Welding structure, electronic component module, and welding method

Abstract

To suppress crack in a welded structure, by, for example, reducing residual stress caused by welding.SOLUTION: A welded structure (2) includes a first component (4) having a first joint surface part (10), a second component (6) having a second joint surface part (16), and a weld solidification part (8) formed by welding on each joint surface part of the butted first component and second component. The weld solidification part contains a first solidification part (20) arranged outside, and a second solidification part (22) arranged inside.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology of the present disclosure relates to a welding structure, an electronic component module, and a welding method. In this specification, the claims, and the abstract, the term "welding structure" is used as a term encompassing the welding structure itself and welded structures.

Background Art

[0002] Welding is used for connecting members, for example, electrical connections in electronic components. For example, it is known that the electrode terminals of a battery pack are welded to a bus bar (for example, Patent Document 1). In electronic components, welding can reduce electrical resistance compared to fastening with fastening members such as bolts and screws, and can suppress energy loss and heat generation. However, welding is less prone to connection or separation than fastening with fastening members.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the members used for welding are selected in consideration of selection items such as, for example, the use of the members, their suitability for welding, and their compatibility with the mating members for welding. In the selection of members, for example, if the use of the members is set as a priority selection item, compromises may be necessary regarding other selection items such as their suitability for welding and their compatibility with the mating members.

[0005] When a bus bar having high strength is bolted to another member, the change in the thickness of the bus bar over time is small, and loosening of the bolts can be suppressed. However, when the strength of the bus bar increases, there is a problem that cracks are likely to occur generally by welding. Here, this "strength" refers to the resistance of the material to deformation and destruction.

[0006] In electronic components, large cracks in electrical connection members such as bus bars responsible for electrical connection cause problems such as an increase in electrical resistance and heat generation during energization.

[0007] Patent Document 1 does not disclose or suggest such problems, and the configuration disclosed in Patent Document 1 cannot solve such problems.

[0008] Therefore, a first object of the present disclosure is to reduce residual stress due to welding and suppress cracks in a welded structure, for example.

[0009] A second object of the present disclosure is to reduce residual stress due to welding and expand the types of members that can be used for welding, for example.

[0010] A third object of the present disclosure is to improve performance or specifications such as electrical characteristics, strength, hardness, and durability in a welded structure by utilizing the expansion of the range of available members, for example.

Means for Solving the Problems

[0011] To achieve the above object, according to a first aspect of the present disclosure, a welded structure includes a first member having a first joint surface portion, a second member having a second joint surface portion, and a weld solidified portion formed by welding on the joint surface portions of the first member and the second member that are abutted, and the weld solidified portion , the a first solidified portion, and first solidified portion's a second solidified portion formed inside formed by remelting the first solidified portion and includes.

[0012] In the above welding structure, the second member may have a higher strength than the first member, and the welding center portion of the weld solidification portion may be disposed on the first member side with respect to the butting surface of the first member and the second member.

[0013] In the above welding structure, the second member may further include a fastening portion that can be fastened to another member.

[0014] In the above welding structure, the width of the cross section of the second solidification portion may be 10% or more and 70% or less of the width of the cross section of the weld solidification portion.

[0015] In the above welding structure, the weld solidification portion may have an annular shape. In this specification and the claims, the term "ring" represents an object having a shape obtained by connecting both ends of a line or an elongated surface. The ring may be an annular ring having a circular shape, or may have a shape other than a circular shape.

[0016] To achieve the above object, according to a second aspect of the present disclosure, an electronic component module has the above welding structure.

[0017] To achieve the above object, according to a third aspect of the present disclosure, a welding method includes melting an adjacent portion of a first member and a second member adjacent to each other by a first heating to form a molten portion, and cooling the molten portion; and re-melting or reheating a part of the molten portion by a second heating to , the form a first solidification portion and , the first solidified portion's form a second solidification portion inside formed by remelting or reheating the first solidified portion to form a weld solidification portion including the second solidification portion.

[0018] In the above welding method, the second member may have a higher strength than the first member, and the first heating may be applied to the first member side with respect to the butting surface of the first member and the second member.

[0019] The above welding method may further include a step of forming a fastening portion that can be fastened to another member on the second member.

[0020] In the above welding method, the amount of heat applied by the second heating may be 9% or more and 50% or less of the amount of heat applied by the first heating.

[0021] In the above welding method, the first heating and the second heating may be applied on the circumference, and the welded solidified portion may have an annular shape.

[0022] In the above welding method, the first member may be a terminal of an electronic component or a conductive member connectable to the electronic component. The second member may be an electrical connection member capable of electrically connecting the first member to another member.

Advantages of the Invention

[0023] According to the technology of the present disclosure, any of the following effects can be obtained.

[0024] (1) Since the welded solidified portion includes a first solidified portion disposed on the outside and a second solidified portion disposed on the inside, the residual stress in the welded solidified portion is suppressed, and cracking in the butt joint of the welded structure can be suppressed. Therefore, for example, in an electronic component, an increase in electrical resistance due to cracking and heat generation during energization can be suppressed.

[0025] (2) Since the residual stress in the welded solidified portion is suppressed, the degree of freedom in the types of members connected by the butt joint can be expanded.

[0026] (3) The members connected by the butt joint can be selected, for example, based on the use of the members, and the performance or specifications of the welded structure can be improved. For example, in the welded structure of an electronic component, a member with low resistance and high strength can be selected in consideration of conductivity and fastening to other members.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0028] FIG. 1 shows an example of a welding structure according to an embodiment. FIG. 2 shows an example of a cross-section of a weld solidification part and shows a cross-section taken along line II-II at A in FIG. 1. The configurations shown in FIGS. 1 and 2 are examples, and the technology of the present disclosure is not limited to such configurations.

[0029] The welding structure 2 is formed by a welding method such as laser welding. The welding structure 2 includes a first member 4, a second member 6, and a weld solidification part 8.

[0030] The first member 4 is, for example, a terminal of an electronic component such as a power storage device module or a conductive member connectable to an electronic component. The electronic component may be a single electronic component or an electronic component module formed by a plurality of electronic components being assembled and connected. The first member 4 has, for example, a cylindrical shape or a substantially cylindrical shape and has a first joint surface portion 10 on the end side surface. The first joint surface portion 10 forms a joint surface portion with respect to the weld solidification part 8. The first member 4 includes a metal such as aluminum, an aluminum alloy, or stainless steel. The first member 4 may be a metal such as aluminum, an aluminum alloy, or stainless steel.

[0031] Aluminum is pure aluminum (1000 series material) having a purity of 99.0% or more, for example, and has excellent workability, surface treatability, and corrosion resistance. Aluminum alloys include, for example, aluminum-copper (Al-Cu) based alloys (2000 series materials), aluminum-manganese (Al-Mn) based alloys (3000 series materials), aluminum-silicon (Al-Si) based alloys (4000 series materials), aluminum-magnesium (Al-Mg) based alloys (5000 series materials), aluminum-magnesium-silicon (Al-Mg-Si) based alloys (6000 series materials), aluminum-zinc-magnesium (Al-Zn-Mg) based alloys (7000 series materials), and the like. Aluminum-copper based alloys have high strength and excellent machinability. Aluminum-manganese based alloys have workability and corrosion resistance and have higher strength than pure aluminum. Aluminum-silicon based alloys have excellent heat resistance and wear resistance and have a small coefficient of thermal expansion. Aluminum-magnesium based alloys have excellent corrosion resistance and workability and have high strength. Aluminum-magnesium-silicon based alloys have excellent corrosion resistance and high strength. Aluminum-zinc-magnesium based alloys have high strength.

[0032] The second member 6 is, for example, an electrical connection member such as a bus bar and can electrically connect the first member 4 to other members, for example. The second member 6 has, for example, a plate shape or substantially a plate shape. The second member 6 includes a metal such as the aforementioned aluminum alloy or stainless steel, for example. The second member 6 may be a metal such as the aforementioned aluminum alloy or stainless steel. The second member 6 is, for example, a member that suppresses deformation due to creep. Creep is a phenomenon in which the deformation of an object increases with time when a stress of a certain magnitude is acting. Generally, the deformation due to creep of a member with high strength is small, and a member with high strength suppresses the deformation due to creep. The second member 6 may be made of the same material as the first member 4, or may be made of a material different from the first member 4, for example, a material having higher strength than the first member 4.

[0033] The second member 6 includes a fusion connection part 12 and a fastening part 14. The fusion connection part 12 includes a second joint surface part 16 for the welding solidification part 8. The second joint surface part 16 is arranged on an annulus such as on the circumference, and the end of the first member 4 is inserted inside the second joint surface part 16. The first joint surface part 10 of the first member 4 is arranged on the extension of the second member 6 having a plate shape or a substantially plate shape. The fastening part 14 includes, for example, a fastening hole 18 and can be fastened to other members by a fastening member such as a bolt or a screw. The second member 6 has a strength high enough to suppress loosening of the fastening member, for example, and suppresses loosening of the fastening member.

[0034] The welding solidification part 8 is arranged between the first joint surface part 10 of the first member 4 and the second joint surface part 16 of the second member 6, joins the first joint surface part 10 and the second joint surface part 16, and forms a butt joint. The welding solidification part 8 is formed by the solidification of the first member 4 and the second member 6 (hereinafter referred to as "members 4, 6") melted during welding and is a mixed member of members 4, 6. The welding solidification part 8 has, for example, a semi-elliptical or substantially semi-elliptical cross-sectional shape. The welding solidification part 8 includes a first solidification part 20 and a second solidification part 22. The welding solidification part 8 has, for example, an annular shape on the exposed surface as shown in A of FIG. 1.

[0035] The first solidification part 20 is arranged outside the welding solidification part 8, that is, in the peripheral part of the welding. The first solidification part 20 contacts and joins the first joint surface part 10 and the second joint surface part 16 and connects the first member 4 to the second member 6. For example, the first solidification part 20 is formed when the members 4, 6 melted by the first heating such as the first laser irradiation are cooled. The cooling of the members 4, 6 may be natural cooling or mild forced cooling, for example.

[0036] The second solidified portion 22 is disposed inside the welded solidified portion 8, that is, at the welding center portion P of the weld and in the vicinity of the welding center portion P. The welding center portion P is the elliptical center of the welded solidified portion 8 having a semi-elliptical or substantially semi-elliptical cross-sectional shape, and coincides or substantially coincides with the heating point of the weld. For example, a part of the members 4 and 6 cooled after melting is remelted and recooled by a second heating such as a second laser irradiation, and the second solidified portion 22 is formed. The recooling after the second heating may be, for example, natural cooling or mild forced cooling.

[0037] The welded solidified portion 8 has residual stress. Residual stress is the stress that remains in an object even after the external force is removed after the object has been subjected to the action of an external force. For example, residual stress is generated when an object heated in heat treatment is cooled. Also, in the heat treatment of dissimilar members, if the mixing of the dissimilar members is non-uniform, the composition of the material becomes non-uniform and residual stress is generated.

[0038] The heated welded portion is cooled from the periphery of the welded portion, and finally the central portion of the welded portion is solidified. Therefore, in general welding, the residual stress (tensile stress) becomes high at the central portion of the welded portion. Also, the greater the amount of heat applied during welding and the greater the volume of the member to be melted, the higher the residual stress. However, in the welding structure 2, the second amount of heat applied to the members 4 and 6 in the second heating is suppressed, and the residual stress at the welding center portion P and in the vicinity of the welding center portion P is suppressed. When the second member 6 is made of a different material from the first member 4, the remelting of the members 4 and 6 promotes the mixing of the members 4 and 6, and the residual stress due to the non-uniformity of the material can be suppressed. That is, even if the second member 6 and the first member 4 are made of different materials, it is possible to suppress the residual stress and maintain a stable connection structure.

[0039] The width W2 of the cross-section of the second solidified portion 22 is, for example, 10% or more and 70% or less of the width W1 of the cross-section of the welded solidified portion 8. When the second solidified portion 22 is substantially similar to the welded solidified portion 8, if the width W2 is 70% or less of the width W1, the cross-sectional area of the second solidified portion 22 is suppressed to be half or less of the entire cross-sectional area of the welded solidified portion 8. The second amount of heat becomes 50% or less of the first amount of heat applied to the members 4 and 6 by the first heating, based on the area ratio. Since the second amount of heat is smaller than the first amount of heat, the residual stress in the second solidified portion 22 is suppressed. The residual stress at the welding center portion P of the welded solidified portion 8 and in its vicinity can be suppressed more than the residual stress at the welding center portion P of the welded solidified portion composed only of the first solidified portion 20 and in its vicinity.

[0040] If the width W2 is, for example, 10% or more of the width W1, the second solidified portion 22 will be sufficiently disposed on the surface near the central portion where the residual stress becomes high. That is, the second solidified portion 22 can make the central portion of the exposed surface where cracks are likely to occur less likely to crack. When the second solidified portion 22 is substantially similar to the welded solidified portion 8, if the width W2 is 10% or more of the width W1, the cross-sectional area of the second solidified portion 22 becomes 9% or more of the entire cross-sectional area of the welded solidified portion 8. The second amount of heat becomes 9% or more of the first amount of heat based on the area ratio.

[0041] The welding center portion P is disposed, for example, on the first member 4 side with respect to the butting surface S of the members 4 and 6. The butting surface S is a surface formed by butting the members 4 and 6 before welding. In the welding where the welding center portion P is disposed on the first member 4 side, when the second member 6 has a higher strength than the first member 4, the members 4 and 6 can be welded with less heat than when irradiating the second member 6 with higher strength with a laser, and thus the residual stress can be suppressed. In the welding where the welding center portion P is disposed on the first member 4 side, when the second member 6 has a lower strength than the first member 4, the difference in the melting amount of the members 4 and 6 can be made smaller than when irradiating the second member 6 with lower strength with a laser.

[0042] The welding center P may overlap the butting surface S or may be disposed on the side of the second member 6 with respect to the butting surface S. Welding in which the welding center P overlaps the butting surface S can reduce the difference in the melting amounts of the members 4 and 6.

[0043] FIG. 3 shows an example of a welding method. The inverted triangle symbols shown in FIG. 3B and FIG. 3D represent the irradiation of laser light, and the arrow shown in FIG. 3C represents the direction of the residual stress, indicating that tensile stress exists in the weld solidification portion 8 centered on the central portion of the weld solidification portion 8. The welding method shown in FIG. 3 is an example, and the technology of the present disclosure is not limited to such a method.

[0044] The second member 6 before welding includes, for example, a circular through-hole slightly larger than the end of the first member 4 before welding. The second member 6 may include a plurality of such circular through-holes. When the number of the through-holes increases, high precision is required for the arrangement of the end of the first member 4 and the through-holes, and the manufacturing cost becomes high to achieve high precision. However, since a gap of about 0.1 to 0.5 mm is generated because the through-hole has a diameter about 0.1 to 0.5 mm larger than the end of the first member 4, it is possible to arrange the end of the first member 4 and the through-hole without requiring high precision. As shown in FIG. 3A, the end of the first member 4 is inserted into the through-hole of the second member 6, for example, and the first member 4 is adjacent to the second member 6.

[0045] As shown in FIG. 3B, the adjacent portion 32 of the members 4 and 6 adjacent to each other is melted by first heating such as first laser irradiation to form a melted portion 34. In FIG. 3B, the center of the first heating is disposed on the side of the first member 4 with respect to the butting surface S of the members 4 and 6. Therefore, even if there is a gap of about 0.1 to 0.5 mm between the members 4 and 6, stable connection can be achieved. However, the center of the first heating may overlap the butting surface S or may be disposed on the side of the second member 6 with respect to the butting surface S.

[0046] The first heating relatively moves, for example, circumferentially with respect to members 4 and 6 to melt the adjacent portion 32, for example, annularly. In the relative movement of the first heating, the laser irradiation device may move, or the members 4 and 6 may move. Due to the movement of the heating location, the melted portion 34 is naturally cooled, for example, and a solidified portion 36 is formed as shown in C of FIG. 3.

[0047] As already described, the heated welded portion is cooled from the periphery of the welded portion, and finally the central portion of the weld is solidified. Therefore, the residual stress in the solidified portion 36 becomes high at the central portion of the solidified portion 36 and is generated starting from the central portion of the solidified portion 36.

[0048] As shown in D of FIG. 3, a part of the solidified portion 36 is remelted by a second heating such as a second laser irradiation to form a remelted portion 38. The second heating is applied, for example, to the heating center in the first heating, that is, the width center portion of the solidified portion 36. The second heating may be applied to the side of the first member 4 or the side of the second member 6 with respect to the heating center in the first heating. The second heat quantity is controlled to be less than the first heat quantity, and the residual stress of the second solidified portion 22 (E of FIG. 3) formed by the solidification of the remelted portion 38 can be made smaller than the residual stress of the solidified portion 36 before remelting. That is, the residual stress can be released by remelting the solidified portion 36. The second heat quantity is adjusted to, for example, 9% or more and 50% or less of the first heat quantity, and the width W2 is adjusted to 10% or more and 70% or less of the width W1. The first heat quantity and the second heat quantity are adjusted, for example, by any one of the following adjustments (1) to (6). Adjustment (1): Adjustment of the output of the first laser and the second laser Adjustment (2): Adjustment of the distance from the first laser irradiation device and the second laser irradiation device to the members 4 and 6 Adjustment (3): Adjustment of the incident angles of the first laser and the second laser with respect to the members 4 and 6 Adjustment (4): Adjustment of the heating times of the first heating and the second heating Adjustment (5): Adjustment of the relative movement speeds of the first heating and the second heating with respect to the members 4 and 6 Adjustment (6): A combination of a plurality of adjustments such as Adjustment (1) to Adjustment (5)

[0049] The second heating relatively moves, for example, circumferentially with respect to the members 4 and 6 to remelt the solidified portion 36, for example, annularly. Therefore, the remelted portion 38 is cooled, and a welded solidified portion 8 including the first solidified portion 20 and the second solidified portion 22 is formed as shown in E of FIG. 3.

[0050] The welded structure 2 is manufactured, for example, by the above-described welding method. The manufacturing method of the welded structure is the same as, for example, the above-described welding method, and the description thereof is omitted.

[0051] According to the embodiment, the following operations or effects can be obtained.

[0052] (1) Residual stress generated in the welded portion causes cracks in the welded portion. Residual stress is presumed to be generated, for example, due to the following factors. Factor (1): In laser welding of dissimilar members, the melted members are cooled in a state where they are not sufficiently mixed, resulting in a difference in partial contraction rates. Factor (2): In order to firmly connect the members, a high-power laser is irradiated to form a large welded portion having a large strain. Factor (3): A metal having a high crack sensitivity that easily generates residual stress, for example, an alloy containing magnesium, is used. Factor (4): A welded portion having a shape that causes an increase in residual stress is formed. A welded portion with a curve such as an annular shape has a larger residual stress than a linear welded portion. Factor (5): When the member is surface-treated, the material contained in the surface of the member precipitates during welding, locally reducing the strength of the member.

[0053] Due to the required performance or specifications, it may be difficult to eliminate the above factors (1) to (5). The welded structure 2 can suppress cracks even when factors (1) to (5) exist, and can also suppress cracks in the welding of members selected for the required performance or specifications.

[0054] The welding structure 2 includes a second solidified portion 22 formed by a second amount of heat smaller than the first amount of heat. This second solidified portion 22 has a cross-sectional area smaller than the cross-sectional area of the welding solidified portion 8 and has small residual stress. By forming the second solidified portion 22, the residual stress can be released, canceled, or relaxed. Therefore, a welding structure 2 that is less likely to crack can be obtained.

[0055] (2) Since the welding structure 2 is less likely to crack, the degree of freedom in the combination of members can be expanded.

[0056] (3) Since the welding structure 2 is less likely to crack, members can be selected with emphasis on performance or specifications such as electrical characteristics, strength, hardness, and durability rather than weldability. That is, the performance or specifications of the welding structure 2 can be improved.

Example

[0057] FIG. 4 shows an example of an electronic component according to the example. FIG. 5 shows an example of an end bus bar of the electronic component. The end bus bar 64 is, for example, line-symmetric with respect to a line L shown in A of FIG. 5, and A in FIG. 5 shows an end bus bar with a part omitted. The configurations shown in FIGS. 4 and 5 are examples, and the technology of the present disclosure is not limited to such configurations. In FIGS. 4 and 5, the same parts as those in FIG. 1 are denoted by the same reference numerals. In this example, the installation side of the first holder 56 is referred to as the upper side, and the installation side of the second holder 58 is referred to as the lower side.

[0058] The electronic component 52 is, for example, a power storage device module, and includes a plurality of power storage devices 54, a first holder 56, a second holder 58, a plurality of holder connection members 60, a connection bus bar 62, an end bus bar 64, and a welding solidified portion 8.

[0059] The plurality of power storage devices 54 are, for example, 18 power storage devices 54, and are arranged such that 6 power storage devices 54 arranged in a straight line form 3 rows. That is, the plurality of power storage devices 54 are arranged in 6 rows and 3 columns. The power storage device 54 has a power storage function and is, for example, an electrolytic capacitor or an electric double layer capacitor. The power storage device 54 includes, for example, a cylindrical main body 66 and two electrode terminals 68 protruding from one end surface of the main body 66.

[0060] The electrode terminal 68 is an example of a first member and is, for example, a metal member of pure aluminum (alloy number: 1070), and is excellent in workability, corrosion resistance, weldability, etc. The electrode terminal 68 with excellent corrosion resistance suppresses the chemical reaction with the electrolytic solution and suppresses the influence on the electrical characteristics due to the chemical changes of the electrode terminal 68 and the electrolytic solution. That is, pure aluminum is a material suitable for the electrode terminal 68. The alloy number is, for example, the alloy number shown in Japanese Industrial Standard JIS H4000:2014 "Plates and strips of aluminum and aluminum alloys".

[0061] The first holder 56 is arranged on the power storage device 54. The first holder 56 is a resin member including, for example, a thermoplastic resin, and has terminal holes (not shown) at positions corresponding to the plurality of arranged electrode terminals 68. The terminal holes allow the electrode terminals 68 to pass through, and the ends of the electrode terminals 68 protrude from the upper surface of the first holder 56.

[0062] The second holder 58 is arranged under the power storage device 54. The lower part of the power storage device 54 is fitted into the second holder 58, thereby restricting the movement of the power storage device 54. The second holder 58 is a resin member including, for example, a thermoplastic resin.

[0063] The holder connection member 60 is connected to the first holder 56 and the second holder 58, and maintains the separation distance between the first holder 56 and the second holder 58 at a set distance. The first holder 56, the second holder 58, and the holder connection members 60 at both ends form a frame, and the power storage device 54 is disposed within this frame. The central holder connection member 60 maintains the separation distance between the first holder 56 and the second holder 58 at the set distance at the middle part of the frame. The holder connection member 60 is a resin member containing, for example, a thermoplastic resin.

[0064] The connection bus bar 62 is an example of an electrical connection member, and has, for example, an elongated plate shape and is disposed on the first holder 56 so as to cross three rows of the power storage device 54. The connection bus bar 62 is, for example, welded to the electrode terminals 68 adjacent to each other in each row, and electrically connects the power storage devices 54 adjacent to each other in each row. Further, the connection bus bar 62 connects the welded electrode terminals 68 to the electrode terminals 68 welded in other rows, and electrically connects, for example, six power storage devices 54. The connection bus bar 62 is a member similar to the electrode terminal 68, for example.

[0065] The end bus bar 64 is an example of a second member, and is an electrical connection member capable of electrically connecting the electrode terminal 68 to another member such as a load. The end bus bar 64 has, for example, an elongated plate shape or an elongated substantially plate shape, and is disposed on the first holder 56 so as to cross three rows of the power storage device 54. The end bus bar 64 is welded to the end electrode terminals 68 in each row. Further, the end bus bar 64 connects the welded electrode terminals 68 to the electrode terminals 68 welded in other rows, and electrically connects, for example, three power storage devices 54.

[0066] The end bus bar 64 is a metal member made of, for example, an aluminum-magnesium alloy (alloy number: 5052). The aluminum-magnesium alloy (alloy number: 5052) has excellent corrosion resistance and workability, high strength and hardness, and suppresses deformation due to creep. The aluminum-magnesium alloy (alloy number: 5052) has fluidity and is excellent in cost. When the end bus bar 64 is fastened to other members with fastening members such as bolts and screws, the end bus bar 64 having high strength can suppress loosening of the fastening members.

[0067] The end bus bar 64 includes three fusion connection portions 12 and fastening portions 70. The fusion connection portion 12 includes the second joint surface portion 16 described in the embodiment. The second joint surface portion 16 is arranged on a ring such as a circumference, and the end of the electrode terminal 68 is inserted into the second joint surface portion 16. The first joint surface portion 10 of the electrode terminal 68 is arranged on an extension of the end bus bar 64 having a plate shape or substantially a plate shape. The welding solidification portion 8 is arranged between the first joint surface portion 10 of the electrode terminal 68 and the second joint surface portion 16 of the end bus bar 64, and joins to the first joint surface portion 10 and the second joint surface portion 16 to form a butt joint. The welding solidification portion 8 is the same as the welding solidification portion 8 described in the embodiment, and the description thereof is omitted. The electrode terminal 68, the end bus bar 64, and the welding solidification portion 8 form a welding structure 72, and the electronic component 52 includes the welding structure 72.

[0068] The fastening part 70 includes a plurality of fastening holes 18 and a plurality of fixing holes 74. The fastening holes 18 are, for example, five fastening holes 18 and are used for fastening with other members by a fastening member. The fixing holes 74 are, for example, two fixing holes 74 and are arranged outside the fastening holes 18. The fixing holes 74 are used for fixing the end bus bar 64 to the first holder 56. For example, before the end bus bar 64 is welded to the electrode terminal 68, the end bus bar 64 is fixed to the first holder 56 by the fixing holes 74 and the fixture 76 for positioning. When the end bus bar 64 is fixed to the first holder 56 by the fixing holes 74 and the fixture 76 after welding, stress may be applied to the weld solidification part 8 due to slight deformation of the end bus bar 64 during fixing. Fixing the end bus bar 64 before welding can remove the possibility of applying pressure to the weld solidification part 8 during fixing.

[0069] As shown in FIG. 5, the end bus bar 64 may include other holes, steps, etc. according to the purpose.

[0070] The electronic component 52 may include additional circuits such as a balance circuit, a temperature detection circuit, and a voltage detection circuit (not shown). The additional circuit is connected to, for example, the connection bus bar 62 or the end bus bar 64. In the connection between this additional circuit and the bus bar, a butt joint by the weld solidification part 8 may be used.

[0071] The manufacturing process of the electronic component 52 is an example of a manufacturing method and includes, for example, an assembly process and a welding process.

[0072] In the assembly process, the power storage device 54, the first holder 56, the second holder 58, the holder connection member 60, the connection bus bar 62, the end bus bar 64, and the fixture 76 are combined to obtain a module as shown in FIG. 4.

[0073] In the welding process, for example, the end bus bar 64 is welded to the electrode terminal 68 by the welding method described in the embodiment. The connection bus bar 62 is welded to the electrode terminal 68. In order to form the welding solidification part 8 described above, the connection bus bar 62 may be welded to the electrode terminal 68 by, for example, the welding method described in the embodiment. The description of the welding method described in the embodiment is omitted.

[0074] According to the electronic component according to the embodiment, the following operations or effects can be obtained.

[0075] (1) The operations or effects described in the embodiment can be obtained.

[0076] (2) Even if the end bus bar 64 having high strength and hardness is welded to the electrode terminal 68, cracking of the welding solidification part 8 can be suppressed.

[0077] (3) By suppressing cracking, an increase in electrical resistance and heat generation during energization can be suppressed.

[0078] (4) The electrical stability of the electronic component 52 can be enhanced.

[0079] (5) The end bus bar 64 having high strength and hardness can suppress loosening of the fastening with other members. That is, the thickness of the end bus bar 64 is maintained in a high-temperature environment or over time, so that the axial force of the fastening member is maintained and loosening of the fastening member is suppressed. Therefore, an increase in electrical resistance is suppressed.

[0080] The characteristic items and modification examples of the embodiment or example are listed below.

[0081] (1) In the above-described embodiments and examples, the welded solidified portion 8 has an annular shape on the exposed surface. However, the shape of the welded solidified portion 8 is not limited to an annular shape. For example, the second member 6 or the end bus bar 64 may have an arcuate recess at the end, and this recess may be abutted against the end side surface of the first member 4 or the electrode terminal 68 to form an arcuate welded solidified portion 8. The shape of the upper portion of the first member 4 or the electrode terminal 68 may be other than circular, and the welded solidified portion 8 may have a shape corresponding to the shape of the first member 4 or the electrode terminal 68.

[0082] (2) In the above-described embodiment, the second member 6 includes the fastening portion 14, and in the above-described example, the end bus bar 64 includes the fastening portion 70. However, the second member 6 may not include the fastening portion 14, and the end bus bar 64 may not include the fastening portion 70. The material of the second member 6 or the end bus bar 64 may be restricted for reasons other than loosening of fastening, such as rigidity or scratch resistance.

[0083] (3) In the above-described embodiment, the fastening portion 14 of the second member 6 includes the fastening hole 18. However, as shown in FIG. 6, the fastening portion 14 may include a fastening member 118 such as a male screw, and may be fastened to another member by the fastening member 118. Similar to the embodiment, the fastening portion 70 of the end bus bar 64 may include the fastening member 118, and may be fastened to another member by the fastening member 118.

[0084] (4) In the welding methods of the above-described embodiments and examples, the solidified portion 36 is remelted to form the second solidified portion 22. The welding method is not limited to the welding methods of the embodiments and examples. For example, as shown in C of FIG. 7, during the cooling of the molten portion 34, a second heating may reheat a part of the molten portion 34 to form a reheated portion 138, and as shown in D of FIG. 7, the reheated portion 138 may solidify to form the second solidified portion 22. The cooling may be, for example, natural cooling or mild forced cooling. The reheating of a part of the molten portion 34 can slow down the cooling rate of other parts of the molten portion 34 and suppress the residual stress of the first solidified portion 20.

[0085] (5) In the above embodiment, the electrode terminal 68 is a metal member made of pure aluminum (alloy number: 1070), and the end bus bar 64 is a metal member made of an aluminum-magnesium alloy (alloy number: 5052). However, the electrode terminal 68 is not limited to the aforementioned pure aluminum (alloy number: 1070), and may be, for example, a metal member made of other pure aluminum having a purity of 99% or more. The end bus bar 64 only needs to have a strength sufficient to suppress loosening of the fastening member, and may be, for example, a metal member made of an aluminum alloy selected from aluminum alloys from the 2000 series to the 7000 series, which can suppress loosening of the fastening.

[0086] (6) In the above embodiment, the electronic component 52 includes 18 power storage devices 54. However, the number of power storage devices 54 may be less than 18 or more than 18. Further, the electronic component 52 is not limited to a power storage device module including at least one power storage device 54, and may be other electronic components such as a balance circuit.

[0087] As described above, the most preferred embodiments of the present disclosure have been described. The present disclosure is not limited to the above description, and various modifications and changes can be made by those skilled in the art based on the gist of the invention described in the claims or disclosed in the specification. Needless to say, such modifications and changes are included in the scope of the present disclosure.

Industrial Applicability

[0088] The technology of the present disclosure can be used not only for welding of electronic components such as power storage device modules and circuits but also for welding of various members, and is useful.

Explanation of Reference Numerals

[0089] 2, 72 Welding structure 4 First member 6 Second member 8 Weld solidification part 10 First joint surface part 12 Fused connection part 14, 70 Fastening part 16 Second joint surface part 18 Fastening hole 20 First solidified part 22 Second solidified part 32 Adjacent part 34 Fused part 36 Solidified part 38 Remelted part 52 Electronic component 54 Energy storage device 56 First holder 58 Second holder 60 Holder connection member 62 Connecting bus bar 64 End bus bar 66 Body part 68 Electrode terminal 74 Fixing hole 76 Fixing tool 118 Fastening member 138 Reheating part

Claims

1. a first member having a first joint surface portion; a second member having a second joint surface portion; a weld solidification portion formed by welding on the joint surface portions of the butted first member and second member; comprising; the weld solidification portion includes a first solidification portion and a second solidification portion formed by remelting the first solidification portion inside the first solidification portion, characterized in that it is a welding structure.

2. the second member has higher strength than the first member; the welding center portion of the weld solidification portion is disposed on the first member side with respect to the butting surface of the first member and the second member, characterized in that it is a welding structure according to Claim 1.

3. the second member further includes a fastening portion that can be fastened to another member, characterized in that it is a welding structure according to Claim 1 or Claim 2.

4. the width of the cross-section of the second solidification portion is 10% or more and 70% or less of the width of the cross-section of the weld solidification portion, characterized in that it is a welding structure according to any one of Claims 1 to 3.

5. the weld solidification portion has an annular shape, characterized in that it is a welding structure according to any one of Claims 1 to 4.

6. an electronic component module having the welding structure according to any one of Claims 1 to 5.

7. a step of melting the adjacent portions of the first member and the second member adjacent to each other by first heating to form a molten portion, and cooling the molten portion; a step of forming a weld solidification portion including a first solidification portion and a second solidification portion formed by remelting or reheating a part of the molten portion by second heating, the second solidification portion being formed by remelting or reheating the first solidification portion inside the first solidification portion; characterized in that it is a welding method.

8. the second member has higher strength than the first member; the first heating is applied on the first member side with respect to the butting surface of the first member and the second member, characterized in that it is a welding method according to Claim 7.

9. further comprising a step of forming a fastening portion that can be fastened to another member on the second member, characterized in that it is a welding method according to Claim 7 or Claim 8.

10. the amount of heat applied by the second heating is 9% or more and 50% or less of the amount of heat applied by the first heating, characterized in that it is a welding method according to any one of Claims 7 to 9.

11. the first heating and the second heating are applied on the circumference; The welding method according to any one of claims 7 to 10, wherein the welded and solidified portion has an annular shape.

12. The first member is a terminal of an electronic component or a conductive member connectable to an electronic component, The welding method according to any one of claims 7 to 11, wherein the second member is an electrical connection member capable of electrically connecting the first member to another member.

Images