JPH042676B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a surface treatment agent applied to a plating surface of an electrical contact such as an electrical connector contact or an electrical switch contact. Conventionally, electrical contacts such as electrical connector contacts and electrical switch contacts are coated with silver plating, gold plating, nickel plating, etc. on a copper alloy base.
Tin plating, solder plating, etc. are applied, and a surface treatment agent is further applied to the plated surfaces for the purposes of rust prevention, sealing (sealing pinholes in plating), and lubrication. For example, as disclosed in FIGS. 1 to 3, electrical contacts or female contacts 1a of an electrical connector,
The male contacts 2a are incorporated into the female connector housing 1 and the male connector housing 2, respectively, and connect or disconnect an electric circuit by fitting or removing the connectors. These female contacts 1a and male contacts 2a are
It is usually made of copper alloy, which is a conductive material. For example, the female contact 1a may be made of springy phosphor bronze or beryllium copper, and the male contact 2a may be made of brass. The surface of the base of these contacts is coated with silver plating, gold plating, nickel plating, tin plating, solder plating, etc., as described above, in order to protect the base surface and reduce the contact resistance of the contacts. are applied depending on the purpose. However, the surfaces of the contacts 1a and 2a are worn out due to repeated fitting and disconnecting operations of the connectors, resulting in increased contact resistance and problems such as heat generation. In addition, the plated surface is exposed to oxidizing or sulfurizing components (e.g. H ₂ S, SO ₂ ) in the atmosphere over time.
etc.), which generate oxides or sulfides, and these products impair electrical conduction, increase contact resistance, and also increase the mating and uncoupling forces of the connector, making it inconvenient to use the connector. arise. Furthermore, recently there has been a trend to reduce the thickness of plating on contacts in order to save resources on plating materials, and when plating is applied thinly in this way, pinholes inevitably occur. Then, the pinhole further causes corrosion of the substrate, and the corrosion causes an increase in contact resistance, an increase in fitting force, and an increase in detachment force, resulting in further problems. In particular, recently, connectors have been miniaturized due to demands from users for the connector industry to be lighter, thinner, and shorter. , there is an increasing demand for connectors with weak contact pressure at the contact portions 1b and 2b of the contacts, which tends to increase contact resistance. Therefore, conventional plating treatment alone cannot solve the problem, and there is a demand for applying a surface treatment agent with rust prevention, pore-sealing, and lubricity to the plating surface. Conventionally, hydrocarbon oils such as vaseline have been used for lubricating purposes, and heterocyclic organic compounds such as benzotriazole and 2-aminobenzazole, and chromic acid compounds have been used for rust prevention and pore sealing purposes. . However, although these surface treatment agents were somewhat effective, they did not meet the demands of the industry. Particularly in recent connectors whose contacts have low contact pressure, this increases the contact resistance, making them impractical and unusable. Therefore, in the connector industry, there is a need for a surface treatment agent that has rust prevention, pore sealing, and lubrication that does not increase contact resistance even when contact pressure is low. In view of the above circumstances, the present inventors have conducted intensive research and found that a composition consisting of perfluoropolyether and alkyl mercaptan can improve lubricity and pore sealing without increasing contact resistance even in products with low pressure bonding force. It has been found that the corrosion resistance and rust prevention properties are significantly improved. Furthermore, when an oil-soluble fluorosurfactant or an ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol is added to a composition consisting of perfluoropolyether and alkyl mercaptan, It has been found that the lubricity, pore sealing properties, and rust prevention properties are further improved compared to the two-component composition system described above without increasing contact resistance. The present invention has been made based on the above findings, and the gist thereof is a surface treatment agent for plating electrical contacts containing 0.002 to 0.5 parts by weight of alkyl mercaptan per 1 part by weight of perfluoropolyether. It is in. The present invention will be explained below. The perfluoropolyether used in the present invention has the structural formula shown below, and these are used alone or in combination. The molecular weight has a range as shown by m and n. However, 5≦m≦100, 5≦n≦200 In addition, alkyl mercaptan has a carbon number of
It is a linear or branched thiol represented by C ₆ H ₁₃ SH to C ₁₈ H ₃₇ SH, and these can be used alone or in combination. The oil-soluble fluorine-based surfactant is RfSO ₂ NH (CH ₂ CH ₂ O) _o H or RfO (CH ₂ CH ₂ O) _o H (However, Rf: C ₆ F ₁₃ - _{C 12} F ₂₅ , 5≦ n≦200) These nonionic surfactants can be used alone or in combination. 2, 4, 7,
The ethylene oxide adduct of 9-tetramethyl-5-decyne-4,7-diol is However, it is a compound represented by (X+Y)=3 to 30, and there are various grades depending on the number of moles of ethylene oxide added. These are Surf Inol 440 from Air Products,
These are sold under the trade names Surf-Inol 465 and Surf-Inol 485, and in the present invention, these are used alone or in combination. The mixing ratio of each of the above chemicals is 1 part by weight of perfluoropolyether to alkyl mercaptan.
0.002-0.5 parts by weight. If you need to further improve performance,
Per 1 part by weight of perfluoropolyether, 0.002 to 0.5 parts by weight of alkyl mercaptan, 0.1 to 2.0 parts by weight of oil-soluble fluorosurfactant, or 2,4,7,9-tetramethyl-5-decyne-4,7-diol 0.1 to 2.0 parts by weight of the ethylene oxide adduct is suitable. Alkyl mercaptan for perfluoropolyether, and oil-soluble fluorosurfactant or 2,4,7,9-tetramethyl-5-decyne-
If the amount of the ethylene oxide adduct of 4,7-diol is more than the above value, the contact resistance value will increase and it will not be practical. If it is less than the above value, the lubrication, rust prevention, and pore sealing effects will be reduced. In order to attach the above drug components to the connector, dissolve them in a suitable organic solvent at a predetermined weight ratio, and add the solution to the contact parts 1b and 2b of the contact.
After soaking, air dry at room temperature. The above organic solvent is not particularly limited as long as it dissolves the above two or three effective components, but from the viewpoint of handling safety, nonflammability, volatility, etc., Freon 113 (CClF ₂ / CCl ₂ F) is preferred. The concentration of the solvent is best within the range of 1 to 5% by weight based on the concentration of perfluoropolyether. If the concentration is higher than 5%, it is not only uneconomical, but also makes the coated contact surface sticky and difficult to handle. If the concentration is lower than 1%, sufficient lubrication, rust prevention, and sealing effects cannot be obtained. . Next, the present invention will be explained in more detail by showing Examples and Comparative Examples. Examples and Comparative Examples The contact parts 1b and 2b of male and female contacts of the same shape, plated with gold or silver, were immersed for 30 seconds in a solution in which various surface treatment agents were dissolved in a predetermined weight ratio and concentration, and then air-dried at room temperature. The following tests were conducted. (1) Contact resistance Male and female contacts were bonded, and the electrical resistance of the bonded portion was measured using a resistance meter. (2) Mating and disconnection test The female contact was fixed, and the male contact was repeatedly mated and disconnected from the female contact. 1000
After repeating the test several times, the fitting force was measured using a load-displacement tester. (3) Rust prevention and pore sealing test Place the terminals coated with surface treatment agent outdoors in a place out of direct sunlight for 6 months in the case of silver plating.
The gold plating was left for 12 months, and the degree of discoloration was then observed with the naked eye. The ranking of rust prevention and pore sealing effects is shown as follows. No discoloration>Slight discoloration>Mild discoloration>Moderate discoloration>Extreme discoloration The results of the test are shown in Tables 1 and 2. As is clear from the results, it can be seen that the composition according to the present invention is significantly superior overall. The above embodiments have been described with respect to electrical connector contacts, but they are also applicable to all operating electrical contacts, such as electrical switch contacts, relay contacts, and tuner contacts.

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【table】 Needless to say, it's effective.

[Brief explanation of drawings]

1A and 1B are perspective views of male and female connectors, FIG. FIG. 3 is a side view showing a fitted state of male and female contacts. 1...Female connector, 1a...Female contact,
1b...Contact part (silver or gold plated part), 2...male connector, 2a...male contact, 2b...contact part (silver or gold plated part).

Claims (1)

[Claims] 1. For 1 part by weight of perfluoropolyether,
A surface treatment agent for plating electrical contacts, characterized by containing 0.002 to 0.5 parts by weight of alkyl mercaptan. 2 For 1 part by weight of perfluoropolyether,
Contains 0.002 to 0.5 parts by weight of alkyl mercaptan and further 0.1 to 2.0 parts by weight of oil-soluble fluorosurfactant or ethylene oxide addition of 2,4,7,9-tetramethyl-5-decyne-4,7-diol. 2. The surface treatment agent for plating electrical contacts according to claim 1, wherein the surface treatment agent contains 0.1 to 2.0 parts by weight of a substance.