JP7470575B2 - Electrical and electronic equipment parts - Google Patents

Description

The present invention relates to parts for electrical and electronic equipment.

In recent years, there has been a trend for electrical and electronic devices to generate more heat due to their improved functionality and performance. In addition, as electrical and electronic devices become smaller, the density of heat generated increases, making it important to cool the generated heat. One example of a component for cooling the generated heat is a vapor chamber, which is a planar heat pipe. It is desirable to use a copper-based material (pure copper, copper alloy) with high thermal conductivity as the material for the vapor chamber.

Here, the vapor chamber has an airtight structure formed by bonding the outer peripheries of a number of overlapping plates to form an internal space into which the working fluid is poured, and then the plates are bonded by reducing the pressure and sealing them in. Examples of such bonding methods include laser welding, resistance welding, diffusion bonding, and TIG welding.
When joining by welding, the weld is formed by heating to a high temperature to melt it once and then resolidifying it, which causes the problem that the weld becomes softer and weaker than the strength of the plate material itself, just like when the plate material is annealed. When the strength is lowered, the plate material becomes more susceptible to deformation.

To address these problems, Patent Document 1 discloses a method for manufacturing a vapor chamber by joining multiple parts by diffusion bonding or brazing, in which a precipitation hardening copper alloy is used as the material for the housing, and the housing is aged to cause precipitation hardening, thereby improving the strength of the housing.
However, the technique of Patent Document 1 has a problem that it is necessary to use a precipitation hardening copper alloy and cannot be applied to non-precipitation copper alloys or pure copper. In addition, the technique of Patent Document 1 has a problem that it requires aging treatment, which increases the number of steps and reduces productivity.
For this reason, it is desirable to increase the strength of welds by a method other than the method of precipitation hardening using a precipitation hardening copper alloy and aging treatment.

The problem of reduced strength of the welds mentioned above is not limited to vapor chambers, but also exists in other electrical and electronic devices such as bus bars.

Patent Document 2 discloses a technology for improving the joining strength by irradiating a laser along a specific trajectory, but the technology in Patent Document 2 is related to joining aluminum and copper, and is difficult to apply to joining copper-based materials together. In more detail, copper-based materials are difficult to join by laser welding because they have high thermal conductivity, which makes it easy for heat to escape, and because laser light is easily reflected. For this reason, simple welding using laser light, as in Patent Document 2, does not provide sufficient joining strength and is not possible.

International Publication No. 2017/164013 JP 2017-168340 A

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide a component for electrical and electronic equipment in which multiple plates made of copper-based material are joined by welding, and in which the welds have high strength.

As a result of extensive research, the inventors discovered that it is possible to increase the Vickers hardness HV of the welded portion by using a sheet material with a composition containing 90% by mass or more of Cu and controlling the laser welding conditions, and thus completed the present invention.

That is, the gist and configuration of the present invention are as follows.
(1) A component for electrical/electronic equipment, which is composed of a plurality of plate materials containing 90% or more by mass of Cu, and has a welded portion where the plurality of plate materials are butted against or overlapped with each other and joined together in a linear or point-like manner by welding, the welded portion extends across the entire thickness of the plate materials, and in a cross section obtained by cutting the welded portion in the direction in which the joined plate materials extend, the Vickers hardness of the welded portion is 60 or more when measured at a position equivalent to half the dimension of the thickness of the plate materials.
(2) The electrical/electronic device part according to (1) above, wherein when a GAM value obtained from crystal orientation analysis data by a SEM-EBSD method is measured in a rectangular region in the cross section defined by the weld width of the weld and the thickness of the plate material, crystal grains having a GAM value of 0.5° or more and less than 2.0° account for an area ratio of 25% or more to all crystal grains present in the measured area.
(3) The part for electric/electronic equipment according to (1) or (2) above, wherein the plate material contains one or more elements selected from the group consisting of Ag, Fe, Ni, Co, Si, Cr, Sn, Zn, Mg and P.
(4) The part for electric/electronic equipment according to (1) or (2) above, wherein the plate material contains 99.96 mass % or more of Cu and unavoidable impurities.
(5) The part for electric/electronic devices according to any one of (1) to (4) above, wherein the part for electric/electronic devices is a vapor chamber.
(6) The part for electric/electronic devices according to any one of (1) to (4) above, wherein the part for electric/electronic devices is a bus bar.

According to the present invention, it is possible to provide an electrical/electronic device component in which multiple plate members made of a copper-based material containing 90% or more by mass of Cu are joined by welding, and the welded joint has high strength.

FIG. 1A is a schematic perspective view of two Cu plate materials butted together and laser-welded in a line, and FIG. 1B is a schematic perspective view of two Cu plate materials overlapping each other and laser-welded in a line. This is an optical microscope photograph of the surface condition of the laser irradiated side of a Cu joint (a joint of two Cu plates) formed by laser welding two butted Cu plates together, observed from the Z-axis. 1 is an optical microscope photograph of the surface condition of a Cu joint formed by laser welding two butted Cu plates, the surface condition being observed on the side opposite to the side irradiated with the laser. 1 is an optical microscope photograph of a cross-sectional state of a Cu joint body in which Cu plates are laser-welded, observed from the X-axis. FIG. 1A is a schematic perspective view of two Cu plate materials butted together and laser-welded in spots, and FIG. 1B is a schematic perspective view of two Cu plate materials overlapping each other and laser-welded in spots, both of which show a cross section of the weld when cut in the direction in which the Cu joint extends. FIG. 1 is a diagram showing a schematic configuration of a laser welding device. FIG. 4 is a diagram showing a spot diameter of a laser beam from a laser welding device.

The following describes an embodiment of the present invention. The following description is an example of an embodiment of the present invention and does not limit the scope of the claims.

The electric/electronic device part according to the embodiment of the present invention is composed of multiple plate materials containing 90% or more by mass of Cu, and has a welded portion where the multiple plate materials are joined together in a line or point shape by welding while being butted against each other or overlapped, and the welded portion extends over the entire thickness of the plate materials, and the welded portion has a Vickers hardness of 60 or more when measured at a position equivalent to half the dimension of the thickness of the plate materials on a cross section obtained by cutting the welded portion in the direction in which the joined multiple plate materials extend.

1(a) is a schematic perspective view of a Cu joint 10 (joint of two Cu plates) formed by linearly laser welding two Cu plates 1 and 2 in a butted state, and FIG. 1(b) is a schematic perspective view of a Cu joint 10A formed by linearly laser welding two Cu plates 1 and 2 in a superposed state. In the embodiment shown in FIG. 1(a), the Cu plates 1 and 2 have a welded portion 3 that is linearly joined and integrated when butted together, and this portion is joined by laser welding. In the embodiment shown in FIG. 1(b), the Cu plates 1 and 2 have a welded portion 3A that is integrated when overlapped, and this portion is joined by laser welding. The welded portion 3 extends over the entire thickness of the plates 1 and 2. That is, in FIG. 1(a) and FIG. 1(b), the welded portion 3 melts and solidifies so as to melt from the surface on the side irradiated with the laser to the surface (rear surface) on the opposite side, and exists so as to penetrate the plates 1 and 2 in the thickness direction. In this context, "Cu sheet material" refers to sheet material that contains 90% or more by mass of Cu (copper).

Here, the "plate material containing 90% by mass or more of Cu" is not particularly limited as long as it is a plate material with a Cu content of 90% by mass or more, and may be pure Cu or any Cu alloy.
When the plate material is a Cu alloy, the plate material preferably has a composition containing one or more elements selected from Ag, Fe, Ni, Co, Si, Cr, Sn, Zn, Mg, and P as alloy components, with the balance being Cu of 90 mass% or more. The Cu alloy may be a precipitation hardening type Cu alloy or a non-precipitation hardening type Cu alloy. When the plate material is a Cu alloy, the Vickers hardness HV of the plate material varies depending on the type and amount of the alloy components added, so is not particularly limited, but is generally 75 to 240, for example.
In addition, when the plate material is pure Cu, the plate material has a Cu content of 99.96 mass% or more, and the total of inevitable impurities Cd, Mg, Pb, Sn, Cr, Bi, Se and Te is 5 ppm or less, and the total of Ag and O is 400 ppm or less. Pure Cu has excellent thermal conductivity and can exhibit excellent performance as a heat dissipation and cooling member. Examples of so-called pure Cu include electrolytic copper, oxygen-free copper (OFC), and TPC. When the plate material is pure Cu, the Vickers hardness of the plate material is not particularly limited, but is generally 65 to 120, for example.

In the present invention, the term "plate material" refers to a material that has been processed into a specific shape, such as a plate, strip, foil, rod, rectangular wire, etc., and has a specific thickness, and in a broad sense includes strip material. In the present invention, the thickness of the plate material (plate thickness) is not particularly limited, but is preferably 0.05 to 1.0 mm, and more preferably 0.1 to 0.8 mm. The shapes and thicknesses of the multiple plate materials to be joined may be the same or different.

2 is a photograph showing the surface state of the laser-irradiated side of a Cu joint 10 formed by laser welding two butted Cu plates 1 and 2. The X-axis direction is the laser sweep direction, i.e., the welding direction. It can also be seen that there are parts where the rolling processing marks of the Cu plates have disappeared due to the irradiation of the laser light. Furthermore, there are parts where the Cu plates 1 and 2 have melted and solidified again, which are called welded parts 3.
FIG. 3 is an optical microscope photograph of the surface condition of a Cu joint 10 formed by laser welding two butted Cu plate materials 1 and 2, the surface condition being observed on the side opposite to the side irradiated with the laser, and is an optical microscope photograph of the surface condition of the back side of FIG. 2.
As shown in Figures 2 and 3, the welded portion 3 extends over the entire thickness of the plate materials 1 and 2, so that the laser welding marks appear on the surface (front) of the Cu joint body 10 on the side irradiated with the laser and on the surface (back) opposite to the side irradiated with the laser. As shown in Figures 2 and 3, the width of the laser welding marks on the surface irradiated with the laser is wider than that on the surface opposite to the side irradiated with the laser. The width of the laser welding marks on the surface irradiated with the laser is defined as the weld width in the present invention, and the plate was cut at the cross-sectional observation position indicated by the dotted line, and the cross-sectional structure was observed.
Fig. 4 is an optical microscope photograph showing a cross-sectional state when a Cu joint is formed by laser welding Cu plates. As shown in Fig. 4, the width of the surface of the welded part on the side irradiated with the laser, which is melted by laser irradiation and solidified again, corresponds to the weld width. The weld width can also be seen from the cross-sectional view shown in Fig. 4.

In the present invention, the Vickers hardness of the weld is 60 or more when measured at a position equivalent to half the thickness of the plate material on a cross section of the welded portion cut in the direction in which the two joined plate materials extend. Note that in this specification, the Vickers hardness HV is measured in accordance with the method specified in JIS Z2244 (2009).

In more detail, in the case of a welded portion 3 in which two Cu plates 1 and 2 are joined together in a line while butting against each other as shown in FIG. 1(a), the welding direction (laser sweep direction) is the X-axis direction, the direction perpendicular to the welding direction (width direction of the plate material) is the Y-axis direction, and the normal direction of the plate material (thickness direction of the plate material) is the Z-axis direction. The direction L in which the two joined plate materials 1 and 2 extend is the direction in which the plate materials are brought closer together to be butted against each other, that is, the Y-axis direction. In the case of the electric/electronic device part of this embodiment having such a joint 10 configuration, the welded portion 3 present on the cross section A when the Cu joint 10 is cut in the Y-axis direction must have a Vickers hardness of 60 or more at a position b corresponding to half the dimension of the thickness a of the Cu plates 1 and 2.

1(b), in the case of a welded portion 3A in which two Cu plates 1 and 2 are linearly joined together while overlapping each other, the direction in which the two joined plates 1 and 2 extend is perpendicular to the welding direction, i.e., the Y-axis direction. In the case of the electric/electronic device part of this embodiment having such a configuration of the joint 10A, when the Cu joint 10A is cut in the Y-axis direction, it is necessary that the Vickers hardness is 60 or more at _both a position _b1 corresponding to _half the dimension of the thickness _a1 of the Cu plate 1 at the welded portion present on the cross section A1 of the Cu plate 1 and a position _b2 corresponding to half the dimension of the thickness _a2 of the Cu plate 2 at the welded portion present on the cross section A2 of the Cu plate 2.

When joining by welding, the weld is formed by heating to a high temperature to melt it once and then resolidifying it, so in conventional joining methods, there is a problem that the plate becomes softer and has lower strength than the plate itself, just like when the plate is annealed. When the strength is lowered, the plate becomes more susceptible to deformation.
However, as shown in the examples described later, by using a plate material having a composition containing 90 mass % or more of Cu and controlling the laser welding conditions, it is possible to suppress the decrease in strength due to softening of the welded portion. Depending on the laser welding conditions, the strength can be made higher than that of the plate material itself.
Therefore, in this embodiment, the Vickers hardness of the welded portion can be 60 or more, and even 65 or more. Since the Vickers hardness of the welded portion is high at 60 or more, it is possible to provide an electric/electronic device part having high strength and excellent deformation resistance. Since the Vickers hardness and the strength are proportional to each other, the strength increases when the Vickers hardness is high. Note that, when performing aging treatment as in Patent Document 1, unless a hardening type copper alloy is used, the entire Cu joint including the welded portion tends to be heated and softened, so it is considered difficult to maintain the Vickers hardness of the welded portion at 60 or more.

The upper limit of the Vickers hardness HV of the weld is not particularly limited, but in the case of pure Cu, it is, for example, 90 or less, and in the case of Cu alloy, it is, for example, 130 or less.

The above describes linear laser welding, but FIGS. 5(a) and (b) show point-wise laser welding. FIG. 5(a) is a schematic perspective view of two Cu plate materials 1 and 2 butted together and laser-welded in points to form a Cu joint 10B, and FIG. 5(b) is a schematic perspective view of two Cu plate materials 1 and 2 overlapping each other and laser-welded in points to form a Cu joint 10C.

As shown in FIG. 5(a), in the case of the electric/electronic device component of this embodiment having a Cu joint 10B having a welded portion 3B that is joined and integrated in a point-like manner while butting against each other, the Vickers hardness must be 60 or more at a position b that passes through the center c of the welded portion 3B on the plate surface and corresponds to half the dimension of the thickness a of the Cu plate materials 1 and 2 of the welded portion 3B that exists on a cross section A when the joint 10B is cut in the extension direction L of the Cu plate materials 1 and 2.

In addition, in the case of the electrical/electronic device part of this embodiment having a configuration of a Cu joint 10C having welded portions 3B that are joined together in a point-like manner while overlapping each other, as shown in Figure 5 (b), when the welded portion is cut in the stacking direction of the plate material through the center c of the welded portion on the plate material surface, the Vickers hardness must be ₆₀ or more at both position _b1 corresponding to half the dimension of the thickness a1 of the Cu plate material 1 of the welded portion present on cross section _A1 of the Cu plate material ₁ , and position b2 corresponding to half the dimension of the thickness _a2 of the Cu plate material ₂ of the welded portion present on cross section A2 of the Cu plate material 2.

In this specification, the Vickers hardness HV in the case of linear laser welding is measured at five cross sections A (YZ planes) cut at intervals of 1 mm in the welding direction (X-axis direction), and is calculated as the average of these measurement results.

In the present invention, when the GAM value obtained from the crystal orientation analysis data by the SEM-EBSD method is measured in a rectangular region defined by the weld width of the weld and the thickness of the plate materials in a cross section of the welded portion cut in the direction in which the joined plate materials extend, it is preferable that the area ratio of crystal grains having a GAM value of 0.5° or more and less than 2.0° to all crystal grains present in the measured area is 25% or more.

The GAM (grain average misorientation) value is a value obtained from crystal orientation analysis data obtained by the SEM-EBSD method. In crystal grains that are separated by large-angle grain boundaries with an orientation difference of 15° or more, the distance between measurement points (hereinafter also referred to as the step size) is measured at 0.1 μm, the orientation difference between adjacent measurement points is calculated, and the calculated orientation difference is calculated as the average value within the same crystal grain.

A small GAM value means that the average orientation difference within the grains is small, the grains are uniform with very little distortion, and there is a continuous orientation gradient, and indicates that the local distortion within each grain is small. On the other hand, a large GAM value means that the average orientation difference within the grains is large, and indicates that the local distortion within each grain is large. Grains with a GAM value of 0.5° or more and less than 2.0° are grains with characteristics between these two, and indicate that there is a certain degree of local distortion within each grain. Note that when a sheet material is annealed, the GAM value is usually 0° or more and less than 0.5°, and the local distortion within each grain is small.

In this way, if the area ratio of crystal grains with the GAM value of 0.5° or more and less than 2.0° is 25% or more, that is, if the area ratio of crystal grains with a certain degree of large local strain within one crystal grain is 25% or more, the Vickers hardness of the weld can be 65 or more in the case of pure Cu.

In addition, when the area ratio of the crystal grains having the GAM value of 0.5° or more and less than 2.0° is 25% or more, in the case of a Cu alloy, the ratio of the Vickers hardness of the welded part to the plate material (Vickers hardness of the welded part/Vickers hardness of the plate material) can be 0.5 or more. In the case of a Cu alloy, the alloy components Ag, Fe, Ni, Co, Si, Cr, Sn, Zn, Mg, and P are included, so that the hardness of the plate material is increased through solid solution strengthening. In such a plate material made of a Cu alloy, the difference in hardness between the welded part and the plate material tends to be large, but when the area ratio of the crystal grains having the GAM value of 0.5° or more and less than 2.0° is 25% or more, the difference in hardness between the welded part and the plate material can be reduced.

The above GAM value is preferably such that the area ratio of crystal grains with an angle of 0.5° or more and less than 2.0° is 45% or more, and more preferably 65% or more. In addition, the upper limit of the area ratio of crystal grains with an angle of 0.5° or more and less than 2.0° is not particularly limited, but is, for example, 95% or less, and preferably 90% or less.

The GAM value can be obtained from crystal orientation analysis data calculated using analysis software (OIM Analysis, manufactured by TSL) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning analytical electron microscope (JSM-7001FA, manufactured by JEOL Ltd.). "EBSD" is an abbreviation for Electron Backscatter Diffraction, and is a crystal orientation analysis technique that utilizes reflected electron Kikuchi diffraction that occurs when an electron beam is irradiated on a copper plate material, which is a sample, in a scanning electron microscope (SEM). "OIM Analysis" is analysis software for data measured by EBSD.
In the present invention, the measurement region is the entire rectangular region defined by the weld width of the weld and the thickness of the plate material on the surfaces of the cross sections A, A ₁ , and A ₂ mirror-finished by electrolytic polishing. The area ratio of crystal grains having GAM values within a predetermined range can be calculated from the sum of the area ratios of crystal grains in each division of the entire SEM image obtained by the SEM-EBSD method, with GAM values of 0° or more and less than 0.25° as the first division, 15 divisions at 0.25° intervals, and GAM values of 0° or more and less than 3.75° as the measurement targets.

The Cu sheet material used in this electrical/electronic device part is preferably a Cu alloy containing 90% by mass or more of Cu and other metal elements, or pure Cu which is 99.96% by mass or more of Cu and unavoidable impurities. By using a Cu sheet material containing 90% by mass or more, thermal conductivity can be provided. Cu originally has high thermal conductivity, but the thermal conductivity decreases as the amount of added elements increases and as a second phase appears. Therefore, the Cu sheet material used in the electrical/electronic device part of this embodiment contains 90% by mass or more of Cu, which suppresses the decrease in thermal conductivity and provides high strength.

Next, the reasons for limiting the suitable composition of the plate material constituting the electric/electronic device part of the present invention will be explained below.
The sheet material constituting the electric/electronic device part of the present invention may be any sheet material containing 90 mass % or more of Cu, and may be either a Cu alloy or pure Cu.

First, the composition of the plate material when it is a Cu alloy will be described.
(1) When the plate material is a Cu alloy, it is preferable that the plate material contains one or more elements selected from the group consisting of Ag, Fe, Ni, Co, Si, Cr, Sn, Zn, Mg and P.

(Ag: 0.05 to 5.00% by mass)
Ag (silver) is a component that has the effect of improving mechanical properties without impairing electrical properties, and in order to exert such an effect, it is preferable that the Ag content is 0.05 mass% or more. In addition, although there is no particular need to set an upper limit for the Ag content, since Ag is expensive, it is preferable to set the upper limit for the Ag content to 5.0 mass% from the viewpoint of material costs.

(Fe: 0.05 to 0.50 mass%)
Fe (iron) is a component that has the effect of improving mechanical properties. In order to exert such an effect, it is preferable that the Fe content is 0.05 mass% or more. However, even if Fe is contained in an amount of more than 0.50 mass%, no further improvement effect can be expected, and there is a concern that the corrosion resistance may decrease. For this reason, the Fe content is preferably 0.05 to 0.50 mass%.

(Ni: 0.05 to 5.00 mass%)
Ni (nickel) is a component that precipitates finely in the Cu matrix as second-phase particle precipitates consisting of a simple substance or a compound with Si, for example, with a size of about 50 to 500 nm, and these precipitates suppress dislocation movement, thereby causing precipitation hardening, and further has the effect of increasing material strength by suppressing grain growth and refining crystal grains. In order to exert such an effect, it is preferable to set the Ni content to 0.05 mass% or more. On the other hand, if the Ni content exceeds 5.00 mass%, the decrease in electrical conductivity and thermal conductivity becomes significant, so that the upper limit of the Ni content is preferably set to 5.00 mass%.

(Co: 0.05 to 2.00 mass%)
Co (cobalt) is a component that precipitates finely in the Cu matrix as second-phase particle precipitates consisting of a simple substance or a compound with Si, for example, with a size of about 50 to 500 nm, and these precipitates suppress dislocation movement, thereby causing precipitation hardening, and furthermore, has the effect of increasing material strength by suppressing grain growth and refining crystal grains. In order to exert such an effect, it is preferable to set the Co content to 0.05 mass% or more. On the other hand, if the Co content exceeds 2.00 mass%, the decrease in electrical conductivity and thermal conductivity becomes significant, so that the upper limit of the Co content is preferably set to 2.00 mass% or less.

(Si: 0.05 to 1.10 mass%)
Silicon (Si) is an important component that is finely precipitated as a precipitate of second phase particles made of a compound together with Ni, Co, etc. in the parent phase (matrix) of Cu, and this precipitate suppresses dislocation movement, thereby causing precipitation hardening, and furthermore, has the effect of suppressing grain growth and refining crystal grains to increase material strength. In order to exert such an effect, it is preferable to set the Si content to 0.05 mass% or more. On the other hand, if the Si content exceeds 1.10 mass%, the decrease in electrical conductivity and thermal conductivity becomes significant, so it is preferable to set the upper limit of the Si content to 1.10 mass%.

(Cr: 0.05 to 0.50 mass%)
Cr (chromium) is a component that precipitates finely in the Cu matrix as a compound or a simple substance in the form of precipitates with a size of, for example, about 10 to 500 nm, and these precipitates suppress dislocation movement, thereby causing precipitation hardening, and further suppressing grain growth and refining crystal grains, thereby increasing material strength. In order to exert this effect, it is preferable to set the Cr content to 0.05 mass% or more. Furthermore, if the Cr content exceeds 0.50 mass%, the decrease in electrical conductivity and thermal conductivity becomes significant, so the Cr content is preferably set to 0.05 to 0.50 mass%.

(Sn: 0.05 to 9.50 mass%)
Sn (tin) is a component that dissolves in the Cu matrix and contributes to improving the strength of the Cu alloy, and the Sn content is preferably 0.05% by mass or more. On the other hand, if the Sn content exceeds 9.50% by mass, embrittlement is likely to occur. For this reason, the Sn content is preferably 0.05 to 9.50% by mass. In addition, since the inclusion of Sn tends to reduce the electrical conductivity and thermal conductivity, in order to suppress the reduction in electrical conductivity and thermal conductivity, it is more preferable to set the Sn content to 0.05 to 0.50% by mass.

(Zn: 0.05 to 0.50% by mass)
Zn (zinc) is a component that has the effect of improving the adhesion and migration properties of Sn plating and solder plating. To exert such an effect, the Zn content is preferably 0.05 mass% or more. On the other hand, if the Zn content exceeds 0.50 mass%, the amount of zinc vapor increases during welding, which may cause defects in the welded portion. For this reason, the Zn content is preferably 0.05 to 0.50 mass%.

(Mg: 0.01 to 0.50% by mass)
Mg (magnesium) is a component that has the effect of improving mechanical properties. To exert such an effect, the Mg content is preferably 0.01 mass% or more. On the other hand, if the Mg content exceeds 0.50 mass%, the electrical conductivity and thermal conductivity tend to decrease. For this reason, the Mg content is preferably 0.01 to 0.50 mass%.

(P: 0.01 to 0.50% by mass)
P (phosphorus) not only contributes to the deoxidization of Cu alloys, but also finely precipitates with Fe, Ni, etc. in the form of precipitates of about 20 to 500 nm in size as a compound, and these precipitates suppress dislocation movement, thereby causing precipitation hardening, and further suppressing grain growth and refining crystal grains, thereby increasing material strength. In order to exert such an effect, it is preferable that the P content be 0.01 mass% or more. On the other hand, if the P content exceeds 0.50 mass%, cracks tend to easily occur in the solidified part after welding. For this reason, the P content is set to 0.01 to 0.50 mass%.

(2) When the plate material is pure Cu with excellent electrical conductivity and heat dissipation properties: It is preferable that the plate material is pure Cu having a composition that is 99.96% or more Cu and that contains, as unavoidable impurities, for example, Cd, Mg, Pb, Sn, Cr, Bi, Se, and Te at a total content of 5 ppm or less, and Ag and O at a content of 400 ppm or less each.

(Manufacturing method for electrical and electronic equipment parts)
One embodiment of the present invention relates to a method for manufacturing an electric/electronic device part, and includes a welding process in which a plurality of plate materials containing 90% or more by mass are set in an abutted or overlapping state, and then the portions to be joined are irradiated with a first laser beam having a wavelength of 400 to 500 nm with a spot diameter of 100 to 500 μm, and a second laser beam having a wavelength of 800 to 1200 nm with a spot diameter of 10 to 300 μm, while welding is performed while spraying an inert gas containing 1 to 50 ppm oxygen at a flow rate of 10 to 50 L/min onto the molten portion, thereby linearly joining and integrating the plurality of plate materials together.
According to this welding process, it is possible to easily weld Cu plate materials together, which was previously difficult, and also to achieve a Vickers hardness of 60 or more at the weld, thereby obtaining a weld with high strength.

(Laser welding method)
Laser welding is a welding method that uses a highly directional and highly focused wavelength of light collected by a lens, and uses a laser beam with an extremely high energy density as a heat source. By adjusting the output of the laser beam, it is possible to create a penetration weld with a narrow width relative to its depth. Laser beams can also be focused much smaller than the arc used in arc welding. With energy densified by a collecting lens, laser welding equipment can perform localized welding and join materials with different melting points. It is also suitable for fine welding, as there is little thermal effect from welding, the weld pattern is thin, and no processing reaction force is generated.

(Laser welding equipment)
FIG. 6 is a diagram showing an example of a schematic configuration of a laser welding apparatus. The laser welding apparatus 20 includes a laser control unit 21, oscillators 221 and 222, a laser head 29, a processing table (not shown), and a gas supply nozzle 30. The Cu plate materials 111 and 112, which are the workpieces, are arranged on the processing table in a butted or overlapped state. The laser control unit 21 controls the laser oscillators 221 and 222 that oscillate the laser light, a scanner (not shown), the laser head 29, the processing table, and the like. The control unit 21 controls the direction of travel of the Cu plate materials 111 and 112, which are the workpieces, by controlling, for example, the rotation of an X-axis motor and a Y-axis motor (not shown). The control unit 21 may also move and control the laser beams 231 and 232. This can be appropriately selected depending on the size of the workpiece. The control unit 21 oscillates a plurality of first and second laser beams 231 and 232 oscillated from the oscillators 221 and 222. The oscillated first and second laser beams 231, 232 are collected into parallel beams by the first and second condenser lenses 261, 262 in the laser head 29 through the glass fiber 25. The first and second laser beams 231, 232 are redirected toward the processing table by the first and second mirrors 271, 272, and the first and second laser beams 231, 232 are focused and irradiated through the focusing lens 28 at the positions to be joined of the Cu plate materials 111, 112, thereby performing welding. At this time, an inert gas is supplied from the gas supply nozzle 30 to prevent oxidation caused by heating by the laser beam. The inert gas can be appropriately selected from argon, helium, nitrogen, and the like.

The laser can be appropriately selected from among those known as welding lasers. Examples of the laser include _CO2 laser, Nd:YAG laser, semiconductor laser, fiber laser, etc. It is preferable to use a fiber laser in terms of output and focusing of laser light. Other configurations of the laser welding device can be selected from any conventionally known configurations.

(Laser welding)
FIG. 7 is a diagram showing the spot diameter of the laser beam of the laser welding device. As shown in FIG. 7, the first laser beam 231 having a wavelength of 400 to 500 nm is irradiated with a spot diameter of 100 to 500 μm. Then, the second laser beam 232 having a wavelength of 800 to 1200 nm is irradiated with a spot diameter of 10 to 300 μm. FIG. 7 shows an example in which the first laser beam 231 and the second laser beam 232 are irradiated so as to overlap on the plate surface. By simultaneously irradiating a plurality of laser beams having specific wavelengths and spot diameters, it has become possible to easily weld Cu plate materials, which was previously difficult. In addition, by welding while spraying an inert gas containing 1 to 50 ppm of oxygen to the molten part at 10 to 50 L/min, a welded part having a Vickers hardness of 60 or more can be obtained.

The inert gas sprayed on the molten part contains 10 to 50 ppm of oxygen. Examples of inert gas include nitrogen gas and argon gas. By laser welding while spraying such an inert gas containing 10 to 50 ppm of oxygen at a flow rate of 10 to 50 L/min, the molten part is covered with the inert gas and an appropriate amount of oxygen can be sent to the inside of the molten part, which generates fine oxides to increase the hardness of the welded part, and it is presumed that the rapid cooling introduces an appropriate amount of strain into the crystal grains. If the oxygen content of the inert gas is less than 10 ppm, sufficient oxygen cannot be supplied, which may result in low hardness. On the other hand, if it exceeds 50 ppm, excessive oxidation of the inside may occur, causing embrittlement. In addition, if the flow rate of the inert gas containing 10 to 50 ppm of oxygen is less than 10 L/min, sufficient shielding effect cannot be obtained, oxidation progresses excessively, and the cooling rate of the molten part decreases, so sufficient strain cannot be obtained inside the crystals. Furthermore, if the flow rate exceeds 50 L/min, a large amount of gas will be blown onto the molten area, which can cause the shape of the molten pool to become unstable and lead to poor solidification.

(Application to electrical and electronic equipment)
The electrical/electronic device part of the present invention can be considered to be used in semiconductor devices, LSIs, or many electronic devices using these. Furthermore, the part can be used in electrical/electronic devices such as home game machines, medical devices, workstations, servers, personal computers, car navigation systems, mobile phones, robot connectors, battery terminals, jacks, relays, switches, autofocus camera modules, lead frames, etc., which are particularly required to be miniaturized and highly integrated.

(Vapor chamber)
The electric/electronic device part of the present invention is made of pure Cu or a Cu alloy having excellent thermal conductivity, and is also strong and resistant to deformation, so that it is preferably applied to heat pipes and vapor chambers.

(Busbar)
In addition, the electric/electronic device part of the present invention is made of pure Cu or a Cu alloy having excellent thermal conductivity, and has high strength and excellent deformation resistance, and is therefore suitable as a bus bar. The bus bar can be used as an electrical path for electrical connection or a transport path for heat dissipation, and in particular, can be used as a cooling device by connecting a heat generating part to a heat dissipation part or to the outside through the bus bar to provide a path.

Examples of the present invention will be described below. The present invention can be embodied in various ways, and is not limited to the following examples. Examples 4, 9, 11, 13, 15, 17, 19, 21, 23, 25, and 27 to 33 are to be read as reference examples.

(Examples 1 to 6 and Comparative Examples 1 to 9) Joining of two identical plates made of pure Cu In Examples 1 to 5 and Comparative Examples 1 to 9, two plates made of pure Cu having the composition shown in Table 1 were cut out to a thickness of 0.15 mm, a width of 20 mm, and a length of 1000 mm. The two cut-out plates were moved in a direction in which the end faces extending in the length direction were brought closer to each other, and arranged in a butted state as shown in FIG. 1(a). Then, a first laser beam having a wavelength of 400 to 500 nm and a spot diameter (hereinafter sometimes referred to as "beam diameter") of 100 to 500 μm and a second laser beam having a wavelength of 800 to 1200 nm and a spot diameter of 10 to 300 μm were irradiated while sweeping at 100 to 400 mm/sec while maintaining the positional relationship of the spot diameter as shown in FIG. 7, thereby performing laser welding. The laser conditions are shown in Table 1. Laser welding was performed while supplying an inert gas containing oxygen as shown in Table 1 to the molten part. As the inert gas, a mixture of G1 grade nitrogen gas manufactured by Taiyo Nippon Sanso and oxygen gas was used.
In Example 6, instead of the butt joint arrangement, a superimposed arrangement as shown in FIG. 1B was used, and laser welding was performed under the same conditions as in Example 1.

The Vickers hardness and GAM value of the welded portion were then measured by the following method. The results are shown in Table 1. In Table 1, when the area ratio of crystal grains with a Vickers hardness of 60 or more and a GAM value of 0.5° or more and less than 2.0° to all crystal grains present in the measured area is 25% or more, the deformation resistance is excellent and is recorded as "◎", when the area ratio of crystal grains with a Vickers hardness of 60 or more and a GAM value of 0.5° or more and less than 2.0° to all crystal grains present in the measured area is less than 25%, the deformation resistance is good and is recorded as "◯", and when the Vickers hardness is less than 60, the deformation resistance is poor and is recorded as "×".

[Vickers hardness]
The Vickers hardness HV was measured according to the method specified in JIS Z2244 (2009). The load (test force) was selected from the range of 20 to 100 gf so that the diagonal length of the indentation did not exceed 0.03 mm. The pressing time (pressing time) of the indenter was 15 sec.
In Examples 1 to 5 and Comparative Examples 1 to 9 in which the plate materials were butted together, as shown in Fig. 1(a), the welding direction was the X-axis direction, the direction perpendicular to the welding direction was the Y-axis direction, and the normal direction of the plate materials was the Z-axis direction, and the Vickers hardness was measured at a position b corresponding to half the dimension of the thickness a of the plate material at the welded portion present at a cross section A when the welded portion was cut in the Y-axis direction. Measurements were performed at five cross sections A (YZ planes) cut at intervals of 1 mm in the welding direction (X-axis direction), and the Vickers hardness was calculated as the average value of the measurement results.
In Example 6 in which the plate materials were overlapped, the Vickers hardness was measured at a position b1 corresponding to half the dimension of the thickness a1 of the plate material ₁ of the welded portion present on a cross section A1 when the welded portion is cut in the Y-axis direction, and at a position _b2 corresponding to half the dimension of the thickness _a2 of the plate material ₂ of the welded portion present on a cross section _A2 when the welded portion is cut in the Y-axis direction, as shown in Fig. 1(b ₎ . Measurements were performed at five cross sections _A1 and _A2 (YZ planes) cut at intervals of 1 mm in the welding direction (X-axis direction), and the average value of the measurement results was calculated.

[GAM value]
The GAM value was obtained from crystal orientation analysis data calculated using analysis software (TSL, OIM Analysis) from crystal orientation data continuously measured using an EBSD detector attached to a high-resolution scanning analytical electron microscope (JSM-7001FA, manufactured by JEOL Ltd.). The measurement was performed in a field of view of 400 μm × 800 μm with a step size of 0.1 μm. The measurement area is the entire rectangular area defined by the weld width of the weld and the thickness of the plate material on the surfaces of the cross sections A, A ₁ , and A ₂ above, which have been mirror-finished by electrolytic polishing.
The area ratio of crystal grains with GAM values within a specified range was calculated from the sum of the area ratios of crystal grains in each division in the entire SEM image obtained by the SEM-EBSD method, with GAM values of 0° or more and less than 0.25° as the first division, 15 divisions in increments of 0.25°, and GAM values of 0° or more and less than 3.75° as the measurement targets.
In Example 6, the average value of the crystal grain area ratio of the GAM value measured for each of the two plate materials was calculated, and this average value is shown in Table 1.

According to Examples 1 to 6, in joining two identical plates made of pure Cu, a first laser beam having a wavelength of 400 to 500 nm is irradiated with a spot diameter of 100 to 500 μm, and a second laser beam having a wavelength of 800 to 1200 nm is irradiated with a spot diameter of 10 to 300 μm, and an inert gas containing 1 to 50 ppm of oxygen is sprayed into the molten part at a flow rate of 10 to 50 L/min, thereby making it possible to make the Vickers hardness of the welded part 60 or more. Among them, Examples 1 to 3, 5 and 6, in which the area ratio of the crystal grains of the GAM value is 25% or more, had a Vickers hardness of 65 or more, which was particularly high.
On the other hand, Comparative Example 1, in which the oxygen content of the inert gas was less than 10 ppm, had low Vickers hardness. In Comparative Example 2, in which the oxygen content of the inert gas was more than 50 ppm, and Comparative Example 3, in which the flow rate of the inert gas was less than 10 L/min, internal oxidation was excessive, causing embrittlement and large damage. Comparative Example 4, in which the flow rate of the inert gas was more than 50 L/min, caused poor solidification and the thickness of the welded part was greatly reduced. Comparative Examples 5 to 9, in which the laser conditions were not irradiation with a first laser beam having a wavelength of 400 to 500 nm with a spot diameter of 100 to 500 μm and irradiation with a second laser beam having a wavelength of 800 to 1200 nm with a spot diameter of 10 to 300 μm, were unable to join plates made of pure Cu together.

(Examples 7 to 26 and Comparative Examples 18 to 21) Joining of two identical plates made of Cu alloy In Examples 7 to 26 and Comparative Examples 18 to 21, two plates made of Cu alloy having the composition shown in Table 2 were used and welded under the welding conditions shown in Table 2, except that they were the same as in Example 1. The results are shown in Table 2.

According to Examples 7 to 26, in joining two identical plates made of Cu alloy, the Vickers hardness of the welded portion can be made 60 or more by irradiating the first laser light having a wavelength of 400 to 500 nm with a spot diameter of 100 to 500 μm and the second laser light having a wavelength of 800 to 1200 nm with a spot diameter of 10 to 300 μm, and welding while spraying an inert gas containing 1 to 50 ppm of oxygen at a flow rate of 10 to 50 L/min to the molten portion. Among them, Examples 7, 8, 10, 12, 14, 16, 18, 20, 22, 24, and 26, in which the area ratio of the crystal grains of the GAM value is 25% or more, can make the ratio of the Vickers hardness of the welded portion to the plate material (Vickers hardness of the welded portion/Vickers hardness of the plate material) 0.5 or more, and can particularly suppress the decrease in the Vickers hardness of the welded portion.

(Examples 27 to 28) Joining of two plates made of pure Cu with different composition In Example 27, plate materials made of Cu alloy having the composition shown in Table 3 were used, and welding was performed under the welding conditions shown in Table 3, except that the same procedure was followed as in Example 1 (butt welding).
In Example 28, the same procedure as in Example 6 (overlapping) was used, except that plate materials made of Cu alloys having the component compositions shown in Table 3 were used and were welded under the welding conditions shown in Table 3. The plate materials were overlapped so that the plate materials shown in the upper row of Table 3 were the laser irradiated side.
The results are shown in Table 3.

According to Examples 27 to 28, when joining two plates made of pure Cu but with different component compositions, it is found that the Vickers hardness of the weld can be made 60 or more by irradiating a first laser beam having a wavelength of 400 to 500 nm with a spot diameter of 100 to 500 μm and a second laser beam having a wavelength of 800 to 1200 nm with a spot diameter of 10 to 300 μm while welding while spraying an inert gas containing 1 to 50 ppm oxygen into the molten part at a flow rate of 10 to 50 L/min.

(Examples 29 to 31) Joining of two plates made of Cu alloy with different composition Examples 29 to 31 were the same as Example 1, except that plates made of Cu alloy having the composition shown in Table 4 were used and welded under the welding conditions shown in Table 4. The results are shown in Table 4.

According to Examples 29 to 31, in joining two plates made of Cu alloy and having different component compositions, it is found that the Vickers hardness of the welded portion can be made 60 or more by irradiating a first laser beam having a wavelength of 400 to 500 nm with a spot diameter of 100 to 500 μm and a second laser beam having a wavelength of 800 to 1200 nm with a spot diameter of 10 to 300 μm while welding while spraying an inert gas containing 1 to 50 ppm oxygen into the molten portion at a flow rate of 10 to 50 L/min.

(Examples 32 to 33) Joining of a plate material made of pure Cu and a plate material made of a Cu alloy In Example 32, a plate material made of pure Cu and a plate material made of a Cu alloy having the component composition shown in Table 5 were used, and welding was performed under the welding conditions shown in Table 5. Other than that, the same procedure was followed as in Example 1 (butt welding).
In Example 33, a plate material made of pure Cu and a plate material made of a Cu alloy having the component composition shown in Table 5 were used, and welding was performed under the welding conditions shown in Table 5. The other conditions were the same as in Example 6 (overlapping). Note that the first plate material shown in the upper row of Table 5 was overlapped so as to be the laser irradiated side.
The results are shown in Table 5.

According to Examples 32 and 33, in joining a plate material made of pure Cu and a plate material made of a Cu alloy, by irradiating a first laser beam having a wavelength of 400 to 500 nm with a spot diameter of 100 to 500 μm and irradiating a second laser beam having a wavelength of 800 to 1200 nm with a spot diameter of 10 to 300 μm, and by welding while spraying an inert gas containing 1 to 50 ppm oxygen into the molten part at a flow rate of 10 to 50 L/min, it is found that the Vickers hardness of the welded part can be made 60 or more.

Reference Signs List 1, 2 Plate material 3, 3A, 3B, 3C Welded part 10, 10A, 10B, 10C Joint 20 Laser welding device 21 Laser control unit 25 Glass fiber 26 Condenser lens 28 Focusing lens 29 Laser head 30 Gas supply nozzle 221, 222 Laser oscillator 231 First laser beam 232 Second laser beam 261 First condenser lens 262 Second condenser lens 271 First mirror 272 Second mirror

Claims (5)

The plate is made up of a plurality of plate materials having the same composition and containing 90% by mass or more of Cu.
The plurality of plate materials are joined together linearly or in points by welding in a butted or overlapped state, and are integrated together.
The weld extends through the entire thickness of the plate,
In a cross section when the welded portion is cut in a direction in which the joined plate materials extend,
The weld has a Vickers hardness of 60 or more when measured at a position corresponding to half the thickness of the plate material,
A part for electric/electronic equipment, in which, when a GAM value obtained from crystal orientation analysis data by a SEM-EBSD method is measured in a rectangular region in the cross section defined by the weld width of the weld and the thickness of the plate material, crystal grains having a GAM value of 0.5° or more and less than 2.0° account for an area ratio of 25% or more to all crystal grains present in the measured area . 2. The part for electrical and electronic equipment according to claim 1 , wherein the plate material contains one or more elements selected from the group consisting of Ag, Fe, Ni, Co, Si, Cr, Sn, Zn, Mg and P. The component for electrical and electronic equipment according to claim 1 or 2, wherein the plate material is 99.96 mass% or more of Cu and unavoidable impurities. The part for electric/electronic equipment according to any one of claims 1 to 3 , wherein the part for electric/electronic equipment is a vapor chamber. The part for electric/electronic devices according to any one of claims 1 to 3 , wherein the part for electric/electronic devices is a bus bar.

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