than 1 mg / L.

[0096] Technology to reduce the concentration of nitrogen compounds

[0097] If the copper plating solution for PR pulse electrolysis contains a large amount of tertiary amine compounds and quaternary ammonium compounds, the electrodeposition of copper will be inhibited, so it is difficult to obtain the effects of polyvalent metal ions and unsaturated fatty acids. The content of tertiary amine compounds and quaternary ammonium compounds is preferably less than 1 mg / L, or is not contained.

[0098] Pulse electrolysis not only dissolves copper during negative pulses, but also removes sulfur-based additives that are a factor in improving the physical properties of the coating. If the copper surface does not adsorb sulfur-based additives but adsorbs nitrogen-based compounds to produce a coating, the ductility of the coating will deteriorate.

[0099] The thermal expansion coefficients of the epoxy resin and copper used in the substrate are very different. Therefore, once a copper-plated film with poor ductility is formed, when the substrate undergoes thermal expansion, it cannot follow the expansion of the resin, thus causing cracks in the copper-plated film and causing power outages.

[0100] The PR pulse electrolytic copper plating solution of the present invention preferably does not require a large amount of nitrogen compounds commonly used in acidic copper sulfate plating solutions. Therefore, although PR pulse electrolysis treatment is used, concerns about the physical properties of the coating are systematically eliminated, and a copper coating with good physical properties can be obtained.

[0101] The nitrogen-containing organic compound is generally called a leveling agent. The tertiary amine compound and the quaternary ammonium compound are preferably used as an additive blended in a copper sulfate plating solution for through-hole plating or an additive blended in a copper sulfate plating solution for blind-hole vias.

[0102] As the tertiary amine compound and the quaternary ammonium compound, preferably used are nitrogen compounds such as phenazine compounds, safranin compounds, polyalkylene imines, thiourea derivatives, and polyacrylamide.

[0103] As the tertiary amine compound and the quaternary ammonium compound (nitrogen-containing organic compound), at least one compound selected from the above compounds can be used. These tertiary amine compounds and quaternary ammonium compounds (nitrogen-containing organic compounds) can be used alone or in combination of two or more.

[0104] The content of tertiary amine compounds and quaternary ammonium compounds (nitrogen-containing organic compounds) in the PR pulse electrolytic copper plating solution is not particularly limited and can be set to any range. The content of tertiary amine compounds and quaternary ammonium compounds (nitrogen-containing organic compounds) in the PR pulse electrolytic copper plating solution is preferably set to a range of less than 1 mg / L.

[0105] [1-8] Nonionic Polyether Polymer Surfactants

[0106] The copper plating solution for PR pulse electrolysis of the present invention preferably further contains a nonionic polyether polymer surfactant.

[0107] The nonionic polyether polymer surfactant is referred to as a polymer component. The nonionic polyether polymer surfactant is preferably used as an additive blended into a copper sulfate plating solution for through-hole plating or an additive blended into a copper sulfate plating solution for blind-hole plating.

[0108] The nonionic polyether polymer surfactant is preferably a polyether compound such as polyethylene glycol, polypropylene glycol, polyethylene oxide, polyoxyalkylene glycol, or the like.

[0109] As the nonionic polyether polymer surfactant, at least one compound selected from the above compounds can be used. These nonionic polyether polymer surfactants can be used alone or in combination of two or more.

[0110] The nonionic polyether polymer surfactant content in the PR pulse electrolysis copper plating solution is not particularly limited and can be set in any range. The nonionic polyether polymer surfactant content in the PR pulse electrolysis copper plating solution is preferably set in the range of 0.01 g / L to 10 g / L.

[0111] [1-9] Preferred PR Pulse Electrolysis Copper Plating Solution

[0112] The copper plating solution for PR pulse electrolysis of the present invention can achieve good effects particularly when the base bath is a copper sulfate plating solution. Specific examples of the composition of the copper sulfate plating solution are shown below.

[0113] Copper sulfate plating solution for PR pulse electrolysis

[0114] Copper (II) ion: contains 20 g / L to 300 g / L of copper sulfate pentahydrate.

[0115] Polyvalent metal ions: Contains 0.3g / L to 3g / L of iron ions (Fe 2+ ).

[0116] Unsaturated fatty acids: Contains 0.5g / L to 10g / L of fumaric acid, maleic acid, acetylenedicarboxylic acid, aconitic acid, etc.

[0117] Sulfuric acid: contains 20g / L~300g / L.

[0118] Chloride ion: Contains 5mg / L~200mg / L.

[0119] The PR pulse electrolytic copper plating solution of the present invention is an electrolytic copper plating solution used when electrolytic copper plating is performed by passing a PR pulse current.

[0120] [2] Copper plating method using PR pulse electrolysis

[0121] The copper plating method utilizing PR pulse electrolysis of the present invention comprises:

[0122] (1) In a PR pulse electrolytic copper plating solution, the object to be plated is used as the cathode and a PR pulse current is passed to perform electrolytic copper plating.

[0123] The copper plating solution for PR pulse electrolysis contains copper (II) ions, polyvalent metal ions (but not including copper (II) ions) and unsaturated fatty acids.

[0124] The PR pulse electrolytic copper plating solution of the present invention is an electrolytic copper plating solution used when electrolytic copper plating is performed by passing a PR pulse current.

[0125] [2-1] Anode / cathode current density ratio

[0126] The PR pulse current conduction conditions when using an electrolytic copper plating solution are as follows: the current density of the positive electrolysis for depositing the copper plating film is preferably set to 0.1 A / dm 2 (ASD)~10A / dm 2 (ASD), more preferably 1A / dm 2 (ASD)~5A / dm 2 (ASD) around.

[0127] The PR pulse current conditions when using an electrolytic copper plating solution are as follows: the current density of the negative (reverse) electrolysis for dissolving the copper plating film is preferably set to 0.1 A / dm 2 (ASD)~100A / dm 2 (ASD), more preferably 1A / dm 2 (ASD)~80A / dm 2 (ASD).

[0128] In the copper plating method using PR pulse electrolysis, step (1) is preferably performed under PR pulse electrolysis conditions of an anode / cathode current density ratio (anode current density / cathode current density) = 0.2 to 0.85.

[0129] [2-2] Positive current / negative current application time ratio

[0130] Positive current application time: The current application time during which copper is deposited on the plated object. The positive electrolysis time is preferably 5 to 200 msec, more preferably 10 to 100 msec.

[0131] Negative current application time: The current time during which copper is dissolved from the plated object. The negative (reverse) electrolysis time is preferably set to 0.1 msec to 10 msec.

[0132] In the copper plating method utilizing PR pulse electrolysis of the present invention, step (1) is preferably carried out under PR pulse electrolysis conditions in which the positive current application time is set to 5 milliseconds to 200 milliseconds and the positive current / negative current application time ratio (positive current application time / negative current application time) is greater than 5 and less than 50.

[0133] [2-3] Electrolytic copper plating

[0134] The temperature of the plating solution is preferably 10°C to 40°C.

[0135] The plating solution is preferably stirred by air stirring, jet stirring, or the like, and both may be used in combination.

[0136] When the plating treatment is performed, the anode is preferably any of a soluble anode and an insoluble anode. The soluble anode is preferably phosphorus-containing copper with a phosphorus content of 0.02 mass % to 0.06 mass %. In addition, the insoluble anode is preferably an anode coated with iridium oxide on titanium, an anode plated with platinum on titanium, etc. The shape of the anode is preferably a rod-shaped, spherical, plate-shaped, etc.

[0137] The type of the plated object (cathode) of the PR pulse electrolytic copper plating solution is not particularly limited. When the plated object is a substrate having micropores such as through holes and vias, the plated film can be uniformly formed even inside the micropores due to good uniform electrochemical deposition. The formed plated film has a good appearance and good physical properties such as elongation and tensile strength.

[0138] When plating is performed, the pretreatment method is not particularly limited. When a printed wiring board having through holes and vias is used as the plated object, the pretreatment method is as follows: (1) the plated object subjected to electroless copper plating used in the manufacture of the printed circuit board is degreased to remove dirt and the like attached in the previous process, (2) pickled to remove the oxide film, activated, and (3) immersed in the PR pulse electrolytic copper plating solution of the present invention, and PR pulse current is passed to perform electrolytic plating.

[0139] Conventionally, when plating is performed on a substrate having densely distributed through holes and vias, the surface area per unit area varies greatly, so the surface film thickness after the plating becomes non-uniform.

[0140] The PR pulse electrolysis copper plating solution of the present invention uses multivalent metal ions such as iron (II) ions and unsaturated fatty acids, and contains copper (II) ions such as copper sulfate aqueous solution. By using the PR pulse electrolysis copper plating solution of the present invention, it is possible to generate a copper coating with a uniform surface film thickness using pulse electrolysis. By using the PR pulse electrolysis copper plating solution of the present invention, the surface film thickness can be evenly distributed.

[0141] The copper plating solution for PR pulse electrolysis of the present invention is preferably an embodiment that does not contain a tertiary amine compound and a quaternary ammonium compound.

[0142] The copper plating solution for PR pulse electrolysis of the present invention can be used to perform copper plating by PR pulse electrolysis, thereby achieving good uniform electrochemical deposition and improving the appearance, film properties, filling properties, etc. of the formed plated film.

[0143] The PR pulse electrolytic copper plating solution of the present invention is useful when performing via-hole filling, through-hole filling, through-hole plating, and the like by electrolytic copper plating.

[0144] Example

[0145] Hereinafter, the present invention will be described in detail with reference to Examples.

[0146] The present invention is not limited to the following specific examples.

[0147] [1] Composition of copper sulfate plating solution

[0148] The copper plating solution for PR pulse electrolysis (copper sulfate plating solution) shown in Table 1 was prepared.

[0149] The plating time was adjusted so that the surface film thickness of the TH sparse portion would be 40 μm.

[0150] [Table 1]

[0151]

[0152] [2] Copper sulfate plating process

[0153] [Table 2]

[0154]

[0155] A substrate having a large number of through holes with a diameter of 0.3 mm and a depth of 1.6 mm and a 1 μm thick electroless copper plating film formed on the entire surface was used as the plated object. It was immersed in a degreasing solution (trade name: DP-320Clean, manufactured by Okuno Pharmaceutical Industry Co., Ltd., 100 mL / L aqueous solution) at 45°C for 5 minutes, washed with water for 1 minute, and immersed in 100 g / L dilute sulfuric acid for 1 minute for pretreatment.

[0156] Next, using a copper plating solution for PR pulse electrolysis, electrolytic copper plating was performed by PR pulse electrolysis under various plating conditions to form a copper plated film having a film thickness of 40 μm.

[0157] After electrolytic copper plating was performed by passing a PR pulse current, the thickness difference between the sparse and dense layers of the through-hole portion of the plated object was evaluated (uniform electrochemical deposition).

[0158] Plating conditions (Tables 3, 4 and 6 to 8)

[0159] Positive current density: 3.6A / dm 2

[0160] Negative current density: 7.2A / dm 2

[0161] Positive electrolysis time: 10msec

[0162] Negative electrolysis time: 0.6msec

[0163] Bath temperature: 25°C

[0164] Stirring: Jet stirring

[0165] Plating conditions (Table 5)

[0166] Positive current density: 3.6A / dm 2

[0167] Negative current density: 7.2A / dm 2 、10.8A / dm 2、18.0A / dm 2

[0168] Positive electrolysis time: 10msec

[0169] Negative electrolysis time: 0.3msec, 0.6msec, 1.0msec

[0170] Bath temperature: 25°C

[0171] Stirring: Jet stirring

[0172]

[0173]

[0174]

[0175]

[0176]

[0177] When the copper plating solution for PR pulse electrolysis of the present invention is used, the difference in the thickness of the formed plated film is less than 10 μm, the uniform electrochemical deposition property is excellent, and a copper plating film having good appearance and film properties can be formed.

[0178] On the other hand, when the PR pulse electrolytic copper plating solution of the comparative example was used, the difference in the dense and sparse film thickness of the formed plated film exceeded 10 μm, and the uniform electrochemical deposition property was poor.

[0179] [3] Industrial Applicability

[0180] The PR pulse electrolysis copper plating solution of the present invention uses multivalent metal ions such as iron (II) ions and unsaturated fatty acids, and contains copper (II) ions such as copper sulfate aqueous solution. By using the PR pulse electrolysis copper plating solution of the present invention, it is possible to generate a copper coating with a uniform surface film thickness by pulse electrolysis. By using the PR pulse electrolysis copper plating solution of the present invention, the surface film thickness of the copper coating can be evenly distributed.

Claims

1. A copper plating solution for PR pulse electrolysis, characterized in that: Contains copper (II) ions, polyvalent metal ions and unsaturated fatty acids, wherein the polyvalent metal ions do not include copper (II) ions, The copper plating solution for PR pulse electrolysis contains 0.3g / L to 3.0g / L of the polyvalent metal ions, 0.5g / L to 10g / L of the unsaturated fatty acids, and the total content of at least one amine compound selected from tertiary amine compounds and quaternary ammonium compounds is less than 1mg / L.

2. The copper plating solution for PR pulse electrolysis according to claim 1, characterized in that: The polyvalent metal ions are ions of at least one polyvalent metal selected from the group consisting of cobalt, iron and cerium.

3. The copper plating solution for PR pulse electrolysis according to claim 1, characterized in that: The polyvalent metal ion is at least one polyvalent metal ion selected from the group consisting of cobalt (II), iron (II) and cerium (III).

4. The copper plating solution for PR pulse electrolysis according to claim 1, characterized in that: The unsaturated fatty acid is at least one unsaturated fatty acid selected from olefins and alkynes.

5. The copper plating solution for PR pulse electrolysis according to claim 1, characterized in that: The unsaturated fatty acid is at least one unsaturated fatty acid selected from olefins and alkynes having two or three carboxyl groups.

6. The copper plating solution for PR pulse electrolysis according to claim 1, characterized in that: It also contains an acid component, and the copper plating solution for PR pulse electrolysis is an acidic aqueous solution.

7. The copper plating solution for PR pulse electrolysis according to claim 1, characterized in that: It also contains halide ions.

8. The copper plating solution for PR pulse electrolysis according to claim 1, characterized in that: It also contains sulfur-containing organic compounds.

9. A copper plating method using PR pulse electrolysis, characterized in that: The method comprises the following steps: (1) in a PR pulse electrolytic copper plating solution, the object to be plated is used as a cathode, a PR pulse current is passed through, and electrolytic copper plating is performed; The PR pulse electrolysis copper plating solution contains copper (II) ions, polyvalent metal ions and unsaturated fatty acids, wherein the polyvalent metal ions do not include copper (II) ions. The copper plating solution for PR pulse electrolysis contains 0.3g / L to 3.0g / L of the polyvalent metal ions, 0.5g / L to 10g / L of the unsaturated fatty acids, and the total content of at least one amine compound selected from tertiary amine compounds and quaternary ammonium compounds is less than 1mg / L.

10. The copper plating method using PR pulse electrolysis as claimed in claim 9, characterized in that: The step (1) is performed under PR pulse electrolysis conditions in which the anode / cathode current density ratio (anode current density / cathode current density) is 0.2 to 0.

85.

11. The copper plating method using PR pulse electrolysis as claimed in claim 9, characterized in that: The step (1) is performed under PR pulse electrolysis conditions in which the positive current application time is set to 5 to 200 milliseconds and the positive current / negative current application time ratio (positive current application time / negative current application time) is 5 or more and less than 50.

Images