JP2013182714A - Conductive laminate and its manufacturing method and precursor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate which, while securing adhesion with a substrate and a conductive layer, can form a Ni plating layer (especially, a Ni/Au plating layer) on the conductive layer.SOLUTION: An adhesion layer including metal particles and bismuth glass frit of 500°C or less in softening point is formed on a substrate, and then a coating layer including metal nanoparticles and substantially not including bismuth glass frit of 500°C or less in softening point is further formed on the adhesion layer. The metal nanoparticles are about 10 to 100 nm in number-average grain size. The metal nanoparticles may be silver nanoparticles. The surfaces of the metal nanoparticles may be coated with a dispersant. The coating layer may further include metal fillers of 200 nm or more in number-average grain size. The laminate can be calcined at a temperature higher than the softening point of the bismuth glass frit but lower than the heatproof temperature of the substrate to manufacture a conductive laminate having a conductive coating layer formed on the substrate via a conductive adhesion layer. A plating layer (especially, a Ni/Au plating layer) may further be formed on the conductive coating layer.

Description

  The present invention relates to a conductive laminate in which a metal conductive layer containing a bismuth-based glass frit is laminated on a substrate (such as a glass substrate), a manufacturing method thereof, and a precursor thereof.

  In the electronics field, as a conductive paste that can easily form various circuit patterns by printing, etc., a conductive powder that contains a conductive metal powder, a glass powder as a sintering aid, and an organic vehicle as a binder component. Sex pastes are widely used.

For example, Japanese Patent Laid-Open No. 2003-132735 (Patent Document 1) discloses a thick film conductor paste containing a metal powder (A), a glass powder (B), and an organic vehicle (C) which are monodispersed spherical powders. It is disclosed. In this thick film conductor paste, noble metal powder is used as the metal powder, and silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), lead oxide (PbO), calcium oxide (CaO), oxide is used as the glass powder. A glass frit having a softening point of 500 to 650 ° C. containing boron (B ₂ O ₃ ) as a main component is used.

  Such a conductive paste is usually applied on a ceramic substrate according to a circuit pattern composed of predetermined electrodes / wirings by a method such as screen printing. Furthermore, by heating the obtained pattern together with the substrate to a temperature equal to or higher than the softening point of the glass frit, the sintering of the metal powder proceeds, while the softened glass frit joins the sintered metal powder and the substrate. Therefore, a circuit pattern made of a hard metal film is formed on the substrate with adhesion.

  However, in the manufacture of electronic components in which a glass substrate is used instead of a ceramic substrate for the purpose of reducing the cost of the product, etc., since the heat resistant temperature of glass is 600 ° C. or less, a glass frit having a softening point exceeding 600 ° C. is used. The used conductive paste cannot be used. Although it is possible to use a conductive paste using a glass frit having a softening point of about 500 to 600 ° C., at a temperature exceeding 500 ° C., the problem is that the glass substrate is yellowed by diffusion of metal into the glass substrate. There is. Therefore, a bismuth glass frit is selected as a glass frit having a softening point of 500 ° C. or less.

  On the other hand, a glass substrate on which a circuit pattern is formed has a Ni plating (electroless Ni plating) layer and a Ni / Au plating (no plating) on the circuit pattern in order to maintain the adhesion between the glass substrate and the circuit pattern over a long period of time. A plating layer such as an electrolytic Ni / Au plating layer may be provided. However, in a pattern formed using a bismuth glass frit, the resistance to plating solution of the bismuth glass frit is low, so that the circuit pattern is easily dropped during the plating process. Further, since bismuth works as a catalyst poison for Ni / Au plating, formation of the Ni / Au plating layer is hindered. Furthermore, in applications where soldering to circuit patterns is necessary, good solderability cannot be obtained due to the presence of glass frit.

JP 2003-132735 A (Claim 1, paragraphs [0017] [0019])

  Accordingly, an object of the present invention is to provide a conductive laminate capable of forming a Ni plating layer (particularly a Ni / Au plating layer) on a conductive layer while ensuring adhesion between the substrate (particularly a glass substrate) and the conductive layer, and It is in providing the manufacturing method and precursor.

  Another object of the present invention is to provide a conductive laminate that can form a Ni / Au plating layer firmly on a conductive layer even when it contains bismuth-based glass frit, and a method for producing the same and a precursor thereof. .

  Still another object of the present invention is to provide a conductive laminate that can improve solderability even when it contains a bismuth-based glass frit, a method for producing the same, and a precursor thereof.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have formed an adhesive layer containing metal particles and a bismuth-based glass frit having a softening point of 500 ° C. or lower on a substrate (particularly a glass substrate). On this adhesive layer, by forming a coating layer containing metal nanoparticles and substantially free of bismuth glass frit having a softening point of 500 ° C. or less, adhesion between the substrate and the conductive layer is ensured. The inventors have found that a Ni plating layer (particularly a Ni / Au plating layer) can be formed on the conductive layer, and completed the present invention.

  That is, the laminate of the present invention is a laminate in which a coating layer is formed on a substrate via an adhesive layer, and the adhesive layer is composed of metal particles and a bismuth glass frit having a softening point of 500 ° C. or less. And the coating layer contains metal nanoparticles and does not substantially contain a bismuth glass frit having a softening point of 500 ° C. or lower. The number average particle diameter of the metal nanoparticles is about 10 to 100 nm. The metal nanoparticles may be conductive metal nanoparticles (particularly silver nanoparticles). The surface of the metal nanoparticles may be coated with a dispersant. The coating layer further includes a metal filler having a number average particle diameter of 200 nm or more, and a ratio (mass ratio) between the metal nanoparticles and the metal filler is about metal nanoparticles / metal filler = 30/70 to 99/1. The ratio of the number average particle diameter may be about metal nanoparticles / metal filler = 1/1000 to 1/5. The coating layer may further contain a dispersion medium and / or a binder resin. The said adhesive layer may contain 10-50 mass parts of bismuth-type glass frit with respect to 100 mass parts of metal particles. The adhesive layer may further contain a dispersion medium and / or a binder resin, and the metal particles may contain silver nanoparticles and a silver filler. The average thickness ratio between the adhesive layer and the cover layer is approximately adhesive layer / cover layer = 50/50 to 5/95. The substrate may be a glass substrate.

  In the present invention, the laminate is fired at a temperature not lower than the softening point of the bismuth-based glass frit and not higher than the heat resistance temperature of the substrate, and a conductive coating layer is formed on the substrate via the conductive adhesive layer. A method for producing a conductive laminate is also included. In this method, a plating layer may be further formed on the conductive coating layer. The plating layer may be a Ni / Au plating layer.

  The present invention also includes a conductive laminate obtained by the above method. In the conductive laminate of the present invention, the porosity of the conductive coating layer may be 2% or less. A Ni / Au plating layer may be further formed on the conductive coating layer. Furthermore, the present invention provides a laminate in which a conductive coating layer formed of silver is formed on a substrate via a conductive adhesive layer formed of silver and a bismuth glass frit having a softening point of 500 ° C. or lower. And the electroconductive laminated body whose porosity of the said conductive coating layer is 5% or less is also contained.

  In the present invention, after forming an adhesive layer containing metal particles and a bismuth-based glass frit having a softening point of 500 ° C. or less on a substrate (particularly a glass substrate), metal nanoparticles are further included on the adhesive layer, In addition, since the coating layer that is substantially free of bismuth-based glass frit having a softening point of 500 ° C. or less (particularly not completely included) is formed, the conductive layer is secured while ensuring the adhesion between the substrate and the conductive layer. A Ni plating layer (particularly a Ni / Au plating layer) can be formed on the substrate. In particular, since the coating layer is formed, even if bismuth glass frit is included, bismuth does not act as a catalyst poison for Ni / Au plating, and the Ni / Au plating layer is firmly formed on the conductive layer. Can be formed. Furthermore, solderability can be improved even if bismuth-based glass frit is included.

FIG. 1 is a scanning electron microscope (SEM) photograph of the surface of the conductive coating layer of the conductive laminate obtained in Example 2. FIG. 2 is an SEM photograph of the surface of the conductive coating layer of the conductive laminate obtained in Example 3. FIG. 3 is an SEM photograph of the surface of the conductive coating layer of the conductive laminate obtained in Comparative Example 2.

  The laminate of the present invention has a coating layer formed on a substrate via an adhesive layer, and is a precursor of a conductive laminate.

[substrate]
The substrate is not particularly limited as long as it can be fired, and various materials such as semiconductors (ceramics such as silica and alumina), inorganic materials such as glass and metal, and organic materials such as engineering plastics are used. it can. In the present invention, among these substrates, it is used for a material having low heat resistance, and the substrate has a heat resistant temperature (or softening point) of about 600 ° C. or less, and may be, for example, about 520 to 580 ° C.

  Of these substrates, a glass substrate is preferable because it has excellent adhesion to an adhesive layer containing a bismuth-based glass frit. Examples of the glass substrate include soda glass, borosilicate glass, crown glass, barium-containing glass, strontium-containing glass, boron-containing glass, low alkali glass, alkali-free glass, crystallized transparent glass, silica glass, quartz glass, and heat-resistant glass. For example, a substrate formed by the above method. Among these glass substrates, alkali glass substrates such as soda glass are widely used.

  The surface of the substrate is subjected to oxidation treatment [surface oxidation treatment, for example, discharge treatment (corona discharge treatment, glow discharge, etc.), acid treatment (chromic acid treatment, etc.), ultraviolet irradiation treatment, wrinkle treatment, etc., surface unevenness treatment (solvent treatment) Surface treatment such as sand blasting).

  What is necessary is just to select the thickness of a board | substrate suitably according to a use, for example, 0.001-10 mm, Preferably it is 0.01-5 mm, More preferably, it is about 0.05-3 mm (especially 0.1-1 mm). May be.

[Adhesive layer]
The adhesive layer includes metal particles and a bismuth-based glass frit having a softening point of 500 ° C. or less, and the adhesive layer usually includes a conductive paste (first conductive paste) including the metal particles and the bismuth-based glass frit as a substrate. It is formed by coating on the top.

(Metal particles)
Examples of the metal (metal atom) constituting the metal particles include transition metals (for example, periodic table group 4A metals such as titanium and zirconium; periodic table group 5A metals such as vanadium and niobium; periodic periods such as molybdenum and tungsten). Table 6A metal; Periodic table such as manganese Group 7A metal; Periodic table Group 8 metal such as iron, nickel, cobalt, ruthenium, rhodium, palladium, rhenium, iridium, platinum; Period such as copper, silver, gold Table 1B metal etc., Periodic table 2B metal (eg zinc, cadmium etc.), Periodic table group 3B metal (eg aluminum, gallium, indium etc.), Periodic table group 4B metal (eg germanium) , Tin, lead, etc.) and periodic table Group 5B metals (eg, antimony, bismuth, etc.). These metals can be used alone or in combination of two or more, and may be an alloy. Among these metals, from the viewpoint of conductivity, Group 8 metal of the periodic table (iron, nickel, rhodium, palladium, platinum, etc.), Group 1B metal of the periodic table (copper, silver, gold, etc.), periodic table Group 3B metals (such as aluminum) and periodic table Group 4B metals (such as tin) are widely used, and conductive metals, particularly silver, are preferred.

  The metal particles preferably include metal nanoparticles, and a combination of metal nanoparticles and metal fillers is particularly preferable. The metal constituting the metal nanoparticles and the metal constituting the metal filler may be different, but are preferably the same or the same group metals (particularly the same metal) from the viewpoint of easy sintering.

(1) Metal nanoparticle The metal nanoparticle may have a nanometer size. Specifically, the number average particle size (number average primary particle size) is less than about 200 nm, for example, 5 to 150 nm, Preferably it is about 10-120 nm, More preferably, it is about 20-100 nm (especially 30-80 nm). The maximum primary particle size of the metal nanoparticles may be, for example, less than 200 nm, preferably 50 to 190 nm, and more preferably about 100 to 180 nm. If the particle size of the metal nanoparticles is too large, the sinterability is lowered, and if it is too small, the production of the nanoparticles becomes difficult.

  In the present specification, the number average particle diameter can be measured using a transmission electron microscope (TEM).

  The metal nanoparticles are usually used in combination with a dispersant, and in particular, the surface of the metal nanoparticles may be coated with the dispersant. As the dispersant, for example, a compound having at least one functional group selected from the group consisting of a group having a nitrogen atom, a hydroxyl group and a carboxyl group is preferable.

  The ratio of a dispersing agent is 0.1-30 mass parts with respect to 100 mass parts of metal nanoparticles in conversion of solid content, Preferably it is 0.5-20 mass parts, More preferably, it is 1-15 mass parts ( In particular, it is about 1.5 to 10 parts by mass. When the proportion of the dispersant is too small, the operability of the paste is lowered, and when too large, the conductivity of the sintered film is lowered.

(2) Metal filler The metal filler (powder), when combined with the metal nanoparticles, can impart fluidity to the paste and improve the conductivity of the sintered film.

  The number average particle size (number average primary particle size) of the metal filler may be 200 nm or more (for example, about 0.2 to 10 μm), for example, 0.2 to 5 μm, preferably 0.3 to 2 μm, The thickness is preferably about 0.4 to 1.5 μm (particularly 0.5 to 1 μm). The particle size range of the metal filler may be, for example, about 0.2 to 30 μm, preferably 0.3 to 20 μm, more preferably about 0.4 to 10 μm (particularly 0.5 to 5 μm). When the particle size of the metal filler is too large, for example, clogging is likely to occur in screen printing or the like. On the other hand, if the particle size is too small, the dispersibility of the metal filler is lowered, so that the amount of dispersant used increases and the amount of gas generated during firing also increases.

  The ratio of the average particle diameter (number average particle diameter) between the metal nanoparticles and the metal filler is as follows: metal nanoparticles / metal filler = 1/1000 to 1/5, preferably 1/500 to 1/10 (for example, 1 / 300 to 1/20), more preferably 1/200 to 1/30 (particularly 1/100 to 1/40). When the ratio between the two is in this range, the filling efficiency of the metal nanoparticles and the metal filler is improved, so that the conductivity of the fired film can be improved.

  The ratio of the metal filler is, for example, about 10 to 1000 parts by mass, preferably 30 to 500 parts by mass, and more preferably about 50 to 300 parts by mass (particularly 100 to 250 parts by mass) with respect to 100 parts by mass of the metal nanoparticles. is there. If the ratio between the two is in this range, the sintering of the two is densely performed, so that the conductivity of the fired film can be improved.

(Bismuth glass frit)
In the present invention, by using a bismuth glass frit having a softening point of 500 ° C. or less, even if the substrate has low heat resistance such as a glass substrate, the glass frit is softened and acts as a sintering aid. A suitable metal film can be adhered to the substrate. The bismuth-based glass frit has only to have a softening point that is lower than the heat resistance temperature (softening point) of the substrate, and the softening point can be selected within a range of about 500 ° C. or less, for example, 350 to 500 ° C., preferably 400 It may be about -490 ° C, preferably about 420-480 ° C (especially 450-470 ° C).

The bismuth-based glass frit only needs to contain bismuth oxide (Bi ₂ O ₃ ), and may contain other oxides in addition to bismuth oxide. Examples of other oxides include other metal oxides (for example, alkali metal oxides such as lithium oxide, sodium oxide, and potassium oxide; alkaline earth metal oxides such as magnesium oxide, calcium oxide, strontium oxide, and barium oxide). Periodic table group 4A metal oxides such as titanium oxide and zirconium oxide; periodic table group 6A metal oxides such as chromium oxide; periodic table group 8 metal oxides such as iron oxide; periodic table group 2B metals such as zinc oxide Oxides; periodic table group 3B metal oxides such as aluminum oxide; periodic table group 4B metal oxides such as tin oxide and lead oxide), silicon oxide, boron oxide and the like. These other oxides can be used alone or in combination of two or more. Of these oxides, they often contain barium oxide, zinc oxide, lead oxide, silicon oxide, boron oxide and the like. The ratio of bismuth oxide is, for example, 10% by mass or more, preferably 15% by mass or more (for example, 15 to 95% by mass), more preferably 20 to 90% by mass (particularly 30 to 80% by mass) with respect to the entire glass frit. %) Degree.

  The number average particle size (number average primary particle size) of the bismuth-based glass frit is, for example, 0.1 to 10 μm, preferably 0.2 to 8 μm, more preferably 0.3 to 5 μm (particularly 0.5 to 3 μm). It may be a degree. If the particle diameter of the bismuth glass frit is too large, clogging is likely to occur in screen printing, for example. On the other hand, if the particle size is too small, the dispersibility of the glass frit is lowered, so that the amount of glass frit used is increased and the conductivity is lowered.

  The ratio of the bismuth-based glass frit can be selected from a range of, for example, about 1 to 100 parts by weight, for example, 3 to 80 parts by weight, preferably 5 to 60 parts by weight, more preferably 100 parts by weight of the metal particles It is about 10-50 mass parts (especially 10-30 mass parts). If the proportion of the bismuth-based glass frit is too large, the conductivity is lowered, and if it is too small, the adhesion of the metal film to the substrate is lowered.

(Other additives)
The adhesive layer may further contain a dispersion medium and / or a binder resin.

The dispersion medium is not particularly limited as long as it is a solvent that generates sufficient viscosity in the paste by combining the metal particles and the bismuth-based glass frit, and a general-purpose solvent can be used, but in order to prepare a homogeneous paste It is preferable to use a solvent having an affinity for the dispersant, and may be an aromatic hydrocarbon such as toluene or xylene. For example, when the dispersant is hydrophilic, at least polar It is preferable to use a solvent having a group (particularly a non-aromatic solvent). Such solvents include aliphatic alcohols (e.g., saturated or unsaturated _C6-30 aliphatic alcohols such as ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, 2-ethyl-1-hexanol, octanol, decanol, etc.) ), Cellosolves (C _1-4 alkyl cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve), cellosolve acetates (C _1-4 alkyl cellosolve acetates such as ethyl cellosolve acetate), carbitols (methylcarbitol) C _1-4 alkyl carbitols such as ethyl carbitol, propyl carbitol and butyl carbitol), aliphatic polyhydric alcohols (for example, ethylene glycol, diethylene glycol, propylene, etc.) Lenglycol, dipropylene glycol, 1,4-butanediol, glycerin, etc.), alicyclic alcohols [eg, cycloalkanols such as cyclohexanol; terpene alcohols such as terpineol, dihydroterpineol (eg, monoterpene alcohol, etc.) ) Etc.] are widely used.

Of these dispersion media, saturated or unsaturated C _6-20 aliphatic alcohols such as octanol, aliphatic polyhydric alcohols such as ethylene glycol, and alicyclic alcohols such as terpineol are particularly preferable.

  The proportion of the dispersion medium may be, for example, 100 parts by mass or less with respect to 100 parts by weight of the metal particles, for example, 0.1 to 50 parts by mass, preferably 1 to 30 parts by mass, and more preferably 5 to 5 parts by mass. About 20 parts by mass.

  Binder resins include conventional binder resins such as water-soluble polymer binders (for example, water-soluble acrylic resins, water-soluble urethane resins, water-soluble acrylic urethane resins, water-soluble epoxy resins, water-soluble polyester resins, celluloses). Derivatives, polyvinyl alcohol, polyalkylene glycol, natural polymer, polyethylene sulfonic acid or its salt, polystyrene sulfonic acid or its salt, formalin condensate of naphthalene sulfonic acid, polyalkyleneimine, polyvinyl pyrrolidone, polyallylamine, polyether polyamine, etc.) , Hot melt resins (for example, polyester resins such as aliphatic or amorphous polyester, polyvinyl acetal resins such as polyvinyl butyral), thermosetting resins (for example, phenol resins, epoxy resins, etc.) Shi resins, such as unsaturated polyester resin) and the like.

  Among these binder resins, water-soluble polymer binders such as cellulose derivatives, such as cellulose ether (for example, nitrocellulose; alkyl cellulose such as ethyl cellulose, ethyl hydroxyethyl cellulose, etc.) from the point of acting as a polymer dispersant. Alkyl-hydroxyalkyl cellulose, hydroxyethyl cellulose, hydroxyalkyl cellulose such as hydroxypropyl cellulose, carboxyalkyl cellulose such as carboxymethyl cellulose, and the like, and alkyl cellulose such as ethyl cellulose is particularly preferable.

  The proportion of the binder resin may be, for example, 200 parts by mass or less, for example, 1 to 150 parts by mass, preferably 10 to 100 parts by mass, and more preferably 20 to 80 parts by mass with respect to 100 parts by mass of the metal particles. Part (particularly 30 to 60 parts by mass).

  The conductive paste for forming the adhesive layer includes conventional additives such as glass frits other than bismuth-based glass frit, colorants (dye pigments, etc.), hue improvers, dye fixing agents, depending on applications. Gloss imparting agent, metal corrosion inhibitor, stabilizer (antioxidant, UV absorber, etc.), surfactant or dispersant (anionic surfactant, cationic surfactant, nonionic surfactant, amphoteric surfactant) Agents), dispersion stabilizers, thickeners or viscosity modifiers, moisturizers, thixotropic agents, leveling agents, antifoaming agents, bactericides, fillers, and the like. These additives can be used alone or in combination of two or more.

  The first conductive paste for forming the adhesive layer is not particularly limited as long as the paste having the above configuration can be obtained. Usually, the metal particles and the bismuth-based glass frit are used as the dispersion medium and / or the binder resin. It can be prepared by dispersing in.

[Coating layer]
The coating layer contains metal nanoparticles and does not substantially contain a bismuth-based glass frit having a softening point of 500 ° C. or less, and usually bonds the conductive paste (second conductive paste) containing metal nanoparticles. It is formed by coating on the layer. In the present invention, the surface of the adhesive layer containing the bismuth glass frit by the coating layer substantially free of the bismuth glass frit having a low softening point (particularly, not including the bismuth glass frit having a low softening point). Therefore, the bismuth contained in the adhesive layer can be formed without acting as a catalyst poison for Ni plating (particularly Ni / Au plating).

  As a metal nanoparticle, the metal illustrated by the term of the metal particle of the said contact bonding layer can be used, and a silver nanoparticle is preferable. The particle size of the metal nanoparticles can also be selected from the same range as the number average particle size of the metal nanoparticles in the adhesive layer. Further, like the metal nanoparticles of the adhesive layer, they are usually used in combination with a dispersant. In particular, the surface of the metal nanoparticles may be coated with the dispersant. The proportion of the dispersant is also the same as that of the metal nanoparticles of the adhesive layer.

  Also in the coating layer, the metal nanoparticles may be combined with a metal filler in order to improve the conductivity of the sintered film. As the metal filler, the metal exemplified in the section of the metal particles of the adhesive layer can be used, and a silver filler is preferable. The particle size of the metal filler is also selected from the same range as the number average particle size of the metal filler of the adhesive layer and the same range as the ratio of the number average particle size of the metal nanoparticles and metal filler in the metal filler of the adhesive layer. it can.

  In the coating layer, a dense layer with few voids is formed by the sintered body, and the ratio of the metal nanoparticles to the metal nanoparticles and the metal filler is from the point of preventing the plating solution from permeating into the adhesive layer during the plating process. It is preferable that it is 30 mass% or more with respect to the total amount. If the proportion of the metal filler is too large, a large number of voids are generated in the coating layer, and the plating solution penetrates into the adhesive layer through the voids, erodes the adhesive layer, and the adhesive layer and the coating layer easily fall off. . That is, the ratio (mass ratio) between the metal nanoparticles and the metal filler can be selected from the range of metal nanoparticles / metal filler = about 30/70 to 100/0, and the metal nanoparticle can be prevented from penetrating. It is preferable that the proportion of particles is large, for example, 50/50 to 100/0, preferably 80/20 to 100/0, more preferably 90/10 to 100/0, and particularly only metal nanoparticles. May be. In addition, for example, metal nanoparticles / metal filler = 30/70 to 99/1, preferably 35/65 to 90/10, more preferably, from the viewpoint that both handleability of the paste and suppression of permeation of the plating solution can be achieved. It may be about 40/60 to 80/20.

The coating layer may also contain other additives exemplified in the section of the adhesive layer. Among the other additives, a dispersion medium (in particular, a saturated or unsaturated C _6-20 aliphatic alcohol such as octanol, an aliphatic polyhydric alcohol such as ethylene glycol, an alicyclic alcohol such as terpineol, etc.) is included. Is preferred. The ratio of the dispersion medium is, for example, 1 to 50 with respect to 100 parts by mass of metal particles (the total amount of metal nanoparticles and metal fillers when metal fillers are included, and metal nanoparticles when metal nanoparticles are used alone). The amount is about 3 to 30 parts by mass, preferably about 5 to 20 parts by mass (particularly 10 to 15 parts by mass).

  The second conductive paste for forming the coating layer is not particularly limited as long as the paste having the above-described configuration can be obtained. Usually, the metal nanoparticles (such as a metal filler if necessary) are used as the dispersion medium. It can be prepared by dispersing in.

[Laminate (conductive laminate precursor) and method for producing conductive laminate]
In the laminate of the present invention, an adhesive layer is formed on the substrate using the first conductive paste, and then a coating layer is formed on the adhesive layer using the second conductive paste. Can be manufactured.

  As a method for forming the adhesive layer, a method of coating the first conductive paste on the substrate can be used. Examples of the coating method include, for example, a flow coating method, a spin coating method, a spray coating method, a screen printing method, a flexographic printing method, a casting method, a bar coating method, a curtain coating method, a roll coating method, a gravure coating method, and a dipping method. , Slit method, photolithography method, ink jet method and the like. The adhesive layer may be formed on the entire surface, but is usually formed on a part of the surface of the substrate in a pattern or the like. When a pattern is formed (drawn) with a coating film, a sintered pattern (sintered film, metal film, sintered body layer, conductor layer) can be formed by firing the formed pattern (drawn pattern). The drawing method (or printing method) for drawing the pattern (coating layer) is not particularly limited as long as it is a pattern forming printing method. For example, a screen printing method, an ink jet printing method, an intaglio printing method (for example, Gravure printing method), offset printing method, intaglio offset printing method, flexographic printing method and the like. Of these methods, the screen printing method and the like are preferable.

  After coating, it may be naturally dried, but may be dried by heating. A heating temperature can be selected according to the kind of solvent, for example, is 100-300 degreeC, Preferably it is 150-280 degreeC, More preferably, it is about 200-250 degreeC. The heating time is, for example, about 1 minute to 3 hours, preferably about 5 minutes to 2 hours, and more preferably about 10 minutes to 1 hour.

  The average thickness of the adhesive layer is, for example, about 1 to 50 μm, preferably 3 to 30 μm, and more preferably about 5 to 15 μm.

  As a method for forming the coating layer, a method of coating the second conductive paste on the adhesive layer can be used. As a coating method, the same method as that for the adhesive layer can be used.

  The average thickness of the coating layer is, for example, about 3 to 75 μm, preferably about 10 to 50 μm, and more preferably about 15 to 30 μm.

  The average thickness ratio between the adhesive layer and the covering layer is, for example, adhesive layer / covering layer = 50/50 to 5/95, preferably 45/55 to 10/90, and more preferably about 40/60 to 15/85. is there.

  The obtained laminate is a precursor of the conductive laminate, and is subjected to a firing step in which the coating film is heated (or baked or heat-treated) at a predetermined temperature, whereby the substrate is interposed through the conductive adhesive layer. A conductive laminate having a conductive coating layer formed thereon is obtained. In addition, you may perform a drying process as needed prior to heat processing.

  In the firing step, the firing temperature is equal to or higher than the softening point of the bismuth-based glass frit (for example, 5 to 100 ° C., preferably 10 to 80 ° C., more preferably about 30 to 60 ° C. higher than the softening point), and The temperature is lower than the heat resistance temperature of the substrate. The firing temperature may be, for example, 400 to 520 ° C, preferably 450 to 510 ° C, more preferably about 480 to 500 ° C. The heat treatment time (heating time) may be, for example, 1 minute to 3 hours, preferably 5 minutes to 1 hour, more preferably about 10 to 30 minutes, depending on the heat treatment temperature and the like.

  The average thickness of the obtained conductive adhesive layer and conductive coating layer (fired film or metal film after sintering, sintered pattern) can be appropriately selected from the range of about 0.01 to 10000 μm depending on the application. It may be about 0.01 to 100 μm, preferably 0.1 to 50 μm, more preferably about 0.3 to 30 μm (particularly 0.5 to 10 μm). The average thickness ratio between the conductive adhesive layer and the conductive coating layer is, for example, conductive adhesive layer / conductive coating layer = 50/50 to 1/99, preferably 40/60 to 10/90, and more preferably 30/70 to 20 / 80 or so.

  In the conductive laminate of the present invention, the conductive coating layer is a dense layer with few voids, so that the plating solution permeates the adhesive layer even when a plating process such as Ni plating (particularly Ni / Au plating) is performed. Can be suppressed. The degree of voids in the conductive coating layer is represented by the ratio of the void area per unit area (porosity), and the porosity of the conductive coating layer may be 5% or less (for example, 0.01 to 5%). For example, 2% or less (for example, 0.03 to 2%), preferably 1% or less (for example, 0.05 to 1%), more preferably 0.5% or less (for example, 0.1 to 0. 2). 5%).

  In the conductive laminate of the present invention, a plating layer may be further formed on the conductive coating layer. As a method for forming the plating layer, a conventional plating process can be used. The present invention is effective for electroless plating among conventional plating processes, and particularly effective for electroless Ni plating (particularly electroless Ni / Au plating).

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, measurement methods for each physical property and materials used in the examples are shown below.

[Porosity of conductive coating layer]
About the obtained electroconductive laminated body, the surface of the electroconductive coating layer was observed with the scanning electron microscope, and the area of the space | gap in an area | region of 40 micrometers x 40 micrometers or more was computed using Digital Micrograph 3.4 by Gatan.

[Adhesion strength of electrode pattern]
An Sn-coated Cu wire was soldered to the electrode pattern after firing with SnAgCu solder, and the adhesion strength of the 2 mm × 2 mm electrode pattern was measured.

[Materials used]
Silver powder (SPN20J): “SPN20J” manufactured by Mitsui Mining & Smelting Co., Ltd., average particle diameter D50: 1.82 μm, D90: 3.14 μm
Silver powder (EHD): “EHD” manufactured by Mitsui Mining & Smelting Co., Ltd., average particle diameter D50: 0.48 μm, D90: 0.78 μm
Silver nanoparticles: “AG-404055” manufactured by Niraco Co., Ltd., average particle size 70 nm
Bismuth glass frit: “G3-3888” manufactured by Okuno Pharmaceutical Co., Ltd., softening point 458 ° C.
Ethyl cellulose: Nihon Kasei Co., Ltd. sales “EC-200”
Alkaline glass substrate: “S1225” manufactured by Iwanami Glass.

Example 1
(Preparation of conductive paste for adhesive layer formation)
Silver powder (SPN20J) 48 g, silver powder (EHD) 19 g, silver nanoparticles 33 g, bismuth-based glass frit 15 g, and ethyl cellulose 51 g were kneaded in an automatic mortar to prepare a conductive paste for forming an adhesive layer.

(Preparation of conductive paste for coating layer formation)
45 g of silver powder (SPN20J), 46 g of silver nanoparticles (AG-404055) and 9 g of terpineol were kneaded in an automatic mortar to prepare a conductive paste for forming a coating layer.

(Conductive film printing and firing)
A conductive paste for forming an adhesive layer was screen-printed on an alkali glass substrate according to an electrode pattern of 2 mm × 2 mm. The glass substrate on which the pattern of the adhesive layer was printed was dried in a hot air circulating oven at 200 ° C. for 30 minutes. Thereafter, a conductive paste for forming a coating layer was screen-printed on the pattern of the adhesive layer. The average thickness of the adhesive layer was 5 μm, and the average thickness of the coating layer was 15 μm. In a muffle furnace, the temperature was raised from room temperature to 500 ° C. at a rate of 10 ° C./min, and the temperature was maintained at 500 ° C. for 10 minutes, and the adhesive layer and the coating layer were simultaneously fired. Thereafter, it was gradually cooled to room temperature. A relatively small number of voids having a size of less than 3 μm were observed on the surface of the conductive coating layer of the obtained conductive laminate.

(Adhesion strength)
The Sn-coated Cu wire was soldered to the electrode pattern after firing with SnAgCu solder, and the adhesion strength of the 2 mm × 2 mm electrode pattern was measured. As a result, a strength of 1.4 kgf was obtained.

(Plating treatment)
When electroless Ni / Au plating was performed, it was confirmed that Ni / Au plating was deposited on all the patterns without dropping off the patterns.

(Adhesion strength after Ni / Au plating)
As a result of soldering an Sn-coated Cu wire with SnAgCu solder to the electrode pattern after the Ni / Au plating treatment and measuring the adhesion strength of the 2 mm × 2 mm electrode pattern, a strength of 1.3 kgf was obtained. Never fell.

(Adhesion strength reliability test)
A sample in which an Sn-coated Cu wire was soldered to the electrode pattern after the Ni / Au plating treatment with SnAgCu solder was left for 1000 hours at 125 ° C., relative humidity 85%, and pressure 1.6 atm. When the adhesion strength of the electrode was measured after 1000 hours, the strength of 1.3 kgf was maintained, and it was confirmed that there was long-term reliability.

Example 2
A conductive laminate was prepared in the same manner as in Example 1 except that the coating layer forming conductive paste was prepared by the following method.

(Preparation of conductive paste for coating layer formation)
Silver powder (SPN20J) 48 g, silver powder (EHD) 19 g, silver nanoparticles 33 g, and terpineol 12 g were kneaded in an automatic mortar to prepare a conductive paste for forming a coating layer. The average thickness of the coating layer was 20 μm.

  A relatively small number of voids having a size of less than 3 μm were observed on the surface of the conductive coating layer of the obtained conductive laminate. The porosity of the conductive coating layer was 1.95%. When electroless Ni / Au plating was performed, it was confirmed that Ni / Au plating was deposited on all the patterns without dropping off the patterns.

Example 3
A conductive laminate was prepared in the same manner as in Example 1 except that the coating layer forming conductive paste was prepared by the following method.

(Preparation of conductive paste for coating layer formation)
90 g of silver nanoparticles and 12 g of terpineol were kneaded in an automatic mortar to prepare a conductive paste for forming a coating layer. The average thickness of the coating layer was 15 μm.

  A small number of voids having a size of less than 3 μm were observed on the surface of the conductive coating layer of the obtained conductive laminate. The porosity of the conductive coating layer was 0.18%. When electroless Ni / Au plating was performed, it was confirmed that Ni / Au plating was deposited on all the patterns without dropping off the patterns.

Comparative Example 1
A conductive laminate was produced in the same manner as in Example 1, except that the coating layer forming conductive paste was not overcoated on the adhesive layer pattern. The obtained laminate was not subjected to plating by the electroless Ni / Au plating treatment, and pattern dropping was observed.

Comparative Example 2
A conductive laminate was prepared in the same manner as in Example 1 except that the conductive paste for forming a coating layer was prepared by the following method (without silver nanoparticles).

(Preparation of conductive paste for coating layer formation)
60 g of silver powder (SPN20J), 40 g of silver powder (EHD), and 10 g of ethyl cellulose were kneaded in an automatic mortar to prepare a conductive paste for forming a coating layer.

  Numerous voids including voids having a size exceeding 3 μm were observed on the surface of the conductive coating layer of the obtained conductive laminate. The porosity of the conductive coating layer was 7.39%. By the electroless Ni / Au plating treatment, no plating was deposited, and pattern loss was observed.

  The conductive laminate of the present invention includes, for example, electrodes such as a plasma display panel (PDP), a fluorescent display tube (VFD), a liquid crystal display (LCD), an organic electroluminescence display (ELD), and a touch panel display device. It can be used as a conductive film used in an RFID tag, an electromagnetic wave shield, a home or learning wiring kit, and the like.

Claims (18)

  A laminate in which a coating layer is formed on a substrate via an adhesive layer, wherein the adhesive layer includes metal particles and a bismuth-based glass frit having a softening point of 500 ° C. or less, and the coating layer includes: A laminate containing metal nanoparticles and substantially free of bismuth-based glass frit having a softening point of 500 ° C. or lower.   The laminate according to claim 1, wherein the metal nanoparticles have a number average particle diameter of 10 to 100 nm.   The laminate according to claim 1 or 2, wherein the metal nanoparticles are conductive metal particles.   The laminate according to any one of claims 1 to 3, wherein the metal nanoparticles are silver nanoparticles.   The laminate according to any one of claims 1 to 4, wherein the surface of the metal nanoparticles is coated with a dispersant.   The coating layer further includes a metal filler having a number average particle size of 200 nm or more, and the ratio (mass ratio) of the metal nanoparticles to the metal filler is metal nanoparticles / metal filler = 30/70 to 99/1, And the ratio of a number average particle diameter is metal nanoparticle / metal filler = 1 / 1000-1 / 5, The laminated body in any one of Claims 1-5.   The laminate according to any one of claims 1 to 6, wherein the coating layer further contains a dispersion medium and / or a binder resin.   The laminated body in any one of Claims 1-7 in which an contact bonding layer contains 10-50 mass parts of bismuth-type glass frit with respect to 100 mass parts of metal particles.   The laminate according to any one of claims 1 to 8, wherein the adhesive layer further contains a dispersion medium and / or a binder resin, and the metal particles contain silver nanoparticles and a silver filler.   The laminate according to any one of claims 1 to 9, wherein an average thickness ratio between the adhesive layer and the coating layer is adhesive layer / covering layer = 50/50 to 5/95.   The laminate according to any one of claims 1 to 10, wherein the substrate is a glass substrate.   The laminate according to any one of claims 1 to 11 is baked at a temperature not lower than a softening point of a bismuth-based glass frit and not higher than a heat resistant temperature of the substrate, and conductively coated on the substrate via a conductive adhesive layer. A method for producing a conductive laminate having a layer formed thereon.   The method according to claim 12, further comprising forming a plating layer on the conductive coating layer.   The method according to claim 13, wherein the plating layer is a Ni / Au plating layer.   The electroconductive laminated body obtained by the method in any one of Claims 12-14.   The conductive laminate according to claim 15, wherein the porosity of the conductive coating layer is 2% or less.   The conductive laminate according to claim 14 or 15, wherein a Ni / Au plating layer is formed on the conductive coating layer.   A laminate in which a conductive coating layer formed of silver is formed on a substrate via a conductive adhesive layer formed of silver and a bismuth-based glass frit having a softening point of 500 ° C. or less, wherein the conductive coating layer A conductive laminate having a porosity of 5% or less.