JP6219553B2 - Plating material excellent in heat resistance and method for producing the same - Google Patents

Description

  The present invention relates to a tin (Sn) plating material suitable for in-vehicle components, electrical / electronic components, 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 the electrical contact material. In recent years, contact characteristics have been improved, and the number of cases in which copper or a copper alloy is used as it is is decreasing. Instead of such conventional materials, various surface-treated materials on copper or copper alloys are 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 is widely used.

  This plating material is known as a high-performance conductor with excellent conductivity and strength of conductive substrates and excellent electrical connectivity, corrosion resistance and solderability of plating layers. Widely used for various terminals and connectors used. This plating material is usually made of nickel (Ni) or cobalt (Co) having a barrier function on the base material to prevent the alloy component of the conductive base material such as copper from diffusing into the plating layer. Plated.

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

  However, in recent years, there are many cases where electrical contact materials are used in high temperature environments. For example, a sensor contact material in an engine room of an automobile is likely to be used in a high temperature environment such as 100 ° C. to 200 ° C. For this reason, reliability such as contact characteristics at a temperature higher than the operating temperature assumed in conventional consumer devices is required. In particular, as a cause that affects the reliability of the contact characteristics, there is a problem that the contact resistance in the outermost layer is increased due to diffusion and surface oxidation of the conductive base material component at high temperatures. Therefore, various studies have been made on diffusion suppression and oxidation prevention of the conductive base material component.

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

  In Patent Document 2, a Ni plating layer, a Cu—Sn alloy layer, and a surface plating layer consisting of a Sn layer are formed in this order on the surface of a base material made of Cu or Cu alloy, and the thickness of the Ni layer is 0.1 to 1.0 μm, the thickness of the Cu—Sn alloy layer is 0.1 to 1.0 μm, the Cu concentration of the Cu—Sn alloy layer is 35 to 75 at%, and the thickness of the Sn layer is 0.5 μm or less. As a result, a plating material that can maintain electrical reliability (low contact resistance) even after a long period of time in a high-temperature atmosphere, has excellent resistance to sulfurous acid gas corrosion, and does not generate cracks in severe processing has been obtained.

  In Patent Document 3, a Ni layer, an intermediate layer made of a Cu-Sn alloy layer, and a surface layer made of Sn or Sn alloy are formed in this order on the surface of a base material made of Cu or Cu alloy without a work-affected layer. . The Ni layer is epitaxially grown on the substrate, the Ni layer has an average crystal grain size of 1 μm or more, the Ni layer has a thickness of 0.1 to 1.0 μm, and the intermediate layer has a thickness of 0.2 to 0.2 μm. By making the thickness of the surface layer 0.5 to 2.0 μm by 1.0 μm, the barrier property to the base substrate made of Cu or Cu alloy is improved, and the diffusion of Cu is more reliably prevented and the heat resistance is improved. The Sn plating material which can improve stable and can maintain the stable contact resistance also in a high temperature environment is obtained.

JP 2003-293187 A JP2004-0668026 JP 2014-122403 A

  In recent years, for example, in in-vehicle parts, due to the increase in the amount of current due to the increase in the environmental temperature and the spread of electric driving vehicles, the material has better electrical connectivity at higher temperatures (hereinafter simply referred to as heat resistance) than ever before. It has been demanded. In other applications as well, an increase in circuit current density has been observed as the environmental temperature is increased, and the size and output of parts are reduced, so that improvement in heat resistance is also required. Further, with the miniaturization of parts, better bending workability is required.

  In Patent Documents 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 recently required heat resistance only by clearing this level. For example, in a test at 175 ° C., it has been found that Cu diffused from the conductive base material reacts with Sn on the surface to form a compound, and Sn on the surface disappears, resulting in a decrease in electrical connectivity.

  In the Sn plating material of patent document 3, the favorable electrical connection property is obtained even after a 175 degreeC and 1000-hour heating, and it has the outstanding 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 overhanging or bending. When a cracked part is used in a thermal environment, the corrosion of the base material proceeds at the plating cracked portion, which may impair electrical connectivity.

  In view of the above circumstances, an object of the present invention is to provide a Sn plating material that can maintain desired heat resistance even at a high temperature of 175 ° C. and that does not cause cracks at the time of contact portion formation, and a method for manufacturing the same. is there.

In order to solve the above problems, the present inventors have made various studies. As a result, the present inventors have earnestly studied Sn plating materials suitable for in-vehicle components, electrical and electronic components, lead frames, relays, switches, sockets, etc., and are manufactured by rolling a metal material in one direction. A Sn plating material in which each layer is formed in the order of a first underlayer made of Ni or Ni alloy, an intermediate layer made of CuSn compound, and a surface layer made of Sn or Sn alloy on a conductive base material made of Cu or Cu alloy. The Sn plating material extends between the first underlayer and the conductive substrate on the surface of the conductive substrate when the cross section formed by the rolling direction and the plate thickness direction of the conductive substrate is viewed. the interface length per 20 [mu] m in the direction of standing, or to leave the damaged layer by the length of 0.5 to 10 [mu] m, the interface length per 20 [mu] m, of 0.5 to 10 [mu] m a plurality of work-affected layer in total By making it exist in length, It found that Sn-plated material having both sexual and processability can be obtained.

According to the present invention, the following means are provided.
(1) It is manufactured by rolling a metal material in one direction, on a conductive base material made of Cu or Cu alloy, a first underlayer made of Ni or Ni alloy, an intermediate layer made of CuSn compound, Sn or Sn alloy The Sn plating material having each layer in the order of the surface layer, the Sn plating material, on the surface of the conductive substrate, when the cross section consisting of the rolling direction and the plate thickness direction of the conductive substrate is viewed, the interface length per 20μm of the direction extending between the first base layer and the electrically conductive substrate, or the damaged layer by the length of 0.5~10μm is left, the interface length per 20μm A Sn plated material, wherein a plurality of work-affected layers are present in a total length of 0.5 to 10 μm.
(2) produced by rolling a metal material in one direction, on a conductive base material made of Cu or Cu alloy, a first base layer made of Ni or Ni alloy, a second base layer made of Cu or Cu alloy, An Sn plating material having respective layers in the order of an intermediate layer made of a CuSn compound and a surface layer made of Sn or an Sn alloy, and the Sn plating material was seen from a cross section formed of a rolling direction and a plate thickness direction of a conductive substrate . Sometimes, a work-affected layer remains on the surface of the conductive substrate at a length of 0.5 to 10 μm per 20 μm of interface length in the direction extending between the first underlayer and the conductive substrate. A Sn plated material, wherein a plurality of work-affected layers exist in a total length of 0.5 to 10 μm per 20 μm of the interface length.
(3) The Sn plating material according to (1) or (2), wherein the first underlayer includes 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 plated 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 thickness of the first underlayer is 0.1 to 2 μm.
(7) The Sn plating material according to any one of (2) to (6), wherein the thickness of the second underlayer is 0 to 0.1 μm.
(8) Any one of (1) to (7), wherein the intermediate layer is exposed on the material surface at an area ratio of 0.1 to 60% when heat-treated at 175 ° C. for 240 hours. Sn plating material as described in claim | item.
(9) A vehicle-mounted component using the Sn plating material according to any one of (1) to (8).
(10) An electrical / electronic component using the Sn plating material according to any one of (1) to (8).
(11) Manufactured by rolling a metal material in one direction, on a conductive base material made of Cu or Cu alloy, a first underlayer made of Ni or Ni alloy, an intermediate layer made of CuSn compound, Sn or Sn alloy A method for producing a Sn-plated material in which each layer is formed in the order of the surface layer comprising:
After forming the first underlayer, the second underlayer made of Cu or Cu alloy, and the surface layer in this order on the conductive base material, the second underlayer and the surface layer are formed by reflow treatment. React until the second underlayer disappears to form the intermediate layer,
The buffing and pickling conditions of the conductive base material are as follows: The size of the buffing 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 0 to 70%. And adjusting the residual amount of the work-affected layer on the surface of the conductive substrate by adjusting the finish heat treatment condition at 250 to 650 ° C. for 5 seconds to 5 hours depending on the case. The material has a direction extending between the first base layer and the conductive base material on the surface of the conductive base material when the cross section formed of the rolling direction and the plate thickness direction of the conductive base material is viewed . in the interface length per 20 [mu] m, or to leave the damaged layer at a length of 0.5 to 10 [mu] m, the surface length per 20 [mu] m, more process-damaged layer by the length of 0.5 to 10 [mu] m in total The manufacturing method of Sn plating material characterized by making it do.
(12) manufactured by rolling a metal material in one direction, a first base layer made of Ni or Ni alloy on a conductive base material made of Cu or Cu alloy, a second base layer made of Cu or Cu alloy, A method for producing a Sn plating material in which each layer is formed in the order of an intermediate layer made of a CuSn compound and a surface layer made of Sn or a Sn alloy,
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 reflowed to form the second base layer. React to form part of the intermediate layer,
The buffing and pickling conditions of the conductive base material are as follows: The size of the buffing 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 0 to 70%. And adjusting the residual amount of the work-affected layer on the surface of the conductive substrate by adjusting the finish heat treatment condition at 250 to 650 ° C. for 5 seconds to 5 hours depending on the case. The material has a direction extending between the first base layer and the conductive base material on the surface of the conductive base material when the cross section formed of the rolling direction and the plate thickness direction of the conductive base material is viewed . in the interface length per 20 [mu] m, or to leave the damaged layer at a length of 0.5 to 10 [mu] m, the surface length per 20 [mu] m, more process-damaged layer by the length of 0.5 to 10 [mu] m in total The manufacturing method of Sn plating material characterized by making it do.

According to the Sn-plated material of the present invention, a part of the work-affected layer remains on the surface of the conductive base material, thereby suppressing the diffusion of the base material component Cu from the conductive base material to the surface layer. Can be obtained. Moreover, the crack of the contact part formed by a bending process or an overhanging process 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.

It is sectional drawing of one Embodiment of Sn plating material of this invention. It is sectional drawing of another embodiment of Sn plating material of this invention. It is sectional drawing of the overhang | projection processing method performed in the Example. It is sectional drawing of the Sn plating material by which the overhanging process performed in the Example was carried out. It is a conceptual diagram which shows typically the state deteriorated over time.

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 is manufactured by rolling a metal material in one direction, and is formed on a conductive substrate (1) made of Cu or a Cu alloy. Each layer is formed in the order of a first underlayer (2) made of an alloy, an intermediate layer (4) made of a CuSn compound, and a surface layer (5) made of Sn or an Sn alloy. In some cases, as shown in FIG. 2, a second underlayer (3) made of Cu or Cu alloy may be formed between the first underlayer (2) and the intermediate layer (4). In either case, the work-affected layer (6) remains between the first underlayer (2) and the conductive substrate (1) with the predetermined length.

  By leaving a part of the work-affected layer on the surface of the conductive base material, a first ground layer having a small crystal grain size is formed on the conductive base material in that portion, and in the part where the work-affected layer has been removed. The first underlayer having a large crystal grain size is formed. A portion having a small crystal grain size contributes to improvement of workability, and a portion having a large crystal grain size suppresses diffusion of the base material component Cu from the conductive base material to the surface layer, thereby contributing to improvement in heat resistance. The surface layer disappears or decreases due to the diffusion of the base material component Cu from the conductive base material immediately above the portion where the crystal grain size of the first underlayer is small, but the surface layer remaining directly above the portion where the crystal grain size is large Therefore, good heat resistance can be obtained as a whole. In addition, when maintenance is performed after use in a high-temperature environment such as an in-vehicle terminal, the insertion force at the time of insertion / removal is reduced from the initial stage due to the effect of the intermediate layer grown immediately above the portion where the crystal grain size of the first underlayer is small .

There is no restriction | limiting in particular in the shape of an electroconductive base material (1), For example, there exist a board, a strip, foil, a line | wire, etc. Below, although a board | plate material and a strip are demonstrated as embodiment, the shape is not limited to these. Cu or Cu alloy is used for the conductive substrate (1). The kind of Cu or Cu alloy is not particularly limited, and may be appropriately selected according to the demands for strength, conductivity and the like of the intended use.
As an example of a copper alloy that can be used for the conductive substrate (1), CDA (Copper Development Association) listed alloy “C14410 (Cu-0.15Sn, Furukawa Electric 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, Furukawa Electric Co., Ltd. ), Trade name: EFTEC64T), “C64770 (Cu—Ni—Si based alloy material, Furukawa Electric Co., Ltd., trade name: EFTEC-97)”, “C64775 (Cu—Ni—Si based alloy material) , Furukawa Electric Co., Ltd., trade name: EFTEC-820) "and the like can be used. (The unit of the number before each element of the copper alloy indicates mass% in the copper alloy.) Also, TPC (tough pitch copper), OFC (oxygen-free copper), phosphor bronze, brass (for example, 70 mass) % Cu-30 mass% Zn, abbreviated as 7/3 brass), etc. can also be used. From the viewpoint of improving conductivity and heat dissipation, it is preferable to use a copper alloy strip having a conductivity of 5% IACS or more. In addition, when handling a copper alloy as an electroconductive base material (1), the "base material component" of this invention shall show the copper which is a base metal. Although there is no restriction | limiting in particular in the thickness of an electroconductive base material (1), Usually, it is 0.05-2.00 mm, Preferably, it is 0.1-1.2 mm.

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

  The first underlayer (2) formed by, for example, plating on the conductive substrate (1) is oriented to the conductive substrate (1) at the portion where the work-affected layer (6) is removed, and Ni crystal grains And a crystal grain size comparable to that of the conductive substrate (1) is obtained. Since the crystal grain size of Cu or Cu alloy is generally about 1 to 30 μm, the crystal grain size of the first underlayer (2) (Ni) formed on the portion from which the work-affected layer (6) has been removed is Most of them are 1 μm or more. On the other hand, in the portion where the work-affected layer (6) remains, the crystal grain size of the first underlayer (2) in the vicinity of the surface of the conductive base material (6) is much larger than the original crystal grain size of the base material. The first underlayer (2) (Ni) obtained thereon has a small crystal grain size of 0.01 μm or more and less than 1 μm.

The intermediate layer (4) is formed by sequentially forming the second underlayer (3) and the surface layer (5) on the first underlayer (2), and then performing a reflow process, whereby the second underlayer (3) and the surface layer are formed. (5) is obtained by the reaction, and is mainly composed of Cu ₃ Sn and Cu ₆ Sn ₅ . Consisting mainly of Cu ₃ Sn and Cu ₆ Sn ₅ means that Cu ₃ Sn and Cu ₆ Sn ₅ are composed of 50% by mass or more. The intermediate layer (4) acts as a diffusion barrier layer that prevents the reaction between the surface layer (5) and the first underlayer (2). The thickness of the intermediate layer (4) is preferably 0.1 to 1 μm, and more preferably 0.2 to 0.8 μm. If it is too thin, the effect as a diffusion barrier layer is reduced, the reaction between the surface layer (5) and the first underlayer (2) proceeds, and the heat resistance of the Sn plating material (10) decreases. Moreover, when too thick, workability will fall and there exists a possibility that a crack may arise.

  The surface layer (5) is necessary to ensure the electrical connectivity of the contacts. The thickness of the surface layer (5) is preferably 0.2 to 5 μm, and more preferably 0.3 to 2 μm. When too thin, Sn reacts with Cu diffused from the conductive base material (1) at a high temperature and disappears, and electrical connectivity is impaired. If it is too thick, the influence of the hard intermediate layer (4) near the surface is reduced, and the influence of the surface layer (5) made of soft Sn or Sn alloy is increased. The insertion / extraction force increases and the work load increases. In particular, the insertion force can be significantly reduced by setting the thickness to 2 μm or less. The surface layer (5) may be formed of an Sn alloy. For example, Sn—Cu, Sn—Bi, Sn—Pb, Sn—Ag, Sn—Sb, Sn—In, or the like can be used.

  A second underlayer (3) may be formed between the first underlayer (2) and the intermediate layer (4). When the second underlayer (3) is reflow-treated after forming the second underlayer (3), the intermediate layer (4), and the surface layer (5) in this order on the first underlayer (2), FIG. As shown, all of the second underlayer (3) may be used to form the intermediate layer (4) and disappear, or, as shown in FIG. 2, the second underlayer (3) A part of the second underlayer (3) that is not used for forming the intermediate layer (4) may remain without being used. The thickness of the remaining second underlayer (3) is preferably 0 to 0.1 μm, and more preferably 0 to 0.05 μm. Similar to the intermediate layer (4), the second underlayer (3) acts as a diffusion barrier layer that prevents the reaction between the surface layer (5) and the first underlayer (2). However, if it is too thick, it reacts with the surface layer (5) on the surface at a high temperature, which causes a decrease in heat resistance. Examples of the Cu alloy used as the second underlayer (3) include Cu—Ni and Cu—Sn.

In the present embodiment, a part of the work-affected layer (6) remains on the surface of the conductive substrate (1) produced by rolling a metal material in one direction . The work-affected layer (6) itself is conventionally known. Explaining the work-affected layer (6), it is a layer formed under the influence of the heat and working force generated in the buffing process and rolling process (machining), the ambient atmosphere, the properties of the new metal surface, etc. It exhibits a finer structure than the crystal structure inside the metal substrate. In the work-affected layer (6), fine crystals and non-crystal parts are mixed, and the size of crystal grains existing in the work-affected layer (6) is 1 μm or less. The work-affected layer is composed of a Bailby layer (upper layer) and a plastically deformed layer (lower layer). Here, the Bailby layer is made of an extremely fine crystal texture or amorphous structure. On the other hand, the plastically deformed layer has a strained and non-uniform crystal texture, and the size of the crystal grains is approximately the middle size between the crystal grains of the Bailby layer and the crystal grains inside the metal substrate.
Since the work-affected layer is a thermally unstable structure, it changes into a thermally stable atomic arrangement by atomic diffusion due to heat during heat treatment, and decreases. By dissolving the surface of the conductive substrate, part or all of the work-affected layer can be removed. The Sn plating material (10) of the present embodiment has a first underlayer (2) on the surface of the conductive base material (1) when a cross section formed of the rolling direction and the plate thickness direction of the conductive base material is viewed. and the interface length per 20μm of the direction extending between the electrically conductive substrate (1), or the damaged layer in the length of 0.5 to 10 [mu] m (6) are still present, or, the interface length Preferably, a plurality of work-affected layers (6) are present in a total length of 0.5 to 10 μm per 20 μm, and one or more work-affected layers (6) are 1 to 5 μm in total. More preferably, it remains. If the length of the work-affected layer (6) is too short, the crystal grain size of most of the first underlayer (2) (Ni) is large, and cracks occur at the contact portion due to a decrease in workability, resulting in electrical connectivity. May be damaged. On the contrary, when the length of the work-affected layer (6) is too long, the crystal grain size of most of the first underlayer (2) (Ni) is small, and the surface layer (5) from the conductive substrate (1) There is a risk that the base material component Cu diffuses into the substrate and the heat resistance decreases.

  In the present embodiment, since the Ni crystal grain size of the first underlayer (2) is small immediately above the portion where the work-affected layer (6) remains, the surface layer (5) is formed from the conductive substrate (1). Diffusion of the base material component Cu proceeds to the intermediate layer (4), which is easy to grow. On the other hand, in the part where the work-affected layer (6) is removed, the Ni crystal grain size of the first underlayer (2) is large, and the base material from the conductive base material (1) to the surface layer (5) The diffusion of the component Cu is suppressed and the intermediate layer (4) is difficult to grow. Therefore, when this embodiment is used at a high temperature, a difference occurs 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) (FIG. 5). checking.). When the intermediate layer (4) is partially exposed after use under high temperature, for example, when performing insertion / extraction for maintenance of the vehicle-mounted terminal, the insertion force is reduced from the initial stage, and the work load is reduced. When the intermediate layer (4) is exposed to 0.1 to 60% on the surface of the Sn plating material (10) after being heated at 175 ° C. for 240 hours, an insertion force lower than the initial value and good electrical connectivity can be obtained at the same time. . In order to obtain an insertion force lower than the initial level and good electrical connectivity at the same time, the area ratio of the exposed intermediate layer (4) is preferably 0.1 to 60%, and preferably 0.5 to 40%. Is more preferable, and it is further more preferable that it is 1 to 30%. When the area ratio of the exposure of the intermediate layer (4) is too small, a low insertion force cannot be obtained, and when it is too large, good electrical connectivity cannot be obtained.

  Next, the manufacturing method of Sn plating material (10) of this embodiment is demonstrated. The Sn-plated material (10) of this embodiment is typically obtained by sequentially performing Ni or Ni alloy plating → Cu or Cu alloy plating → Sn or Sn alloy plating on the conductive substrate (1) made of Cu or Cu alloy, and thereafter Manufactured by performing a reflow process. Before and after each step, degreasing, pickling, washing with water, and drying treatment may be appropriately performed. In the manufacturing method of this embodiment, it is important to leave a part of the work-affected layer (6) on the surface of the conductive substrate (1) before Ni or Ni alloy plating. In the manufacturing method of the present embodiment, the remaining amount of the work-affected layer (6) is controlled by adjusting the buffing of the conductive base material, adjusting the pickling conditions, and adjusting the processing rate of the finishing processing conditions to 0 to 70%. To do. Moreover, you may implement finishing heat processing conditions in 250-650 degreeC for 5 second-5 hours as needed. Although the manufacturing method of this embodiment has the same number of steps as the conventional method, the material characteristics are improved by appropriately adjusting each process condition.

<Conductive substrate>
The conductive substrate (1) is not particularly limited as long as it is Cu or a Cu alloy, and may be appropriately selected in accordance with requirements such as strength and conductivity for the application to be used. Process-affected layer (6) on the surface of the conductive substrate (1) is required for buffing after heat treatment and buffing in the pickling process, surface dissolution in pickling solution, or finishing processing rate, and further required It can be controlled by adjusting the finish annealing conditions accordingly. The buff polishing amount and the surface dissolution amount in the pickling solution can be controlled by the size of the buffing particles, the pickling solution composition, the dipping time in the pickling solution, and the like. Specifically, the size of the buffing particles is controlled from # 1000 to 5000, and the immersion time in the pickling solution is controlled from 0 to 60 seconds. If the size of the buffing particles 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. It becomes difficult to obtain the effect. If the immersion time in the pickling solution is longer than 60 seconds, the surface of the conductive substrate (1) may be acid burned and a normal plating film may not be obtained. An immersion time of 0 seconds means no pickling. As the pickling solution, a sulfuric acid aqueous solution, a hydrofluoric acid aqueous solution, a nitric acid aqueous solution, a phosphoric acid aqueous solution, or the like can be used. The finishing process can be performed at a processing rate of 0 to 70%, for example. Here, the finishing process of 0% means that the finishing process is not performed. When the finishing rate exceeds 70%, the bending workability of the obtained Sn plating material (10) is significantly lowered. Moreover, when implementing final annealing, it can implement for 5 seconds-5 hours, for example at 250-650 degreeC. If the temperature is lower or shorter than this condition, it is difficult to obtain the effect of finish annealing, and the remaining amount of the work-affected layer may be larger than the specified range. Further, when the temperature is high or the time is long, the remaining amount of the work-affected layer is less than the specified range, and the material strength of the Sn plating material (10) may be significantly reduced.

<Ni or Ni alloy plating for forming the first underlayer (2)>
Ni or Ni alloy may be plated by a general method. As the plating bath, for example, a sulfamine bath, a watt bath, a sulfuric acid bath, or the like can be used. 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 for forming the second underlayer (3)>
Cu or Cu alloy may be plated by a general method. For example, a sulfuric acid bath or a cyan bath can be used as the plating bath. 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 for forming the surface layer (5)>
The Sn or Sn alloy may be plated by a general method. As the plating bath, for example, a sulfuric acid bath can be used. 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 the surface layer (5) can be performed by a general method. For example, the material may be passed through a furnace set to 400 to 800 ° C., heated for 5 to 20 seconds, and then cooled. By the reflow process, the second underlayer (3) and the surface layer (5) react to form the intermediate layer (4).
Therefore, when the intermediate layer (4) is formed by reacting the second underlayer (3) and the surface layer (5) until the second underlayer (3) disappears by reflow treatment, the first layer as shown in FIG. There is no second underlayer between one underlayer (2) and the intermediate layer (4).
In addition, when the intermediate layer (4) is formed by reacting the second underlayer (3) and the surface layer (5) so that a part of the second underlayer (3) remains by reflow treatment, as shown in FIG. A second underlayer (3) is formed between the first underlayer (2) and the intermediate layer (4).

  The Sn-plated material (10) of the present embodiment allows a part of the work-affected layer (6) to remain on the surface of the conductive substrate (1), so that the conductive substrate (1) is transferred to the surface layer (5). The diffusion of the base material component Cu can be suppressed and good heat resistance can be obtained. Moreover, the crack of the contact part formed by a bending process or an overhanging process can be suppressed.

(Use of Sn plating material (10))
The Sn plating material (10) of this embodiment is excellent in heat resistance (electrical connectivity) particularly at high temperatures. For this reason, Sn plating material (10) of this embodiment is suitable for electric and electronic parts, such as terminals, connectors, and lead frames, in addition to in-vehicle parts such as small terminals and high-voltage, high-current terminals.

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

After buffing and pickling, finishing and finishing annealing on a copper alloy substrate (Furukawa Electric Co., Ltd., trade name: EFTEC-97) with a plate thickness of 0.25 mm, electrolytic degreasing and pickling are performed. Ni plating, Cu plating, and Sn plating were applied in this order, and a 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. In addition, buffing, pickling, finishing, and finish annealing were controlled so that the remaining amount of the work-affected layer in the cross section of the substrate after the reflow treatment was within a specified range. The buffing amount was adjusted by adjusting the size of the buffing particles to a range of # 1000 to 5000. The surface dissolution amount was adjusted by adjusting the immersion time in the mixed aqueous solution of sulfuric acid and hydrogen peroxide as the pickling solution in the range of 0 to 60 seconds. The finishing rate was adjusted in the range of 0 to 70%, and the final annealing was adjusted at 250 to 650 ° C. for 5 seconds to 5 hours. The remaining amount of the work-affected layer was measured by the method described later.
Under such conditions, as shown in Table 2 described later, Sn plated materials (10) of Invention Examples 1 to 7 having different layer thickness configurations were produced as examples falling within the scope of the present invention.
In addition, as a comparative example, an Sn plated material in which the remaining amount of the work-affected layer is outside the definition of the present invention was also produced (Comparative Examples 1, 2, 3, 4).
Here, Comparative Example 1 corresponds to the case where there is no work-affected layer of Patent Document 3 (Examples 1 to 6 of Patent Document 3), and is immersed in the pickling solution for 60 seconds after buffing in the buffing and pickling steps. However, it was produced by not performing finishing and finishing annealing. Comparative Example 4 corresponds to the case where the work-affected layer remains on the entire surface of the conductive substrate (1) (Comparative Example 1 of Patent Document 3), and 70% finishing is performed after buffing and pickling. It was produced by not performing finish annealing. Comparative Examples 2 and 3 are examples in which part of the work-affected layer remains on the conductive substrate and the remaining amount is adjusted so as not to fall within the specified range of the present invention. In Comparative Example 2, finishing is performed after buffing and pickling, and finish annealing is performed at 675 ° C. for 2 hours, which is higher than the temperature specified in the present invention. Less. In Comparative Example 3, finishing is performed after buffing and pickling, and finish annealing is performed at 225 ° C. for 2 hours, which is lower than the temperature specified in the present invention. There are many.

[Cathode electrolytic degreasing]
Degreasing solution: NaOH 60 g / liter Degreasing conditions: 2.5 A / dm ² , temperature 60 ° C., degreasing time 60 seconds

[Pickling]
Pickling solution: 10% sulfuric acid pickling condition: 30 seconds immersion, room temperature

  The following evaluation was performed on the specimens thus produced.

(Measurement of Sn plating thickness)
The layer thickness of each layer of the Sn plating material produced above was measured by the constant current dissolution method described in JIS H 8501 No. 10.

(Structure observation-Remaining amount of work-affected layer)
By observing the cross section of the Sn plating material (10) produced above by the FIB-SIM (focused ion beam-scanning ion microscope) consisting of the rolling direction and the plate thickness direction of the conductive substrate, the conductive substrate ( The length (residual amount) of the work-affected layer (6) remaining on the surface of 1) was measured. Observation was performed at a magnification of 10,000 to 50,000 times. The measurement includes a range including an interface length of 20 μm in the direction extending between the first underlayer and the conductive substrate , about the interface between the first underlayer (2) and the conductive substrate (1). and a field, after the interface length remaining to have part of the work-affected layer on 3-field as the visual field range do not overlap (6) were measured, and the average value was used as the measurement result. Alternatively, it was confirmed that a plurality of work-affected layers (6) exist with a total length of 0.5 to 10 μm per 20 μm of the interface length. The interface position between the first underlayer (2) and the conductive substrate (1) was determined by using elemental mapping using Auger electron spectroscopy attached to the FIB. In addition, the work-affected layer (6) is removed from the portion where the first base layer (2) immediately above is oriented to the conductive substrate (1) and the Ni crystal grain boundary coincides with the Cu crystal grain boundary. Judged that it has been. On the other hand, it was judged that the work-affected layer (6) remained in a portion where the Ni crystal grain size of the first underlayer (2) was smaller than the Cu crystal grain boundary of the conductive substrate (1).

(Heat resistance at high temperature)
Constant current test method described in 10 of JIS H 8501 for Sn remaining amount after heating at 160 ° C. for 1000 hours (160 ° C. heat resistance) and Sn remaining amount after heating at 175 ° C. for 240 hours (175 ° C. heat resistance) A (good) was evaluated when Sn was remained even a little, and D (poor) was evaluated as not remaining at all.
FIG. 5 schematically shows a state of deterioration over time due to the high temperature (for example, a state of being left at 150 ° C. for 1000 hours). In FIG. 5, the intermediate layer (4) and the surface layer (5) on the intermediate layer (4) remain in the portion where the work-affected layer (6) does not exist, but the intermediate layer (4) immediately above the work-affected layer (6). The surface layer (5) is almost lost due to thickening.

(Overhang processability)
The Sn-plated material (10) produced above was stretched, and A (good) was obtained when no plating cracking occurred after processing, and D (poor) was produced. Judgment of the plating crack was made by observing the surface of the projecting portion after processing with an optical microscope at 50 to 500 times, and judging that a crack occurred on the exposed base material. FIG. 3 is a schematic cross-sectional view of the overhang processing method and the overplated Sn plating material (10). In the overhanging process, the fixed Sn plating material (10) produced as described above was deformed by pressing a jig with a 0.5 mmR hemisphere at the tip and processed. In the figure, O represents the center of the hemisphere at the tip of the jig used for the overhanging process. FIG. 4 is a schematic cross-sectional view of the Sn plating material (10) after the overhang processing. In the figure, O represents the center of the hemisphere of the overhanging portion.

(Exposed area ratio of intermediate layer (CuSn compound layer) on Sn plating material surface after high-temperature heating)
The surface of the Sn-plated material (10) prepared above after heating at 175 ° C. for 240 hours 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 element mapping attached to the SEM in combination. A (excellent) with an exposed area ratio of 1 to 30%, B (good) with 0.5% to less than 1%, or greater than 30% and 40% or less, 0.1% to 0.5% Less than or greater than 40% and less than or equal to 60% was defined as C (possible), and less than 0.1% or greater than 60% was defined as D (poor).

Table 2 summarizes the plating thickness (layer thickness) of each layer of the Sn plating material (10) produced above, the remaining amount (length) of the work-affected layer, and the characteristics.
Here, in Table 2, the column “Ni” in the column “Layer thickness (μm)” indicates the thickness of the first underlayer (2), and the column “Cu” is the second lower The thickness of the formation (3) is shown, the column described as “CuSn” indicates the thickness of the intermediate layer (4), and the column described as “Sn” indicates the thickness of the surface layer (5). In these invention examples, when the “Cu” layer, that is, the second underlayer (3) is 0 μm, it is the embodiment shown in FIG. 1, and the “Cu” layer, that is, the second underlayer (3) is not 0 μm. The case is the embodiment shown in FIG.
In Table 2, Invention Examples 1 to 7 that satisfy the conditions of the present invention were all excellent in heat resistance and overhang workability.
On the other hand, Comparative Examples 1 to 4 resulted in inferior evaluation of either heat resistance or overhang processability. In Comparative Examples 1 and 2 in which the remaining amount of the work-affected layer is less than the specified range of the present invention, the overhang processability is inferior. In Comparative Example 1, the exposed area of the intermediate layer (4) after heating at 175 ° C. for 240 hours. The rate was very small. Further, in Comparative Examples 3 and 4 in which the remaining amount of the work-affected layer is larger than the specified range of the present invention, the heat resistance when heated at 175 ° C. for 240 hours is inferior, and the exposed area ratio of the intermediate layer (4) is very high after heating The surface layer (5) hardly remained.
From the above, it was confirmed that the Sn plating material that satisfies the conditions of the present invention exhibits excellent characteristics.

  While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

  This application claims the priority based on Japanese Patent Application No. 2015-172147 for which it applied for a patent in Japan on September 1, 2015, and this is referred to here for the contents of this specification. Capture as part.

DESCRIPTION OF SYMBOLS 1 Conductive base material 2 1st foundation layer 3 2nd foundation layer 4 Intermediate layer 5 Surface layer 6 Work-affected layer 10 Sn plating material

Claims (12)

It is manufactured by rolling a metal material in one direction, on a conductive substrate made of Cu or Cu alloy, a first underlayer made of Ni or Ni alloy, an intermediate layer made of CuSn compound, a surface made of Sn or Sn alloy An Sn plating material having respective layers in the order of the layers, and the Sn plating material is formed on the surface of the conductive substrate on the surface of the conductive substrate when viewed from the rolling direction and the plate thickness direction. A work-affected layer remains at a length of 0.5 to 10 μm per 20 μm of interface length in a direction extending between the base layer and the conductive base material , or a plurality of degenerated layers per 20 μm of the interface length. A Sn-plated material, wherein the work-affected layers are present in a total length of 0.5 to 10 μm. Made by rolling a metal material in one direction, on a conductive base material made of Cu or Cu alloy, a first base layer made of Ni or Ni alloy, a second base layer made of Cu or Cu alloy, a CuSn compound An Sn plating material having each layer in the order of an intermediate layer, a surface layer made of Sn or an Sn alloy, and when the Sn plating material is viewed from a cross section consisting of a rolling direction and a plate thickness direction of the conductive substrate , Whether the work-affected layer remains on the surface of the conductive substrate at a length of 0.5 to 10 μm per 20 μm of interface length in the direction extending between the first base layer and the conductive substrate. A Sn-plated material, wherein a plurality of work-affected layers are present in a total length of 0.5 to 10 μm per 20 μm of the interface length.   3. The Sn plated material according to claim 1, wherein the first underlayer includes 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.   The Sn plating material according to claim 1, wherein a thickness of the surface layer is 0.2 to 5 μm.   The Sn plating material according to claim 1, wherein the intermediate layer has a thickness of 0.1 to 1 μm.   The Sn plating material according to claim 1, wherein a thickness of the first underlayer is 0.1 to 2 μm.   The Sn plating material according to any one of claims 2 to 6, wherein the second underlayer has a thickness of 0 to 0.1 µm.   The Sn according to any one of claims 1 to 7, wherein the intermediate layer is exposed on the material surface at an area ratio of 0.1 to 60% when heat-treated at 175 ° C for 240 hours. Plating material.   The vehicle-mounted component using the Sn plating material of any one of Claims 1-8.   The electrical / electronic component using the Sn plating material of any one of Claims 1-8. It is manufactured by rolling a metal material in one direction, on a conductive substrate made of Cu or Cu alloy, a first underlayer made of Ni or Ni alloy, an intermediate layer made of CuSn compound, a surface made of Sn or Sn alloy It is a manufacturing method of Sn plating material in which each layer was formed in order of layers,
After forming the first underlayer, the second underlayer made of Cu or Cu alloy, and the surface layer in this order on the conductive base material, the second underlayer and the surface layer are formed by reflow treatment. React until the second underlayer disappears to form the intermediate layer,
The buffing and pickling conditions of the conductive base material are as follows: The size of the buffing 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 0 to 70%. And adjusting the residual amount of the work-affected layer on the surface of the conductive substrate by adjusting the finish heat treatment condition at 250 to 650 ° C. for 5 seconds to 5 hours depending on the case. The material has a direction extending between the first base layer and the conductive base material on the surface of the conductive base material when the cross section formed of the rolling direction and the plate thickness direction of the conductive base material is viewed . in the interface length per 20 [mu] m, or to leave the damaged layer at a length of 0.5 to 10 [mu] m, the surface length per 20 [mu] m, more process-damaged layer by the length of 0.5 to 10 [mu] m in total The manufacturing method of Sn plating material characterized by making it do. Made by rolling a metal material in one direction, on a conductive base material made of Cu or Cu alloy, a first base layer made of Ni or Ni alloy, a second base layer made of Cu or Cu alloy, a CuSn compound A method for producing a Sn plating material in which each layer is formed in the order of an intermediate layer, a surface layer made of Sn or an Sn alloy,
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 reflowed to form the second base layer. React to form part of the intermediate layer,
The buffing and pickling conditions of the conductive base material are as follows: The size of the buffing 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 0 to 70%. And adjusting the residual amount of the work-affected layer on the surface of the conductive substrate by adjusting the finish heat treatment condition at 250 to 650 ° C. for 5 seconds to 5 hours depending on the case. The material has a direction extending between the first base layer and the conductive base material on the surface of the conductive base material when the cross section formed of the rolling direction and the plate thickness direction of the conductive base material is viewed . in the interface length per 20 [mu] m, or to leave the damaged layer at a length of 0.5 to 10 [mu] m, the surface length per 20 [mu] m, more process-damaged layer by the length of 0.5 to 10 [mu] m in total The manufacturing method of Sn plating material characterized by making it do.

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