JP2000169996A - Metallic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve both the prevention of time deterioration in a high temp. environment such as the place around an automotive engine and inserting and withdrawing resistance of a metallic material. SOLUTION: The surface of a base material of copper or a copper alloy is electroplated with, as an intermediate layer, a nickel alloy plating intermediate layer contg. phosphourus or boron by 0.05 to 20% in total, the surface layer is plated with tin or a tin alloy, thereafter, reflowing treatment is made, and the concns. of phosphorus and boron in the plated layer are limited to 0.01 to 1%, by which its heat resistance and inserting and withdrawing resistance are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an intermediate layer which contains at least phosphorus and / or boron and Ni and has a tin or tin alloy layer as a surface layer. The present invention relates to a metal material for an electronic component having excellent insertability.

[0002]

2. Description of the Related Art Tin- or tin-alloy-plated metal contacts for electronic parts are mainly used in large quantities as consumer connector contacts and automotive wiring harnesses. However, tin or tin alloy plating materials undergo interdiffusion between the underlying metal, such as copper or nickel, and the surface plating layer, and have various properties such as contact resistance, heat-peeling resistance, and solderability over time. Deteriorates. That is, the characteristics deteriorate due to aging. Since this phenomenon is accelerated as the temperature becomes higher, the deterioration is particularly severe around an engine of an automobile.

Under these circumstances, the USCAR, which is established by three major automobile manufacturers in the United States and determines the standards of automobile parts, is increasing the demand for heat resistance of the connector material, and the most severe use conditions , Heat resistance is required at a normal use temperature of 155 ° C. and a maximum use temperature of 175 ° C. Also in Japan, the demand for heat resistance has been increasing, especially for automotive-related connector materials, and heat resistance at about 150 ° C. has been demanded.

[0004] Further, there is a case where after the material is plated, it is left for a long time and then used after the connector maker's production base is relocated overseas. For this reason, there is a demand for a material that does not deteriorate various properties of the plated material even when stored for a long period of time, that is, a material having high aging resistance. In addition,
Deterioration of the properties of the plated material is promoted at high temperatures. Therefore, a material that has little property deterioration at high temperatures can be rephrased as a material that does not deteriorate in properties even when stored for a long period of time. Therefore, a plating material having high heat resistance is also required in this field.

[0005] The above-mentioned deterioration in characteristics can be alleviated to some extent by plating with copper or nickel as an intermediate layer. But,
When copper is used as the intermediate layer, the heat-resistant peeling property is significantly deteriorated.
When nickel is used as the intermediate layer, the characteristics are improved as compared with the case where copper is used as the base because nickel suppresses the diffusion of copper, but it is not sufficiently satisfactory from the viewpoint of solderability. In addition, post-treatments such as sealing treatment after plating have been attempted, but have not been improved.

As a means for suppressing the diffusion of copper, a means in which a copper-nickel alloy is present in the middle has been proposed (PCT / US96 / 19768). Although mentioned, there is no solution to the prevention of aging deterioration of solderability.

[0007] Further, as a problem inherent in the tin-plated material,
The tin-plated material has a gas tight structure in which a male and a female adhere to each other at the contact point of the connector due to its softness. For this reason, there is a disadvantage that the insertion force of the connector is higher than that of a connector formed by gold plating or the like.

Under these circumstances, demands for multi-core connectors have been increasing in recent years with the progress of miniaturization, weight reduction, and multi-functionality not only for automobile parts but also for general connectors. . However, when multicore is performed with the current tin-plated material, the insertion force of the connector increases. In an automobile assembling process in which tin-plated connectors are frequently used, since connectors are joined by input, an increase in insertion force directly leads to a decrease in workability.

To cope with this, there has been proposed a method in which copper or nickel is plated as an intermediate layer to reduce the frictional resistance of the tin plating or tin alloy plating on the surface layer and to improve the insertion / extraction property (Japanese Patent Laid-Open Publication No. HEI 9-26139). 9-320668),
According to this method, the problem relating to the insertion of the connector can be avoided, but as described above, it is not possible to prevent the heat resistance, particularly the deterioration of the solderability over time.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to prevent deterioration over time in a high temperature environment around an engine of an automobile, to improve both insertion and removal resistance, and to improve solderability even when stored for a long period of time. The present invention provides tin or tin alloy plating, which also has the performance of not deteriorating the characteristics.

[0011]

Accordingly, as a result of conducting research to solve the above-mentioned problems, (1) phosphorus and / or boron are added in a total amount of 0.05% to 20% with respect to a copper or copper alloy base material.
The nickel alloy plating intermediate layer contained is electroplated, and further subjected to a reflow treatment after forming a tin or tin alloy layer plating surface layer, so that the concentration of phosphorus and / or boron in the tin or tin alloy plating layer is 0.01% to 1%. %, A metal material having high heat resistance and aging resistance. (2) Phosphorus and / or boron are added in a total of 0.0
The nickel alloy plating intermediate layer containing 5% to 20% is electroplated, and further subjected to a reflow treatment after a tin or tin alloy layer plating surface layer, so that the concentration of phosphorus and boron in the tin or tin alloy plating layer is 0.1%. A metal material for a terminal / connector contact having improved insertion / extraction properties, characterized in that the content is 0.01% to 1%.

(3) The intermediate layer is a nickel alloy containing 0.05 to 20% in total of phosphorus and / or boron and 10 to 60% of one or more of Sn, Cu and Zn. The metal material according to (1) or (2), wherein (4) The metal material according to (1) to (3), wherein the thickness of the surface layer is 0.3 μm to 3 μm.
(5) The metal material according to (1) to (3), wherein the thickness of the intermediate layer is 0.5 μm to 3 μm.

(6) A nickel alloy plating intermediate layer containing 0.05% to 20% in total of phosphorus and / or boron is electroplated on a copper or copper alloy base material. After the surface plating, a reflow treatment (and / or a heat treatment) is performed, and then phosphorus and / or boron contained in the intermediate layer is diffused to the surface of the tin or tin alloy plating layer. Improved metal material for terminals and connectors. (7) The metal material for electronic parts according to (6), wherein the thickness of the diffusion layer of tin and nickel is 1.0 μm or less, and the planar diameter of the diffusion layer is 1.0 μm or less. (8) The metal material for electronic parts according to (1) to (4), wherein the carbon concentration in the tin or tin alloy plating layer is 0.05 to 0.5%. (9) The method according to (1) or (6), wherein after the reflow treatment or the heat treatment, the substrate is immersed in an aqueous solution containing 0.1 to 2 mol / L of phosphate ions or electrolytically treated using the material as an anode in the aqueous solution. Of producing a metal material for electronic parts.

(10) The metal material for electronic parts according to (1) or (6), wherein a film of an organic phosphorus compound or an inorganic phosphorus compound is formed after the reflow treatment or the heat treatment. (11) The method for producing a metal material according to (1) or (5), wherein a sealing treatment or a lubricant treatment is performed after the reflow treatment or the heat treatment.
(12) A terminal and a connector characterized by using the metal material described in the above (1) to (7) as a contact have been found.

In the intermediate layer, nickel is a base element for putting phosphorus, boron, copper, tin, and zinc into the intermediate layer, and alloy plating can be performed with any of these elements. In addition, nickel has an effect of suppressing the diffusion of copper, which is a cause of deterioration of heat resistance. But,
When only nickel is used as a base, deterioration of solderability after high-temperature heating cannot be prevented. It is presumed that when only nickel is the intermediate layer, heating (155 ° C., 16 hours) promotes oxidation of the inside of the plating layer and partially generates nickel oxide, thereby deteriorating solderability. are doing.

On the other hand, when a nickel alloy containing phosphorus and / or boron is used as the intermediate layer, phosphorus and boron diffuse into the surface and the inside of the tin or tin alloy plating layer on the surface by reflow treatment or subsequent aging treatment. However, it is presumed that these elements prevent oxidation of the inside and the surface layer and suppress deterioration of solderability.

Furthermore, it is presumed that these oxide films are formed by the diffusion of phosphorus and / or boron to the surface, and this film lowers the insertion / extraction resistance when used for a connector. In addition, an alloy obtained by adding phosphorus and boron to nickel has a characteristic that it is extremely hard as compared with plating of a base material and a surface layer. For example, if phosphorus is 1 to 15 in nickel
When alloy plating containing% is performed, the Vickers hardness (Hv) reaches 250 to 700. Furthermore, when a tin or tin alloy plating is performed thereon and reflow treatment is performed, the temperature rises to 300 to 800. On the other hand, the hardness of tin or tin alloy plating on the surface layer is around 10. Since the hardness of the surface layer and the hardness of the intermediate layer are remarkably different from each other, it is also presumed that a thin-film metal lubrication effect also occurs, and the insertion / removal resistance is reduced.

The total content of phosphorus and / or boron in the intermediate layer may be determined according to the required heat resistance.
If it is less than 05%, no effect can be obtained, more preferably 0.5%.
% Is desirable. In addition, the upper limit of 20
% Is the upper limit value at which alloy plating of these metals with nickel is possible, and it is difficult to further contain phosphorus and boron. Further, when the total value of the phosphorus and boron contents exceeds 15%, the tensile stress in the plating film increases, and cracking of the plating easily occurs. Therefore, the content is more preferably 15% or less.

As elements to be added in addition to phosphorus and boron, copper and zinc are used to supplement the low workability of nickel-phosphorus and nickel-boron alloys, and tin is used to further improve the hardness of the intermediate layer. It is added as necessary to improve the insertion / extraction properties. It contains 10 to 60% of at least one of tin, copper and zinc. If the total value of these elements is less than 10%, the effect of each element will not be sufficiently exhibited. On the other hand, if it exceeds 60%, diffusion of copper, which is an original effect of nickel, cannot be suppressed. Since cobalt is contained as an unavoidable impurity in a nickel plating bath or anode, depending on the nickel salts used in the bath and the quality of the anode, 1-2% is contained in the plating film.
Although there is a possibility of contamination, the amount of such an amount does not significantly affect the characteristics of the nickel-phosphorus alloy and the nickel-phosphorus-boron alloy plating, so that cobalt as an impurity can be ignored.

If the thickness of the intermediate layer is less than 0.5 μm, the above-mentioned effect of heat resistance cannot be obtained.
More preferably, it is required to be 1.0 μm or more. If the thickness is too large, the pressability is impaired.
m or less.

The thickness of the diffusion layer is preferably 1 μm or less. If it exceeds 1 μm, the surface pure Sn or Sn alloy plating layer becomes relatively thin and the heat resistance deteriorates. or,
The particle size is observed by dissolving only the pure plating portion of the surface layer of the plating by an electrolytic method and peeling off the plating layer. When the average particle diameter of the diffusion layer exceeds 1 μm, when the solder is wet on the surface of the diffusion layer, the surface area to be wetted is small, and the solderability is reduced. Therefore, the average particle diameter needs to be 1 μm or less, and more preferably 0.8 μm or less. It is desirable.

The thickness of the tin or tin alloy plating layer on the surface is
If the thickness is less than 0.3 μm, the contact resistance cannot be prevented from deteriorating.
0.3 μm or more is required. The upper limit of the thickness is required to be 3 μm or less since the insertion / extraction property decreases as the thickness increases. When the reflow treatment is performed, a part of the tin or tin alloy plating layer forms a diffusion layer with the intermediate layer, and the thickness of the pure plating layer becomes thin. It is necessary to be 5 μm or more, and preferably 1 μm to 2 μm in consideration of productivity and the like.

Furthermore, in order to obtain a thin film lubricating effect of metal,
The ratio of the thickness of the surface tin or tin alloy plating layer to the thickness of the intermediate layer is 1:
It is preferable to set it in the range of 2-1: 3.

The surface layer is formed by reflow plating. In addition to the formation of the diffusion layer, the intermediate layer promotes diffusion of phosphorus and boron into the surface layer so that predetermined phosphorus and boron are contained in tin or tin alloy plating of the surface layer. That's why. If the diffusion of phosphorus or boron is insufficient only by reflow, it is possible to compensate for this by performing aging, if necessary, for example, at 100 ° C. for 12 hours to diffuse phosphorus.
These phosphorus or boron not only prevent oxidation inside the plating layer but also form a protective film of these oxides on the surface layer. Due to the above effects, characteristics such as solderability and insertion / extraction properties are improved.

As the surface plating layer, in addition to tin, a tin alloy, mainly tin-lead solder plating, or a lead-free solder such as tin-silver or tin-bismuth can be selected.

As the plating solution for the intermediate layer, the basic nickel-phosphorus and nickel-boron alloy plating is performed by using a phosphoric acid or sodium hypophosphite, boraneamine complex based on a bath containing nickel sulfate and nickel chloride. An added bath or the like can be used. The borane amine complex becomes a source for adding boron to the plating film. However, in the present application, in any plating, the composition and conditions of the plating bath can be arbitrarily selected. Other alloying elements are alloyed by adding a required amount of a metal salt such as copper sulfate or the like for copper, tin sulfate or the like for tin, and zinc for zinc or the like. When copper is added, a complexing agent is used because the natural potential of copper is higher than the others. Glycine added as a complexing agent is for co-depositing copper and nickel. It is necessary to select an optimum one depending on the complexing agent and the pH of the plating bath. However, the effects of the present invention are not limited at all by selecting these conditions.

For the tin plating or tin alloy plating of the surface layer, known sulfuric acid-based, methanesulfonic acid-based, phenolsulfonic acid-based plating solutions and the like can be used. After plating, a reflow treatment is performed to grow a nickel-tin diffusion layer, and at the same time, phosphorus and boron contained in the intermediate layer are diffused into the surface layer to improve heat resistance and insertability.

Carbon in the tin plating on the surface layer is present as an inevitable impurity due to the addition of a surfactant.
Increasing the carbon content has an adverse effect on heat resistance, especially solderability. Therefore, it is necessary to set plating conditions so that the carbon content is 0.5% or less.

As a means for further improving the insertability and heat resistance, it is also effective to perform a surface treatment after the plating treatment. One is a phosphate treatment, in which the reflowed or heat-treated material is immersed in a solution containing 0.1 to 2 mol / L of phosphate ions or electrolytically treated using the corresponding sample as an anode, so that the surface of the organic phosphorous is treated. This is a technique for forming a compound or inorganic phosphorus compound film. For example, a method of immersing a test material in a solution composed of a soluble phosphate solution and free phosphoric acid, dissolving a part of tin on the surface with free phosphoric acid, and forming an insoluble phosphate on the surface layer is known. I can take it. However, the means does not limit the effects of the present application. By coating these films with these films, the surface layer of the plating is protected, and the inside is prevented from being oxidized and the like and the heat resistance is improved.

Another method is a sealing treatment or a lubricating treatment. The sealing treatment is a treatment for closing a hole formed on the plating surface, and is effective in improving corrosion resistance and heat resistance. The lubricant treatment is a treatment for applying a lubricating chemical to the surface. These treatments can only improve the heat resistance in a short time and the insertion / extraction of ordinary plating materials,
By using the above plating material, the effect is exhibited,
Heat resistance is improved. In the claims of the present invention, an alloy containing nickel is defined as the intermediate layer.However, the present invention is applicable to the case where an alloy layer containing nickel exists under a surface gold or gold alloy plating layer. There is no problem even if there is another plating layer between the lower part, that is, the copper alloy as the base material, and the present invention is effective in such a case.

[0031]

Next, the effects of the present invention will be specifically described based on examples. The base material has a thickness of 0.
Two types of phosphor bronze of 2 mm (JIS C 5191) and oxygen-free copper of 0.5 mm in thickness (JIS C 5
1020) was used after degreasing and pickling. The plating of the surface layer was evaluated for reflow tin. further,
Evaluations were also made of the above-mentioned plated materials that had been subjected to phosphate treatment, sealing treatment, and lubricant treatment.

Tables 1 to 4 show the plating conditions of the nickel-phosphorus-boron system and the system to which tin, copper and zinc are added. Table 5 shows the conditions for tin plating of the surface layer. Also,
Table 6 shows the thickness of the intermediate layer, the thickness of the diffusion layer, the average particle size of the diffusion layer, and the plating thickness of the surface layer of each plating material. In addition, as a comparative material, one without an intermediate layer, one with 0.5 μm copper as an intermediate layer, one with 2.0 μm nickel as an intermediate layer, and one with Ni-0.01% B alloy as an intermediate layer I also prepared things. It has been confirmed that the content of phosphorus and boron in the tin-plated portion of each material after the reflow treatment is in the range of 0.01 to 1% in the claims.
Table 7 shows the conditions of the phosphate treatment.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

In the evaluation, the evaluation material was evaluated as 1 for heat resistance.
After heating at 55 ° C. for 16 hours, the appearance, the solderability, the presence or absence of thermal peeling, and the change in contact resistance were evaluated. For the evaluation of insertability, the evaluation material was processed into the shape of male pin and female pin as shown in FIG. 1, and the maximum insertion force when inserting the male pin into female pin was evaluated.

The solderability was evaluated by measuring the solder wetting time by a meniscograph method using 25% rosin-ethanol as a flux. The presence or absence of thermal peeling was evaluated by repeatedly bending the plated material at 90 ° C. and visually observing the state of the bent portion. As shown in FIG. 1, the contact resistance was set at 155 ° C.
The contact resistance (electric resistance) before and after heating for 6 hours was evaluated. Table 8 shows the results. From this, it can be seen that, although a part inferior to the comparative material was seen in terms of contact resistance, the overall material was superior to the comparative material.

[0042]

[Table 8]

In the sealing treatment and the lubricating treatment, a commercially available solution for sealing treatment for gold plating was applied and dried with a blower. Table 9 shows the results of the evaluation of the insertability. This indicates that the insertion force of the terminal is superior to the comparative material in any system.

[0044]

[Table 9]

[0045]

As described above, according to the present invention, it is possible to supply a material that satisfies both heat resistance and insertability.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for carrying out an insertion / extraction evaluation test according to the present invention.

[Explanation of symbols]

 1 female pin 2 male pin

Claims (12)

[Claims] 1. A nickel or nickel alloy base layer containing a total of 0.05% to 20% of phosphorus and / or boron on a copper or copper alloy base material, and further electroplated with a tin or tin alloy layer After reflow treatment, the concentration of phosphorus and / or boron in the tin or tin alloy plating layer is reduced to 0.0
A metal material having high heat resistance and aging resistance, which is 1% to 1%. 2. A copper or copper alloy base material is electroplated with a nickel alloy plating intermediate layer containing a total of 0.05% to 20% of phosphorus and / or boron, and further a tin or tin alloy layer plating surface layer. After reflow treatment, the concentration of phosphorus and / or boron in the tin or tin alloy plating layer is reduced to 0.0
A metal material for terminal / connector contacts having improved insertion / extraction characteristics, wherein the metal material is 1% to 1%. 3. The intermediate layer is a nickel alloy containing 0.05 to 20% in total of phosphorus and / or boron and 10 to 60% in total of one or more of Sn, Cu and Zn. The metal material according to claim 1, wherein: 4. The metal material according to claim 1, wherein the thickness of the surface layer is 0.3 μm to 3 μm. 5. The metal material according to claim 1, wherein the thickness of the intermediate layer is 0.5 μm to 3 μm. 6. A copper or copper alloy base material is electroplated with a nickel alloy plating intermediate layer containing a total of 0.05% to 20% of phosphorus and / or boron, and further a tin or tin alloy layer surface layer. After the plating, a reflow treatment (and / or a heat treatment) is performed, and then the phosphorus and / or boron contained in the intermediate layer is diffused to the surface of the tin or tin alloy plating layer. Improved metal material for terminal and connector contacts. 7. A diffusion layer of tin and nickel having a thickness of 1.0
7. The metal material for an electronic component according to claim 6, wherein the metal material has a planar particle size of 1.0 μm or less and a diffusion layer has a planar particle size of 1.0 μm or less. 8. The method according to claim 1, wherein the carbon concentration in the tin or tin alloy plating layer is 0.05 to 0.5%.
The metal material for an electronic component according to claim 4. 9. The method according to claim 1, wherein after the reflow treatment or the heat treatment, the material is immersed in an aqueous solution containing 0.1 to 2 mol / L of phosphate ions or electrolytically treated using the material as an anode in the aqueous solution. 7. The method for producing a metal material for electronic parts according to 6. 10. The metal material for electronic parts according to claim 1, wherein a film of an organic phosphorus compound or an inorganic phosphorus compound is formed after the reflow treatment or the heat treatment. 11. The method according to claim 1, wherein a sealing treatment and a lubricating treatment are performed after the reflow treatment or the heat treatment. 12. A terminal and a connector, wherein the metal material according to claim 1 is used as a contact.