JP4176081B2 - Contact manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a contact.

  In general, connector contacts use copper or copper alloy as the base material, and nickel plating or nickel alloy plating as the base metal, gold or gold alloy plating as the contact metal, or tin plating or tin alloy plating as the plating layer. In many cases, when a connector is inserted and removed many times, a contact layer by sliding of the contact is provided by providing a lubricating layer of oil, wax, grease, etc. on the contact metal plating layer. Prevents frictional wear on the surface. Such a lubrication layer is formed by immersing the substrate in a solution in which a lubricant is dissolved after a contact metal plating layer is applied, or is formed on the surface by spraying, brushing or the like. Is normal.

  The lubricant applied to the contact part of the connector contact shows a stable lubrication effect even when used for a long period of time when it is engaged and disengaged many times, resulting in unstable contact resistance and contact surface The main purpose is to prevent wear. Especially for IC card and memory card connectors, the contact surface of the contact (contact) surface is not worn even after 10,000 or more times of card insertion / extraction (insertion / extraction), and stable low contact resistance is maintained. Is required to do.

  Conventionally, when applying lubricant to the surface of a contact, it has been devised to increase the coating amount so that as much lubricant as possible remains on the surface. Since there is instability such as adhesion to other parts or contamination, or instability such as increased film resistance at electrical contacts and higher contact resistance, there is a limit to thick coating on the surface, and the amount of coating after all In addition to the problem that the amount of contact cannot be increased sufficiently, the lubricant has fluidity, so that the contact portion can be maintained by holding the connector in a mated / removed state for a long time (using the connector for a long time). The problem is that the lubricant layer will be gradually washed away from the surface (contact surface) of the contact, or the surface of the contact portion by repeating insertion and removal as many as 10,000 times as in the case of application to an IC card connector. (Contact With the problem that the lubricating layer is gradually wiped off from the surface) and disappears and the lubrication effect decreases and deteriorates, making it unusable for practical use. The reality is that it is not possible.

  Therefore, in order to solve such a problem, a method using microcapsules (Patent Documents 1 and 2) is a technique for imparting wear resistance and high lubricity to a contact as an electrical contact member by using lubricating oil. And a method of providing a recess on the surface (see Patent Document 3).

  For example, in the case of the composite plating metal material excellent in wear resistance and slidability according to Patent Document 1 and the manufacturing method thereof, the microcapsules containing the lubricating oil are dispersed in the plating film, and blotting occurs when it is destroyed. In the case of the connector according to Patent Document 2, the polymer film is formed by the contact of the mating contact using the lubricant covered with the polymer film insoluble in the organic solvent. By tearing, the connector contact resistance can be improved. Further, in the case of the method for forming a hard coating for a sliding member according to Patent Document 3, the release material is detached from the hard coating containing the release material formed on the substrate, and a fine recess is formed on the surface of the hard coating. Thus, it is possible to efficiently form a hard film having lubricating oil retaining pits.

JP-A-6-330392 (Abstract, FIG. 2, Paragraph [0023]) Japanese Patent Laid-Open No. 5-266638 (Summary, FIG. 1) JP-A-6-57414 (summary, FIG. 4)

  In the case of the well-known techniques according to Patent Documents 1 to 3 for imparting wear resistance and high lubricity to the above-described electrical contact member using a lubricating oil, each of them is actually sufficient wear resistance or It is difficult to easily produce a high-quality product having high lubricity with good workability and productivity.

  That is, in the case of the technique according to Patent Document 1, it is necessary to improve the plating treatment liquid in order to prepare the microcapsules and disperse the microcapsules in the plating treatment liquid. As the number of chemicals used increases, the workability and productivity in production are not only excellent, but also inferior to the well-known plating process in terms of safety, and the microcapsules themselves are lubricating oils. There is also a problem that the hardness of the film when the composite plating is applied to the metal becomes soft compared to the case where the composite plating is not performed, resulting in a decrease in surface hardness and a decrease in wear resistance. is there.

  In the case of the technique according to Patent Document 2, preparation of microcapsules is necessary as in the case of Patent Document 1, and the material must be selected. In addition, there is a problem that workability, productivity, and safety at the time of manufacture are not excellent due to complicated selection of materials.

  Furthermore, in the case of the technique according to Patent Document 3, a process for applying a surface of the release substance before the plating process and a process for releasing the release substance after the plating process are required. There is a problem that workability and productivity in manufacturing are not excellent.

  The present invention has been made to solve such problems, and its technical problem is to provide a high-quality contact having sufficient wear resistance and high lubricity, a connector to which the contact is applied, and a known plating apparatus. It is another object of the present invention to provide a contact manufacturing method that can use a plating solution as it is and can easily manufacture a high-quality product with good workability and productivity with safety.

According to the present invention, at least the copper alloy base material containing at least tin that becomes a contact material having a predetermined shape provided with a contact portion provided for connection with the counterpart electrical contact member is heated and oxidized to at least An oxidation treatment step for forming an oxide layer on the surface including the contact portion, and a surface including at least the contact portion by immersing the base material in a fluorine compound solution adjusted to have a hydrogen ion concentration pH within a predetermined range A recess nucleation step of forming a plurality of recess nuclei by a chemical reaction with the oxide layer, and at least the recess nuclei by electroplating a base metal on the surface of the substrate including at least the contact portion A plurality of minute recesses having a diameter of 1 due to generation of bubbles due to stagnation of hydrogen gas generated as a result of deposition of the plating film at locations including the nuclei of the plurality of recesses formed in the forming step. By forming the base metal and the recess forming step so as to be in the range of μm to 100 μm, and electrolytically or electrolessly plating the contact metal on the surface including at least the contact portion of the substrate, at least the base metal And a contact metal forming step of forming a metal for contact with a plating film on a portion including a plurality of recesses formed in the recess forming step, and fluidity with respect to the surface including at least the contact portion in the substrate. By applying or immersing a lubricant substance comprising any one of a lubricant having a lubricant, solid lubricant fine particles, and a lubricant containing solid lubricant fine particles, at least the lubricant substance is formed in the plurality of recesses formed in the contact metal forming step. A contact manufacturing method is obtained, which has a lubricating substance retention step of obtaining a contact by retaining and retaining the lubricant.

  According to the present invention, in the contact manufacturing method, in the recess nucleation step, the predetermined range at the hydrogen ion concentration pH is set to a range of 2 to 5, and hydrofluoric acid is used as the fluorine compound solution. , Using at least one of acid ammonium fluoride, potassium acid fluoride, and sodium fluoride, in the base metal and recess forming step, using nickel plating or nickel alloy plating as the base metal, contact In the metal forming step, a contact manufacturing method using gold plating or gold alloy plating, or tin plating or tin alloy plating as the contact metal is obtained.

  Furthermore, according to the present invention, in any one of the above contact manufacturing methods, the lubricating substance retention step includes at least one of paraffinic, olefinic, esteric, etheric oil, wax, and grease as a lubricant. And a contact manufacturing method using solid lubricant fine particles containing at least one of molybdenum disulfide, PTFE, and graphite fluoride having a particle diameter of 1 μm or less.

  In the case of the contact of the present invention, at least a part of the entire surface including the contact portion or a plurality of minute recesses are formed on the entire surface, and the recess includes fluid lubricant, solid lubricating fine particles, or solid lubricating fine particles. Basically, the lubricant is retained and retained by any one of the lubricants, and the diameter of the recess is in the range of 10 μm to 100 μm. The particle size of the solid lubricating fine particles is retained and retained in the recess. Since it is specified to be 1 μm or less so that it can be easily dispersed and dispersed in the lubricant, a stable contact state can be maintained even when used many times of mating / removing, and sufficient wear resistance In addition, a high-quality product having high lubricity can be obtained. As a result, a high-quality connector having sufficient wear resistance and high lubricity can be obtained in the same manner by arranging and holding a predetermined number of such contacts on the insulator or the housing. In the contact manufacturing method of the present invention, first, in the oxidation treatment step, a copper alloy base material containing tin, which becomes a contact material having a predetermined shape, is heated and oxidized to form an oxide on the surface. In the subsequent recess nucleation step, the substrate is immersed in a fluorine compound solution adjusted so that the hydrogen ion concentration pH is within a predetermined range, and a plurality of recess nuclei are formed by a chemical reaction with the oxide layer. Furthermore, in the base metal and recess forming step, the base metal is electroplated onto the surface including at least the contact portion of the base material, and bubbles caused by the retention of hydrogen gas generated along with the deposition of the plating film are generated. After forming a plurality of minute recesses so that the diameter is in the range of 10 μm to 100 μm as described above, in the contact metal forming step, the contact metal with respect to the surface of the substrate Is formed by plating film, and in the last lubricating substance retention step, it depends on any one of lubricant having fluidity to the surface of the base material, solid lubricating fine particles, or lubricant containing solid lubricating fine particles. Since the contact is obtained by applying or dipping the lubricant and retaining the lubricant in each recess to obtain the contact, the contact obtained through each of these steps is based on a copper alloy material containing at least tin. The base metal and the contact metal are coated on the surface including at least the contact portion of the base material, and each concave portion is formed on the surface including the contact portion of the contact metal. In the lubricant retention process, the lubricant contains one or more of paraffinic, olefinic, esteric and etheric oils, waxes and greases. In addition to the use of such a material, and using a solid lubricating fine particle containing one or more of molybdenum disulfide, PTFE, and graphite fluoride having a particle diameter of 1 μm or less, a known plating apparatus or The treatment liquid can be used as it is, and the above-described high-quality products (contacts) can be manufactured easily with safety and good workability and productivity.

  The contact according to the best mode of the present invention has a predetermined shape provided with a contact portion used for connection with the mating electrical contact member, and at least a part of or the entire surface including the contact portion has a plurality of minute contacts. Concave portions are formed, and in each of the concave portions, a lubricant substance is retained and held by any one of a fluid lubricant, solid lubricating fine particles, and a lubricant containing solid lubricating fine particles. However, the plurality of recesses here have a diameter in the range of 10 μm to 100 μm, and the particle size of the solid lubricating fine particles is 1 μm or less in consideration of the size of the recesses and the dispersibility when contained in the lubricant. It is preferable to make it. The lubricant used here includes one or more of paraffinic, olefinic, esteric, and etheric oils, waxes, and greases, and the solid lubricating fine particles are one of molybdenum disulfide, PTFE, and graphite fluoride. It is preferable to include two or more. As in the case of the known structure, the basic structure of such a contact is based on a copper alloy material containing at least tin, and the base metal and the contact metal are provided on the surface including at least the contact portion of the base material. It is preferable that each recess is formed on the surface including the contact portion of the contact metal.

  That is, the present invention is any one of a lubricant having a known fluidity, a solid lubricating fine particle, or a lubricant containing a solid lubricating fine particle with respect to a minute recess formed on the surface of the contact portion of the connector contact. It has been found that long-term stable contact can be obtained even under repeated insertion / extraction use conditions by retaining and retaining the lubricating substance. The stable lubrication effect is that the lubricant stored in the minute recesses is retained for a long period of time, and it is continuously supplied to the contact part at the time of mating / removing to prevent disappearance, so that it can be used for a long time In a state where the solid lubricating fine particles are realized and retained in the recesses, a direct contact between metals is avoided and friction and wear are prevented, so that a lubricating effect is exhibited. Therefore, since the contact is such that the lubricating substance is stably retained and retained in at least the recesses formed on the surface of the contact portion, a stable contact state can be obtained even in the use of multiple engagements / disengages. High quality products with sufficient wear resistance and high lubricity are maintained.

  In the case of the contact of the present invention, a conventional lubricant and solid lubricating fine particles are used, and even under use conditions in which a large number of times (1000 times to 20000 times) are engaged and detached, A stable contact state can be maintained. By the way, such a contact is configured as a connector by arranging and holding a predetermined number of contacts in an insulator or a housing, and in such a connector as well, sufficient wear resistance and high lubricity are similarly provided. It will be of high quality.

  FIG. 1 shows an electron microscopic (SEM) photograph (secondary electron image magnified 150 times) of a structure including minute concave portions formed on the surface of a connector contact according to the preferred embodiment of the present invention. It is.

  In FIG. 1, a state in which minute concave portions are formed on the surface of the contact portion (contact surface) in the contact is shown by a secondary electron image of 150 times. In addition, the diameter of the recessed part formed here exists in the range of about 10 micrometers-100 micrometers, and the depth comprises the shape depending on the thickness of the nickel plating layer of a base metal. In these recesses, a lubricating substance by any one of fluid lubricant, solid lubricant fine particles, and lubricant containing solid lubricant fine particles is retained and retained, which makes it stable over a long period of time. Shows a lubricating effect.

  Incidentally, the reason why the lubricating effect can be maintained for a long time by retaining the lubricating substance in the recess is considered as follows.

  That is, a lubricant material by any one of a fluid lubricant, solid lubricant fine particles, and a lubricant containing solid lubricant fine particles is applied to a part or the entire surface (contact surface) including at least a contact portion as usual. By doing so, not only a lubricating layer is formed on the contact surface, but also extra lubricating material is stored in the minute recesses, and the lubricating effect is exerted by the lubricating layer on the contact surface at the initial sliding of the contact. As the number of sliding operations increases, the lubricating layer begins to thin at the sliding part.However, if a large number of minute concave parts are provided to store a large amount of lubricant so that the lubricating effect can be maintained for a long period of time, the lubricating layer can be stored. Since the lubricant is newly supplied, the lubricant does not disappear from the sliding portion. In addition, the lubrication substance used here can use the substance generally used as mentioned above.

  In addition, when a lubricant in which solid lubricating fine particles are dispersed is applied to the surface of the contact portion as a lubricating substance, the solid lubricating fine particles are held in the recesses to prevent direct contact between metals and prevent sliding parts. Reduces frictional wear. Since the solid lubricating fine particles do not disappear from the contact surface when held in the recesses, a stable lubricating effect can be obtained over a long period of time. The size of the solid lubricating fine particles is preferably 1 μm or less with respect to the diameter range of 10 μm to 100 μm of the recesses as described above in consideration of the size of the minute recesses and the dispersibility in the lubricant. . In addition, the well-known thing as mentioned above can be used for the solid lubricating fine particle used here.

  In the following, a contact manufacturing method including a step of forming a minute recess with respect to the surface of the contact portion will be described on the assumption that a copper alloy material containing at least tin is used as the contact substrate.

  Prior to the manufacture of the contacts, the dirt due to organic substances such as press oil and human sebum is completely removed from the surface of the base material having a predetermined shape by a known degreasing treatment.

  Therefore, first, an oxidation treatment process is performed in which an oxide layer is formed on the surface including at least the contact portion by heating and oxidizing the substrate in a temperature range of 100 ° C. to 200 ° C. This oxide layer contains a compound of copper and tin. The heating temperature range is not practical because it takes too much time to form an oxide layer when heated at a temperature of 100 ° C. or less, and a thick and strong oxide layer is immediately formed at a temperature of 200 ° C. or more. This is not preferable because it inhibits the formation of a normal plating film. Therefore, it is preferable to heat in a temperature range of 100 ° C to 200 ° C. Incidentally, the required heating time depends on the heating temperature. For example, it is appropriate that the heating time is about 10 hours at 120 ° C. and about 1 hour at 140 ° C.

  Next, fluorine containing at least one or more of hydrofluoric acid, acidic ammonium fluoride, acidic potassium fluoride, sodium fluoride whose base material was adjusted to have a hydrogen ion concentration pH in the range of 2 to 5 By immersing in the compound solution, a recess nucleation step is performed in which nuclei of a plurality of recesses are formed on the surface including at least the contact portion by a chemical reaction with the oxide layer. When the substrate is immersed in the fluorine compound solution in the region of the hydrogen ion concentration pH here, the copper-based oxide is dissolved, but the tin-based oxide remains on the surface as an insoluble product (the tin-based oxide is It is understood that a compound is formed by a chemical reaction with fluorine ions simultaneously with dissolution by the fluorine compound solution), and a concave nucleus is formed in the residue portion. In addition, oxides other than tin-based oxides form fluorine ions and complexes and dissolve in the solution. Here, if the hydrogen ion concentration pH is lower than 2, the insoluble product resulting from the tin-based oxide dissolves in the solution and nuclei are not formed. If the hydrogen ion concentration pH is higher than 5, oxides other than tin Since the problem of the adhesion of the plating film occurs when plating is performed in the subsequent formation of the underlying metal and the recess, the dissolution of the metal is hindered. Therefore, the hydrogen ion concentration pH is preferably in the range of 2-5. Incidentally, the treatment of immersing the substrate in the fluorine compound solution can be performed at room temperature, but it is better to perform the treatment under a temperature condition of about 50 ° C. because the dissolution reaction of oxides other than the tin-based oxide is slow.

  Subsequently, at least a portion including the nucleus of each recess formed in the previous recess nucleus forming step by electroplating nickel plating or nickel alloy plating as a base metal on the surface including at least the contact portion in the base material In contrast, a base metal and recess forming step for forming a plurality of minute recesses in a range of 10 μm to 100 μm by the generation of bubbles due to the retention of hydrogen gas generated with the deposition of the plating film carry out. Here, a minute concave portion is formed on the surface including the contact portion by electroplating of nickel plating or nickel alloy plating, and this is a minute insolubility generated by the reaction between the above tin-based oxide and fluorine ions. This is because hydrogen gas generated along with the deposition of the plating film stays in the product portion. That is, the nickel plating layer is formed on the surface including the contact portion by the deposition of the plating film electroplated with nickel plating or nickel alloy plating, but the hydrogen gas generated along with the deposition of the plating film is an insoluble product. It stays with the part as a nucleus, and produces microbubbles. A concave portion is formed in the bubble portion without forming a nickel plating layer. However, the depth of the recess depends on the thickness of the nickel plating layer, and the thickness of the nickel plating layer requires 0.5 μm or more, and the recess is hardly formed at a thickness less than this.

  Further, by subjecting the surface of the base material including at least the contact portion to gold plating or gold alloy plating as a contact metal, or tin plating or tin alloy plating by electrolytic plating or electroless plating, at least the previous base metal and recesses A contact metal forming step is performed in which a metal for contact is formed by a plating film on a portion including each recess formed in the forming step. Here, a contact metal of either gold plating or gold alloy plating or tin plating or tin alloy plating is further formed by electrolytic plating or electroless plating on the nickel plating layer in which the recess is formed. In this case, the bottom of the concave portion of the nickel plating layer is covered with a very thin plating to protect the concave portion. Prior to the contact metal forming step, it is also possible to reinforce the protection of the concave portion by adding a thin nickel plating layer by repeating the base metal and concave portion forming step again to perform plating.

  Finally, by applying or immersing a lubricating substance by any one of a lubricant having fluidity with respect to the surface including at least the contact portion in the substrate, solid lubricating fine particles, and solid lubricating fine particles, At least a lubricating substance retention step is performed in which a lubricating substance is retained and retained in each of the recesses formed in the contact metal forming step to obtain a contact. In this case, however, a lubricant containing at least one of paraffinic, olefinic, esteric, and etheric oils, waxes, and greases is used, and solid lubricating fine particles that are easily dispersed in the lubricant have a particle size of 1 μm. A material containing one or more of the following molybdenum disulfide, PTFE, and graphite fluoride is used.

  In the contact obtained through these steps, the larger the number of minute recesses, the more lubricant can be retained and the more solid lubricating fine particles can be retained. A lubricating effect can be exhibited. In each step described above, the number of recesses can be increased by several methods described below.

  That is, it is possible to increase the fluorine compound concentration in the fluorine compound solution used in the above-described recess nucleation step. If the fluorine compound concentration is high, the amount of fluorine ions that react with the tin-based oxide increases, and the amount of insoluble products increases, so the number of concave portions increases. Further, the time for immersing the substrate in the fluorine compound solution may be lengthened. In this case, the reaction time between the tin-based oxide and the fluorine ions is prolonged, and the formation of insoluble products is promoted, so that the number of concave portions increases. Furthermore, a plating film for forming a nickel plating layer on the base material in the base metal and recess formation step is performed under high current density conditions. When the plating film is formed under a high current density condition, the amount of hydrogen gas generated increases, so the number of recesses increases.

  Incidentally, the minute concave portion can be partially formed at a predetermined position such as the contact portion instead of the entire surface of the contact. In this case, after using two types of fluorine compound solutions having different hydrogen ion concentrations pH and immersing the contact base material in the first fluorine compound solution having a hydrogen ion concentration pH adjusted to a range of 2 to 5, The portion where the recess is not formed is immersed in the second fluorine compound solution adjusted so that the hydrogen ion concentration pH is 2 or less. As a result, an insoluble product can be formed only at a predetermined location where the concave portion including the contact portion is to be formed, and finally a large number of minute concave portions can be formed at the predetermined location.

  In short, the contact obtained through each of the steps is based on a copper alloy material containing at least tin, and the surface of the substrate including at least the contact portion is coated with the base metal and the contact metal. In addition to having a well-known structure, it has a basic structure in which each recess is formed on the surface including the contact portion of the contact metal, and at least the lubricating substance stays in the minute recess formed on the surface of the contact portion. By being held, the contact surface of the contact portion has sufficient lubrication effect even under use conditions that extend and insert many times (1000 times to 20000 times) that could not be realized by the conventional method of forming a lubricating layer. Maintain high quality products. In addition, a general plating method in which the above-described base metal and concave portion forming process and contact metal forming process are conventionally performed can be applied, and a well-known plating apparatus and process without requiring special chemicals or equipment. The liquid can be used as it is, and it can be manufactured by forming a minute recess partly or entirely including the contact part on the surface and retaining the lubricating substance in each recess part without questioning the shape. Therefore, as a result, a product with higher quality than that in the case of the technique proposed as a well-known technique represented by Patent Documents 1 to 3 can be manufactured safely and easily with good workability and productivity.

  Several examples and comparative examples will be described below, and the contact of the present invention will be specifically described including its manufacturing process.

  In Example 1, first, phosphor bronze for a spring [C5191-P-1 / 2H; Harada as a base material of a contact subjected to cathodic electrolytic degreasing using a commercially available alkaline solution [for example, F-1550 of Yuken Industry Co., Ltd.] A U-shaped test piece or a flat coupon made of wrought copper) was subjected to an oxidation treatment step of forming an oxide layer by heating in a 140 ° C. oven for 1 hour to carry out an oxidation treatment.

  Next, as the recess nucleation step, the base material on which the oxide layer is formed is added to 20 g / liter (g / L) of an acidic ammonium fluoride solution in which the hydrogen ion concentration pH is adjusted to about 4 under a temperature condition of 50 ° C. After forming a plurality of concave nuclei on the surface by dipping for 20 seconds, a plating layer was formed on the surface of the base material through a base metal, concave portion forming step, and contact metal forming step by electrolytic plating.

In the base metal and recess formation step, nickel plating is applied to the surface of the base material as a base metal by electrolytic plating in which a brightener is added to a sulfamic acid-based bath at a current density of 10 A / dm ² for 180 seconds. (The nickel plating layer has a plurality of minute recesses as described above.) In the contact metal formation process, the current density is obtained by adding a brightener to a citric acid-based bath. Cobalt hard gold plating as a contact metal is formed on the surface of the substrate to a thickness of about 0.2 μm by electroplating for 30 seconds at 4 A / dm ² (the cobalt hard gold plating layer is formed with minute recesses as described above. Thinly coated).

  Furthermore, as a lubricating substance retention step, a concentration of 3% by volume using an organic solvent (n-propyl bromide) is applied to a base material (U-shaped test piece or flat coupon) on which a cobalt hard gold plating layer is formed. A diluted lubricant as a commercially available lubricant (for contact part of contact and based on alpha olefin oil) is applied by squeezing treatment and retained in each recess to form the contact according to Example 1 Obtained.

  In Example 2, the same procedure was followed except that the acidic ammonium fluoride solution used in the recess nucleation step in Example 1 was different in concentration from 100 g / liter (g / L). Contact according to 2 was obtained.

  In Example 3, a contact according to Example 3 was obtained according to the same procedure except that the immersion time of the acidic ammonium fluoride solution used in the concave nucleus formation step in Example 1 was set to 120 seconds.

[Comparative Example 1]
In Comparative Example 1, the base material (U-U test piece or flat coupon) that was not subjected to the oxidation treatment by heating in the oxidation treatment step in Example 1 above was used, and the lubricant was not applied in the lubricant retention step. A contact according to Comparative Example 1 was obtained according to the same procedure as described above.

[Comparative Example 2]
In Comparative Example 2, a contact according to Comparative Example 2 was obtained by further applying a lubricant in the lubricating substance retention step to the contact obtained in Comparative Example 1.

[Comparative Example 3]
In Comparative Example 3, a contact according to Comparative Example 3 was obtained according to the same procedure except that the immersion treatment of the acidic ammonium fluoride solution used in the concave nucleus formation step in Example 1 was not performed.

[Comparative Example 4]
In Comparative Example 4, the same procedure was followed as in Comparative Example 4, except that 10% by volume of sulfuric acid was added to the acidic ammonium fluoride solution used in the recess nucleation step in Example 1 above, and immersion was performed. Such contact was obtained.

  Therefore, first, regarding the contact samples according to Examples 1 to 3 and Comparative Examples 1 to 4, the number of minute recesses formed on the surface of the flat coupon as a base material is enlarged about 50 times with an optical microscope on both sides. The number of recesses formed per unit area was calculated by dividing the number of recesses formed by the area of the plating layer, and the number of recesses formed was evaluated by comparing the results.

  Next, for the contact samples according to Examples 1 to 3 and Comparative Examples 1 to 4, a frictional wear test was performed on a U-shaped test piece as a base material. FIG. 2 is a schematic perspective view shown for explaining the state of the friction and wear test on the contact samples according to Examples 1 to 3 and Comparative Examples 1 to 4. FIG. Here, one (upper part) of the U-shaped test piece is the fixed-side sample 10, and the other (lower part) is the movable-side sample 20 according to Examples 1 to 3 and Comparative Examples 1 to 4. This shows that the frictional wear test (lubricating effect) is examined by causing the sample 20 to slide while intersecting with the fixed-side sample 10 by 90 degrees. However, the friction and wear test conditions were a sliding distance of 3 mm at a temperature of 25 ° C., a sliding speed of 1 mm / s, and a contact load of the fixed sample 10 to the movable sample 20 of 0.98 N.

Table 1 shows a summary of the number of recesses formed and the evaluation results of the frictional wear test for each of the contact samples according to Examples 1 to 3 and Comparative Examples 1 to 3 according to each condition. However, the criteria for determining the number of recesses formed are those with a large number of recesses (specifically 20 pieces / cm ² or more) indicated by ◎ and those with normal recesses (specifically 10). pieces / cm showed about ²⁾ with ○ mark indicates what recess is not formed in the × mark, the criterion of the friction wear test, the dynamic friction coefficient stable low at 20000 times of sliding, lubrication effect Is indicated by a circle, and when it is slid about 10,000 times, the lubrication effect is lost, and a triangle is indicated by a triangle. The dynamic friction coefficient becomes unstable immediately after the start of sliding, and the lubrication effect immediately disappears. Things are indicated by crosses. The hydrogen ion concentration pH of the acidic ammonium fluoride solution is a value obtained when the acidic ammonium fluoride solution is diluted 10 times with distilled water.

  From Table 1, the contact samples according to Examples 1 to 3 in which the recesses are formed exhibit a much better lubricating effect than the contact samples according to Comparative Examples 1 to 3 in which the recesses are not formed. I understand that.

  FIG. 3 shows the results of the frictional wear test on the contact samples according to Example 1 and Comparative Examples 1 and 2 in terms of the dynamic friction coefficient with respect to the number of sliding times. In FIG. 3, a lower kinetic friction coefficient on the vertical axis means a higher lubricating effect. From FIG. 3, in the sample of Comparative Example 1 in which the lubricant as a lubricant was not applied without being subjected to the oxidation treatment, the dynamic friction coefficient rapidly increased immediately after sliding, and as in Comparative Example 2 Even if a sample coated with a lubricant is not oxidized and has no recess on the surface, the sliding coefficient exceeds 7000 times, the coefficient of dynamic friction begins to increase, and no lubricating effect is exhibited. In the sample of Example 1 in which a concave portion was formed on the surface and a lubricant as a lubricant was applied, the low dynamic friction coefficient was maintained even when the number of sliding was 20000, and a stable lubricating effect was obtained. It can be seen that it is being demonstrated.

  FIG. 4 shows the result of the frictional wear test over time for the contact samples according to Example 1 and Comparative Example 4 described above in relation to the dynamic friction coefficient with respect to the number of sliding times. However, in this case, each sample was left to stand for 3 months after adjusting the concentration of the lubricant as a lubricant to 5 vol% in the lubricant retention step, and then subjected to a frictional wear test in the same procedure as described above.

  From FIG. 4, in the sample of Comparative Example 4, the dynamic friction coefficient gradually increased from the small number of sliding times, whereas in the sample of Example 1, the result of the frictional wear test immediately after coating. It can be seen that the initial dynamic friction coefficient is slightly larger than that of, but even if the number of sliding times is 20000, a low dynamic friction coefficient is maintained and a stable lubricating effect is exhibited.

1 shows an electron micrograph of a structure including a minute recess formed on a surface of a connector contact according to a best embodiment of the present invention. It is the perspective schematic diagram shown in order to demonstrate a friction abrasion test with respect to the sample of the contact which concerns on Examples 1-3 and Comparative Examples 1-4 of this invention. The friction abrasion test result about the sample of the contact which concerns on Example 1 of this invention and Comparative Examples 1 and 2 is shown by the relationship of the dynamic friction coefficient with respect to the frequency | count of sliding. The result of the frictional wear test with respect to the sample of the contact which concerns on Example 1 of this invention and the comparative example 4 is shown by the relationship of the dynamic friction coefficient with respect to the frequency | count of sliding.

Explanation of symbols

10 Fixed side sample 20 Movable side sample

Claims (3)

  By heating and oxidizing a copper alloy base material containing at least tin, which becomes a contact material having a predetermined shape provided with a contact portion provided for connection with the counterpart electrical contact member, on the surface including at least the contact portion An oxidation treatment step for forming an oxide layer on the surface, and by immersing the base material in a fluorine compound solution adjusted to have a hydrogen ion concentration pH within a predetermined range, the surface including at least the contact portion A recess nucleation step of forming a plurality of recess nuclei by a chemical reaction with the oxide layer; and at least the recess nuclei by electroplating a base metal on a surface of the substrate including at least the contact portion. A plurality of minute recesses due to the generation of bubbles due to the stagnation of hydrogen gas generated along with the deposition of the plating film at the locations including the nuclei of the plurality of recesses formed in the forming step. Forming a base metal and a recess forming step so that the diameter is in a range of 10 μm to 100 μm, and electroplating or electrolessly plating the contact metal on the surface of the substrate including at least the contact portion A contact metal forming step of forming a metal for contact with a plating film on at least the base metal and a portion including the plurality of recesses formed in the recess forming step; and at least the contact portion in the base material Formed at least in the contact metal forming step by applying or dipping a lubricant material of any one of a lubricant having fluidity with respect to the surface containing solid, solid lubricant fine particles, and a lubricant containing solid lubricant fine particles And a lubricating substance retention step for obtaining a contact by retaining the lubricating substance in the plurality of recessed portions. Method of manufacturing a door. 2. The contact manufacturing method according to claim 1 , wherein, in the recess nucleation step, the predetermined range at the hydrogen ion concentration pH is set to a range of 2 to 5 and hydrofluoric acid is used as the fluorine compound solution. In addition, in the step of forming the base metal and the recess, nickel plating or nickel alloy plating is used as the base metal. In the contact metal forming step, the contact metal is made of gold plating, gold alloy plating, tin plating or tin alloy plating. 3. The method for manufacturing a contact according to claim 1 , wherein the lubricant containing step includes using at least one of paraffinic, olefinic, esteric, etheric oil, wax, and grease as the lubricant. In addition, a contact manufacturing method using the solid lubricating fine particles containing at least one of molybdenum disulfide, PTFE, and graphite fluoride having a particle diameter of 1 μm or less.