COMPOSITE MATERIAL, TERMINAL AND METHOD FOR MANUFACTURING TERMINAL

Abstract

There is provided a composite material used in a manufacture of a terminal having a soldering portion and a terminal mating portion, that is a composite material in which a metal coating containing at least one of silver and tin and a composite coating composed of a silver layer containing carbon particles are provided on a base material, wherein there are a portion where the metal coating is exposed and a portion where the composite coating is exposed.

Claims

1. A composite material used in a manufacture of a terminal having a soldering portion and a terminal mating portion, that is a composite material in which a metal coating containing at least one of silver and tin and a composite coating composed of a silver layer containing carbon particles are provided on a base material, wherein there are a portion where the metal coating is exposed and a portion where the composite coating is exposed.

2. The composite material according to claim 1, wherein the portion where the metal coating is exposed corresponds to the soldering portion in the terminal, and the portion where the composite coating is exposed corresponds to the terminal mating portion in the terminal.

3. A method for manufacturing a terminal, the method including: processing the composite material according to claim 1 into a shape of a terminal.

4. A terminal, which is a terminal having a coating on a base material and having a soldering portion and a terminal mating portion, the coating including a metal coating containing at least one of silver and tin on the base material, and a composite coating composed of a silver layer containing carbon particles on the base material, wherein a portion where the metal coating of the terminal is exposed constitutes the soldering portion, and a portion where the composite coating of the terminal is exposed constitutes the terminal mating portion.

5. The terminal according to claim 4, wherein the terminal is a male terminal that is adapted to mate with a female terminal having a receiving portion.

6. The terminal according to claim 4 or 5, wherein the metal coating is a silver coating composed of silver on an entire surface layer of the base material, and the composite coating is provided on a part of the silver coating.

7. The terminal according to claim 6, wherein a thickness of the metal coating is 0.01 to 2.0 m.

8. The terminal according to claim 4, wherein a proportion of the carbon particles on a surface of the composite coating is 1 to 80 area %.

9. The terminal according to claim 4, wherein a thickness of the composite coating is 0.5 to 15 m.

10. The terminal according to claim 4, wherein an underlayer composed of at least one selected from the group consisting of Cu, Ni, Sn, and Ag is provided on the base material, and the metal coating and composite coating are provided on the underlayer.

11. The terminal according to claim 4, further having a spacer portion that sets apart between the soldering portion and the terminal mating portion.

12. A method for manufacturing a terminal, which is a method including: forming a metal coating containing at least one of silver and tin, and a composite coating composed of a silver layer containing carbon particles on a base material; and processing an obtained composite material into a shape of a terminal, wherein a portion where the metal coating of the terminal is exposed constitutes a soldering portion, and a portion where the composite coating of the terminal is exposed constitutes a terminal mating portion.

13. A method for manufacturing a terminal, which is a method including: processing a base material into a shape of a terminal; and forming a metal coating containing at least one of silver and tin, and a composite coating composed of a silver layer containing carbon particles on the processed base material, wherein a portion where the metal coating of the terminal is exposed constitutes a soldering portion, and a portion where the composite coating of the terminal is exposed constitutes a terminal mating portion.

14. A method for manufacturing a terminal, which is a method including: forming a silver coating composed of silver on an entire surface layer of a base material; forming a composite coating composed of a silver layer containing carbon particles on a part of the silver coating; and processing an obtained composite material into a shape of a terminal, wherein a portion where the silver coating of the terminal is exposed constitutes a soldering portion, and a portion where the composite coating of the terminal is exposed constitutes a terminal mating portion.

15. A method for manufacturing a terminal, which is a method including: processing a base material into a shape of a terminal; forming a silver coating composed of silver on an entire surface layer of the processed base material; and forming a composite coating composed of a silver layer containing carbon particles on a part of the silver coating, wherein a portion where the silver coating of the terminal is exposed constitutes a soldering portion, and a portion where the composite coating of the terminal is exposed constitutes a terminal mating portion.

16. The method for manufacturing a terminal according to claim 12, wherein the terminal is a male terminal to be mated with a female terminal having a receiving portion.

17. The method for manufacturing a terminal according to claim 14, wherein at least one of a part of the exposed portion of the silver coating and a part of the exposed portion of the composite coating further constitutes a spacer portion that sets apart between the soldering portion and the terminal mating portion.

18. The method for manufacturing a terminal according to claim 14, wherein a thickness of the silver coating is 0.01 to 2.0 m.

19. The method for manufacturing a terminal according to claim 14, the method including: forming an underlayer composed of at least one selected from the group consisting of Cu, Ni, Sn, and Ag on an entire surface layer of the base material; and forming the silver coating on an entire surface of the underlayer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 is a schematic view of a vertical cut section of a composite material according to the present invention.

[0046] FIG. 2 is a schematic view illustrating a portion where the metal coating 14 is exposed (exposed metal coating portion 18) in the embodiment of FIG. 1(b) as an example.

[0047] FIG. 3 is a schematic view of a vertical cut section of a composite material having a spacer portion according to the present invention.

[0048] FIG. 4 is a schematic view of the shape of a terminal as viewed from above (from a viewpoint where the composite coating is visible) according to one embodiment of the present invention.

[0049] FIG. 5 is a schematic view of a vertical cut section of the terminal having a spacer portion according to the present invention.

[0050] FIG. 6 is a schematic view of a vertical cut section of the terminal with a casing member attached thereto according to the present invention.

[0051] FIG. 7 is a schematic view of a vertical cut section of a male terminal and a female terminal.

DETAILED DESCRIPTION OF THE INVENTION

[0052] Hereinafter, an embodiment of the present invention will be described.

[Composite Material]

[0053] The composite material of the present invention is configured in such a manner that a metal coating containing at least one of silver and tin and a composite coating composed of a silver layer containing carbon particles are formed on a base material, and that there are a portion where the metal coating is exposed and a portion where the composite coating is exposed. The composite material is used to manufacture a terminal having a soldering portion and a terminal mating portion. Hereinafter, each component of this composite material will be described with reference to FIG. 1, which is a schematic view of the vertical cut section of the composite material. FIG. 1 illustrates two typical embodiments of a composite material 10 of the present invention.

[0054] As a constituent material of a base material 12 on which metal coating and composite coating are formed, it is suitable to use a material having an electrical conductivity required for materials of sliding electrical contact parts such as switches and connectors, and from the viewpoint of a cost, Cu (copper) and Cu alloys are preferable as the constituent materials. The Cu alloy is preferably an alloy composed of Cu and at least one selected from the group consisting of Si (silicon), Fe (iron), Mg (magnesium), P (phosphorus), Ni (nickel), Sn (tin), Co (cobalt), Zn (zinc), Be (beryllium), Pb (lead), Te (tellurium), Ag (silver), Zr (zirconium), Cr (chromium), Al (aluminum) and Ti (titanium), and inevitable impurities, from the viewpoint of electrical conductivity and strength. An amount of Cu in the Cu alloy is preferably 85 mass % or more, and more preferably 92 mass % or more (the amount of Cu is preferably 99.95 mass % or less).

[0055] The thickness of the base material 12 is not particularly limited, but from the viewpoint of responding to the recent trend toward smaller terminals, it is preferably 0.05 to 1 mm, and more preferably 0.1 to 0.6 mm. The base material 12 typically has a flat shape (such as a flat plate shape), and after the metal coating 14 and the composite coating 16 are formed to constitute the composite material 10, the composite material 10 is molded into the shape of a terminal, which is the intended use of the composite material 10. Conversely, the base material 12 may be machined into the shape of a terminal and then the metal coating 14 and the composite coating 16 may be formed thereon. The shape of the composite material 10 is typically substantially the same as that of the base material 12, that is, a flat plate shape. As described below, the composite material 10 of the present invention has a portion with excellent solder wettability and a portion with excellent micro-friction wear properties and a low coefficient of friction, and is therefore suitable as a material for a terminal having a soldering portion and a terminal mating portion.

[0056] The composite material 10 of the present invention may have a configuration in which an underlayer (not illustrated in FIG. 1) is formed on a base material, and the metal coating 14 and composite coating 16 are formed on the underlayer. Particularly, when the metal coating 14 is a thin layer having a thickness of 0.1 m or less, it is preferable to provide the underlayer from the viewpoint of the heat resistance of the composite material 10. The constituent metal of the underlayer is at least one metal or alloy selected from the group consisting of Cu, Ni, Sn, and Ag. The underlayer may be a single layer composed of Cu, Ni, Sn, Ag, or an alloy thereof, or a layer composed of a combination of these (a laminate structure), and the formation of the underlayer may be performed on an entire surface layer of the base material, or on only a part of it, depending on the application of the composite material 10 to be manufactured. Further, from the viewpoint of manufacturability of the composite material 10, the constituent metal of the underlayer is preferably at least one metal or alloy selected from the group consisting of Cu, Ni, and Ag.

[0057] For example, for the purpose of preventing copper in the base material 12 from diffusing to and reaching the surface of the metal coating 14 or the composite coating 16 and deteriorating the electrical conductivity, it is preferable to form an underlayer composed of Ni. When the base material 12 is a copper alloy containing zinc, such as brass, for the purpose of preventing the zinc in the base material 12 from diffusing to and reaching the surface of the metal coating 14 or the composite coating 16, it is preferable to form an underlayer composed of Cu. For the purpose of improving the adhesion of the metal coating 14 or the composite coating 16 to the base material 12, it is preferable to form an underlayer composed of Ag. The thickness of the underlayer is not particularly limited, but from the viewpoints of exhibiting function and cost, it is preferably 0.05 to 2 m, and more preferably 0.15 to 1 m.

[0058] In the composite material of the present invention, the metal coating 14 is formed on the base material 12 or on the underlayer described above. The metal coating 14 contains at least one of silver and tin. More specifically, the metal coating 14 is a coating composed of a single metal, for example, silver or tin, or a coating composed of an alloy of silver and tin. The metal and the alloy may contain inevitable impurities.

[0059] Both silver and tin are metals with excellent solder wettability, and therefore the metal coating 14 is suitable for use as a soldering portion of a terminal. Tin is particularly excellent in terms of solder wettability. On the other hand, when forming the metal coating composed of tin, there is a problem that whiskers are formed (which can cause short circuits), and in order to prevent this, an additional step such as reflow (heating) treatment to reduce internal stress is required. Silver does not have as good a solder wettability as tin, but the solder wettability of silver is still sufficient for practical use, and manufacture is easy through a simple step without whisker problem, and further silver is superior to tin in terms of heat resistance and electrical conductivity.

[0060] The metal coating 14 may be formed on the entire surface layer of the base material 12, or may be formed on only a part of it. The thickness of the metal coating 14 is not particularly limited as long as it exhibits good solder wettability, but is preferably 0.01 to 2.0 m. When taking a cost into consideration, the thickness is more preferably 0.01 to 0.8 m, even more preferably 0.015 to 0.6 m, and particularly preferably 0.02 to 0.2 m.

[0061] The composite coating 16 constituting the composite material of the present invention is composed of a silver layer containing carbon particles. The composite coating 16 may be formed directly on the base material 12 (e.g., the configuration in FIG. 1(a)), or may be formed on a part of the metal coating 14 formed on the base material (e.g., the configuration in FIG. 1(b)). In the silver layer constituting the composite coating 16, carbon particles are dispersed (preferably substantially uniformly) in a matrix composed of silver.

(Carbon Particles)

[0062] Since the composite coating 16 contains carbon particles, the coating has excellent micro-friction wear properties and a low coefficient of friction. From the viewpoint of exhibiting such functions, the carbon particles are preferably graphite particles. From the viewpoint of the micro-friction wear properties and low coefficient of friction of the composite coating 16, an average primary particle size of the carbon particles is preferably 0.5 to 15 m, and more preferably 1 to 10 m. The average primary particle size is an average value of a long diameter of the particles, and the long diameter is defined as a length of a longest line that can be drawn within a particle in an image (plane) of a carbon particle in the composite coating 16 of the composite material observed at an appropriate observation magnification. The long diameter is determined for 50 or more particles. Further, the shape of the carbon particles is not particularly limited and may be approximately spherical, flaky, or amorphous. However, from the viewpoint of improving the micro-friction wear properties and reducing the coefficient of friction of the composite material by smoothing the surface of the composite coating 16, a flaky shape is preferable.

(Vickers Hardness)

[0063] The composite coating 16 of the composite material 10 of the present invention preferably has a high hardness. Specifically, its Vickers hardness Hv is preferably 100 or more, and more preferably 120 to 230. Such a high hardness makes the composite coating 16 less likely to be scraped off, and gives the composite material 10 particularly excellent micro-friction wear properties.

(Carbon Content and Area Percentage)

[0064] The composite coating 16 in the embodiment of the composite material 10 of the present invention contains carbon particles as described above, and the carbon content in the composite coating 16 is preferably 1 to 50 mass %, more preferably 1.5 to 40 mass %, and even more preferably 2 to 35 mass %, from the viewpoints of the micro-friction wear properties, low coefficient of friction, and electrical conductivity of the composite material 10.

[0065] Further, the percentage (area percentage) of the carbon particles on the surface of the composite coating 16 containing carbon particles is an index of the micro-friction wear properties and low coefficient of friction, and from the viewpoint of a balance between these two properties and the electrical conductivity, the area percentage is preferably 1 to 80 area %, and more preferably 12 to 50 area %. The surface of the composite coating 16 may contain carbon particles that are merely adhered and easily fall off. In this case, the area percentage of the carbon particles on the surface of the composite coating 16 is obtained after performing ultrasonic cleaning treatment similar to that described in the section (Treatment for partially removing carbon particles from the surface of the composite coating) described later. The method for measuring the area percentage will be described in detail in the examples.

(Elemental Composition of the Composite Coating)

[0066] The elemental composition of the composite coating 16 in the embodiment of the composite material 10 of the present invention typically consists essentially of silver and carbon (for example, when EDX analysis is performed using an energy dispersive X-ray analyzer, the sum of the silver content and the carbon content in the composite coating 16 is 100 mass %).

(Thickness of the Composite Coating)

[0067] The thickness of the composite coating 16 is not particularly limited, but it is preferable that the composite coating 16 has a minimum thickness in terms of micro-friction wear properties, a low coefficient of friction, and electrical conductivity. If the thickness is too large, the effect of the composite coating 16 becomes saturated and a raw material cost increases. From the above viewpoints, the thickness of the composite coating 16 is preferably 0.5 to 15 m, more preferably 0.6 to 8 m, and even more preferably 0.7 to 6 m. The thickness of the composite coating 16 is measured by a fluorescent X-ray thickness meter, and the details of a measurement method will be described in the examples.

[0068] As described above, the composite material 10 of the present invention has a configuration in which the metal coating 14 and the composite coating 16 are formed on the base material 12, and the composite material 10 has a portion where the metal coating 14 is exposed. Exposed means that the portion is not covered with the composite coating 16 or any other layer, or in other words, that the portion constitutes a part of the outermost surface of the composite material 10. Taking the embodiment of FIG. 1(b) as an example, the portion where the metal coating 14 is exposed (metal coating exposed portion 18) is illustrated in FIG. 2.

[0069] The portion 18 where the metal coating is exposed has good solder wettability and therefore functions well as a soldering portion in the terminal having a soldering portion and a terminal mating portion. That is, when the composite material 10 is processed into a terminal, the portion 18 where the metal coating is exposed, is preferably used as the soldering portion.

[0070] The composite material 10 has a portion where the composite coating 16 is exposed. Exposed means that the portion is not covered with the metal coating 14 or any other layer, or in other words, that the portion constitutes a part of the outermost surface of the composite material 10. This portion 20 where the composite coating is exposed has excellent micro-friction wear properties and a low coefficient of friction, and therefore functions satisfactorily as a terminal mating portion in the terminal having the soldering portion and the terminal mating portion. That is, when the composite material 10 is processed into a terminal, it is preferable to use the portion 20 where the composite coating is exposed as a terminal mating portion.

[0071] As described above, the composite material 10 of the present invention is suitable as a material for a terminal having a soldering portion and a terminal mating portion. In such a terminal, as described below, the spacer portion may be present to set apart between the soldering portion and the terminal mating portion.

[0072] In this case, as illustrated in FIG. 3, the entire or a part of a portion 22 extending from a part of the exposed metal coating portion 18 to a part of the exposed composite coating portion 20 is the spacer portion. The spacer portion will be described in detail later in the description of the terminal of the present invention.

[0073] The composite material of the present invention described above is suitable for use in the manufacture of a terminal having a soldering portion and a terminal mating portion. A specific example of the terminal is a terminal for a printed circuit board.

[Method for Manufacturing the Composite Material]

[0074] A method for manufacturing the above-described composite material of the present invention will be described below.

[0075] As described above, the base material is preferably Cu or Cu alloy as its constituent material, and the Cu alloy is preferably an alloy composed of Cu and at least one selected from the group consisting of Si, Fe, Mg, P, Ni, Sn, Co, Zn, Be, Pb, Te, Ag, Zr, Cr, Al, and Ti, and inevitable impurities, and the amount of Cu in the Cu alloy is preferably 85 mass % or more, more preferably, 92 mass % or more (the amount of Cu is preferably 99.95 mass % or less), the thickness of the base material is preferably 0.05 to 1 mm, more preferably 0.1 to 0.6 mm, and the shape of the base material is typically flat (such as a flat plate shape). Such a base material is commercially available and can be manufactured by a conventionally known method.

[0076] When forming the underlayer in the composite material of the present invention, the method for forming the underlayer is not particularly limited. As described above, examples of the constituent metal of the underlayer include at least one metal or alloy selected from the group consisting of Cu, Ni, Sn, and Ag, and from the viewpoint of manufacturability, at least one metal or alloy selected from the group consisting of Cu, Ni and Ag is preferable, and the thickness thereof is preferably 0.05 to 2 m, and more preferably 0.15 to 1 m.

[0077] For example, the underlayer can be formed by electroplating using a known method in a plating solution containing ions of the constituent metals of the underlayer. As described above, the underlayer may be formed on the entire surface layer of the base material, or may be formed on only a part of the surface layer of the base material.

[0078] The metal coating contains at least one of silver and tin as described above, and from the viewpoint of solder wettability, tin is preferable, and from the viewpoints of simplicity of the manufacturing step and heat resistance/electrical conductivity, silver is preferable. The thickness of the metal coating is preferably 0.01 to 2.0 m, more preferably 0.01 to 0.8 m, even more preferably 0.015 to 0.6 m, and particularly preferably 0.02 to 0.2 m.

[0079] The metal coating can be formed on the base material by a conventionally known method, for example, electroplating using a plating solution containing metal that constitute the metal coating, or vapor deposition. When a tin coating is formed, a reflow (heat) treatment is performed to remove internal stress and prevent whisker formation. It is also possible to form a coating composed of an alloy of silver and tin by laminating layers of these on the base material and then heating the layers.

[0080] The composite coating is composed of a silver layer containing carbon particles as described above, and the Vickers hardness Hv of the composite coating is preferably 100 or more, and more preferably 120 to 230. The carbon content in the composite coating is preferably 1 to 50 mass %, and more preferably 1.5 to 40 mass %, and even more preferably 2 to 35 mass %, and the percentage (area percentage) of the carbon particles on the surface of the composite coating is preferably 1 to 80 area %, and more preferably 12 to 50 area %, and the elemental composition of the composite coating typically consists essentially of silver and carbon, and the thickness of the composite coating is preferably 0.5 to 15 m, more preferably 0.6 to 8 m, and even more preferably 0.7 to 6 m.

[0081] The composite coating can be formed by a conventionally known method, and a typical method will be described below, that is a method of forming the composite coating by causing carbon particles to be entangled into a silver-plated film using electroplating.

(Silver Strike Plating)

[0082] Before forming the composite coating on the base material, it is preferable to form a very thin intermediate layer (silver strike plated layer) by silver strike plating to improve adhesion between the base material and the composite coating. When the underlayer is formed on the base material, the silver strike plating is applied to the underlayer (to improve adhesion between the underlayer and the composite coating). As a method for applying silver strike plating, any conventionally known method can be used without particular limitation as long as it does not impair the effects of the present invention. Further, as described above, even when the metal coating in the composite material is very thin, it shows excellent solder wettability. Therefore, when the metal coating is a silver coating, silver strike plating is applied to the portion where the metal coating is to be formed and the portion where the composite coating is to be formed, so that the metal coating composed of silver and the silver strike plated layer for forming a composite coating thereon can be formed simultaneously. This is extremely advantageous in terms of the simplicity of the manufacturing step. The silver strike plated layer is generally a thin layer, but in the present invention, it is preferable to adjust the thickness within a range of 0.01 to 2.0 m.

(Electroplating)

[0083] After the silver strike plated layer is formed, electroplating is performed using a silver plating solution containing carbon particles to form a silver matrix and to cause the carbon particles to be entangled in the silver matrix, thereby forming a composite coating containing carbon particles in the silver layer on the base material. The composite coating may be formed directly on the base material, or may be formed on a part of the metal coating formed on the base material.

[0084] The silver plating solution contains silver ions, and a silver concentration in this silver plating solution is preferably 5 to 150 g/L, more preferably 10 to 120 g/L, and most preferably 20 to 100 g/L, from the viewpoints of the rate of formation of the composite coating and of suppressing unevenness in the appearance of the composite coating.

[0085] The silver plating solution contains carbon particles, the shape of which is not particularly limited and may be, as described above, substantially spherical, flaky, or amorphous, but is preferably flaky. The volume-based cumulative 50% particle size (D50) of the carbon particles, as measured by a laser diffraction/scattering particle size distribution analyzer, is preferably 0.5 to 15 m, and more preferably 1 to 10 m, from the viewpoint of ease of entanglement into the silver matrix. Further, it is preferable to subject the carbon particles to an oxidation treatment to remove lipophilic organic matters adsorbed on the surface of the carbon particles, thereby improving the dispersibility of the carbon particles in the silver plating solution. The specific method of the oxidation treatment is conventionally known.

[0086] Further, the carbon particles that have been subjected to the above-described oxidation treatment may be subjected to a surface treatment with a polymer, as needed. Thereby, the smoothness of the surface of the composite coating formed using the silver plating solution, can be improved.

[0087] Specifically, the carbon particles are mixed by stirring in water in the presence of the polymer. At this time, it is considered that the polymer adheres to the carbon particles due to the functional groups and three-dimensional structure of the polymer. After the above stirring and mixing, the mixture is filtered and filtered products (carbon particles surface-treated with polymer) may be cleaned with water.

[0088] A weight average molecular weight of the polymer (molecular weight in terms of standard polyethylene glycol and standard polyethylene oxide measured by GPC) is preferably 1,000 or more and 150,000 or less. Specific examples of the polymer include poly(diallyldimethylammonium chloride) and diallylamine hydrochloride-acrylamide copolymer.

[0089] When the carbon particles are surface-treated (when the carbon particles are stirred and mixed in the water in the presence of the polymer), the concentration of the carbon particles in the water is preferably 200 g/L or less (usually 10 g/L or more, more preferably, 50 to 120 g/L), the use amount of the polymer per 100 parts by mass of carbon particles is preferably 10 to 150 parts by mass (more preferably 20 to 100 parts by mass), a liquid temperature is preferably 15 C. or higher and 60 C. or lower, and a surface treatment (stirring and mixing) time is preferably 3 hours or higher and 30 hours or lower. Cleaning with water may be continued until the electrical conductivity of a filtrate becomes 10 uS/cm or less.

[0090] The concentration of the carbon particles in the silver plating solution is preferably 10 to 150 g/L, more preferably 15 to 120 g/L, and particularly preferably 30 to 100 g/L, from the viewpoint of the micro-friction wear properties and low coefficient of friction of the obtained composite material, and because there is a limit in the amount of carbon particles that can be introduced into the composite coating.

[0091] The silver plating solution preferably contains compound A represented by the following general formula (1). It is considered that compound A adsorbs on the surface of the deposited silver and inhibits the growth of silver crystals, thereby reducing a silver crystallite size in the composite coating that is formed by electroplating and increasing the hardness of the composite coating.

##STR00001##

[0092] In formula (1), m is an integer of 1 to 5; Ra is a carboxyl group; Rb is an aldehyde group, a carboxyl group, an amino group, a hydroxyl group, or a sulfonic acid group; Rc is hydrogen or an arbitrary substituent; and Ra and Rb may each independently be bonded to a benzene ring via at least one divalent group selected from the group consisting of O and CH2. Examples of the divalent group include CH.sub.2CH.sub.2O, CH.sub.2CH.sub.2CH.sub.2O, and (CH.sub.2CH.sub.2O) n (n is an integer of 2 or more).

[0093] In formula (1), when m is 2 or more, multiple Rb's may be the same or different, and when m is 3 or less, multiple Rc's may be the same or different. The arbitrary substituent of Rc includes an alkyl group having 1 to 10 carbon atoms, an alkylaryl group, an acetyl group, a nitro group, a halogen group, and an alkoxyl group having 1 to 10 carbon atoms.

[0094] The concentration of compound A in the silver plating solution is preferably 2 to 250 g/L, and more preferably 3 to 200 g/L, from the viewpoints of suppressing unevenness in the appearance of the composite coating and appropriately controlling the crystallite size of silver in the formed composite coating.

[0095] The silver plating solution used in the present invention preferably contains a complexing agent. The complexing agent complexes the silver ions in the silver plating solution, thereby enhancing the stability of the ions. As the complexing agent, from the viewpoint of the stability of the formed complex, a compound having a sulfonic acid group, for example, an alkylsulfonic acid having 1 to 12 carbon atoms, an alkanolsulfonic acid having 1 to 12 carbon atoms, and a hydroxyarylsulfonic acid are preferable.

[0096] Further, the silver plating solution may contain a brightener, a hardener, and a conductive salt. The solvent constituting the silver plating solution is mainly water. Water is preferrable because of its ability to dissolve (complexed) silver ions and other components contained in the plating solution, and because water poses little environmental burden. Further, a mixed solvent of water and alcohol may be used as a solvent.

[0097] The above-described silver plating solution is used to perform electroplating. The base material to be electroplated is the cathode. For example, a silver electrode plate that dissolves to provide silver ions, is the anode. The cathode and the anode are immersed in the silver plating solution (plating bath) and silver plating is performed by passing an electric current through them. The current density here is preferably 0.5 to 10 A/dm.sup.2, more preferably 1 to 8 A/dm.sup.2, and even more preferably 1 to 5 A/dm.sup.2, from the viewpoint of the formation rate of the composite coating and the suppression of unevenness in the appearance of the composite coating. The temperature (plating temperature) of the plating bath (silver plating solution) during electroplating is preferably 15 to 50 C., more preferably 20 to 45 C., from the viewpoints of plating production efficiency and preventing excessive evaporation of the solution. The silver plating time (time for applying electric current) can be appropriately adjusted depending on a desired thickness of the composite coating, but is typically in a range of 25 to 1800 seconds.

(Treatment for Partially Removing Carbon Particles from the Surface of the Composite Coating)

[0098] For example, on the surface of the composite coating formed on the base material by the electroplating described above, there are carbon particles that are entangled (embedded) in the silver matrix and are therefore difficult to fall off, and carbon particles that are adhered to the surface rather than entangled and are therefore more likely to fall off. The latter can contaminate equipment, for example during bending of the composite material. Therefore, it is preferable to remove such carbon particles by cleaning. One cleaning method is to subject the surface of the composite coating to ultrasonic cleaning. The ultrasonic cleaning is preferably performed at 20 to 100 kHz for 1 to 300 seconds. Another cleaning method is electrolytic cleaning, which is preferably performed at 1 to 30 A/dm.sup.2 for 10 to 300 seconds.

[Terminal]

[0099] Next, the terminal of the present invention will be described.

[0100] The terminal of the present invention is formed by forming a coating on the base material, and has a soldering portion and a terminal mating portion. The coating includes a metal coating containing at least one of silver and tin formed on the base material, and a composite coating including a silver layer containing carbon particles formed on the base material, and the portion where the metal coating of the terminal is exposed corresponds to the soldering portion, and the portion where the composite coating of the terminal is exposed corresponds to the terminal mating portion. The configuration of the terminal of the present invention will be described below.

[0101] The base material is the same as the base material in the composite material of the present invention, and Cu and Cu alloy are suitable as the constituent materials thereof. The Cu alloy is preferably an alloy composed of Cu and at least one selected from the group consisting of Si, Fe, Mg, P, Ni, Sn, Co, Zn, Be, Pb, Te, Ag, Zr, Cr, Al, and Ti, and inevitable impurities, and the amount of Cu in the Cu alloy is preferably 85 mass % or more, more preferably 92 mass % or more (the amount of Cu is preferably 99.95 mass % or less), and the thickness of the base material is preferably 0.05 to 1 mm, more preferably 0.1 to 0.6 mm.

[0102] The terminal of the present invention may have a configuration in which an underlayer is formed on the base material, and the metal coating and composite coating are formed thereon. The underlayer is the same as the underlayer in the composite material of the present invention, and the constituent metal thereof is at least one metal or alloy selected from the group consisting of Cu, Ni, Sn, and Ag, and from the viewpoint of manufacturability of the terminal, at least one metal or alloy selected from the group consisting of Cu, Ni and Ag is preferable, and the thickness thereof is preferably 0.05 to 2 m, more preferably 0.15 to 1 m.

[0103] The metal coating in the terminal of the present invention is the same as the metal coating in the composite material of the present invention, and contains at least one of silver and tin, with tin being preferable from the viewpoint of solder wettability, and silver being preferable from the viewpoints of simplicity of production step, heat resistance and electrical conductivity. The metal coating may be formed on an entire surface layer of the base material, or may be formed only on a part of the surface, and the thickness of the metal coating is preferably 0.01 to 2.0 m, more preferably 0.01 to 0.8 m, even more preferably 0.015 to 0.6 m, and particularly preferably 0.02 to 0.2 m.

[0104] The composite coating in the terminal of the present invention is the same as the composite coating in the composite material of the present invention, and is composed of a silver layer containing carbon particles. An average primary particle size of the carbon particles is preferably 0.5 to 15 m, and more preferably 1 to 10 m. The Vickers hardness Hv of the composite coating is preferably 100 or more, and more preferably 120 to 230. The carbon content in the composite coating is preferably 1 to 50 mass %, and more preferably 1.5 to 40 mass %, and even more preferably 2 to 35 mass %. The percentage (area percentage) of the carbon particles on the surface of the composite coating is preferably 1 to 80 area %, and more preferably 12 to 50 area %. The elemental composition of the composite coating typically consists essentially of silver and carbon, and the thickness of the composite coating is preferably 0.5 to 15 m, more preferably 0.6 to 8 m, and even more preferably 0.7 to 6 m.

[0105] As described above, the terminal mating portion in the terminal of the present invention is constituted by a portion where the composite coating of the terminal is exposed. Exposed means that the portion is not covered with a metal coating or other layer, or in other words, that the portion constitutes a part of an outermost surface of the terminal. Basically, the terminal mating portion is located at one end of the terminal. The surface of this terminal mating portion is constituted by the composite coating, and therefore has excellent micro-friction wear properties and a low coefficient of friction.

[0106] Specifically, a micro-friction wear property test was performed in the examples described below, and after 5,000 reciprocating sliding operations, the center of the sliding marks of the indented test piece and the flat test piece were observed at a magnification of 200 times using a microscope (VHX-1000 manufactured by Keyence Corporation). Then, it is confirmed that no base material is exposed from either of the sliding marks. The coefficient of friction measured by the method described in the examples below is 0.50 or less, preferably 0.40 or less, and more preferably 0.30 or less. The coefficient of friction is usually 0.01 or more.

[0107] The terminal mating portion is a laminate of the base material and the composite coating, or a laminate of the base material, the metal coating, and the composite coating (other layers may be present if there is a portion where the composite coating is exposed). FIG. 4 is a schematic view of the shape of the terminal as viewed from above (from a viewpoint where the composite coating is visible) according to one embodiment of the present invention.

[0108] Although details will be described later, the terminal is typically a set of a male terminal and a female terminal having a receiving portion that receives the terminal mating portion of the male terminal, and the terminal of the present invention is suitable as a male terminal. The terminal mating portion 30 in the terminal of the present invention is typically formed in a rod shape such as a pin or tab (such as a cylindrical or polygonal column shape), a convex shape, an elongated plate shape, or a combination of these shapes. In the embodiment illustrated in FIG. 4, the tip of a rectangular parallelepiped is rounded and slightly tapered (a type of the convex shape).

[0109] The surface of the terminal mating portion 30 is formed of the composite coating, but the solder wettability of this coating is lower than that of the metal coating. While the metal coating exhibits excellent solder wettability when solder is heated to about 250 C., the composite coating is barely wetted by solder at this temperature, but when heated to 350 C. or higher the composite coating exhibits solder wettability that is practically acceptable.

[0110] Next, the soldering portion of the terminal of the present invention will be described with reference to FIG. 4. A soldering portion 32 is constituted by a portion where the metal coating of the terminal is exposed. Exposed means that the portion is not covered with the composite coating or any other layer, or in other words, that the portion constitutes a part of the outermost surface of the terminal. Basically, the soldering portion 32 is located at the opposite end of the terminal mating portion 30. Since the metal coating contains at least one of silver and tin, which is a metal with excellent solder wettability, the soldering portion 32 exhibits excellent solder wettability equivalent to that of the prior art. Specifically, when performing a solder wettability test (a test for determining solder wettability after thermal aging) as described in the examples below, the soldering portion 32 shows a solder wetted area percentage of 80 area % or more. The solder wetted area percentage of the soldering portion 32 is preferably 90% or more, and more preferably 95% or more. Further, when the metal coating is substantially composed of silver, the soldering portion 32 exhibits excellent solder wettability since silver is a metal with excellent heat resistance. However, when the silver coating is a thin layer, such as 0.1 m or less, in order to achieve excellent solder wettability, it is preferable to form an underlayer to suppress atomic diffusion from the base material through to the silver coating surface.

[0111] The soldering portion 32 is typically a laminate of the base material and the metal coating (other layers may be present if there is a portion where the metal coating is exposed). The shape of the soldering portion 32 when the terminal of the present invention is viewed from above is, for example, a rod shape such as a round or square rod, a thin and long plate shape, or a combination of these shapes.

[0112] The terminal of the present invention may further include a spacer portion for setting apart between the soldering portion and the terminal mating portion. FIG. 5 is a schematic view illustrating a vertical cut section of the terminal having the spacer portion according to the present invention.

[0113] A casing member, which will be described later, may be attached to a spacer portion 34. The terminal of the present invention is manufactured, for example, by punching the composite material of the present invention (which has a metal coating and a composite coating on a base material), as described below. By this punching, the terminal mating portion 30, the soldering portion 32 and the spacer portion 34 are simultaneously formed. That is, they are typically formed as one unit. When the metal coating exposed portion 42 has only a minimum dimension required for the soldering portion and the composite coating exposed portion 44 has only a minimum dimension required for the terminal mating portion, there is no spacer portion. On the other hand, when the dimensions of the exposed metal coating portion 42 and/or the exposed composite coating portion 44 are designed to be longer than the minimum dimensions described above, the spacer portion 34 is formed. That is, the spacer portion 34 is composed of at least one of a part of the metal coating 38 and a part of the composite coating 40, and a part of the base material 36 corresponding to the above one of the parts. The part of the base material 36 corresponding to the above one of the parts refers to the part of the base material 36 that is vertically below the above one of the parts when the terminal is placed horizontally.

[0114] When the terminal of the present invention is bent at the spacer portion 34, it is possible to design products such as connectors having shapes different from those of straight terminals that are not bent. The spacer portion 34 is useful in terms of being able to have a casing member attached thereto, which will be described next, and in terms of the degree of freedom in a product design.

[0115] As described above, the casing member may be attached to the spacer portion 34. A schematic view of a vertical cut section of the terminal with a casing member attached thereto is illustrated in FIG. 6.

[0116] A casing member 50 is attached to the spacer portion 34. Typically, the casing member 50 has a box shape having an opening, and a wall surface facing the opening is provided with a plurality of holes through which the terminals 60 are inserted. The number of holes is appropriately adjusted depending on the application of the terminals. The soldering portion 32 of the terminal 60 is located on the outside of the box-shaped casing member 50, and the terminal mating portion 30 is located on the inside of the box-shaped casing member 50 (on the opening side as viewed from the hole). Further, a casing fixing portion X can be provided at the spacer portion 34 that is inserted through the hole of the casing member 50 to make it difficult for the terminal 60 to fall off from the casing member 50. Further, a terminal fixing portion Y that enables fixing to a female terminal, which will be described later, may be provided at the opening of the casing member 50.

[0117] The casing member 50 is made of an insulating material, and an example of such a material is resin.

[0118] As a specific embodiment of the terminal of the present invention, the terminal is typically a set of a male terminal and a female terminal, and the terminal of the present invention is preferably a male terminal. The male terminal and the female terminal will be described below with reference to FIG. 7 which is a schematic view of a vertical cut section of the male terminal and the female terminal.

[0119] A female terminal 70 has a receiving portion 72 formed in a shape to receive the terminal mating portion 30 of the male terminal 60, and has a fixing portion 74 therein for fixing the terminal mating portion 30 of the mated male terminal within the receiving portion 72 of the female terminal to pass electricity therethrough. Examples of the shape of the receiving portion 72 include a cylindrical shape and a box-like (rectangular parallelepiped) shape. The terminal mating portion 30 is fitted into the receiving portion 72, thereby establishing a physical and electrical connection therebetween. In order to achieve a good electrical connection, it is preferable that the receiving portion 72 and the terminal mating portion 30 are manufactured from the same material. Further, the shape of the fixing portion 74 and the method for fixing the terminal mating portion 30 are not particularly limited as long as they can fix the fitted terminal mating portion 30, and may be, for example, a claw shape or a spring.

[0120] Further, a casing member 76 may be attached to the female terminal 70. Typically, the casing member 76 has a box shape having an opening, and one wall surface is provided with a plurality of holes through which the female terminals 70 are inserted. The number of holes is appropriately adjusted depending on the application of the terminal. The receiving portion 72 of the female terminal 70 is located at the opening of the casing member 76. The casing member 76 may be provided with a terminal fixing portion P that engages with the terminal fixing portion Y of the male terminal 60 described above to fix the male terminal 60 and the female terminal 70 together. By both the male terminal 60 and the female terminal 70 having a casing member, a plurality of male terminals 60 and female terminals 70 can be aligned and mated with each other by aligning the casing members together, rather than aligning both small terminals.

[0121] The constituent material of the casing member 76 is the same as the constituent material of the casing member 50 of the male terminal 60. The casing members 76 and 50 are preferably made of a material capable of elastic deformation. In this case, by pushing the male terminal 60 and the female terminal 70 against each other so that the terminal mating portion 30 is fitted into the receiving portion 72, the casing members 76 and 50 are deformed, allowing the casing member 76 to enter inside the casing member 50 of the male terminal 60, and the two casing members are engaged and fixed at the fixing portions P and Y.

[0122] A terminal for a printed circuit board is given as a specific application of the terminal of the present invention having the soldering portion and the terminal mating portion described above.

[Method for Manufacturing the Terminal]

[0123] A method for manufacturing the terminal according to the present invention will now be described. In this manufacturing method, a metal coating containing at least one of silver and tin, and a composite coating composed of a silver layer containing carbon particles are formed on a base material. As described above, the terminal has the portion where the metal coating is exposed and the portion where the composite coating is exposed, and by designing the dimensions of at least one of these to be longer than the minimum dimensions of the soldering portion and the terminal mating portion respectively, the spacer portion is formed in the terminal.

[0124] As the method for manufacturing the terminal of the present invention, the following methods are given: a method of forming the metal coating and the composite coating on the base material that is not in the shape of the intended purpose (for example, a flat plate shape) to make it into a composite material and then processing it into the shape of a terminal (pre-coating formation); and a method of forming the metal coating or composite coating after processing the base material into the shape of a terminal (post-coating formation). These two techniques will be described below.

<Pre-Coating Formation>

[0125] In the technique of the pre-coating formation, the composite material of the present invention is first manufactured (the metal coating and the composite coating are formed on a flat plate-shaped base material). The composite material is then processed into a desired terminal shape by one or a combination of known processing techniques such as punching and bending.

<Post-Coating Formation>

[0126] In the technique of the post-coating formation, the base material is processed into a desired terminal shape by one or a combination of known processing techniques such as punching and bending. The base material thus shaped into a terminal is then subjected to the method of manufacturing a composite material of the present invention (formation of a metal coating and a composite coating (additionally forming an underlayer, etc., if necessary)).

[0127] Next, various configurations common to the pre-coating formation method and post-coating formation method will be described.

(Base Material, Formation of the Underlayer, Formation of the Metal Coating, Formation of the Composite Coating)

[0128] These are all similar to those explained in the explanation of the method for manufacturing a composite material of the present invention.

(Attachment of the Casing Member)

[0129] The casing member may be attached to the terminal formed by each technique. For example, as described above with reference to FIG. 6, in the case of the casing member having a wall surface facing the opening, on which a plurality of holes are provided through which the terminal of the present invention is inserted, for example, the casing member is manufactured by injection molding using a resin, and the terminals are inserted and pushed into the holes of the casing member. Thereby, there is provided a product in which the terminals are inserted through a plurality of holes in the casing member and fixed by the casing fixing portion X.

(when the Metal Coating is Silver Coating)

[0130] When the metal coating is a silver coating, the terminal of the present invention can be manufactured by a simple method as described below.

[0131] First, a silver coating composed of silver is formed on an entire surface layer of the base material (or processed into the shape of the terminal when the post-coating method is used), and then the composite coating is formed on a part of the silver coating (the portion corresponding to the portion that will become the terminal mating portion). With these two simple steps, silver coating and composite coating can be formed on the base material. On the other hand, when the metal coating is a tin coating, an additional treatment called a reflow treatment is required to prevent whiskers. Further, when the metal coating is a coating containing tin, such as a tin coating or a silver-tin alloy coating, the adhesion between the coating and the composite coating may not be sufficient, and it is preferable that the metal coating and the composite coating are each formed directly on the base material (or on the underlayer, when it is formed). In this case, when one coating is formed, an additional step needs to be performed as follows: a mask is applied to the portion where the other coating is to be formed, and the mask is then removed (peeled off) after the coating formation is completed.

[0132] As described above, in forming the composite coating, from the viewpoint of adhesion between the base material (or the underlayer, when it is present) and the composite coating, it is preferable to apply silver strike plating to the base material (underlayer) and then form the composite coating. After an entire surface layer of the base material is subjected to silver strike plating, the composite coating is formed on a part of the silver strike plated layer. The above is a step of forming the composite coating, and in this step, the silver coating is also formed at the same time.

[0133] Regarding the formation of the composite coating, the composite coating can be formed on a part of the silver coating without use of the mask by a technique using a silver plating solution, and by immersing a part of the silver strike plated base material (the portion that will become the terminal mating portion) in the silver plating solution. Since the silver plating solution undulates somewhat during plating, the boundary between the silver coating and the composite coating may not be a straight line when viewed from above, but this is not a problem as long as the terminal is designed to have a spacer portion with a dimension such as encompassing the boundary.

[0134] When the pre-coating formation method is adopted, the base material (typically having a flat plate shape) on which the silver coating and the composite coating are formed as described above, is processed into the shape of a terminal. Thus the terminal of the present invention is obtained. The obtained terminal has a configuration in which the silver coating composed of silver is formed on an entire surface layer of the base material, and the composite coating is formed on a part of the silver coating.

EXAMPLES

[0135] Hereinafter, examples of the present invention will be described in detail.

Example 1 Preparation of Carbon ParticlesOxidation Treatment

[0136] 80 g of scaly graphite particles (PAG-3000 manufactured by Nippon Graphite Industries Co., Ltd.) having an average particle size of 5 m as carbon particles were added to 1.4 L of pure water, and the mixture was heated to 50 C. while stirring. The average particle size is a particle size of 50% of the cumulative volumetric value, measured using a laser diffraction/scattering particle size distribution measuring device (MT3300 (LOW-WET MT3000II Mode) manufactured by Microtrack Bell Co., Ltd.). Next, 0.6 L of a 0.1 mol/L aqueous potassium persulfate solution was slowly dropped into this mixture as an oxidizing agent, and the mixture was then stirred for 2 hours to perform an oxidation treatment. Thereafter, the mixture was filtered using filter paper, and the obtained solid matter was cleaned with water.

[0137] A plate material composed of a CuNiSnP alloy (a copper alloy plate material containing 1.0 mass % of Ni, 0.9 mass % of Sn, 0.05 mass % of P, with the remainder being Cu and inevitable impurities) (NB-109EH manufactured by Dowa Metaltech Co., Ltd.) measuring 5.0 cm in length, 5.0 cm in width, and 0.2 mm in thickness was prepared. This plate material was used as the base material, and with this base material used as the cathode and an iridium oxide mesh electrode plate (a titanium mesh material coated with iridium oxide) used as the anode, electroplating (silver strike plating) was performed at a current density of 5 A/dm.sup.2 for 20 seconds in a sulfonic acid-based silver strike plating solution containing methanesulfonic acid as a complexing agent at 25 C. (Dainsilver GPE-ST manufactured by Daiwa Kasei Co., Ltd., silver concentration 3 g/L, methanesulfonic acid concentration 42 g/L). Silver strike plating was applied to an entire surface layer of the base material.

[0138] The carbon particles (graphite particles) that have been subjected to the above-described oxidation treatment were added to a sulfonic acid-based silver plating solution containing methanesulfonic acid as a complexing agent and having a silver concentration of 30 g/L and a methanesulfonic acid concentration of 60 g/L (Dainsilver GPE-HB (containing compound A corresponding to general formula (I) at a concentration of 4.2 g/L, with a solvent being mainly water) manufactured by Daiwa Kasei Co., Ltd.), to prepare a carbon particle-containing sulfonic acid-based silver plating solution containing carbon particles at a concentration of 50 g/L, silver at a concentration of 30 g/L, and methanesulfonic acid at a concentration of 60 g/L.

[0139] Next, with the above silver strike plated base material as the cathode and the silver electrode plate as the anode, the silver strike plated base material, 2.5 cm in length and 5.0 cm in width, was immersed in the sulfonic acid-based silver plating solution containing carbon particles, and while stirring with a stirrer at 400 rpm, electroplating was performed for 120 seconds at a temperature of 25 C. and a current density of 3 A/dm.sup.2, to obtain a composite material in which a composite coating containing carbon particles in a silver layer (AgC plated coating) was formed on the silver strike plated layer of the base material. The composite coating was formed on half of the surface of the silver strike plated layer of the base material (an area measuring 2.5 cm in length and 5.0 cm in width). In the AgC plating, the portion of the silver strike plated base material that was not immersed in the plating solution was not masked.

[0140] With the AgC plated side regarded as the terminal mating portion and the non-AgC plated side where the silver strike plated layer was exposed regarded as the soldering portion, the composite material obtained in example 1 was evaluated as follows

[0141] The thickness of a circular area with a diameter of 0.2 mm at the center of the exposed portion of the silver strike plated layer of the composite material (a surface of 2.5 cm5.0 cm) was measured using a fluorescent X-ray thickness meter (FT110A manufactured by Hitachi High-Tech Science Co. Ltd.) and as a result, the thickness was 0.03 m.

[0142] The thickness of the circular area with a diameter of 0.2 mm at the center of a 2.5 cm5.0 cm surface on the soldering portion side of the composite material was measured using a fluorescent X-ray thickness meter (FT110A, manufactured by Hitachi High-Tech Science Co. Ltd.). The thickness thus obtained was the sum of the thicknesses of the composite coating and the silver strike plated layer, and the thickness of the composite coating was obtained by subtracting the thickness of the silver strike plated layer from this sum. As a result, the thickness of the composite coating was 2 m. It is difficult to detect C atoms (of carbon particles) by a fluorescent X-ray thickness meter, and therefore the thickness is obtained by detecting Ag atoms, and in the present invention, the thickness thus obtained is regarded as the sum of the thickness of the composite coating and the silver strike plated layer.

[0143] The surface of the composite coating of the obtained composite material was subjected to ultrasonic cleaning treatment at 28 kHz for 4 minutes using an ultrasonic cleaner (VS-100III manufactured by AS ONE, output 100 W, tank dimensions: 140 mm in length240 mm in width100 mm in depth, used liquid was pure water, water temperature was 20 C.).

[0144] The carbon area percentage on the surface of the composite coating after the ultrasonic cleaning treatment was measured as follows.

[0145] The surface of the composite coating was observed using a tabletop microscope (TM4000 Plus manufactured by Hitachi High-Tech Co., Ltd.) at an accelerating voltage of 5 kV and a magnification of 1000 times, and a backscattered electron composition (COMPO) image (one field of view) was binarized using GIMP 2.10.10 (image analysis software), and the area percentage of carbon particles on the surface of the composite coating was calculated. Specifically, when a highest brightness is 255 and a lowest brightness is 0 in all pixels (8801270=1,117,600 pixels), a gradation is binarized such that pixels with a brightness of 127 or less are black and pixels with a brightness of more than 127 are white. Then, the image is separated into a silver portion (white portion) and a carbon particle portion (black portion), and the ratio Q/P of the number of pixels Q in the carbon particle portion with respect to the number of pixels P in an entire image was calculated as the carbon area percentage (%) on the surface. As a result, the area percentage of the carbon particles was 20%.

[0146] A flat test piece measuring 2.0 cm in width3.0 cm in length was cut out from the terminal mating portion of the composite material obtained in the above example 1.

[0147] On the other hand, a plurality of test pieces measuring 1.0 cm in width4.0 cm in length were cut out from the terminal mating portions of the composite material obtained in the above example 1, and an indentation treatment (extrusion into a hemispherical shape) with an inner diameter of 1.0 mm was performed to each of the test pieces to obtain indented test pieces (indenters). In this manner, in example 1, both flat test pieces and indented test pieces were prepared from (the terminal mating portion) of the composite material of example 1. The same applies to the subsequent examples and comparative examples (for example, in example 2, both flat test pieces and indented test pieces were prepared from the composite material of example 2).

[0148] A wear test was performed using a sliding wear tester (CRS-G2050-DWA, manufactured by Yamazaki Seiki Laboratory Co., Ltd.) by pressing the indented test piece against the flat test piece with a constant load (2N) so that the convex portion of the indented test piece touched the flat test piece, and in this state, a reciprocating sliding motion (sliding distance 50 m (100 m for one round trip) was continued, sliding speed was 3 mm/s), and a wear state of the indented test piece and the flat test piece was checked, to evaluate the micro-friction wear properties. The result was as follows: after 5,000 reciprocating sliding motions, the center of the sliding marks on the indented test piece and the flat test piece were observed at a magnification of 200 times using a microscope (VHX-1000 manufactured by Keyence Co., Ltd.), and it was confirmed that the (brown) base material was not exposed from either of the sliding marks, and it was found that the terminal mating portion side of the composite material of example 1 had excellent micro-friction wear properties.

[0149] As in the case of evaluating the micro-friction wear properties, the terminal mating portion of the composite material obtained in example 1 was used to fabricate a flat test piece and an indented test piece.

[0150] Then, using a sliding wear tester (CRS-G2050-DWA, manufactured by Yamazaki Seiki Laboratory Co., Ltd.), the indented test piece was pressed against the flat test piece with a constant load (2N) so that the convex portion of the indented test piece touches the surface of the composite coating of the flat test piece, and in this state, the indented test piece was slid at a sliding speed of 0.4 mm/see, to measure the sliding load from the start of the sliding until a sliding distance of 5 mm was reached. Then, sliding load data for a sliding distance of 2 mm to 3 mm was averaged to determine the coefficient of friction (average sliding load F/5N). As a result, the coefficient of friction of the terminal mating portion was 0.20.

[0151] A flat test piece measuring 1.0 cm in width2.5 cm in length was cut out from the soldering portion of the composite material obtained in the above example 1. After being kept (aged) in the atmosphere at 155 C. for 16 hours, evaluation was performed under test conditions shown below. As a result, the wetted area percentage was 85%, and it was found that the soldering portion of the composite material of example 1 had excellent solderability.

[Test Conditions]

[0152] Solder: Sn-3Ag-0.5Cu [0153] Solder bath temperature: 250 C. [0154] Flux: Inactive rosin flux (test piece was immersed in the flux) [0155] Speed at which test piece was immersed in solder: 25 mm/s [0156] Depth at which test piece was immersed in solder: 4 mm [0157] Time at which test piece was immersed in solder: 5 s [0158] Method of evaluation: The percentage of the immersed area that was wetted with solder was obtained.

Example 2

[0159] With the same material as in example 1 used as the cathode and a Ni electrode plate used as the anode, in a nickel plating bath (aqueous solution) composed of nickel sulfamate at a concentration of 342 g/L (Ni concentration of 80 g/L) and boric acid at a concentration of 45 g/L, electroplating (Ni plating) was performed for 40 seconds while stirring at a liquid temperature of 55 C. and a current density of 4 A/dm.sup.2, to form a Ni coating (Ni underlayer) having a thickness of 0.2 m on the base material. The thickness of the underlayer was measured in the same manner as the thickness of the composite coating.

[0160] A composite material was fabricated in the same manner as in example 1, except that silver strike plating was applied to the base material having a Ni undercoat formed thereon.

[0161] For the obtained composite material, the thickness of the composite coating, the thickness of the silver strike plated layer, the carbon area percentage and the coefficient of friction on the surface of the composite coating after ultrasonic cleaning treatment were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1.

Example 3

[0162] A composite material was fabricated in the same manner as in example 2, except that electroplating (silver strike plating) was performed to the base material having the Ni undercoat at a current density of 5 A/dm.sup.2 for 150 seconds. For the obtained composite material, the thickness of the composite coating, the thickness of the silver strike plated layer, the carbon area percentage on the surface of the composite coating and the coefficient of friction after ultrasonic cleaning treatment were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1.

Example 4

[0163] A composite material was fabricated in the same manner as in example 2, except that the base material having the Ni undercoat formed thereon was subjected to electroplating (silver strike plating) at a current density of 5 A/dm.sup.2 for 375 seconds. For the obtained composite material, the thickness of the composite coating, the thickness of the silver strike plated layer, the carbon area percentage on the surface of the composite coating and the coefficient of friction after ultrasonic cleaning treatment were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1.

Example 5

[0164] 60 g of the oxidized carbon particles used in example 1 was added to 0.6 L of pure water, and then 100 g of an aqueous solution of poly(diallyldimethylammonium chloride) (weight average molecular weight: 1,600, number average molecular weight: 1,500) (Unisense FPA100L manufactured by Senka Co. Ltd, poly (diallyldimethylammonium chloride) concentration of 25 to 35 mass %) was added, and the mixture was stirred at a liquid temperature of 25 C. for 24 hours, thereby applying a surface treatment to the carbon particles. Thereafter, a solid matter was filtered through a filter paper, and the solid matter thus obtained was cleaned with water until the electrical conductivity of the filtrate reached 10 S/cm. An average molecular weight was measured by gel permeation chromatography (GPC) under the following conditions. [0165] Eluent: Water (containing sodium nitrate at a concentration of 0.1 mol/L and acetic acid at a concentration of 0.5 mol/L) [0166] Standard substance: Mixture of polyethylene oxide (standard substance for molecular weights of 10,000 or more) and polyethylene glycol (standard substance for molecular weights of less than 10,000) [0167] Sample concentration: 0.2 w/v % [0168] Injection volume: 100 L [0169] Flow rate: 1.0 mL/min [0170] Column: Shodex OHpak SB-806M HQ2 (manufactured by Showa Denko Co. Ltd.) [0171] Column temperature: 40 C. [0172] Pump: LC-10ADvp (manufactured by Shimadzu Co. Ltd.) [0173] Detector: Shodex RI-71 (manufactured by Showa Denko Co. Ltd.)

[0174] A composite material was fabricated in the same manner as in example 3, except that carbon particles (graphite particles) that had been subjected to surface treatment with the above-described polymer were used as the carbon particles and the plating time for AgC plating was changed to 60 seconds. For the obtained composite material, the thickness of the composite coating, the thickness of the silver strike plated layer, the carbon area percentage and the coefficient of friction on the surface of the composite coating after ultrasonic cleaning treatment were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1.

Comparative Example 1 Silver Strike Plating

[0175] Silver strike plating was performed in the same manner as in example 3, except that silver strike plating was applied to half of the surface layer (a region of 2.5 cm in length and 5.0 cm in width) of a plate material composed of a CuNiSnP alloy, measuring 5.0 cm in length, 5.0 cm in width, and 0.2 mm in thickness (a copper alloy plate material containing 1.0 mass % of Ni, 0.9 mass % of Sn, 0.05 mass % of P, with the remainder being Cu and inevitable impurities) (NB-109EH manufactured by Dowa Metaltech Co., Ltd.).

[0176] With the above silver strike-plated base material as the cathode and a silver electrode plate as the anode, a composite material was fabricated in the same manner as in example 1, except that the silver strike-plated portion of the base material, measuring 2.5 cm in length and 5.0 cm in width, was immersed in a sulfonic acid-based silver plating solution containing carbon particles. For the obtained composite material, the thickness of the composite coating, the thickness of the silver strike plated layer, the carbon area percentage and the coefficient of friction on the surface of the composite coating after ultrasonic cleaning treatment were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1. The thickness of the silver strike plated layer was measured before forming the composite coating, and solderability was evaluated on the unplated portion of the base material.

Comparative Example 2

[0177] In the same manner as in example 3, Ni underlayer was formed on the base material, and then silver strike plating was applied thereto. With this silver strike-plated base material used as the cathode and the silver electrode plate used as the anode, the silver strike-plated base material measuring 5.0 cm in length and 5.0 cm in width (entire surface of the base material) was immersed in the same sulfonic acid-based silver plating solution containing carbon particles as used in example 1, and electroplating was performed thereto for 120 seconds at a temperature of 25 C. and a current density of 3 A/dm.sup.2 while stirring with a stirrer at 400 rpm, to obtain a composite material in which a composite coating containing carbon particles in a silver layer was formed over an entire surface layer of the base material (the silver strike plated layer).

[0178] For the obtained composite material, the thickness of the composite coating, the thickness of the silver strike plated layer, the carbon area percentage and the coefficient of friction on the surface of the composite coating after ultrasonic cleaning treatment were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1. The thickness of the silver strike plated layer was measured before forming the composite coating. Further, to evaluate the solderability, a flat test piece measuring 1.0 cm in width2.5 cm in length was cut out from the composite material of comparative example 1 (the outermost surface of the test piece other than the cut end was composed of a composite coating), and this flat test piece was used for the evaluation.

Comparative Example 3 Sn Plating

[0179] Sn plating solution was prepared, which is composed of an aqueous solution containing 70 g/L of stannous sulfate (SnSO.sub.4) (Sn concentration of 39 g/L), 75 g/L of sulfuric acid (H.sub.2SO.sub.4), 30 g/L of cresol sulfonic acid as a leveling agent, and 2 g/L of polyoxyethylene stearylamine as a surfactant.

[0180] With the same base material as in example 1 used as the cathode and the Sn electrode plate used as the anode, the base material measuring 5.0 cm in length and 5.0 cm in width (entire surface of the base material) was immersed in the above Sn plating solution, and electroplating was performed thereto for 55 seconds at a temperature of 25 C. and a current density of 4 A/dm.sup.2 while stirring with a stirrer at 400 rpm, to obtain a plated material having a tin metal coating (Sn plated coating) formed on the base material. The metal coating was formed on the entire surface layer (an area of 5.0 cm in length and 5.0 cm in width) of the base material.

[0181] The obtained Sn-plated material was subjected to a reflow treatment (Sn melting treatment). In this reflow treatment, a near-infrared heater (HYW-8N manufactured by Hibeck Co., Ltd., rated voltage 100V, rated power 560 W) was used, and a current value was set to 10.8 A using a power supply controller (HYW-20CCR-aN manufactured by Hibeck Co., Ltd.), and the Sn-plated material was heated (to approximately 250 C.) for 11 seconds in the air atmosphere to melt the surface of the Sn-plated layer. Immediately after this process, the Sn-plated material was immersed in a water tank at 20 C. to be cooled.

[0182] For the obtained reflow Sn-plated material, the thickness and the coefficient of friction of the Sn-plated film were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1.

Comparative Example 4 Ag Plating

[0183] The base material was subjected to silver strike plating in the same manner as in example 1, except that the plating time was changed to 150 seconds.

[0184] A sulfonic acid-based silver plating solution (Dainsilver GPE-HB, manufactured by Daiwa Kasei Co., Ltd.) similar to that used in example 1 was prepared. With the above silver strike plated material as the cathode and the silver electrode plate as the anode, the silver strike-plated base material measuring 5.0 cm in length and 5.0 cm in width (entire surface of the base material) was immersed in the sulfonic acid-based silver plating solution, and subjected to electroplating for 120 seconds at a temperature of 25 C. and a current density of 3 A/dm.sup.2 while stirring with a stirrer at 400 rpm, to obtain a plated material having an Ag-plated film formed on the base material. The Ag-plated film was formed on an entire surface layer (an area of 5.0 cm in length and 5.0 cm in width) of the base material.

[0185] For the obtained Ag-plated material, the thickness and the coefficient of friction of the silver coating were obtained and micro-friction wear properties and solderability were evaluated in the same manner as in example 1.

[0186] Manufacturing conditions of the composite material, Sn-plated material, and Ag-plated material of examples 1 to 5 and comparative examples 1 to 4 are summarized in table 1 below, and the various evaluation results are summarized in table 2 below.

TABLE-US-00001 TABLE 1 Example Example Example Example Example Com. Com. Com. Com. 1 2 3 4 5 Ex. 1** Ex. 2 Ex. 3 Ex. 4 Under- Main Nickel 80 80 80 80 80 layer components (g/L) of plating Complexing 45 45 45 45 45 solution Agent (Boric acid (g/L) Current density (A/dm.sup.2) 4 4 4 4 4 Plating temperature ( C.) 55 55 55 55 55 Plating time (second) 40 40 40 40 40 Strike Main Silver ion 3 3 3 3 3 3 3 3 plating components (g/L) of plating Methane- 42 42 42 42 42 42 42 42 solution sulfonic acid (g/L) Current density (A/dm.sup.2) 5 5 5 5 5 5 5 5 Plating temperature ( C.) 25 25 25 25 25 25 25 25 Plating time (second) 20 20 150 375 150 150 150 150 Ag based Main Silver 30 30 30 30 30 30 30 30 plating/ components ion (g/L) Sn plating of plating Tin 39 solution ion (g/L) Compound A Present Present Present Present Present Present Present Absent Present Methane- 60 60 60 60 60 60 60 60 sulfonic acid (g/L) Other additive Sulfuric acid Cresol sulfonic acid Polyoxy- ethylene stearylamine Carbon particle 50 50 50 50 50 50 50 concentration (g/L) Polymer Without Without Without Without With Without Without treatment treatment treatment treatment treatment treatment treatment treatment for carbon particles Current density (A/dm.sup.2) 3 3 3 3 3 3 3 4 3 Plating temperature ( C.) 25 25 25 25 25 25 25 25 25 Plating time (second) 120 120 120 120 60 120 120 55 120 Plating area Half of Half of Half of Half of Half of Half of Entire Entire Entire the surface the surface the surface the surface the surface the surface surface surface surface Reflow treatment Without Without Without Without Without Without Without With Without treat- treat- treat- treat- treat- treat- treat- treat- treat- ment ment ment ment ment ment ment ment ment *Com. Ex = Comparative Example **In comparative 1, silver strike plating was applied to half of the surface of the base material.

TABLE-US-00002 TABLE 2 Structure of the coating on the base material Structure of the coating of the Structure of the coating of the soldering portion terminal mating portion (base material side .fwdarw. surface layer side) (base material side .fwdarw. surface layer side) Thick- Thick- ness of ness of Thick- composite Thick- composite Soldering Thick- ness coating Thick- Thick- Thick- ness coating Thick- Thick- evaluation ness of Ag Area ness ness ness of Ag Area ness ness Micro- (Solder of Ni strike percentage of Sn- of Ag- of Ni strike percentage of Sn- of Ag- Coeffi- friction welded Example under- plated of sur- plated plated under- plated of sur- plated plated cient of wear area per- No. layer layer face C layer layer layer layer face C layer layer friction properties centage) Example 0.03 m 0.03 m 2 m 0.20 No exposed 85% 1 20% base material after 5,000 reciprocating sliding operations Example 0.2 m 0.03 m 0.2 m 0.03 m 2 m 0.20 No exposed 100% 2 20% base material after 5,000 reciprocating sliding operations Example 0.2 m 0.20 m 0.2 m 0.20 m 2 m 0.20 No exposed 100% 3 20% base material after 5,000 reciprocating sliding operations Example 0.2 m 0.52 m 0.2 m 0.52 m 2 m 0.20 No exposed 100% 4 20% base material after 5,000 reciprocating sliding operations Example 0.2 m 0.20 m 0.2 m 0.20 m 0.6 m 0.21 No exposed 100% 5 11% base material after 5,000 reciprocating sliding operations Com. 0.2 m 0.20 m 2 m 0.20 No exposed 35% Ex. 1 20% base material after 5,000 reciprocating sliding operations Com. 0.2 m 0.20 m 2 m 0.2 m 0.20 m 2 m 0.20 No exposed 3% Ex. 2 20% 20% base material after 5,000 reciprocating sliding operations Com. 1 m 1 m 0.56 Base material 100% Ex. 3 was exposed after 40 reciprocating sliding operations Com. 0.20 m 2 m 0.20 m 2 m 1.50 Base material 100% Ex. 4 was exposed after 4000 reciprocating sliding operations *Com. Ex = Comparative Example

DESCRIPTIONS OF SIGNS AND NUMERALS

[0187] 10 Composite material [0188] 12 Base material [0189] 14 Metal coating [0190] 16 Composite coating [0191] 18 Exposed portion of metal coating [0192] 20 Exposed portion of composite coating [0193] 22 Area extending from a part of the exposed metal coating portion 18 to a part of the [0194] exposed composite coating portion 20 [0195] 30 Terminal mating portion [0196] 32 Soldering portion [0197] 34 Spacer portion [0198] 36 Base material [0199] 38 Metal coating [0200] 40 Composite coating [0201] 42 Exposed portion of metal coating [0202] 44 Exposed portion of composite coating [0203] 50 Casing member [0204] 60 Terminal [0205] 70 Female terminal [0206] 72 Container [0207] 74 Fixing portion [0208] 76 Casing member

COMPOSITE MATERIAL, TERMINAL AND METHOD FOR MANUFACTURING TERMINAL

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Cpc classification

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Abstract

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