CN116438331A

CN116438331A - Method for forming metal film

Info

Publication number: CN116438331A
Application number: CN202180074951.1A
Authority: CN
Inventors: 深泽宪正; 富士川亘; 白发润
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2020-11-05
Filing date: 2021-10-21
Publication date: 2023-07-14
Also published as: JP7205672B2; JPWO2022097486A1; TW202233889A; KR20230101816A; WO2022097486A1

Abstract

The invention provides a method for manufacturing a printed wiring board, which does not need to use chromic acid, permanganic acid to roughen the surface, alkali to form a surface modified layer, and the like, and does not use a vacuum device, wherein the printed wiring board has high adhesion between a substrate and a conductor circuit, has less undercut, and can obtain a wiring with good rectangular cross-section shape as a circuit wiring. It has been found that by forming a plating seed layer (M1) containing metal particles coated with a polymer dispersant on an insulating substrate (a) treated in an ozone atmosphere and then performing a plating treatment, a metal plating film excellent in adhesion can be formed on the substrate without forming a metal permeation layer on the surface of the substrate, and the present invention has been completed. Further, the present inventors have found that even when the primer layer (B) is formed on the insulating substrate (a) treated under an ozone atmosphere, a metal plating film excellent in adhesion can be formed on the substrate, and completed the present invention.

Description

Method for forming metal film

Technical Field

The present invention relates to a metal film forming method capable of forming a metal film on an insulating substrate with high adhesion.

Background

Members having a metal film formed on an insulating substrate are widely used for electronic devices such as printed wiring boards, electromagnetic wave shielding, decorative applications, and the like. As a method for forming a metal film on an insulating substrate, vacuum deposition, sputtering, and plating methods are used, but vacuum deposition or sputtering requires a vacuum apparatus, and thus has problems of limited substrate size and high cost, and wet plating methods are widely used.

Conventionally, in order to form a metal film on an insulating substrate by a wet plating method, the substrate surface is roughened to ensure adhesion between the substrate and the plated film by utilizing an anchor effect, but an environmentally-heavy reagent such as chromic acid or permanganic acid is used for the roughening treatment, and an alternative method using no such reagent is required. Further, the method of roughening the surface cannot be applied to a substrate in which transparency is important, a substrate in which chemical resistance is poor, or conversely, a substrate in which chemical resistance is too high is difficult to roughen the surface, and further, since the substrate surface is roughened, the surface of the metal film formed by plating also reflects the roughened surface of the substrate surface to form a surface having irregularities, it is necessary to increase the plating film thickness and to lengthen the plating time in order to obtain a glossy surface, and there are disadvantages that productivity is lowered, cost is increased, and the substrate weight is increased. Further, in recent years, in printed wiring board applications which deal with high density and high frequency, if roughness is formed on the surface by roughening treatment, there is a problem that it is difficult to form a narrow pitch circuit, signal delay is caused, and the like. Therefore, a technique for securing adhesion strength of a metal film formed on a substrate surface without roughening the substrate surface is required.

As a method for securing adhesion of a plated film without roughening treatment with chromic acid, permanganic acid, or the like, which is a large environmental load, a method for plating a substrate treated with an ozone-containing solution has been reported. For example, patent document 1 discloses an electroless plating method comprising: step 1, bringing a first solution containing ozone for activating unsaturated bonds on the surface of a resin substrate into contact with the surface of a substrate made of a resin having unsaturated bonds; step 2 of bringing a second solution containing a surfactant into contact with the surface of the resin substrate treated by bringing the second solution into contact with the first solution; step 3, adsorbing the catalyst on the surface of the resin substrate contacted with the second solution; and step 4, performing electroless plating on the surface of the resin base material on which the catalyst is adsorbed.

In the technique disclosed in patent document 1, in order to ensure the adhesion strength between the resin and the plating film, it is necessary to allow ozone to permeate into the resin by sufficiently bringing the resin surface into contact with ozone, but active species such as ozone and hydroxyl radicals contained in ozone water are likely to be decomposed, and the presence time in an aqueous solution is extremely short, so that the resin is often deactivated before permeation. Therefore, an aqueous solution having a high ozone concentration needs to be used. However, as described in patent document 2, when an aqueous ozone solution of high concentration is used, ozone remains on the resin surface, and there is a problem that metal deposition by electroless plating is inhibited by the strong oxidizing power of the remaining ozone.

As a countermeasure for this, patent document 2 discloses a technique in which a treatment of bringing a synthetic resin into contact with an aqueous ozone solution is performed as a pre-plating treatment, and after the aqueous ozone treatment, an ozone reduction treatment is performed to remove oxidizing power remaining on the surface of the synthetic resin, and then electroless plating and electrolytic plating are performed, but there is a problem in that the number of plating steps increases and the process becomes complicated.

Patent document 3 discloses that the problem with the method of the above 2 documents is that since an aqueous solution having a high ozone concentration is used in the pretreatment, ozone bubbled in the aqueous solution rises to the water surface and diffuses in the atmosphere, which deteriorates the working environment and deteriorates the health of the operator, and as a countermeasure for this, it has been proposed to carry out a surface modification treatment for modifying the surface of the substrate by contacting with ozone water containing ozone fine bubbles having an average particle diameter of 0.1 μm to 100 μm, and then to form a metal layer on the surface of the resin substrate by electroless plating.

Patent document 3 discloses that ozone in a fine bubble state stays in water for a long period of time, and therefore even in low-concentration ozone water, the ozone can be sufficiently brought into contact with the surface of a resin substrate to perform a modification treatment, and thus the production efficiency and the safety of the production environment can be improved.

According to the study of the group of patent document 3 (non-patent document 1), it is shown that a modified layer of the order of hundreds nm on the resin surface is formed by the resin surface treatment with ozone water, and the adhesion force of plating is ensured by infiltration of an electroless plating catalyst and precipitation of a plating film from the permeable layer.

Further, non-patent document 1 discloses that ozone is generated by irradiation with UV light and the surface of a substrate is modified, and it is shown that even in a gas phase, a catalyst or a metal plating permeation layer of about 100 nm is formed on the surface of a resin, thereby securing adhesion.

The above-mentioned penetration layer has a small possibility of increasing the roughness of the surface of the substrate and contributes to securing the adhesion on the non-roughened surface, but in the case where the penetration layer of the plating metal is formed, for example, in the case where the circuit is formed on the substrate, the insulation reliability may be lowered by the penetrated metal, and in particular, in the high-density wiring, there is a possibility that a serious influence may be exerted.

Further, the problem of the metal deposition defect in patent document 1 is that there is no permeation layer in which the electrolytic plating catalyst is present on the surface of the substrate, and it is necessary to establish a technique for maintaining the catalyst outside the modified layer on the surface of the substrate and ensuring adhesion between the substrate and the plating film.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2007-239084

Patent document 2: japanese patent application laid-open No. 2011-127155

Patent document 3: japanese patent laid-open No. 2013-189667

Non-patent literature

Non-patent document 1: "surface modification of various resins and study on functional coating formation technique", doctor's article at university of Kandong, ping Cheng for 1 month in 26 years, yi Su Shu, p.58

Disclosure of Invention

Problems to be solved by the invention

The present invention provides a plating treatment substrate which does not require surface roughening by chromic acid or permanganic acid, surface modified layer formation by alkali, etc., does not use a vacuum apparatus, has high adhesion between the substrate and a metal plating film, does not penetrate the metal to the substrate, and has excellent insulation reliability.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a plating treatment is performed by forming a plating seed layer (M1) containing metal particles coated with a polymer dispersant on an insulating substrate (a) treated in an ozone atmosphere, whereby a metal plating film excellent in adhesion can be formed on the substrate without forming a metal permeation layer on the surface of the substrate, and have completed the present invention.

The inventors of the present invention have found that a metal plating film excellent in adhesion can be formed on a substrate without forming a metal penetration layer on the surface of the substrate by forming a primer layer (B) on an insulating substrate (a) treated in an ozone atmosphere and further forming a plating seed layer (M1) containing metal particles coated with a polymer dispersant and performing a plating treatment, and completed the present invention.

Namely, the present invention relates to the following:

1. a method for forming a metal film, characterized by comprising:

step 1, treating an insulating substrate (A) in an ozone atmosphere;

step 2 of forming a metal particle layer (M1) containing metal particles coated with a polymer dispersant on the insulating substrate (A) treated in the ozone atmosphere;

and step 3 of forming a metal layer (M2) on the metal particle layer (M1) by a plating method.

2. A method for forming a metal film, characterized by comprising:

step 1, treating an insulating substrate (A) in an ozone atmosphere;

step 2' of forming a primer layer (B) on the insulating substrate (a) treated in the ozone atmosphere, and then forming a metal particle layer (M1) containing metal particles coated with a polymer dispersant on the primer layer (B);

3. A method for forming a metal film, characterized by comprising the steps of.

3. The method for forming a metal film according to claim 1 or 2, wherein the metal particles in the metal particle layer (M1) are 1 or more selected from the group consisting of at least silver, copper, nickel, gold, and platinum.

4. The method for forming a metal film according to 2 or 3, wherein the primer layer (B) is a resin having a reactive functional group [ X ], the polymer dispersant is a dispersant having a reactive functional group [ Y ], and a bond is formed between the reactive functional group [ X ] and the reactive functional group [ Y ].

5. The method for forming a metal film according to claim 4, wherein the reactive functional group [ Y ] is a basic nitrogen atom-containing group.

6. The method of forming a metal film according to claim 5, wherein the polymer dispersant having the reactive functional group [ Y ] is at least 1 selected from the group consisting of polyalkyleneimines and polyalkyleneimines having a polyoxyalkylene structure containing an oxyethylene unit.

7. The method for forming a metal film according to any one of claims 4 to 6, wherein the reactive functional group [ X ] is 1 or more selected from the group consisting of a ketone group, an acetoacetyl group, an epoxy group, a carboxyl group, an N-alkanol group, an isocyanate group, a vinyl group, a (meth) acryloyl group, and an allyl group.

8. The method for forming a metal film according to any one of claims 1 to 7, wherein the step 1 of treating the insulating substrate (a) in an ozone atmosphere is a step of bringing the insulating substrate (a) into contact with an aqueous solution containing ozone.

9. The method for forming a metal film according to any one of claims 1 to 7, wherein the step 1 of treating the insulating substrate (a) in an ozone atmosphere is a step of bringing the insulating substrate (a) into contact with an ozone-containing gas.

10. The method of forming a metal film according to claim 9, wherein the step of bringing the insulating substrate (A) into contact with the ozone-containing gas is performed by irradiating the insulating substrate (A) with Ultraviolet (UV) light in an atmosphere containing oxygen.

A method for forming a metal film, characterized by comprising:

step 1, treating an insulating substrate (A) in an ozone atmosphere;

step 2 of forming a metal particle layer (M1) containing metal particles coated with a polymer dispersant on the insulating substrate (A) treated in an ozone atmosphere;

Effects of the invention

By using the metal film forming method of the present invention, it is possible to apply a metal plating having high adhesion to a substrate having high transparency, a substrate having low chemical resistance, or a substrate having high chemical resistance, which is difficult to roughen the surface, without using a reagent having a large environmental load such as chromic acid or permanganic acid. Since the surface of the metal film formed by plating is not roughened, the surface of the metal film becomes a glossy surface reflecting the smooth surface of the substrate surface, and therefore the plating film thickness can be made thin, contributing to not only shortening the plating time and improving the productivity, but also contributing to the weight reduction of the substrate. Further, in recent years, in printed wiring board applications which deal with high density and high frequency, if irregularities are formed on the surface by roughening treatment, there are problems such as difficulty in forming a narrow pitch circuit, and causing signal delay, but by using the technique of the present invention, high adhesion strength can be ensured without roughening treatment of the substrate surface. Further, since the metal permeation layer is not formed on the surface of the base material, a printed wiring board having high insulation reliability can be provided when forming a circuit pattern.

Detailed Description

The step 1 of the present invention is a step of treating the insulating substrate (a) in an ozone atmosphere.

Examples of the material of the insulating base material (a) used in the present invention include: polyimide resins, polyamideimide resins, polyamide resins, polyethylene terephthalate resins, polybutylene terephthalate resins, polyethylene naphthalate resins, polycarbonate resins, acrylic resins such as acrylonitrile-butadiene-styrene (ABS) resins, polyarylate resins, polyacetal resins, polymethyl (meth) acrylate, polyvinylidene fluoride resins, polytetrafluoroethylene resins, polyvinyl chloride resins, polyvinylidene chloride resins, vinyl chloride resins having acrylic resins graft-copolymerized, polyvinyl alcohol resins, polyethylene resins, polypropylene resins, urethane resins, cycloolefin resins, polystyrene, liquid Crystal Polymers (LCP), polyetheretherketone (PEEK) resins, polyphenylene sulfide (PPS), polyphenylsulfone (PPSU), cellulose nanofibers, silicon carbide, gallium nitride, sapphire, ceramics, glass, diamond-like carbon (DLC), alumina, and the like.

As the insulating base material (a), a resin base material containing a thermosetting resin and an inorganic filler can be suitably used. Examples of the thermosetting resin include: epoxy resin, phenolic resin, unsaturated imide resin, cyanate resin, isocyanate resin, benzo

Oxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, melamine resins, and the like. On the other hand, examples of the inorganic filler include: silica, alumina, talc, mica, aluminum hydroxide, magnesium hydroxide,Calcium carbonate, aluminum borate, borosilicate glass, and the like. One kind of each of the thermosetting resin and the inorganic filler may be used, or two or more kinds may be used in combination.

As the form of the insulating base material (a), any of a flexible material, a rigid material, and a rigid-flexible material can be used. More specifically, commercially available materials molded into films, sheets, and plates may be used for the insulating base material (a), or materials molded into any shape from solutions, melts, and dispersions of the resins may be used. The insulating base material (a) may be a base material in which the resin material is formed on a conductive material such as a metal.

The insulating base material (a) may have a through-hole penetrating both surfaces of a planar base material such as a film, sheet, or plate, or may have a structure in which the base material is a laminate, the outer layer has a through-hole, the laminate has a non-through-hole throughout, and the laminate has a hole reaching the inner layer.

In the step 1 of the present invention, one embodiment of the method for treating the insulating substrate (a) in an ozone atmosphere is a method in which the insulating substrate (a) is immersed in an aqueous solution containing ozone. The concentration of ozone in the aqueous solution may be appropriately selected depending on the type of the substrate and the purpose of use of the substrate after the plating treatment, and is preferably in the range of 0.1 to 100ppm, and is preferably 0.1 to 50ppm from the viewpoint of improving the safety of the production environment of the operator due to the ozone volatilized from the ozone-containing aqueous solution. Ozone present in the aqueous solution is formed into bubbles having an average diameter of 0.05 to 100 μm, whereby the concentration of ozone can be further reduced, and an aqueous solution having a concentration of 0.1 to 10ppm can be suitably used.

The ozone concentration can be measured using a commercially available ozone concentration meter and an ultraviolet absorption type concentration meter. The size of the ozone bubbles can be measured by laser light scattering.

As a solvent used in the aqueous solution containing ozone, water is usually used, and if necessary, an organic acid such as an alcohol such as methanol, ethanol, or isopropanol, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, hexamethylphosphoramide, formic acid, or acetic acid may be used in combination with water. Further, an inorganic acid such as nitric acid, hydrochloric acid, hydrofluoric acid, or the like may be used in combination with water. The mixing amount of these solvents with respect to water is preferably 50% by mass or less, more preferably 30% by mass or less.

The temperature of the aqueous solution containing ozone is preferably set to 10 to 40 ℃. If the temperature is too high, the amount of dissolved ozone decreases, and the amount of ozone volatilized from the solution increases, so that it is difficult to perform treatment at a stable ozone concentration. On the other hand, when the temperature is too low, the treatment effect is poor.

The treatment time of the insulating substrate (a) in the ozone-containing aqueous solution may be appropriately selected depending on the type of the insulating substrate (a) to be used, the use of the final plating-treated substrate, and the productivity, and is preferably 1 to 60 minutes.

As a method for producing an aqueous solution containing ozone, a commercially available ozone water generator is simply used. In addition, in the case of bubbling ozone for use, a commercially available ozone nanobubble generator can be used.

In the step of the present invention, one embodiment of the method for treating the insulating substrate (a) in an ozone atmosphere is a method for bringing the insulating substrate (a) into contact with an ozone-containing gas. The ozone-containing gas may be any gas that is mixed with ozone generated by an ozone generator, and from the viewpoint of safety of an operator, a method of generating ozone by irradiating an insulating substrate (a) with Ultraviolet (UV) light in the presence of oxygen is preferable.

When ozone is generated by Ultraviolet (UV) light irradiation, light having a wavelength of 250nm or less can be used. Light of 185nm and 172nm contained in the mercury lamp is preferable because ozone is efficiently generated. In addition, 254nm light breaks down ozone to generate active oxygen. When a light source in which light of 250nm or less and light of 254nm are mixed is used, the surface treatment effect of ozone and active oxygen can be utilized.

The ultraviolet irradiation of the insulating substrate (a) is preferably performed in a chamber under an atmosphere of a nitrogen/oxygen mixed gas in which the concentration of oxygen is controlled. The concentration of oxygen in the nitrogen/oxygen gas atmosphere is preferably 0.1 to 20vol%.

The insulating substrate (a) may be subjected to degreasing and cleaning operations before being treated in an ozone atmosphere to remove dirt and oil during the substrate production. The insulating substrate (a) may be treated with an acid or an alkaline solvent before treatment under an ozone atmosphere, or may be subjected to a treatment such as surface swelling using an organic solvent.

It is considered that a hydrophilic permeation layer is formed by forming at least one functional group selected from c=o and c—oh on the surface of the insulating substrate (a) by the treatment under the ozone atmosphere. In the present invention, the metal particles can be fixed to the insulating base material (a) by penetrating the polymer dispersant or primer layer (B) of the metal-coated particles, which will be described later, into the penetration layer formed by the treatment under the ozone atmosphere, and chemically reacting the functional group formed by the ozone treatment with the polymer dispersant or primer layer (B) of the metal-coated particles.

In the step 2 of the present invention, a metal particle layer (M1) containing metal particles coated with a polymer dispersant is formed on the insulating substrate (a) treated in the ozone atmosphere in the step 1.

The metal particle layer (M1) serves as a plating underlayer when the metal layer (M2) is formed by a plating method in step 3 described later. The metal particles forming the metal particle layer (M1) may be suitably 1 or more kinds of metals selected from the group consisting of silver, copper, nickel, gold, platinum, palladium, ruthenium, tin, iron, cobalt, titanium, indium, iridium, and the like.

Among these metal particles, silver or copper particles are preferably used as the main component because they are relatively inexpensive and have a sufficiently low resistance value as the conductive metal layer, and silver particles are particularly preferably used as the main component because they are less likely to oxidize the surface even when they are stored under the atmosphere.

When silver particles are used as the main component, the metal particles may contain a metal other than silver, and when the metal other than silver is contained, the proportion of the metal other than silver is not particularly limited as long as plating in step 3 described later can be performed without any problem, and is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, relative to 100 parts by mass of silver.

When silver particles are used as the main component, the metal other than silver may be contained in the individual metal particles, or may be particles of a metal other than silver. As the metal substituted or mixed with silver, 1 or more metal elements selected from the group consisting of gold, platinum, palladium, ruthenium, tin, copper, nickel, iron, cobalt, titanium, indium, and iridium are exemplified.

In step 2 of the present invention, a dispersion of the metal particles is applied to the insulating substrate (a) to form a metal particle layer (M1) on the insulating substrate (a). The method for coating the metal particle dispersion is not particularly limited as long as the plating in step 3 described below can be satisfactorily performed, and various coating methods may be appropriately selected depending on the shape, size, degree of hardness and flexibility of the insulating substrate (a) to be used, and the like. Specific coating methods include, for example: gravure, offset, flexo, pad, gravure, relief, reverse relief, screen, micro-touch, reverse, pneumatic blade, air knife, squeeze, dip, transfer roll, contact, cast, spray, ink jet, die, spin, bar, dip, and the like.

The method of applying the metal particle dispersion liquid to both surfaces of the film, sheet or plate-like insulating substrate (a) is not particularly limited as long as the metal particle layer (M1) can be formed satisfactorily, and the application method exemplified above may be appropriately selected. In this case, the metal particle layer (M1) may be formed on both surfaces of the insulating substrate (a) at the same time, or may be formed on one surface of the insulating substrate (a) and then formed on the other surface. Further, in the case where the insulating base material (a) is a three-dimensional molded body, the above-described coating method may be appropriately selected according to the size and shape of the molded body, and a spray coating method, an inkjet method, a dip coating method, or the like is suitable.

After the metal particle dispersion is applied to the insulating substrate (a), the coating film is dried and fired to volatilize a solvent contained in the metal particle dispersion, and the metal particles are bonded to each other to form a metal particle layer (M1) on the insulating substrate (a). Here, the term "drying" mainly means a process of volatilizing a solvent from the dispersion of the metal particles, and the term "firing" mainly means a process of bonding the metal particles to each other.

The drying and firing may be performed simultaneously, or the coating film may be dried once and fired as needed before use. The temperature and time of drying may be appropriately selected depending on the type of solvent used in the silver particle dispersion liquid described later, and are preferably in the range of 20 to 250 ℃, and the time is preferably in the range of 1 to 200 minutes. The firing temperature and time are appropriately selected depending on the desired conductivity, and the temperature is preferably in the range of 80 to 350 ℃ and the time is preferably in the range of 1 to 200 minutes. In order to obtain a metal particle layer (M1) excellent in adhesion on the insulating substrate (a), the firing temperature is more preferably in the range of 80 to 250 ℃.

In the drying and firing, the air blowing may be performed or may not be performed particularly. The drying and firing may be performed in the atmosphere, under a substitution atmosphere of an inert gas such as nitrogen or argon, under an air flow, or under vacuum.

In the case where the insulating substrate (a) is a monolithic film, sheet, plate or three-dimensional molded body, the drying and firing of the coating film may be performed in a dryer such as a blower or a constant temperature dryer, in addition to the natural drying performed at the coating site. In the case where the insulating substrate (a) is a roll film or sheet, the roll material may be dried and fired by continuously moving the roll material in a non-heated or heated space provided after the coating step. Examples of heating methods for drying and firing at this time include methods using an oven, a hot air drying oven, an infrared drying oven, laser irradiation, microwaves, light irradiation (flash irradiation apparatus), and the like. These heating methods may be carried out by one kind, or two or more kinds may be used in combination.

The metal particle layer (M1) preferably contains metal particles in a range of 80 to 99.9 mass% and a polymer dispersant component described later in a range of 0.1 to 20 mass%.

The thickness of the metal particle layer (M1) is preferably in the range of 30 to 500nm, from the viewpoint that a more excellent plating underlayer can be formed in step 3 described later. In the plating step in step 3, in the case of directly performing electrolytic plating, the thickness of the metal particle layer (M1) is preferably 50 to 500nm. In the case where the metal particle layer (M1) is used as a conductive seed for the semi-additive method, the metal particle layer is preferably in the range of 40 to 200nm in order to further improve the removability in the seed etching step.

The thickness of the metal particle layer (M1) can be estimated by various known and customary methods, and for example, a cross-sectional observation method using an electron microscope and a method using fluorescent X-rays can be used, and a fluorescent X-ray method is preferably used.

In order to form the metal particle layer (M1), the metal particle dispersion liquid used in the present invention is a solution in which metal particles are dispersed in a solvent. The shape of the metal particles is not particularly limited as long as the metal particle layer (M1) is favorably formed, and various shapes of metal particles such as spherical, lenticular, polyhedral, flat, rod-like, and linear can be used. These metal particles may be used in a single shape, or two or more different shapes may be used in combination.

When the metal particles are spherical or polyhedral, the average particle diameter is preferably in the range of 1 to 20,000 nm. In addition, in the case of forming a fine circuit pattern, the average particle diameter is more preferably in the range of 1 to 200nm, and even more preferably in the range of 1 to 50nm, from the viewpoint that the uniformity of the metal particle layer (M1) can be further improved and the removability by the etching liquid can be further improved. The "average particle diameter" of the nano-sized particles is a volume average value measured by a dynamic light scattering method by diluting the silver particles with a good dispersion solvent. In this measurement, "Nanotrac UPA-150" manufactured by MICROTRAC corporation may be used.

On the other hand, when the metal particles have a lens-like, rod-like, wire-like shape or the like, the short diameter thereof is preferably in the range of 1 to 200nm, more preferably in the range of 2 to 100nm, and even more preferably in the range of 5 to 50 nm.

The metal particle dispersion for forming the metal particle layer (M1) is a dispersion of metal particles in various solvents, and the metal particles in the dispersion may be uniformly mono-dispersed in particle size distribution, or may be a mixture of particles having the average particle size range.

As the solvent used in the dispersion of the metal particles, an aqueous medium or an organic solvent can be used. Examples of the aqueous medium include distilled water, ion-exchanged water, pure water, ultrapure water, and mixtures thereof with an organic solvent mixed with the above water.

Examples of the organic solvent to be mixed with water include: alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, ethyl carbitol, ethyl cellosolve, and butyl cellosolve; ketone solvents such as acetone and methyl ethyl ketone; alkylene glycol solvents such as ethylene glycol, diethylene glycol, and propylene glycol; polyalkylene glycol solvents such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol; lactam solvents such as N-methyl-2-pyrrolidone, and the like.

The organic solvent used alone may be an alcohol compound, an ether compound, an ester compound, a ketone compound, or the like.

Examples of the alcohol solvent or ether solvent include: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, heptanol, hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, stearyl alcohol, allyl alcohol, cyclohexanol, terpineol, dihydroterpineol, 2-ethyl-1, 3-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, glycerol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, and the like.

Examples of the ketone solvent include: acetone, cyclohexanone, methyl ethyl ketone, and the like. Examples of the ester solvent include: ethyl acetate, butyl acetate, 3-methoxybutyl acetate, 3-methoxy-3-methylbutyl acetate, and the like. Further, examples of the other organic solvent include hydrocarbon solvents such as toluene, and particularly hydrocarbon solvents having 8 or more carbon atoms.

Examples of the hydrocarbon solvent having 8 or more carbon atoms include nonpolar solvents such as octane, nonane, decane, dodecane, tridecane, tetradecane, cyclooctane, xylene, mesitylene, ethylbenzene, dodecylbenzene, tetrahydronaphthalene, and trimethylbenzene cyclohexane, and may be used in combination with other solvents as needed. Further, a solvent such as mineral spirits and solvent naphtha may be used in combination as the mixed solvent.

The solvent is not particularly limited as long as it stably disperses the metal particles and the metal particle layer (M1) is favorably formed on the insulating substrate (a) or a primer layer (B) formed on the insulating substrate (a) described later. The solvent may be used alone or in combination of two or more. When the metal particle dispersion is directly applied to the insulating substrate (a) after the treatment under an ozone atmosphere, an aqueous medium having a high affinity with the hydrophilic surface formed by the treatment under an ozone atmosphere is preferably used.

The content of the metal particles in the metal particle dispersion is adjusted so as to have a viscosity optimal for coating application according to the coating method, and is preferably in the range of 0.5 to 90 mass%, more preferably in the range of 1 to 60 mass%, and even more preferably in the range of 2 to 10 mass%.

The metal particle dispersion preferably maintains long-term dispersion stability without aggregation, fusion and precipitation of the metal particles in the various solvents, and is coated with a polymer dispersant to disperse the metal particles in the various solvents. The polymer dispersant is preferably a dispersant having a functional group coordinated to the metal particles, and examples thereof include a dispersant having a functional group such as a carboxyl group, an amino group, a cyano group, an acetoacetyl group, a phosphorus atom-containing group, a thiol group, a thiocyanato group, or a glycine group.

As the polymer dispersant, a commercially available or independently synthesized dispersant may be used, and is appropriately selected depending on the purpose of the solvent in which the metal particles are dispersed, the type of the insulating substrate (a) to which the metal particle dispersion is applied, and the like, and when the metal particles are directly applied to the insulating substrate (a) without using the primer layer (B) described later, it is preferable that the polymer dispersant penetrate into the permeable layer formed on the surface of the insulating substrate (a) by the treatment under an ozone atmosphere and has a reactive functional group capable of forming a bond with a functional group such as c=o or c—oh formed by the treatment under an ozone atmosphere.

Here, in the case of forming the metal particle layer (M1) on the primer layer (B) described later, it is preferable to use a compound having a reactive functional group [ Y ] capable of forming a bond with a reactive functional group [ X ] of a resin to be used for the primer layer (B) described later, from the viewpoint of improving adhesion of the 2 layers.

Examples of the compound having the reactive functional group [ Y ] include compounds having an amino group, an amide group, an alkanolamide group, a carboxyl group, a carboxylic anhydride group, a carbonyl group, an acetoacetyl group, an epoxy group, an alicyclic epoxy group, an oxetane ring, a vinyl group, an allyl group, a (meth) acryloyl group, a (blocked) isocyanate group, an (alkoxy) silyl group, and the like, and silsesquioxane compounds. In particular, the reactive functional group [ Y ] is preferably a basic nitrogen-containing group, in view of further improving the adhesion between the primer layer (B) and the conductive metal layer (M1). Examples of the basic nitrogen atom-containing group include: imino, primary amino, secondary amino, and the like.

The basic nitrogen atom-containing group may be present singly or in plural in the molecule of the dispersant 1. By containing a plurality of basic nitrogen atoms in the dispersant, a part of the basic nitrogen atom-containing groups interact with silver particles to contribute to dispersion stability of the metal particles, and the remaining basic nitrogen atom-containing groups contribute to improvement of adhesion to the insulating substrate (a). In addition, when a resin having a reactive functional group [ X ] is used for the primer layer (B) described later, a bond can be formed between the basic nitrogen-containing group in the dispersant and the reactive functional group [ X ], and adhesion of the metal plating layer (M2) described later to the insulating substrate (a) can be further improved, which is preferable.

The polymer dispersant is preferably a polyalkyleneimine such as polyethyleneimine or polypropyleneimine, a compound obtained by adding a polyoxyalkylene group to the polyalkyleneimine, or the like, from the viewpoint that the polymer dispersant can exhibit stability and coatability of a metal particle dispersion and form a metal particle layer (M1) that exhibits good adhesion to the insulating substrate (a).

The compound obtained by adding a polyoxyalkylene group to the above-mentioned polyalkyleneimine may be a compound obtained by bonding a polyethyleneimine and a polyoxyalkylene group in a straight chain, or may be a compound obtained by grafting a polyoxyalkylene group to a main chain composed of the above-mentioned polyethyleneimine on a side chain thereof.

Specific examples of the compound obtained by adding a polyoxyalkylene group to the polyalkyleneimine include: a block copolymer of polyethyleneimine and polyoxyethylene; a compound having a polyoxyethylene structure, wherein a part of an imino group present in a main chain of a polyethyleneimine is added to ethylene oxide; and a compound obtained by reacting an amino group of a polyalkyleneimine, a hydroxyl group of a polyoxyethylene glycol, and an epoxy group of an epoxy resin.

Examples of the commercial products of the polyalkyleneimines include "PAO2006W", "PAO306", "PAO318" and "PAO718" of "EPOMIN (registered trademark) PAO series" manufactured by japan catalyst, inc.

The number average molecular weight of the polyalkyleneimine is preferably in the range of 3,000 to 30,000.

The amount of the dispersant used for dispersing the metal particles is preferably in the range of 0.01 to 50 parts by mass based on 100 parts by mass of the metal particles, and is preferably in the range of 0.1 to 10 parts by mass based on 100 parts by mass of the metal particles, and is more preferably in the range of 0.1 to 5 parts by mass based on the conductivity of the metal particle layer (M1) from the viewpoint of forming a metal particle layer (M1) which exhibits good adhesion to the insulating substrate (a) or a primer layer (B) described later.

The method for producing the metal particle dispersion is not particularly limited, and various methods can be used for producing the metal particle dispersion, and for example, metal particles produced by a vapor phase method such as a low vacuum vapor phase evaporation method may be dispersed in a solvent, or a metal compound may be reduced in a liquid phase to directly produce a dispersion of metal particles. The solvent composition of the dispersion liquid at the time of production and the dispersion liquid at the time of coating can be changed by changing the solvent and adding the solvent as needed, as appropriate, in both the gas-phase and liquid-phase methods. Among the gas phase and liquid phase methods, the liquid phase method is particularly suitable from the viewpoints of stability of the dispersion and simplicity of the production process. The liquid phase method can be produced, for example, by reducing metal ions in the presence of the polymer dispersant.

The dispersion of the metal particles may further contain, if necessary, an organic compound such as a surfactant, a leveling agent, a viscosity modifier, a film-forming aid, a defoaming agent, and a preservative.

Examples of the surfactant include: nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene sorbitol tetraoleate, and polyoxyethylene-polyoxypropylene copolymer; anionic surfactants such as fatty acid salts such as sodium oleate, alkyl sulfate salts, alkylbenzene sulfonate salts, alkyl sulfosuccinate salts, naphthalene sulfonate salts, polyoxyethylene alkyl sulfate salts, sodium alkane sulfonate salts, and sodium alkyl diphenyl ether sulfonate salts; cationic surfactants such as alkylamine salts, alkyltrimethylammonium salts and alkyldimethylbenzyl ammonium salts.

As the leveling agent, a general leveling agent can be used, and examples thereof include: silicone compounds, acetylene glycol compounds, fluorine compounds, and the like.

As the viscosity modifier, a general thickener can be used, and examples thereof include: acrylic polymers which can be thickened by adjustment to alkaline, synthetic rubber latex, urethane resins which can be thickened by molecular association, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, polyvinyl alcohol, hydrogenated castor oil, amide wax, oxidized polyethylene, metal soaps, dibenzylidene sorbitol, and the like.

As the above-mentioned film forming auxiliary agent, general film forming auxiliary agents can be used, and examples thereof include: anionic surfactants such as dioctyl sulfosuccinate sodium salt, hydrophobic nonionic surfactants such as sorbitan monooleate, polyether modified silicone, silicone oil, and the like.

As the above-mentioned antifoaming agent, general antifoaming agents can be used, and examples thereof include: silicone-based antifoaming agents, nonionic surfactants, polyethers, higher alcohols, polymer-based surfactants, and the like.

As the above-mentioned preservative, general ones can be used, and examples thereof include: isothiazoline-based preservatives, triazine-based preservatives, imidazole-based preservatives, pyridine-based preservatives, azole-based preservatives, pyrithione (pyrithione) -based preservatives, and the like.

In addition, as a more preferable embodiment of the present invention, there is a method (step 1') of forming a metal particle layer (M1) containing metal particles on an insulating substrate (a) after forming a primer layer (B) on the insulating substrate (a) before forming the metal particle layer (M1) containing metal particles on the insulating substrate (a). The method of providing the primer layer is preferable from the viewpoint of suppressing permeation of metal into the permeation layer formed on the surface of the insulating substrate (a) by the treatment under the ozone atmosphere, and further preferable from the viewpoint of enabling further improvement of adhesion of the metal plating layer (M2) to the insulating substrate (a).

The primer layer (B) may be formed by coating a primer on a part or the entire surface of the insulating substrate (a), and removing a solvent such as an aqueous medium or an organic solvent contained in the primer. The primer is used to improve adhesion of the plated metal layer (M2) to the insulating substrate (a), and is a liquid composition obtained by dissolving or dispersing various resins described later in a solvent.

The method of applying the primer to the insulating substrate (a) is not particularly limited as long as the primer layer (B) can be formed satisfactorily, and various application methods may be appropriately selected depending on the shape, size, degree of hardness and flexibility of the insulating substrate (a) to be used. Specific coating methods include, for example: gravure, offset, flexo, pad, gravure, relief, reverse relief, screen, micro-touch, reverse, pneumatic blade, air knife, squeeze, dip, transfer roll, contact, cast, spray, ink jet, die, spin, bar, dip, and the like.

The method of applying the primer to both surfaces of the insulating substrate (a) in the form of a film, sheet or plate is not particularly limited as long as the primer layer (B) can be formed well, and the application method exemplified above may be appropriately selected. In this case, the primer layer (B) may be formed on both surfaces of the insulating substrate (a) at the same time, or may be formed on one surface of the insulating substrate (a) and then formed on the other surface. Further, in the case where the insulating base material (a) is a three-dimensional molded body, the above-described coating method may be appropriately selected according to the size and shape of the molded body, and a spray coating method, an inkjet method, a dip coating method, or the like is suitable.

As a method of forming the primer layer (B) by applying the primer to the surface of the insulating substrate (a) and then removing the solvent contained in the applied layer, for example, a method of drying the primer layer using a dryer to evaporate the solvent is generally used. The drying temperature may be set to a temperature in a range that allows the solvent to volatilize and does not adversely affect the insulating substrate (a), and may be room temperature drying or heat drying. The specific drying temperature is preferably in the range of 20 to 350 ℃, more preferably in the range of 60 to 300 ℃. The drying time is preferably in the range of 1 to 200 minutes, more preferably in the range of 1 to 60 minutes.

The drying may be performed by blowing or not particularly by blowing. The drying may be performed in the atmosphere, under a substitution atmosphere or a gas flow of nitrogen, argon, or the like, or under vacuum.

In the case where the insulating base material (a) is a film, sheet, plate, or molded article of a three-dimensional shape, the insulating base material (a) may be naturally dried at the application site, or may be dried in a dryer such as a blower or a thermostatic dryer. In the case where the insulating substrate (a) is a roll film or a roll sheet, the roll material may be dried by continuously moving the roll material in a non-heated or heated space provided after the coating step.

The thickness of the primer layer (B) may be appropriately selected depending on the application of the plating-treated product produced by the present invention, and is preferably in the range of 10nm to 30 μm, more preferably in the range of 10nm to 1 μm, and even more preferably in the range of 10nm to 500nm, from the viewpoint of further improving the adhesion between the insulating substrate (a) and the plating metal layer (M2).

The resin forming the primer layer (B) preferably permeates easily into the permeable layer formed by the treatment of the insulating substrate (a) in an ozone atmosphere and has a functional group capable of binding to the functional group formed by the treatment in an ozone atmosphere, and further, when a substance having a reactive functional group [ Y ] is used as the dispersant for the metal particles, it is preferably a resin having a reactive functional group [ X ] reactive to the reactive functional group [ Y ]. Examples of the reactive functional group [ X ] include an amino group, an amide group, an alkanolamide group, a ketone group, a carboxyl group, a carboxylic anhydride group, a carbonyl group, an acetoacetyl group, an epoxy group, an alicyclic epoxy group, an oxetane ring, a vinyl group, an allyl group, a (meth) acryloyl group, a (blocked) isocyanate group, and an (alkoxy) silyl group. In addition, a silsesquioxane compound may be used as the compound forming the primer layer (B).

In particular, in the case where the reactive functional group [ Y ] in the dispersant is a basic nitrogen atom-containing group, the resin forming the primer layer (B) is preferably a resin having a ketone group, a carboxyl group, a carbonyl group, an acetoacetyl group, an epoxy group, an alicyclic epoxy group, an alkanolamide group, an isocyanate group, a vinyl group, a (meth) acryl group, or an allyl group as the reactive functional group [ X ] in view of further improving the adhesion of the plated metal layer (M2) on the insulating substrate (a).

Examples of the resin for forming the primer layer (B) include: urethane resins, acrylic resins, core-shell type composite resins having a urethane resin as a shell and an acrylic resin as a core, epoxy resins, imide resins, amide resins, melamine resins, phenol resins, urea resins, blocked isocyanate polyvinyl alcohols obtained by reacting polyisocyanates with blocking agents such as phenol, polyvinyl pyrrolidone, and the like. The core-shell type composite resin having a urethane resin as a shell and an acrylic resin as a core can be obtained, for example, by polymerizing an acrylic monomer in the presence of the urethane resin. In addition, one kind of these resins may be used, or two or more kinds may be used in combination.

Among the resins for forming the primer layer (B), a resin that generates a reducing compound by heating is preferable in view of further improving the adhesion of the plated metal layer (M2) on the insulating substrate (a). Examples of the reducing compound include: phenol compounds, aromatic amine compounds, sulfur compounds, phosphoric acid compounds, aldehyde compounds, and the like. Among these reducing compounds, phenol compounds and aldehyde compounds are preferable.

When a resin that generates a reducing compound by heating is used for the primer, a reducing compound such as formaldehyde or phenol is generated in the heat drying step when the primer layer (B) is formed. Specific examples of the resin that generates the reducing compound by heating include: a resin obtained by polymerizing a monomer containing an N-alkanol (meth) acrylamide, a core-shell type composite resin having a urethane resin as a shell and a resin obtained by polymerizing a monomer containing an N-alkanol (meth) acrylamide as a core, a urea-formaldehyde-methanol condensate, a urea-melamine-formaldehyde-methanol condensate, a formaldehyde adduct of a poly (N-alkoxymethylol (meth) acrylamide) or a poly (meth) acrylamide, a melamine resin, or the like, which generates formaldehyde by heating; phenolic resins, phenol blocked isocyanates, and the like, and resins that generate phenol compounds by heating. Among these resins, preferred are core-shell type composite resins having a urethane resin as a shell and a resin obtained by polymerizing a monomer containing an N-alkanol group (meth) acrylamide as a core, melamine resins, and phenol blocked isocyanates, from the viewpoint of improving adhesion.

In the present invention, "(meth) acrylamide" means one or both of "methacrylamide" and "acrylamide", and "(meth) acrylic acid" means one or both of "methacrylic acid" and "acrylic acid".

The resin which generates a reducing compound by heating can be obtained by polymerizing a monomer having a functional group which generates a reducing compound by heating by a polymerization method such as radical polymerization, anionic polymerization, cationic polymerization, or the like.

Examples of the monomer having a functional group which generates a reducing compound by heating include N-alkoxyvinyl monomers, specifically, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-isopropoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, N-pentoxymethyl (meth) acrylamide, N-ethanol (meth) acrylamide, N-propanol (meth) acrylamide, and the like.

In the production of the resin which generates a reducing compound by heating, various other monomers such as alkyl (meth) acrylate may be copolymerized together with a monomer having a functional group which generates a reducing compound by heating.

In the case of using the blocked isocyanate as the resin for forming the primer layer (B), the primer layer (B) is formed by forming an uretdione bond by self-reaction between isocyanate groups or by forming a bond between isocyanate groups and functional groups of other components. The bond formed in this case may be formed before the silver particle dispersion is applied, or may be formed by heating after the silver particle dispersion is applied, instead of before the silver particle dispersion is applied.

Examples of the blocked isocyanate include those having a functional group formed by blocking an isocyanate group with a blocking agent.

The blocked isocyanate preferably has the above functional group in the range of 350 to 600g/mol per 1 mol of blocked isocyanate.

From the viewpoint of improving adhesion, the functional groups are preferably 1 to 10, more preferably 2 to 5, per 1 molecule of the blocked isocyanate.

The number average molecular weight of the blocked isocyanate is preferably in the range of 1,500 to 5,000, more preferably in the range of 1,500 to 3,000, from the viewpoint of improving adhesion.

Further, the blocked isocyanate preferably has an aromatic ring from the viewpoint of further improving adhesion. Examples of the aromatic ring include phenyl and naphthyl.

The blocked isocyanate can be produced by reacting a part or all of the isocyanate groups of the isocyanate compound with a blocking agent.

Examples of the isocyanate compound that is a raw material for the blocked isocyanate include: polyisocyanate compounds having an aromatic ring such as 4,4 '-diphenylmethane diisocyanate, 2,4' -diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate, etc.; aliphatic polyisocyanate compounds such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, m-xylylene diisocyanate, tetramethyl m-xylylene diisocyanate, and the like, and polyisocyanate compounds having an alicyclic structure. Further, the above polyisocyanate compounds may be exemplified by biuret, isocyanurate, and adduct thereof.

The isocyanate compound may be obtained by reacting the polyisocyanate compound exemplified above with a compound having a hydroxyl group or an amino group, or the like.

When an aromatic ring is introduced into the blocked isocyanate, a polyisocyanate compound having an aromatic ring is preferably used. Among the polyisocyanate compounds having an aromatic ring, 4 '-diphenylmethane diisocyanate, toluene diisocyanate, isocyanurate of 4,4' -diphenylmethane diisocyanate, and isocyanurate of toluene diisocyanate are preferable.

Examples of the blocking agent used in the production of the blocked isocyanate include: phenol compounds such as phenol and cresol; lactam compounds such as epsilon-caprolactam, delta-valerolactam and gamma-butyrolactam; oxime compounds such as formamide oxime, aldoxime, acetone oxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, and cyclohexanone oxime; 2-hydroxypyridine, butyl cellosolve, propylene glycol monomethyl ether, benzyl alcohol, methanol, ethanol, n-butanol, isobutanol, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, butyl mercaptan, dodecyl mercaptan, acetanilide, acetamide, succinimide, maleimide, imidazole, 2-methylimidazole, urea, thiourea, ethyleneurea, diphenylaniline, aniline, carbazole, ethyleneimine, polyethyleneimine, 1H-pyrazole, 3-methylpyrazole, 3, 5-dimethylpyrazole, and the like. Among them, a blocking agent capable of dissociating and forming an isocyanate group by heating in the range of 70 to 200 ℃ is preferable, and a blocking agent capable of dissociating and forming an isocyanate group by heating in the range of 110 to 180 ℃ is more preferable. Specifically, phenol compounds, lactam compounds and oxime compounds are preferable, and particularly, phenol compounds are more preferable because they become reducing compounds when the capping agent is detached by heating.

Examples of the method for producing the blocked isocyanate include: a method of mixing and reacting the isocyanate compound produced in advance with the blocking agent; and a method in which the blocking agent is mixed with a raw material used for producing the isocyanate compound and reacted with the raw material.

More specifically, the above blocked isocyanate can be produced by: the polyisocyanate compound is reacted with a compound having a hydroxyl group or an amino group to thereby produce an isocyanate compound having an isocyanate group at the end, and then the isocyanate compound is mixed with the blocking agent and reacted.

The content ratio of the blocked isocyanate obtained by the above method in the resin forming the above primer layer (B) is preferably in the range of 50 to 100 mass%, more preferably in the range of 70 to 100 mass%.

Examples of the melamine resin include: mono-or poly-methylolmelamine obtained by adding 1 to 6 moles of formaldehyde to 1 mole of melamine; an etherate of (poly) methylolmelamine such as trimethoxymethylolmelamine, tributoxy methylolmelamine, or hexamethoxy methylolmelamine (the degree of etherification is arbitrary); urea-melamine-formaldehyde-methanol condensates and the like.

In addition, in addition to the method of using a resin that generates a reducing compound by heating as described above, a method of adding a reducing compound to a resin may be mentioned. In this case, examples of the reducing compound to be added include: phenolic antioxidants, aromatic amine antioxidants, sulfur antioxidants, phosphoric antioxidants, vitamin C, vitamin E, sodium ethylenediamine tetraacetate, sulfite, hypophosphorous acid, hypophosphite, hydrazine, formaldehyde, sodium borohydride, dimethylamine borane, phenol, and the like.

In the present invention, the method of adding a reducing compound to a resin is more preferably a method of using a resin that generates a reducing compound by heating, because the electric characteristics may be lowered due to the final residual low molecular weight component or ionic compound.

The primer used for forming the primer layer (B) preferably contains 1 to 70 mass% of the resin in the primer, more preferably 1 to 20 mass% in view of coatability and film-forming property.

The solvent that can be used for the primer may be various organic solvents or aqueous media. Examples of the organic solvent include toluene, ethyl acetate, methyl ethyl ketone, and cyclohexanone, and examples of the aqueous medium include water, an organic solvent mixed with water, and a mixture thereof.

In addition, the resin forming the primer layer (B) may have, for example, an alkoxysilyl group, a silanol group, a hydroxyl group, an amino group, or the like, which contributes to a crosslinking reaction, as required. The crosslinked structure formed by these functional groups may be formed before the step of forming the metal particle layer (M1) containing silver particles in the subsequent step, or may be formed after the step of forming the metal particle layer (M1) containing metal particles. In the case where the crosslinked structure is formed after the step of forming the metal particle layer (M1) containing metal particles, the crosslinked structure may be formed in advance in the primer layer (B) before the step of forming the plated metal layer (M2), or the crosslinked structure may be formed in the primer layer (B) after the step of forming the plated metal layer (M2), for example, by aging.

The primer layer (B) may be used by adding a known substance as needed, and a pH adjuster, a film forming aid, a leveling agent, a thickener, a water repellent, a defoaming agent, and the like may be added as well as a crosslinking agent.

Examples of the crosslinking agent include metal chelate compounds, polyamine compounds, aziridine compounds, metal salt compounds, isocyanate compounds, and the like, and examples thereof include thermal crosslinking agents, melamine compounds, epoxy compounds, and the like that react at a relatively low temperature of about 25 to 100 ℃ to form a crosslinked structure,

The heat crosslinking agent and various photocrosslinkers are formed by reacting an oxazoline compound, a carbodiimide compound, a blocked isocyanate compound, or the like at a relatively high temperature of 100 ℃ or higher to form a crosslinked structure.

The amount of the crosslinking agent used varies depending on the type, but is preferably in the range of 0.01 to 60 parts by mass, more preferably in the range of 0.1 to 10 parts by mass, and even more preferably in the range of 0.1 to 5 parts by mass, relative to 100 parts by mass of the total resin contained in the primer, from the viewpoint of improving the adhesion of the metal coating layer (M2) to the substrate.

In the case of using the above-mentioned crosslinking agent, the crosslinked structure may be formed before the step of forming the metal particle layer (M1) containing metal particles in the subsequent step, or the crosslinked structure may be formed after the step of forming the metal particle layer (M1) containing metal particles. In the case where the crosslinked structure is formed after the step of forming the metal particle layer (M1) containing metal particles, the crosslinked structure may be formed in the primer layer (B) before the step of forming the plated metal layer (M2), or the crosslinked structure may be formed in the primer layer (B) after the step of forming the plated metal layer (M2), for example, by curing.

In the step 1' of the present invention, the method of forming the metal particle layer (M1) containing metal particles on the primer layer (B) is the same as the method of forming the metal particle layer (M1) containing metal particles on the insulating substrate (a).

In addition, the primer layer (B) may be subjected to a surface treatment before the metal particle dispersion is applied, for the purpose of improving the coatability of the metal particle dispersion and improving the adhesion of the plated metal layer (M2) to the substrate, as in the case of the insulating substrate (a).

Examples of the plating method to be performed in step 3 of the present invention include electroless plating, electrolytic plating, and a method of combining electroless plating and electrolytic plating. In the case of performing electroless plating as the plating method, the metal particle layer (M1) serves as a catalyst seed. The plating layer (M2) may be formed by forming a thick film only by electroless plating, or may be formed by further performing electrolytic plating using an electroless plating layer formed by electroless plating as a conductive seed, thereby forming the plating layer (M2) into a thick film. Further, in the case where the electroless plating is directly performed without performing the electroless plating, the metal particle layer (M1) serves as a conductive seed. The plating layer (M2) may be formed by electrolytic plating after electroless plating. When electrolytic plating is used in combination, the plating deposition rate can be increased, and thus the production efficiency can be advantageously improved.

In the case of forming the metal plating layer (M2) by electroless plating, examples of the plating metal include copper, nickel, chromium, cobalt-tungsten-boron, tin, and the like. When the metal plating layer (M2) is a conductor circuit pattern, copper is preferably used among these metals because of low resistance. As described above, the metal plating layer (M2) may be formed by performing electrolytic plating after electroless plating. When electrolytic plating is used in combination, the plating deposition rate can be increased, and thus the production efficiency can be advantageously improved.

In the step 3 of the present invention, when electroless plating and electrolytic plating are used to form the metal plating layer (M2), the deposition metals of the electroless plating and the electrolytic plating may be the same or different. For example, there may be mentioned: electroless copper plating, electroless nickel plating, electrolytic nickel plating, electroless cobalt plating, and electrolytic copper plating. When the metal plating layer (M2) is a circuit pattern, copper is preferably used as a main metal constituting the metal plating layer (M2) in view of low resistance, and diffusion of copper into a substrate can be suppressed by combining electroless nickel plating, electroless cobalt plating, and the like, so that the long-term reliability of the printed wiring board can be improved.

In the step 3 of the present invention, in the case where electroless plating and electrolytic plating are used to form the metal plating layer (M2), the thickness of the electroless plating layer is appropriately selected as needed, and in order to ensure the conductivity for appropriately performing the electrolytic plating, the range of 0.1 μm to 2 μm is preferable, and the range of 0.15 μm to 1 μm is more preferable from the viewpoint of improving productivity.

In step 3, when electrolytic plating is directly performed, examples of the plating metal constituting the metal plating layer (M2) include copper, nickel, chromium, zinc, tin, gold, silver, rhodium, palladium, and platinum. Among these metals, copper is preferable in terms of low cost and low resistance, and the metal plating layer (M2) is preferably formed by electrolytic copper plating, as described above, in the case where the metal pattern to be formed is a circuit pattern. The electrolytic copper plating may be carried out by a known and conventional method, and a copper sulfate plating method using a copper sulfate bath is preferable.

In the case of directly performing the electrolytic plating method, the plating metal constituting the metal plating layer (M2) may be used in combination of 1 or more of the above-mentioned various metals. For example, in the case where the metal plating layer (M2) formed is used for decoration, copper plating is performed on the lower layer of the outermost nickel-chromium plating for the purpose of relaxing the stress of the plated metal. The copper plating to be performed at this time may be performed by electrolytic plating of nickel on the metal particle layer (M1), then electrolytic plating of copper, further electrolytic plating of nickel and electrolytic plating of chromium, or may be performed by electrolytic plating of copper on the metal particle layer (PM 1), then electrolytic plating of nickel and electrolytic plating of chromium.

In the metal film forming method of the present invention, the metal plating layer (M2) formed on the insulating substrate (a) may be patterned. As a method for patterning the plated metal layer (M2), the above steps 1 to 3 may be performed to form the plated metal layer (M2) on the entire surface of the insulating substrate (a), and then the unnecessary portion may be removed to perform patterning, or the following method may be employed: in step 2, a pattern resist is formed on the metal particle layer (M1), and in step 3, after the plated metal layer (M2) is formed only in the desired pattern portion, the resist is stripped, and the metal particle layer (M1) in the unnecessary portion is etched away. The unnecessary part of the metal particle layer (M1) formed in step 2 may be removed by a mechanical method such as scribing or laser irradiation, and the metal particle layer (M1) of the pattern part may be left, and the metal particle layer (M1) may be used as a seed to form a plating layer of the pattern part.

By using the metal film forming method of the present invention described above, it is possible to apply a metal plating having high adhesion to a substrate having high transparency, a substrate having low chemical resistance, or a substrate having high chemical resistance, which is difficult to roughen the surface, without using a reagent having a large environmental load such as chromic acid or permanganic acid. Since the surface of the substrate is not roughened, the surface of the metal film formed by plating becomes a glossy surface reflecting the smooth surface of the substrate surface, and therefore the plating film thickness can be made thin, contributing to not only shortening the plating time and improving the productivity, but also contributing to the weight reduction of the substrate. Further, in recent years, in printed wiring board applications which deal with high density and high frequency, if irregularities are formed on the surface by roughening treatment, there are problems such as difficulty in forming a narrow pitch circuit, and causing signal delay, but by using the technique of the present invention, high adhesion strength can be ensured without roughening treatment of the substrate surface. Further, since the metal permeation layer is not formed on the surface of the base material, a printed wiring board having high insulation reliability can be provided when forming a circuit pattern. In addition, according to the metal film forming method of the present invention, not only a printed wiring board but also various members having a patterned metal layer on the surface of a substrate, for example, a connector, an electromagnetic wave shield, an antenna such as an RFID, a film capacitor, and the like can be manufactured. The metal coating forming method of the present invention can be suitably used for decorative plating applications in which a patterned metal layer is provided on a substrate of various shapes and sizes.

Examples

The present invention will be described in detail with reference to examples.

Production example 1: production of primer resin (B-1)

9.2 parts by mass of 2, 2-dimethylolpropionic acid, 57.4 parts by mass of polymethylene polyphenyl polyisocyanate (Milliconate MR-200 manufactured by Tosoh Co., ltd.) and 233 parts by mass of methyl ethyl ketone were added to a reaction vessel provided with a thermometer, a nitrogen inlet pipe, a stirrer and replaced with nitrogen, and reacted at 70℃for 6 hours to obtain an isocyanate compound. Then, 26.4 parts by mass of phenol was supplied as a blocking agent into the reaction vessel, and reacted at 70℃for 6 hours. Thereafter, cooled to 40℃to obtain a blocked isocyanate solution.

[ preparation example 1: preparation of silver particle Dispersion

A dispersion containing silver particles and a dispersant was prepared by dispersing silver particles having an average particle diameter of 30nm in a mixed solvent of 45 parts by mass of ethylene glycol and 55 parts by mass of ion-exchanged water using a compound obtained by adding polyoxyethylene to polyethyleneimine as a dispersant. Next, ion-exchanged water, ethanol, and a surfactant were added to the obtained dispersion, thereby preparing a 5 mass% silver particle dispersion.

Preparation example 2: preparation of primer (B-1)

To the blocked isocyanate solution obtained in production example 1, 7 parts by mass of triethylamine was added at 40 ℃ to neutralize the carboxyl groups of the blocked isocyanate, water was added and the mixture was sufficiently stirred, and then methyl ethyl ketone was distilled off to obtain a resin composition for a primer layer containing blocked isocyanate and water, the nonvolatile component of which was 20% by mass. Subsequently, methyl ethyl ketone was added to the resin composition and diluted and mixed, whereby a primer (B-1) having a nonvolatile content of 2 mass% was obtained.

Preparation example 3: preparation of primer (B-2)

An epoxy resin (EPICLON HP-4032D manufactured by DIC Co., ltd.; naphthalene type epoxy resin, epoxy equivalent 140 g/equivalent, 2 functions) was diluted with methyl ethyl ketone to give a solid content of 2% by mass, and 4.57 parts by mass of a solution having a solid content of 2% by mass, obtained by diluting trimellitic anhydride with methyl ethyl ketone, was uniformly mixed with 100 parts by mass of the thus obtained solution to give a primer (B-2).

Preparation example 4: preparation of primer (B-3)

An epoxy resin (EPICLON HP-4700 manufactured by DIC Co., ltd.; naphthalene-type epoxy resin, epoxy equivalent 162 g/equivalent, 4 functions) was diluted with methyl ethyl ketone to give a solid content of 2 mass%, and 9.9 mass parts of a solution having a solid content of 2 mass% obtained by diluting trimellitic anhydride with methyl ethyl ketone was uniformly mixed with 100 mass parts of the thus-obtained solution to give a primer (B-3).

Preparation example 5: preparation of primer (B-4)

An epoxy resin (EPICLON HP-4700 manufactured by DIC Co., ltd.; naphthalene-type epoxy resin, epoxy equivalent 162 g/equivalent, 4 functions) was diluted with methyl ethyl ketone to give a solid content of 2 mass%, and to 100 parts by mass of the thus obtained solution, 4 parts by mass of a 2 mass% solid solution obtained by diluting 2-ethyl-4-imidazole (Curezol 2E4MZ manufactured by Siku Chemie Co., ltd.) with methyl ethyl ketone was uniformly mixed to give a primer (B-4).

Preparation example 6: preparation of primer (B-5)

An epoxy resin (EPICLON HP-4770 manufactured by DIC Co., ltd.; naphthalene-type epoxy resin, epoxy equivalent 204 g/equivalent, 2 functions) was diluted with methyl ethyl ketone to give a solid content of 2 mass%, and 15.7 mass parts of a solution having a solid content of 2 mass% obtained by diluting trimellitic anhydride with methyl ethyl ketone was uniformly mixed with 100 mass parts of the thus-obtained solution to give a primer (B-5).

Production example 1: preparation of Polyphenylene Sulfide (PPS) substrate

100 parts by mass of linear polyphenylene sulfide (MFR: 600g/10 min according to ASTM D1238-86), 58.8 parts by mass of chopped glass fiber (FT 562, fibrous inorganic filler, manufactured by Asahi Fiber Glass Co., ltd.), 8.4 parts by mass of ethylene-methacrylic acid copolymer zinc ion (Himilan 1855, manufactured by Sanyo DuPont chemical Co., ltd.) and 0.8 part by mass of montanic acid complex ester wax (Licolub WE40, manufactured by Crain Japan Co., ltd.) were uniformly mixed, and then melt-kneaded at 290 to 330℃using a twin-screw extruder of 35mm phi to obtain a polyphenylene sulfide resin composition. The obtained polyphenylene sulfide resin composition was molded by an injection molding machine, whereby a PPS substrate having dimensions of 50mm×105mm×2mm was produced.

[ evaluation of adhesion Strength of Metal coating layer formed on insulating substrate ]

For evaluation of adhesion strength of the metal plating layer formed on the insulating substrate, a metal plating film 15 μm thick was formed into a short stripe pattern with a width of 5mm, and 90 ° peeling was performed using "Bond test SS-30WD" manufactured by sierozem corporation, and converted to a strength of about 1cm, whereby evaluation was performed.

[ evaluation of insulation reliability of substrate after formation of Metal plating ]

A dry film resist was laminated on a copper plating layer formed on an insulating substrate, and after an etching resist pattern of L/s=200/200 μm was formed, a pattern was formed on the copper plating layer by a subtractive method using ferric chloride. After the substrate was cleaned, the copper-etched surface of the dried substrate was observed and analyzed for metal residues by a scanning electron microscope ("JSM-IT 500" manufactured by japan electronics corporation) and an energy dispersive X-ray analysis device (EDS). When no metal residue is found between the wiring patterns, the insulation reliability is judged to be acceptable (OK). When the metal residue is confirmed, the reliability is judged to be unqualified (NG).

Example 1

The ozone micro-nano bubble generating apparatus (manufactured by NACOO Co., ltd.) was used to prepare water containing ozone micro-nano bubbles, the concentration of ozone was confirmed to be 5ppm by a simple ozone water detector (DOC-05A manufactured by Equipped with common use, co., ltd.), and a polyimide film (Upilex 25SGA manufactured by Yu Xingxing Co., ltd.; thickness 25 μm) cut to a size of 19cm X25 cm was immersed in the water containing ozone nano bubbles for 15 minutes.

The silver particle dispersion obtained in preparation example 1 was applied to the surface of the polyimide film treated with water containing ozone nanobubbles by using a desktop small coater (K Printing Proofer manufactured by RK Print Coat Instruments Co.) so that the average thickness after drying was 30 nm. Subsequently, the polyimide film was dried at 200 ℃ for 5 minutes using a hot air dryer, thereby forming a silver particle layer (M1) on the surface of the polyimide film.

Next, the polyimide film having the silver particle layer formed thereon was immersed in an electroless copper plating solution ("circluposit 6550" manufactured by rombin electronic materials corporation) at 35 ℃ for 10 minutes, and an electroless copper plating film (thickness 0.2 μm) was formed on the surface of the silver particles. Further, an electroless Copper plating layer was provided on the cathode, and a phosphorus-containing Copper was used as the anode, and an electrolytic plating solution (60 g/L of Copper sulfate, 190g/L of sulfuric acid, 50mg/L of chloride ion, and additive (Copper stream ST-901 manufactured by Rogowski electronic materials Co., ltd.) containing Copper sulfate was used at a current density of 2A/dm ² Electrolytic plating was performed for 34 minutes, thereby forming a copper plating layer (M2) 15 μm thick.

Example 2

A silver particle layer (M1) was formed on the ozone micro-nano bubble water-treated polyimide film in the same manner as in example 1, except that the average thickness of the silver particle layer after drying was changed from 30nm to 80 nm. Next, a silver nanoparticle layer (M1) formed on a polyimide film was provided on a cathode, and a copper plating layer (M2) having a thickness of 15 μm was obtained in the same manner as in example 1.

Example 3, 4

In examples 1 and 2, copper plating (M2) having a thickness of 15 μm was obtained on the silver particle layer (M1) formed on the polyimide film in the same manner as in examples 1 and 2, except that the ozone concentration of the ozone micro-nano bubble water was changed from 5ppm to 2.5ppm and the immersion treatment time of the polyimide film was changed from 15 minutes to 40 minutes.

Example 5

In the same manner as in example 1, the primer (B-1) obtained in production example 1 was applied to the surface of the polyimide film treated with water containing ozone micro-nano bubbles by using a desktop small coater (KPrinting Proofer manufactured by RK Print Coat Instruments Co.) so that the thickness after drying was 100 nm. Next, the polyimide film was dried at 120 ℃ for 5 minutes using a hot air dryer, thereby forming a primer layer (B) on the surface of the polyimide film.

The silver particle dispersion obtained in preparation example 1 was applied to the surface of the polyimide film treated with water containing ozone nanobubbles by using a desktop small coater (K Printing Proofer manufactured by RK Print Coat Instruments Co.) so that the average thickness after drying was 80 nm. Subsequently, the polyimide film was dried at 200 ℃ for 5 minutes using a hot air dryer, thereby forming a silver particle layer (M1) on the surface of the polyimide film.

After the silver particle layer (M1) was formed, electroless copper plating and electrolytic copper plating were performed in the same manner as in example 1, and a copper plating layer (M2) having a thickness of 15 μm was obtained on the silver particle layer (M1).

Example 6

In example 5, in the same manner as in example 2, electrolytic copper plating was directly performed using the silver particle layer (M1) as a cathode, instead of performing electroless copper plating and electrolytic copper plating on the silver particle layer (M1), thereby obtaining a copper plating layer (M2) 15 μm thick on the silver particle layer (M1).

Example 7

In example 5, electroless nickel-boron (TOPCHEM ALLOY 66-LF, manufactured by Aofield pharmaceutical industries Co., ltd.) was used instead of electroless copper plating, and a nickel-boron layer having a film thickness of 0.2 μm was formed on the silver particle layer (M1) at 65℃for 2 minutes, and electrolytic copper plating was performed in the same manner as in example 5, thereby obtaining a metal plating layer (M2) composed of nickel-boron and copper plating.

Example 8

In example 6, electrolytic nickel plating was carried out using an electrolytic nickel plating solution (sulfamic acid bath: sulfamic acid nickel tetrahydrate 350g/L, nickel chloride hexahydrate 5g/L, boric acid 60 g/L) instead of carrying out electrolytic copper plating at 8A/dm at 60 DEG C ² Plating was performed for 8 minutes and 40 seconds, whereby a nickel plating layer (M2) 15 μm thick was obtained on the silver particle layer (M1).

Example 9

The ozone micro-nano bubble generating device (manufactured by NACOO Co., ltd.) was used to prepare water containing ozone micro-nano bubbles, and a simple ozone water detector (DOC-05A manufactured by Emotion Co., ltd.) was used to confirm that the ozone concentration was 5ppm. Next, the PPS molding substrate produced in production example 1 was immersed in water containing ozone micro-nano bubbles for 15 minutes, and then dried.

The PPS substrate thus treated with water containing ozone micro-nano bubbles was immersed in the primer (B-1) obtained in preparation example 2 for 10 seconds and dried, and then fired at 200℃for 5 minutes, to obtain a 120nm thick primer layer (B). Next, the PPS substrate having the primer layer formed on the surface was immersed in the silver particle dispersion liquid obtained in preparation example 1 for 10 seconds, dried, and then baked at 200 ℃ for 30 minutes. The film thickness of the silver particle layer (M1) obtained was 100nm.

The PPS substrate thus formed with the silver particle layer (M1) was subjected to electroless copper plating and electrolytic copper plating treatment in the same manner as in example 1, whereby a copper plating layer (M2) having a thickness of 15 μm was obtained on the PPS substrate.

Example 10

In example 9, in the same manner as in example 2, electrolytic copper plating was directly performed using the silver particle layer (M1) as a cathode, instead of performing electroless copper plating and electrolytic copper plating on the silver particle layer (M1), thereby obtaining a copper plating layer (M2) 15 μm thick on the primer layer/silver particle layer (M1) formed on the PPS substrate.

Examples 11 to 20

A metal plating layer (M2) was obtained on a PPS substrate in the same manner as in examples 9 and 10, except that the types of the primer used in the primer layer, the plating step, and the metal plating layer (M2) were changed as shown in table 1.

Example 21

In example 10, in the same manner as in example 10 except that the PPS substrate was treated by immersing in ozone water having an ozone concentration of 10ppm produced by using an oxygen generator-ozone generator-dissolved ozone concentration meter-dissolution tank line manufactured by the common use of NACOO, instead of immersing in ozone micro-nano bubbles-containing water produced by using an ozone micro-nano bubble generating device (manufactured by common use of NACOO), for 15 minutes, a copper plating layer (M2) having a thickness of 15 μm was obtained on the primer layer/silver particle layer (M1) formed on the PPS substrate.

Example 22

The surface of the PPS molded substrate obtained in preparation example 1 was irradiated with light of 172nm for 5 minutes under a nitrogen stream containing oxygen at a partial pressure of 0.5% by using an excimer light irradiation apparatus (UER 20-172 type manufactured by USHIO Motor Co., ltd.) and treated in an ozone atmosphere. After the surface of the PPS substrate was treated under an ozone atmosphere, a copper plating layer (M2) having a thickness of 15 μm was obtained on the primer layer/silver particle layer (M1) formed on the PPS substrate in the same manner as in example 10.

Comparative example 1

In example 1, a silver particle layer (M1)/15 μm thick copper plating layer was formed on the polyimide film surface in the same manner as in example 1, except that the polyimide film was not treated with water containing ozone micro-nano bubbles.

Comparative example 2

In example 2, a silver particle layer (M1)/15 μm thick copper plating layer was formed on the polyimide film surface in the same manner as in example 2, except that the polyimide film was not treated with water containing ozone micro-nano bubbles.

Comparative example 3

In example 9, a silver particle layer (M1)/15 μm thick copper plating layer was formed on the surface of a PPS molding substrate in the same manner as in example 9, except that the PPS molding substrate was not treated with water containing ozone micro-nano bubbles.

Comparative example 4

In example 10, a silver particle layer (M1)/15 μm thick copper plating layer was formed on the surface of a PPS molding substrate in the same manner as in example 10, except that the PPS molding substrate was not treated with water containing ozone micro-nano bubbles.

Comparative example 5

The polyimide film was treated with water containing ozone micro-nano bubbles at an ozone concentration of 5ppm for 15 minutes in the same manner as in example 1. The plating treatment on the polyimide film is performed based on literature ("related study of surface modification of various resins and functional plating film formation techniques", doctor's article at university of kanto, month 1 in 2014, west village, unfortunately, p.48). The polyimide film treated in the ozone-plated atmosphere was immersed in an aqueous alkali solution (sodium hydroxide 50 g/L) set at 65℃for 2 minutes, and subjected to a conditioning agent treatment (CC 231 conditioning agent manufactured by Rogowski electronics Co., ltd.) at 45℃for 2 minutes. Then, the catalyst was immersed in an aqueous solution (30 g/L) of sodium phosphinate at 45℃for 1 minute through a catalytic step of immersing the catalyst in an aqueous solution (0.3 g/L) of palladium chloride at 45℃for 2 minutes, thereby activating the palladium catalyst.

Using an electroless copper-nickel-phosphorus plating solution (Na ₃ (C ₃ H ₅ O(COO) ₃ )15g/L、CuSO ₄ ·5H ₂ O 7g/L、NiSO ₄ ·6H ₂ O 3g/L、H ₃ BO ₃ 15g/L、NaH ₂ PO ₂ ·H ₂ O19.4 g/L, pH 8) the polyimide film subjected to palladium catalyst activation was treated, thereby forming a copper-nickel-phosphorus plating film of 0.2 μm thickness. After annealing the film at 120℃for 1 hour, dilute sulfuric acid (H) ₂ SO ₄ 1 vol%) was immersed for 30 seconds, and electrolytic copper plating was performed, thereby forming a copper plating layer 15 μm thick.

Comparative example 6

In comparative example 5, in the same manner as in comparative example 5 except that the insulating substrate (A) used was changed to the PPS molded article produced in production example 1, and the time of immersion treatment in water containing ozone micro-nano bubbles was changed from 15 minutes to 60 minutes, an electroless copper-nickel-phosphorus/15 μm thick copper-plated metal layer was formed on the surface of the PPS molded substrate, in an amount of 0.2 μm.

The production conditions, peel strength (kN/m), and inter-line metal removability of examples 1 to 22 and comparative examples 1 to 6 are shown in tables 1 and 2. In comparative examples 5 and 6, electroless copper plating, nickel plating, and electrolytic copper plating were performed, but since a penetration layer was formed on the surface of the substrate, residues of plated metal were confirmed on the surface after patterning in the above-mentioned [ evaluation of insulation reliability of the substrate after formation of the metal plating layer ].

TABLE 1

TABLE 2

Claims

1. A method for forming a metal film, characterized by comprising:

step 1, treating an insulating substrate (A) in an ozone atmosphere;

2. A method for forming a metal film, characterized by comprising:

step 1, treating an insulating substrate (A) in an ozone atmosphere;

3. The method of forming a metal film according to claim 1 or 2, wherein the metal particles in the metal particle layer (M1) are 1 or more selected from the group consisting of at least silver, copper, nickel, gold, and platinum.

4. The method for forming a metal film according to claim 2 or 3, wherein the primer layer (B) uses a resin having a reactive functional group [ X ], and the polymer dispersant uses a dispersant having a reactive functional group [ Y ] to form a bond between the reactive functional group [ X ] and the reactive functional group [ Y ].

6. The method for forming a metal film according to claim 5, wherein the polymer dispersant having the reactive functional group [ Y ] is 1 or more selected from the group consisting of polyalkyleneimines and polyalkyleneimines having a polyoxyalkylene structure containing an oxyethylene unit.

8. The method according to any one of claims 1 to 7, wherein the step 1 of treating the insulating substrate (a) in an ozone atmosphere is a step of bringing the insulating substrate (a) into contact with an aqueous solution containing ozone.

9. The method according to any one of claims 1 to 7, wherein the step 1 of treating the insulating substrate (a) in an ozone atmosphere is a step of bringing the insulating substrate (a) into contact with an ozone-containing gas.

10. The method of forming a metal film according to claim 9, wherein the step of bringing the insulating substrate (a) into contact with the ozone-containing gas is performed by irradiating Ultraviolet (UV) light onto the insulating substrate (a) in an atmosphere containing oxygen.