JP2011113636A - Fitting-in connection terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fitting-in connection terminal capable of controlling deterioration under a high-temperature environment and realizing maintenance of low contact resistance. <P>SOLUTION: The fitting-in connection terminal 10 obtains electrical contact through fitting-in of a male terminal 12 and a female terminal 14. Nickel plating 30 with a hardness of 150-220 Hv is applied to at least one of the contact portions 18a, 18b, 24, 26 by the fitting-in of the male terminal 12 and the female terminal 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fitting-type connection terminal used for electrical connection between an electric circuit and various electric devices in electric wiring of an automobile or the like.

  Conventionally, as a type of connector connection terminal for electrical wiring in automobiles and various electric / electronic devices, for example, as shown in FIG. 1 of Patent Document 1 (Japanese Patent Laid-Open No. 10-302864), a male terminal and a female terminal are connected to each other. A fitting-type connection terminal that is fitted and connected to a conductive state is known. In such a connection terminal, a tin plating layer is generally formed on the surface of a base material made of a copper alloy such as copper or brass. Lid and tin plating have low hardness, and even if an oxide film is formed on the surface, the oxide film is destroyed by friction when the terminals are in contact with each other, the connection between the tin plating layers is maintained, and the low contact resistance is stable It is because it can be demonstrated.

  By the way, in recent years, reflow soldering using lead-free solder that does not use lead has been widely adopted in consideration of the environment. Along with this, the reflow temperature is inevitably higher than the melting point of tin (232 ° C.), and the corrosion resistance of the tin plating film is reduced due to exposure of the mating connection terminal in such a high temperature environment. Problems such as a significant increase in contact resistance have been pointed out.

  Therefore, it is conceivable to form a nickel plating surface film having a high melting point (melting point 1455 ° C.) instead of tin plating for connection terminals exposed to a high temperature environment.

  However, when nickel plating is applied to the joint surface of the mating connection terminal, the contact resistance between the terminals immediately increases, and the required energization performance can be stably maintained. It turned out to be a new problem that was difficult. This problem is particularly noticeable in connection terminals that are installed in a state where vibration is always applied, such as connection terminals for electric wiring mounted on automobiles. Further, contact pressure between male and female terminals under the connection state ( This was more remarkable when the contact force was small.

JP-A-10-302864

  The present invention has been made in the background of the above-mentioned circumstances, and the problem to be solved is that deterioration under a high temperature environment associated with the use of lead-free solder can be suppressed and low contact resistance can be maintained. The object is to provide a fitting type connection terminal.

As a result of intensive studies on the fitting-type connection terminal subjected to nickel plating, the present inventor has found that a significant increase in contact resistance is attributed to the high hardness of nickel plating. That is, the hardness of nickel plating conventionally used for fitting-type connection terminals is as high as 350 Hv to 800 Hv. Therefore, for example, when a mating connection terminal is formed by a combination of nickel plating on the male terminal and tin plating on the female terminal, the nickel plating is applied to the contact portion by the fitting when it slides due to the action of external force such as vibration. It is considered that the tin plating (40 Hv to 80 Hv) having a lower hardness than the above is unilaterally worn and consumed, and an intermetallic compound (Cu ₆ Sn ₅ ) with tin oxide or copper as a base material is generated. These oxides and intermetallic compounds significantly increase the electrical resistance of the contact area. Especially when the contact pressure is low under the condition of constant vibration such as in automobiles, wear due to microsliding with small amplitude is not possible. It has been found that it is more likely to occur and the increase in contact resistance becomes more prominent. The present invention has been completed based on such findings.

  A first aspect of the present invention is a fitting-type connection terminal that obtains electrical contact by fitting a male terminal and a female terminal, and is a contact portion formed by the fitting of at least one of the male terminal and the female terminal. On the other hand, nickel plating having a hardness of 150 Hv to 220 Hv is applied.

  As a result of further investigation by the present inventor based on the above findings, by reducing the hardness of nickel plating to 220 Hv or less, the unidirectional wear and consumption rate of tin plating can be reduced even at the contact portion with tin plating. It has been newly found that the low contact resistance can be stably maintained in the fitting-type connection terminal. Moreover, durability can be ensured by setting the lower limit of the hardness of nickel plating to 150 Hv or more. As a result, nickel plating with a high melting point can be used to suppress deterioration under high-temperature environments, and low contact resistance can be maintained. The contradictory characteristics of high heat resistance and low contact resistance are maintained. For the first time, it has become possible to provide a mating type terminal that is highly compatible with each other.

  According to a second aspect of the present invention, in the first aspect, the base material of the male terminal and the female terminal is copper or a copper alloy, and the male terminal and the female terminal are in sliding contact with each other. The sliding contact portion of the male terminal with respect to the female terminal is subjected to nickel plating having a hardness of 150 Hv to 220 Hv, while the sliding contact portion of the female terminal with respect to the male terminal is Tin plating is applied.

  Between connection terminals that are fitted in sliding contact with each other, sliding is likely to occur at the sliding contact portion. In particular, when one terminal is nickel-plated and the other terminal is tin-plated, the tin plating wears unilaterally due to mutual sliding, and the metal between the tin oxide and the base metal copper It tends to cause a significant increase in contact resistance due to the formation of the compound. In the fitting type connection terminal having such a structure, the unilateral wear of the tin plating of the female terminal during sliding is reduced by applying the nickel plating of the specific hardness according to the present invention to the male terminal. It is possible to maintain low contact resistance effectively.

  According to a third aspect of the present invention, there is provided a connection terminal mounted on a printed circuit board to which reflow soldering of lead-free solder is applied in the first or second aspect.

  According to the connection terminal having a structure according to the present invention, high heat resistance can be obtained by applying nickel plating, so that deterioration can be suppressed even in a high-temperature environment such as a reflow furnace for lead-free solder. Therefore, it can be suitably used for a substrate to which lead-free solder is applied.

  According to a fourth aspect of the present invention, there is provided the apparatus according to any one of the first to third aspects, wherein the fourth aspect is mounted on an automobile and is subjected to vibration.

  As described above, under the condition of constant vibration as in an automobile, the fine sliding wear is likely to occur at the connection portion between the terminals, and the contact resistance is likely to increase remarkably due to the fine sliding wear. By applying nickel plating with a specific hardness according to the present invention to the connection terminals arranged in such a specific situation, the wear of the connection part at the time of fine sliding wear is reduced, and a low contact resistance is effectively achieved. Can be maintained.

  According to the present invention, nickel plating having a hardness of 150 Hv to 220 Hv is applied to the contact portion of at least one of the male terminal and the female terminal of the fitting type connection terminal. By using nickel, high heat resistance can be obtained, and deterioration of plating can be suppressed even in a high temperature environment. At the same time, by setting the hardness of the nickel plating sufficiently low, wear between terminals can be reduced. Thereby, the production | generation of the oxide and intermetallic compound resulting from abrasion can be suppressed, and low contact resistance can be maintained.

Cross-sectional explanatory drawing which shows the fitting type | mold connection terminal as one Embodiment of this invention. Cross-sectional explanatory drawing which shows the contact part with the female terminal in the male terminal shown in FIG. The histogram which shows the frequency distribution of the frequency | count of sliding which reaches a regular contact resistance about an Example and a comparative example. The graph which showed the average value of the frequency | count of sliding which reaches | attains a regulation contact resistance value about an Example and a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, FIG. 1 shows a fitting type connection terminal 10 as an embodiment of the present invention. The fitting-type connection terminal 10 includes a male terminal 12 and a female terminal 14 that are fitted to each other. FIG. 1A shows a non-fitted state, and FIG. 1B shows a fitted state. Indicates.

  The male terminal 12 is formed by bending a conductive metal plate. A tab 16 serving as a fitting portion with the female terminal 14 is provided at the distal end portion of the male terminal 12. The tab 16 has a flat plate shape, and both the surfaces 18a and 18b that are contact portions with the male terminal 14 are flat surfaces. In addition, although illustration is abbreviate | omitted, the wire barrel used as the crimping | compression-bonding part with an electric wire is provided in the other side of the tab 16 in the male terminal 12. FIG.

  On the other hand, the female terminal 14 is formed by bending a conductive metal plate. A fitting portion 20 that fits the male terminal 12 is provided at the distal end portion of the female terminal 14. Moreover, although illustration is abbreviate | omitted, the wire barrel used as the crimping | compression-bonding part with an electric wire is provided in the female terminal 14 on the opposite side to the fitting part 20. FIG. The fitting portion 20 has a hollow box shape having an opening 21. The fitting portion 20 is provided with a tongue piece 22 that protrudes inward of the fitting portion 20 and a bead 24 that faces the tongue piece 22 and protrudes inward of the fitting portion 20.

  The tongue piece 22 is a leaf spring integrally formed with the fitting portion 20 by bending a metal plate forming the female terminal 14. On the surface of the tongue piece 22 that faces the bead 24, an emboss 26 that is a contact portion to the male terminal 16 is formed. The emboss 26 has a spherical shell shape protruding toward the bead 24, and is integrally formed with the tongue piece 22 by pressing or the like.

  On the other hand, the bead 24 is a protrusion that protrudes toward the tongue piece 22 and extends in the fitting direction of the male terminal 12 (left and right direction in FIG. 1), and is integrally formed with the fitting portion 20 by pressing or the like. Has been. The bead 24 is formed in a pair so as to be positioned at both ends of the tab 16 of the male terminal 12 in the direction orthogonal to the fitting direction (left and right direction in FIG. 1), and between the bead 24 and the tongue piece 22. A pair of beads 24 are formed on both sides of the emboss 26 in a facing projection view (a vertical projection view in FIG. 1).

  When fitting the male terminal 12 and the female terminal 14, the tab 16 of the male terminal 12 is inserted into the fitting portion 20 of the female terminal 14 from the opening 21. The tab 16 is inserted between the tongue piece 22 and the bead 24 of the fitting portion 20 to elastically deform the tongue piece 22 in a direction away from the bead 24, and slidably contact the emboss 26 and the bead 24 of the tongue piece 22. While being inserted into the fitting portion 20. As a result, the surface 18a in sliding contact with the emboss 26 and the surface 18b in sliding contact with the bead 24 in the tab 16 are the sliding contact portions with the female terminal 14 in the male terminal 12, while the emboss 26 and bead 24 are in contact with the female terminal. 14 is a sliding contact portion with the male terminal 12.

  The embossing 26 is pressed against the surface 18a of the tab 16 by the elastic restoring force of the tongue piece 22 to exert a contact pressure, and the surface 18b of the tab 16 is pressed against the bead 24 so that the bead 24 receives the contact pressure. The male terminal 12 and the female terminal 14 are fitted and electrically connected. In the fitting state of the male terminal 12 and the female terminal 14, the emboss 26 and the surface 18a of the tab 16 are in a point contact state, while the bead 24 and the surface 18b of the tab 16 are in a line contact state. Thus, the surfaces 18a and 18b of the tab 16 are the contact portions of the male terminal 12 to the female terminal 14, while the emboss 26 and the bead 24 are the contact portions of the female terminal 14 to the male terminal 12.

  Note that the contact pressure at the contact portion between the tab 16 of the male terminal 12 and the emboss 26 and bead 24 of the female terminal 14 is set to 20 N or less, and more preferably 17 N or less. Thereby, the male terminal 12 and the female terminal 14 can be easily fitted with a relatively small insertion force. And even if there is a possibility that fine sliding wear may occur with a small insertion force, low contact resistance can be maintained by applying nickel plating 30 having a specific hardness, which will be described later, to the male terminal 12.

  In such a fitting-type connection terminal 10, the conductive metal plate forming the male terminal 12 has a structure in which a nickel plating 30 is applied to the surface of a base material 28 made of copper or copper alloy, as shown in FIG. The male terminal 12 is formed by bending the conductive metal plate. Thus, nickel plating 30 is applied to the surfaces 18 a and 18 b of the tab 16 of the male terminal 12. The hardness of the nickel plating 30 is set in the range of 150 Hv to 220 Hv. That is, the nickel plating 30 in this embodiment is set to a sufficiently small hardness as compared with the hardness (350 Hv to 800 Hv) of nickel plating conventionally used for fitting-type connection terminals.

  The nickel plating 30 is formed by electrolytic plating that can obtain a low-hardness nickel plating film having a hardness of around 200 Hv. For example, Ni particles are added to a nickel plating bath such as a watt bath, nickel acetate bath, sulfamic acid bath, etc., and a base material 28 is installed on the cathode side, and an electrode metal such as a soluble nickel metal is installed on the anode side. The hardness of the nickel plating 30 can be adjusted by adjusting the bath temperature and current density, the stirring of the solution, the pH of the bath composition, the arrangement conditions of the counter electrode, and the like as the plating conditions.

Specifically, as the bath composition of electrolytic plating, as the pH increases, the hardness of the nickel acetate bath increases approximately linearly, whereas the pH of the Watt bath or sulfamic acid bath exceeds about 5. It is known that the hardness rapidly increases. Further, as the plating condition, the Watts bath, current density hardness becomes lowest at 4A / dm ² about about 8A / dm ² in the nickel acetate bath, hardness is the lowest at about 2A / dm ² in the sulfamic acid bath It is known. Furthermore, as a plating condition, in the Watt bath, the hardness decreases as the bath temperature approaches about 45 ° C. from a low temperature, and a substantially constant low hardness is obtained at a temperature higher than about 45 ° C., whereas nickel acetate In a bath, the hardness is lowest at a bath temperature of about 40 ° C., and in a sulfamic acid bath, a substantially constant low hardness is obtained from a low temperature to about 50 ° C., and when the temperature exceeds about 50 ° C., the hardness increases rapidly. Are known. By appropriately adjusting the bath composition and plating conditions, the nickel plating 30 having a desired hardness can be obtained.

  Further, the thickness t of the nickel plating 30 is not particularly limited, but is preferably set within a range of 0.5 μm to 1.0 μm. Durability can be ensured by setting thickness: t to 0.5 μm or more, and conductive metal coated with nickel plating 30 by setting thickness: t to 1.0 μm or less. The plate can be easily bent.

  On the other hand, the conductive metal plate forming the female terminal 14 has a structure in which tin plating is applied to the surface of a base material made of copper or a copper alloy, as is conventionally known. Thus, tin plating is applied to the emboss 26 and the bead 24 that come into contact with the tab 16 of the male terminal 12.

  The fitting type connection terminal 10 including the male terminal 12 and the female terminal 14 is used as a connector connection terminal or the like in various electric / electronic devices. Although illustration is omitted, in particular, the fitting-type connection terminal 10 in the present embodiment has a male terminal 12 mounted on a printed circuit board subjected to lead-free reflow soldering and connected to a printed circuit board. A tab 16 is projected from the printed circuit board. On the other hand, the female terminal 14 is accommodated in a connector housing or the like to form a mating connector, and the female terminal 14 accommodated in the mating connector is fitted with a tab 16 connected to the printed circuit board. The printed circuit board having the male terminals 12 and the connector having the female terminals 14 are mounted on an automobile as an electric circuit for an automobile and are always provided with vibrations.

  The fitting type connection terminal 10 having such a structure can obtain high heat resistance because the surfaces 18a and 18b of the tab 16 of the male terminal 12 are provided with nickel plating 30 having a high melting point. . Thereby, like this embodiment, it can use suitably also for what is exposed to a high temperature environment like the board | substrate with which reflow soldering by lead-free solder is performed.

  And the nickel plating 30 in this embodiment is set to sufficiently small hardness compared with the conventional nickel plating. As a result, when the tab 16 of the male terminal 12 to which the nickel plating 30 is applied and the embossing 26 or the bead 24 of the female terminal 14 to which the tin plating is applied, the embossing 26 to which the low hardness tin plating is applied and Since the unilateral wear of the bead 24 is reduced and generation of oxides and intermetallic compounds due to wear is suppressed, low contact resistance can be effectively maintained. Accordingly, as in the present embodiment, the contact pressure is relatively low, and the sliding contact is caused between the male terminal 12 and the female terminal 14 by being arranged in a state where the vibration is constantly applied like an automobile. Even if it is easy, low contact resistance can be maintained for a longer period of time. Further, when the male terminal 12 and the female terminal 14 are fitted, the emboss 26 is slidably brought into contact with the tab 16 and fitted while scraping the nickel plating 30 of the tab 16, whereby the emboss 26 is formed in the nickel plating 30. It will be in a state of being fitted in. Thereby, the fine sliding wear itself between the tab 16 and the emboss 26 can also be suppressed.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited by the specific description. For example, in the embodiment, the nickel plating 30 may be applied to the emboss 26 and the bead 24 of the female terminal 14, while the tab 16 of the male terminal 12 may be tin-plated, or both the male terminal 12 and the female terminal 14 may be applied. Nickel plating 30 may be applied to the contact portion. Moreover, the nickel plating should just be formed in the contact part of a terminal at least, for example, only the surface 18a, 18b of the tab 16 of the male terminal 12 in the said embodiment, the embossing 26 of the female terminal 14, and the bead 24 only. The nickel plating 30 may be applied to the male terminal 12 and the female terminal 14, and a portion such as a wire barrel other than the contact portion may be subjected to tin plating.

  In addition, the specific shape and application examples of the fitting type connection terminal 10 in the above embodiment are merely examples, and for example, the male terminal is a tab of a bus bar used as an internal circuit of an electric connection box of an automobile. Alternatively, it may be a linear terminal having a rectangular cross section or a tab-shaped terminal having a flat cross section, which is used as a terminal of a board connector and protrudes on the board. Further, the present invention is not limited to the fitting type connection terminal used in the electric circuit of the automobile, and can be widely used in the fitting type connection terminal used in various electric devices.

  Next, in order to verify the effectiveness of the present invention, the results of comparison and examination of an example according to the present invention and a comparative example according to the conventional structure are shown below.

  First, as an example, it consists of a male terminal having a width of 2.3 mm × thickness of 0.64 mm plated with nickel having a hardness of 220 Hv according to the present invention and a female terminal plated with tin for the male terminal. 5 fitting type connection terminals set to 8N were prepared. Further, as a comparative example, it consists of a male terminal having the same shape as that of the example plated with nickel of hardness 370 Hv according to the conventional structure, and a female terminal having the same shape as the example plated with tin, and the terminal indirect point is equal to the example. Five fitting-type connection terminals having a pressure set to 8N were prepared. That is, the comparative example is different from the example only in that the plating applied to the male terminal is a high-hardness nickel plating according to the conventional structure.

  Then, a contact point resistance value monitor was attached to each of the five test bodies of these examples and comparative examples, and a fine sliding test was repeated in which fine sliding was repeated between the male terminal and the female terminal. The sliding distance was 200 μm, and the energization conditions were 20 mV and 10 mA / DC.

  Table 1 shows the number of sliding times that reached a predetermined contact resistance increase value (3 mΩ, 6 mΩ, 10 mΩ) for each of the five test specimens of Examples and Comparative Examples, and Table 2 shows the results of Table 1 in frequency. Shown as distribution. Moreover, the histogram of Table 2 is shown to FIG. 3 (a) and FIG.3 (b) about each of an Example and a comparative example, respectively. The value of “sliding frequency” on the horizontal axis in FIG. 3 is the value of “class value (sliding frequency)” in Table 2. For example, “1500” of “sliding frequency” in FIG. This is representative of the range of the number of movements from 1 to 3000.

  As is apparent from FIG. 3, in the comparative example, all the test specimens have a sliding frequency of “4500” (sliding frequency of 3001 to 6000 times), and the contact resistance increases to 3 mΩ. On the other hand, in the examples, there is a test body in which the increase in contact resistance has not yet reached 3 mΩ within the range of the same number of sliding times. Further, in the comparative example, the increase in contact resistance reached 10 mΩ for all the test specimens before the number of sliding exceeded “10500” (sliding number 9001 to 12000), whereas in the example, the same sliding There is a test body whose contact resistance has not yet increased to 10 mΩ by the number of times.

  FIG. 4 is a graph showing the average values of the examples and comparative examples shown in Table 1. FIG. 4 also shows that according to the example, the number of sliding times reaching the same specified contact resistance increase value as in the comparative example is much larger than in the comparative example. Further, as the specified contact resistance increase value increases, the difference in the number of sliding operations between the example and the comparative example is further increased. From these test results, according to the present invention, it was confirmed that the rapid increase of the contact resistance can be suppressed and the low contact resistance can be more effectively maintained.

10: mating connection terminal, 12: male terminal, 14: female terminal, 16: tab, 18a, b: surface (contact part), 24: bead (contact part), 26: emboss (contact part), 28: Base material, 30: Nickel plating

Claims (4)

A fitting type connection terminal that obtains electrical contact by fitting a male terminal and a female terminal,
A fitting-type connection terminal, wherein a nickel plating having a hardness of 150 Hv to 220 Hv is applied to a contact portion of the male terminal and the female terminal by the fitting.   The base material of the male terminal and the female terminal is copper or a copper alloy, and the male terminal and the female terminal are in sliding contact with each other, and the sliding contact portion of the male terminal with respect to the female terminal The fitting type connection terminal according to claim 1, wherein nickel plating having a hardness of 150Hv to 220Hv is applied, and a tin contact is applied to a sliding contact portion of the female terminal with respect to the male terminal.   The fitting type connection terminal according to claim 1, wherein the connection type connection terminal is mounted on a printed circuit board to which reflow soldering of lead-free solder is applied.   The fitting type connection terminal according to any one of claims 1 to 3, wherein the fitting type connection terminal is disposed in a state of being mounted on an automobile and subjected to vibration.

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