JP6583490B2 - Electrical contact materials for connectors - Google Patents

Description

  The present invention relates to an electrical contact material for a connector.

  As an electrical contact material for a connector, a Cu (copper) alloy is mainly used. A Cu alloy may cause non-conductor or an oxide film having a high electric resistivity to be formed on the surface thereof, thereby causing an increase in contact resistance and a decrease in function as an electric contact material.

  For this reason, a layer of a noble metal such as Au (gold) or Ag (silver) which is not easily oxidized may be formed on the surface of the electrical contact material made of a Cu alloy by plating or the like. However, since the formation of the noble metal layer is expensive, generally, Sn (tin) plating that is inexpensive and has relatively high corrosion resistance is frequently used.

In order to cope with these conventional problems, a technology for forming a CuSn alloy layer on the outermost surface of the electrical contact material for connectors (Patent Document 1), an Sn or Sn alloy layer is formed on the outermost surface, and Cu is formed on the lower side. A technique for forming an alloy layer containing an intermetallic compound mainly containing Sn (Patent Document 2), a technique for forming an Ag ₃ Sn alloy layer on an Sn-based plating layer (Patent Document 3), and the like have been proposed. .

  However, it cannot be said that the above-described conventional technique can sufficiently solve the above-described problem. Therefore, the present inventor has intensively studied and developed a method for forming a layer made of a conductive oxide or hydroxide on the outermost surface of the connector electrical contact material (Patent Documents 4 and 5). Patent Document 4 discloses a method of heating a multilayer metal layer in an oxidizing atmosphere after forming a multilayer metal layer by laminating a plurality of metal layers on a base material. According to this method, a conductive oxide layer containing an oxide such as Sn, Ni and Cu can be formed on the surface of the alloy layer. Once this conductive oxide layer is formed, oxidation does not proceed any more, so that the conductivity can be maintained over a long period of time, and a stable low contact resistance can be obtained. And since the alloy layer formed on the base material is hard and excellent in wear resistance and has a low friction coefficient, the insertion force at the time of terminal insertion can be made sufficiently small.

  In Patent Document 5, after forming an alloy layer such as NiSn or CuSn on a substrate, the insulating oxide layer formed on the surface is once removed, and oxidation treatment or hydroxylation treatment is performed again. A method of applying is disclosed. According to this method, a conductive oxide layer containing an oxide such as Sn, Ni and Cu or a conductive hydroxide layer containing a hydroxide such as Sn, Ni and Cu is formed on the surface of the alloy layer. can do. Also by this method, the same effect as described above can be obtained.

JP 2010-267418 A JP 2011-12350 A JP 2011-26677 A JP 2012-222659 A JP 2012-237055 A

  However, when the technique of Patent Document 4 is applied, there is a problem that the metal of the base material diffuses toward the surface side by heating in the step of forming the conductive oxide layer. When the metal of the base material reaches the alloy layer or the conductive oxide layer, the composition of these layers changes from the intended composition. As a result, there is a possibility of causing a decrease in conductivity.

  In order to solve the above problem, a technique for suppressing diffusion of metal from a base material by providing a diffusion barrier layer such as a Ni (nickel) layer on the base material is known. However, in the conventional diffusion barrier layer, depending on the heating temperature, the heating time, the thickness of the diffusion barrier layer, etc., the metal of the base material may diffuse to the alloy layer etc. when the multilayer metal layer is heated, resulting in a decrease in conductivity. May be incurred.

  On the other hand, in order to suppress metal diffusion of the base material, methods such as lowering the heating temperature, shortening the heating time, and increasing the thickness of the diffusion barrier layer are conceivable. However, when the heating temperature is excessively lowered or the heating time is excessively shortened, the formation of the conductive oxide layer may be insufficient. Moreover, when the thickness of the diffusion barrier layer is excessively increased, there is a possibility that productivity is lowered and cost is increased.

  As described above, when the technique of Patent Document 4 is applied, the range of optimum conditions that can achieve both the suppression of metal diffusion from the base material and the formation of the conductive oxide layer is relatively narrow. There's a problem. Therefore, in order to more easily manufacture an electrical contact material having excellent conductivity, a technique that can widen the range of the optimum conditions is required.

  Further, when the technique of Patent Document 5 is applied, there is a problem that the process becomes complicated because it is necessary to provide a process for once removing the insulating oxide layer. Therefore, an electrical contact material for a connector that can easily form a conductive oxide or hydroxide layer on the surface without providing a step of once removing the insulating oxide layer formed during alloying. Development of a manufacturing method is desired.

  The present invention has been made in view of such a background, and is intended to provide an electrical contact material for a connector that is easy to manufacture and can maintain a low contact resistance over a long period of time.

One aspect of the present invention is a base material made of metal,
A diffusion barrier layer comprising an intermetallic compound of Cu ₆ Sn ₅ , Ni ₃ Sn ₄ , Ni ₃ Sn _2, or NiSn ₃ and formed on the base material;
Oxides of Sn which have a conductivity, a hydroxide or contains a hydroxide oxide, formed on the outermost surface conductive film layer,
A residual Sn layer made of Sn and disposed between the diffusion barrier layer and the conductive coating layer ;
The conductive coating layer is
It has an electrical characteristic that the contact resistance is less than 10 mΩ when a hemispherical convex portion with a radius of 3 mm provided on the hard Au plating material is brought into contact with a contact load of 1 N,
It exists in the electrical contact material for connectors whose thickness is 5-500 nm.

  The connector electrical contact material (hereinafter referred to as “electrical contact material” as appropriate) has a conductive coating layer having electrical conductivity on the outermost surface. Thereby, compared with the conventional Sn plating film, the said electrical contact material improves durability in a high temperature environment, and can maintain low contact resistance over a long period of time. This is clear from the examples described later.

FIG. 3 is a partial cross-sectional view showing a configuration of an electrical contact material for a connector in Example 1. In Example 1, (a) a partial cross-sectional view of the intermediate material before forming the diffusion barrier layer, (b) a partial cross-sectional view of the intermediate material after forming the diffusion barrier layer, (c) on the diffusion barrier layer The partial cross section figure of the intermediate material in the state where the multilayer metal layer is formed in. The contact load-contact resistance curve which shows the result of the initial evaluation performed using the electrical contact material (sample E1) in Example 1. The contact load-contact resistance curve which shows the result of the evaluation after a high temperature endurance test performed using the electric contact material (sample E1) in Example 1. The contact load-contact resistance curve which shows the result of the high-humidity endurance test performed using the electrical contact material (sample E1) in Example 1. The contact load-contact resistance curve which shows the result of the initial stage evaluation performed using the electrical contact material (sample E2) in Example 2. The contact load-contact resistance curve which shows the result of the high-temperature endurance test performed using the electrical contact material (sample E2) in Example 2. The contact load-contact resistance curve which shows the result of the high-humidity endurance test performed using the electrical contact material (sample E2) in Example 2. The contact load-contact resistance curve which shows the result of the initial evaluation performed in Example 3 using the electrical contact material (sample E3). The contact load-contact resistance curve which shows the result of the high-temperature endurance test performed using the electrical contact material (sample E3) in Example 3. The contact load-contact resistance curve which shows the result of the high-humidity endurance test performed using the electrical contact material (sample E3) in Example 3.

  The base material used for the electrical contact material can be selected from various metals having conductivity. Specifically, as the base material, Cu, Al (aluminum), Fe (iron), or an alloy containing these metals is preferably used. These metal materials are excellent not only in electrical conductivity but also in formability and springiness, and can be applied to various types of electrical contacts. As the shape of the base material, there are various shapes such as a rod shape and a plate shape, and the dimensions such as the thickness can be variously selected according to the application. In general, the thickness is preferably about 0.2 to 2 mm.

The diffusion barrier layer contains an intermetallic compound of Cu ₆ Sn ₅ , Ni ₃ Sn ₄ , Ni ₃ Sn _2, or NiSn ₃ . These intermetallic compounds have a high effect of suppressing diffusion of metal from the base material, for example, when a reflow process is performed in the manufacturing process of the electrical contact material. These intermetallic compounds can be easily formed by, for example, a method in which Cu or Ni is reacted with Sn to form an alloy on a base material.

  The electrical contact material essentially contains Sn on the diffusion barrier layer, and further includes one or more additive elements M selected from the group consisting of Cu, Zn, Co, Ni and Pd. You may have. The content ratio of the additive element M contained in the intermediate layer can be appropriately set according to the type of the additive element M so that the intermediate layer has conductivity. From the viewpoint of conductivity, the additive element M preferably contains Cu having high conductivity.

The intermediate layer preferably contains an intermetallic compound such as Cu ₆ Sn ₅ , Ni ₃ Sn ₄ , Ni ₃ Sn ₂ or NiSn ₃ . Due to the presence of these intermetallic compounds in the intermediate layer, low contact resistance can be maintained for a long time in a high humidity environment.

When Cu ₆ Sn ₅ is contained in the intermediate layer, a part of Cu in Cu ₆ Sn ₅ is replaced with one or more substitution elements M ′ selected from Zn, Co, Ni and Pd. More preferably. That is, it is more preferable that (Cu, M ′) ₆ Sn ₅ is included in the intermediate layer. In this case, a low contact resistance can be maintained for a longer period in a high humidity environment. The reason is considered as follows.

When Cu ₆ Sn ₅ is left in a high-humidity environment, it changes to another form of intermetallic compound called Cu ₃ Sn having a higher resistivity, thereby increasing the contact resistance. On the other hand, (Cu, M ′) ₆ Sn ₅ is less likely to change to Cu ₃ Sn than Cu ₆ Sn ₅ and can maintain the state of (Cu, M ′) ₆ Sn ₅ for a longer period. It is considered possible. Thereby, it is considered that a low contact resistance can be maintained for a long period of time in a high humidity environment.

In order to reliably generate (Cu, M ′) ₆ Sn ₅ in the intermediate layer, the total of Cu and the substitution element M ′ among Sn, Cu and substitution element M ′ present in the intermediate layer is 1 to 50 atoms. It is preferable to control the total amount of Cu and the substitution element M ′ in the electrical contact material so that it becomes%. Moreover, from the viewpoint of further improving the durability in a high humidity environment, it is more preferable that the total of Cu and the substitution element M ′ in the intermediate layer is in the range of 5 to 10 atomic%.

Wherein the conductive coating layer, an oxide of Sn having conductivity, hydroxide or hydroxide oxide (hereinafter, these compounds of the conductive Sn compound.) Are included. The conductive Sn compound is represented by a composition formula such as SnO _a (a ≠ 1) or Sn ₃ O ₂ (OH) ₂ . The conductive coating layer may further contain other compounds such as an oxide of the additive element M, a hydroxide of the additive element M, and inevitable impurities. The thickness of the conductive coating layer is preferably 5 to 500 nm, and more preferably 10 to 200 nm.

The conductive coating layer preferably contains one or more additive elements M in the form of an oxide or hydroxide. Examples of the oxide or hydroxide of the additive element M include CuO _b (b ≠ 1), ZnO _c (c ≠ 1), CoO _d (d ≠ 1), NiO _e (e ≠ 1), and PdO _f (f ≠ 1) etc. When these compounds coexist with the conductive Sn compound, the electrical contact material can maintain a low contact resistance in a high temperature environment for a long period of time. The reason is considered as follows.

  The conductive Sn compound changes to more stable SnO in a high temperature environment. And contact resistance increases by changing a conductive Sn compound into SnO which is a nonconductor. On the other hand, when the oxide and / or hydroxide of the additive element M and the conductive Sn compound coexist in the conductive film layer, it is considered that the above-described change to SnO is suppressed. Thereby, it is considered that the electrical contact material can maintain a low contact resistance for a long period of time in a high temperature environment.

  The conductive coating layer preferably contains two or more additive elements M in the form of oxides or hydroxides. In this case, since the effect of suppressing deterioration of the conductive Sn compound is further increased, a low contact resistance can be maintained for a longer period in a high temperature environment.

  In order to ensure that the conductive Sn compound and the oxide of the additive element M coexist in the conductive coating layer, the additive element M content of the additive element M and Sn present in the intermediate layer is 1 to 50 atoms. It is preferable to control the total amount of the additive element M in the electrical contact material so as to be%.

The electrical contact material can be produced, for example, by the following method. First, an intermediate material having a diffusion barrier layer containing an intermetallic compound of Cu ₆ Sn ₅ , Ni ₃ Sn ₄ , Ni ₃ Sn ₂ or NiSn ₃ on a base material made of metal is prepared. The intermediate material having such a configuration can be produced by a conventionally known method.

For example, the intermediate material is an intermediate in which at least one of a Cu layer or a Ni layer and an Sn layer are formed on the base material, and then these metal layers are heated to form the intermetallic compound. It can produce by performing material reflow processing. That is, an intermediate material having a diffusion barrier layer containing Cu ₆ Sn ₅ is formed by forming a Cu layer and an Sn layer on a base material, and then heating these metal layers to alloy Cu and Sn. can do. Similarly, an intermediate material having a diffusion barrier layer containing Ni ₃ Sn ₄ , Ni ₃ Sn ₂ or NiSn ₃ is formed by forming a Ni layer and a Sn layer on a base material, and then heating these metal layers to form Ni and Sn. It can be produced by alloying with Sn. Alternatively, the intermediate material reflow process may be performed in a state where the Ni layer, the Cu layer, and the Sn layer are stacked on the base material, and a diffusion barrier layer may be formed at the interface between the Sn layer and the Ni layer and / or the Cu layer. Good.

  The heating temperature in the intermediate material reflow treatment can be appropriately selected from a range of 280 to 450 ° C., for example. Moreover, when heating in the said specific temperature range, it is preferable to set a heating time in the range of 5 to 40 seconds.

  The diffusion barrier layer formed by the intermediate material reflow process can densely cover the surface of the base material. Therefore, in this case, the diffusion of the metal from the base material can be more effectively suppressed. Moreover, the intermediate material which has the said diffusion barrier layer is marketed, for example with forms, such as a reflow Sn plating strip material, and is easy to acquire.

  Note that the diffusion barrier layer may be exposed on the surface of the intermediate material, and another metal layer such as an Sn layer may exist on the diffusion barrier layer.

  Next, on the diffusion barrier layer, an Sn layer and an M layer (provided that the M layer is a single layer composed of one or more additive elements M selected from Cu, Zn, Co, Ni, and Pd) A multilayer metal layer is formed by laminating two or more metal layers including two or more metal layers) so that a metal layer made of the metal that is hardly oxidized among the plurality of metal layers is an outermost layer. The Sn layer and the M layer may exist in the intermediate material in advance, or may be formed by performing a plating process or the like as necessary.

  Thereafter, the multi-layer metal layer is heated in an oxidizing atmosphere to perform a reflow process, thereby forming a conductive coating layer on the outermost surface. At this time, an intermediate layer containing Sn and the additive element M can be formed between the diffusion barrier layer and the conductive coating layer according to the configuration of the multilayer metal layer. As described above, by arranging a metal layer made of the metal that is hardly oxidized in the outermost layer of the multilayer metal layer, it is possible to suppress excessive generation of an insulating oxide during the reflow process, and to improve the contact resistance of the electrical contact material. Can be made lower.

  According to the manufacturing method of the above aspect, the intermediate layer and the conductive film layer can be simultaneously formed by performing the reflow treatment on the multilayer metal layer, and the conventional insulating oxide film is removed. It is not necessary to carry out the process to do.

  Furthermore, according to the manufacturing method of the said aspect, the said electrical-contact material can be produced using the said intermediate material in which the said diffusion barrier layer was formed previously. The specific intermetallic compound contained in the diffusion barrier layer has a higher effect of suppressing metal diffusion from the base material than a conventional diffusion barrier layer. Therefore, it is possible to effectively suppress the metal of the base material from diffusing toward the intermediate layer and the conductive coating layer during the reflow process. As a result, the heating conditions in the reflow process can be selected from a wider range than in the conventional case.

  As described above, according to the manufacturing method of the above aspect, the conductive film layer can be formed by a simple process called the reflow process, and the heating conditions in the reflow process are selected from a wider range. be able to. Therefore, the manufacturing method of the above aspect can more easily produce the electrical contact material having excellent conductivity.

  The heating temperature in the said reflow process can be suitably selected from the range of 250-350 degreeC, for example. Moreover, when the heating temperature in a reflow process is the said specific temperature range, it is preferable to set a heating time in the range of 30 to 180 seconds.

Example 1
Examples of the electrical contact material for connectors will be described with reference to the drawings. As shown in FIG. 1, the electrical contact material 1 of this example includes a base material 2 made of a Cu alloy, a diffusion barrier layer 3 formed on the base material 2, and an intermediate layer formed on the diffusion barrier layer 3. 4 and a conductive coating layer 5 formed on the outermost surface. The diffusion barrier layer 3 contains Cu ₆ Sn ₅ . The intermediate layer 4 essentially contains Sn, and further contains Cu and Zn as additive elements M. The conductive coating layer 5 contains Sn oxide, hydroxide or hydroxide having conductivity. Hereinafter, the detailed structure of the electrical contact material 1 is demonstrated with a manufacturing method.

[Preparation of intermediate material 10]
An intermediate material 10 having a diffusion barrier layer 3 containing Cu ₆ Sn ₅ on a base material 2 made of a Cu alloy was prepared. In this example, an intermediate material 10 produced by the following procedure was prepared. First, the Cu plating process and the Sn plating process were sequentially performed on the base material 2, and the Cu layer 100 and the Sn layer 101 were formed on the base material 2 as shown in FIG. The film thicknesses of the Cu layer 100 and the Sn layer 101 were 0.2 μm and 1.5 μm, respectively.

  Next, the Cu layer 100 and the Sn layer 101 were heated at 400 ° C. for 10 seconds to perform an intermediate material reflow treatment, and Cu was alloyed with Sn to form the diffusion barrier layer 3. The intermediate material 10 shown in FIG.2 (b) was obtained by the above. In the obtained intermediate material 10, the surface of the base material 2 was covered with the diffusion barrier layer 3. In this example, since the amount of Sn was excessive with respect to Cu, a part of the Sn layer 101 remained on the diffusion barrier layer 3. The film thicknesses of the diffusion barrier layer 3 and the Sn layer 101 were 0.5 μm and 1.1 μm, respectively.

When the composition of the diffusion barrier layer 3 was analyzed by SEM-EDX (scanning electron microscope-energy dispersive X-ray spectroscopy), it was confirmed that the diffusion barrier layer 3 was composed of Cu ₆ Sn ₅ . In addition, as shown in FIG. 2B, the growth mode of Cu ₆ Sn ₅ was island growth.

[Formation of multilayer metal layer 11]
Next, Zn plating treatment and Cu plating treatment were sequentially performed on the surface of the intermediate material 10 to form the multilayer metal layer 11. As shown in FIG. 2C, the multilayer metal layer 11 has a three-layer structure in which an Sn layer 101, a Zn layer 111, and a Cu layer 112 are sequentially stacked on the diffusion barrier layer 3. In addition, among these three layers, the Cu layer 112 that is hardly oxidized is disposed in the outermost layer. Note that the Sn layer 101 is a layer that was previously present in the intermediate material 10 before the plating process. The conditions for the Zn plating process and the Cu plating process are as follows.

(Zn plating treatment)
・ Liquid composition of plating bath Zinc chloride (ZnCl ₂ ): 60 g / L
Sodium chloride (NaCl): 35 g / L
Sodium hydroxide (NaOH): 80 g / L
・ Film thickness: 0.25μm
・ Liquid temperature: 25 ° C
・ Current density: 1 A / dm ²

(Cu plating treatment)
・ Liquid composition of plating bath Copper sulfate (CuSO ₄ ): 180 g / L
Sulfuric acid (H ₂ SO ₄ ): 80 g / L
Chlorine ion (Cl ⁻ ): 40 mL / L
・ Film thickness: 0.15μm
・ Liquid temperature: 20 ℃
・ Current density: 1 A / dm ²

[Reflow processing]
Next, the multilayer metal layer 11 was heated in an oxidizing atmosphere to perform a reflow process. Specifically, the intermediate material 10 with the multilayer metal layer 11 formed thereon was placed in an air atmosphere and heated at 270 ° C. for 120 seconds for reflow treatment. Thus, an electrical contact material 1 was obtained.

  The obtained electrical contact material 1 was cut in the thickness direction, and cross-sectional observation was performed using SEM-EDX. As a result, the electrical contact material 1 of this example has a structure in which a diffusion barrier layer 3, an intermediate layer 4, a remaining Sn layer 6 and a conductive coating layer 5 are sequentially laminated on a base material 2, as shown in FIG. I confirmed that I have it. The remaining Sn layer 6 existing between the intermediate layer 4 and the conductive coating layer 5 is a portion of the Sn layer 101 pre-existing in the intermediate material 10, and Sn that has not been spent on alloying with Cu and Zn remains. It is a layer formed.

As a result of the EDX analysis, it was confirmed that the intermediate layer 4 contained Sn, Cu, and Zn. Further, from these composition ratios, it was confirmed that the intermediate layer 4 was composed of (Cu, Zn) ₆ Sn ₅ in which Sn, Cu and Zn were alloyed. As shown in FIG. 1, the growth mode of (Cu, Zn) ₆ Sn ₅ was island growth.

  Next, composition analysis of the conductive coating layer 5 was performed using XPS (X-ray photoelectron spectroscopy). As a result, it was confirmed that the conductive coating layer 5 contains Sn, Cu, and Zn. Moreover, it was confirmed that these metals existed in any form of oxide, hydroxide or hydroxide oxide. In XPS, it is possible to distinguish between a state in which a metal exists as a simple substance and a state in which a metal exists as a compound such as an oxide. In reality, it is difficult to determine whether or not it exists.

  As described above, from the results of the SEM-EDX analysis and the XPS analysis, the Sn layer 101, the Zn layer 111, and the Cu layer 112 in the multilayer metal layer 11 are subjected to the reflow process, so that the intermediate layer 4 and the conductive coating layer shown in FIG. 5 and the remaining Sn layer 6 were confirmed. The film thicknesses of the intermediate layer 4 and the conductive coating layer 5 in this example were 1.2 μm and 0.04 μm, respectively.

  Next, using the sample (sample E1) collected from the electrical contact material 1 of this example, measurement of contact resistance in the initial state (initial evaluation), measurement of contact resistance after performing a high temperature durability test (after the high temperature durability test) Evaluation) and three types of measurement of contact resistance after high humidity endurance test (evaluation after high humidity endurance test) were performed. The high temperature durability test is a test in which a sample is left in an environment at a temperature of 160 ° C. for 120 hours. The high humidity durability test is a test in which a sample is left for 96 hours in an environment of a temperature of 85 ° C. and a relative humidity of 85% RH.

  The contact resistance was measured according to the following procedure. First, a hard Au plating material having a hemispherical convex part with a radius of 3 mm was prepared as a contact, and the hemispherical convex part was brought into contact with the sample to be measured. In this state, measurement of the contact resistance between the sample E1 and the contact was started, and the contact load applied between them was gradually increased. When the contact load reached 40 N, the increase in the contact load was stopped, and then the contact load applied between the two was gradually reduced. The contact resistance measurement was completed when they were separated. 3 to 5 show changes in contact resistance in the initial evaluation, the evaluation after the high temperature durability test, and the evaluation after the high humidity durability test, respectively. 3 to 5, the vertical axis represents the value of contact resistance, and the horizontal axis represents the value of the contact load applied between the sample E1 and the contact. In addition, five measurements were performed for each of the initial evaluation, the evaluation after the high temperature durability test, and the evaluation after the high humidity durability test.

  As is known from FIGS. 3 to 5, the sample E1 has a contact resistance of 10 mΩ when a contact load of 1 N is applied in any of the initial evaluation, the evaluation after the high temperature durability test, and the evaluation after the high humidity durability test. Was less than. These results sufficiently satisfy the performance required for the connector terminals. From these results, it can be understood that the sample E1 can maintain a low contact resistance over a long period even in a high temperature environment and a high humidity environment.

  In this example, since Sn was excessive with respect to Cu and Zn, the remaining Sn layer 6 was formed between the intermediate layer 4 and the conductive coating layer 5. It is also possible to produce the electrical contact material 1 that does not have the remaining Sn layer 6 by changing the film thickness. The electrical contact material 1 that does not have the remaining Sn layer 6 can maintain a low contact resistance over a long period of time in a high-temperature environment and a high-humidity environment, similarly to the electrical contact material 1 that has the remaining Sn layer 6. .

(Example 2)
This example is an example of the electrical contact material 1 manufactured by changing the heating conditions of the reflow process in Example 1. The electrical contact material 1 of this example was produced in the same manner as in Example 1 except that the heating time in the reflow process was changed to 90 seconds.

  Using the sample (sample E2) collected from the electrical contact material 1 of this example, the contact resistance was measured in the same manner as in Example 1. The results are shown in FIGS. 6 to 8, the vertical axis represents the value of contact resistance, and the horizontal axis represents the value of the contact load applied between the sample E2 and the contact. In addition, five measurements were performed for each of the initial evaluation, the evaluation after the high temperature durability test, and the evaluation after the high humidity durability test.

  As is known from FIGS. 6 to 8, the sample E2 has a contact resistance of 10 mΩ when a contact load of 1 N is applied in any of the initial evaluation, the evaluation after the high temperature durability test, and the evaluation after the high humidity durability test. Was less than. These results sufficiently satisfy the performance required for the connector terminals. Moreover, it can be understood from these results that the sample E2 can maintain a low contact resistance over a long period of time even in a high temperature environment and a high humidity environment.

Example 3
This example is an example of the electrical contact material 1 manufactured by changing the heating conditions of the reflow process in Example 1. The electrical contact material 1 of this example was produced in the same manner as in Example 1 except that the heating time in the reflow process was changed to 180 seconds.

  Using the sample (sample E3) collected from the electrical contact material 1 of this example, the contact resistance was measured in the same manner as in Example 1. The results are shown in FIGS. In addition, the vertical axis | shaft of FIGS. 9-11 is the value of contact resistance, and a horizontal axis is the value of the contact load provided between the sample E3 and the contactor. In addition, five measurements were performed for each of the initial evaluation, the evaluation after the high temperature durability test, and the evaluation after the high humidity durability test.

  As is known from FIGS. 9 to 11, the sample E3 has a contact resistance of 10 mΩ when a contact load of 1 N is applied in any of the initial evaluation, the evaluation after the high temperature durability test, and the evaluation after the high humidity durability test. Was less than. These results sufficiently satisfy the performance required for the connector terminals. Moreover, it can be understood from these results that the sample E3 can maintain a low contact resistance over a long period of time even in a high temperature environment and a high humidity environment.

Moreover, according to the result of the contact resistance measurement of the samples E1 to E3, the shape of the contact load-contact resistance curve (FIGS. 3 to 11) of the electrical contact material 1 is almost the same even when the heating condition in the reflow process is changed. It was the same. Therefore, by adopting the manufacturing method of the above aspect, the heating conditions in the reflow process can be selected from a wider range than in the past, and the electrical contact material 1 having excellent conductivity can be more easily manufactured. Can understand.
The reference form of the electrical contact material for a connector according to the present invention is shown below.
[Claim 1]
A base material made of metal,
A diffusion barrier layer comprising an intermetallic compound of Cu ₆ Sn ₅ , Ni ₃ Sn ₄ , Ni ₃ Sn _2, or NiSn ₃ and formed on the base material;
Having conductivity, and having a conductive film layer formed on the outermost surface,
The conductive coating layer is
It has an electrical characteristic that the contact resistance is less than 10 mΩ when a hemispherical convex portion with a radius of 3 mm provided on the hard Au plating material is brought into contact with a contact load of 1 N,
An electrical contact material for a connector having a thickness of 5 to 500 nm.
[Section 2]
Item 2. The electrical contact material for connectors according to Item 1, wherein the conductive coating layer has a thickness of 10 to 200 nm.

1 Electrical contact material 2 Base material 3 Diffusion barrier layer 4 Intermediate layer 5 Conductive coating layer

Claims (2)

A base material made of metal,
A diffusion barrier layer comprising an intermetallic compound of Cu ₆ Sn ₅ , Ni ₃ Sn ₄ , Ni ₃ Sn _2, or NiSn ₃ and formed on the base material;
Oxides of Sn which have a conductivity, a hydroxide or contains a hydroxide oxide, formed on the outermost surface conductive film layer,
A residual Sn layer made of Sn and disposed between the diffusion barrier layer and the conductive coating layer ;
The conductive coating layer is
It has an electrical characteristic that the contact resistance is less than 10 mΩ when a hemispherical convex portion with a radius of 3 mm provided on the hard Au plating material is brought into contact with a contact load of 1 N,
An electrical contact material for a connector having a thickness of 5 to 500 nm.   The electrical contact material for a connector according to claim 1, wherein the conductive coating layer has a thickness of 10 to 200 nm.

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