KR102503365B1 - Plating material with excellent heat resistance and its manufacturing method - Google Patents

Abstract

Provided is a Sn-plated material capable of maintaining desired heat resistance even at a high temperature of 175°C and not causing cracks during formation of a contact portion and a manufacturing method thereof.
A first base layer 2 made of Ni or a Ni alloy, an intermediate layer 4 made of a CuSn compound, and a surface layer 5 made of Sn or a Sn alloy are placed on a conductive substrate 1 made of Cu or a Cu alloy in that order. A Sn plating material having a layer, wherein the Sn plating material has a thickness of 0.5 to 10 μm per 20 μm of interface length between the first base layer and the conductive substrate on the surface of the conductive substrate when viewed in cross section in the rolling direction and the plate thickness direction. Sn plating material 10 in which the damaged layer 6 remains in length or in which a plurality of damaged layers 6 exist in a total length of 0.5 to 10 μm per interface length of 20 μm, and its manufacture method and use.

Description

Plating material with excellent heat resistance and its manufacturing method

The present invention relates to a tin (Sn) plating material suitable for vehicle-mounted parts, electric and electronic parts, lead frames, relays, switches, sockets, and the like, and a manufacturing method and use thereof.

Conventionally, copper (Cu) or a copper alloy having excellent electrical conductivity has been used as an electrical contact material. In recent years, the improvement of contact characteristics has progressed, and cases using copper or copper alloy as it is are decreasing. Instead of these conventional materials, various surface-treated materials on copper or copper alloys are being manufactured and used. In particular, as an electrical contact material, a member in which tin or a tin alloy is plated on copper or a copper alloy in an electrical contact portion is widely used.

This plating material is known as a high-performance conductor with excellent conductivity and strength of a conductive substrate and excellent electrical connectivity, corrosion resistance and solderability of a plating layer, and is widely used in various terminals and connectors used in electrical and electronic devices. It is being used. For this plating material, nickel (Ni), cobalt (Co) or the like having a barrier function is usually plated on the substrate in order to prevent diffusion of alloy components of the conductive substrate such as copper into the plating layer.

When this plating material is used as a terminal, an oxide film is formed on the surface of the tin plating layer because tin in the tin plating layer on the surface of the terminal is easily oxidized in a high-temperature environment such as in an automobile engine room. Since this oxide film is brittle, it is destroyed at the time of terminal connection, and the unoxidized tin plating layer underneath it is exposed, and good electrical connection is obtained.

However, as a usage environment of recent electrical contact materials, cases in which they are used under high-temperature environments are increasing. For example, contact materials for sensors in automobile engine rooms are increasingly likely to be used in high-temperature environments such as 100°C to 200°C. For this reason, reliability such as contact characteristics in higher temperatures than the operating temperature assumed for conventional consumer equipment is required. In particular, as a cause that influences the reliability of contact characteristics, it is a problem that the contact resistance in the outermost layer increases due to the diffusion of the conductive substrate component and surface oxidation under high temperatures. Therefore, various investigations have been made on diffusion suppression and oxidation prevention of this conductive substrate component.

In Patent Document 1, a Ni or Ni alloy layer is formed on the surface of a Cu or Cu alloy base material, a Sn or Sn alloy layer having a thickness of 0.25 to 1.5 μm is formed on the outermost surface side, and the Ni or Ni alloy layer and One or more intermediate layers containing Cu and Sn are formed between the Sn or Sn alloy layers, and among these intermediate layers, the Cu content of the intermediate layer in contact with the Sn or Sn alloy layer is 50% by mass or less, and the Ni content is 20 mass%. % or less, and by setting the average crystal grain size to 0.5 to 3.0 μm, a plating material having characteristics such as solderability, whisker resistance and heat resistance reliability and excellent press workability can be obtained.

In Patent Document 2, a surface plating layer composed of a Ni layer, a Cu—Sn alloy layer, and a Sn layer is formed in this order on the surface of a substrate made of Cu or a Cu alloy, and the thickness of the Ni layer is 0.1 to 1.0 μm; By setting the thickness of the Cu-Sn alloy layer to 0.1 to 1.0 μm, the Cu concentration of the Cu-Sn alloy layer to 35 to 75 at%, and the thickness of the Sn layer to 0.5 μm or less, electrical reliability even after a long period of time under a high temperature atmosphere ( Low contact resistance) can be maintained, sulfurous acid gas corrosion resistance is excellent, and plating materials that do not generate cracks even in severe processing are obtained.

In Patent Literature 3, a Ni layer, an intermediate layer composed of a Cu-Sn alloy layer, and a surface layer composed of Sn or Sn alloy are formed in this order on the surface of a substrate made of Cu or Cu alloy without a damaged layer. The Ni layer is epitaxially grown on a substrate, the average crystal grain diameter of the Ni layer is 1 μm or more, the thickness of the Ni layer is 0.1 to 1.0 μm, the thickness of the intermediate layer is 0.2 to 1.0 μm, and the thickness of the surface layer is By setting to 0.5 to 2.0 μm, the barrier property to the base substrate made of Cu or Cu alloy is improved, the diffusion of Cu is more reliably prevented, the heat resistance is improved, and the Sn plating material capable of maintaining stable contact resistance even in a high-temperature environment is is being obtained

Japanese Unexamined Patent Publication 2003-293187 Japanese Laid-open Patent Publication 2004-068026 Japanese Unexamined Patent Publication 2014-122403

In recent years, for example, in vehicle-mounted parts, good electrical connectivity (hereinafter simply referred to as heat resistance) under high temperatures is required with more materials than ever before due to the increase in the amount of current due to the increase in the environmental temperature and the spread of electric vehicles. there is. Also in other uses, an increase in the circuit current density accompanying the increase in the environmental temperature and the miniaturization and high output of parts can be seen, and improvement in heat resistance is also required. Moreover, with the miniaturization of components, better bending workability is requested|required.

In Patent Literatures 1 and 2, a test at 160°C is performed as an index of heat resistance. However, it is not possible to sufficiently meet the heat resistance required in recent years only by clearing this level. For example, in a test at 175°C, it was found that Cu diffused from the conductive substrate reacts with Sn on the surface to form a compound, and Sn disappears on the surface, thereby reducing electrical connectivity.

In the Sn plating material of Patent Document 3, good electrical connectivity can be obtained even after heating at 175°C for 1000 hours, and it has excellent heat resistance. However, since the crystal grain size of the Ni plating layer is larger than before, cracks are likely to occur when the contact portion is formed by bulging or bending. If a cracked part is used in a heat environment, corrosion of the substrate proceeds at the cracked portion of the plating, and there is a risk of impairing electrical connectivity.

In view of the above circumstances, an object of the present invention is to provide a Sn-plated material capable of maintaining desired heat resistance even at a high temperature of 175° C. and not causing cracks during formation of contact portions and a manufacturing method thereof.

The inventors of the present invention conducted various studies so that the above problems can be solved. As a result, the inventors of the present invention intensively researched Sn plating materials suitable for vehicle-mounted parts, electrical and electronic parts, lead frames, relays, switches, sockets, etc., and made Ni or Ni alloys on conductive substrates made of Cu or Cu alloys. A Sn-plated material in which each layer is formed in the order of a first base layer made of a CuSn compound, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or Sn alloy, wherein the Sn plated material is a conductive substrate when viewed in cross section formed in the rolling direction and the plate thickness direction. On the surface of the first base layer and the conductive substrate, a damaged layer with a length of 0.5 to 10 μm per 20 μm of interface length remains, or a total of 0.5 to 10 damaged layers per 20 μm in interface length. It was found that a Sn plating material having both heat resistance and workability can be obtained by existing in a length of μm.

According to the present invention, the following means are provided.

(1) A Sn plating material having each layer in the order of a first base layer made of Ni or a Ni alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or Sn alloy on a conductive substrate made of Cu or a Cu alloy, in the order described above. When the Sn plating material is viewed in cross section in the rolling direction and the plate thickness direction, a damaged layer remains on the surface of the conductive substrate in a length of 0.5 to 10 μm per 20 μm of interface length between the first base layer and the conductive substrate, or , A Sn-plated material characterized in that a plurality of damaged layers are present with a total length of 0.5 to 10 μm per interface length of 20 μm.

(2) The order of a first base layer made of Ni or a Ni alloy, a second base layer made of Cu or a Cu alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or a Sn alloy on a conductive substrate made of Cu or a Cu alloy. As a Sn plating material having each layer, the Sn plating material is 0.5 to 10 μm per 20 μm of interface length between the first base layer and the conductive substrate on the surface of the conductive substrate when viewing the cross section in the rolling direction and the sheet thickness direction. A Sn-plated material characterized in that a damaged layer remains in a length of ㎛ or a plurality of damaged layers exist in a total length of 0.5 to 10 ㎛ per interface length of 20 ㎛.

(3) The Sn-plated material according to (1) or (2), wherein the first base layer has a mixture of a portion having a crystal grain size of 1 μm or more and a portion having a crystal grain size of less than 1 μm.

(4) The Sn plating material according to any one of (1) to (3), wherein the surface layer has a thickness of 0.2 to 5 µm.

(5) The Sn plating material according to any one of (1) to (4), wherein the intermediate layer has a thickness of 0.1 to 1 µm.

(6) The Sn plating material according to any one of (1) to (5), wherein the first base layer has a thickness of 0.1 to 2 µm.

(7) The Sn plating material according to any one of (2) to (6), wherein the second base layer has a thickness of 0 to 0.1 µm.

(8) The Sn-plated material according to any one of (1) to (7), characterized in that the intermediate layer is exposed on the material surface at an area ratio of 0.1 to 60% when subjected to heat treatment at 175°C for 240 hours.

(9) A vehicle-mounted part using the Sn plating material according to any one of (1) to (8).

(10) Electrical and electronic components using the Sn plating material according to any one of (1) to (8).

(11) A method for producing a Sn-plated material in which each layer is formed on a conductive substrate made of Cu or a Cu alloy in the order of a first base layer made of Ni or a Ni alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or a Sn alloy in this order. ,

After forming the first base layer, the second base layer made of Cu or a Cu alloy, and the surface layer in this order on the conductive substrate, the second base layer and the surface layer are formed by reflow treatment, 2 react until the base layer disappears to form the intermediate layer,

The conditions for buffing and pickling of conductive substrates are that the size of the buffing abrasive particles is #1000 to 5000, the immersion time in the pickling solution is 0 to 60 seconds, and the processing rate of the finishing processing conditions is adjusted to 0 to 70% In addition, by controlling the remaining amount of the damaged layer on the surface of the conductive substrate by adjusting the finish heat treatment conditions at 250 to 650 ° C. for 5 seconds to 5 hours as needed, the Sn-plated material is rolled in the rolling direction and the sheet thickness direction When viewing the cross section consisting of, a damaged layer remains on the surface of the conductive substrate with a length of 0.5 to 10 μm per 20 μm of interface length between the first base layer and the conductive substrate, or a plurality of layers per 20 μm of interface length. A method for producing a Sn-plated material, characterized in that the damaged layer of the present in a total length of 0.5 to 10 μm.

(12) The order of a first base layer made of Ni or a Ni alloy, a second base layer made of Cu or a Cu alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or a Sn alloy on a conductive substrate made of Cu or a Cu alloy. As a method for producing a Sn plating material in which each layer is formed,

After forming the first base layer, the second base layer, and the surface layer in this order on the conductive substrate, the second base layer and the surface layer are formed by reflow treatment, and the second base layer is partially To remain, react to form the intermediate layer,

The conditions for buffing and pickling of conductive substrates are that the size of the buffing abrasive particles is #1000 to 5000, the immersion time in the pickling solution is 0 to 60 seconds, and the processing rate of the finishing processing conditions is adjusted to 0 to 70% In addition, by controlling the remaining amount of the damaged layer on the surface of the conductive substrate by adjusting the finish heat treatment conditions at 250 to 650 ° C. for 5 seconds to 5 hours as needed, the Sn-plated material is rolled in the rolling direction and the sheet thickness direction When viewing the cross section consisting of, a damaged layer remains on the surface of the conductive substrate with a length of 0.5 to 10 μm per 20 μm of interface length between the first base layer and the conductive substrate, or a plurality of layers per 20 μm of interface length. A method for producing a Sn-plated material, characterized in that the damaged layer of the present in a total length of 0.5 to 10 μm.

According to the Sn plating material of the present invention, diffusion of the base material Cu from the conductive base material to the surface layer is suppressed and good heat resistance can be obtained by partially remaining the damaged layer on the surface of the conductive base material. In addition, cracking of the contact portion formed by bending or bulging can be suppressed.

The above and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.

1 is a cross-sectional view of one embodiment of the Sn plating material of the present invention.
2 is a cross-sectional view of another embodiment of the Sn plating material of the present invention.
3 is a cross-sectional view of a bulging processing method performed in an example.
4 is a cross-sectional view of a Sn plating material subjected to bulging processing performed in Examples.
5 is a conceptual diagram schematically showing a state of aging deterioration.

A preferred embodiment of the Sn plating material of the present invention will be described in detail. As shown in FIG. 1, the Sn plating material 10 of this embodiment consists of the 1st base layer 2 which consists of Ni or a Ni alloy, and the CuSn compound on the conductive base material 1 which consists of Cu or Cu alloy. It is the structure in which each layer was formed in order of the intermediate|middle layer 4 and the surface layer 5 which consists of Sn or Sn alloy. In some cases, as shown in FIG. 2 , a second base layer 3 made of Cu or a Cu alloy may be formed between the first base layer 2 and the intermediate layer 4 . In either case, the damaged layer 6 remains between the first base layer 2 and the conductive substrate 1 with the above predetermined length.

By partially leaving the damaged layer on the surface of the conductive substrate, a first base layer with a small crystal grain size is formed on the conductive substrate at that portion, and a first base layer with a large crystal grain size is formed on the portion from which the damaged layer is removed. is formed A portion with a small crystal grain size contributes to improvement in workability, and a large portion contributes to improvement in heat resistance by suppressing the diffusion of substrate component Cu from the conductive substrate to the surface layer. Directly above the portion of the first base layer having a small crystal grain size, the surface layer disappears or decreases due to diffusion of the base material Cu from the conductive substrate, but the surface layer remaining immediately above the portion of the large crystal grain size results in a generally good condition. Heat resistance is obtained. Also, when maintenance is performed after use in a high-temperature environment such as a vehicle-mounted terminal, the insertion force at the time of removal and insertion is lower than at the beginning due to the effect of the intermediate layer grown directly above the portion of the first base layer having a small crystal grain size.

The shape of the conductive substrate 1 is not particularly limited, and examples thereof include a plate, a strip, foil, and a wire. Below, although a plate material and a strip material are demonstrated as an embodiment, the shape is not limited to these. For the conductive substrate 1, Cu or a Cu alloy is used. Although the type of Cu or Cu alloy is not particularly limited, it may be appropriately selected according to the requirements of the strength, electrical conductivity, and the like of the application to be used.

As an example of a copper alloy that can be used for the conductive substrate 1, "C14410 (Cu-0.15Sn, manufactured by Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC3)", "C19400 (Cu- Fe alloy material, Cu-2.3Fe-0.03P-0.15Zn)”, “C18045 (Cu-0.3Cr-0.25Sn-0.5Zn, manufactured by Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC64T)”, “C64770 (Cu -Ni-Si alloy material, manufactured by Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC-97)", "C64775 (Cu-Ni-Si alloy material, manufactured by Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC-820) 」, etc. can be used. (On the other hand, the unit of the number in front of each element of the copper alloy indicates the mass% in the copper alloy.) In addition, TPC (tough pitch copper), OFC (oxygen-free copper), phosphor bronze, brass (for example, 70 mass% Cu-30% by mass Zn. Abbreviated as 7/3 brass.) and the like can also be used. From the viewpoint of improving conductivity and heat dissipation, it is preferable to use a copper alloy having a conductivity of 5% IACS or more. On the other hand, the "substrate component" of the present invention when handling copper alloy as the conductive base material 1 shall indicate copper as a base metal. The thickness of the conductive substrate 1 is not particularly limited, but is usually 0.05 to 2.00 mm, preferably 0.1 to 1.2 mm.

The first base layer 2 is made of, for example, Ni, and functions as a diffusion barrier layer that suppresses diffusion of the substrate component Cu from the conductive substrate 1 to the surface layer 5. The thickness of the first base layer 2 is preferably 0.1 to 2 μm, more preferably 0.2 to 1 μm. If it is too thin, the effect of suppressing the diffusion of the substrate component Cu is reduced, and the heat resistance of the Sn plating material 10 is lowered. Moreover, when it is too thick, workability will fall and there exists a possibility that a crack may arise. In addition, the 1st base layer 2 may be formed from Ni alloy, For example, Ni-P, Ni-Cu, Ni-Cr, Ni-Sn, Ni-Zn, Ni-Fe etc. can be used.

The first base layer 2 formed on the conductive substrate 1 by, for example, a plating method is oriented to the conductive substrate 1 at the portion where the damaged layer 6 is removed, and Ni crystal grains grow, thereby increasing conductivity. A crystal grain diameter equivalent to that of the substrate (1) is obtained. Since the crystal grain diameter of Cu or Cu alloy is generally about 1 to 30 μm, the crystal grain diameter of the first base layer 2 (Ni) formed on the portion where the damaged layer 6 is removed is mostly 1 It is more than μm. In contrast, in the portion where the damaged layer 6 remains, the crystal grain diameter of the first base layer 2 near the surface of the conductive base material 6 is extremely small compared to the original crystal grain diameter of the base material. The first base layer 2 (Ni) obtained above has a small crystal grain diameter of 0.01 μm or more and less than 1 μm.

The middle layer 4 is formed by sequentially forming the second base layer 3 and the surface layer 5 on the first base layer 2 and then reflowing the second base layer 3 and the surface layer 5. It is obtained by this reaction and consists mainly of Cu ₃ Sn and Cu ₆ Sn ₅ . Being mainly composed of Cu ₃ Sn and Cu ₆ Sn ₅ means that Cu ₃ Sn and Cu ₆ Sn ₅ are constituted by 50% by mass or more. The intermediate layer 4 acts as a diffusion barrier layer preventing a reaction between the surface layer 5 and the first base layer 2 . It is preferable that it is 0.1-1 micrometer, and, as for the thickness of the intermediate|middle layer 4, it is more preferable that it is 0.2-0.8 micrometer. If it is too thin, the effect as a diffusion barrier layer becomes small, the reaction between the surface layer 5 and the first base layer 2 proceeds, and the heat resistance of the Sn-plated material 10 decreases. Moreover, when it is too thick, workability will fall and there exists a possibility that a crack may arise.

The surface layer 5 is necessary to secure the electrical connectivity of the contacts. It is preferable that it is 0.2-5 micrometers, and, as for the thickness of the surface layer 5, it is more preferable that it is 0.3-2 micrometers. When too thin, Sn reacts with Cu diffused from the conductive base material 1 and disappears under high temperature, and electrical connectivity is impaired. If it is too thick, the influence of the hard intermediate layer 4 near the surface is diminished, and the influence of the surface layer 5, which is soft Sn or Sn alloy, increases. ) increases, and the work load increases. In particular, by setting it as 2 micrometers or less in thickness, insertion force can be reduced remarkably. The surface layer 5 may be formed of Sn alloy, and for example, Sn-Cu, Sn-Bi, Sn-Pb, Sn-Ag, Sn-Sb, Sn-In, etc. can be used.

Between the 1st base layer 2 and the intermediate layer 4, you may form the 2nd base layer 3. The second base layer 3 is shown in FIG. 1 when the second base layer 3, the intermediate layer 4, and the surface layer 5 are sequentially formed on the first base layer 2 and then subjected to reflow treatment. As shown, all of the second base layer 3 is used for the formation of the intermediate layer 4 and may be lost, or as shown in FIG. 2, part of the second base layer 3 is not used, The second base layer 3 not used in the formation of the intermediate layer 4 may remain. The thickness of the remaining second base layer 3 is preferably 0 to 0.1 μm, and more preferably 0 to 0.05 μm. Like the intermediate layer 4, the second base layer 3 acts as a diffusion barrier layer that prevents the reaction between the surface layer 5 and the first base layer 2. However, when it is too thick, it reacts with the surface layer 5 on the surface under high temperature, and causes a decrease in heat resistance. As a Cu alloy used as the 2nd base layer 3, Cu-Ni, Cu-Sn, etc. are mentioned, for example.

In this embodiment, part of the damaged layer 6 remains on the surface of the conductive substrate 1 . The damaged layer 6 itself has been conventionally known. Describing the process-damaged layer 6, it is a layer formed under the influence of heat or force generated during the buffing process or rolling process (machining), the surrounding atmosphere, the nature of the new metal surface, and the like, inside the metal substrate. shows a finer structure than the crystalline structure of Fine crystals and amorphous portions are mixed in the affected layer 6, and the size of the crystal grains present in the affected layer 6 is 1 μm or less. The altered layer is composed of a beilby layer (upper layer) and a plastic deformation layer (lower layer). Here, the Beilby layer is made of an extremely fine crystalline aggregate structure or an amorphous structure. On the other hand, the plastically deformed layer is composed of a non-uniform crystal texture with many distortions, and the size of its crystal grains is approximately intermediate in size between the crystal grains of the Beilby layer and the crystal grains inside the metal substrate.

Since the damaged layer is a thermally unstable structure, it is changed into a thermally stable atomic arrangement due to atomic diffusion by heat during heat treatment and is reduced. By dissolving the surface of the conductive substrate, a part or all of the damaged layer can be removed. The Sn plating material 10 of this embodiment has an interface length between the first base layer 2 and the conductive substrate 1 on the surface of the conductive substrate 1 when a cross section formed in the rolling direction and the sheet thickness direction is viewed. Per 20 μm, the damaged layer 6 remains in a length of 0.5 to 10 μm, or a plurality of damaged layers 6 exist in a total length of 0.5 to 10 μm per 20 μm of interface length, It is preferable that there exists, and it is more preferable that one or several damaged layers 6 remain 1-5 micrometers in total. When the length of the damaged layer 6 is too short, most of the crystal grain diameters of the first base layer 2 (Ni) are large, and cracks occur at the contact portion due to a decrease in workability, resulting in damage to electrical connectivity. There is a risk of becoming Conversely, when the length of the damaged layer 6 is too long, most of the crystal grain diameters of the first base layer 2 (Ni) are small, and the substrate component Cu diffuses from the conductive substrate 1 to the surface layer 5. As a result, there is a possibility that the heat resistance may be lowered.

In this embodiment, since the Ni crystal grain size of the first base layer 2 is small immediately above the portion where the damaged layer 6 remains, the substrate from the conductive substrate 1 to the surface layer 5 Diffusion of component Cu proceeds, and the intermediate layer 4 tends to grow. On the other hand, in the portion where the damaged layer 6 has been removed, the crystal grain size of Ni in the first base layer 2 is large, and the diffusion of the substrate component Cu from the conductive substrate 1 to the surface layer 5 is suppressed. As a result, it is difficult for the intermediate layer 4 to grow. For this reason, when this embodiment is used under high temperature, a difference arises in the growth of the intermediate layer 4 in the material, and the intermediate layer 4 is partially exposed on the surface of the Sn plating material 10 (see Fig. 5). When the intermediate layer 4 is partially exposed after use under high temperature, for example, when removing and plugging in and out of a vehicle-mounted terminal for maintenance or the like, the insertion force is lower than in the initial stage, and the work load is reduced. When 0.1 to 60% of the intermediate layer 4 is exposed on the surface of the Sn plating material 10 after heating at 175° C. for 240 hours, insertion force lower than the initial stage and good electrical connectivity can be simultaneously obtained. In order to simultaneously obtain a lower insertion force than the initial one and good electrical connectivity, the area ratio of the exposed intermediate layer 4 is preferably 0.1 to 60%, more preferably 0.5 to 40%, and 1 to 30%. more preferable If the exposed area ratio of the intermediate layer 4 is too small, low insertion force cannot be obtained, and if too large, good electrical connectivity cannot be obtained.

Next, the manufacturing method of the Sn plating material 10 of this embodiment is demonstrated. In the Sn plating material 10 of the present embodiment, usually, Ni or Ni alloy plating → Cu or Cu alloy plating → Sn or Sn alloy plating is performed in order on the conductive substrate 1 made of Cu or Cu alloy, and then It is manufactured by performing a reflow process. Before and after each step, degreasing, pickling, washing with water, and drying may be appropriately performed. In the manufacturing method of this embodiment, it is important to leave a part of the damaged layer 6 on the surface of the conductive substrate 1 before Ni or Ni alloy plating. In the production method of the present embodiment, the conditions of buffing and pickling of the conductive substrate are adjusted, and the processing rate of the finishing conditions is adjusted to 0 to 70%, and the remaining amount of the damaged layer 6 is controlled. In addition, if necessary, you may carry out the finishing heat treatment conditions in the range of 250-650 degreeC for 5 seconds - 5 hours. The manufacturing method of the present embodiment achieves improvement in material properties by appropriately adjusting each process condition while using the same number of steps as the conventional one.

<Conductive material>

The conductive substrate 1 is not particularly limited as long as it is Cu or a Cu alloy, and may be appropriately selected according to requirements such as strength and conductivity of the application to be used. The damaged layer 6 on the surface of the conductive substrate 1 is determined by the amount of buffing in the buffing and pickling process after heat treatment, the amount of surface dissolution in the pickling solution, or the processing rate of finishing, and also finishing as necessary. It can be controlled by adjusting the annealing conditions. The amount of buffing and the amount of surface dissolution in the pickling solution can be controlled by the size of the buffing grains, the composition of the pickling solution, the immersion time in the pickling solution, and the like. Specifically, the size of the buffing abrasive grains is controlled to #1000 to 5000, and the immersion time in the pickling solution is controlled to 0 to 60 seconds. When the size of the buff abrasive grain is smaller than #1000, the surface of the conductive substrate 1 after polishing is rough, and defects such as pinholes are likely to occur in the plating film, and when the size is larger than #5000, the effect of buff polishing is obtained It gets difficult. Also, when the immersion time in the pickling liquid is longer than 60 seconds, the surface of the conductive substrate 1 may be acid-baked, and a normal plating film may not be obtained. An immersion time of 0 second means that pickling was not performed. As the pickling solution, a sulfuric acid-based aqueous solution, a hydrofluoric acid-based aqueous solution, a nitric acid-based aqueous solution, a phosphoric acid-based aqueous solution, or the like can be used. In addition, finishing can be performed at a processing rate of 0 to 70%, for example. Here, 0% of finishing means that no finishing is performed. When the finishing processing rate exceeds 70%, the bending workability of the obtained Sn-plated material 10 is remarkably reduced. In the case of performing finish annealing, for example, it can be carried out at 250 to 650°C for 5 seconds to 5 hours. If the temperature is lower than this condition or for a shorter time, it is difficult to obtain the effect of finish annealing, and there is a fear that the remaining amount of the damaged layer may be greater than the specified range. In addition, at high temperature or for a long time, there is a possibility that the residual amount of the damaged layer is less than the specified range and the material strength of the Sn-plated material 10 is remarkably reduced.

<Ni or Ni alloy plating forming the first base layer 2>

Ni or Ni alloy may be plated by a general method. As a plating bath, a sulfamine bath, a Watt bath, a sulfuric acid bath, etc. can be used, for example. The plating conditions may be plating at a bath temperature of 20 to 60°C and a current density of 1 to 30 A/dm 2 .

<Cu or Cu alloy plating forming the second base layer 3>

What is necessary is just to plate Cu or Cu alloy by a general method. As a plating bath, a sulfuric acid bath or a cyan bath can be used, for example. The plating conditions may be plating at a bath temperature of 20 to 60°C and a current density of 1 to 30 A/dm 2 .

<Sn or Sn alloy plating forming the surface layer 5>

What is necessary is just to plate Sn or Sn alloy by a general method. As a plating bath, a sulfuric acid bath etc. can be used, for example. The plating conditions may be plating at a bath temperature of 10 to 40°C and a current density of 1 to 30 A/dm 2 .

<Reflow processing>

The reflow treatment after forming up to the surface layer 5 can be performed by a general method. For example, the material may be passed through a furnace set at 400 to 800°C, heated for 5 to 20 seconds, and then cooled. By the reflow process, the second base layer 3 and the surface layer 5 react, and the intermediate layer 4 is formed.

Therefore, when the middle layer 4 is formed by reacting the second base layer 3 and the surface layer 5 by the reflow process until the second base layer 3 disappears, as shown in FIG. There is no second base layer between the first base layer 2 and the intermediate layer 4.

Further, when the middle layer 4 is formed by reacting the second base layer 3 and the surface layer 5 by the reflow process so that a part of the second base layer 3 remains, as shown in FIG. 2, the first base layer 5 is formed. A second base layer 3 is formed between the layer 2 and the intermediate layer 4.

The Sn plating material 10 of this embodiment suppresses the diffusion of substrate component Cu from the conductive substrate 1 to the surface layer 5 by partially leaving the damaged layer 6 on the surface of the conductive substrate 1, , good heat resistance can be obtained. In addition, cracking of the contact portion formed by bending or bulging can be suppressed.

(Use of Sn plating material 10)

The Sn plating material 10 of this embodiment is especially excellent in heat resistance (electrical connectivity) under high temperature. For this reason, the Sn plating material 10 of this embodiment is suitable for electric and electronic components, such as terminals, connectors, and lead frames, in addition to vehicle-mounted components such as small terminals and high-voltage and large-current terminals.

[Example]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

After buffing, pickling, finishing machining, and finish annealing were performed on a copper alloy base material (Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC-97) with a sheet thickness of 0.25 mm, electrolytic degreasing and pickling were performed, Ni plating, Cu Plating and Sn plating were performed in this order, and reflow treatment was performed by passing through a furnace maintained at 700°C for 5 to 10 seconds. Each plating condition is shown in Table 1. On the other hand, with respect to buff polishing, pickling, finish processing, and finish annealing, the amount of the damaged layer remaining on the cross section of the base material after the reflow treatment was controlled so as to fall within a prescribed range. The amount of buffing was adjusted by setting the size of the buffing grains in the range of #1000 to 5000. The amount of surface dissolution was adjusted by setting the immersion time in the mixed aqueous solution of sulfuric acid and hydrogen peroxide as a pickling solution to the range of 0 to 60 seconds. In addition, the conditions were adjusted such that the working rate of the finishing was in the range of 0 to 70%, and the finishing annealing was 5 seconds to 5 hours at 250 to 650°C. The residual amount of the damaged layer was measured by the method described later.

Under these conditions, as shown in Table 2 described later, as examples falling within the scope of the present invention, Sn plating materials 10 of Inventive Examples 1 to 7 having different layer thickness configurations were produced.

In addition, as a comparative example, a Sn-plated material in which the residual amount of the damaged layer deviates from the provisions of the present invention was also produced (Comparative Examples 1, 2, 3, and 4).

Here, Comparative Example 1 corresponds to the case where there is no damaged layer in Patent Document 3 (Examples 1 to 6 of Patent Document 3), and after buffing in a buffing and pickling process, immersed in a pickling solution for 60 seconds, It was manufactured with the thing which did not perform finish processing and finish annealing. Comparative Example 4 corresponds to the case where the damaged layer remains on the entire surface of the conductive substrate 1 (Comparative Example 1 of Patent Document 3), and finish processing is performed after buffing and pickling by 70%, followed by finishing. It was manufactured with the thing which did not perform annealing. Comparative examples 2 and 3 are examples in which a part of the damaged layer remains on the conductive substrate and the amount of the damaged layer is adjusted so that the remaining amount does not fall within the scope of the present invention. In Comparative Example 2, finish processing was performed after buffing and pickling, and finish annealing was performed at 675° C. for 2 hours, which is higher than the temperature specified in the present invention, and the residual amount of the damaged layer was less than the range specified in the present invention. doing it small In Comparative Example 3, finishing processing was performed after buffing and pickling, and finish annealing was performed at 225° C. for 2 hours, which is lower than the temperature specified in the present invention, and the remaining amount of the damaged layer was within the range specified in the present invention. doing more

[Cathode electrolytic degreasing]

Degreasing solution: NaOH　60g/liter

Degreasing conditions: 2.5 A/dm2, temperature 60°C, degreasing time 60 seconds

[Acid washing]

Pickling solution: 10% sulfuric acid

Pickling conditions: immersion for 30 seconds, room temperature

The following evaluation was performed about the test material manufactured in this way.

(Measurement of layer thickness of Sn plating material)

The layer thickness of each layer of the Sn plating material produced above was measured by the constant current melting method described in 10 of JIS　H　8501.

(Tissue observation-residual amount of damaged layer)

A cross section formed in the rolling direction and the plate thickness direction of the Sn plating material 10 produced above was observed by FIB-SIM (focused ion beam-scanning ion microscope), and the remaining surface of the conductive substrate 1 The length (residual amount) of the damaged layer 6 was measured. Observation was performed at a magnification of 10000 to 50000 times. For the measurement, with respect to the interface between the first base layer 2 and the conductive substrate 1, the range including the interface length of 20 μm is set as one field of view, and the damaged layer 6 for three fields of view so that the field of view ranges do not overlap. After measuring the interface length of this remaining part, the average value was used as the measurement result. Alternatively, it was confirmed that a plurality of damaged layers 6 were present with a total length of 0.5 to 10 µm per 20 µm of interface length. The position of the interface between the first base layer 2 and the conductive substrate 1 was determined by using elemental mapping using Auger electron spectroscopy analysis accompanying FIB. Moreover, it was judged that the damaged layer 6 was removed in the part where the first base layer 2 immediately above was oriented to the conductive base material 1 and the crystal grain boundary of Ni coincided with the grain boundary of Cu. On the other hand, it was judged that the damaged layer 6 remained in a portion where the crystal grain size of Ni in the first base layer 2 was smaller than the crystal grain boundary of Cu in the conductive substrate 1.

(Heat resistance under high temperature)

The amount of Sn remaining after heating at 160°C for 1000 hours (heat resistance at 160°C) and the amount of Sn remaining after heating at 175°C for 240 hours (heat resistance at 175°C) were measured by the constant current test method described in 10 of JIS　H　8501, respectively. What was evaluated as remaining even a little was made into A (good), and what was evaluated as not remaining at all was made into D (defective).

Fig. 5 schematically shows a state of aging deterioration due to the high temperature (for example, a state left at 150°C for 1000 hours). In FIG. 5, the middle layer 4 and the surface layer 5 thereon remain in the portion where the damaged layer 6 does not exist, but the middle layer 4 is thick right above the damaged layer 6 and the surface layer (5) has almost disappeared.

(Bulging workability)

The Sn plating material 10 produced above was subjected to bulging processing, and those in which plating cracks did not occur after processing were set to A (good) and those that occurred were set to D (defect). For determination of plating cracking, the surface of the bulging part after processing was observed with an optical microscope at a magnification of 50 to 500, and it was judged that cracking occurred when the base material was exposed. 3 is a schematic cross-sectional view of the bulging processing method and the bulging processed Sn plating material 10. In the bulging process, the fixed Sn-plated material 10 prepared above was deformed and processed by pressing a jig made of a hemisphere of 0.5 mmR to the tip. In the figure, O represents the center of the hemisphere at the tip of the jig used for the bulging process. 4 is a schematic cross-sectional view of the Sn plating material 10 after bulging. In the drawing, O represents the center of the hemisphere of the bulging part.

(Exposure area ratio of intermediate layer (CuSn compound layer) on the surface of Sn plating material after high-temperature heating)

After heating at 175°C for 240 hours, the surface of the Sn plating material 10 prepared above was observed by SEM at 1000 times, and the area ratio of the portion where the intermediate layer 4 was exposed was determined by image analysis. The presence or absence of exposure of the intermediate layer 4 was determined by using secondary electron image observation, reflection electron image observation, and EDX elemental mapping attached to the SEM in combination. A (excellent) for exposure area ratio of 1 to 30%, 0.5% or more and less than 1%, or greater than 30% and less than 40% as B (good), 0.1% or more and less than 0.5%, or greater than 40% and 60 What was less than % was C (possible), less than 0.1%, or greater than 60% was made D (defective).

In Table 2, the coating thickness (layer thickness) of each layer of the Sn plating material 10 produced above, the remaining amount (length) of the damaged layer, and the characteristics were collectively shown.

Here, in Table 2, the column described as "Ni" in the column described as "layer thickness (μm)" represents the thickness of the first base layer 2, and the column described as "Cu" represents the thickness of the second base layer 3 Indicates the thickness, the column described as "CuSn" represents the thickness of the intermediate layer 4, and the column described as "Sn" represents the thickness of the surface layer 5. In these invention examples, when the "Cu" layer, that is, the second base layer 3 is 0 μm, it is the embodiment shown in FIG. 1, and the "Cu" layer, that is, the second base layer 3 is 0 μm. Otherwise, it is an embodiment shown in FIG. 2 .

In Table 2, inventive examples 1 to 7 satisfying the conditions of the present invention were all excellent in heat resistance and bulging workability.

On the other hand, in Comparative Examples 1 to 4, several evaluations of heat resistance and bulging workability were inferior. In Comparative Examples 1 and 2, in which the residual amount of the damaged layer was smaller than the range specified in the present invention, the bulging workability was poor, and in Comparative Example 1, the exposed area ratio of the middle layer 4 after heating at 175°C for 240 hours was very high. got smaller Further, in Comparative Examples 3 and 4, in which the residual amount of the damaged layer was greater than the range specified in the present invention, the heat resistance in heating at 175°C for 240 hours was inferior, and the exposed area ratio of the middle layer 4 after heating was very low. and the surface layer 5 hardly remained.

From the above, it was confirmed that the Sn plating material satisfying the conditions of the present invention exhibits excellent characteristics.

Although the present invention has been described with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified, and interpret it broadly without going against the spirit and scope of the invention shown in the appended claims. I think it is natural to be

This application claims the priority based on Japanese Patent Application No. 2015-172147 for which a patent application was filed in Japan on September 1, 2015, and this takes in the content as a part of description of this specification with reference here.

1: conductive substrate 2: first base layer
3: second base layer 4: middle layer
5: surface layer 6: altered layer
10: Sn plating material

Claims (12)

A Sn-plated material having each layer in the order of a first base layer made of Ni or a Ni alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or a Sn alloy on a conductive substrate made of Cu or a Cu alloy, the Sn plated material When viewing a cross section in the rolling direction and the sheet thickness direction, a damaged layer remains on the surface of the conductive substrate in a length of 0.5 to 10 μm per 20 μm of interface length between the first base layer and the conductive substrate, or the interface length A Sn plating material characterized in that a plurality of damaged layers exist with a total length of 0.5 to 10 μm per 20 μm. On a conductive substrate made of Cu or a Cu alloy, each layer in the order of a first base layer made of Ni or a Ni alloy, a second base layer made of Cu or a Cu alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or Sn alloy A Sn plating material having a length of 0.5 to 10 μm per 20 μm of interface length between the first base layer and the conductive substrate on the surface of the conductive substrate when viewed in cross section in the rolling direction and the plate thickness direction. A Sn-plated material characterized in that a furnace damaged layer remains or a plurality of damaged layers exist with a total length of 0.5 to 10 μm per interface length of 20 μm. According to claim 1 or 2,
Sn-plated material characterized in that the first base layer has a mixture of a portion having a crystal grain diameter of 1 μm or more and a portion having a crystal grain diameter of less than 1 μm. According to claim 1 or 2,
Sn plating material, characterized in that the thickness of the surface layer is 0.2 ~ 5㎛. According to claim 1 or 2,
Sn plating material, characterized in that the thickness of the intermediate layer is 0.1 ~ 1㎛. According to claim 1 or 2,
Sn plating material, characterized in that the thickness of the first base layer is 0.1 ~ 2㎛. According to claim 2,
Sn plating material, characterized in that the thickness of the second base layer is 0 ~ 0.1㎛. According to claim 1 or 2,
A Sn-plated material characterized in that, when subjected to heat treatment at 175° C. for 240 hours, the intermediate layer is exposed at an area ratio of 0.1 to 60% on the surface of the material. A vehicle-mounted part using the Sn plating material according to claim 1 or 2. An electrical and electronic component using the Sn plating material according to claim 1 or 2. A method for producing a Sn-plated material in which each layer is formed on a conductive substrate made of Cu or Cu alloy in the order of a first base layer made of Ni or a Ni alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or a Sn alloy in this order,
After forming the first base layer, the second base layer made of Cu or a Cu alloy, and the surface layer in this order on the conductive substrate, the second base layer and the surface layer are formed by reflow treatment, 2 react until the base layer disappears to form the intermediate layer,
The conditions for buffing and pickling of conductive substrates are that the size of the buffing abrasive particles is #1000 to 5000, the immersion time in the pickling solution is 0 to 60 seconds, and the processing rate of the finishing processing conditions is adjusted to 0 to 70% In addition, by controlling the residual amount of the damaged layer on the surface of the conductive substrate by adjusting the finish heat treatment conditions at 250 to 650 ° C. for 5 seconds to 5 hours, as necessary, the Sn plating material is formed in the rolling direction and the plate thickness direction. When viewing the cross section, a process-damaged layer remains on the surface of the conductive substrate in a length of 0.5 to 10 µm per 20 µm of interface length between the first base layer and the conductive substrate, or a plurality of processes per 20 µm of interface length. A method for producing a Sn-plated material, characterized in that the altered layer is present in a total length of 0.5 to 10 μm. On a conductive substrate made of Cu or a Cu alloy, each layer in the order of a first base layer made of Ni or a Ni alloy, a second base layer made of Cu or a Cu alloy, an intermediate layer made of a CuSn compound, and a surface layer made of Sn or Sn alloy As a manufacturing method of the formed Sn plating material,
After forming the first base layer, the second base layer, and the surface layer in this order on the conductive substrate, the second base layer and the surface layer are formed by reflow treatment, and the second base layer is partially To remain, react to form the intermediate layer,
The conditions for buffing and pickling of conductive substrates are that the size of the buffing abrasive particles is #1000 to 5000, the immersion time in the pickling solution is 0 to 60 seconds, and the processing rate of the finishing processing conditions is adjusted to 0 to 70% In addition, by controlling the remaining amount of the damaged layer on the surface of the conductive substrate by adjusting the finish heat treatment conditions at 250 to 650 ° C. for 5 seconds to 5 hours as needed, the Sn plating material is formed in the rolling direction and the plate thickness direction When viewing the cross section, a process-damaged layer remains on the surface of the conductive substrate in a length of 0.5 to 10 µm per 20 µm of interface length between the first base layer and the conductive substrate, or a plurality of processes per 20 µm of interface length. A method for producing a Sn-plated material, characterized in that the altered layer is present in a total length of 0.5 to 10 μm.

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