JP6871574B2 - Metal plating method - Google Patents

Description

The present invention relates to metal plating methods and resistors.

As a technique for forming a metal plating layer on the surface of a ceramic base material, a method of adsorbing a metal ion as a catalyst on the surface of the base material and depositing a metal on the metal ion by an electroless plating method is common (for example, a patent). Reference 1). Further, after the surface of the ceramic base material is etched to make an uneven rough surface, a plating layer is formed on the uneven rough surface, so that the adhesion between the ceramic base material and the metal plating layer can be improved by the anchor effect. It is known that it can be done.
On the other hand, a technique is known in which gold fine particles are fixed to the surface of a plastic base material via a binder having a thiol group to perform primary plating, and secondary plating is performed by electroless plating (see, for example, Patent Document 2). ).

Japanese Unexamined Patent Publication No. 2001-206735 Japanese Unexamined Patent Publication No. 2013-170293

Since different phases of metal and ceramic are mixed on the surface of the composite base material made of metal and ceramic, it is difficult to form a metal plating layer having uniform adhesion strength by the conventional electroless plating method. Further, when the temperature of the composite material is changed, the metal plating layer may be peeled off from the composite material due to the difference in the coefficient of thermal expansion. In particular, when an electric current is passed through a resistor made of metal and ceramics, the resistor self-heats. When a metal plating layer is formed as a terminal on the surface of such a resistor, the metal plating layer may be peeled off due to a temperature change of the resistor.
The present invention has been made in view of such circumstances, and provides a metal plating method capable of forming a metal plating layer having high adhesion strength on a base material having a ceramic surface and a metal surface.

The present invention provides a primary plating step of forming a primary plating layer composed of a plurality of metal nanoparticles on the substrate by fixing the plurality of metal nanoparticles to the surface of the substrate using at least one kind of binder. The base material comprises a ceramic surface and a metal surface, and at least one kind of binder fixes a part of a plurality of metal nanoparticles to the ceramic surface and attaches other metal nanoparticles to the metal. Provided is a metal plating method characterized by fixing to a surface.
Here, each of at least one type of binder may be bonded to only one of the ceramic surface and the metal surface, but at least one type of binder is in a state of straddling both the ceramic surface and the metal surface. May include a binder that immobilizes the metal nanoparticles in. Further, all of at least one kind of binder may be a binder for fixing the metal nanoparticles while straddling both the ceramic surface and the metal surface.

In the metal plating method of the present invention, a plurality of metal nanoparticles are fixed to the surface of a base material using at least one kind of binder to form a primary plating layer composed of the plurality of metal nanoparticles on the base material. Includes primary plating process. Further, the base material has a ceramic surface and a metal surface. Therefore, the primary plating layer can be formed on the base material having the ceramic surface and the metal surface.
At least one kind of binder used in the primary plating step fixes a part of a plurality of metal nanoparticles to the ceramic surface of the base material, and fixes other metal nanoparticles to the metal surface of the base material. That is, at least one type of binder does not fix a plurality of metal nanoparticles only on the ceramic surface or only on the metal surface, but some of the plurality of metal nanoparticles are fixed on the ceramic surface on the metal surface. Some are fixed. Therefore, it is possible to form a primary plating layer that uniformly covers the surface of the base material without roughening the surface of the base material, and the plurality of metal nanoparticles constituting the primary plating layer are the base material. High adhesion strength can be uniformly obtained with respect to the surface of the plating.
Further, this primary plating layer can be used as a core for precipitating the secondary plating layer, and it becomes possible to form a metal plating layer having a sufficient thickness on the base material. Therefore, it is possible to form a metal plating layer having high adhesion strength on a base material having a ceramic surface and a metal surface. This has been demonstrated by experiments conducted by the present inventors.
Further, the metal plating layer formed by using the metal plating method of the present invention has excellent heat resistance and can suppress peeling from the base material even when the base material becomes high temperature. This has been demonstrated by experiments conducted by the present inventors.

(A) and (b) are schematic cross-sectional views of the metal-plated product of one embodiment of the present invention, respectively. (A) and (b) are schematic cross-sectional views of the metal-plated product of one embodiment of the present invention, respectively. (A) is a schematic perspective view of a resistor according to an embodiment of the present invention, and (b) is a schematic cross-sectional view of a resistor including a resistor according to an embodiment of the present invention. It is a flowchart of a primary plating process. It is a flowchart of a primary plating process. It is a flowchart of a primary plating process. It is a flowchart of a primary plating process. It is a flowchart of a primary plating process. It is a conceptual diagram of the metal nanoparticles fixed to the ceramic surface of a base material by a 1st binder. (A) is a conceptual diagram of metal nanoparticles fixed to the metal surface of the base material by the second binder, and (b) is a conceptual diagram of the metal nanoparticles fixed to the metal surface of the base material by the third binder. (C) is a conceptual diagram of metal nanoparticles fixed to the surface of ceramics of a base material by a third binder.

In the metal plating method of the present invention, a plurality of metal nanoparticles are fixed to the surface of a base material using at least one kind of binder to form a primary plating layer composed of the plurality of metal nanoparticles on the base material. Including a primary plating step, the substrate has a ceramic surface and a metal surface, and at least one kind of binder fixes a part of a plurality of metal nanoparticles to the ceramic surface and other metal nanos. It is characterized in that the particles are fixed to the metal surface.

In the primary plating step included in the metal plating method of the present invention, a first binder for fixing a part of a plurality of metal nanoparticles to the ceramic surface and a second binder for fixing other metal nanoparticles to the metal surface are provided. It is preferable that the step is to form a primary plating layer by using the metal. The first binder is preferably a silane coupling agent having a thiol group, a disulfide group, an amino group or a glycidyl group. The second binder is preferably an organic compound having a first functional group adsorbed on the metal nanoparticles and a second functional group adsorbed on the metal surface, and the first and second functional groups are thiol groups. , Disulfide group, amino group or glycidyl group is preferable. When a silane coupling agent having a thiol group, a disulfide group, an amino group or a glycidyl group is used as the first binder, the metal nanoparticles can be fixed to the ceramic surface of the base material. When an organic compound in which the first and second functional groups are a thiol group, a disulfide group, an amino group or a glycidyl group is used as the second binder, the metal nanoparticles can be fixed to the metal surface of the base material. Therefore, a primary plating layer that uniformly covers the surface of the base material can be formed.

The primary plating step included in the metal plating method of the present invention is preferably a step of forming a primary plating layer using a third binder that fixes a plurality of metal nanoparticles on the ceramic surface and the metal surface. The third binder is preferably a silane coupling agent having a third functional group adsorbed on the metal nanoparticles and a fourth functional group adsorbed on the metal surface, and the third and fourth functional groups are It is preferably a thiol group, a disulfide group, an amino group or a glycidyl group. When a silane coupling agent in which the third and fourth functional groups are a thiol group, a disulfide group or an amino group is used as the third binder, the metal nanoparticles can be fixed to the ceramic surface and the metal surface of the base material. Therefore, a primary plating layer that uniformly covers the surface of the base material can be formed.
Although only the third binder may be used as at least one type of binder, the first binder, the second binder, and the third binder may be used in combination.

The base material is preferably a composite sintered body having a ceramic phase and a metal phase, the ceramic surface is preferably the ceramic phase, and the metal surface is preferably the metal phase. .. In this case, the first plating layer can be formed on the surface of the composite sintered body by the metal plating method of the present invention.
The ceramic phase is preferably an inorganic oxide phase, and Li, Be, B, N, F, Na, Mg, Al, Si, P, K, Ca, Ti, Cu, Zn, Y, Zr, Nb. , Ba, preferably containing oxides of one or more elements. In this case, the ceramic surface of the base material can have a hydroxyl group, and this hydroxyl group can undergo a condensation reaction with the silanol group of the silane coupling agent.

The metal plating method of the present invention preferably further includes a secondary plating step of forming a secondary plating layer by electroplating or electroless plating a base material on which a primary plating layer is formed. By performing the secondary plating step, the thickness of the metal plating layer covering the base material can be increased, and the conductivity of the metal plating layer can be improved.
The metal plating method of the present invention preferably further includes a tertiary plating step of forming a tertiary plating layer by electroplating or electroless plating a substrate on which a secondary plating layer is formed. By performing the tertiary plating step, it is possible to produce a metal-plated product in which the base material is covered with a multi-layered metal plating layer.

The present invention has a base material having a ceramic surface and a metal surface, and a metal plating layer provided on the ceramic surface and the metal surface, and a thiol is formed at the interface between the base material and the metal plating layer. Also provided is a metal-plated product characterized by having a compound having a group, or a decomposition product or reaction product thereof. The metal-plated product of the present invention has a metal-plated layer having high adhesion strength and excellent heat resistance. This has been demonstrated by experiments conducted by the present inventors.
The present invention has a composite sintered body having a ceramics phase and a metal phase, and a metal plating layer provided on the ceramics phase and the metal phase, and the metal plating layer is electrically formed with the metal phase. A resistor terminal for which the composite sintered body and the metal plating layer are connected to each other, and also having a compound having a thiol group, or a decomposition product or reaction product thereof at the interface between the composite sintered body and the metal plating layer. provide. The resistor of the present invention has a resistor terminal (metal plating layer) having high adhesion strength and excellent heat resistance. This has been demonstrated by experiments conducted by the present inventors.

Hereinafter, the present invention will be described in more detail with reference to a plurality of embodiments. The configurations shown in the drawings and the following description are examples, and the scope of the present invention is not limited to those shown in the drawings and the following description.

1 (a) and 1 (b) are schematic cross-sectional views of a metal-plated product in which a primary plating layer is formed on a base material by the metal plating method of the present embodiment, respectively. FIG. 2A is a schematic cross-sectional view of a plated product in which a primary plating layer and a secondary plating layer are formed on a base material by the metal plating method of the present embodiment, and FIG. 2B is a schematic cross-sectional view of the present embodiment. It is a schematic cross-sectional view of a plated product in which a primary plating layer, a secondary plating layer and a tertiary plating layer are formed on a base material by a metal plating method. FIG. 3A is a schematic perspective view of the resistor of the present embodiment, and FIG. 3B is a schematic cross-sectional view of the resistor including the resistor of the present embodiment.
In the metal plating method of the present embodiment, a plurality of metal nanoparticles 1 are fixed to the surface of the base material 5 by using at least one kind of binder 2, so that a primary composed of the plurality of metal nanoparticles 1 is formed on the base material 5. Including a primary plating step of forming a plating layer 4, the base material 5 has a ceramic surface 7 and a metal surface 9, and at least one kind of binder 2 has a part of a plurality of metal nanoparticles 1 on the ceramic surface 7. It is characterized in that it is fixed to the metal surface 9 and the other metal nanoparticles 1 are fixed to the metal surface 9. By the metal plating method of the present embodiment, the metal-plated product 13 or the resistor 15 of the present embodiment can be manufactured. Further, the metal plating method of the present embodiment can include a secondary plating step. Further, the metal plating method of the present embodiment can include a tertiary plating step.

The metal-plated product 13 of the present embodiment has a base material 5 having a ceramic surface 7 and a metal surface 9, and a metal plating layer 18 provided on the ceramic surface 7 and the metal surface 9, and the base material 5 It is characterized by having a compound having a thiol group, or a decomposition product or reaction product thereof, at the interface with the metal plating layer 18.
The resistor 15 of the present embodiment has a composite sintered body 28 having a ceramic phase 6 and a metal phase 8, and a metal plating layer 18 provided on the ceramic phase 6 and the metal phase 8, and is metal-plated. The layer 18 is a resistor terminal 20 that is electrically connected to the metal phase 8, and is a compound having a thiol group at the interface between the composite sintered body 28 and the metal plating layer 18, or a decomposition product or reaction product thereof. It is characterized by having.
Hereinafter, the metal plating method, the metal-plated product 13, and the resistor 15 of the present embodiment will be described.

1. 1. Base material The base material 5 used in the metal plating method of the present embodiment is an object to be plated, and a metal plating layer 18 is formed on the base material 5. The base material 5 has a ceramic surface 7 and a metal surface 9. The ceramic surface 7 is the surface of the ceramic phase 6 of the surface of the base material 5, and the metal surface 9 is the surface of the metal phase 8 of the surface of the base material 5. The ceramic surface 7 may be an inorganic oxide surface. The surface of the base material having the ceramic surface 7 and the metal surface 9 serves as a base for the primary plating step.
For example, the base material 5 is a composite material of ceramics and metal. Further, the base material 5 may be a composite sintered body 28 having a ceramic phase 6 and a metal phase 8.

Here, the case where the base material 5 is the composite sintered body 28 will be described.
The composite sintered body 28 is obtained by mixing and sintering ceramic powders and metal powders. The powder or granular material includes those having a particle size of several nm to those having a particle size of several hundred μm. Further, the composite sintered body 28 may be sintered at a temperature at which the ceramic powder or granular material is softened or melted or higher and the metal powder or granular material is not melted. For example, the composite sintered body 28 may be one obtained by sintering at a temperature of 600 ° C. or higher and 1500 ° C. or lower. Further, the mixing ratio (volume ratio) of the powder or granular material can be, for example, 80:20 to 40:60 for ceramics: metal. That is, when the total of ceramics and metal is 100%, ceramics can be 40% to 80% and metal can be 20% to 60%.
The ceramic powder or granular material becomes the ceramic phase 6 of the composite sintered body 28 by sintering, and the metal powder or granular material becomes the metal phase 8 of the composite sintered body 28 by sintering. Further, the portion of the surface of the composite sintered body 28 that is the ceramic phase 6 is the ceramic surface 7, and the portion of the surface of the composite sintered body 28 that is the metal phase 8 is the metal surface 9.
The composite sintered body 28 may have a ceramic phase 6 as a matrix. Further, the composite sintered body 28 can have a structure in which the particulate metal phase 8 is dispersed and contacted in the ceramic phase 6 which is a matrix. This makes it possible to manufacture the resistor 15 having a relatively high electric resistance value by using the composite sintered body 28.

The ceramic phase 6 contained in the composite sintered body 28 is an inorganic oxide phase, and Li, Be, B, N, F, Na, Mg, Al, Si, P, K, Ca, Ti, Cu, Zn, It contains oxides of one or more elements of Y, Zr, Nb and Ba. The ceramic powder or granular material used as the raw material for the ceramic phase 6 is, for example, a glass powder or granular material. The glass powder or granular material may be one that melts or softens at the time of sintering. Further, the ceramic powder or granular material may be an alumina powder or granular material, a zirconia powder or granular material, a magnesia powder or granular material, a mullite powder or granular material or the like. Further, the ceramic powder or granular material may be crushed ceramics, roof tiles, insulators, or the like. The ceramic powder or granular material used as the raw material of the ceramic phase 6 may be a mixture of a plurality of the exemplified powder or granular material.
The average particle size of the ceramic powder or granular material before sintering can be, for example, 50 μm or less.

The metal phase 8 contained in the composite sintered body 28 may contain, for example, nichrome. Nichrome may be, for example, an alloy containing 55 to 90% Ni, 10 to 25% Cr, and 0 to 26% Fe. Further, the metal phase 8 contained in the composite sintered body 28 may include stainless steel.
The metal powder or granular material used as the raw material of the metal phase 8 may be, for example, a nichrome powder or granular material, a stainless steel powder or granular material, or a mixed powder or granular material of nichrome and stainless steel. Good. The average particle size of the metal powder or granular material before sintering is, for example, 1 μm or more and 200 μm or less. The shape of the metal powder or granular material before sintering is, for example, spherical, plate-shaped, flat-shaped, or the like.

2. Primary plating step In the primary plating step, a plurality of metal nanoparticles 1 are fixed to the surface of the base material 5 using at least one kind of binder 2, so that the primary plating composed of the plurality of metal nanoparticles 1 is formed on the base material 5. This is a step of forming the layer 4. The primary plating step is a step of forming the primary plating layer 4 by the electroless plating method. The electroless plating method is a method of plating without passing an electric current.
The primary plating step can be performed, for example, by a procedure as shown in the flowcharts shown in FIGS. 4 to 8. Although the primary plating step includes the preparation of the metal nanoparticle dispersion liquid in FIGS. 4 to 8, the prepared metal nanoparticle dispersion liquid may be used in the primary plating step. Further, in FIGS. 4 to 8, the primary plating step includes a heat treatment, but the heat treatment may be omitted. When the metal plating layer 18 is formed on a part of the surface of the base material 5, a part of the surface of the base material 5 can be covered with a mask before the primary plating step.

The metal nanoparticle dispersion liquid can be prepared, for example, by adding a reducing agent to an aqueous solution in which a metal compound is dissolved and stirring the aqueous solution at room temperature to 95 ° C. for 5 minutes to 24 hours. As a result, the metal ions in the aqueous solution can be reduced by the reducing agent, and the metal nanoparticles 1 can be generated in the aqueous solution. The average particle size of the metal nanoparticles 1 is, for example, 1 nm or more and 50 nm or less.
The metal nanoparticle dispersion liquid is, for example, a gold nanoparticle dispersion liquid, a silver nanoparticle dispersion liquid, a palladium nanoparticle dispersion liquid, or the like. The gold nanoparticle dispersion liquid can be prepared, for example, by adding a reducing agent to an aqueous solution of tetrachloroauric acid. The silver nanoparticle dispersion liquid can be prepared, for example, by adding a reducing agent to an aqueous silver nitrate solution. The palladium nanoparticle dispersion liquid can be prepared, for example, by adding a reducing agent to an aqueous solution of palladium nitrate.

The reducing agent is not limited as long as it can reduce metal ions, and is, for example, sodium borohydride, hydrogen peroxide, and the like.
The metal nanoparticle dispersion liquid may or may not contain a dispersant. The metal nanoparticle dispersion liquid can contain, for example, citric acid, sodium citrate, alcohol, polyethylene glycol, polyvinylpyrrolidone and the like as a dispersant. Further, the metal nanoparticle dispersion liquid may contain a pH adjuster.

In the primary plating step, the primary plating layer uses a first binder 2a for fixing a part of the plurality of metal nanoparticles 1 to the ceramic surface 7 and a second binder 2b for fixing the other metal nanoparticles 1 to the metal surface 9. It may be a step of forming 4. In this case, the primary plated product 13 as shown in FIG. 1A can be manufactured by the primary plating step. Note that FIG. 1 shows only the metal nanoparticles 1 fixed to the surface of the base material 5 by the binder 2 as the metal nanoparticles 1 constituting the primary plating layer 4, but the primary plating layer 4 is the base material. It also includes the metal nanoparticles 1 attached to the metal nanoparticles 1 fixed to the surface of 5.
The first binder 2a is an organic compound having a functional group adsorbed on the ceramic surface 7 of the base material 5 and a functional group adsorbed on the metal nanoparticles 1. The adsorption includes physical adsorption and chemical adsorption. In FIG. 1A, the functional groups adsorbed on the ceramic surface 7 are indicated by black circles, and the functional groups adsorbed on the metal nanoparticles 1 are indicated by white circles.

Examples of the functional group adsorbed on the surface 7 of the ceramics include a silanol group (-SiOH), a hydrolyzable group bonded to a silicon atom (for example, -Si-OCH ₃ , -Si-OC ₂ H ₅ , -Si-OCOCH _{3 and the} like. ) And so on. In this case, the first binder 2a serves as a silane coupling agent. _{The silane coupling agent is an organosilicon compound (Y—Si—OR n} ) having both an organic functional group “Y” and a hydrolyzable group “OR”. When the silane coupling agent is adsorbed on the ceramic surface 7 of the base material 5, for example, water is added to the silane coupling agent to promote the hydrolysis reaction of the hydrolyzable group, and the hydrolyzable group is a silanol group (-Si). Convert to −OH). By advancing the dehydration condensation reaction between the silanol group and the hydroxyl group (−OH) of the ceramic surface 7, the first binder 2a can be chemically adsorbed on the ceramic surface 7.

Examples of the functional group adsorbed on the metal nanoparticles 1 include a thiol group (-SH), a disulfide group (-SS-), an amino group (-NH ₂ ), and a glycidyl group. Since the sulfur atom has a high affinity with the metal atom, the thiol group or the disulfide group is adsorbed on the metal nanoparticles 1. Further, the amino group is adsorbed on the metal nanoparticles 1 by electrostatic interaction. When the first binder 2a is a silane coupling agent, the organic functional group "Y" of the silane coupling agent can have a thiol group, a disulfide group, an amino group or a glycidyl group. With this first binder 2a, the metal nanoparticles 1 can be fixed to the ceramic surface 7. Further, the bonding strength between the metal nanoparticles 1 and the ceramic surface 7 can be increased.
The first binder 2a is, for example, an amino-based silane coupling agent such as N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, or 3-mercaptopropylmethyldimethoxysilane. It is a mercapto-based silane coupling agent.

FIG. 9 is a conceptual diagram in the case where the metal nanoparticles 1 are fixed to the ceramic surface 7 of the base material 5 by using an amino silane coupling agent. First, water is added to the amino-based silane coupling agent to hydrolyze the hydrolyzable group, and the silane coupling agent is chemically adsorbed on the ceramic surface 7 by dehydration condensation reaction with the hydroxyl group of the ceramic surface 7 of the base material 5. .. Then, by adsorbing the amino group of the silane coupling agent on the metal nanoparticles 1, the metal nanoparticles 1 can be fixed to the ceramic surface 7 of the base material 5 via the silane coupling agent.

The second binder 2b is an organic compound having a functional group adsorbed on the metal surface 9 of the base material 5 and a functional group adsorbed on the metal nanoparticles 1. In FIG. 1A, the functional groups adsorbed on the metal surface 9 are indicated by black squares, and the functional groups adsorbed on the metal nanoparticles 1 are indicated by white circles.
Examples of the functional group adsorbed on the metal surface 9 include a thiol group (-SH), a disulfide group (-SS-), an amino group (-NH ₂ ), and a glycidyl group. Examples of the functional group adsorbed on the metal nanoparticles 1 include a thiol group (-SH), a disulfide group (-SS-), an amino group (-NH ₂ ), and a glycidyl group. The second binder 2b is an organic compound having a thiol group or a disulfide group as a functional group adsorbed on the metal surface 9 and an amino group (-NH _{2) as a functional group adsorbing on the metal nanoparticles 1.} May be good.
Therefore, when the second binder 2b has such a functional group, the metal nanoparticles 1 can be fixed to the metal surface 9. Further, the bonding strength between the metal nanoparticles 1 and the metal surface 9 can be increased.
The second binder 2b is, for example, 4-aminothiophenol, aminophenyl disulfide, or the like. The second binder 2b can fix the metal nanoparticles 1 to the metal surface 9 of the base material 5, for example, as shown in FIG. 10A.

In the primary plating step, for example, as shown in the flowchart shown in FIG. 4, the base material 5 is immersed in the metal nanoparticle dispersion liquid, the first binder 2a and the second binder 2b are added to the metal nanoparticle dispersion liquid, and then the base material 5 is added. The step may be a step of forming the primary plating layer 4 on the base material 5 by stirring or allowing the metal nanoparticle dispersion liquid to stand. The time for stirring or standing may be, for example, 1 hour or more and 48 hours or less.
In this case, the metal nanoparticles 1, the base material 5, the first binder 2a and the second binder 2b are present in the metal nanoparticle dispersion liquid. Therefore, the first binder 2a is adsorbed on the ceramic surface 7 and the metal nanoparticles 1 of the base material 5, and the metal nanoparticles 1 are fixed to the ceramic surface 7. Further, the second binder 2b is adsorbed on the metal surface 9 and the metal nanoparticles 1 of the base material 5 to fix the metal nanoparticles 1 on the ceramic surface 7. Therefore, the primary plating layer 4 that uniformly covers the surface of the base material 5 can be formed. Further, since the metal nanoparticles 1 constituting the primary plating layer 4 are fixed to the surface of the base material 5 by the first binder 2a and the second binder 2b, the adhesion strength of the primary plating layer 4 to the surface of the base material 5 is strong. Can be raised. Further, the primary plating layer 4 can be used as a core for precipitating the secondary plating layer 10, and a metal plating layer 18 having a sufficient thickness can be formed on the base material 5. ..

In the primary plating step, for example, as shown in the flowchart shown in FIG. 5, the first binder 2a is adsorbed on the ceramic surface 7 of the base material 5 by performing the surface treatment of the base material 5 using the first binder 2a. After that, the base material 5 is immersed in the metal nanoparticle dispersion liquid, the second binder 2b is added to the metal nanoparticle dispersion liquid, and the metal nanoparticle dispersion liquid is stirred or allowed to stand to perform primary plating on the base material 5. It may be a step of forming the layer 4. In this case, in the surface treatment, the first binder 2a is adsorbed on the ceramic surface 7 of the base material 5, and the second binder 2b is adsorbed on the metal surface 9 in the metal nanoparticle dispersion liquid. And the conditions for adsorbing the second binder 2b can be changed. For example, the pH and temperature at the time of adsorption can be changed. As a result, the primary plating layer 4 can be efficiently formed. Further, it is possible to prevent the extra first binder 2a from adhering to the metal nanoparticles 1 constituting the primary plating layer 4.

In the primary plating step, for example, as shown in the flowchart shown in FIG. 6, the surface treatment of the base material 5 is performed using the first binder 2a and the second binder 2b, so that the first binder is applied to the ceramic surface 7 of the base material 5. After adsorbing 2a and adsorbing the second binder 2b on the metal surface 9, the base material 5 is immersed in the metal nanoparticle dispersion liquid, and the metal nanoparticle dispersion liquid is stirred or allowed to stand on the base material 5. It may be a step of forming the primary plating layer 4. In this case, in the surface treatment, the first binder 2a is adsorbed on the ceramic surface 7 of the base material 5, the second binder 2b is adsorbed on the metal surface 9, and then the first and second binders 2 are formed in the metal nanoparticle dispersion liquid. Adsorbs metal nanoparticles 1. In this case, the conditions for adsorbing the first and second binders 2 on the base material 5 and the conditions for adsorbing the metal nanoparticles 1 on the first and second binders 2 do not have to be the same, and are suitable for each adsorption. It can be done by selecting the above conditions. As a result, the primary plating layer 4 can be efficiently formed.

The primary plating step may be a step of forming the primary plating layer 4 by using a third binder 2c for fixing a plurality of metal nanoparticles 1 on the ceramic surface 7 and the metal surface 9 of the base material 5. In this case, the primary plated product 13 as shown in FIG. 1B can be manufactured by the primary plating step.
The third binder 2c is an organic compound having a functional group adsorbed on the ceramic surface 7 of the base material 5, a functional group adhering to the metal surface 9 of the base material 5, and a functional group adhering to the metal nanoparticles 1. .. In FIG. 1B, the functional groups adsorbed on the ceramic surface 7 are indicated by black circles, the functional groups adsorbed on the metal surface 9 are indicated by black squares, and the functional groups adsorbed on the metal nanoparticles 1 are indicated by black squares. It is indicated by a white circle.

Examples of the functional group adsorbed on the surface 7 of the ceramics include a silanol group (-SiOH), a hydrolyzable group bonded to a silicon atom (for example, -Si-OCH ₃ , -Si-OC ₂ H ₅ , -Si-OCOCH _{3 and the} like. ) And so on. For example, the alkoxy group of the silane coupling agent chemically bonds (condenses) to the ceramic surface 7 and adsorbs it.
Examples of the functional group adsorbed on the metal surface 9 include a thiol group (-SH), a disulfide group (-SS-), an amino group (-NH ₂ ), and a glycidyl group. Examples of the functional group adsorbed on the metal nanoparticles 1 include a thiol group, a disulfide group, an amino group, and a glycidyl group.

When the third binder 2c is a silane coupling agent (Y—Si—OR _n ), the organic functional group “Y” of the silane coupling agent is adsorbed on the functional group adsorbed on the metal surface 9 and on the metal nanoparticles 1. It has a functional group. With this third binder 2c, the metal nanoparticles 1 can be fixed to the ceramic surface 7 and the metal surface 9. Further, the bonding strength between the metal nanoparticles 1 and the surface of the base material 5 can be increased.
The third binder 2c can fix the metal nanoparticles 1 to the metal surface 9 of the base material 5 as shown in FIG. 10 (b), and the ceramics of the base material 5 as shown in FIG. 10 (c). The metal nanoparticles 1 can be fixed to the surface 7.

In the primary plating step, for example, as shown in the flowchart shown in FIG. 7, the base material 5 is immersed in the metal nanoparticle dispersion liquid, the third binder 2c is added to the metal nanoparticle dispersion liquid, and then the metal nanoparticle dispersion liquid is added. May be a step of forming the primary plating layer 4 on the base material 5 by stirring or allowing it to stand. In this case, the metal nanoparticles 1, the base material 5, and the third binder 2c are present in the metal nanoparticle dispersion liquid. Therefore, the third binder 2c is adsorbed on the ceramic surface 7 and the metal nanoparticles 1 of the base material 5 to fix the metal nanoparticles 1 on the ceramic surface 7. Further, the third binder 2c is adsorbed on the metal surface 9 and the metal nanoparticles 1 of the base material 5 to fix the metal nanoparticles 1 on the metal surface 9. By using the third binder 2c in this way, the primary plating layer 4 can be formed with one type of binder.

In the primary plating step, for example, as shown in the flowchart shown in FIG. 8, the third binder 2c is applied to the ceramic surface 7 and the metal surface 9 of the base material 5 by performing the surface treatment of the base material 5 using the third binder 2c. Even in the step of forming the primary plating layer 4 on the base material 5 by immersing the base material 5 in the metal nanoparticle dispersion liquid and stirring or allowing the metal nanoparticle dispersion liquid to stand. Good. In this case, in the surface treatment, the third binder 2c is adsorbed on the ceramic surface 7 and the metal surface 9 of the base material 5, and then the metal nanoparticles 1 are adsorbed on the third binder 2c in the metal nanoparticle dispersion liquid. Therefore, the condition for adsorbing the third binder 2c on the base material 5 and the condition for adsorbing the metal nanoparticles 1 on the third binder 2c can be changed.

The primary plating step can include a step of heat-treating the primary plated product 13 on which the primary plating layer 4 is formed. This makes it easier for the secondary plating layer 10 to precipitate with the primary plating layer 4 as the core. Before the heat treatment step, the primary plated product 13 can be washed and dried.
The heat treatment temperature can be, for example, 120 ° C. or higher and 400 ° C. or lower. The heat treatment time can be 1 minute or more and 30 minutes or less, preferably 10 minutes or more and 20 minutes or less. The heat treatment atmosphere may be in air, but is preferably an inert atmosphere such as nitrogen or argon.
Further, although the binder 2 may be thermally decomposed by the heat treatment, the adhesion strength of the primary plating layer 4 is maintained. Further, when the binder 2 is thermally decomposed, the thermal decomposition product of the binder 2 may be present at the interface between the base material 5 and the primary plating layer 4. When the binder 2 is a compound having a thiol group, it is considered that sulfur, which is a thermal decomposition product of the binder 2, or a compound containing sulfur is present at the interface between the base material 5 and the primary plating layer 4. When the binder 2 is a silane coupling agent, it is considered that a silicon compound, which is a thermal decomposition product of the binder 2, is present at the interface between the base material 5 and the primary plating layer 4.

3. 3. Secondary plating step The secondary plating step is a step of forming the secondary plating layer 10 by subjecting the base material 5 (primary plating product) on which the primary plating layer 4 is formed to electrolytic plating or electroless plating. By performing the secondary plating step, it is possible to produce a secondary plated product in which the metal plating layer 18 covering the base material 5 is sufficiently thick. By increasing the thickness of the metal plating layer 18, the conductivity of the metal plating layer 18 is improved. Further, since the metal plating layer 18 is electrically connected to the metal surface 9 of the base material 5, the metal plating layer 18 can be used as a terminal of the base material 5.
The secondary plating product can have a cross section as shown in FIG. 2A, for example.
The metal types of the primary plating layer 4 and the secondary plating layer 10 may be the same or different. When the metal types of the primary plating layer 4 and the secondary plating layer 10 are the same, it is considered that the primary plating layer 4 and the secondary plating layer 10 are integrated to form the metal plating layer 18. When the metal types of the primary plating layer 4 and the secondary plating layer 10 are different, the primary plating is performed on the portion of the metal plating layer 18 close to the base material 5 as in the metal plating product 13 shown in FIG. 2 (a). It is considered that the metal nanoparticles 1 constituting the layer 4 are present.

When the secondary plating step is performed by electroless plating, for example, the base material 5 on which the primary plating layer 4 is formed is immersed in a plating solution prepared by adding a reducing agent to an aqueous solution in which a metal compound is dissolved, and the plating solution is mixed. The secondary plating layer 10 can be formed by stirring or allowing the aqueous solution to stand at room temperature to 95 ° C. for 5 to 120 minutes. As a result, the secondary plating layer 10 can be deposited with the primary plating layer 4 as the core, and the gaps between the metal nanoparticles 1 can be filled with the secondary plating layer 10. As a result, the metal plating layer 18 can have high conductivity.
The metal type of the secondary plating layer 10 is, for example, Zn, Ni, Ag or Sn. An aqueous solution of a metal compound of this metal type can be used as a plating solution. The metal type of the secondary plating layer 10 is preferably nickel. As a result, the metal plating layer 18 can have heat resistance.
As the reducing agent, for example, sodium borohydride, hydrogen peroxide, sodium hypophosphite, hypophosphorous acid, hydrazine and the like can be used. Further, a complexing agent such as ethylenediamine or citric acid may be added to the plating solution. Further, a pH adjuster may be added to the plating solution.
The thickness of the secondary plating layer 10 is, for example, 50 nm to 3 μm.

When the secondary plating step is performed by electrolytic plating, for example, the base material 5 on which the primary plating layer 4 is formed is installed as a cathode in a plating solution which is an aqueous solution in which a metal compound is dissolved, and an electric current is passed through the base material 5. The secondary plating layer 10 can be formed on the primary plating layer 4.
The metal type of the secondary plating layer 10 is, for example, Zn, Ni, Ag or Sn. An aqueous solution of a metal compound of this metal type can be used as a plating solution. Further, a complexing agent such as ethylenediamine or citric acid may be added to the plating solution. Further, a pH adjuster may be added to the plating solution.

4. Tertiary plating step The tertiary plating step is a step of forming the tertiary plating layer 11 by subjecting the base material 5 (secondary plated product) on which the secondary plating layer 10 is formed to electrolytic plating or electroless plating. By performing the tertiary plating step, it is possible to produce a tertiary plated product in which the base material 5 is covered with the multi-layered metal plating layer 18. The tertiary plated product can have a cross section as shown in FIG. 2 (b), for example. The metal type of the secondary plating layer 10 may be different from the metal type of the tertiary plating layer 11. The metal type of the tertiary plating layer 11 is, for example, Zn, Ni, Ag or Sn.
In the tertiary plating step, electrolytic plating or electroless plating can be performed by the same method as in the secondary plating step.
The thickness of the tertiary plating layer 11 is, for example, 50 nm to 3 μm.

5. Metal-plated product The metal-plated product 13 of the present embodiment has a base material 5 having a ceramic surface 7 and a metal surface 9, and a metal-plated layer 18 provided on the ceramic surface 7 and the metal surface 9. The metal-plated product 13 has a compound having a thiol group, or a decomposition product or reaction product thereof, at the interface between the base material 5 and the metal-plated layer 18.
The metal-plated product 13 of the present embodiment can be produced by the above-mentioned metal plating method. Further, the metal plating layer 18 can be formed by the above-mentioned primary plating step and secondary plating step. Further, the metal plating layer 18 may be formed by a primary plating step, a secondary plating step, and a tertiary plating step. In this case, the metal plating layer 18 has a multi-layer structure. The metal-plated product 13 can have, for example, a cross section as shown in the cross-sectional views of FIGS. 1 (a) and 1 (b) and 2 (a) and 2 (b).

The metal-plated product 13 has a compound having a thiol group, or a decomposition product or reaction product thereof, at the interface between the base material 5 and the metal-plated layer 18. The compound containing a thiol group is a binder 2 used in the primary plating step, and remains at the interface between the base material 5 and the metal plating layer 18. The remaining binder 2 may be thermally decomposed or chemically reacted by heat treatment, self-heating of the metal-plated product 13, or the like. In this case, a decomposition product or reaction product of a compound having a thiol group is present at the interface between the base material 5 and the metal plating layer 18. The decomposition product or reaction product is, for example, sulfur, or a compound containing sulfur.

6. Resistor The resistor 15 of the present embodiment has a composite sintered body 28 having a ceramic phase 6 and a metal phase 8, and a metal plating layer 18 provided on the ceramic phase 6 and the metal phase 8. The metal plating layer 18 is a resistor terminal 20 that is electrically connected to the metal phase 8. The resistor 15 has a compound having a thiol group, or a decomposition product or reaction product thereof, at the interface between the composite sintered body 28 and the metal plating layer 18.
The resistor 15 limits or adjusts the amount of current. The resistor 15 is included in, for example, a neutral point grounding resistor, an inrush current limiting resistor, an exciting inrush current suppressing resistor, and the like.

The resistor 15 of the present embodiment can be manufactured by the above-mentioned metal plating method. Further, the metal plating layer 18 (resistor terminal 20) can be formed by the above-mentioned primary plating step and secondary plating step. Therefore, the adhesion strength of the metal plating layer 18 to the ceramic surface 7 and the metal surface 9 of the composite sintered body 28 can be increased, and the contact resistance between the composite sintered body 28 and the metal plating layer 18 can be made uniform. be able to. Further, the metal plating layer 18 may be formed by a primary plating step, a secondary plating step, and a tertiary plating step.
The resistor 15 can have, for example, a cross section as shown in the cross-sectional views of FIGS. 2 (a) and 2 (b).
The resistor 15 can have, for example, a nickel secondary plating layer 10 and a silver tertiary plating layer 11. When the resistor 15 has the nickel secondary plating layer 10, the heat resistance of the resistor terminal 20 can be improved, and by having the silver tertiary plating layer 11, the conductivity of the resistor terminal 20 is improved. Can be made to.

The resistor 15 has a compound having a thiol group, or a decomposition product or reaction product thereof, at the interface between the base material 5 and the metal plating layer 18. The compound containing a thiol group is a binder 2 used in the primary plating step, and remains at the interface between the base material 5 and the metal plating layer 18. The remaining binder 2 may be thermally decomposed or chemically reacted by heat treatment, self-heating of the resistor 15, or the like.

The metal plating layer 18 is a resistor terminal 20 that is electrically connected to the metal phase 8 of the composite sintered body 28. Therefore, a current can be passed through the composite sintered body 28 through the metal plating layer 18, and the amount of current can be limited or adjusted. Further, since the ceramic phase 6 of the composite sintered body 28 is an insulator or a high resistance semiconductor and the metal phase 8 is a conductor, the mixing ratio of the ceramics and the metal, the shape and size of the metal phase 8 and the like can be adjusted. By doing so, it is possible to control the electric resistance value of the composite sintered body 28.
The resistor 15 can have two resistor terminals 20a and 20b (metal plating layer 18) as shown in the perspective view of FIG. 3A. When a potential difference is generated between the resistor terminals 20a and 20b, a current can be passed through the metal phase 8 of the composite sintered body 28. Since the composite sintered body 28 has a structure in which the particulate metal phase 8 is dispersed and contacted in the ceramic phase 6 which is a matrix, it is considered that the current flows in the composite sintered body 28 through a complicated current path. ..

When a large current flows through the composite sintered body 28, the composite sintered body 28 self-heats and becomes hot. Therefore, the temperature of the resistor terminal 20 (metal plating layer 18) is also increased. Therefore, due to the difference in the coefficient of thermal expansion or the like, a stress that tends to peel off acts between the resistor terminal 20 and the composite sintered body 28. However, in the resistor 15 of the present embodiment, since the metal plating layer 18 is formed by the above-mentioned metal plating method of fixing the metal nanoparticles 1 to the ceramic surface 7 and the metal surface 9 by the binder 2, the resistor is formed. Even when 15 self-heats and becomes high in temperature, it is possible to prevent the resistor terminal 20 from peeling off from the composite sintered body 28. This was demonstrated by experiments conducted by the inventors.

A resistor 25 can be manufactured by using a plurality of resistors 15. The resistor 25 can have a structure in which a plurality of resistors 15 are laminated as shown in FIG. 3B, for example. The resistor terminal 20 can function as a terminal for electrically connecting two adjacent resistors 15 or a terminal for connecting the resistor 15 and the connection terminal 21.
The plurality of stacked resistors 15 may be connected in series as in the resistor 25 shown in FIG. 3 (b). Further, the plurality of stacked resistors 15 may be connected in parallel. Further, the resistor 25 may include a resistor 15 connected in parallel and a resistor 15 connected in series.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
[Metal plating of composite sintered body]
A composite sintered body obtained by mixing glass powder and nichrome powder at 70:30 and sintering them was used as a base material. A metal plating layer was formed on the surface of this composite sintered body.
<Example 1>
(1) Preparation step After adding 0.7 mL of silver nitrate (manufactured by Wako Pure Chemical Industries, Ltd.) 0.1 M aqueous solution to 100 mL of ultrapure water, 1 mL of sodium hydride (manufactured by Wako Pure Chemical Industries, Ltd.) 2 weights % Aqueous solution was added, and the mixture was stirred with a magnetic stirrer for 1 hour (500 rpm) to obtain a silver nanoparticle dispersion (hereinafter referred to as Ag dispersion).

(2) Primary Plating Step The first binder was modified on the surface of the composite sintered body by immersing the composite sintered body in an aqueous solution of mercaptopropyltrimethoxysilane (first binder) and allowing it to stand for 1 hour. Then, the composite sintered body was recovered, washed thoroughly with water, and then dried at 80 ° C. for 15 minutes. To the obtained binder-modified composite sintered body, 50 mL of Ag dispersion, 2.3 mL of 0.1 M aqueous solution of hydrochloric acid, and 0.25 mL of 10 mM aqueous solution of aminoethanethiol hydrochloride (second binder) were added to room temperature. The mixture was stirred (100 rpm) with a mix rotor for 3 hours. Then, the primary plated product was collected, washed thoroughly with water, and then vacuum dried.

(3) Secondary plating step 50 ml of ultrapure water, 1.65 mL of silver nitrate 0.1 M aqueous solution, 67 μL of ethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd.), and 5.7 mL of Rochelle salt (Wako Pure Chemical Industries, Ltd.) A 5 wt% aqueous solution was added to prepare an electroless silver plating solution. The primary plating product was put into this plating solution, and the mixture was stirred (100 rpm) with a mix rotor. The secondary plating was collected, washed thoroughly with water, and then vacuum dried.
(4) Heat Treatment Step The secondary plated product is heated in a tabletop muffle furnace (manufactured by Denken Co., Ltd., trade name "KDF P70") at 250 ° C. for 15 minutes in a nitrogen atmosphere to obtain the metal plated product according to Example 1. It was.

<Example 2>
A metal-plated product according to Example 2 was obtained in the same manner as in Example 1 except that the following (2-1) primary plating step was executed instead of the (2) primary plating step in Example 1.
(2-1) Primary Plating Step 0.25 mL of 3-glycidyloxypropyltrimethoxysilane (manufactured by Sigma Aldrich) (first binder) while stirring (500 rpm) 50 mL of a 1 wt% aqueous solution of acetic acid with a magnetic stirrer. ) Was slowly added dropwise to prepare an aqueous solution of glycidyloxypropyltrimethoxysilane. The first binder was modified on the surface of the composite sintered body by immersing the composite sintered body in the prepared solution and allowing it to stand for 1 hour. Then, the composite sintered body was recovered, washed thoroughly with water, and then dried at 80 ° C. for 15 minutes. To the obtained binder-modified composite sintered body, 50 mL of Ag dispersion, 2.3 mL of 0.1 M aqueous solution of hydrochloric acid, and 0.25 mL of 10 mM aqueous solution of aminoethanethiol hydrochloride were added, and the mixture rotor was mixed at room temperature for 3 hours. Stirred (100 rpm). Then, the primary plated product was collected, washed thoroughly with water, and then vacuum dried.

<Comparative example 1>
A metal-plated product according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the following (2-2) primary plating step was executed instead of the (2) primary plating step in Example 1.
(2-2) Primary plating step In a composite sintered body of φ30 × t2 mm, 50 mL of Ag dispersion, 2.3 mL of hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) 0.1 M aqueous solution, and 0.25 mL of aminoethane Add thiol hydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.) 10 mM aqueous solution (second binder) and stir with a mix rotor (manufactured by AS ONE, trade name "MIX-ROTAR VMR-5") for 3 hours at room temperature (100 rpm). did. Then, the primary plated product was collected, washed thoroughly with water, and then vacuum dried.

<Comparative example 2>
A metal-plated product according to Comparative Example 2 was obtained in the same manner as in Example 1 except that the following (2-3) primary plating step was executed instead of the (2) primary plating step in Example 1.
(2-3) Primary Plating Step 0.25 mL of 3-mercaptopropyltrimethoxysilane (Sigma Aldrich) while stirring (500 rpm) 50 mL of a 1 wt% aqueous solution of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) with a magnetic stirrer. (Manufactured by the same company) (first binder) was slowly added dropwise to prepare an aqueous solution of mercaptopropyltrimethoxysilane. The composite sintered body was immersed in the prepared solution and allowed to stand for 1 hour to modify the binder on the surface of the composite sintered body. Then, the composite sintered body was recovered, washed thoroughly with water, and then dried at 80 ° C. for 15 minutes. The obtained binder-modified composite sintered body was immersed in 50 mL of Ag dispersion and stirred (100 rpm) with a mix rotor at room temperature for 3 hours. Then, the primary plated product was collected, washed thoroughly with water, and then vacuum dried.

<Comparative example 3>
A metal-plated product according to Comparative Example 3 was obtained in the same manner as in Example 1 except that the following (2-4) primary plating step was executed instead of the (2) primary plating step in Example 1.
(2-4) Primary Plating Step The composite sintered body is immersed in a 0.5 wt% aqueous solution (first binder) of an aminopropyltrimethoxysilane aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) and allowed to stand for 1 hour to form a composite. The binder was modified on the surface of the sintered body. Then, the composite sintered body was recovered, washed thoroughly with water, and then dried at 80 ° C. for 15 minutes. The obtained binder-modified composite sintered body was immersed in 50 mL of Ag dispersion and stirred (100 rpm) with a mix rotor at room temperature for 3 hours. Then, the primary plated product was collected, washed thoroughly with water, and then vacuum dried.

<Comparative example 4>
A metal-plated product according to Comparative Example 4 was obtained in the same manner as in Example 1 except that the following (2-5) primary plating step was executed instead of the (2) primary plating step in Example 1.
(2-5) Primary Plating Step To the composite sintered body, 50 mL of Ag dispersion and 2.3 mL of 0.1 M aqueous hydrochloric acid solution were added, and the mixture was stirred (100 rpm) with a mix rotor for 3 hours. Then, the primary plated product was collected, washed thoroughly with water, and then vacuum dried.

<Evaluation>
The results of evaluating the metal-plated products according to Examples 1 and 2 and the metal-plated products according to Comparative Examples 1 to 4 are shown in the table. The evaluation of the coating state in the table was "○: good (the entire surface is covered with silver), ×: insufficient (some parts are not covered with silver)". The thickness of the plating layer of the metal plating was calculated to be 1 μm from the amount of metal used. The electrical resistance is measured 10 times using a digital multimeter (34970A, manufactured by Agilent) by pressing the electrode of a 4-probe probe for resistance measurement (manufactured by BAS) against the surface of the silver-plated material, and the average value thereof is measured. Calculated. The tape peeling test is performed by peeling off the adhesive tape attached to the metal plating, and the evaluation is "○: no plating peeling", △: some plating peeling, ×: plating peeling on the entire surface. There is. "

According to the metal plating methods according to Examples 1 and 2 and Comparative Examples 1 and 3, a metal-plated product could be uniformly obtained on the composite sintered body by using a binder.
When both the first binder and the second binder were used so as to bond to both the ceramic and the metal of Example 1, no plating peeling was observed in the tape peeling test, and the adhesion of the plating was good. In Example 1, it is considered that the hydrolyzable group contained in the first binder is bonded to the ceramic surface of the composite sintered body, and the thiol group contained in the first binder is bonded to the silver nanoparticles. Therefore, it is considered that the silver nanoparticles could be fixed on the ceramic surface of the composite sintered body by the first binder. Further, it is considered that one of the amino group and the thiol group contained in the second binder is bonded to the metal surface of the composite sintered body and the other is bonded to the silver nanoparticles. Therefore, it is considered that the silver nanoparticles could be fixed on the metal surface of the composite sintered body by the second binder.

In Example 2, peeling of the plating was observed in a part of the tape peeling test, but the adhesion of the plating was relatively good.
In Example 2, it is considered that the hydrolyzable group contained in the first binder is bonded to the ceramic surface of the composite sintered body, and the glycidyl group contained in the first binder is bonded to the silver nanoparticles. Therefore, it is considered that the silver nanoparticles could be fixed on the ceramic surface of the composite sintered body by the first binder. Further, it is considered that one of the amino group and the thiol group contained in the second binder is bonded to the metal surface of the composite sintered body and the other is bonded to the silver nanoparticles. Therefore, it is considered that the silver nanoparticles could be fixed on the metal surface of the composite sintered body by the second binder.

In Comparative Example 1, since the first binder was not used, it is considered that the silver nanoparticles could not be fixed on the ceramic surface of the composite sintered body, and as a result, it is considered that the peeling occurred in the tape peeling test.
In Comparative Example 2, since the second binder was not used, it is considered that the silver nanoparticles could not be fixed on the metal surface of the composite sintered body, and as a result, it is considered that the coating state of the metal plating was insufficient. ..
In Comparative Example 3, since the second binder was not used, it is considered that the silver nanoparticles could not be fixed on the metal surface of the composite sintered body, and as a result, it is considered that the peeling occurred in the tape peeling test.
In Comparative Example 4, since the first and second binders were not used, it is considered that the silver nanoparticles could not be fixed on the surface of the composite sintered body, and as a result, the coating state of the metal plating was insufficient. Conceivable.

[Metal plating with excellent heat resistance]
A composite sintered body obtained by mixing and sintering ceramic powder obtained by crushing non-standard roof tiles and nichrome powder at 70:30 was used as a base material. A metal plating layer was formed on the surface of this composite sintered body.
<Example 3>
(1) Preparation step After adding 1.41 mL of palladium chloride (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) 1 wt% aqueous solution to 100 mL of ultrapure water, 1 mL of sodium hydride (manufactured by Wako Pure Chemical Industries, Ltd.) 2 weight % Aqueous solution was added, and the mixture was stirred with a magnetic stirrer (500 rpm) for 12 hours to obtain a palladium nanoparticle dispersion (hereinafter referred to as Pd dispersion).

(2) Primary Plating Step The first binder was modified on the surface of the composite sintered body by immersing the composite sintered body having a diameter of 30 × t2 mm in an aqueous solution of mercaptopropyltrimethoxysilane (first binder) and allowing it to stand for 1 hour. Then, the composite sintered body was recovered, washed thoroughly with water, and then dried at 80 ° C. for 15 minutes. To the obtained binder-modified composite sintered body, 50 mL of Pd dispersion and 0.5 mL of p-aminothiophenol (manufactured by Wako Pure Chemical Industries, Ltd.) 10 mM ethanol solution were added, and the mixture was stirred for 3 hours. By such a primary plating step, a primary plating layer composed of Pd nanoparticles was formed, and a primary plated product was obtained.

(3) Secondary plating step In 100 ml of ultrapure water, 3.9 g of nickel sulfate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and 4.0 g of sodium hypophosphate monohydrate (Wako Pure Chemical Industries, Ltd.) After adding 3.1 g of malonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 3.1 g of malonic acid (manufactured by Wako Pure Chemical Industries, Ltd.), adjust the pH to 5.5 with 25% aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.) to make electroless nickel. A plating solution was prepared. Nickel plating was performed by putting the primary plating product in a plating solution and allowing it to stand at 60 ° C. for 11 minutes. The secondary plating was collected and washed thoroughly with water. The film thickness of the secondary plating layer was about 1 μm.

(4) Tertiary plating step In 100 ml of ultrapure water, 3.8 g of silver nitrate, 7.5 g of potassium cyanide (manufactured by Wako Pure Chemical Industries, Ltd.), and 1.5 g of potassium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) Was added to adjust the electrolytic silver plating solution. Next, the secondary plating product (cathode) on which the secondary plating layer is formed and the silver wire (anode) are immersed in the prepared plating solution, and a DC current ^{of 15 mA / cm 2 is passed between the anode and the cathode.} The composite sintered body was electroplated. A tertiary plating layer made of silver was formed by this tertiary plating step, and the metal-plated product of Example 3 was obtained. The film thickness of the tertiary plating layer was about 1 μm.

[Evaluation of heat resistance characteristics of metal plated products]
The prepared metal-plated product of Example 3 was held at 800 ° C. for 15 minutes and heat-treated. Then, the electrical resistance value, the tape peeling test, and the stud pull peeling strength measurement were performed on the metal-plated material after cooling.
When the electric resistance value of the composite sintered body was measured, it was 0.92Ω. This measured value was almost the same as the electric resistance value of the composite sintered body before the heat treatment. Therefore, it was found that the contact resistance between the metal-plated layer and the composite sintered body did not change even when the metal-plated product was heat-treated at 800 ° C.

The tape peeling test was performed by peeling the adhesive tape attached to the metal plating layer from the metal plating. In this test, the metal plating layer did not adhere to the adhesive tape and peel off from the composite sintered body. Therefore, it was found that even if the metal-plated product is heat-treated at 800 ° C., the adhesion strength of the metal-plated layer to the composite sintered body is high.

In the stud pull peeling strength measurement, a tensile load is applied to the stud pin adhered to the metal plating layer with an epoxy resin adhesive (Quick 5, manufactured by Konishi) on the metal plating, and the metal plating layer is released from the composite sintered body. The tensile load to be peeled off was measured. From this measurement, the adhesion strength of the metal plating layer was 1580 N / cm ² . Therefore, it was found that the adhesion strength of the metal plating layer to the composite sintered body was high even when the metal plating was heat-treated at 800 ° C.
Therefore, it was found that a metal-plated product having a heat resistance of 800 ° C. can be produced by the metal plating method of the present invention.

1: Metal nanoparticles 2: Binder 2a: 1st binder 2b: 2nd binder 2c: 3rd binder 4: Primary plating layer 5: Base material 6: Ceramic phase 7: Ceramic surface 8: Metal phase 9: Metal surface 10: Secondary plating layer 11: Tertiary plating layer 13: Metal plating 15, 15a to 15c: Resistor 18: Metal plating layer 20, 20a to 20f: Resistor terminals 21, 21a, 21b: Connection terminal 25: Resistor 26: Insulation plate 27: Conductive plate 28: Composite sintered body

Claims (4)

A primary plating step of forming a primary plating layer composed of a plurality of metal nanoparticles on the base material by fixing the plurality of metal nanoparticles to the surface of the base material using the first and second binders is included.
The base material has a ceramic surface and a metal surface, and has a ceramic surface and a metal surface.
The primary plating step is a step of forming a primary plating layer using a first binder that fixes a part of a plurality of metal nanoparticles to the ceramic surface and a second binder that fixes other metal nanoparticles to the metal surface. And
The first binder is a silane coupling agent having a thiol group, a disulfide group, an amino group or a glycidyl group.
The second binder is an organic compound having a first functional group adsorbed on the metal nanoparticles and a second functional group adsorbed on the metal surface.
A metal plating method characterized in that the first and second functional groups are a thiol group, a disulfide group, an amino group or a glycidyl group. The base material is a composite sintered body having a ceramic phase and a metal phase.
The ceramic surface is the ceramic phase.
The metal surface is the metal phase.
The ceramic phase is an inorganic oxide phase of Li, Be, B, N, F, Na, Mg, Al, Si, P, K, Ca, Ti, Cu, Zn, Y, Zr, Nb, Ba. The metal plating method according to claim 1 , which comprises oxides of one or a plurality of elements. The metal plating method according to claim 1 or 2 , further comprising a secondary plating step of forming a secondary plating layer by electroplating or electroless plating a base material on which a primary plating layer is formed. The metal plating method according to claim 3 , further comprising a tertiary plating step of forming a tertiary plating layer by electroplating or electroless plating a base material on which a secondary plating layer is formed.

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