Anti-corrosion terminal material, anti-corrosion terminal and electric wire end structure

Abstract

An anti-corrosion terminal material including a base material made of copper or copper alloy and a coating film laminated on the base material: the coating film includes: a first coating film, provided with a zinc layer made of zinc alloy and a tin layer made of tin or tin alloy which are laminated in this order, and formed at a planned core contact part; and a second coating film including the tin layer but not comprising the zinc layer, which is provided at a planned contact part being a contact part when the terminal is formed: and the zinc layer has a thickness not less than 0.1 μm and not more than 5.0 μm and zinc concentration not less than 30% by mass and not more than 95% by mass, and has any one or more of nickel, iron, manganese, molybdenum, cobalt, cadmium, lead and tin as a balance.

Claims

1. An anti-corrosion terminal material comprising a base material made of copper or copper alloy and a coating film laminated on the base material, wherein the coating film comprises: a first coating film formed on a surface of a planned core contact part in which a core of an electric wire is in contact with when a terminal is formed and having a zinc layer made of zinc alloy and a tin layer made of tin or tin alloy which are laminated in this order; and a second coating film formed on a surface of the part except for a planned core contact comprising a tin layer, of the second coating film, made of tin or tin alloy but not comprising a zinc layer, and wherein the zinc layer, of the first coating film, has a thickness not less than 0.1 μm and not more than 5.0 μm and zinc concentration not less than 30% by mass and not more than 95% by mass, and has any one or more of nickel, iron, manganese, molybdenum, cobalt, cadmium, lead and tin as a balance.

2. The anti-corrosion terminal material according to claim 1, wherein a proportion of an area of the zinc layer, of the first coating film, to a surface after the terminal is formed is not less than 30% and not more than 80%.

3. The anti-corrosion terminal material according to claim 1, wherein a mean crystal grain size of tin or tin alloy in the tin layer of the first coating film is not less than 0.5 and not more than 8.0 μm.

4. The anti-corrosion terminal material according to claim 1, wherein at the planned core contact part, the tin layer of the first coating film has a thickness not less than 0.8 and not more than 6.0 μm and made of tin alloy having zinc concentration not less than 0.4% by mass and not more than 15% by mass.

5. The anti-corrosion terminal material according to claim 1, wherein an undercoat layer made of nickel or nickel alloy is provided between the base material and the coating film.

6. The anti-corrosion terminal material according to claim 1, comprising a carrier part having a belt-shape; and terminal members connected with an interval therebetween along a length direction of the carrier part and provided with the planned core contact part and the planned contact part.

7. An anti-corrosion terminal formed of the anti-corrosion terminal material according to claim 1.

8. An electric wire end structure wherein the anti-corrosion terminal according to claim 7 is crimped to an end of an electric wire formed of aluminum wire material made of aluminum or aluminum alloy.

9. The anti-corrosion terminal material according to claim 1, wherein the thickness of the zinc layer, of the first coating film, is not less than 0.3 μm and not more than 2.0 μm.

10. The anti-corrosion terminal material according to claim 1, wherein the zinc concentration of the zinc layer, of the first coating film, is not less than 65% by mass.

11. The anti-corrosion terminal material according to claim 1, wherein a total of any one or more of nickel, iron, manganese, molybdenum, cobalt, cadmium, lead and tin contained in the zinc layer, of the first coating film, is not less than 5% by mass.

12. The anti-corrosion terminal material according to claim 3, wherein a mean crystal grain size of tin or tin alloy in the tin layer, of the first coating film, is not less than 1.2 and not more than 3.0 μm.

13. The anti-corrosion terminal material according to claim 4, wherein the zinc concentration in the tin layer, of the first coating film, is not less than 0.6% by mas and not more than 6.0% by mass.

14. The anti-corrosion terminal material according to claim 5, wherein the zinc concentration in the tin layer, of the first coating film, is not less than 0.6% by mas and not more than 6.0% by mass.

15. The anti-corrosion terminal material according to claim 5, wherein a thickness of the undercoat layer is not less than 0.1 μm and not more than 5.0 μm.

16. The anti-corrosion terminal material according to claim 15, wherein a thickness of the undercoat layer is not less than 0.3 μm and not more than 2.0 μm.

17. The anti-corrosion terminal material according to claim 5, wherein a nickel content percentage in the undercoat layer is not less than 80% by mass.

18. The anti-corrosion terminal material according to claim 17, wherein the nickel content percentage is not less than 90% by mass.

19. The anti-corrosion terminal according to claim 7, provided with: a core-crimping part to which a core of an electric wire is crimped, a cover-crimping part to which a cover part of the electric wire is crimped, and a coupling part to which another terminal is connected.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 It is a cross sectional view of an essential part schematically showing an anti-corrosion terminal material according to an embodiment of the present invention.

(2) FIG. 2 It is a plan view of the anti-corrosion terminal material of the embodiment.

(3) FIG. 3 It is a perspective view showing an example of an anti-corrosion terminal on which the anti-corrosion terminal material of the embodiment is applied.

(4) FIG. 4 It is a frontal view showing an electric wire end structure in which the anti-corrosion terminal of FIG. 3 is crimped to an end part of an electric wire.

(5) FIG. 5 It is a cross sectional view of an essential part schematically showing another embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

(6) An anti-corrosion terminal material, an anti-corrosion terminal and an electric wire end structure according to an embodiment of the present invention will be explained.

(7) An anti-corrosion terminal material 1 of the present embodiment is, as entirely shown in FIG. 2, a strip material formed in a belt-shape for forming terminals: between a pair of belt-shaped carrier parts 21 extending in a parallel manner, terminal members 22 to be formed into terminals are disposed with intervals in a longitudinal direction of the carrier parts 21; the respective terminal members 22 are connected to both the carrier parts 21 with narrow connecting parts 23 therebetween. The terminal members 22 are formed to have a shape shown in FIG. 3 for instance, and finished as anti-corrosion terminals 10 (refer to FIG. 4) by being cut off from the connecting parts 23.

(8) In the anti-corrosion terminal material 10 (an example in FIG. 3 is a female terminal), a coupling part 11 to which a male terminal 15 (refer to FIG. 4) is fit-inserted, a core-crimping part 13 to which an exposed core (an aluminum wire material) 12a of an electric wire 12 is crimped, and a cover-crimping part 14 to which a cover part 12b of the electric wire 12 is crimped are arranged in this order from a tip and formed integrally. The coupling part 11 is formed into a square tube shape: a spring tab 11a which is connected to a tip of the coupling part 11 is inserted inside the coupling part 11 so as to be folded (refer to FIG. 4).

(9) FIG. 4 shows a terminal end part structure in which the anti-corrosion terminal 10 is crimped to the electric wire 12. In this electric wire end structure, the vicinity of the core-crimping part 13 is directly in contact with the core 12a of the electric wire 12.

(10) In the strip material shown in FIG. 2, when it is formed into the anti-corrosion terminals 10, a part which will be a contact which forms the coupling part 11 and will be in contact with the male terminal 15 is a planned contact part 25, and a surface of a part with which the core 12a is in contact in the vicinity of the core crimping part 13 is a planned core contact part 26.

(11) In this case, when the female terminal 10 of the embodiment is formed, the planned contact parts 25 are an inner surface of the coupling part 11 formed into the square tube shape and a surface facing to the spring tab 11a folded inside the coupling part 11. In a state in which the coupling part 11 is expanded as shown in FIG. 2, surfaces at both sides of the coupling part 11 and a back surface of the spring tab 11a are the planned contact parts 25.

(12) In the anti-corrosion terminal material 1, as FIG. 1 schematically showing a cross section (corresponding to a cross section taken along the line A-A in FIG. 2), a coating film 8 is formed on a base material 2 made of copper or copper alloy, and an undercoat layer 3 made of nickel or nickel alloy is formed between the base material 2 and the coating film 8.

(13) The coating film 8 is consist of a first coating film 81 formed on a surface of the planned core contact part 26 and a second coating film 82 formed on surface of parts except for the planned core contact part 26. In the first coating film 81, a zinc layer 4 made of zinc alloy and a tin layer 5 made of tin or tin alloy are laminated in this order on the base material 2.

(14) In the second coating film 82 formed on the surface of the planned contact parts 25, only the tin layer 5 is laminated but the zinc layer 4 is not provided. It is preferable for the zinc layer 4 to exist with an area proportion not less than 30% and not more than 80% of a surface of the terminal 10 after forming (a surface of the terminal member 22).

(15) The base material 2 is not specifically limited in a composition thereof, if it is made of copper or copper alloy.

(16) The undercoat layer 3 has a thickness not less than 0.1 μm and not more than 5.0 μm and a nickel content percentage not less than 80% by mass. The undercoat layer 3 has a function of preventing diffusion of copper from the base material 2 to the zinc layer 4 and the tin layer 5. If the thickness of the undercoat layer 3 is less than 0.1 μm, an effect of preventing the diffusion of copper is poor: if it is more than 5.0 μm, breakages are easy to occur while press machining. The thickness of the undercoat layer 3 is more preferably not less than 0.3 μm and not more than 2.0 μm.

(17) If the nickel content percentage is less than 80% by mass, the effect of preventing the diffusion of copper to the zinc layer 4 and the tin layer 5 is poor. The nickel content percentage is more preferably not less than 90% by mass.

(18) Next, the first coating film 81 formed on the surface of the parts excluding the planned contact parts 25 (parts including the planned core contact part 26) will be explained.

(19) As described above, the first coating film 81 is formed by laminating the zinc layer 4 and the tin layer 5, and zinc in the zinc layer 4 is diffused in the tin layer 5. Therefore, the tin layer 5 of the first coating film 81 has a corrosion potential near to that of aluminum, so it is possible to prevent the corrosion when it is in contact with the aluminum wire material.

(20) The zinc layer 4 has a thickness not less than 0.1 μm and not more than 5.0 μm and is made of zinc alloy containing zinc. The zinc layer 4 contains a zinc with a concentration not less than 30% by mass and not more than 95% by mass, and a balance including one or more of nickel, iron, manganese, molybdenum, cobalt, cadmium, lead and tin.

(21) Nickel, iron, manganese, molybdenum, cobalt, cadmium, lead and tin are preferable to improve an anti-corrosion property of the zinc layer 4 itself: by forming the zinc layer 4 from zinc alloy containing one or more of these, it is possible to maintain the zinc layer for long term even when the tin layer 5 is lost by being exposed in excessive corrosive environment, and the corrosion current can be prevented from increasing.

(22) In addition, nickel zinc alloy and tin zinc alloy has high effect of improving the anti-corrosion property of the zinc layer 4: it is especially preferable that the zinc layer 4 be made of zinc alloy containing one or more of nickel or tin. As described above, the zinc concentration of the zinc layer 4 is not less than 30% by mass and not more than 95% by mass: additives consisting of any one or more of nickel, iron, manganese, molybdenum, cobalt, cadmium, lead, and tin is contained with not less than 5% by mass in the zinc layer 4.

(23) If the zinc concentration of the zinc layer 4 is less than 30% by mass, the anti-corrosion property of the zinc layer 4 is deteriorated; and the zinc layer 4 is corroded and lost rapidly and the base material 2 is exposed if the zinc layer 4 is exposed in the corrosive environment such as salt water, so it is easy to be corroded with the core (the aluminum wire material) 12a. The zinc concentration of the zinc layer 4 is more preferably not less than 65% by mass. By contrast, if the zinc concentration of the zinc layer 4 is more than 95% by mass, zinc is excessively diffused to the tin layer 5, so that the contact resistance between the core 12a and the terminal 10 is increased.

(24) If the thickness of the zinc layer 4 is less than 0.1 μm, the effect of lowering the corrosion potential at the surface of the first coating film 81 (the tin layer 5) is poor: if it is more than 5.0 μm, press machinability is deteriorated and the breakages may occur when the press machining into the terminals 10 is performed. It is more preferable that the thickness of the zinc layer 4 be not less than 0.3 μm and not more than 2.0 μm.

(25) The tin layer 5 of the first coating film 81 has a zinc concentration not less than 0.4% by mass and not more than 15% by mass. As described above, if the tin layer 5 of the first coating film 81 contains zinc, there is an effect of preventing corrosion of the core 12a made of aluminum by lowering the corrosion potential: however, if the zinc concentration of the tin layer 5 is less than 0.4% by mass, the effect of preventing the corrosion of the core 12a by lowering the corrosion potential is poor; and if it is more than 15% by mass, the anti-corrosion property of the tin layer 5 is remarkably deteriorated and the tin layer 5 is corroded by being exposed in the corrosion environment, and the contact resistance between the first coating film 81 and the core 12a may be deteriorated. It is preferable for the tin layer 5 of the first coating film 81 that the zinc concentration be not less than 0.6% by mass and not more than 6.0% by mass in a case in which the thickness is not less than 0.8 μm and not more than 6.0 μm.

(26) It is preferable that the thickness of the tin layer 5 of the first coating film 81 be not less than 0.8 μm and not more than 6.0 μm. If the thickness of the tin layer 5 is less than 0.8 μm, the thickness of the tin layer 5 is too thin, so that solder wettability is deteriorated and it may cause deterioration of the contact resistance. By contrast, if the thickness of the tin layer 5 is more than 6.0 μm, the thickness of the tin layer 5 is too thick, so it may cause increase of dynamic friction coefficient on a surface of the first coating film 81, and mount/dismount resistance is tend to be large at the planned core contact part 26 for use as a connector or the like.

(27) It is preferable that a mean crystal grain size of tin or tin alloy in the tin layer 5 of the first coating film 81 be not less than 0.5 μm and not more than 8.0 μm; specially, not less than 1.2 μm and not more than 3.0 μm. Zinc in the tin layer 5 of the first coating film 81 is dispersed (diffused) into the tin layer 5 from the zinc layer 4 through tin-crystal grain boundaries: if the mean crystal grain size of tin or tin alloy in the tin layer 5 is minute (the mean crystal grain size is not less than 0.5 μm and not more than 8.0 μm), a diffusion amount of zinc is increased and the anti-corrosion effect can be increased. Moreover, since zinc is continuously supplied even when being exposed in the corrosive environment and the zinc concentration in the tin layer 5 is decreased, durability of the anti-corrosion effect can be improved.

(28) If the mean crystal grain size of tin or tin alloy in the tin layer 5 is less than 0.5 μm, a density of grain boundaries is too high and the diffusion of zinc is excessive, and the anti-corrosion property of the tin layer 5 is deteriorated. Accordingly, the tin layer 5 is corroded when exposed in the corrosion environment, and the contact resistance with the core 12a may be deteriorated (increased). By contrast, if the mean crystal grain size of tin or tin alloy in the tin layer 5 is more than 8.0 μm, the diffusion of zinc is not enough, and the effect of preventing the core 12a from corrosion may be poor.

(29) The first coating film 81 having the above layered structure exists on a surface of parts except for the planned contact parts 25 as described above. As described above, it is necessary for the first coating film 81 having the zinc layer 4 to exist on the planned core contact parts 26 which are in contact with the core 12a made of aluminum: however, the zinc layer 4 is not necessary to exist on the other parts. Nevertheless, it is preferable that a proportion of parts in which the zinc layer 4 exists be higher since corrosion current flows from separated parts in galvanic corrosion (contact corrosion between dissimilar metals): it is preferable that the zinc layer 4 exists at an area proportion not less than 30% and not more than 80% of an entire surface when it is formed as the terminal 10.

(30) In the second coating film 82 formed on the planned contact parts 25, only the tin layer 5 exists but the zinc layer 4 is not included. If zinc exists on a surface of the tin layer 5 of the second coating film 82, corrosion products of zinc are piled up under high-temperature and high-humidity environment, the connection reliability as a contact may be deteriorated. Accordingly, by a structure of not having the zinc layer 4 on the second coating film 82 of the planned contact part 25, it is possible to prevent the increase of the contact resistance even when it is exposed in the high-temperature and high-humidity environment. In addition, composition, a film thickness and the like of the undercoat layer 3 provided between the base material 2 and the second coating film 82 are the same as those forming the undercoat layer 3 formed between the base material 2 and the first coating film 81 existing on the surface of the parts except for the planned contact part 25.

(31) Although the tin layer 5 of the first coating film 81 and the second coating film 82 is most preferably pure tin; it may be tin alloy containing zinc, nickel, copper and the like is applicable.

(32) In addition, on the surface of the first coating film 81 and the second coating film 82, i.e., on the surface of the tin layer 5, an oxide layer of zinc or tin is generated.

(33) Next, a method of manufacturing the anti-corrosion terminal material 1 will be explained.

(34) As the base material 2, a board material made of copper or copper alloy is prepared. By performing machining of cutting, drilling and the like, a strip material in which the terminal members 22 are connected to the carrier parts 21 by the connecting parts 23 is formed as shown in FIG. 2.

(35) After cleaning the surface by performing degreasing, pickling and the like on the strip material, then nickel or nickel alloy plating is performed on the entire surface for forming the undercoat layer 3. After that, the planned contact parts 25 are covered by masks (not illustrated); zinc alloy plating for forming the zinc layer 4 is performed in the state; the masks are removed; and performed is tin or tin alloy plating for forming the tin layer 5 on the entire surface.

(36) The nickel or nickel alloy plating for forming the undercoat layer 3 on the surface of the base material 2 is not specifically limited if a dense film mainly made of nickel can be obtained: it can be formed by electroplating using a known Watt bath, a sulfamic acid bath, a citric acid bath, and the like. For the nickel alloy plating, nickel tungsten alloy (Ni—W), nickel phosphorus alloy (Ni—P), nickel cobalt alloy (Ni—Co), nickel chromium alloy (Ni—Cr), nickel iron alloy (NiFe), nickel zinc alloy (Ni—Zn), nickel boron alloy (Ni—B) and the like can be used.

(37) Considering the press bendability of the anti-corrosion terminal 10 and the barrier property against copper, pure nickel plating which can be obtained by the sulfamic acid bath is desirable.

(38) The method of forming the zinc layer 4 is not specifically limited; nevertheless, it is preferable to use an electroplating method from a viewpoint of productivity. The zinc alloy plating is not specifically limited if a dense film can be obtained with a desired composition; a known sulfate bath, a chloride bath, a zincate bath or the like can be used. For zinc alloy plating, a complexing agent bath containing citric acid can be used for zinc tin alloy plating; a sulfate bath, a chloride bath, an alkaline bath can be used for zinc nickel alloy plating; a sulfate bath can be used for zinc cobalt alloy plating; a chloride bath containing citric acid can be used for zinc manganese alloy plating; and a chloride bath can be used for zinc molybdenum plating: thereby a film can be formed. Although illustration is omitted, the planned contact parts 25 are covered by a mask such as a masking tape, the parts except for the planned contact parts 25 are plated. Other than plating methods, an evaporation method can be used.

(39) Tin or tin alloy plating for forming the tin layer 5 can be performed by known methods: nevertheless, in order to control the mean crystal grain size of tin or tin alloy in the tin layer 5 to be an optimal value, the electroplating can be performed by using an acid bath, for example, such as an organic acid bath (e.g., a phenol sulfonic acid bath, an alkane sulfonic acid bath or an alkanol-sulfonic acid bath), a fluoroboric bath, a halogen bath, a sulfate bath, a pyrophosphoric acid bath or the like, or an alkaline bath such as a potassium bath, a sodium bath or the like. Although omitting to illustrate, tin or tin alloy plating is performed on the entire surface including the planned contact parts 25 and the planned core contact parts 26 with removing the masks on the planned contact parts 25.

(40) In order to control the mean crystal grain size of tin or tin alloy in the tin layer 5 to not more than 0.8 μm, preferably, as additives reducing the mean crystal grain size, added are: aldehydes such as formaldehyde, benzaldehyde, naphthaldehyde and the like, unsaturated hydrocarbon compounds such as methacrylic acid, acrylic acid, and the like.

(41) In order to advance mutual diffusion between the zinc layer 4 and the tin layer 5 at normal temperature (25° C.), it is important to pile a tin plating layer after cleaning a surface of a zinc plating layer. Since hydroxide oxide and oxide are rapidly generated on the surface of the zinc plating layer: to continuously form films by plating, it is preferable to cleanse it by sodium hydroxide aqueous solution or ammonium chloride aqueous solution to remove hydroxide and oxide and immediately form a film of the tin plating layer. In addition, when forming the tin layer by a dry method such as the evaporation, it is preferable to etch the surface of the zinc layer by argon sputtering before forming the tin layer.

(42) As above mentioned, carried out are nickel or nickel alloy plating, zinc alloy plating and tin or tin alloy plating on the base material 2 in this order, then a heat treatment is carried out.

(43) In this heat treatment, material is heated at temperature in which a surface temperature be not less than 30° C. and not more than 190° C. By this heat treatment, zinc in the zinc plating layer is diffused into the tin plating layer and on the tin plating layer at parts except for the planned contact parts 25. Since zinc is diffused immediately, it is preferable to be exposed at temperature not less than 30° C. for 24 hours or longer. Nevertheless, it is not heated to temperature higher than 190° C., because zinc alloy repels melted tin and tin-repelled parts are generated on the tin layer 5. Moreover, if it is exposed for long time at higher than 160° C., contrarily tin is diffused to the zinc layer 4, so that zinc may be impeded to be diffused to the tin layer 5. Accordingly, more preferable condition is the heating temperature not less than 30° C. and not more than 160° C. and the heating time not less than 30 minutes and not more than 60 minutes.

(44) In the anti-corrosion terminal material 1 manufactured as above, overall, the undercoat layer 3 made of nickel or nickel alloy is formed on the base material 2, the tin layer 5 is formed on the undercoat layer 3 at the planned contact parts 25 previously covered by the mask, and the zinc layer 4 and the tin layer 5 are formed on the undercoat layer 3 at the parts except for the planned contact parts 25. Moreover, an oxide layer is thinly generated on the surface of the tin layer 5 of these films 8.

(45) Then, the shape of the terminal shown in FIG. 3 is formed as it is the strip material by pressing or the like, and the connecting parts 23 are cut off so as to form into the anti-corrosion terminal 10.

(46) FIG. 4 shows the end part structure in which the anti-corrosion terminal 10 is crimped on the electric wire 12; the vicinity of the core-crimping part 13 is directly in contact with the core 12a of the electric wire 12.

(47) In this anti-corrosion terminal 10, since the tin layer 5 contains zinc having the nearer corrosion potential to that of aluminum than that of tin on the planned core contact parts 26, the corrosion potential of the tin layer 5 at the planned core contact parts 26 is near to that of aluminum. Accordingly, the effect of preventing corrosion of the core (aluminum wire material) 12a made of aluminum is high, so that it is possible to effectively prevent the contact corrosion between dissimilar metals, even in a state in which the planned core contact part 25 is crimped to the core 12a. In this case, since the plating and heat treatment were carried out in the state of the strip material in FIG. 2, the base material 2 is scarcely exposed except for small parts which were connected by the connecting parts 23 in end surfaces of the anti-corrosion terminal 10: accordingly, excellent corrosion-resistant effect can be shown.

(48) Moreover, even if the tin layer 5 is entirely or partly disappeared by abrasion or the like, since the zinc layer 4 is formed under the tin layer 5, and since the zinc layer 4 has the corrosion potential near to that of aluminum, the contact corrosion of dissimilar metals can be certainly prevented from occurrence.

(49) Meanwhile, on the second coating film 82 of the planned contact parts 25, it is possible to restrict the contact resistance from rising even when exposed in the high-temperature and high-humidity environment, since the zinc layer 4 is not provided under the tin layer 5.

(50) The present invention is not limited to the above-described embodiment and various modifications may be made without departing from the scope of the present invention.

(51) For example, in the above embodiment, the method not forming the zinc layer 4 on the planned contact parts 25 was applied, as carrying out zinc alloy plating while covering the planned contact parts 25 by the mask in the embodiment: however, a method is also applicable that zinc alloy plating is carried out on an entire surface including the planned contact parts 25, and the zinc alloy plating layer on the planned contact parts 25 is removed by partial etching.

(52) In the former embodiment, the outermost surface of the coating film 8 is formed of the tin layer 5: however, as shown in FIG. 5, a surface metal-zinc layer 6 may be formed on the tin layer 5 at parts except for the planned contact parts 25. The surface metal-zinc layer 6 is a layer formed on the surface of the tin layer 5 by diffusing zinc in the zinc alloy plating layer to the surface through the tin plating layer in the above-described heat treatment; it is different from the zinc layer 4 provided under the tin layer 5 and forming the first coating film 81. Accordingly, in the above-described area proportion of the zinc layer 4, a proportion of an area of this surface metal-zinc layer 6 is not included. Since the surface of the first coating film 81 is formed from the surface metal-zinc layer 6, it is reliably prevent the corrosion by the contact with the core 12a made of aluminum. In addition, an oxide layer 7 is generated thinly on the surface metal-zinc layer 6.

(53) Besides the surface metal-zinc layer 6 is formed by diffusion from the zinc alloy plating layer, it can be formed by carrying out zinc plating on the surface of the tin layer 5. This zinc plating can be carried out by electroplating using known methods: for example, a zincate bath, a sulfate bath, a zinc chloride bath, and a cyanogen bath.

EXAMPLES

(54) A copper board of C1020 was used as the base material; the strip material shown in FIG. 2 was punched out from this copper board, degreased and pickled, and nickel plated in a case of forming the undercoat layer was formed; and then zinc alloy plating was carried out except for the planned contact parts 25 in FIG. 2. Furthermore, after that, tin plating was carried out on the entire surface. Then, the heat treatment was carried out for this copper board with plating layers at temperature 30° C. to 190° C. for not less than 1 hour and not more than 36 hours, so that Samples 1 to 16 of the anti-corrosion terminal material shown in Table 1 were obtained.

(55) Comparative Examples were manufactured as follows: for Sample 18, a zinc layer was formed at short time and low current density when zinc plating was carried out on the planned core contact part: for Sample 19, the zinc layer was formed on the planned contact part by carrying out zinc plating on the entire surface without covering the planned contact part: and for Sample 17, though zinc plating was not carried out either on parts the other than the planned contact part, after degreasing and pickling on the copper board, nickel plating and tin plating were carried out in order.

(56) Principal plating conditions were as follows: the zinc concentration (zinc content percentage) of the zinc layer was adjusted by varying a ratio between zinc ions and additive metal element ions in plating solution. In addition, the content amounts of the additive metal elements were denoted by proportions (% by mass) in parentheses in final columns of the respective additive metal elements in TABLE 1.

(57) The following zinc nickel alloy plating condition is an example in which the nickel content percentage is 15% by mass. In addition, nickel plating for the undercoat layer 3 was not carried out on Samples 1 to 13 and 17 to 19; on Samples 14 to 16, nickel plating was carried out so that the undercoat layer 3 was formed.

(58) —Nickel Plating Condition—

(59) Composition of Plating Bath

(60) Nickel sulfamate: 300 g/L

(61) Nickel chloride: 5 g/L

(62) Boric acid: 30 g/L

(63) Bath Temperature: 45° C.

(64) Current Density: 5 A/dm.sup.2

(65) —Zinc Plating Condition—

(66) Composition of Plating Bath

(67) Zinc sulfate heptahydrate: 250 g/L

(68) Sodium sulfate: 150 g/L

(69) pH=1.2

(70) Bathe Temperature: 45° C.

(71) Current Density: 5 A/dm.sup.2

(72) —Zinc Nickel Alloy Plating Condition—

(73) Composition of Plating Bath

(74) Zinc sulfate heptahydrate: 75 g/L

(75) Nickel sulfate hexahydrate: 180 g/L

(76) Sodium sulfate: 140 g/L

(77) pH=2.0

(78) Bath Temperature: 45° C.

(79) Current Density: 5 A/dm.sup.2

(80) —Condition of Tin Zinc Alloy Plating—

(81) Composition of Plating Bath

(82) Tin(II) sulfate: 40 g/L

(83) Zinc sulfate heptahydrate: 5 g/L

(84) Trisodium citrate: 65 g/L

(85) Nonionic surfactant: 1 g/L

(86) pH=5.0

(87) Bath Temperature: 25° C.

(88) Current Density: 3 A/dm.sup.2

(89) —Zinc Manganese Alloy Plating Condition—

(90) Composition of Plating Bath

(91) Manganese sulfate monohydrate: 110 g/L

(92) Zinc sulfate heptahydrate: 50 g/L

(93) Trisodium citrate: 250 g/L

(94) pH=5.3

(95) Bath Temperature: 30° C.

(96) Current Density: 5 A/dm.sup.2

(97) —Zinc Molybdenum Alloy Plating Condition—

(98) Composition of Plating Bath

(99) Hexaammonium heptamolybdate tetrahydrate: 1 g/L

(100) Zinc sulfate heptahydrate: 250 g/L

(101) Trisodium citrate: 250 g/L

(102) pH=5.3

(103) Bath Temperature: 30° C.

(104) Current Density: 5 A/dm.sup.2

(105) —Tin Plating Condition—

(106) Composition of Plating Bath

(107) Stannous methanesulfonate: 200 g/L

(108) Methanesulfonic acid: 100 g/L

(109) Gloss Agent

(110) Bath Temperature: 25° C.

(111) Current Density: 5 A/dm.sup.2

(112) As to the resulting Samples, respective thicknesses of the zinc layer and the tin layer, zinc concentration in the zinc layer and the tin layer, a mean crystal grain size of the tin layer and the area proportion of the zinc layer were measured.

(113) The thickness of the zinc layer was measured by observing a cross section by a scanning ion microscope. The zinc concentration of the zinc layer was measured as follows: an observation piece with a thickness not more than 100 nm was formed, using a focused ion beam device made by Seiko Instrument Inc. (FIB: model No. SMI3050 TB): the observation piece was observed by a scanning transmission electron microscope made by JEOL Ltd. (STEM: model No. JEM-2010F) at an acceleration voltage 200 kV; and measured using an energy dispersive X-ray spectrometer (EDS made by Thermo) belonging to the STEM. The zinc concentration was obtained as a mean value of values measured at 5 points at even intervals in a film thickness direction.

(114) The zinc concentration in the tin layer was measured at a surface of the sample using an electron probe micro analyzer (EPMA: model No. JXA-8530F) made by JEOL Ltd., at an acceleration voltage 6.5 kV and a beam diameter 30 μm.

(115) As to the mean crystal grain size of tin and tin alloy in the tin layer, obtained as follows: cut-surface machining was carried out by the focused ion beam (FIB), a line was drawn with a length 5 μm parallel to the surface using a measured image of a scanning ion microscope (SIM), and it was found by linear analysis using a number at which the line crosses to crystal boundaries.

(116) TABLE-US-00001 TABLE 1 PLANNED CORE CONTACT PART PLANNED TIN LAYER CONTACT PART ZINC MEAN ZINC LAYER TIN LAYER LAYER UNDER- CRYSTAL ZINC ZINC ADDITIVE ZINC AREA COAT GRAIN CONCEN- THICK- CONCEN- THICK- METAL CONCEN- ZINC PRO- SAMPLE LAYER SIZE TRATION NESS TRATION NESS ELEMENT TRATION LAYER PORTION No. EXISTENCE (μM) (% by mass) (μM) (% by mass) (μM) (% by mass) (% by mass) EXISTENCE (%) 1 NO 8.5 0.3 0.5 30 5.0 Co(70) 0 NO 10 2 NO 0.4 25.0 0.6 95 0.1 Ni(5) 0 NO 27 3 NO 0.4 20.0 7.0 90 0.3 Fe(10) 0 NO 22 4 NO 0.4 0.2 8.0 35 4.5 Mn(65) 0 NO 25 5 NO 10.0 0.3 0.3 40 4.0 Mo(60) 0 NO 28 6 NO 9.5 18.3 10.0 85 0.6 Cd(15) 0 NO 29 7 NO 0.3 16.0 0.7 45 3.2 Pb(75) 0 NO 18 8 NO 0.3 0.3 6.6 40 1.0 Sn(60) 0 NO 28 9 NO 9.0 21.2 9.0 60 0.8 Ni(15), 0 NO 30 Sn(25) 10 NO 0.5 26.2 7.5 92 2.0 Ni(18) 0 NO 45 11 NO 8.0 0.1 6.5 32 0.5 Sn(13), 0 NO 70 Co(55) 12 NO 1.0 15.0 0.8 82 1.5 Ni(9), 0 NO 60 Sn(9) 13 NO 4.0 0.4 6.0 86 0.8 Co(14) 0 NO 50 14 YES 2.0 6.0 2.0 75 2.0 Ni(19), 0 NO 70 Sn(6) 15 YES 3.0 12 3.0 66 0.8 Ni(14), 0 NO 55 Sn(20) 16 YES 0.6 4.0 5.0 88 1.2 Ni(10), 0 NO 70 Sn(2) 17 NO 3.0 0 2.0 — — — 0 NO 0 18 NO 0.2 0.2 8.0 25 0.05 Ni(75) 0 NO 20 19 NO 0.2 28.0 9.0 100 6.0 — 28 YES 100

(117) The resulting Samples 1 to 19 were formed into female terminals of 090 type (a standard of terminals commonly used in automotive industry), and crimped to pure aluminum wire material: as to the respective terminals, measured were: contact resistance between the pure aluminum wire material and the female terminal after leaving in corrosive environment and after leaving in high-temperature and high-humidity environment; and contact resistance between the terminals when a male terminal was fit-connected to the female terminal after leaving in high-heat environment.

(118) —Corrosive Environment Leaving Test—

(119) The female terminal of 090 type crimped to the pure aluminum wire material was soaked in sodium chloride aqueous solution of 5% at 23° C. for 4 hours, then left under high-temperature and high-humidity, 85° C. and 85% RH for 24 hours. After that the contact resistance between the pure aluminum wire material and the terminal was measured by the four-terminal method. The current value was 10 mA.

(120) —High-Temperature and High-Humidity Environment Test—

(121) The female terminal of 090 type crimped to the pure aluminum wire material was left at 85° C. and 85% RH for 96 hours. Then, the contact resistance between the pure aluminum wire material and the terminal was measured by the four-terminal method. The current value was 10 mA.

(122) —High-Heat Environment Leaving Test—

(123) The female terminal of 090 type crimped to the pure aluminum wire was left in 150° C. for 500 hours. After that, the male terminal of 090 type having tin plating was fitted, and the contact resistance (a resistant value) between terminals was measured by the four-terminal method.

(124) TABLE 2 shows these results.

(125) TABLE-US-00002 TABLE 2 LEAVING IN HIGH- LEAVING IN TEMPERATURE LEAVING IN CORROSIVE HGH-HUMIDITY HIGH-HEAT SAMPLE ENVIRONMENT ENVIRONMENT ENVIRONMENT No. (mΩ) (mΩ) (mΩ) 1 6.9 1.5 2.4 2 7.8 3.9 5.0 3 3.9 3.3 4.9 4 3.5 1.9 4.0 5 4.1 1.8 2.9 6 2.6 2.2 3.1 7 2.9 1.5 2.8 8 2.8 2.0 3.0 9 1.9 2.6 3.1 10 1.5 1.9 3.3 11 1.8 1.5 2.3 12 1.0 1.5 3.0 13 1.2 1.8 2.5 14 0.7 1.0 1.1 15 0.6 0.9 1.0 16 0.8 1.2 1.5 17 not less than 2000 3.5 10.2 18 31 5.5 9.8 19 25 12 12

(126) From the results in TABLE 2, it can be found that Samples 1 to 16 have higher corrosion-resistance property in comparison with Samples 17 to 19: in Samples 1 to 16, the zinc layer made of zinc alloy was formed at parts (the planned core contact parts) where the core (aluminum wire material) made of aluminum is in contact with; the zinc layer has thickness not less than 0.1 μm and not more than 5.0 μm and zinc concentration not less than 30% by mass and not more than 95% by mass. Samples 14 to 16 having the undercoat layer of nickel between the base material and the coating film have most excellent corrosion-resistance property among Samples 1 to 16.

(127) Samples 9 to 16, which had the area proportion of the zinc layer to the surface after being formed as the terminal was not less than 30%, had lower resistance value after leaving test in the corrosive environment in comparison with Samples 1 to 8. Among these, Samples 10 to 16 in which the mean crystal grain size of tin or tin alloy in the tin layer at the planned core contact parts was in a range of not less than 0.5 μm and not more than 8.0 μm were controlled so that the crystal grain size of tin to be most optimal size: as a result, the diffusion amount of zinc to the tin layer was controlled to be most optimal, and the resistance value in the leaving test in the corrosive environment was more restricted from rising. Samples 12 to 16 are prevented from rising of the resistance value in the leaving test in the corrosive environment in comparison with Samples 1 to 11: in Samples 12 to 16, the tin layer at the planned core contact parts had the thickness not less than 0.8 μm and not more than 6.0 μm, and the zinc concentration not less than 0.4% by mass and not more than 15% by mass. Samples 14 to 16 in which the undercoat layer made of nickel or nickel alloy was formed between the base material and the zinc layer are prevented from rising of the resistance value after leaving in high-heat environment in comparison with the other Samples.

(128) Compared to this, Sample 17 of the comparative example was not provided with the zinc layer at the planned core contact part, terrific corrosion was found in the leaving test in the corrosive environment and the resistance value was remarkably increased. In Sample 18, the resistance value was increased after the tests of leaving in the high-temperature and high-humidity environment, leaving in the high-heat environment and leaving in the corrosive environment; because the film thickness and the zinc concentration of the zinc layer on the planned core contact parts were not suitable. In Sample 19, the resistance value was increased after the tests of leaving in the high-temperature and high-humidity environment, leaving in the high-heat environment and leaving in the corrosive environment; because the zinc layer was provided at the planned contact parts and the film thickness and the zinc concentration in the zinc layer were not suitable.

INDUSTRIAL APPLICABILITY

(129) It is possible to provide the anti-corrosion terminal material having high anti-corrosion effect using copper or copper alloy base material, the anti-corrosion terminal made of the anti-corrosion terminal material, and the electric wire end structure using the anti-corrosion terminal as a terminal which is crimped to the end of the electric wire made of aluminum wire material.

REFERENCE SIGNS LIST

(130) 1 Anti-corrosion terminal material 2 Base material 3 Undercoat layer 4 Zinc layer 5 Tin layer 6 Surface metal-zinc layer 7 Oxide layer 8 Coating film 81 First coating film 82 Second coating film 10 Anti-corrosion terminal 11 Coupling part 11a Spring tab 12 Electric wire 12a Core (Aluminum wire material) 12b Cover part 13 Core-crimping part 14 Cover-crimping part 25 Planned contact part 26 Planned core contact part