Semi-additive method using a laminate and printed wiring board using the same

Abstract

This invention provides a semi-additive laminate for forming a multilayer printed wiring board by electrically connecting it to the conductor circuit layer of an inner printed wiring substrate, and a printed wiring board using the same. This semi-additive laminate exhibits high adhesion between the substrate and the conductor circuit, enabling the formation of wiring with minimal undercut, excellent design reproducibility, and a favorable rectangular cross-sectional shape for circuit wiring. It was discovered that by sequentially stacking a conductive silver particle layer (M1) and a copper layer (M2) on both surfaces of an insulating substrate (A), with the copper layer (M2) having a thickness of 0.1 μm to 2 μm, high adhesion between the substrate and the conductor circuit is achieved, enabling the formation of a printed wiring board with minimal undercut, excellent design reproducibility, and a favorable rectangular cross-sectional shape for circuit wiring, electrically connecting the conductor circuit layer of the inner printed wiring substrate. This invention is thus completed.

Description

Technical Field

[0001] The present invention relates to a planar semi-additive laminate for electrically connecting two sides of a substrate and a printed wiring board using the same. Background Technology

[0002] Printed wiring boards (PCBs) are metal layers with circuit patterns formed on the surface of an insulating substrate. In recent years, with the miniaturization and weight reduction requirements of electronic devices, there is a need for thinner PCBs (films) and more precise circuit wiring. Previously, a subtractive method was widely used to manufacture circuit wiring: etching resists that form circuit patterns on the surface of a copper layer on an insulating substrate were used, and the copper layers in areas where no circuitry was required were etched to form copper wiring. However, in this subtractive method, copper residue at the bottom edge of the wiring is prone to remain. If the wiring density is increased, leading to shorter distances between wirings, problems such as short circuits and insufficient insulation reliability between wirings can occur. Furthermore, if further etching is performed to prevent short circuits and improve insulation reliability, the etching solution can spread into the lower part of the resist, advancing lateral etching and resulting in a thinner wiring width. Especially when areas with different wiring densities are mixed together, fine wiring in areas with low wiring density may disappear if etched. Furthermore, the cross-sectional shape of the wiring obtained by the subtractive method is not rectangular, but becomes a trapezoidal or triangular shape with the bottom edge extending towards the substrate. Therefore, it becomes a wiring with a different width in the thickness direction, which also presents a challenge as an electrical transmission path.

[0003] A semi-additive method has been proposed as a way to fabricate micro-wiring circuits to solve these problems. In the semi-additive method, a conductive seed layer is first formed on an insulating substrate, and then a resist is plated onto the non-circuit-forming portion of the seed layer. After the wiring portion is formed by electroplating through the conductive seed layer, the resist is peeled off, and the seed layer of the non-circuit-forming portion is removed, thereby forming a micro-wiring circuit. According to this method, since the plating is deposited along the shape of the resist, the cross-sectional shape of the wiring can be rectangular. Furthermore, since the wiring of the target width can be deposited regardless of the density of the pattern, it is suitable for the formation of micro-wiring circuits.

[0004] In semi-addition processes, methods for forming conductive seed layers on insulating substrates using electroless copper plating or electroless nickel plating with palladium catalysts are known. In these methods, for example, when using build-up films, to ensure adhesion between the film substrate and the copper plating film, a surface roughening process called desmearing roughening is performed using a strong reagent such as permanganate. The plating film forms from the resulting voids, thereby utilizing an anchoring effect to ensure adhesion between the insulating substrate and the plating film. However, if the substrate surface is roughened, issues arise such as difficulty in forming fine wiring and degradation of high-frequency transmission characteristics. Therefore, reducing the degree of roughening has been studied; however, with low roughening, the required adhesion strength between the formed wiring and the substrate cannot be obtained.

[0005] On the other hand, techniques for forming conductive seed crystals by electroless nickel plating on polyimide films are also known. In this case, the polyimide film is immersed in a strong alkali, thereby opening the ring-shaped imide rings on the surface and making the film surface hydrophilic, while simultaneously forming a water-permeable modified layer. A palladium catalyst is then permeated into this modified layer, and electroless nickel plating is performed, thereby forming a nickel seed layer (for example, see Patent Document 1). In this technique, nickel plating is formed from the outermost modified layer of the polyimide to obtain adhesion strength, but since this modified layer is in a state of open imide rings, there is a problem that the film surface becomes a physically and chemically fragile structure.

[0006] In contrast, as a method that does not involve surface roughening or forming a modified layer on the surface, it is also known to form conductive seed crystals such as nickel or titanium on an insulating substrate by sputtering (for example, see Patent Document 2). This method can form a seed layer without roughening the substrate surface, but it has the following problems: it requires expensive vacuum equipment, requires a large initial investment, the size and shape of the substrate are limited, the productivity is low, and the process is cumbersome.

[0007] As a solution to the problems of sputtering methods, a method has been proposed that utilizes a coating layer of conductive ink containing metal particles as a conductive seed layer (for example, see Patent Document 3). This technology discloses a method of coating a conductive ink containing metal particles with a particle size of 1 to 500 nm onto an insulating substrate made of a film or sheet, subjecting it to heat treatment, thereby fixing the metal particles in the coated conductive ink as a metal layer onto the insulating substrate to form a conductive seed layer, and then performing plating on this conductive seed layer.

[0008] Patent document 3 proposes a pattern formation method using a semi-additive process. In the embodiments, it describes using a substrate with a copper conductive seed layer formed by coating conductive ink containing dispersed copper particles and heat-treating it as the substrate for the semi-additive process. A photosensitive resist is formed on the conductive seed layer. After exposure and development, the pattern formation area is thickened using electrolytic copper plating. After the resist is removed, the copper conductive seed layer is etched away. Furthermore, in the ongoing research on forming printed circuit boards using a semi-additive process, a substrate with a thin copper foil or copper-plated film as conductive seed crystals on an insulating substrate is used as the substrate for the semi-additive process.

[0009] Thus, it is known that when the conductive seed layer and the conductive layer of the circuit pattern are formed of the same metal, such as in the combination of a copper conductive seed layer and a copper circuit pattern, the conductive layer of the circuit pattern is also etched when the conductive seed layer of the non-patterned part is removed. As a result, the circuit pattern becomes thinner and finer, and the surface roughness of the circuit conductive layer also increases. This is a problem that should be solved when manufacturing high-density wiring and high-frequency transmission wiring.

[0010] Regarding these issues, the inventors have invented a technique in which a substrate with a conductive silver particle layer formed on the surface of an insulating substrate is used as the substrate for the semi-additive method. This prevents the circuit pattern from becoming thinner or thinner during the seed layer etching process, resulting in a printed wiring board with excellent design reproducibility and a smooth circuit layer surface. (Non-Patent Literature 1, 2)

[0011] This technology can not only form circuits on one side, but also connect circuits on both sides, or multiply them and connect them to the conductor circuit layer of the inner printed wiring substrate. However, in the case of forming holes in the substrate to form holes for two-sided connection in order to connect two sides or to the conductor circuit layer of the inner layer, if the two-sided electrical connection process using the conventional direct plating method is performed, the conductive silver particle layer will be damaged and its conductivity will be reduced in the micro-etching process to remove conductive substances such as palladium, conductive polymer, and carbon adsorbed on the conductive seed layer. Therefore, it is sometimes difficult to use it as a conductive seed layer for forming circuit patterns.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: International Publication No. 2009 / 004774;

[0015] Patent Document 2: Japanese Patent Application Publication No. 9-136378;

[0016] Patent document 3: Japanese Patent Application Publication No. 2010-272837;

[0017] Non-patent literature 1: Akira Murakawa, Norimasa Fukasawa, Wataru Fujikawa, Jun Shiraha: "Copper patterning technique using a semi-additive method based on silver nanoparticles", Proceedings of the 28th Symposium on Microelectronics, pp. 285-288, 2018.

[0018] Non-Patent Literature 2: Akira Murakawa, Shota Shinbayashi, Norimasa Fukasawa, Wataru Fujikawa, Jun Shiraha: “Copper Wiring Formation Using a Semi-Additive Method with Silver as Seed Layer”, Proceedings of the 33rd Spring Conference of the Institute of Electronics and Equipment, 11B2-03, 2019. Summary of the Invention

[0019] The problem that the invention aims to solve

[0020] The problem to be solved by the present invention is to provide a semi-additive laminate for forming a multilayer printed wiring board by electrically connecting it to the conductor circuit layer of the inner printed wiring substrate, and a printed wiring board using the same. The semi-additive laminate does not require surface roughening with chromic acid or permanganate, does not require the formation of a surface modification layer with alkali, does not use a vacuum device, has high adhesion between the substrate and the conductor circuit, and can form wiring with less undercut, good design reproducibility, and a good rectangular cross-sectional shape as circuit wiring.

[0021] Methods for solving problems

[0022] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by using a laminate in which a conductive silver particle layer (M1) and a copper layer (M2) are sequentially stacked on both surfaces of an insulating substrate (A), and the thickness of the copper layer (M2) is 0.1 μm to 2 μm, it is possible to achieve high adhesion between the substrate and the conductor circuit without complex surface roughening, without the formation of a surface modification layer, and without the use of a vacuum device. This results in a printed wiring board with low undercut, good design reproducibility, and a good rectangular cross-sectional shape for circuit wiring, which is electrically connected to the conductor circuit layer of the inner printed wiring substrate. Thus, the present invention was completed.

[0023] That is, the present invention provides the following:

[0024] 1. A semi-additive laminate, characterized in that it is a semi-additive laminate used for manufacturing multilayer printed wiring boards for electrically connecting a conductive circuit layer (CM1) on the surface of a substrate to a conductor circuit layer (CM2) on an inner printed wiring substrate.

[0025] A conductive silver particle layer (M1) and a copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, and the thickness of the copper layer (M2) is 0.1 μm to 2 μm. The inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0026] 2. The semi-additive laminate as described in 1, characterized in that a primer layer (B) is further provided between the surface (S1) of the insulating layer (A) and the conductive silver particle layer (M1).

[0027] 3. A semi-additive laminate, characterized in that it is a semi-additive laminate used for manufacturing multilayer printed wiring boards for electrically connecting a conductive circuit layer (CM1) on the surface of a substrate to a conductive circuit layer (CM2) on an inner printed wiring substrate.

[0028] A conductive silver particle layer (M1) is formed on the surface of the insulating layer (A) stacked on the inner printed wiring substrate, wherein a conductive circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate.

[0029] Furthermore, it has holes extending from the insulating layer (A) to the conductor circuit layer (CM2).

[0030] The surface of the aforementioned pores is a substrate whose conductivity is ensured by any one of palladium, conductive polymer, or carbon.

[0031] 4. The semi-additive laminate as described in 3, characterized in that a primer layer (B) is further provided between the insulating layer (A) and the conductive silver particle layer (M1).

[0032] 5. The semi-addition laminate as described in any one of 1 to 4, wherein the silver particles constituting the silver particle layer (M1) are coated with a polymeric dispersant.

[0033] 6. A laminate for use in a semi-addition process as described in 2 or 4, wherein the primer layer (B) described in 2 and 4 is a layer composed of a resin having a reactive functional group [X], and the polymeric dispersant has a reactive functional group [Y], wherein the reactive functional group [X] and the reactive functional group [Y] can form bonds with each other through a reaction.

[0034] 7. The semi-addition method using a laminate as described in 6, wherein the reactive functional group [Y] is a basic nitrogen atom group.

[0035] 8. The laminate for the semi-addition process as described in 6, wherein the polymeric dispersant having the above-mentioned reactive functional group [Y] is selected from one or more polyalkylene imides and polyalkylene imides having a polyoxyethylene unit polyoxyalkylene structure.

[0036] 9. The laminate used in the semi-addition process as described in 6, wherein the reactive functional group [X] is selected from one or more of the group consisting of ketone, acetoacetyl, epoxy, carboxyl, N-alkanol, isocyanate, vinyl, (meth)acryloyl, and allyl.

[0037] 10. A printed wiring board, characterized in that it is formed by a laminate using any one of the semi-additive methods described in any one of 1 to 9.

[0038] 11. A multilayer printed wiring board, characterized in that it is a multilayer printed wiring board formed by electrically connecting a conductive circuit layer (CM1) on the surface of a substrate and a conductive circuit layer (CM2) on an inner printed wiring substrate.

[0039] A conductive silver particle layer (M1) and a copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, wherein the copper layer (M2) has a thickness of 0.1 μm to 2 μm, and a conductor circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate.

[0040] Furthermore, it has holes extending from the insulating layer (A) to the conductor circuit layer (CM2).

[0041] The surface of the aforementioned hole has a structure in which a conductor circuit layer (CM2) of palladium, conductive polymer, carbon, and copper is stacked and connected to the inner printed wiring substrate.

[0042] 12. The printed wiring board as described in 11, characterized in that a primer layer (B) is further provided between the insulating layer (A) and the silver particle layer (M1).

[0043] 13. A method for manufacturing a semi-additive laminate, used to manufacture a multilayer printed circuit board as described in any one of 3 to 9, characterized in that it comprises:

[0044] Step 1: A hole is formed in the laminate from the insulating layer (A) to the conductor circuit layer (CM2). The laminate has a conductive silver particle layer (M1) and a copper layer (M2) sequentially stacked on the surface of the insulating layer (A) stacked on the inner layer printed wiring substrate. The thickness of the copper layer (M2) is 0.1 μm to 2 μm. The conductor circuit layer (CM2) is formed on the insulating material in the inner layer printed wiring substrate.

[0045] Step 2: Apply palladium, a conductive polymer, or carbon to the surface of a substrate having a hole from the insulating layer (A) to the conductor circuit layer (CM2) to make the hole surface conductive.

[0046] Step 3 involves etching the copper layer (M2) to expose the conductive silver particle layer (M1).

[0047] 14. The method for manufacturing a semi-additive laminate as described in 13, characterized in that a primer layer (B) is further laminated between the insulating substrate (A) and the silver particle layer (M1).

[0048] 15. A method for manufacturing a multilayer printed circuit board as described in 10, characterized in that it comprises:

[0049] Step 1: A hole is formed in the laminate from the insulating layer (A) to the conductor circuit layer (CM2). The laminate has a conductive silver particle layer (M1) and a copper layer (M2) sequentially stacked on the surface of the insulating layer (A) stacked on the inner layer printed wiring substrate. The thickness of the copper layer (M2) is 0.1 μm to 2 μm. The conductor circuit layer (CM2) is formed on the insulating material in the inner layer printed wiring substrate.

[0050] Step 2: Apply palladium, a conductive polymer, or carbon to the surface of a substrate having a hole from the insulating layer (A) to the conductor circuit layer (CM2) to make the hole surface conductive.

[0051] Step 3 involves etching the copper layer (M2) to expose the conductive silver particle layer (M1).

[0052] Step 4: A patterned resist is formed on the conductive silver particle layer (M1).

[0053] Step 5 involves electrolytically plating copper to electrically connect the surface and inner conductor circuit layers (CM2) and forming the circuit pattern.

[0054] Step 6: The pattern resist is stripped off, and the silver particle layer (M1) of the non-conductor circuit pattern formation part is removed using an etching solution.

[0055] 16. The printed wiring board as described in 10, characterized in that a primer layer (B) is further provided between the insulating substrate (A) and the silver particle layer (M1).

[0056] Invention Effects

[0057] By using the semi-additive laminate of the present invention, printed circuit boards (PCBs) electrically connected to the conductor circuit layers of the inner PCB substrate can be designed and manufactured with good reproducibility without the use of vacuum equipment. These PCBs feature high adhesion to various smooth substrates, smooth surfaces, and good rectangular cross-sectional shapes. Therefore, by using the technology of the present invention, PCBs capable of handling high-density, high-performance, and high-frequency transmission in multilayered applications can be provided at low cost, making them highly industrially applicable in the PCB field. Furthermore, PCBs manufactured using the semi-additive laminate of the present invention can be used not only for conventional PCBs but also for various electronic components with patterned metal layers on the substrate surface. For example, they can be applied to connectors, electromagnetic shielding, RFID antennas, and thin-film capacitors. Attached Figure Description

[0058] [ Figure 1 ] Figure 1 This is a schematic diagram of the laminated body used in the semi-additive method according to claim 1.

[0059] [ Figure 2 ] Figure 2 Is Figure 1 A schematic diagram of the semi-addition laminate of claim 2, which has a primer layer on a silver particle layer.

[0060] [ Figure 3 ] Figure 3 This is a schematic diagram of the laminated body used in the semi-additive method as described in claim 3.

[0061] [ Figure 4 ] Figure 4 Is Figure 2 A schematic diagram of the semi-addition laminate of claim 4, which has a primer layer on a silver particle layer.

[0062] [ Figure 5 ] Figure 5 Is using Figure 1 The diagram shows the process of manufacturing printed wiring boards using a semi-additive method with laminates.

[0063] [ Figure 6 ] Figure 6 This is a schematic diagram of the comb-shaped electrode and pad pattern fabricated in Example 1.

[0064] [ Figure 7 ] Figure 7 These are schematic diagrams of the inner and outer layer circuit patterns in the printed wiring boards produced in Examples 22 to 26. Detailed Implementation

[0065] The semi-additive laminate of the present invention is characterized in that a conductive silver particle layer (M1) and a copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, and the thickness of the copper layer (M2) is 0.1 μm to 2 μm, wherein a conductor circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate.

[0066] Furthermore, a more preferred embodiment of the semi-additive laminate of the present invention is characterized by having a primer layer (B) between the insulating layer (A) and the conductive silver particle layer (M1).

[0067] In the semi-additive laminate of the present invention, a conductive silver particle layer (M1) and a copper layer (M2) are sequentially laminated on the surface of the insulating layer (A) laminated on the inner printed wiring substrate. The inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material. However, the insulating layer (A), the conductive silver particle layer (M1), and the copper layer (M2) can be formed on one side of the inner printed wiring substrate or laminated on both sides.

[0068] Materials used as the aforementioned insulating layer (A) include, for example: polyimide resin, polyamide-imide resin, polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polycarbonate resin, acrylonitrile-butadiene-styrene (ABS) resin, polyarylate resin, polyacetal resin, acrylic resins such as poly(meth)acrylate, polyvinylidene fluoride resin, polytetrafluoroethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, vinyl chloride resin grafted with acrylic resin, polyvinyl alcohol resin, polyethylene resin, polypropylene resin, urethane resin, cycloolefin resin, polystyrene, liquid crystal polymer (LCP), polyetheretherketone (PEEK) resin, polyphenylene sulfide (PPS), polyphenylene sulfone (PPSU), cellulose nanofibers, silicon, silicon carbide, gallium nitride, sapphire, ceramics, glass, diamond-like carbon (DLC), alumina, etc.

[0069] Furthermore, as the aforementioned insulating layer (A), a resin substrate containing a thermosetting resin and an inorganic filler can also be suitably used. Examples of the aforementioned thermosetting resin include, for instance, epoxy resin, phenolic resin, unsaturated imide resin, cyanate ester resin, isocyanate ester resin, and benzo[a]benzene[b]. Examples of suitable inorganic fillers include azircon resins, oxetine resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins. Conversely, examples of inorganic fillers include silica, alumina, talc, mica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, aluminum borate, and borosilicate glass. One or more of these thermosetting resins and inorganic fillers can be used.

[0070] As the form of the above-mentioned insulating layer (A), commercially available materials molded into films, sheets, or plates can be used, or materials obtained by molding the above-mentioned resin solution, melt, or dispersion into a planar shape can be used. Alternatively, the above-mentioned insulating layer (A) can be made by coating the above-mentioned resin solution, melt, or dispersion onto a printed wiring substrate on which a conductor circuit layer (CM2) is formed.

[0071] The aforementioned insulating layer (A) can be used as a single layer or in multiple layers. In the case of multiple layers, a single material can be layered, or different materials can be layered in multiple layers.

[0072] The aforementioned insulating layer (A) can be directly laminated onto a printed wiring substrate on which the conductor circuit layer (CM2) is formed, or it can be laminated via an adhesive layer. As for the adhesive layer, it can be used without particular restriction as long as it has insulating properties; commercially available materials as adhesive sheets or interlayer adhesive sheets can be used appropriately. When using the aforementioned insulating adhesive layer, it is equivalent to the case of laminating multiple layers of different materials, allowing the entire laminated insulating material to be used as the aforementioned insulating layer (A).

[0073] When using the above-mentioned commercially available adhesive sheet or interlayer adhesive sheet as the adhesive layer and laminating the above-mentioned insulating layer (A) on the inner printed wiring substrate on which the conductor circuit layer (CM2) is formed, the lamination can be performed under the steps and heating and pressurizing conditions described in the product catalog, instruction manual, user manual, etc.

[0074] The inner layer printed wiring substrate with conductor circuit layer (CM2) formed in the present invention can be selected as appropriate, either as a rigid substrate or a flexible substrate, and various commercially available substrates with circuit patterns formed in the copper foil of copper clad laminate materials can be used.

[0075] When a printed wiring board is manufactured using the laminate of the present invention, the silver particle layer (M1) becomes the plating substrate layer when the conductive circuit layer (CM1) as the wiring pattern is formed by the plating process.

[0076] The silver particles constituting the silver particle layer (M1) may contain metal particles other than silver within the range that allow the plating process described later to be carried out without problems. However, in order to further improve the etching removeability of the non-circuit forming part described later, the proportion of metal particles other than silver is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, relative to 100 parts by mass of silver.

[0077] As a method for forming the silver particle layer (M1) on both sides of the planar insulating layer (A), for example, a method of coating both sides of the insulating layer (A) with a silver particle dispersion can be listed. There are no particular limitations on the coating method of the silver particle dispersion, as long as the silver particle layer (M1) can be formed well. Various coating methods can be appropriately selected according to the shape, size, rigidity, and flexibility of the insulating layer (A) used. Specific coating methods include, for example: gravure printing, offset printing, flexographic printing, pad printing, gravure offset printing, letterpress printing, letterpress reversal printing, screen printing, micro-touch printing, reverse printing, pneumatic doctor blade coating, blade coating, air knife coating, extrusion coating, impregnation coating, transfer roller coating, contact coating, cast coating, spray coating, inkjet printing, die coating, spin coating, rod coating, dip coating, etc. At this time, the silver particle layer (M1) can be formed on both sides of the insulating layer (A) at the same time, or it can be formed on one side of the insulating layer (A) and then on the other side.

[0078] To improve the coatability of the silver particle dispersion and enhance the adhesion to the substrate of the conductive circuit layer (CM1) formed during the plating process, the insulating layer (A) and the primer layer (B) formed on the insulating layer (A) can be surface-treated before coating with the silver particle dispersion. There are no particular limitations on the surface treatment method for the insulating layer (A), as long as the surface roughness increases and the formation of micro-pitch patterns and signal transmission loss caused by the rough surface are not problematic; various methods can be appropriately selected. Examples of such surface treatment methods include: UV treatment, gas-phase ozone treatment, liquid-phase ozone treatment, corona treatment, and plasma treatment. These surface treatment methods can be performed using one method or in combination of two or more methods.

[0079] After the above-mentioned silver particle dispersion is applied to the above-mentioned insulating layer (A) or the above-mentioned primer layer (B), the coating film is dried, thereby causing the solvent contained in the silver particle dispersion to evaporate, and the above-mentioned silver particle layer (M1) is formed on the above-mentioned insulating layer (A) or the above-mentioned primer layer (B).

[0080] The drying temperature and time described above can be appropriately selected based on the heat resistance temperature of the substrate used and the type of solvent used in the metal particle dispersion (described later). A range of 20–350°C is preferred, and the time is preferably in the range of 1–200 minutes. Furthermore, in order to form a silver particle layer (M1) with excellent adhesion on the substrate, a drying temperature in the range of 0–250°C is more preferable.

[0081] The insulating layer (A) that forms the silver particle layer (M1) or the insulating layer (A) that forms the primer layer (B) can be further annealed after drying, as needed, to reduce the resistance of the silver particle layer and improve the adhesion between the insulating layer (A) or the primer layer (B) and the silver particle layer (M1). The annealing temperature and time can be appropriately selected according to the heat resistance temperature of the substrate used, the required resistance, the productivity, etc., and can be carried out for 1 minute to 2 weeks in the range of 60 to 350°C. In addition, it is preferable to carry out the annealing for 1 minute to 2 weeks in the temperature range of 60 to 180°C, and preferably to carry it for about 1 minute to 5 hours in the temperature range of 180 to 350°C.

[0082] Regarding the aforementioned drying process, air supply may or may not be required. Furthermore, drying can be carried out in the atmosphere, under a displacement atmosphere of inert gases such as nitrogen or argon, or under a gas flow, or even in a vacuum.

[0083] In addition to natural drying at the coating site, the coated film can also be dried in a dryer such as a blower or a constant-temperature dryer. Furthermore, when the aforementioned insulating layer (A) is a roll film or sheet, the roll material can be continuously moved within a designated non-heated or heated space after the coating process, thereby performing drying and firing. Examples of heating methods for this drying and firing process include ovens, hot air drying furnaces, infrared drying furnaces, laser irradiation, microwaves, and light irradiation (flash irradiation devices). One or more of these heating methods can be used.

[0084] The amount of the metal particle layer (M1) formed on the insulating layer (A) or the primer layer (B) is preferably 0.01 to 30 g / m. 2 The range is more preferably 0.01–10 g / m 2 The range is specified. Furthermore, considering the ease of forming the conductive circuit layer (CM1) through the plating process described later and the ease of removing the seed layer through the etching process described later, a concentration of 0.05–5 g / m is further preferred. 2 The range.

[0085] The amount of silver particle layer (M1) formed can be confirmed using well-known analytical methods such as fluorescence X-ray diffraction, atomic absorption spectrometry, and ICP.

[0086] Furthermore, in the process of exposing the circuit pattern to the resist layer using active light, in order to suppress the reflection of active light from the silver particle layer (M1), the silver particle layer (M1) may contain light-absorbing pigments or dyes such as graphite or carbon, anthocyanin compounds, phthalocyanine compounds, dithiols, naphthoquinone compounds, diimide compounds, and azo compounds as light absorbers, within a range that allows the formation of the silver particle layer (M1), enables the normal implementation of the electrolytic plating process described later, and ensures the etch removeability described later. These pigments or dyes can be appropriately selected according to the wavelength of the active light used. Furthermore, one or more of these pigments or dyes may be used. Moreover, to include these pigments or dyes in the silver particle layer (M1), these pigments or dyes can be added to the silver particle dispersion described later.

[0087] The silver particle dispersion used to form the silver particle layer (M1) is formed by dispersing silver particles in a solvent. There are no particular limitations on the shape of the silver particles, as long as the silver particle layer (M1) is formed well; various shapes of silver particles, such as spherical, lenticular, polyhedral, plate-like, rod-like, and linear, can be used. These silver particles can be of a single shape or a combination of two or more different shapes.

[0088] When the silver particles are spherical or polyhedral in shape, their average particle size is preferably in the range of 1 to 20,000 nm. Furthermore, when forming fine circuit patterns, considering the ability to further improve the homogeneity of the silver particle layer (M1) and the removability using the etching solution (described later), the average particle size is more preferably in the range of 1 to 200 nm, and even more preferably in the range of 1 to 50 nm. It should be noted that the "average particle size" of the nano-sized particles is the volume average value measured by dynamic light scattering method after diluting the metal particles with a good dispersing solvent. In this measurement, "Nanotrac UPA-150" manufactured by MICROTRAC can be used.

[0089] On the other hand, when the silver particles have shapes such as lens-shaped, rod-shaped, or wire-shaped, their short axis is preferably in the range of 1 to 200 nm, more preferably in the range of 2 to 100 nm, and even more preferably in the range of 5 to 50 nm.

[0090] The silver particles mentioned above are preferably silver particles as the main component. However, as long as it does not hinder the plating process described later or impair the removability of the silver particle layer (M1) described later using the etching solution, a portion of the silver constituting the silver particles can be replaced with other metals or mixed with metal components other than silver.

[0091] The metals that are replaced or mixed can be one or more metallic elements selected from the group consisting of gold, platinum, palladium, ruthenium, tin, copper, nickel, iron, cobalt, titanium, indium, and iridium.

[0092] The ratio of the metal replaced or mixed with the silver particles is preferably 5% by mass or less in the silver particles, and more preferably 2% by mass or less from the viewpoint of the plating properties of the silver particle layer (M1) and the removability by the etching solution.

[0093] The silver particle dispersion used to form the silver particle layer (M1) is made by dispersing silver particles in various solvents. The particle size distribution of the silver particles in the dispersion can be uniformly monodisperse, or it can be a mixture of particles within the above-mentioned average particle size range.

[0094] The solvent used in the dispersion of the silver particles can be an aqueous medium or an organic solvent. Examples of aqueous media include distilled water, ion-exchanged water, pure water, ultrapure water, and mixtures thereof with organic solvents mixed with the aforementioned water.

[0095] Examples of organic solvents that can be mixed with water include: methanol, ethanol, n-propanol, isopropanol, ethyl carbitol, ethyl cellosolve, butyl cellosolve, and other alcohol solvents; acetone, methyl ethyl ketone, and other ketone solvents; ethylene glycol, diethylene glycol, propylene glycol, and other alkylene glycol solvents; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and other polyalkylene glycol solvents; and N-methyl-2-pyrrolidone, and other lactam solvents.

[0096] In addition, organic solvents used alone include: alcohol compounds, ether compounds, ester compounds, ketone compounds, etc.

[0097] Examples of alcohol or ether solvents that can be used as solvents for the above-mentioned alcohols include: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, heptanol, hexanol, octanol, nonanol, decanol, undecylol, dodecanol, tridecanol, tetradecanol, pentadecylol, stearyl alcohol, allyl alcohol, cyclohexanol, terpineol, dihydroterpineol, 2-ethyl-1,3-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, and dipropylene glycol. 1,2-Butanediol, 1,3-Butanediol, 1,4-Butanediol, 2,3-Butanediol, Glycerin, 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, etc.

[0098] Examples of ketone solvents include acetone, cyclohexanone, and methyl ethyl ketone. Examples of ester solvents include ethyl acetate, butyl acetate, 3-methoxybutyl acetate, and 3-methoxy-3-methylbutyl acetate. Furthermore, other organic solvents include hydrocarbon solvents such as toluene, particularly hydrocarbon solvents with 8 or more carbon atoms.

[0099] Examples of nonpolar solvents that can be used as hydrocarbon solvents with 8 or more carbon atoms include octane, nonane, decane, dodecane, tridecane, tetradecane, cyclooctane, xylene, mesitylene, ethylbenzene, dodecylbenzene, tetrahydronaphthalene, and trimethylbenzenecyclohexane. These solvents can be used in combination with other solvents as needed. Furthermore, solvents such as mineral oil and naphtha can also be used as mixed solvents.

[0100] There are no particular limitations as long as the solvent described above allows for stable dispersion of the silver particles and a good formation of the silver particle layer (M1) on the insulating layer (A) or the primer layer (B) formed on the insulating layer (A) as described later. Furthermore, one or more solvents may be used.

[0101] Regarding the silver particle content in the aforementioned silver particle dispersion, as long as the various coating methods described above are used, the amount of the silver particle layer (M1) formed on the aforementioned insulating layer (A) is 0.01 to 30 g / m². 2 The viscosity can be adjusted appropriately within the range of the above-mentioned coating methods to achieve the best coating adaptability. The preferred range is 0.1 to 50% by mass, and the more preferred range is 0.5 to 20% by mass.

[0102] In the above-mentioned silver particle dispersion, it is preferable that the silver particles do not aggregate, fuse, or precipitate in the various solvents mentioned above, thus maintaining long-term dispersion stability. It is also preferable that the dispersion contains a dispersant for dispersing the silver particles in the various solvents. As such a dispersant, it is preferable to have a dispersant having functional groups that coordinate with the metal particles. Examples of such dispersants include those having functional groups such as carboxyl, amino, cyano, acetoacetyl, phosphorus-containing groups, thiols, cyanothiols, and glycine groups.

[0103] As the dispersant mentioned above, commercially available or separately synthesized low or high molecular weight dispersants can be used, as long as they are appropriately selected according to the purpose, such as the solvent for dispersing the metal particles and the type of insulating layer (A) to which the metal particle dispersion is coated. For example, suitable dispersants include: dodecyl mercaptan, 1-octyl mercaptan, triphenylphosphine, dodecylamine, polyethylene glycol, polyvinylpyrrolidone, polyethyleneimine, polyvinylpyrrolidone; fatty acids such as myristic acid, caprylic acid, and stearic acid; and polycyclic hydrocarbon compounds with carboxyl groups such as cholic acid, glycyrrhizic acid, and pinoresinic acid. Here, when a silver particle layer (M1) is formed on the primer layer (B) described later, in order to improve the adhesion between the two layers, it is preferable to use a compound having a reactive functional group [Y] that can form a bond with the reactive functional group [X] of the resin used in the primer layer (B) described later.

[0104] Compounds having the reactive functional group [Y] include, for example, compounds having amino, amide, alkanolamide, carboxyl, carboxylic anhydride, carbonyl, acetoacetyl, epoxy, alicyclic epoxy, oxobutane ring, vinyl, allyl, (meth)acryloyl, (terminated) isocyanate, (alkoxy)silyl, silsesquioxane compounds, etc. In particular, considering the ability to further improve the adhesion between the primer layer (B) and the metal particle layer (M1), the aforementioned reactive functional group [Y] is preferably a basic nitrogen atom group. Examples of such basic nitrogen atom groups include, for example, imino, primary amino, secondary amino, etc.

[0105] The aforementioned basic nitrogen atom groups can be present singly or in multiples within the dispersant molecule 1. By containing multiple basic nitrogen atoms in the dispersant, a portion of the basic nitrogen atom groups interacts with the metal particles, contributing to the dispersion stability of the metal particles, while the remaining basic nitrogen atom groups contribute to improving adhesion to the aforementioned insulating layer (A). Furthermore, when a resin having a reactive functional group [X] is used in the primer layer (B) described later, the basic nitrogen atom groups in the dispersant can form bonds with the reactive functional group [X], further improving the adhesion of the subsequently described metal pattern layer (M2) to the aforementioned insulating layer (A), which is therefore preferable.

[0106] Regarding the aforementioned dispersant, considering the stability and coatability of the silver particle dispersion and the ability to form a silver particle layer (M1) that exhibits good adhesion on the aforementioned insulating layer (A), the dispersant is preferably a polymeric dispersant. As such a polymeric dispersant, polyalkylene imides such as polyethylene imide and polypropylene imide, or compounds formed by adding polyoxyalkylene to the aforementioned polyalkylene imides, are preferred.

[0107] The compound formed by adding polyoxyalkylene to the above-mentioned polyalkylene imide can be a compound formed by combining polyethylene imide and polyoxyalkylene in a straight chain, or it can be a compound formed by branching polyoxyalkylene onto the side of the main chain composed of the above-mentioned polyethylene imide.

[0108] Specific examples of compounds formed by adding polyoxyalkylene to the aforementioned polyalkylene imide include: block copolymers of polyethylene imide and polyethylene oxide; compounds that incorporate a polyethylene oxide structure by adding ethylene oxide to a portion of the imino group present in the main chain of polyethylene imide; and compounds formed by reacting the amino group of the polyalkylene imide, the hydroxyl group of the polyethylene oxide, and the epoxy group of the epoxy resin.

[0109] Commercially available products of the aforementioned polyalkylene imides include "PAO2006W", "PAO306", "PAO318", and "PAO718" from the "EPOMIN (registered trademark) PAO series" manufactured by Nippon Catalyst Co., Ltd.

[0110] The number average molecular weight of the above-mentioned polyalkylimide is preferably in the range of 3,000 to 30,000.

[0111] The amount of the dispersant used to disperse the silver particles is preferably in the range of 0.01 to 50 parts by mass relative to 100 parts by mass of the silver particles. Furthermore, considering that the silver particle layer (M1) can be formed on the insulating layer (A) or the primer layer (B) described later and exhibit good adhesion, the amount is preferably in the range of 0.1 to 10 parts by mass relative to 100 parts by mass of the silver particles. Further considering that the plating properties of the silver particle layer (M1) can be improved, the amount is more preferably in the range of 0.1 to 5 parts by mass.

[0112] There are no particular limitations on the method for manufacturing the aforementioned silver particle dispersion; various methods can be used. For example, silver particles manufactured using a gas-phase method such as low-vacuum gas-phase evaporation can be dispersed in a solvent, or a silver particle dispersion can be directly prepared by reducing silver compounds in a liquid phase. Regardless of whether a gas-phase or liquid-phase method is used, the solvent composition of the dispersion during manufacturing and the dispersion during coating can be appropriately changed as needed by replacing or adding solvents. Among gas-phase and liquid-phase methods, the liquid-phase method is particularly suitable from the perspective of dispersion stability and ease of manufacturing process. For example, a liquid-phase method can be used to manufacture the dispersion by reducing silver ions in the presence of the aforementioned polymeric dispersant.

[0113] In the above-mentioned dispersion of silver particles, surfactants, leveling agents, viscosity modifiers, film-forming aids, defoamers, preservatives and other organic compounds can be added as needed.

[0114] Examples of the aforementioned surfactants include: nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene sorbitan tetraoleate, and polyoxyethylene-polyoxypropylene copolymer; anionic surfactants such as fatty acid salts like sodium oleate, alkyl sulfate salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkyl sulfonates, and sodium alkyl diphenyl ether sulfonates; and cationic surfactants such as alkylamine salts, alkyl trimethylammonium salts, and alkyl dimethyl benzylammonium salts.

[0115] As the leveling agent mentioned above, general leveling agents can be used, such as silicone compounds, acetylene glycol compounds, fluorine compounds, etc.

[0116] As viscosity modifiers, common thickeners can be used, such as: acrylic polymers that can be thickened by adjusting to alkalinity, synthetic rubber latex, urethane resins that can be thickened by molecular association, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, polyvinyl alcohol, hydrogenated castor oil, amide wax, oxidized polyethylene, metal soap, dibenzyl sorbitol, etc.

[0117] As the aforementioned film-forming aids, general film-forming aids can be used, such as anionic surfactants like sodium dioctyl sulfosuccinate, hydrophobic nonionic surfactants like sorbitan monooleate, polyether-modified siloxanes, and silicone oils.

[0118] As the aforementioned defoamer, general defoamers can be used, such as silicone-based defoamers, nonionic surfactants, polyethers, higher alcohols, polymer surfactants, etc.

[0119] As the aforementioned preservatives, common preservatives can be used, such as: isothiazolin-based preservatives, triazine-based preservatives, imidazole-based preservatives, pyridine-based preservatives, azole-based preservatives, pyrithione-based preservatives, etc.

[0120] Furthermore, as a more preferred embodiment of the semi-additive laminate of the present invention, a laminate in which a primer layer (B) is further provided between the insulating layer (A) and the conductive silver particle layer (M1) is also provided. The semi-additive laminate with this primer layer is preferred because it further improves the adhesion of the conductive circuit layer (CM1) to the insulating layer (A).

[0121] The aforementioned primer layer (B) can be formed by applying a primer to a portion or the entire surface of the aforementioned insulating layer (A) and removing solvents such as aqueous media and organic solvents contained in the primer. Here, primer refers to a substance used to improve the adhesion of the conductive circuit layer (CM1) to the insulating layer (A), and is a liquid composition formed by dissolving or dispersing various resins described later in a solvent.

[0122] As for the method of applying the primer to the insulating layer (A), there are no particular limitations as long as the primer layer (B) can be formed well. Various coating methods can be appropriately selected according to the shape, size, rigidity, and flexibility of the insulating layer (A) used. Specific coating methods include, for example: gravure printing, offset printing, flexographic printing, pad printing, gravure offset printing, letterpress printing, letterpress reversal printing, screen printing, micro-touch printing, reverse printing, pneumatic doctor blade coating, blade coating, air knife coating, extrusion coating, impregnation coating, transfer roller coating, contact coating, cast coating, spray coating, inkjet printing, die coating, spin coating, rod coating, dip coating, etc.

[0123] Furthermore, as for the method of applying the primer to both sides of the insulating layer (A) in the form of a film, sheet, or plate, there are no particular limitations as long as the primer layer (B) can be formed well, and the coating method exemplified above can be appropriately selected. In this case, the primer layer (B) can be formed on both sides of the insulating layer (A) simultaneously, or it can be formed on one side of the insulating layer (A) and then on the other side.

[0124] To improve the coatability of the primer and enhance the adhesion of the conductive circuit layer (CM1) to the substrate, the insulating layer (A) can be surface-treated before applying the primer. The same surface treatment method used for forming the silver particle layer (M1) on the insulating layer (A) can be employed.

[0125] As a method for forming a primer layer (B) by applying the primer to the surface of the insulating layer (A) and then removing the solvent contained in the coating layer, for example, a method of drying it using a dryer to evaporate the solvent is commonly used. As for the drying temperature, it can be set to a temperature range that allows the solvent to evaporate without adversely affecting the insulating layer (A); room temperature drying or heated drying is acceptable. Specifically, the drying temperature is preferably in the range of 20 to 350°C, more preferably in the range of 60 to 300°C. Furthermore, the drying time is preferably in the range of 1 to 200 minutes, more preferably in the range of 1 to 60 minutes.

[0126] Regarding the aforementioned drying process, air supply may or may not be required. Furthermore, drying can be carried out in the atmosphere, under a displacement atmosphere or flow such as nitrogen or argon, or under a vacuum.

[0127] When the aforementioned insulating layer (A) is a single film, sheet, or plate, it can be dried naturally at the coating site or in a dryer such as an air-cooled or temperature-controlled dryer. Furthermore, when the aforementioned insulating layer (A) is a roll film or sheet, it can be dried by continuously moving the roll within a designated non-heated or heated space after the coating process.

[0128] The thickness of the primer layer (B) can be appropriately selected according to the specifications and uses of the printed wiring board manufactured using the present invention. Considering that the adhesion between the insulating layer (A) and the metal pattern layer (M2) can be further improved, it is preferably in the range of 10nm to 30μm, more preferably in the range of 10nm to 1μm, and even more preferably in the range of 10nm to 500nm.

[0129] When a substance having a reactive functional group [Y] is used in the dispersant of the aforementioned metal particles, the resin forming the primer layer (B) is preferably a resin having a reactive functional group [X] that is reactive to the reactive functional group [Y]. Examples of the aforementioned reactive functional group [X] include: amino, amide, alkanolamide, ketone, carboxyl, carboxylic anhydride, carbonyl, acetoacetyl, epoxy, alicyclic epoxy, oxetane ring, vinyl, allyl, (meth)acryloyl, (terminated)isocyanate, (alkoxy)silyl, etc. Alternatively, silsesquioxane compounds may be used as the compounds forming the primer layer (B).

[0130] In particular, when the reactive functional group [Y] in the above-mentioned dispersant is a basic nitrogen atom group, considering that the adhesion of the conductor circuit layer (CM2) on the above-mentioned insulating layer (A) can be further improved, the resin forming the primer layer (B) is preferably a resin having ketone, carboxyl, carbonyl, acetoacetyl, epoxy, alicyclic epoxy, alkanolamide, isocyanate, vinyl, (meth)acryloyl, or allyl as reactive functional groups [X].

[0131] Examples of resins used to form the primer layer (B) include: urethane resins, acrylic resins, core-shell composite resins with urethane resin as the shell and acrylic resin as the core, epoxy resins, imide resins, amide resins, melamine resins, phenolic resins, urea-formaldehyde resins, and capped isocyanates such as polyvinyl alcohol and polyvinylpyrrolidone obtained by reacting polyisocyanate with capping agents such as phenol. It should be noted that core-shell composite resins with urethane resin as the shell and acrylic resin as the core can be obtained, for example, by polymerizing acrylic monomers in the presence of urethane resin. Furthermore, one or more of these resins may be used.

[0132] Of the resins used to form the primer layer (B), those that generate a reducing compound by heating are preferred, considering their ability to further improve the adhesion of the conductor circuit layer (CM2) on the insulating layer (A). Examples of such reducing compounds include phenolic compounds, aromatic amine compounds, sulfur compounds, phosphoric acid compounds, and aldehyde compounds. Among these reducing compounds, phenolic compounds and aldehyde compounds are preferred.

[0133] When a resin that generates reducing compounds upon heating is used in a primer, reducing compounds such as formaldehyde and phenol will be generated during the heating and drying process when forming the primer layer (B). Specific examples of resins that generate reducing compounds upon heating include: resins polymerized from monomers containing N-alkanol (meth)acrylamide; core-shell composite resins with urethane resin as the shell and resins polymerized from monomers containing N-alkanol (meth)acrylamide as the core; urea-formaldehyde-methanol condensates; urea-melamine-formaldehyde-methanol condensates; poly(N-alkoxyhydroxymethyl (meth)acrylamide); formaldehyde adducts of poly(meth)acrylamide; melamine resins; and phenolic resins, phenol-terminated isocyanates, etc., which generate phenolic compounds upon heating. Among these resins, from the viewpoint of improving adhesion, core-shell composite resins with urethane resin as the shell and a resin polymerized from monomers containing N-alkanol (meth)acrylamide as the core, melamine resin, and phenol-terminated isocyanate are preferred.

[0134] It should be noted that in this 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".

[0135] Resins that generate reducing compounds through heating can be obtained by polymerizing monomers with functional groups that generate reducing compounds through heating using polymerization methods such as free radical polymerization, anionic polymerization, and cationic polymerization.

[0136] As monomers having functional groups that generate reducing compounds upon heating, examples include N-alkanolyl vinyl monomers, specifically: N-hydroxymethyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-propoxymethyl (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, N-n-butoxymethyl (meth)acrylamide, N-isobutoxymethyl (meth)acrylamide, N-pentoxymethyl (meth)acrylamide, N-ethanol (meth)acrylamide, N-propanol (meth)acrylamide, etc.

[0137] In addition, when manufacturing the resin that generates a reducing compound by heating, various other monomers such as (meth)acrylates can be copolymerized together with monomers having functional groups that generate a reducing compound by heating.

[0138] When the aforementioned terminated isocyanate is used as the resin for forming the primer layer (B), the primer layer (B) is formed by the self-reaction between isocyanate groups to form urea diketone bonds, or by the formation of bonds between isocyanate groups and functional groups of other components. These bonds can be formed before or after coating the metal particle dispersion, either by heating.

[0139] Examples of the aforementioned capped isocyanates include substances having functional groups formed by capping the isocyanate group with a capping agent.

[0140] The aforementioned capped isocyanate preferably has the above-mentioned functional groups in the range of 350 to 600 g / mol per mole of capped isocyanate.

[0141] From the viewpoint of improving adhesion, the aforementioned functional groups are preferably 1 to 10 per molecule of the aforementioned capped isocyanate, and more preferably 2 to 5.

[0142] Furthermore, from the viewpoint of improving adhesion, the number average molecular weight of the above-mentioned capped isocyanate is preferably in the range of 1,500 to 5,000, and more preferably in the range of 1,500 to 3,000.

[0143] Furthermore, from the viewpoint of further improving adhesion, it is preferable that the aforementioned end-capped isocyanate has an aromatic ring. Examples of such aromatic rings include phenyl and naphthyl groups.

[0144] It should be noted that the above-mentioned capped isocyanates can be manufactured by reacting some or all of the isocyanate groups of the isocyanate compound with a capping agent.

[0145] Examples of isocyanate compounds that can serve as raw materials for the aforementioned end-capped isocyanates include, for example, polyisocyanate compounds with aromatic rings such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, and naphthalene diisocyanate; aliphatic polyisocyanate compounds or polyisocyanate compounds with alicyclic structures such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, isophthalic diisocyanate, and tetramethyl isophthalic diisocyanate. Additionally, biuret forms, isocyanurate forms, and adducts of the aforementioned polyisocyanate compounds can also be listed.

[0146] In addition, as the aforementioned isocyanate compounds, compounds obtained by reacting the polyisocyanate compounds exemplified above with compounds having hydroxyl or amino groups can also be listed.

[0147] When introducing an aromatic ring into the aforementioned end-capped isocyanate, a polyisocyanate compound having an aromatic ring is preferred. Furthermore, among polyisocyanate compounds having an aromatic ring, 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, isocyanurate form of 4,4'-diphenylmethane diisocyanate, and isocyanurate form of toluene diisocyanate are preferred.

[0148] Examples of end-capping agents used in the manufacture of the aforementioned end-capped isocyanates include: phenolic compounds such as phenol and cresol; lactam compounds such as ε-caprolactam, δ-valeronactam, and γ-butyrolactam; oxime compounds such as formamide oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, methyl isobutyl ketone oxime, 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, butanethiol, dodecyl mercaptan, acetanilide, acetamide, succinimide, maleimide, imidazole, 2-methylimidazole, urea, thiourea, ethylhexene, diphenylaniline, aniline, carbazole, ethyleneimide, polyethyleneimide, 1H-pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole. Preferably, the capping agent is one that can dissociate and generate isocyanate groups by heating in the range of 70 to 200°C, and more preferably, it is one that can dissociate and generate isocyanate groups by heating in the range of 110 to 180°C. Specifically, phenolic compounds, lactam compounds, and oxime compounds are preferred, especially phenolic compounds, which become reducing compounds when the capping agent is desorbed by heating.

[0149] Examples of methods for manufacturing the aforementioned capped isocyanate include: a method of mixing a pre-manufactured isocyanate compound with the capping agent and reacting the mixture; and a method of mixing the capping agent with the raw materials used in manufacturing the isocyanate compound and reacting the mixture.

[0150] More specifically, the above-mentioned end-capped isocyanate can be manufactured by reacting the above-mentioned polyisocyanate compound with a compound having hydroxyl or amino groups to produce an isocyanate compound with isocyanate groups at the end, and then mixing the above-mentioned isocyanate compound with the above-mentioned end-capping agent and reacting it.

[0151] The content of the end-capped isocyanate obtained by the above method in the resin forming the primer layer (B) is preferably in the range of 50 to 100% by mass, more preferably in the range of 70 to 100% by mass.

[0152] Examples of the aforementioned melamine resins include: mono- or polyhydroxymethyl melamine obtained by adding 1 to 6 moles of formaldehyde to 1 mole of melamine; etherifications (degree of etherification arbitrary) of (poly)hydroxymethyl melamines such as trimethoxyhydroxymethyl melamine, tributoxyhydroxymethyl melamine, and hexamethoxyhydroxymethyl melamine; and urea-melamine-formaldehyde-methanol condensates.

[0153] In addition to the method described above using a resin that generates a reducing compound through heating, methods of adding a reducing compound to the resin can also be listed. In this case, examples of the added reducing compounds include: phenolic antioxidants, aromatic amine antioxidants, sulfur-based antioxidants, phosphoric acid antioxidants, vitamin C, vitamin E, sodium ethylenediaminetetraacetate, sulfites, hypophosphite, hydrazine, formaldehyde, sodium borohydride, dimethylamineborane, phenol, etc.

[0154] In this invention, regarding the method of adding a reducing compound to a resin, since the final residual low molecular weight components and ionic compounds may lead to a decrease in electrical properties, it is more preferable to use a resin in which a reducing compound is generated by heating.

[0155] Furthermore, as a preferred resin for forming the aforementioned primer layer (B), resins containing compounds having an aminotriazine ring can be listed. The aforementioned compound having an aminotriazine ring can be a low molecular weight compound or a resin with a higher molecular weight.

[0156] As the aforementioned low molecular weight compounds containing an aminotriazine ring, various additives containing an aminotriazine ring can be used. Examples of commercially available products include: 2,4-diamino-6-vinyl-triazine ("VT" manufactured by Shikoku Kasei Corporation), "VD-3" and "VD-4" (compounds containing an aminotriazine ring and a hydroxyl group) manufactured by Shikoku Kasei Corporation, and "VD-5" (compound containing an aminotriazine ring and an ethoxysilyl group) manufactured by Shikoku Kasei Corporation. These compounds can be used as additives by adding one or more of them to the resin forming the primer layer (B).

[0157] The amount of the low molecular weight compound having an aminotriazine ring used is preferably 0.1 to 50 parts by mass relative to 100 parts by mass of the resin, and more preferably 0.5 to 10 parts by mass.

[0158] As for the aforementioned resins containing an aminotriazine ring, resins in which an aminotriazine ring is introduced into the polymer chain of the resin via covalent bonds can also be suitably used. Specifically, aminotriazine-modified phenolic varnish resins can be cited as an example.

[0159] The aforementioned aminotriazine-modified phenolic varnish resin is a phenolic varnish resin formed by the combination of an aminotriazine ring structure and a phenolic structure via a methylene group. This aminotriazine-modified phenolic varnish resin can be obtained, for example, by co-condensing aminotriazine compounds such as melamine, benzoguanidine, and acetylguanidine with phenolic compounds such as phenol, cresol, butylphenol, bisphenol A, phenylphenol, naphthol, and resorcinol, and formaldehyde, in the presence of a weakly basic catalyst such as an alkylamine, or in the absence of a catalyst, near neutrality; or by reacting alkyl ethers of aminotriazine compounds such as methylated melamine with the aforementioned phenolic compounds.

[0160] The aforementioned aminotriazine-modified phenolic varnish resin preferably does not contain hydroxymethyl groups. Furthermore, the aforementioned aminotriazine-modified phenolic varnish resin may contain molecules that are generated as byproducts during its manufacturing process, such as molecules where only the aminotriazine structure is methylene-bound or molecules where only the phenol structure is methylene-bound. It may also contain a small amount of unreacted raw materials.

[0161] Examples of phenolic structures include, for example, phenol residues, cresol residues, butylphenol residues, bisphenol A residues, phenylphenol residues, naphthol residues, and resorcinol residues. Furthermore, the term "residue" here refers to a structure formed by the removal of at least one hydrogen atom from the carbon atom bound to the aromatic ring. For example, in the case of phenol, it refers to hydroxyphenyl.

[0162] Examples of triazine structures derived from aminotriazine compounds such as melamine, benzoguanamine, and acetylguanidine can be cited as examples.

[0163] One or more of the phenolic and triazine structures described above can be used. Furthermore, to further improve adhesion, the phenolic structure is preferably a phenol residue, and the triazine structure is preferably derived from melamine.

[0164] Furthermore, considering the ability to further improve adhesion, the hydroxyl value of the above-mentioned aminotriazine modified phenolic varnish resin is preferably 50 mg KOH / g or more and 200 mg KOH / g or less, more preferably 80 mg KOH / g or more and 180 mg KOH / g or less, and even more preferably 100 mg KOH / g or more and 150 mg KOH / g or less.

[0165] The above-mentioned aminotriazine modified phenolic varnish resin can be used in combination with one or more of the same resin.

[0166] Furthermore, when using aminotriazine-modified phenolic varnish resin as the above-mentioned compound having an aminotriazine ring, it is preferable to use epoxy resin in conjunction.

[0167] Examples of epoxy resins mentioned above include: bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, cresol phenolic varnish type epoxy resin, phenol phenolic varnish type epoxy resin, bisphenol A phenolic varnish type epoxy resin, alcohol ether type epoxy resin, tetrabromobisphenol A type epoxy resin, naphthalene type epoxy resin, phosphorus-containing epoxy compounds having a structure derived from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivatives, epoxy resins having a structure derived from dicyclopentadiene derivatives, and epoxides of epoxidized soybean oil and other oils. One or more of these epoxy resins may be used.

[0168] Among the aforementioned epoxy resins, considering the ability to further improve adhesion, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, cresol phenolic varnish type epoxy resin, phenolic varnish type epoxy resin, and bisphenol A phenolic varnish type epoxy resin are preferred, with bisphenol A type epoxy resin being particularly preferred.

[0169] Furthermore, considering the need to further improve adhesion, the epoxy equivalent of the epoxy resin is preferably 100g / equivalent or more and 300g / equivalent or less, more preferably 120g / equivalent or more and 250g / equivalent or less, and even more preferably 150g / equivalent or more and 200g / equivalent or less.

[0170] When the primer layer (B) is a layer containing aminotriazine-modified phenolic varnish resin and epoxy resin, in order to further improve the adhesion, the molar ratio [(x) / (y)] of the phenolic hydroxyl group (x) in the aminotriazine-modified phenolic varnish resin to the epoxy group (y) in the epoxy resin is preferably 0.1 to 5, more preferably 0.2 to 3, and even more preferably 0.3 to 2.

[0171] When forming a layer containing an aminotriazine-modified phenolic varnish resin and an epoxy resin as the aforementioned primer layer (B), a primer resin composition containing the aforementioned compound having an aminotriazine ring and an epoxy resin is used.

[0172] Furthermore, in the primer resin composition for forming the primer layer (B) containing aminotriazine-modified phenolic varnish resin and epoxy resin, other resins such as urethane resin, acrylic resin, end-capped isocyanate resin, melamine resin, and phenolic resin may also be added as needed. One or more of these other resins may be used.

[0173] From the viewpoint of coatability and film-forming properties, the primer used to form the above-mentioned primer layer (B) preferably contains 1 to 70% by mass of the above-mentioned resin, and more preferably 1 to 20% by mass.

[0174] Furthermore, various organic solvents and aqueous media can be listed as solvents that can be used in the aforementioned primers. Examples of organic solvents include toluene, ethyl acetate, methyl ethyl ketone, and cyclohexanone. Examples of aqueous media include water, organic solvents mixed with water, and mixtures thereof.

[0175] Examples of organic solvents that can be mixed with water include: methanol, ethanol, n-propanol, isopropanol, ethyl carbitol, ethyl cellosolve, butyl cellosolve, and other alcohol solvents; acetone, methyl ethyl ketone, and other ketone solvents; ethylene glycol, diethylene glycol, propylene glycol, and other alkylene glycol solvents; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and other polyalkylene glycol solvents; and N-methyl-2-pyrrolidone, and other lactam solvents.

[0176] Furthermore, the resin forming the primer layer (B) may, as needed, have functional groups such as alkoxysilyl, silanol, hydroxyl, and amino groups that facilitate crosslinking reactions. Regarding the crosslinking structure formed using these functional groups, the crosslinking structure can be formed before the subsequent step of forming the silver particle layer (M1), or it can be formed after the step of forming the silver particle layer (M1). In the case where the crosslinking structure is formed after the step of forming the silver particle layer (M1), the crosslinking structure can be formed in the primer layer (B) before forming the conductive circuit layer (CM1), or it can be formed in the primer layer (B) after forming the conductive circuit layer (CM1), for example, by curing.

[0177] In the aforementioned primer layer (B), known substances may be added as needed, primarily crosslinking agents, as well as pH adjusters, film-forming aids, leveling agents, thickeners, water-repellent agents, defoamers, etc.

[0178] Examples of crosslinking agents include metal chelating compounds, polyamine compounds, aziridine compounds, metal salt compounds, and isocyanate compounds. Examples of thermal crosslinking agents that form crosslinked structures by reacting at relatively low temperatures of around 25–100°C include melamine-based compounds and epoxy compounds. Thermal crosslinking agents, such as azoline compounds, carbodiimide compounds, and terminally capped isocyanate compounds, are used to form crosslinked structures by reacting at relatively high temperatures above 100°C, as well as various photocrosslinking agents. When using the above-mentioned aminotriazine-modified phenolic varnish resin and epoxy resin as the primer layer (B), it is preferable to use a polycarboxylic acid as the crosslinking agent in the primer resin composition. Examples of such polycarboxylic acids include trimellitic anhydride, pyromellitic anhydride, maleic anhydride, and succinic acid. One or more of these crosslinking agents can be used. Furthermore, among these crosslinking agents, trimellitic anhydride is preferred from the viewpoint of further improving adhesion.

[0179] The amount of the crosslinking agent used varies depending on the type, but from the viewpoint of improving the adhesion of the conductive circuit layer (CM1) to the substrate, it is preferably in the range of 0.01 to 60 parts by mass relative to the total 100 parts by mass of the resin contained in the primer, 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.

[0180] When using the aforementioned crosslinking agent, the crosslinked structure can be formed before the subsequent step of forming the silver particle layer (M1), or it can be formed after the step of forming the silver particle layer (M1). When forming the crosslinked structure after the step of forming the silver particle layer (M1), the crosslinked structure can be formed on the primer layer (B) before forming the conductive circuit layer (CM1), or it can be formed on the primer layer (B) after forming the conductive circuit layer (CM1), for example, by curing.

[0181] In this invention, the method of forming the silver particle layer (M1) on the primer layer (B) is the same as the method of forming the silver particle layer (M1) on the insulating layer (A).

[0182] In addition, regarding the primer layer (B), similarly to the insulating layer (A), a surface treatment can be performed before coating the silver particle dispersion to improve the coatability of the silver particle dispersion and the adhesion of the conductive circuit layer (CM1) to the substrate.

[0183] The semi-additive process of the present invention uses a laminate formed by stacking a copper layer (M2) on the silver particle layer (M1) mentioned above.

[0184] The copper layer (M2) is a layer that protects the conductivity of the silver particle layer (M1) in the etching process of the printed wiring board manufacturing method described later, which is stacked on the silver particle layer (M1) to remove palladium, conductive polymer, and carbon adsorbed outside the inner wall surface of the holes formed in the insulating layer (A). The insulating layer (A) has a structure that is connected to the conductor circuit layer (CM2) of the inner printed wiring substrate.

[0185] From the viewpoint that the thickness of the copper layer (M2) described above can be efficiently exposed without damaging the silver particle layer (M1) during the etching process of the copper layer (M2) in the printed wiring board manufacturing method described later, the thickness is preferably 0.1 μm to 2 μm, and more preferably 0.5 μm to 1.5 μm.

[0186] In the semi-additive laminate of the present invention, as a method for forming the copper layer (M2) on the conductive silver particle layer (M1), it can be formed by performing a dry or wet copper plating method on the conductive silver particle layer (M1).

[0187] Examples of dry copper plating methods include vacuum evaporation, ion plating, and sputtering. Examples of wet copper plating methods include electroless copper plating using the aforementioned silver particle layer (M1) as a plating catalyst, electrolytic copper plating, and combinations of electroless and electrolytic copper plating. Using electrolytic plating increases the plating deposition rate, thus improving manufacturing efficiency.

[0188] There are no particular limitations on the copper plating method used to form a copper layer (M2) on the aforementioned silver particle layer (M1). It can be formed by vacuum evaporation, ion plating, or sputtering as dry plating methods, or by electroless copper plating, electrolytic copper plating, or a combination of electroless and electrolytic copper plating as wet plating methods. In addition, it can be formed by combining dry plating and wet plating methods. In all cases, commonly known copper plating methods can be appropriately used.

[0189] When the insulating layer (A) is formed on both planes of the substrate, the copper plating is preferably formed on the silver particle layer (A) on both surfaces with the same thickness of copper layer (M2).

[0190] In the process of forming the copper layer (M2) by the above-described copper plating method, the surface of the silver particle layer (M1) can be surface-treated as needed. Examples of such surface treatments include cleaning with acidic or alkaline cleaning solutions, corona treatment, plasma treatment, UV treatment, gas-phase ozone treatment, liquid-phase ozone treatment, and treatment using surface treatment agents, all without damaging the resist pattern formed on the surface of the silver particle layer (M1). These surface treatments can be performed using one method or in combination of two or more methods.

[0191] Step 1 of the method for manufacturing a multilayer printed circuit board using the semi-additive laminate of the present invention comprises the following steps: forming a hole in the semi-additive laminate from the insulating layer (A) to the conductor circuit layer (CM2). The semi-additive laminate is a semi-additive laminate in which the insulating layer (A), the silver particle layer (M1), and the copper layer (M2) are sequentially laminated on an inner printed circuit substrate on an insulating material where the conductor circuit layer (CM2) is formed, and the thickness of the copper layer (M2) is 0.1 μm to 2 μm, or a semi-additive laminate in which a primer layer (B) is further laminated between the insulating layer (A) and the silver particle layer (M1).

[0192] In step 1, as a method for creating the holes in the conductor circuit layer (CM2) in the semi-additive laminate, any known and commonly used method can be appropriately selected. For example, methods such as drilling, laser processing, processing methods that combine laser processing of openings in the copper layer with reagent etching of the insulating layer using oxidants, alkaline reagents, acidic reagents, etc., and processing methods that combine etching of the hole pattern of the copper foil using resist with reagent etching of the insulating layer using oxidants, alkaline reagents, acidic reagents, etc.

[0193] In these hole processing methods, a laser-based hole processing method is preferred for forming non-through holes for connection to the conductor circuit layer (CM2) formed on the inner printed wiring substrate. Furthermore, the multilayer printed wiring board of the present invention can have a structure that not only electrically connects to the conductor circuit layer (CM2) formed on the inner printed wiring substrate, but also electrically connects both sides through through holes connecting both sides of the substrate. The through holes connecting both sides and the non-through holes for connection to the conductor circuit layer (CM2) can be formed simultaneously in step 1 described above.

[0194] The hole diameter formed in the above-mentioned hole-opening process is preferably in the range of 0.01 to 1 mm, more preferably in the range of 0.02 to 0.5 mm, and even more preferably in the range of 0.03 to 0.1 mm.

[0195] Organic and inorganic contaminants (smear) generated during hole drilling can cause poor plating adhesion, reduced plating bonding, and damage to the plating appearance during the plating processes for two-sided electrical connection and formation of the conductive circuit layer (CM1) described later. Therefore, it is preferable to remove the contaminants (smear). Examples of methods for removing smear include: dry treatment such as plasma treatment and backsputtering; cleaning treatment using aqueous solutions of oxidizing agents such as potassium permanganate; cleaning treatment using aqueous solutions of alkalis or acids; and wet treatment using organic solvents.

[0196] Step 2 of the method for manufacturing a printed wiring board using the semi-additive method of the present invention is the following step: applying palladium, a conductive polymer, or carbon to the surface of the laminate having holes formed in the insulating layer (A) and connected to the conductor circuit layer (CM2) of the inner printed wiring substrate in step 1 to make the hole surface conductive.

[0197] As a method for making the surface of the aforementioned through-hole conductive, for example, the method described as "direct plating method" in Toyonaga Minoru, Circuit Technology, vol.8, No.1 (1993), pp.47-59 can be referred to.

[0198] As a method to make the surface of the hole connected to the above-mentioned conductor circuit layer (CM2) conductive, any one of the four methods described in the above-mentioned documents can be used: (1) palladium-tin colloidal system, (2) tin-free palladium system, (3) conductive polymer system, and (4) graphite system.

[0199] As a method for making the surface of the hole connected to the conductor circuit layer (CM2) conductive using palladium-tin colloid, it can be implemented by treating the surface of the laminate with the hole with a cleaner-conditioner, allowing the tin-palladium colloid to be adsorbed onto the surface, and then removing the tin by an accelerator treatment. Alternatively, a method can be used to further convert palladium into palladium sulfide to improve conductivity.

[0200] Alternatively, as a method for making the surface of the holes connected to the conductive circuit layer (CM2) conductive using a conductive polymer, an oxidative polymerization method can be used to polymerize a monomer of a pyrrole derivative. After treating the surface of the laminate with the through holes with a conditioning agent, it is treated with an aqueous permanganate solution to form MnO2 on the surface of the through holes formed in the insulating layer (A). If the substrate surface is immersed in an aqueous solution of a monomer containing a high-boiling-point alcohol, and then immersed in an aqueous solution of dilute sulfuric acid, polymerization occurs on the surface coated with MnO2 to form a conductive polymer, thereby achieving conductivity.

[0201] Furthermore, as a method for making the surface of the holes connected to the conductor circuit layer (CM2) conductive using graphite, the surface of the substrate with the holes connected to the conductor circuit layer (CM2) can be treated with a suspended carbon black solution using a semi-additive process, causing the entire substrate surface to adsorb carbon. By treating the surface of the laminate with the holes connected to the conductor circuit layer (CM2) with a conditioning agent, the substrate surface can be positively charged, allowing the negatively charged carbon black to adsorb onto the surface, thus ensuring conductivity.

[0202] As a method for making the surface of the hole connected to the conductor circuit layer (CM2) conductive, any of the methods described above using palladium, conductive polymers, or carbon can be employed, utilizing commercially available and commonly known processes. For example, in a tin-palladium process, a method known as the CRIMSON process can be used; in a graphite system, for example, a process known as a black hole process can be used. Among these methods, from the viewpoint of material and process cost, the method of using carbon for conductivity is preferred.

[0203] In this invention, as described above, when a through-hole is simultaneously connected to both sides of a substrate, the through-hole can be made conductive using the methods described above, employing palladium, a conductive polymer, and carbon. The conductivity of the through-hole can be performed simultaneously with the conductivity of the hole surface connected to the conductor circuit layer (CM2).

[0204] Step 3 of the method for manufacturing a printed wiring board using the semi-additive method of the present invention comprises the following step: etching the copper layer (M2) to expose the conductive silver particle layer (M1). This step exposes the conductive silver particle layer (M1), which is used to form the conductive circuit layer (CM1) in subsequent steps, and also serves to remove the palladium, conductive polymer, and carbon used in step 2 to make the holes connected to the conductive circuit layer (CM2) conductive from the plated seed layer.

[0205] In step 3, the reagent used to etch away the 0.1μm to 2μm thick copper layer (M2) stacked on the conductive silver particle layer (M1) is not particularly limited as long as it can efficiently etch the copper layer (M2) without damaging the underlying silver particle layer (M1). Commonly known copper micro-etching solutions or soft etching solutions can be used. As the etching solution for the copper layer (M2), aqueous solutions of persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, or aqueous solutions of sulfuric acid / hydrogen peroxide can be used.

[0206] The concentration of the aqueous solution of persulfate or the aqueous solution of sulfuric acid / hydrogen peroxide can be appropriately selected according to the thickness of the copper layer (M2) of the semi-additive laminate used to manufacture the printed wiring board and the design of the manufacturing apparatus. In the process used, it is preferable to set the etching rate of the copper layer to be less than 2 μm / min. From the viewpoint of efficiently removing the copper layer (M2) and preventing damage to the conductive silver particle layer (M1) as the substrate layer, it is more preferable to set the etching rate to be 0.1 μm / min to 1.5 μm / min.

[0207] The laminate obtained by etching the copper layer (M2) in step 3 of the method for manufacturing a printed circuit board using a semi-additive laminate of the present invention, after a drying process, can be used as a semi-additive laminate using a silver particle layer (M1) as a conductive seed crystal. That is, the laminate obtained by etching the copper layer (M2) in step 3 of the method for manufacturing a printed circuit board using a semi-additive laminate of the present invention is characterized by…

[0208] A conductive silver particle layer (M1) is formed on the surface of the insulating layer (A) stacked on the inner printed wiring substrate. The inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0209] Furthermore, the insulating layer (A) has a hole that connects to the conductor circuit layer (CM2), and the surface of the hole is a substrate that ensures conductivity through any one of palladium, a conductive polymer, or carbon.

[0210] In step 4 of the method for manufacturing a printed wiring board using the semi-additive laminate of the present invention, a pattern resist for forming a circuit pattern is formed on a silver particle layer (M1) on which the upper copper layer (M2) has been removed in step 3.

[0211] In the process of forming the patterned resist in step 4, in order to improve the adhesion with the resist layer, the surface of the silver particle layer (M1) may undergo surface treatments such as cleaning with acidic or alkaline cleaning solutions, corona treatment, plasma treatment, UV treatment, gas phase ozone treatment, liquid phase ozone treatment, or treatment with surface treatment agents before forming the resist. These surface treatments may be performed using one method or by combining two or more methods.

[0212] As for the above-mentioned treatment using surface treatment agents, for example, the following methods can be used: the method described in Japanese Patent Application Publication No. 7-258870, which uses a triazole compound, a silane coupling agent, and a rust inhibitor composed of an organic acid; the method described in Japanese Patent Application Publication No. 2000-286546, which uses an organic acid, a benzotriazole rust inhibitor, and a silane coupling agent; the method described in Japanese Patent Application Publication No. 2002-363189, which uses a substance with a structure formed by combining a nitrogen-containing heterocyclic compound such as triazole or thiadiazole with a silane such as trimethoxysilyl or triethoxysilyl via an organic group having a sulfide bond; and the method described in WO2013 / 186941, which uses... Methods for treating silane compounds having a triazine ring and an amino group; methods for treating imidazole silane compounds obtained by reacting a formyl imidazole compound with an aminopropyl silane compound, as described in Japanese Patent Application Publication No. 2015-214743; methods for treating with azole silane compounds, as described in Japanese Patent Application Publication No. 2016-134454; methods for treating with an aromatic compound having an amino and an aromatic ring in one molecule, a polybasic acid having two or more carboxyl groups, and a solution containing halide ions, as described in Japanese Patent Application Publication No. 2017-203073; methods for treating with a surface treatment agent containing a triazole silane compound, as described in Japanese Patent Application Publication No. 2018-16865, etc.

[0213] To form a metallic pattern on a surface using the semi-additive method of the present invention with a laminate, for a photosensitive resist, the pattern is exposed using active light via a photomask or a direct exposure machine. The exposure amount can be set appropriately as needed. A developing solution is used to remove the latent image formed on the photosensitive resist by exposure, thereby forming a patterned resist.

[0214] Examples of developers include 0.3 to 2% by mass dilute alkaline aqueous solutions such as sodium carbonate or potassium carbonate. Surfactants, defoamers, and small amounts of organic solvents to promote development can be added to these dilute alkaline aqueous solutions. Alternatively, by immersing the exposed substrate in the developer or by spraying the developer onto the resist using a sprayer, a pattern resist with the patterned areas removed can be formed.

[0215] When forming patterned resist, plasma-based descaling and commercially available resist residue removers can be used to remove resist residues such as skirts at the interface between the cured resist and the substrate, and resist deposits remaining on the substrate surface.

[0216] As the photosensitive resist used in this invention, commercially available resist inks, liquid resists, and dry film resists can be used, as long as they are appropriately selected according to the resolution of the target pattern, the type of exposure machine used, the type of reagent used in the subsequent plating process, pH, etc.

[0217] Commercially available resist inks include, for example, "Mounting Resist MA-830" and "Etching Resist X-87" manufactured by Taiyo Ink Manufacturing Co., Ltd.; etching and plating resists from NAZDAR Corporation; and the "Etching Resist PLAS FINE PER" series and "Mounting Resist PLAS FINE PPR" series manufactured by Muyo Chemical Industry Co., Ltd. Additionally, as electrodeposition resists, examples include the "Eagle" and "Pepper" series from Dow Chemical Company. Furthermore, as commercially available dry films, examples include the "Photec" series manufactured by Hitachi Chemical Co., Ltd.; the "ALPHO" series manufactured by Nikko-Materials Co., Ltd.; the "Sunfort" series manufactured by Asahi Kasei Corporation; and the "Riston" series manufactured by DuPont.

[0218] For efficient manufacturing of printed circuit boards, dry film resists are readily available, especially in the case of forming microcircuits, where only semi-additive dry films are required. Commercially available dry films for this purpose include, for example: Nikko Materials Co., Ltd.'s "ALFO LDF500" and "NIT2700", Asahi Kasei Corporation's "Sunfort UFG-258", Hitachi Chemical Co., Ltd.'s "RD series (RD-2015, 1225)" and "RY series (RY-5319, 5325)", and DuPont's "PlateMaster series (PM200, 300)".

[0219] In step 5 of the method for manufacturing the printed wiring board of the present invention, the above-mentioned conductive silver particle layer (M1) is used as the cathode electrode for electrolytic copper plating. As described above, the silver particle layer (M1) exposed by development is subjected to a process based on electrolytic copper plating, thereby enabling the connection of non-through holes for connection with the conductor circuit layer (CM2) by copper plating, and simultaneously forming a conductive circuit layer (CM1) with a circuit pattern.

[0220] Before forming the conductive circuit layer (CM1) using the aforementioned electrolytic copper plating method, the surface of the silver particle layer (M1) may be surface-treated as needed. Examples of such surface treatments include cleaning with acidic or alkaline cleaning solutions, corona treatment, plasma treatment, UV treatment, gas-phase ozone treatment, liquid-phase ozone treatment, and treatment using surface treatment agents, all without damaging the resist pattern formed on the surface of the silver particle layer (M1). These surface treatments can be performed using one method or a combination of two or more methods.

[0221] When forming a conductive circuit layer (CM1) with a circuit pattern on an insulating substrate using the semi-additive method of the present invention, annealing can be performed after plating to alleviate the stress of the plating and improve the adhesion. Annealing can be performed before the etching process described later, after the etching process, or both before and after the etching process.

[0222] The annealing temperature can be appropriately selected within the range of 40–300°C, depending on the heat resistance of the substrate and the intended use. A range of 40–250°C is preferred, and a range of 40–200°C is more preferable to suppress oxidative degradation of the coating. Furthermore, within the temperature range of 40–200°C, the annealing time can be from 10 minutes to 10 days, while annealing at temperatures exceeding 200°C can be from approximately 5 minutes to 10 hours. Additionally, a rust inhibitor can be appropriately applied to the coating surface during annealing.

[0223] In step 6 of the method for manufacturing the printed wiring board of the present invention, after the conductive circuit layer (CM1) is formed by plating in step 5, the pattern resist formed using the aforementioned photosensitive resist is peeled off, and the silver particle layer (M1) of the non-conductive circuit pattern formation area is removed using an etching solution. The removal of the pattern resist can be performed under the recommended conditions described in the catalog, instruction manual, etc., of the photosensitive resist used. Furthermore, as the resist stripping solution used for stripping the pattern resist, a commercially available resist stripping solution or a 1.5-3% by mass aqueous solution of sodium hydroxide or potassium hydroxide set at 45-60°C can be used. The resist stripping can be performed by immersing the substrate on which the conductive circuit layer (CM1) with the aforementioned circuit pattern is formed in the stripping solution, or by spraying the stripping solution using a sprayer or the like.

[0224] Furthermore, the etching solution used to remove the silver particle layer (M1) of the non-conductive circuit pattern formation area preferably selectively etches only the silver particle layer (M1) and does not etch the copper forming the conductive circuit layer (CM1). A mixture of carboxylic acid and hydrogen peroxide can be cited as an example of such an etching solution.

[0225] Examples of the aforementioned carboxylic acids include, for instance: acetic acid, formic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, alginic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, oxalic acid, malonic acid, succinic acid, benzoic acid, salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, gallic acid, benzenehexacarboxylic acid, cinnamic acid, pyruvic acid, lactic acid, malic acid, citric acid, fumaric acid, maleic acid, aconitic acid, glutaric acid, adipic acid, and amino acids. One or more of these carboxylic acids can be used. Considering the ease of manufacturing and handling the etching solution, acetic acid is preferred as the primary carboxylic acid.

[0226] It is believed that if a mixture of carboxylic acid and hydrogen peroxide is used as the etching solution, peroxycarboxylic acid will be generated through the reaction of hydrogen peroxide and carboxylic acid. It is speculated that the generated peroxycarboxylic acid inhibits the dissolution of copper constituting the conductive circuit layer (CM1) and preferentially dissolves silver constituting the silver particle layer (M1).

[0227] As for the mixing ratio of the above-mentioned carboxylic acid and hydrogen peroxide, considering the ability to suppress the dissolution of the copper conductive circuit layer (CM1), it is preferable to set the hydrogen peroxide in the range of 2 to 100 moles relative to 1 mole of carboxylic acid, and more preferably in the range of 2 to 50 moles of hydrogen peroxide.

[0228] The mixture of the aforementioned carboxylic acid and hydrogen peroxide is preferably an aqueous solution prepared by diluting with water. Furthermore, considering the ability to suppress the effect of temperature rise in the etching solution, the content ratio of the mixture of the aforementioned carboxylic acid and hydrogen peroxide in the aqueous solution is preferably in the range of 2 to 65% by mass, more preferably in the range of 2 to 30% by mass.

[0229] The water used for dilution is preferably water that has had ionic substances and impurities removed, such as ion-exchanged water, pure water, or ultrapure water.

[0230] In the above etching solution, a protective agent can be further added to protect the conductive circuit layer (CM1) of the copper and inhibit its dissolution. A azole compound is preferably used as the protective agent.

[0231] Examples of the aforementioned azole compounds include, for example: imidazole, pyrazole, triazole, tetraazole, etc. azole, thiazole, selenazole diazole, thiadiazole, Triazole, thiatriazole, etc.

[0232] Specific examples of the aforementioned azole compounds include, for instance, 2-methylbenzimidazole, aminotriazole, 1,2,3-benzotriazole, 4-aminobenzotriazole, 1-diaminomethylbenzotriazole, aminotetrazole, phenyltetrazole, 2-phenylthiazole, benzothiazole, etc. One of these azole compounds may be used, or two or more may be used in combination.

[0233] The concentration of the above-mentioned azole compound in the etching solution is preferably in the range of 0.001 to 2% by mass, more preferably in the range of 0.01 to 0.2% by mass.

[0234] In addition, in the above-mentioned etching solution, in order to suppress the dissolution of the copper conductive circuit layer (CM1), it is preferable to add polyalkylene glycol as a protective agent.

[0235] Examples of the aforementioned polyalkylene glycols include, for example, water-soluble polymers such as polyethylene glycol, polypropylene glycol, and polyoxyethylene-polyoxypropylene block copolymers. Polyethylene glycol is preferred. Furthermore, the number average molecular weight of the polyalkylene glycol is preferably in the range of 200 to 20,000.

[0236] The concentration of the above-mentioned polyalkylene glycol in the etching solution is preferably in the range of 0.001 to 2% by mass, and more preferably in the range of 0.01 to 1% by mass.

[0237] In the above etching solution, in order to suppress pH fluctuations, additives such as sodium salts, potassium salts, and ammonium salts of organic acids can be added as needed.

[0238] In the semi-additive laminate of the present invention, the removal of the silver particle layer (M1) of the non-patterned portion can be performed by: after forming the conductive circuit layer (CM1), peeling off the patterned resist formed using the photosensitive resist, immersing the peeled substrate in the etching solution, or spraying the etching solution onto the substrate using a sprayer or the like.

[0239] When using an etching apparatus to remove the silver particle layer (M1) of the non-patterned portion, for example, the etching solution can be prepared in such a way that all the components of the etching solution become a specific composition and then supplied to the etching apparatus, or each component of the etching solution can be supplied to the etching apparatus separately and the components can be mixed in the apparatus to form a specific composition.

[0240] The above-mentioned etching solution is preferably used in a temperature range of 10 to 35°C. Especially when using an etching solution containing hydrogen peroxide, it is preferable to use it in a temperature range below 30°C to suppress the decomposition of hydrogen peroxide.

[0241] After removing the silver particle layer (M1) using the aforementioned etching solution, in order to prevent the silver components dissolved in the etching solution from adhering to and remaining on the printed circuit board, a further cleaning operation can be performed in addition to water rinsing. During the cleaning operation, a cleaning solution that dissolves silver oxide, silver sulfide, and silver chloride but hardly dissolves silver is preferably used. Specifically, an aqueous solution containing thiosulfate or tris(3-hydroxyalkyl)phosphine, or an aqueous solution containing mercaptocarboxylic acid or its salt, is preferably used as the cleaning reagent.

[0242] Examples of the aforementioned thiosulfates include, for example, ammonium thiosulfate, sodium thiosulfate, and potassium thiosulfate. Additionally, examples of the aforementioned tris(3-hydroxyalkyl)phosphine include, for example, tris(3-hydroxymethyl)phosphine, tris(3-hydroxyethyl)phosphine, and tris(3-hydroxypropyl)phosphine. One of these thiosulfates or tris(3-hydroxyalkyl)phosphines may be used, or two or more may be used in combination.

[0243] The concentration of the aqueous solution containing thiosulfate can be set appropriately according to the process time and the characteristics of the cleaning equipment used. It is preferably in the range of 0.1% to 40% by mass, and from the viewpoint of cleaning efficiency and reagent stability during continuous use, it is more preferably in the range of 1% to 30% by mass.

[0244] Furthermore, the concentration of the aqueous solution containing the above-mentioned tris(3-hydroxyalkyl)phosphine can be appropriately set according to the process time, the characteristics of the cleaning device used, etc., and is preferably in the range of 0.1% to 50% by mass. From the viewpoint of cleaning efficiency and reagent stability during continuous use, it is more preferably in the range of 1% to 40% by mass.

[0245] Examples of the aforementioned thiocarboxylic acids include, for example, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, cysteine, and N-acetylcysteine. Additionally, examples of salts of the aforementioned thiocarboxylic acids include, for example, alkali metal salts, ammonium salts, and amine salts.

[0246] The concentration of the aqueous solution of mercaptocarboxylic acid or its salt is preferably in the range of 0.1% to 20% by mass, and more preferably in the range of 0.5% to 15% by mass from the viewpoint of cleaning efficiency and process cost when performing large-scale processing.

[0247] As a method for performing the above-mentioned cleaning operation, examples include: immersing the printed circuit board obtained after etching away the silver particle layer (M1) of the non-patterned portion in the cleaning reagent; or spraying the cleaning reagent onto the printed circuit board using a sprayer or the like. Regarding the temperature of the cleaning reagent, it can be used at room temperature (25°C), but for the purpose of stable cleaning without being affected by external temperature, the temperature can be set to 30°C, for example.

[0248] In addition, the process of removing the silver particle layer (M1) of the non-patterned area using etching solution and the cleaning operation can be repeated as needed.

[0249] As described above, after the silver particle layer (M1) of the non-patterned portion of the printed wiring board of the present invention is removed using the aforementioned etching solution, a further cleaning operation can be performed as needed to further improve the insulation of the non-patterned portion. In this cleaning operation, for example, an alkaline permanganate solution obtained by dissolving potassium permanganate or sodium permanganate in an aqueous solution of potassium hydroxide or sodium hydroxide can be used.

[0250] Cleaning using the aforementioned alkaline permanganate solution can include: immersing the printed circuit board obtained by the above method in an alkaline permanganate solution set at 20–60°C; and spraying the alkaline permanganate solution onto the printed circuit board using a sprayer or similar device. To improve the wettability of the alkaline permanganate solution on the substrate surface and increase cleaning efficiency, the printed circuit board can be treated by contacting it with a water-soluble organic solvent containing alcoholic hydroxyl groups before cleaning. Examples of such organic solvents include methanol, ethanol, n-propanol, and isopropanol. One or more of these organic solvents can be used.

[0251] The concentration of the alkaline permanganate solution can be selected appropriately as needed. It is preferable to dissolve 0.1 to 10 parts by mass of potassium permanganate or sodium permanganate in 100 parts by mass of a 0.1 to 10% by mass aqueous solution of potassium hydroxide or sodium hydroxide. From the viewpoint of cleaning efficiency, it is more preferable to dissolve 1 to 6 parts by mass of potassium permanganate or sodium permanganate in 100 parts by mass of a 1 to 6% by mass aqueous solution of potassium hydroxide or sodium hydroxide.

[0252] When performing the above-mentioned cleaning with alkaline permanganate solution, it is preferable to treat the cleaned printed circuit board with a liquid having neutralizing and reducing properties after cleaning with the alkaline permanganate solution. Examples of such neutralizing and reducing liquids include, for example, 0.5 to 15% by mass dilute sulfuric acid or an aqueous solution containing an organic acid. Examples of such organic acids include, formic acid, acetic acid, oxalic acid, citric acid, ascorbic acid, and methionine.

[0253] The cleaning using alkaline permanganate solution can be performed after the cleaning to prevent the silver components dissolved in the etching solution from adhering to and remaining on the printed wiring board, or the cleaning using alkaline permanganate solution can be performed alone instead of the cleaning to prevent the silver components dissolved in the etching solution from adhering to and remaining on the printed wiring board.

[0254] Furthermore, the printed wiring board obtained using the laminate of the present invention can appropriately implement, as needed, the overlay of the circuit pattern, the formation of the solder mask layer, and the nickel / gold plating, nickel / palladium / gold plating, and palladium / gold plating as the final surface treatment of the circuit pattern.

[0255] The semi-additive laminate of the present invention, as described above, enables the manufacture of multilayer printed circuit boards (PCBs) with two sides connected without the use of a vacuum device. These boards exhibit high adhesion on various smooth substrates, excellent design reproducibility, and smooth circuit patterns with a good rectangular cross-sectional shape. Therefore, by using the semi-additive laminate of the present invention, high-density, high-performance PCB substrates and PCBs of various shapes and sizes can be readily provided at low cost, resulting in high industrial applicability in the PCB field. Furthermore, by using the laminate, not only PCBs can be manufactured, but also various components with patterned metal layers on the surface of planar substrates can be manufactured, such as connectors, electromagnetic wave shielding, RFID antennas, and thin-film capacitors.

[0256] Example

[0257] The present invention will now be described in more detail using examples and comparative examples. In the following examples and comparative examples, "parts" and "%" are both mass references.

[0258] [Manufacturing Example 1: Manufacturing of Primer (B-1)]

[0259] In a nitrogen-purged container equipped with a thermometer, a nitrogen inlet tube, and a stirrer, 100 parts by mass of polyester polyol (a polyester polyol obtained by reacting 1,4-cyclohexanediethanol, neopentyl glycol, and adipic acid), 17.6 parts by mass of 2,2-dimethylolpropionic acid, 21.7 parts by mass of 1,4-cyclohexanediethanol, and 106.2 parts by mass of dicyclohexylmethane-4,4'-diisocyanate were reacted in a mixed solvent of 178 parts by mass of methyl ethyl ketone to obtain a urethane prepolymer solution with isocyanate groups at the end.

[0260] Next, 13.3 parts by mass of triethylamine were added to the above urethane prepolymer solution to neutralize the carboxyl groups present in the urethane prepolymer. Then, 380 parts by mass of water were added and stirred thoroughly to obtain an aqueous dispersion of the urethane prepolymer.

[0261] To the aqueous dispersion of the urethane prepolymer obtained above, 8.8 parts by mass of a 25% by mass ethylenediamine aqueous solution were added and stirred to extend the chain of the urethane prepolymer. Next, aging and desolventizing were performed to obtain an aqueous dispersion of urethane resin (30% by mass of non-volatile components). The weight-average molecular weight of the above urethane resin is 53,000.

[0262] Next, 140 parts by mass of deionized water and 100 parts by mass of the aqueous dispersion of the urethane resin obtained above were added to a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet pipe, a thermometer, a dropping funnel for adding the monomer mixture, and a dropping funnel for adding the polymerization catalyst. The temperature was raised to 80°C while nitrogen was being introduced. Then, while stirring and maintaining the temperature inside the reaction vessel at 80°C, a monomer mixture consisting of 60 parts by mass of methyl methacrylate, 30 parts by mass of n-butyl acrylate, and 10 parts by mass of N-n-butoxymethacrylamide, along with 20 parts by mass of a 0.5% by mass ammonium persulfate aqueous solution, were added dropwise from different dropping funnels over 120 minutes.

[0263] After the addition was complete, the mixture was stirred for another 60 minutes at the same temperature. The temperature inside the reaction vessel was then cooled to 40°C. The mixture was diluted with deionized water to a non-volatile content of 20% by mass, and then filtered through a 200-mesh filter cloth. This yielded an aqueous dispersion of a core-shell composite resin, i.e., a primer layer resin composition, with the aforementioned urethane resin as the shell layer and an acrylic resin such as methyl methacrylate as the core layer. Next, isopropanol and deionized water were added to this aqueous dispersion at a mass ratio of 7 / 3 (isopropanol to water) and a non-volatile content of 2% by mass, and mixed to obtain primer (B-1).

[0264] [Manufacturing Example 2: Manufacturing of Primer (B-2)]

[0265] In a reaction flask equipped with a reflux condenser, thermometer, and stirrer, 200 parts by weight of water and 350 parts by weight of methanol were added to 600 parts by weight of formalin containing 37% by weight of formaldehyde and 7% by weight of methanol. Next, 25% by weight of sodium hydroxide aqueous solution was added to the aqueous solution to adjust the pH to 10, and then 310 parts by weight of melamine was added. The liquid temperature was raised to 85°C, and a hydroxymethylation reaction was carried out for 1 hour.

[0266] Then, formic acid was added and the pH was adjusted to 7, followed by cooling to 60°C to allow for etherification (a second-order reaction). At a turbidity temperature of 40°C, a 25% by mass sodium hydroxide aqueous solution was added to adjust the pH to 9, stopping the etherification reaction (reaction time: 1 hour). Residual methanol was removed under reduced pressure at 50°C (methanol removal time: 4 hours) to obtain a primer resin composition containing melamine resin with 80% by mass of non-volatile components. Next, methyl ethyl ketone was added to this resin composition for dilution and mixing, thereby obtaining a primer (B-2) with 2% by mass of non-volatile components.

[0267] [Manufacturing Example 3: Manufacturing of Primer (B-3)]

[0268] In a reaction vessel equipped with a thermometer, a nitrogen inlet tube, a stirrer, and purged with nitrogen, 9.2 parts by mass of 2,2-dimethylolpropionic acid, 57.4 parts by mass of polymethylene polyphenyl polyisocyanate (Millionate MR-200 manufactured by Tosoh Corporation), and 233 parts by mass of methyl ethyl ketone were added, and the reaction was carried out at 70°C for 6 hours to obtain an isocyanate compound. Next, 26.4 parts by mass of phenol were supplied to the reaction vessel as a capping agent, and the reaction was carried out at 70°C for 6 hours. Then, the mixture was cooled to 40°C to obtain a solution of capped isocyanate.

[0269] Next, 7 parts by mass of triethylamine were added to the obtained isocyanate solution at 40°C to neutralize the carboxyl groups of the isocyanate. Water was added and the mixture was stirred thoroughly. Methyl ethyl ketone was then removed by distillation to obtain a primer resin composition containing 20% ​​by mass of non-volatile components, which is composed of isocyanate and water. Methyl ethyl ketone was then added to this resin composition for dilution and mixing to obtain a primer (B-3) with 2% by mass of non-volatile components.

[0270] [Manufacturing Example 4: Manufacturing of Primer (B-4)]

[0271] 35 parts by weight of phenolic varnish resin (PHENOLITE TD-2131 manufactured by DIC Corporation, hydroxyl equivalent 104 g / equivalent), 64 parts by weight of epoxy resin (EPICLON 850-S manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g / equivalent), and 1 part by weight of 2,4-diamino-6-vinyl-triazine (VT manufactured by Shikoku Kasei Corporation) were mixed and diluted with methyl ethyl ketone to a non-volatile component of 2% by weight to obtain primer (B-4).

[0272] [Manufacturing Example 5: Manufacturing of Primer (B-5)]

[0273] 35 parts by weight of phenolic varnish resin (PHENOLITE TD-2131 manufactured by DIC Corporation, hydroxyl equivalent 104 g / equivalent), 64 parts by weight of epoxy resin (EPICLON 850-S manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g / equivalent), and 1 part by weight of silane coupling agent with triazine ring (VD-5 manufactured by Shikoku Kasei Corporation) were mixed and diluted with methyl ethyl ketone to a non-volatile component of 2% by weight to obtain primer (B-5).

[0274] [Manufacturing Example 6: Manufacturing of Primer (B-6)]

[0275] In a flask equipped with a thermometer, condenser, fractionating tube, and stirrer, 750 parts by weight of phenol, 75 parts by weight of melamine, 346 parts by weight of 41.5% formalin, and 1.5 parts by weight of triethylamine were added. The mixture was heated to 100°C while simultaneously monitoring for exothermic reaction. After reacting at 100°C under reflux for 2 hours, water was removed under normal pressure, and the temperature was raised to 180°C for another 2 hours. Unreacted phenol was then removed under reduced pressure to obtain an aminotriazine-modified phenolic varnish resin. The hydroxyl equivalent was 120 g / equivalent.

[0276] The above-obtained aminotriazine phenolic varnish resin was mixed with 35 parts by weight of epoxy resin (“EPICLON 850-S” manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g / equivalent), and then diluted with methyl ethyl ketone to a non-volatile component of 2% by weight, thereby obtaining the primer composition (B-6).

[0277] [Manufacturing Example 7: Manufacturing of Primer (B-7)]

[0278] The aminotriazine phenolic varnish resin obtained in Manufacturing Example 6 was mixed with 52 parts by weight of epoxy resin (“EPICLON 850-S” manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g / equivalent), and then diluted with methyl ethyl ketone to a non-volatile component of 2% by weight, thereby obtaining the primer composition (B-7).

[0279] [Manufacturing Example 8: Manufacturing of Primer (B-8)]

[0280] By changing the amounts of aminotriazine phenolic varnish resin and epoxy resin from 48 parts by mass to 39 parts by mass and from 52 parts by mass to 61 parts by mass, respectively, a primer composition (B-8) with 2% by mass of non-volatile components was obtained in the same manner as in Manufacturing Example 78.

[0281] [Manufacturing Example 9: Manufacturing of Primer (B-9)]

[0282] By changing the amounts of aminotriazine phenolic varnish resin and epoxy resin from 48 parts by mass to 31 parts by mass and from 52 parts by mass to 69 parts by mass, respectively, a primer composition (B-9) with 2% by mass of non-volatile components was obtained in the same manner as in Manufacturing Example 8.

[0283] [Manufacturing Example 10: Manufacturing of Primer (B-10)]

[0284] In manufacturing example 7, 47 parts by weight of aminotriazine phenolic varnish resin and 52 parts by weight of epoxy resin (“EPICLON 850-S” manufactured by DIC Corporation; bisphenol A type epoxy resin, epoxy equivalent 188 g / equivalent) were further mixed with 1 part by weight of trimellitic anhydride, and then diluted and mixed with methyl ethyl ketone to a non-volatile component of 2% by weight, thereby obtaining primer (B-10).

[0285] [Manufacturing Example 11: Manufacturing of Primer (B-11)]

[0286] In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet pipe, thermometer, and dropping funnel, add 350 parts by weight of deionized water and 4 parts by weight of surfactant ("Latemul E-118B" manufactured by Kao Corporation: 25% by weight of active ingredient), and heat to 70°C while blowing in nitrogen.

[0287] Under stirring, a portion (5 parts by mass) of a monomer pre-emulsion obtained by mixing a vinyl monomer mixture, a surfactant ("Aqualon KH-1025" manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.: 25% by mass of active ingredient) 4 parts by mass and 15 parts by mass of deionized water was added to the reaction vessel. Then, 0.1 parts by mass of potassium persulfate was added. Polymerization was carried out for 60 minutes while maintaining the temperature inside the reaction vessel at 70°C. The vinyl monomer mixture was composed of 47.0 parts by mass of methyl methacrylate, 5.0 parts by mass of glycidyl methacrylate, 45.0 parts by mass of n-butyl acrylate and 3.0 parts by mass of methacrylic acid.

[0288] Next, while maintaining the temperature inside the reaction vessel at 70°C, the remaining monomer pre-emulsion (114 parts by mass) and 30 parts by mass of an aqueous solution of potassium persulfate (1.0% by mass of active ingredient) were added dropwise over 180 minutes using different dropping funnels. After the addition was completed, the mixture was stirred at the same temperature for 60 minutes.

[0289] The temperature inside the reaction vessel was cooled to 40°C, and then deionized water was used to achieve a non-volatile component content of 10.0% by mass. The mixture was then filtered through a 200-mesh filter cloth to obtain the primer resin composition used in this invention. Next, water was added to the resin composition for dilution and mixing to obtain a primer (B-11) with a non-volatile component content of 5% by mass.

[0290] [Preparation Example 1: Preparation of Silver Particle Dispersion]

[0291] In a mixed solvent of 45 parts by mass of ethylene glycol and 55 parts by mass of deionized water, a compound formed by the addition of p-ethyleneimine to polyethylene oxide was used as a dispersant to disperse silver particles with an average particle size of 30 nm, thereby preparing a dispersion containing silver particles and a dispersant. Next, deionized water, ethanol, and a surfactant were added to the obtained dispersion to prepare a 5% by mass silver particle dispersion.

[0292] [Preparation Example 2: Preparation of Copper Etching Solution]

[0293] A copper etching solution was prepared by mixing sulfuric acid (37.5 g / L) and hydrogen peroxide (13.5 g / L) in ion-exchanged water.

[0294] [Preparation Example 3: Preparation of Etching Solution for Silver]

[0295] Add 2.6 parts by mass of acetic acid to 47.4 parts by mass of water, and further add 50 parts by mass of 35% hydrogen peroxide solution to prepare silver etching solution (1). The molar ratio of hydrogen peroxide to carboxylic acid (hydrogen peroxide / carboxylic acid) in the silver etching solution (1) is 13.6, and the content ratio of the mixture of hydrogen peroxide and carboxylic acid in the silver etching solution (1) is 22.4% by mass.

[0296] [Preparation Example 4: Preparation of Conductive Polymer Dispersion]

[0297] Based on patent literature (Japanese Patent Application Publication No. 2003-231991), polypyrrole / polyvinylpyrrolidone (PPy / PVP(SO4)3) doped with sulfate ions was synthesized. 2- )) Colloid. Sodium sulfate is used as a dopant, ammonium persulfate as an oxidant, and polyvinylpyrrolidone as a surfactant. Pyrrole is used as a monomer.

[0298] 0.85 g of PVP (polyvinylpyrrolidone, manufactured by Wako Pure Chemical Industries, Ltd., premium grade) was dissolved in 500 ml of warm water at 40°C. 7.0 g of ammonium persulfate as an oxidant and 32.2 g of sodium sulfate as a dopant were added to the obtained solution, followed by the addition of water to obtain a total aqueous solution of 1 L. 5 mL of pyrrole (manufactured by Tokyo Chemical Industry Co., Ltd., premium grade) was added to the obtained aqueous solution, and the mixture was stirred at room temperature for approximately 12 hours to carry out chemical oxidative polymerization, thereby obtaining a polymerization reaction mixture. Centrifugation was performed to obtain a black aggregate. The obtained aggregate was washed several times with water and redispersed in 50 ml of water to obtain a 10 g / L (PPy / PVP(SO4)2) solution. 2- Aqueous colloidal solution.

[0299] [Example 1]

[0300] A copper circuit pattern with comb-shaped electrodes of L / S = 100 / 100μm and 5mm square pads at the ends is fabricated using a glass epoxy substrate (panasonic's "Multilayer Substrate Material R-1766"; thickness 0.8mm) with 12μm thick copper foil laminated on both sides. Figure 5 ).

[0301] (Semi-additive method for manufacturing laminates)

[0302] (Example 1)

[0303] The glass epoxy material with comb-shaped electrodes and pad patterns fabricated in Example 1 is further heat-pressed (170°C, 60 minutes) with a polyimide film (Upilex 50S manufactured by Ube Industries, Ltd.) placed on it. The polyimide film is then peeled off, thereby fabricating a substrate on which the cured prepreg (insulating layer (A)) is laminated on a glass epoxy material (insulating material) having a conductor circuit layer (CM2).

[0304] On the surface of the cured prepreg (insulating layer (A); prepreg (R-1661 manufactured by Panasonic Corporation, 100 μm thick)) on the aforementioned glass epoxy material, the silver particle dispersion obtained in Preparation Example 1 was coated with a dried silver particle layer (M1) to a thickness of 0.5 g / m using a benchtop miniature coating machine (K Printing Proofer manufactured by RK Print Coat Instruments). 2 The coating was applied in the manner described above. Next, it was dried using a hot air dryer at 160°C for 5 minutes. Further, the film was flipped over, and the silver particle dispersion obtained in Preparation Example 1 was coated as a silver particle layer (M1) with a density of 0.5 g / m². 2 The coating was applied using a hot air dryer at 160°C for 5 minutes, thereby forming a silver particle layer (M1) on the prepreg (insulating layer (A)) on both cured surfaces. The resulting film substrate was then fired at 250°C for 5 minutes, and the conductivity of the silver particle layer was confirmed using a testing machine.

[0305] The glass epoxy board with conductive silver particle layers on both surfaces obtained above is immersed in an electroless copper plating solution (Circuposit 6550 manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at 35°C for 10 minutes to form an electroless copper plating film (M2; thickness 0.2μm) on both surfaces. This creates a semi-additive laminate in which a conductive silver particle layer (M1) and a 0.2μm thick copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate. The inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0306] (Example 2)

[0307] The immersion time in the electroless copper plating solution was changed from 10 minutes to 25 minutes. Otherwise, the same procedure as in Example 1 was followed to form a 0.5 μm thick electroless copper plating film on the silver particle layer (M1). This produced a semi-additive laminate in which a conductive silver particle layer (M1) and a 0.5 μm copper layer (M2) were sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate. The inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0308] (Example 3)

[0309] A laminate containing a conductive silver particle layer (M1) and a 0.2 μm thick copper layer formed on the surface of the prepreg (insulating layer (A)) cured on the glass epoxy material as prepared in Example 1 was fixed to a copper frame. An electroless copper plating layer was placed at the cathode, and phosphorus-containing copper was used as the anode. An electrolytic plating solution containing copper sulfate (copper sulfate 60 g / L, sulfuric acid 190 g / L, chloride ions 50 mg / L, additive (Copper Gleam ST-901 manufactured by Rohm and Haas Electronic Materials Co., Ltd.)) was used at a current density of 2 A / dm³. 2 Electroplating is performed for 4 minutes to produce a semi-additive laminate in which a conductive silver particle layer (M1) and a 2μm copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, wherein the inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0310] (Example 4)

[0311] The dried silver particle layer was reduced from 0.5 g / m 2 Change to 0.8g / m 2 In addition, the same procedure as in Example 1 was followed, and a conductive silver particle layer (M1) was formed on the surface of the prepreg (insulation layer (A)) on both sides of the glass epoxy material after curing. The mixture was then fired at 250°C for 5 minutes, and the conductivity of the silver particle layer was confirmed by a testing machine. For the substrate with conductive silver particle layers on both surfaces obtained in this way, the surface of the silver particle layer is placed as the cathode, and phosphorus copper is used as the anode. Electrolytic plating solution containing copper sulfate (copper sulfate 60g / L, sulfuric acid 190g / L, chloride ion 50mg / L, additive (Copper Gleam ST-901 manufactured by Rohm and Haas Electronic Materials Co., Ltd.)) is used for electrolytic plating at a current density of 2A / dm2 for 4.5 minutes. This produces a semi-additive laminate in which a conductive silver particle layer (M1) and a 2μm copper layer (M2) are sequentially stacked on the surface of the insulating layer (A) stacked on the inner layer printed wiring substrate. The inner layer printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0312] (Example 5)

[0313] Similar to Example 1, the double-sided overlapping prepreg (insulating layer (A)) of the glass epoxy material with comb-shaped electrodes and pad patterns prepared in Example 1 was further heat-pressed (170°C, 60 minutes) while a polyimide film ("Upilex 50S" manufactured by Ube Industries, Ltd.) was placed on it, and the polyimide film was peeled off, thereby creating a substrate on which the cured prepreg (insulating layer (A)) is laminated on the glass epoxy material (insulating material) having a conductor circuit layer (CM2).

[0314] On the surface of the cured prepreg (insulation layer (A)) on the aforementioned glass epoxy material, the primer (B-1) obtained in Manufacturing Example 1 was applied to a thickness of 120 nm after drying using a benchtop small coating machine (“K Printing Proofer” manufactured by RK Print Coat Instruments). The coating was then dried at 80°C for 5 minutes using a hot air dryer. Furthermore, the substrate was flipped over, and the primer (B-1) obtained in Manufacturing Example 1 was applied to a thickness of 120 nm after drying, and dried at 80°C for 5 minutes using a hot air dryer. This formed a primer layer on the cured prepreg (insulation layer (A)) on both surfaces.

[0315] Using the substrate with a primer layer formed on the prepreg (insulating layer (A)) on both cured surfaces obtained above, except that, in the same manner as in Example 2, an electroless copper plating film with a thickness of 0.5 μm is formed on the conductive silver particle layer (M1), thereby producing a semi-additive laminate in which a primer layer (B), a conductive silver particle layer (M1) and a 0.5 μm copper layer (M2) are sequentially stacked on the surface of the insulating layer (A) stacked on the inner layer printed wiring substrate, wherein the inner layer printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0316] (Example 6)

[0317] In Example 5, the silver particle layer was increased from 0.5 g / m². 2 Change to 0.8g / m 2 Electrolytic copper plating is performed in the same manner as in Example 4, thereby producing a semi-additive laminate in which a primer layer (B), a conductive silver particle layer (M1), and a 0.5 μm thick copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, wherein the inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0318] (Examples 7-16)

[0319] The type of primer used for the primer layer (B) and its drying conditions, and the amount of silver in the silver particle layer (M1) are changed as shown in Table 1 or 2. Otherwise, the same procedure is followed as in Example 6 to produce a semi-additive laminate in which the primer layer (B), the conductive silver particle layer (M1), and the copper layer (M2) are sequentially laminated on the surface of the insulating layer (A) laminated on the inner layer printed wiring substrate, wherein the inner layer printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material.

[0320] (Example 17)

[0321] The laminate prepared in Example 2 consists of a conductive silver particle layer (M1) and a 0.5 μm copper layer (M2) sequentially laminated on the surface of an insulating layer (A) laminated on an inner printed wiring substrate. The inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material, and a 70 μm diameter via is formed at the pad position of the inner conductor circuit layer (CM2) using a laser to connect to the inner conductor circuit layer (CM2).

[0322] The substrate thus obtained with vias connected to the inner conductor circuit layer (CM2) is subjected to a black hole process (through-carbon adsorption treatment-etching) by MacDermid to attach carbon to the surface of the vias. The copper layer (M2) with attached carbon is removed by etching using the sulfuric acid / hydrogen peroxide aqueous solution prepared in Preparation Example 2, thereby exposing the conductive silver particle layer (M1) on the insulating layer (A). A semi-additive laminate is thus obtained, which has a conductive silver particle layer (M1) on the surface of the insulating layer (A) laminated on the inner printed wiring substrate, wherein the inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material; further, it has vias extending from the insulating layer (A) to the conductor circuit layer (CM2), and the surface of the vias is ensured to be conductive by carbon.

[0323] (Example 18)

[0324] Using the laminate prepared in Example 6 instead of the laminate prepared in Example 2, except that the same procedure is followed as in Example 17, a semi-additive laminate is obtained, which has a conductive silver particle layer (M1) on the surface of an insulating layer (A) laminated on an inner printed wiring substrate, wherein a conductor circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate; further having vias from the insulating layer (A) to the conductor circuit layer (CM2), and the surface of the vias is ensured to be conductive by carbon.

[0325] (Example 19)

[0326] Using the laminate prepared in Example 11 instead of the laminate prepared in Example 2, except that the same operation is performed as in Example 17, a semi-additive laminate is obtained, which has a conductive silver particle layer (M1) on the surface of an insulating layer (A) laminated on an inner printed wiring substrate, wherein a conductor circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate; further having vias from the insulating layer (A) to the conductor circuit layer (CM2), and the surface of the vias is ensured to be conductive by carbon.

[0327] (Example 20)

[0328] Similar to Example 19, a stack of conductive silver particles (M1) and a 0.5 μm copper layer (M2) is sequentially stacked on the surface of an insulating layer (A) on an inner printed wiring substrate on which a conductor circuit layer (CM2) is formed on an insulating material. At the pad position of the inner conductor circuit layer (CM2), a 70 μm diameter via is formed using a laser to connect to the inner conductor circuit layer (CM2).

[0329] The substrate thus obtained, with vias connected to the inner conductive circuit layer (CM2), is immersed in a catalyst solution containing 1 g / L palladium chloride, 1 ml / L hydrochloric acid, and 1 g / L dimethylthiourea at 25°C for 3 minutes, instead of performing a black hole process. Next, the substrate is washed with water and treated at 50°C for 2 minutes with a reducing solution containing 10 g / L dimethylamine borane and 5 g / L sodium hydroxide, using palladium to make the surface of the vias conductive, thereby obtaining a semi-additive laminate having a conductive silver particle layer (M1) on the surface of an insulating layer (A) stacked on the inner printed wiring substrate, wherein the inner printed wiring substrate has a conductive circuit layer (CM2) formed on the insulating material; further, it has vias extending from the insulating layer (A) to the conductive circuit layer (CM2), and the surface of the vias is ensured to be conductive by palladium.

[0330] (Example 21)

[0331] In Example 20, a substrate with vias connected to the inner conductor circuit layer (CM2) was fabricated in Preparation Example 4 using a PPy / PVP(SO4) substrate. 2-Immersing the via in an aqueous colloidal solution at room temperature for 2 minutes allows colloidal particles to adhere to the surface of the via. A conductive polymer is then used to make the surface of the via conductive, instead of using palladium for conductivity. This yields a semi-additive laminate having a conductive silver particle layer (M1) on the surface of an insulating layer (A) laminated on an inner printed wiring substrate. The inner printed wiring substrate has a conductor circuit layer (CM2) formed on the insulating material. Furthermore, it has vias leading from the insulating layer (A) to the conductor circuit layer (CM2), and the surface of the vias is ensured to be conductive by a conductive polymer.

[0332] (Manufacturing of printed circuit boards)

[0333] (Examples 22-26)

[0334] Using the semi-additive laminate prepared in Examples 17-21, a dry film resist (Photec RD-1225 manufactured by Hitachi Chemical Co., Ltd.; resist film thickness 25 μm) was laminated onto the silver particle layer (M1) using a roller laminator at 100°C. Then, using a direct exposure digital imaging device (Nuvogo1000R manufactured by Orbotech), as shown in Figure *, a TEG pattern of a conductive circuit layer (CM1) with a 200 μm diameter pad surface, a 50 μm width from the pad surface, and a 5 cm length was exposed in the via portion connected to the pad portion of the inner conductor circuit (CM2). Next, development was performed using a 1% (w / w) sodium carbonate aqueous solution, thereby exposing the silver particle layer (M1) of the aforementioned TEG pattern.

[0335] Next, a silver particle layer (M1) of a substrate with a patterned resist is placed on the cathode, and a phosphorus-containing copper plating solution is used as the anode. An electrolytic plating solution containing copper sulfate (copper sulfate 60 g / L, sulfuric acid 190 g / L, chloride ions 50 mg / L, additive (Copper Gleam ST-901 manufactured by Rohm and Haas Electronic Materials Co., Ltd.)) is applied at a current density of 2 A / dm³. 2 Electroplating was performed for 27 minutes, thereby forming a 12 μm thick conductive circuit layer (CM1) on the TEG patterned area where the resist was removed by electroplating copper. Next, these substrates were immersed in a 3% by mass sodium hydroxide aqueous solution set at 50°C, thereby stripping the pattern resist.

[0336] Next, the substrate obtained above was immersed in the silver etching solution obtained in Preparation Example 2 at 25°C for 30 seconds to remove the silver particle layer (M1) outside the conductive circuit layer pattern, thereby obtaining a printed wiring board. Regarding the cross-sectional shape of the conductive circuit layer of the fabricated printed wiring board, the individual wiring height and wiring width were not reduced, and it exhibited a rectangular shape without undercut, and was a conductive circuit layer (CM1) with a smooth surface.

[0337] (Comparative Example 1)

[0338] In Example 1, the aforementioned prepreg and a 12 μm thick rolled copper foil (BHY-82F-HA-V2) manufactured by JX Metal Co., Ltd. were overlapped on both sides of the glass epoxy material prepared in Example 1 and hot-pressed (170°C, 60 minutes) to replace the formation of a silver particle layer on the surface of the cured prepreg (insulating layer (A); prepreg (R-1661 manufactured by Panasonic Corporation, 100 μm thick)) on the glass epoxy material. This resulted in the fabrication of a substrate on which the cured prepreg (insulating layer (A)) and copper foil were stacked on a glass epoxy material (insulating material) having a conductive circuit layer (CM2). Using the sulfuric acid / hydrogen peroxide-based copper etching solution prepared in Example 2, the copper foil on the surface of the substrate was etched to 3 μm. Then, in the same manner as in Examples 22-26, a 12 μm thick conductive circuit layer was formed on the copper foil plating substrate using copper.

[0339] Next, the copper seed crystal was removed by immersion in a sulfuric acid / hydrogen peroxide-based flash etching solution used in the copper seed etching process. As a result, the conductive circuit layer was etched, the film thickness decreased by about 3 μm, the wiring width decreased by about 6 μm, and the cross-sectional shape could no longer maintain a rectangle but became a "trapezoidal" shape. In addition, the surface of the copper conductive layer became rough due to etching, and its smoothness was reduced.

[0340] (Comparative Example 2)

[0341] In Comparative Example 1, on a glass epoxy material (insulating material) having a conductive circuit layer (CM2), a copper foil on the surface of a substrate with a layer of cured prepreg (insulating layer (A)) and copper foil was used without etching. The conductive circuit layer was formed by subtractive etching using ferric chloride etching solution. As a result, the cross-sectional shape of the circuit layer could not be kept rectangular and became "trapezoidal". The surface of the copper conductive layer was significantly roughened due to etching.

[0342] [Confirmation of the presence or absence of undercut and the cross-sectional shape of the wiring section]

[0343] The cross-section of the comb-shaped electrode portion of the printed wiring board obtained above was magnified to 500 to 10,000 times using a scanning electron microscope (JSM7800 manufactured by Nippon Electron Ltd.) to confirm the presence or absence of undercut and the cross-sectional shape of the comb-shaped electrode portion.

[0344] The surface roughness of the printed wiring board was observed using a laser microscope (KEYENCE, VK-9710) to confirm its surface roughness. A surface roughness Rz of 3 μm or less was evaluated as smooth (smoothness: 〇), while a surface roughness Rz greater than 3 μm was evaluated as uneven (smoothness: ×). Furthermore, when the difference between the designed width of the wiring and the width of the upper surface of the formed wiring, caused by the resist used during wiring formation, was 2 μm or less, it was evaluated as lateral etching being suppressed and maintaining a rectangular shape (rectangularity: 〇). A difference greater than 2 μm was evaluated as not maintaining a rectangular shape (rectangularity: ×). Examples, comparative examples, and evaluation results are shown in Tables 1 to 3.

[0345] [Table 1]

[0346]

[0347] [Table 2]

[0348]

[0349] [Table 3]

[0350]

[0351] Symbol Explanation

[0352] 1: Insulating substrate

[0353] 2: Silver Particle Layer (M1)

[0354] 3: Covering layer (copper layer)

[0355] 4: Conductor Circuit Layer (CM2)

[0356] 5: Blind hole

[0357] 6: Palladium, conductive polymers, carbon

[0358] 7: Pattern resist

[0359] 8: Conductive layer (electrolytic copper plating layer)

[0360] (a) Semi-additive method using laminates (the structure of claim 1)

[0361] (b) Process 1: Formation of non-through holes (blind guide holes)

[0362] (c) Process 2: Conducting the blind via

[0363] (d) Process 3: Exposure of the conductive silver particle layer

[0364] (e) Step 4: Pattern Resist Formation

[0365] (f) Step 5: Formation of a conductive layer based on electrolytic copper plating

[0366] (g) Step 6: Stripping the pattern resist

[0367] (h) Step 6: Removal of silver seed crystals (configuration of claim 11)

Claims

1. A laminated body for a semi-additive process, characterized in that, A semi-additive laminate for manufacturing multilayer printed wiring boards, used to electrically connect the conductive circuit layer (CM1) on the surface of a substrate to the conductor circuit layer (CM2) of the inner printed wiring substrate. A conductive silver particle layer (M1) and a copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, wherein the copper layer (M2) has a thickness of 0.1 μm to 2 μm, and a conductive circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate. The copper layer (M2) is a layer that protects the conductivity of the silver particle layer (M1) during the etching process of the printed wiring board manufacturing method, which removes palladium, conductive polymer, and carbon adsorbed outside the inner wall surface of the holes formed in the insulating layer (A), by being stacked on the silver particle layer (M1). The insulating layer (A) has a structure that is connected to the conductor circuit layer (CM2) of the inner printed wiring substrate.

2. The laminated body for the semi-additive method according to claim 1, characterized in that, A primer layer (B) is further provided between the surface (S1) of the insulating layer (A) and the conductive silver particle layer (M1).

3. A laminated body used in a semi-additive process, characterized in that, A semi-additive laminate for manufacturing multilayer printed wiring boards, used to electrically connect the conductive circuit layer (CM1) on the surface of a substrate to the conductor circuit layer (CM2) of the inner printed wiring substrate. A conductive silver particle layer (M1) and a copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, wherein the copper layer (M2) has a thickness of 0.1 μm to 2 μm, and a conductive circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate. Furthermore, it has holes extending from the insulating layer (A) to the conductor circuit layer (CM2). The surface of the pore is a substrate whose conductivity is ensured by any one of palladium, conductive polymer, or carbon. The copper layer (M2) is a layer that protects the conductivity of the silver particle layer (M1) during the etching process of the printed wiring board manufacturing method, which removes palladium, conductive polymer, and carbon adsorbed outside the inner wall surface of the holes formed in the insulating layer (A), by being stacked on the silver particle layer (M1). The insulating layer (A) has a structure that is connected to the conductor circuit layer (CM2) of the inner printed wiring substrate.

4. The laminated body for the semi-additive method according to claim 3, characterized in that, A primer layer (B) is further provided between the insulating layer (A) and the conductive silver particle layer (M1).

5. The semi-addition laminate according to claim 1 or 3, wherein the silver particles constituting the silver particle layer (M1) are coated with a polymeric dispersant.

6. The semi-addition laminate according to claim 2 or 4, wherein the silver particles constituting the silver particle layer (M1) are coated with a polymeric dispersant.

7. The semi-addition laminate according to claim 6, wherein the primer layer (B) is a layer composed of a resin having a reactive functional group [X], the polymeric dispersant has a reactive functional group [Y], and the reactive functional group [X] and the reactive functional group [Y] can form bonds with each other through reaction.

8. The laminate for the semi-addition process according to claim 7, wherein the reactive functional group [Y] is a basic nitrogen atom group.

9. The laminate for the semi-addition process according to claim 7, wherein the polymeric dispersant having the reactive functional group [Y] is one or more selected from the group consisting of polyalkylene imides and polyalkylene imides having a polyoxyethylene unit polyoxyalkylene structure.

10. The laminate for the semi-addition process according to claim 8, wherein the polymeric dispersant having the reactive functional group [Y] is one or more selected from the group consisting of polyalkylene imides and polyalkylene imides having a polyoxyethylene unit polyoxyalkylene structure.

11. The laminate for the semi-addition process according to claim 7, wherein the reactive functional group [X] is selected from one or more of the group consisting of ketone, acetoacetyl, epoxy, carboxyl, N-alkanol, isocyanate, vinyl, (meth)acryloyl, and allyl.

12. A printed wiring board, characterized in that, The laminate is formed using the semi-additive method according to any one of claims 1 to 11.

13. A multilayer printed wiring board, characterized in that, A multilayer printed wiring board is formed by electrically connecting the conductive circuit layer (CM1) on the surface of the substrate and the conductor circuit layer (CM2) on the inner printed wiring substrate. A conductive silver particle layer (M1) and a copper layer (M2) are sequentially stacked on the surface of an insulating layer (A) stacked on an inner printed wiring substrate, wherein the copper layer (M2) has a thickness of 0.1 μm to 2 μm, and a conductive circuit layer (CM2) is formed on the insulating material of the inner printed wiring substrate. Furthermore, it has holes extending from the insulating layer (A) to the conductor circuit layer (CM2). The surface of the hole has a structure in which a conductor circuit layer (CM2) connected to the inner printed wiring substrate is formed by stacking palladium, a conductive polymer, carbon, and a copper layer. The copper layer (M2) is a layer that protects the conductivity of the silver particle layer (M1) during the etching process of the printed wiring board manufacturing method, which removes palladium, conductive polymer, and carbon adsorbed outside the inner wall surface of the holes formed in the insulating layer (A), by being stacked on the silver particle layer (M1).

14. The printed wiring board according to claim 13, characterized in that, A primer layer (B) is further provided between the insulating layer (A) and the silver particle layer (M1).

15. A method for manufacturing a semi-additive laminate, used to manufacture a multilayer printed circuit board according to any one of claims 3 to 11, characterized in that, include: Step 1: A hole is formed in the laminate from the insulating layer (A) to the conductor circuit layer (CM2). The laminate has a conductive silver particle layer (M1) and a copper layer (M2) sequentially stacked on the surface of the insulating layer (A) stacked on the inner layer printed wiring substrate. The copper layer (M2) has a thickness of 0.1μm to 2μm. The conductor circuit layer (CM2) is formed on the insulating material in the inner layer printed wiring substrate. Step 2: Apply palladium, a conductive polymer, or carbon to the surface of a substrate having a hole extending from the insulating layer (A) to the conductive circuit layer (CM2) to make the hole surface conductive. Step 3 involves etching the copper layer (M2) to expose the conductive silver particle layer (M1).

16. The method for manufacturing a semi-additive laminate according to claim 15, characterized in that, A primer layer (B) is further laminated between the insulating layer (A) and the silver particle layer (M1).

17. A method for manufacturing a multilayer printed circuit board according to claim 12, characterized in that, include: Step 1: A hole is formed in the laminate from the insulating layer (A) to the conductor circuit layer (CM2). The laminate has a conductive silver particle layer (M1) and a copper layer (M2) sequentially stacked on the surface of the insulating layer (A) stacked on the inner layer printed wiring substrate. The copper layer (M2) has a thickness of 0.1μm to 2μm. The conductor circuit layer (CM2) is formed on the insulating material in the inner layer printed wiring substrate. Step 2: Apply palladium, a conductive polymer, or carbon to the surface of a substrate having a hole extending from the insulating layer (A) to the conductive circuit layer (CM2) to make the hole surface conductive. Step 3: Etch the copper layer (M2) to expose the conductive silver particle layer (M1); Step 4: A patterned resist is formed on the conductive silver particle layer (application M1); Step 5: Electrolytic copper plating is used to electrically connect the surface layer and the inner layer of the conductor circuit layer (CM2), and a conductive circuit layer (CM1) is formed. Step 6: The pattern resist is stripped off, and the silver particle layer (M1) of the non-conductive circuit pattern formation part is removed using an etching solution.

18. The method for manufacturing a multilayer printed circuit board according to claim 17, characterized in that, A primer layer (B) is further provided between the insulating layer (A) and the silver particle layer (M1).

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