JP2012057212A - Composite plated material, and electric component and electronic component using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite plated material which has excellent conductivity, strength and wear resistance, exhibits a contact resistance that hardly increases, and thereby has good contact reliability.SOLUTION: In the composite plated material, at least one first-plating layer composed of copper, nickel, cobalt, iron or an alloy containing two or more elements selected from these elements is formed on a conductive base material, and a surface plated layer composed of tin, silver or an alloy containing these elements is formed on the first-plating layer. The surface plated layer contains fine particles, including carbon as a main component, in an amount of 5-10 vol.%. In the surface plated layer, the distribution of the fine particles is increased toward the outer surface of the surface plated layer, and the number of the particles of 50-80 vol.% of the total volume of the fine particles contained in the whole surface plated layer is included in the range to the half of the thickness from the outer surface of the surface plated layer.

Description

  The present invention relates to a composite plating material and an electric / electronic component using the composite plating material. More specifically, it is excellent in slidability and wear resistance. For example, a composite plating material suitable as a material for fitting type terminals and connectors, sliding type and rotary type contacts and switches, and a fitting type using the same. It relates to electrical / electronic components such as terminals, connectors, contacts, and switches.

  A material in which a plating layer made of tin (Sn) or Sn alloy is provided on a conductive base material made of copper (Cu) or Cu alloy, etc., has excellent conductivity and strength of the base material, and Sn or Sn alloy. It is known as a high-performance conductor that combines good electrical contact characteristics and is widely used for various terminals and contacts.

  As such a material, a material produced by applying a plating of Sn or Sn alloy as a surface plating layer directly on a base material or after applying a base plating such as Cu or nickel (Ni) is used. Yes. This underlayer is provided in order to prevent the base material component (alloy component such as Cu or zinc (Zn)) from diffusing into the surface Sn or Sn alloy. When the underlayer is made of Ni or a Ni alloy, it has an effect of improving the slidability by increasing the hardness of the plating film on the substrate, which is suitable as the undercoat.

  In recent years, as represented by automotive applications, the amount of electricity applied to electrical and electronic components has increased and the use of high loads has increased. Sex is required.

  However, the Sn plating material is soft and easily deformed, and there is a problem that the friction coefficient at the time of sliding the contact becomes high, and the thickness of the Sn plating film decreases due to wear due to sliding and rotation. When the thickness of the Sn plating layer decreases and eventually disappears, a base layer such as Ni plating or a substrate such as Cu or Cu alloy is exposed on the surface. In such a state, an oxide of the base material or the base material is formed by further sliding or rotation, and as a result, the contact resistance increases and the contact reliability with the counterpart material is lost.

  A solution to such a problem includes increasing the time until the plating layer disappears by increasing the thickness of the Sn plating layer. However, such a plating material has a problem that a decrease in productivity and an increase in cost are unavoidable.

  As another method, a reflow treatment is performed after Sn plating to obtain a Sn reflow material. The Sn reflow material reduces the friction and wear by reducing the thickness of the soft Sn plating layer and forming a hard Sn compound layer between the base plating layer and the Sn plating layer by reflow treatment. However, the effect of reducing the friction and wear due to the Sn reflow process alone is relatively small, and improvement in contact reliability cannot be expected so much.

  In addition, applying conductive grease on the Sn plating layer is also effective in suppressing wear during sliding. However, although the contact resistance is low and stable in the stationary state, there is a problem that the contact resistance is likely to increase due to deterioration or solidification of the grease during sliding or in a high temperature environment, resulting in poor contact reliability.

  In addition to this, as another plating material that meets the above-described demand, Sn alloy plating in which other metal elements are added to Sn can be cited. Sn alloy plating is often used in sliding applications because the hardness of the plating film is increased and the wear resistance is improved as compared with Sn plating. However, in an alloy containing an element other than Sn, the conductivity is lowered. Therefore, it is not preferable from the viewpoint of contact reliability with respect to an increase in the amount of energization.

  In order to improve the sliding characteristics of Sn or Sn alloy plating, a method of dispersing wear-resistant or lubricating solid particles in the Sn plating layer is disclosed (for example, see Patent Documents 1 to 3). However, in the case of the Sn plating layer formed by this method, when solid particles are exposed on the surface due to wear of Sn, there is a problem that the contact resistance is greatly increased due to the low conductivity of the solid particles.

  It has also been proposed to form a composite plating layer in which graphite is dispersed in an Sn or Sn alloy plating layer on a conductor material to obtain a conductive film having excellent sliding characteristics (see, for example, Patent Documents 4 and 5). ). However, in the case of the Sn plating layer formed by this method, the shape of the graphite is anisotropic, and the dispersed state in the plating layer is irregularly oriented. For this reason, when the graphite is exposed on the surface layer with the wear of Sn, the conductivity of the graphite itself is comparable to that of metal, but the contact resistance increases due to the decrease in the contact area at the contact. In addition, in the case of Sn plating formed by this method, since the particle size of graphite is large, it is impossible to control the distribution of graphite in the plating layer or to apply to thin plating.

  Thus, in the case of the conventional plating material which formed the plating layer which consists of Sn or a Sn alloy on the surface, there existed a problem that it was difficult to make the wear resistance and electroconductivity compatible.

  A material provided with a plating layer made of silver (Ag) or an Ag alloy on a conductive base material made of copper (Cu), Cu alloy, stainless steel (SUS), iron alloy or the like is also known as a high-performance conductor. Widely used for various contacts and switches.

  In the case of an Ag plating material, there are the same problems as the Sn plating material, and the above measures are taken (for example, Patent Documents 6 to 11), but it is still difficult to achieve both wear resistance and conductivity. It is.

JP 54-45634 A Japanese Patent Laid-Open No. 53-11131 JP 63-145819 A Japanese Patent Laid-Open No. 61-227196 JP 2006-265642 A JP-A-61-101919 JP 2000-508379 JP-A-4-126314 Japanese Patent Laid-Open No. 9-326227 JP-A-11-149840 JP 2006-37225 A

  An object of this invention is to provide the composite plating material which is excellent in electroconductivity, intensity | strength, and abrasion resistance, and also has good contact reliability which a contact resistance does not raise easily. Furthermore, an object of the present invention is to provide an electric / electronic component, a fitting type terminal / connector, a sliding type or rotating type contact, and a switch using the composite plating material.

In order to achieve the above-described goal, in the present invention, the above-described goal is achieved by the following plating materials, electrical / electronic components, fitting-type terminals / connectors, sliding-type or rotary-type contacts or switches. .
That is, the present invention provides the following means.
(1) At least one base plating layer made of copper, nickel, cobalt, iron or an alloy containing two or more of these elements is formed on the conductive substrate, and tin, silver, or these A composite plating material in which a surface plating layer made of an alloy containing an element is formed,
The surface plating layer contains 5 to 10% by volume of fine particles containing carbon as a main component, and the distribution of the fine particles increases toward the outer surface of the surface plating layer, and is included in the entire surface plating layer. What is more than 50 volume% and not more than 80 volume% with respect to the total volume of microparticles | fine-particles is contained to the half of the thickness from the outer surface of the said surface plating layer, The composite plating material characterized by the above-mentioned.
(2) The surface plating layer has a single-layer structure including fine particles mainly composed of carbon in a metal plating layer made of tin, silver or an alloy containing these elements. Composite plating material.
(3) The surface plating layer is formed by alternately forming a metal plating layer made of tin, silver or an alloy containing these elements and a fine particle layer made of fine particles mainly composed of carbon. The composite plating material as described in (1), which has a multilayer structure.
(4) The composite plating material according to any one of (1) to (3), wherein the fine particles have an average particle diameter of 20 to 400 nm and are spherical.
(5) The thickness of the base plating layer is 0.05 to 2.0 μm, and the thickness of the surface plating layer is 0.5 to 5 μm. The composite plating material according to any one of the above.
(6) An electrical / electronic component formed using the composite plating material according to any one of (1) to (5).
(7) A fitting type terminal / connector, sliding type or rotary type contact member or switch formed using the composite plating material according to any one of (1) to (5).

In the composite plating material of the present invention, the wear resistance is improved by dispersing fine particles mainly composed of graphite in the surface layer portion of the surface plating layer made of Sn, Ag or an alloy containing these elements. Reliability is maintained well.
Since it has such characteristics, the composite plating material of the present invention is suitable as a material for fitting terminals / connectors of electric / electronic parts, sliding and rotating contacts, and switches, for example.

It is sectional drawing which shows typically preferable one Embodiment of the plating material of this invention. It is sectional drawing which shows typically other preferable one Embodiment of the plating material of this invention. It is sectional drawing which shows typically the preferable dispersion structure of the microparticles | fine-particles in the surface plating layer of embodiment shown in FIG. It is sectional drawing which shows typically the preferable dispersion structure of the microparticles | fine-particles in the surface plating layer of embodiment shown in FIG.

  In the composite plating material of the present invention, a surface plating layer made of Sn, Ag, or an alloy containing these elements is formed on a conductive substrate, containing fine particles mainly composed of carbon, and on the outer surface thereof. The closer the particles are, the larger the distribution (presence rate) of the fine particles. The state of the presence of the fine particles is not particularly limited. Even if the fine particles are exposed to the surface layer portion, they may exist in a predetermined distribution in the whole layer or inside, and even if particles exist at the interface between the underlying plating layer and the surface plating layer. Good. In the present invention, the term “includes” is meant to include such various forms of existence.

  In a preferred embodiment of the composite plating material of the present invention, as shown in FIG. 1, at least one base plating layer 2 is formed on a conductive substrate 1, and a surface plating layer is further formed thereon. The surface plating layer has a single layer structure in which fine particles 4 mainly composed of carbon are dispersed in a metal plating layer 31 made of Sn, Ag, or an alloy containing these elements (hereinafter referred to as a single layer plating layer 3). .) In this embodiment, an outer surface means the surface where the single-layer plating layer 3 is exposed to the outside in the composite plating material, as indicated by reference numeral 32 in FIG. Moreover, the thickness of the single-layer plating layer 3 as a surface plating layer is the thickness from the outer surface 32 to the interface 33 with the base plating layer 2.

As another preferred embodiment of the composite plating material of the present invention, as shown in FIG. 2, a metal plating layer 51 made of Sn, Ag or an alloy containing these elements and carbon are formed on the base plating layer 2 and carbon. A surface plating layer having a multilayer structure (hereinafter referred to as multilayer plating layer 5) is formed by alternately forming fine particle layers 52 made of fine particles as a main component.
The multilayer plating layer 5 in the present embodiment is a surface plating layer that is the entire multilayer structure that does not include the base plating layer 2. The outer surface means the outermost surface that is located on the outermost side of the multilayer structure and exposed outward in the composite plating material, as indicated by reference numeral 53 in FIG. Moreover, the thickness of the multilayer plating layer 5 which is a surface plating layer is the thickness from the outer surface 53 to the interface 54 with the base plating layer 2.
When the surface plating layer is the multilayer plating layer 5, the metal part and the fine particle part of the surface plating layer can be individually formed as compared with the case where the surface plating layer is the single-layer plating layer 3. The distribution can be easily controlled. In the multilayer plating layer 5, the metal plating layer 51 has a structure of a single plating metal phase, and the fine particle layer 52 has a structure of a composite phase in which fine particles are contained in the plating metal phase. After the metal plating layer 51 and the fine particle layer 52 form the multilayer plating layer 5, the plating metal phases of the metal plating layer 51 and the fine particle layer 52 are continuously bonded, and a clear boundary is not seen. The multilayer plating layer 5 preferably includes two or three metal plating layers 51. By setting it as this number of layers, the thickness of the multilayer plating layer 5 is not increased more than necessary, and it is also preferable from the viewpoint of productivity.

3 is a cross-sectional view schematically showing a composite plating layer having a high dispersion concentration of carbon fine particles on the outer surface of the single-layer plating layer 3, and FIG. 4 shows a high dispersion concentration of carbon fine particles on the outer surface of the multilayer plating layer 5. It is sectional drawing which shows a composite plating layer typically. 3 and 4, the center line c in the thickness direction of each surface plating layer is indicated by a one-dot chain line.
In the present invention, both the single-layer plating layer 3 and the multilayer plating layer 5 have a volume amount of more than 50% by volume and 80% by volume or less with respect to the total volume of fine particles contained in the entire surface plating layer. It is desirable that the plating layer is contained within half of the thickness from the outer surface (hereinafter, this ratio is also referred to as surface side content), and the rest is contained on the substrate side of the plating layer. That is, in the single-layer plating layer 3 shown in FIG. 3, the volume of fine particles in the upper part 3a on the outer surface 32 side from the center line c is larger than the volume of fine particles in the lower part 3b. Moreover, in the multilayer plating layer 5 shown in FIG. 4, the sum of the volume of fine particles of each fine particle layer 52 in the upper part 5a on the outer surface 53 side from the center line c is larger than the sum of the volume of fine particles in the lower part 5b. It is arranged. By inclining the fine particle concentration in the plating layer, even if the plating layer wears by sliding and the fine particles in the sliding portion remain, an increase in the fine particle concentration in the sliding portion can be prevented. The lower limit of the surface side content is preferably 55% by volume or more, and more preferably 60% by volume or more. There is no restriction | limiting in particular as an upper limit, 80 volume% or less may be sufficient. When the above lower limit is exceeded (or more), the effect of improving the slidability and wear by fine particles is effectively obtained in the early stage of sliding, and when the upper limit is not reached, contact reliability, sliding And wear resistance are fully realized.

  The fine particle concentration and concentration gradient in the surface plating layer can be obtained by observing the cross section of the surface plating layer using an electron microscope, obtaining the average equivalent circle diameter of the particles, and calculating the volume therefrom. First, the number of fine particles observed in a unit area on the cross-sectional observation surface of the surface plating layer is measured, and the number of fine particles contained in the unit volume of the surface plating layer is calculated therefrom. Here, the total volume of the fine particles contained in the surface plating layer of the unit volume is obtained using the fine particle volume having the average equivalent circle diameter, and the volume% is calculated from the result.

  The material of the conductive substrate 1 is not particularly limited. For example, in consideration of the use as a connector, depending on the required mechanical strength, heat resistance, and conductivity, for example, pure copper; phosphor bronze, brass Copper alloy such as iron white, beryllium copper, corson alloy; pure iron; iron alloy such as stainless steel; various Ni alloys; composite materials such as Cu coating materials and Ni coating materials may be appropriately selected. . Moreover, as a shape of an electroconductive base material, any shape of a strip and a wire may be sufficient.

  Of these materials, Cu or Cu alloys are preferred. In addition, even when the conductive substrate 1 is not a Cu-based material, it is expected to improve the adhesion and corrosion resistance of the plating film by applying the base plating containing copper, nickel, cobalt, iron, and the like to actual use. it can.

  Of the surface plating layer, the portion of the metal plating layer 51 of the multilayer plating layer 5 is obtained by forming Sn, Ag or an alloy containing these elements by electrolytic plating or electroless plating, and is used as an electrical contact as a plating material. Provided to ensure characteristics, corrosion resistance, and solderability. When the surface plating layer is an alloy, the wear resistance can be improved. Moreover, when a surface plating layer is Sn or the alloy containing Sn, it can be set as a reflow material by performing a reflow process after metal plating, and friction and wear can be reduced. The thickness of the surface plating layer is preferably 0.5 μm or more, and more preferably 1 to 5 μm from the viewpoint of life and productivity. When the surface plating layer is 0.5 μm or less, the contact resistance during heat treatment is remarkably increased, and the life of the composite plating material is shortened.

  Part of the fine particle layer 52 of the single-layer plating layer 3 and the multilayer plating layer 5 disperses fine particles mainly composed of carbon in an alloy plating bath containing Sn, Ag, or these elements, and deposits them simultaneously with these metals. Can be obtained. In this case, the fine particle layer 52 is formed by electrolytic plating or electroless plating. The fine particle layer can also be obtained by immersing a base material in a solution in which fine particles are dispersed and adsorbing the fine particles on the surface thereof.

  In order to cause the fine particles to co-deposit in the surface plating layer (single-layer plating layer 3 and multilayer plating layer 5), it is preferable that the fine particles are in a dispersed state in the plating solution. In this case, a surfactant may be used in order to improve the dispersibility of the fine particles in the plating solution. There is no restriction | limiting in particular in the kind of surfactant, For example, anionic, cationic, nonionic, and amphoteric surfactant can be used. When the surfactant treatment is not performed and the dispersibility in the liquid is poor, the fine particles may be aggregated and coarsened in the plating solution, and the fine particles may not be sufficiently taken up when the plating layer is formed.

  As the composite plating material having fine particles in the surface layer portion of the single layer plating layer 3 and the multilayer plating layer 5, the surface plating layer as shown in FIG. 1 and FIG. 2 is used as the composite plating layer, and the fine particle dispersion concentration is close to the outer surface. Is provided as a high composite plating layer.

In the case of a composite plating layer having a high dispersion concentration of fine particles near the outer surface of the single-layer plating layer 3 or the multilayer plating layer 5 as shown in FIGS. 3 and 4, the fine particles are removed every time the surface plating layer is worn. It is exposed to the surface, and the amount of wear during sliding can be reduced, so that the wear resistance can be maintained over almost the entire thickness of the single-layer plating layer 3 or the multilayer plating layer 5. The interface between the single-layer plating layer 3 or the multilayer plating layer 5 and the base plating layer 2 or the conductive substrate 1 is preferably excellent in plating adhesion and conductivity because it does not contain fine particles 4. In the structure in which the fine particles 4 are not arranged at the interface between the surface plating layer and the base plating layer 2 or the conductive substrate 1, Sn, Ag or their elements are used as an adhesion improving layer between the base plating layer 2 and the surface plating layer. It is formed by the method of forming the layer which consists of an alloy containing. Further, when the surface plating layer is the single-layer plating layer 3, this structure can be obtained by starting the plating from such a condition that fine particles are not co-deposited. In the case of the multilayer plating layer 5, the metal plating layer 51 may be formed first.
Such a plating material is, for example, a mixture of Sn, Ag or fine particles dispersed in an alloy plating bath containing these elements. By continuously changing the plating conditions such as current density, or by continuously using a plurality of plating tanks (baths) having different fine particle concentrations, plating layers having different dispersion concentrations of the fine particles 4 are formed. Obtained. In particular, in the multilayer plating layer 5, by arranging a plurality of plating layers having different dispersion concentrations of the fine particles 4 as the fine particle layer 52, an inclined arrangement of the fine particle dispersion concentration is possible.

In the case of a composite plating layer having a high dispersion concentration of fine particles near the outer surface of the single-layer plating layer 3 or the multilayer plating layer 5 as shown in FIGS. 3 and 4, the fine particles are removed every time the surface plating layer is worn. It is exposed to the surface, and the amount of wear during sliding can be reduced, so that the wear resistance can be maintained over almost the entire thickness of the single-layer plating layer 3 or the multilayer plating layer 5.
A single-layer plating layer 3 as shown in FIG. 3 is a single plating when a surface plating layer is applied to the conductive substrate 1 in an alloy plating bath containing Sn, Ag or these elements in which fine particles are dispersed, for example. It can be obtained by continuously changing plating conditions such as stirring speed and current density in the bath or by continuously using a plurality of plating baths having different concentrations of fine particles. In a single plating bath, plating is performed by continuously changing the plating conditions from the condition where fine particles are not co-deposited to the direction in which the amount of eutectoid gradually increases, or without dispersing fine particles in the first bath of multiple plating baths. By plating, fine particles are not included in the interface between the single-layer plating layer 3 and the base plating layer 2 or the conductive substrate 1, and the plating adhesion and conductivity are further improved.
Also, the multilayer plating layer 5 as shown in FIG. 4 can be obtained by adjusting the plating thicknesses of the metal plating layer 51 and the fine particle layer 52 or by arranging a plurality of plating layers having different dispersion concentrations as the fine particle layer 52. By forming the metal plating layer 51 first, fine particles are not included in the interface between the multilayer plating layer 5 and the base plating layer 2 or the conductive substrate 1, and the plating adhesion and conductivity are further improved.

The kind of the fine particles 4 is not particularly limited, and fine particles mainly composed of carbon such as carbon black, graphite, carbon nanotube, ketjen, coke, etc. can be used. Among these, it is more preferable to use carbon black fine particles. When a small amount of fine particles composed of components other than carbon are present in the fine particles, the content is preferably 10% by weight or less, particularly preferably 5% by weight or less, based on the total fine particles. If the fine particles of other components are increased, the target wear resistance and contact reliability cannot be obtained when a composite plating material is produced according to the present invention. The other components mentioned here mean hydrogen, oxygen, fluorine, sulfur, silicon and the like.

  The fine particles 4 are preferably spherical, and the particle diameter is preferably 20 to 400 nm. The particle size is an average particle size, and the particle size dispersed in the actual plating film may vary. When the particle diameter is 20 nm or less, the effect of improving the slidability and wear by fine particles cannot be obtained during sliding. When the particle diameter is 400 nm or more, problems such as an increase in contact resistance, a decrease in adhesion between the surface plating film and the substrate, and a decrease in wear resistance occur. By making the fine particles 4 into spherical small particle diameter particles, the contact reliability is not lowered due to the irregular orientation of the graphite, and a low contact resistance can be obtained at the contact.

  The eutectoid amount of the fine particles in the composite plating layer is preferably set within a range of 5 to 10% by volume. When the amount of eutectoid is 5% by volume or less, it is difficult to improve the slidability and wear by fine particles during sliding, and when it is 10% by volume or more, the slidability, adhesion between the surface plating layer and the substrate, and abrasion resistance Abrasion and contact reliability of contacts are reduced. In the present invention, the amount of fine particles co-deposited in the composite plating layer can be adjusted by fine particle concentration, current density and stirring speed in the plating solution. In the multilayer plating layer 5, the metal plating layer and the fine particle layer are alternately formed to be multi-layered, thereby making it possible to control the amount of eutectoid more strictly.

  The base plating layer 2 formed on the upper part of the conductive substrate 1 improves the adhesion between the conductive substrate 1 and the single-layer plating layer 3 or the multilayer plating layer 5, and the base material component is thermally diffused to the surface layer side. It also functions as a barrier layer that prevents this. When a high melting point metal having a melting point of 1000 ° C. or higher is used for the base plating layer 2, the base plating layer 2 hardly causes thermal diffusion in a heat history of 200 ° C. or lower that is generally received by a contact or switch, and the base material component is It effectively prevents thermal diffusion to the surface layer side. Of the refractory metals, Cu, Ni, cobalt (Co), and iron (Fe) are preferable from the viewpoint of cost and ease of plating. Further, an alloy plating layer containing these elements and a compound layer obtained by alloying by heat treatment after plating are also effective. For example, Cu—Sn, Ni—Sn, Ni—P, Co—P, Ni—Co, Ni -Co-P, Ni-Cu, Ni-Fe, etc. can be mentioned.

  In addition, the base plating layer 2 may be a laminate of two or more layers having different components and characteristics as required. For example, an Ni layer is provided as the first undercoat layer on the upper portion of the substrate 1, Cu is provided as the second undercoat layer thereon, and the single layer plating layer 3 or the multilayer plating layer 5 is provided thereon. Can do. With such a composite plating material, further improvement in adhesion between the base layer and the surface plating layer can be obtained.

  The thickness of the base plating layer 2 is preferably 0.05 to 2.0 μm. When the thickness of the base plating layer 2 is less than 0.05 μm, the effect of preventing thermal diffusion of the base material component to the surface layer side is not sufficiently exhibited. Further, when the thickness of the surface plating layer is larger than 2.0 μm, the effect of preventing thermal diffusion is saturated, and further, there is a high possibility of causing processing cracks during the forming process.

  The above plating materials can be used in place of conventional metal materials used for electrical and electronic parts, and in particular, they are excellent in sliding properties and wear resistance and have high contact reliability. It can be suitably used as a material for a mold contact or switch.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to this.
Each plating material produced in each example was evaluated for friction coefficient, contact resistance, adhesion, durability, and bending workability. The evaluation method is as follows.

Coefficient of friction:
Using a Bowden type friction tester, the dynamic friction coefficient after sliding 100 times reciprocally when the surface of the conductive substrate was slid was evaluated. The measurement conditions were a load of 2.94 N (300 gf) for the Sn plating material, 0.98 N (100 gf) for the Ag plating material, a sliding distance of 10 mm, and a sliding speed of 100 mm / min. The mating material was a 3 mmR steel ball probe.

Contact resistance:
The evaluation was made by measuring the voltage during constant current application. An Ag probe with a tip of 5 mmR was brought into contact with a load of 0.98 N (100 gf) for an Sn plating material and a load of 0.49 N (50 gf) for an Ag plating material, and the voltage at 10 mA energization was measured. The contact resistance was calculated from the average value. Note that the measurement was performed initially and after heating. The heating temperature and time were 120 hours at 160 ° C. for the Sn plating material and 1000 hours at 150 ° C. for the Ag plating material.

Adhesion:
A cross cut was applied from the plating surface, and evaluation was performed by a tape peel test. When the adhesive tape (Teraoka Seisakusho, product name: 631S) is applied to the plated surface after cross-cutting and peeled off, the case where peeling of the plating film is not observed is indicated by ○, and the case where peeling is observed is indicated by ×. evaluated.

durability:
After 100 reciprocating slides, it was evaluated whether exposure of the base material or the base plating layer in the sliding part was observed. The sliding part was observed with a microscope at a magnification of 450 times, and the case where the substrate and the underlying plating layer were not exposed was evaluated as ◯, and the case where the exposure was observed was evaluated as ×.

Bending workability:
90 ° bending (0.2R) was performed at right angles to the rolling direction of the conductive substrate, and the evaluation was made by cracking the plating film at the bent portion. SEM observation was performed at 500 times with respect to the bent part, and the case where no crack was observed in the plating film was evaluated as “◯” and the case where the crack was observed was evaluated as “X”.

[Example 1]
Invention Examples 1 to 346, Comparative Examples 1 to 36
The copper or copper alloy having the chemical composition shown in Table 1 is cast, rolled, and annealed, and pure copper (C1020: base material A), brass (C2600: base material B), phosphor bronze (C5210: thickness) having a thickness of 0.2 mm. Base material C) and a Corson alloy (Cu-Ni-Si: base material D) were produced. These base materials were sequentially subjected to a degreasing treatment and a pickling treatment as a pretreatment for plating, and thereafter a base plating layer was formed, and a surface plating layer was further formed thereon to prepare a plating material. The CXXXX is a type of copper alloy specified by JIS.
The plating conditions for forming each layer are shown in Table 2, and the prepared plating materials are shown in Table 3. The surface side content in Table 3 is the ratio of fine particles contained in up to half the thickness from the outer surface side of the surface plating layer to the total amount. The number of surface plating layers in Table 3 being 2 or 3 indicates that the surface plating layer is a multilayer plating layer. When the number of surface plating layers is 2, there are two metal plating layers and fine particle layers, respectively, and when the number of surface plating layers is 3, there are three layers. When the surface plating layer is a multilayer plating layer, the amount of fine particle eutectoid in Table 3 represents the ratio of the amount of fine particles to the entire multilayer plating layer, and the surface side content is exposed to the outside of the entire multilayer plating layer. It represents the ratio to the total amount of fine particles contained up to half of the thickness from the outermost surface.

The first-stage degreasing treatment was performed by cathodic electrolysis for 30 seconds in a degreasing solution containing 60 g / l of cleaner 160S (manufactured by Meltex) at a liquid temperature of 60 ° C. and a current density of 2.5 A / dm ² . The pickling treatment was performed by immersing in a pickling solution containing 100 g / l of sulfuric acid at room temperature for 30 seconds.

  In the formation of the composite plating layer, when the surface plating layer has a single layer structure as shown in FIG. 1, carbon fine particles are made to correspond to the eutectoid amount shown in Table 3 in the Sn plating bath or Ag plating bath shown in Table 2. The plating solution was added under the same plating conditions using a plating solution to which the above amount was added. When the surface plating layer has a multilayer structure as shown in FIG. 2, a metal plating layer is formed using the Sn plating bath or Ag plating bath shown in Table 2, and the Sn plating bath or Ag plating bath shown in Table 2 is formed thereon. The plating was performed under the same plating conditions using a plating solution in which an amount of eutectoid of carbon fine particles was added to 50% by volume. This operation was repeated to obtain a multilayer structure in which a metal plating layer and a fine particle layer were laminated, and the amount of eutectoid of the entire multilayer plating layer was set to the amount of eutectoid shown in Table 3.

  When fine particles are exposed from the surface of the composite plating layer, the height from the plating layer surface to the fine particle apex is not included in the thickness of the composite plating layer in Table 3.

  About each produced plating material, friction coefficient, contact resistance, adhesiveness, durability, and evaluation of bending workability were implemented. These evaluation results are shown in Table 4.

  As shown in Table 4, all of the plating materials of the examples of the present invention were excellent in adhesion and durability, and good in slidability and contact reliability. In Examples 1 to 86 and 173 to 259 in which the Ni layer was formed as the underlayer, the contact resistance after the heat treatment was low. On the other hand, in Comparative Examples 1, 10, 19 and 28 where the thickness of the base plating layer was thin, the contact resistance after heating was high regardless of the type of the base plating layer. Further, in Comparative Examples 2, 11, 20, and 29 where the thickness of the base plating layer was thick, bending workability was inferior. In Comparative Examples 3, 12, 21, and 30, where the surface plating layer was thin, the friction coefficient, the contact resistance after heating, and the durability were inferior. In Comparative Examples 4, 13, 22 and 31, in which the particle size of the fine particles was small, the friction coefficient was inferior. In Comparative Examples 5, 14, 23, and 32 in which the particle diameter of the fine particles was large, the contact resistance, adhesion, and durability were inferior. In Comparative Examples 6, 15, 24 and 33 in which fine particles were not co-deposited, the friction coefficient was inferior. In Comparative Examples 7, 16, 25, and 34 in which the amount of fine particles co-deposited was large, the contact resistance, adhesion, and durability were inferior. In Comparative Examples 8, 17, 26, and 35 having a small content on the surface side of the fine particles, the friction coefficient was inferior. In Comparative Examples 9, 18, 27 and 36 having a large fine particle surface side content, the friction coefficient, contact resistance and durability were inferior.

DESCRIPTION OF SYMBOLS 1 Conductive base material 2 Base plating layer 3 Single layer plating layer (surface plating layer)
4 Fine particles 5 Multilayer plating layer (surface plating layer)
c Centerline

Claims (7)

At least one base plating layer made of copper, nickel, cobalt, iron, or an alloy containing two or more of these elements is formed on the conductive substrate, and tin, silver, or these elements are contained thereon. A composite plating material in which a surface plating layer made of an alloy is formed,
The surface plating layer contains 5 to 10% by volume of fine particles containing carbon as a main component, and the distribution of the fine particles increases toward the outer surface of the surface plating layer, and is included in the entire surface plating layer. What is more than 50 volume% and not more than 80 volume% with respect to the total volume of microparticles | fine-particles is contained to the half of the thickness from the outer surface of the said surface plating layer, The composite plating material characterized by the above-mentioned.   2. The composite plating according to claim 1, wherein the surface plating layer has a single layer structure including fine particles mainly composed of carbon in a metal plating layer made of tin, silver, or an alloy containing these elements. material.   A multilayer in which the surface plating layer is formed by alternately forming metal plating layers made of tin, silver or an alloy containing these elements and fine particle layers made of fine particles mainly composed of carbon, and including two to three metal plating layers The composite plating material according to claim 1, which has a structure.   4. The composite plating material according to claim 1, wherein the fine particles have an average particle diameter of 20 to 400 nm and are spherical.   The thickness of the base plating layer is 0.05 to 2.0 µm, and the thickness of the surface plating layer is 0.5 to 5 µm. The composite plating material described.   The electrical / electronic component formed using the composite plating material of any one of Claims 1-5.   A fitting-type terminal / connector, a sliding-type or rotary-type contact member or a switch formed using the composite plating material according to claim 1.

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