JP7703983B2 - WELDED STRUCTURE, ELECTRONIC COMPONENT MODULE, AND WELDING METHOD - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a welded structure, an electronic component module, and a welding method. TECHNICAL FIELD In this specification, the claims, and the abstract, the term "welded structure" is used to include a welded structure itself and a welded structure.

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

JP 2015-187910 A

The materials used in welding are selected taking into consideration selection criteria such as the material's intended use, suitability for welding, and compatibility with the mating material. When selecting materials, if the material's intended use is set as a priority selection criteria, compromises may need to be made regarding other selection criteria such as suitability for welding and compatibility with the mating material.

When a high-strength busbar is fastened to another component with bolts, the thickness of the busbar changes little over time, preventing the bolts from loosening. However, as the busbar becomes stronger, there is generally an issue that it is more susceptible to cracks due to welding. Note that "strength" here refers to the material's resistance to deformation and destruction.

In electronic components, large cracks in electrical connection members such as bus bars that provide electrical connections can cause adverse effects such as increased electrical resistance and heat generation when electricity is applied.

Patent Document 1 does not disclose or suggest such a problem, and the configuration disclosed in Patent Document 1 cannot solve such a problem.

Therefore, the first objective of this disclosure is, for example, to reduce residual stress caused by welding and suppress cracking in welded structures.

A second objective of this disclosure is, for example, to reduce residual stress caused by welding and expand the types of components that can be used for welding.

A third object of the present disclosure is to improve the performance or specifications, such as electrical properties, strength, hardness, and durability, of welded structures by utilizing an expanded range of usable materials, for example.

In order to achieve the above-mentioned object, according to a first aspect of the present disclosure, a welded structure comprises a first member having a first joining surface portion, a second member having a second joining surface portion, and a weld solidification portion formed by welding at the joining surfaces of the first and second members which are butted together , the weld solidification portion including a first solidification portion and a second solidification portion formed inside the first solidification portion by remelting the first solidification portion.

In the above welded structure, the second member may have a greater strength than the first member, and the weld center of the weld solidification portion may be located on the first member side relative to the butt surface between the first member and the second member.

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

In the above welded structure, the cross-sectional width of the second solidification portion may be 10% or more and 70% or less of the cross-sectional width of the weld solidification portion.

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

To achieve the above object, according to a second aspect of the present disclosure, the electronic component module has the above-mentioned welded structure.

In order to achieve the above-mentioned object, according to a third aspect of the present disclosure, a welding method includes a step of melting adjacent portions 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 a step of remelting or reheating a portion of the molten portion by a second heating to form a weld solidification portion including a first solidification portion and a second solidification portion formed inside the first solidification portion by remelting or reheating the first solidification portion.

In the above welding method, the second member may have a higher strength than the first member, and the first heat may be applied to the first member side relative to the butt surface between the first member and the second member.

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

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.

In the above welding method, the first heat and the second heat may be applied circumferentially, and the weld solidification portion may have an annular shape.

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

The technology disclosed herein provides one of the following effects:

(1) Because the weld solidification zone includes a first solidification zone arranged on the outside and a second solidification zone arranged on the inside, residual stress in the weld solidification zone is suppressed, and cracks in the butt joint of the welded structure can be suppressed. Therefore, for example, in electronic components, an increase in electrical resistance due to cracks and heat generation when electricity is passed through them can be suppressed.

(2) Residual stress in the weld solidification zone is suppressed, allowing for greater freedom in the types of components that can be connected using butt joints.

(3) The components connected by the butt joint can be selected based on, for example, the application of the components, thereby improving the performance or specifications of the welded structure. For example, in the case of a welded structure for electronic components, a component with low resistance and high strength can be selected taking into account electrical conductivity and fastening with other components.

1 is a diagram showing an example of a welded structure according to an embodiment; FIG. 2 is a diagram showing an example of a cross section of a weld solidification portion. FIG. 1 is a diagram showing an example of a welding method. FIG. 1 is a diagram illustrating an example of an electronic component according to an embodiment. FIG. 2 is a diagram illustrating an example of an end bus bar. FIG. 13 is a diagram showing an example of a welded structure according to a modified example. FIG. 13 is a diagram showing a modified example of a welding method.

Figure 1 shows an example of a welded structure according to an embodiment. Figure 2 shows an example of a cross section of a weld solidification portion, showing a cross section taken along line II-II at A in Figure 1. The configurations shown in Figures 1 and 2 are merely examples, and the technology of the present disclosure is not limited to such configurations.

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

The first member 4 is, for example, a terminal of an electronic component such as an electric storage device module, or a conductive member that can be connected to an electronic component. The electronic component may be a single electronic component, or an electronic component module formed by assembling and connecting multiple electronic components. The first member 4 has, for example, a cylindrical or nearly cylindrical shape, and has a first joint surface 10 on the end side. The first joint surface 10 forms a joint surface for the weld solidification portion 8. The first member 4 includes, for example, 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.

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

The second member 6 is, for example, an electrical connection member such as a bus bar, and can electrically connect, for example, the first member 4 to another member. The second member 6 has, for example, a plate shape or a substantially plate shape. The second member 6 includes, for example, a metal such as the aluminum alloy or stainless steel described above. The second member 6 may be a metal such as the aluminum alloy or stainless steel described above. The second member 6 is, for example, a member that suppresses deformation due to creep. Creep is a phenomenon in which deformation of an object increases over time when a certain amount of stress is applied. In general, deformation due to creep of a member with high strength is small, and a member with high strength suppresses 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 with higher strength than the first member 4.

The second member 6 includes a fusion connection portion 12 and a fastening portion 14. The fusion connection portion 12 includes a second joint surface portion 16 for the weld solidification portion 8. The second joint surface portion 16 is arranged on a ring such as a circumference, and the end portion of the first member 4 is inserted into the inside of the second joint surface portion 16. The first joint surface portion 10 of the first member 4 is arranged on an extension of the second member 6 having a plate shape or a nearly plate shape. The fastening portion 14 includes, for example, a fastening hole 18, and can be fastened to another member by a fastening member such as a bolt or a screw. The second member 6 has a strength higher than the level at which the fastening member can be prevented from loosening, and prevents the fastening member from loosening.

The weld solidification portion 8 is disposed between the first joint surface portion 10 of the first member 4 and the second joint surface portion 16 of the second member 6, and is joined to the first joint surface portion 10 and the second joint surface portion 16 to form a butt joint. The weld solidification portion 8 is formed by solidification of the first member 4 and the second member 6 (hereinafter referred to as "members 4, 6") that are melted during welding, and is a mixed member of the members 4, 6. The weld solidification portion 8 has, for example, a semi-elliptical or approximately semi-elliptical cross-sectional shape. The weld solidification portion 8 includes a first solidification portion 20 and a second solidification portion 22. The weld solidification portion 8 has, for example, a ring shape at the exposed surface, as shown in A of FIG. 1.

The first solidified portion 20 is disposed outside the weld solidified portion 8, i.e., in the periphery of the weld. The first solidified portion 20 contacts and joins the first joining surface portion 10 and the second joining surface portion 16, connecting the first member 4 to the second member 6. For example, the members 4 and 6 melted by the first heating such as the first laser irradiation are cooled, and the first solidified portion 20 is formed. The members 4 and 6 are cooled, for example, by natural cooling, or may be lightly forced cooling.

The second solidified portion 22 is disposed inside the weld solidified portion 8, that is, at and near the weld center P of the weld. The weld center P is the elliptical center of the weld solidified portion 8, which has a semi-elliptical or nearly semi-elliptical cross-sectional shape, and coincides or nearly coincides with the heating point of the weld. For example, a part of the members 4, 6 that has been cooled after melting is remelted and recooled by a second heating such as a second laser irradiation to form the second solidified portion 22. The recooling after the second heating is, for example, natural cooling, or may be light forced cooling.

The weld solidification zone 8 has residual stress. Residual stress is stress that remains within an object after it has been subjected to an external force and the external force is removed. For example, residual stress occurs when an object that has been heated during heat treatment is cooled. Also, in heat treatment of dissimilar components, if the mixture of the dissimilar components is uneven, the composition of the material becomes uneven and residual stress occurs.

The heated weld is cooled from the periphery of the weld, and finally the center of the weld is solidified. Therefore, in general welding, residual stress (tensile stress) is high in the center of the weld. In addition, the residual stress increases as the amount of heat applied during welding increases and the volume of the melted material increases. However, in the weld 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 weld center P and in the vicinity of the weld center P is suppressed. If the second member 6 is made of a material different from the first member 4, remelting the members 4 and 6 promotes mixing of the members 4 and 6, and can suppress residual stress due to non-uniformity of the material. In other words, even if the second member 6 and the first member 4 are made of different materials, it is possible to suppress residual stress and maintain a stable connection structure.

The width W2 of the cross section of the second solidification portion 22 is, for example, 10% or more and 70% or less of the width W1 of the cross section of the weld solidification portion 8. If the second solidification portion 22 is approximately similar to the weld solidification portion 8, when the width W2 is 70% or less of the width W1, the cross section of the second solidification portion 22 is suppressed to half or less of the entire cross section of the weld solidification portion 8. From the area ratio, the second heat amount is 50% or less of the first heat amount applied to the members 4 and 6 by the first heating. The second heat amount is smaller than the first heat amount, and the residual stress of the second solidification portion 22 is suppressed. The residual stress of the weld center P of the weld solidification portion 8 and its vicinity can be suppressed more than the residual stress of the weld center P of the weld solidification portion consisting of only the first solidification portion 20 and its vicinity.

When width W2 is, for example, 10% or more of width W1, second solidification portion 22 is sufficiently positioned on the surface near the center where residual stress is high. In other words, second solidification portion 22 can make the center of the exposed surface, where cracking is likely to occur, less susceptible to cracking. If second solidification portion 22 is roughly similar to weld solidification portion 8, when width W2 is 10% or more of width W1, the cross-sectional area of second solidification portion 22 is 9% or more of the entire cross-sectional area of weld solidification portion 8. The second amount of heat is 9% or more of the first amount of heat based on the area ratio.

The weld center P is disposed, for example, on the first member 4 side with respect to the butt surface S of the members 4 and 6. The butt surface S is the surface formed by butting the members 4 and 6 before welding. When the weld center P is disposed on the first member 4 side, if 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 the laser is irradiated on the second member 6 with higher strength, and therefore residual stress can be suppressed. When the weld center P is disposed on the first member 4 side, if the second member 6 has a lower strength than the first member 4, the difference in the amount of melting of the members 4 and 6 can be reduced compared to when the laser is irradiated on the second member 6 with lower strength.

The weld center P may overlap the butt surface S, or may be positioned on the second member 6 side of the butt surface S. Welding in which the weld center P overlaps the butt surface S can reduce the difference in the amount of melting between the members 4 and 6.

Figure 3 shows an example of a welding method. The inverted triangle symbols shown in Figure 3B and Figure 3D represent the irradiation of laser light, and the arrows shown in Figure 3C represent the direction of residual stress, indicating that tensile stress exists in the weld solidification part 8 centered on the center of the weld solidification part 8. The welding method shown in Figure 3 is an example, and the technology of the present disclosure is not limited to such a method.

The second member 6 before welding includes, for example, a circular through hole that is slightly larger than the end of the first member 4 before welding. The second member 6 may have a plurality of such circular through holes. If the number of through holes is large, high precision is required for the arrangement of the end of the first member 4 and the through holes, and achieving high precision increases the manufacturing cost. However, by having the through hole have a diameter of about 0.1 to 0.5 mm larger than the end of the first member 4, a gap of about 0.1 to 0.5 mm is generated, so that the end of the first member 4 and the through hole can be arranged without requiring high precision. As shown in FIG. 3A, the end of the first member 4 is inserted, for example, into the through hole of the second member 6, and the first member 4 is adjacent to the second member 6.

As shown in FIG. 3B, adjacent portions 32 of adjacent members 4 and 6 are melted by a first heating such as a first laser irradiation to form a melted portion 34. In FIG. 3B, the center of the first heating is disposed on the first member 4 side with respect to the butt 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, a stable connection can be achieved. However, the center of the first heating may overlap the butt surface S, or may be disposed on the second member 6 side with respect to the butt surface S.

The first heating moves relative to the members 4 and 6, for example, circumferentially, to melt the adjacent portion 32, for example, in an annular shape. In the relative movement of the first heating, the laser irradiation device may move, or the members 4 and 6 may move. As the heated portion moves, the melted portion 34 is cooled, for example, naturally, and a solidified portion 36 is formed, as shown in C of FIG. 3.

As already mentioned, the heated weld is cooled from the periphery of the weld, and the center of the weld is finally solidified. Therefore, the residual stress in the solidified portion 36 is high in the center of the solidified portion 36, and is generated from the center of the solidified portion 36.

As shown in D of FIG. 3, a part of the solidified portion 36 is remelted by the second heating such as the second laser irradiation, and a remelted portion 38 is formed. The second heating is applied, for example, to the heating center in the first heating, that is, the width center of the solidified portion 36. The second heating may be applied to the first member 4 side or the second member 6 side with respect to the heating center in the first heating. The second amount of heat is controlled to be less than the first amount of heat, and the residual stress of the second solidified portion 22 (E in FIG. 3) formed by solidification of the remelted portion 38 can be made smaller than the residual stress of the solidified portion 36 before remelting. In other words, the residual stress can be released by remelting the solidified portion 36. The second amount of heat is adjusted, for example, to 9% or more and 50% or less of the first amount of heat, and the width W2 is adjusted to 10% or more and 70% or less of the width W1. The first amount of heat and the second amount of heat are adjusted, for example, by any 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, 6. Adjustment (3): Adjustment of the incidence angle of the first laser and the second laser with respect to the members 4, 6. Adjustment (4): Adjustment of the heating time of the first heating and the second heating. Adjustment (5): Adjustment of the relative moving speed of the first heating and the second heating with respect to the members 4, 6. Adjustment (6): Combination of multiple adjustments such as adjustments (1) to (5).

The second heating moves the solidification portion 36 relatively to the members 4 and 6, for example, circumferentially, and remelts the solidification portion 36, for example, annularly. As a result, the remelted portion 38 cools, and as shown in FIG. 3E, a weld solidification portion 8 including a first solidification portion 20 and a second solidification portion 22 is formed.

The welded structure 2 is manufactured, for example, by the welding method already described. The manufacturing method of the welded structure is similar to the welding method already described, for example, and the description thereof is omitted.

According to the embodiment, the following actions or effects can be obtained:

(1) Residual stress generated in a welded part can cause cracks in the welded part. It is believed that residual stress occurs due to the following factors, for example:
Cause (1): When laser welding dissimilar components, the molten components cool without being sufficiently mixed, resulting in differences in the rate of partial shrinkage.
Factor (2): In order to firmly connect the components, a high-power laser is irradiated to form a large weld with large distortion.
Factor (3): Metals that are prone to residual stress and have high cracking sensitivity, such as alloys containing magnesium, are used.
Factor (4): The weld is formed with a shape that increases residual stress. A weld with a curve, such as a ring shape, will have higher residual stress than a straight weld.
Factor (5): When a component is surface-treated, the material contained in the component surface precipitates during welding, causing a localized decrease in the component's strength.

Due to required performance or specifications, it may be difficult to eliminate factors (1) to (5) above. Welded structure 2 can suppress cracking even when factors (1) to (5) exist, and can also suppress cracking in the welding of components selected for required performance or specifications.

The welded structure 2 includes a second solidified portion 22 formed by a second amount of heat smaller than the first amount of heat, and this second solidified portion 22 has a cross-sectional area smaller than the cross-sectional area of the welded solidified portion 8 and has small residual stress. The formation of the second solidified portion 22 can release, cancel, or alleviate the residual stress. As a result, a welded structure 2 that is less likely to crack can be obtained.

(2) Because the welded structure 2 is less likely to crack, the freedom to combine components can be increased.

(3) Because the welded structure 2 is less likely to crack, it is possible to select materials to be used by prioritizing performance or specifications such as electrical properties, strength, hardness, and durability rather than weldability. In other words, it is possible to improve the performance or specifications of the welded structure 2.

Figure 4 shows an example of an electronic component according to the embodiment. Figure 5 shows an example of an end bus bar of an electronic component. The end bus bar 64 is, for example, symmetrical with respect to the line L shown in Figure 5A, and Figure 5A shows an end bus bar with some parts omitted. The configuration shown in Figures 4 and 5 is an example, and the technology of the present disclosure is not limited to such a configuration. In Figures 4 and 5, the same parts as in Figure 1 are given the same reference numerals. In this embodiment, the side on which the first holder 56 is installed is referred to as the upper side, and the side on which the second holder 58 is installed is referred to as the lower side.

The electronic component 52 is, for example, an energy storage device module, and includes a plurality of energy storage devices 54, a first holder 56, a second holder 58, a plurality of holder connection members 60, a connecting bus bar 62, an end bus bar 64, and a weld solidification portion 8.

The multiple power storage devices 54 are, for example, 18 power storage devices 54, and are arranged so that six power storage devices 54 are arranged in a straight line to form three rows. In other words, the multiple power storage devices 54 are arranged in six rows and three columns. The power storage devices 54 have a power storage function and are, for example, electrolytic capacitors or electric double layer capacitors. 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.

The electrode terminal 68 is an example of the first member, and is a metal member made of, for example, pure aluminum (alloy number: 1070), which has excellent workability, corrosion resistance, weldability, and the like. The electrode terminal 68 has excellent corrosion resistance, which suppresses chemical reactions with the electrolyte and suppresses the effects on electrical characteristics caused by chemical changes in the electrode terminal 68 and the electrolyte. In other words, pure aluminum is a suitable material for the electrode terminal 68. The alloy number is, for example, the alloy number shown in Japanese Industrial Standard JIS H4000:2014 "Aluminum and Aluminum Alloy Plate and Strip."

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

The second holder 58 is disposed below the power storage device 54. The lower portion 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 containing, for example, a thermoplastic resin.

The holder connection member 60 is connected to the first holder 56 and the second holder 58, and maintains the 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 placed within this frame. The holder connection member 60 in the center maintains the distance between the first holder 56 and the second holder 58 at a set distance in the middle of the frame. The holder connection member 60 is, for example, a resin member containing a thermoplastic resin.

The connecting bus bar 62 is an example of an electrical connection member, and has, for example, a long and narrow plate shape, and is arranged on the first holder 56 so as to cross the three rows of the power storage devices 54. The connecting bus bar 62 is, for example, welded to adjacent electrode terminals 68 in each row, and electrically connects adjacent power storage devices 54 in each row. The connecting bus bar 62 also connects the welded electrode terminals 68 to the welded electrode terminals 68 in the other rows, and electrically connects, for example, six power storage devices 54. The connecting bus bar 62 is, for example, a member similar to the electrode terminals 68.

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 approximately plate shape, and is arranged on the first holder 56 so as to cross the three rows of the power storage devices 54. The end bus bar 64 is welded to the end electrode terminals 68 in each row. The end bus bar 64 also connects the welded electrode terminals 68 to the welded electrode terminals 68 in the other rows, and electrically connects, for example, three power storage devices 54.

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) is readily available and is cost-effective. When the end bus bar 64 is fastened to another member with fastening members such as bolts and screws, the end bus bar 64, which has high strength, can suppress loosening of the fastening members.

The end bus bar 64 includes three fusion connections 12 and a fastening portion 70. The fusion connections 12 include 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 inside 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 a nearly plate shape. The weld 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 is joined to the first joint surface portion 10 and the second joint surface portion 16 to form a butt joint. The weld solidification portion 8 is similar to the weld solidification portion 8 described in the embodiment, and its description is omitted. The electrode terminal 68, the end bus bar 64, and the weld solidification portion 8 form a welded structure 72, and the electronic component 52 includes the welded structure 72.

The fastening portion 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 to 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 to fix 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 fixing tool 76 for positioning. If the end bus bar 64 is fixed to the first holder 56 by the fixing holes 74 and the fixing tool 76 after welding, there is a possibility that stress will be applied to the weld solidification portion 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 portion 8 during fixing.

The end busbar 64 may include other holes, steps, etc., as shown in FIG. 5, depending on the purpose.

The electronic components 52 may include additional circuits such as a balancing circuit, a temperature detection circuit, and a voltage detection circuit (not shown). The additional circuits are connected to the connecting busbar 62 or the end busbar 64, for example. A butt joint using the weld solidification portion 8 may be used to connect the additional circuits to the busbars.

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

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

In the welding process, the end busbar 64 is welded to the electrode terminal 68, for example, by the welding method described in the embodiment. The connecting busbar 62 is welded to the electrode terminal 68. To form the weld solidification portion 8 described above, the connecting busbar 62 may be welded to the electrode terminal 68, for example, by the welding method described in the embodiment. The explanation of the welding method described in the embodiment is omitted.

The electronic components according to the embodiments provide the following actions or effects:

(1) The action or effect described in the embodiment can be obtained.

(2) Even if the end bus bar 64, which has high strength and hardness, is welded to the electrode terminal 68, cracking of the weld solidification portion 8 can be suppressed.

(3) By preventing cracks, increases in electrical resistance and heat generation during electrical current can be suppressed.

(4) The electrical stability of the electronic component 52 can be improved.

(5) The end bus bar 64 has high strength and hardness, which can prevent loosening of the fastening member with other components. In other words, the thickness of the end bus bar 64 is maintained in a high-temperature environment or over time, so the axial force of the fastening member is maintained and loosening of the fastening member is prevented. Therefore, an increase in electrical resistance is prevented.

Features and variations of the embodiments or examples are listed below.

(1) In the above embodiment and example, the weld solidification portion 8 has a ring shape on the exposed surface. However, the shape of the weld solidification portion 8 is not limited to a ring shape. For example, the second member 6 or the end bus bar 64 may have an arc-shaped recess at the end, and this recess may be abutted against the end side of the first member 4 or the electrode terminal 68 to form the arc-shaped weld solidification portion 8. The shape of the upper part of the first member 4 or the electrode terminal 68 may be a shape other than circular, and the weld solidification portion 8 may have a shape corresponding to the shape of the first member 4 or the electrode terminal 68.

(2) In the above embodiment, the second member 6 includes the fastening portion 14, and in the above example, the end bus bar 64 includes the fastening portion 70. However, the second member 6 does not have to include the fastening portion 14, and the end bus bar 64 does not have to 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 the loosening of the fastening, such as rigidity or scratch resistance.

(3) In the above embodiment, the fastening portion 14 of the second member 6 includes a 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 be fastened to another member by the fastening member 118. As in the embodiment, the fastening portion 70 of the end bus bar 64 may include a fastening member 118 and be fastened to another member by the fastening member 118.

(4) In the welding method of the above embodiment and example, the solidified portion 36 is remelted to form the second solidified portion 22. The welding method is not limited to the welding method of the embodiment and example. For example, as shown in C of FIG. 7, the second heating may reheat a part of the molten portion 34 during the cooling 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 light forced cooling. Reheating a part of the molten portion 34 can slow the cooling rate of the other parts of the molten portion 34, and the residual stress of the first solidified portion 20 can be suppressed.

(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 pure aluminum (alloy number: 1070) described above, and may be a metal member made of other pure aluminum having a purity of, for example, 99% or more. The end bus bar 64 only needs to have a strength high enough to suppress loosening of the fastening member, and may be a metal member made of an aluminum alloy that can suppress loosening of the fastening member, for example, selected from aluminum alloys from 2000 series materials to 7000 series materials.

(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. In addition, 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 balancing circuit.

As described above, the most preferred embodiment of the present disclosure has been described. The present disclosure is not limited to the above description, and various modifications and changes are possible for those skilled in the art based on the gist of the invention described in the claims or disclosed in the specification. It goes without saying that such modifications and changes are included in the scope of the present disclosure.

The technology disclosed herein is useful not only for welding electronic components such as power storage device modules and circuits but also for welding a variety of other members.

Reference Signs List 2, 72 Welded structure 4 First member 6 Second member 8 Weld solidification portion 10 First joint surface portion 12 Melted connection portion 14, 70 Fastening portion 16 Second joint surface portion 18 Fastening hole 20 First solidification portion 22 Second solidification portion 32 Adjacent portion 34 Melted portion 36 Solidification portion 38 Remelted portion 52 Electronic component 54 Electricity storage device 56 First holder 58 Second holder 60 Holder connecting member 62 Connecting bus bar 64 End bus bar 66 Main body portion 68 Electrode terminal 74 Fixing hole 76 Fixing tool 118 Fastening member 138 Reheating portion

Claims (12)

A first member having a first bonding surface portion;
a second member having a second bonding surface;
a weld solidification portion formed by welding on the joint surface portion of the first member and the second member that are butted together;
Equipped with
A welded structure, characterized in that the weld solidification portion includes a first solidification portion and a second solidification portion formed inside the first solidification portion by remelting the first solidification portion. The second member has a strength greater than that of the first member,
2. The welded structure according to claim 1, wherein a weld center portion of the weld solidification portion is disposed on the first member side with respect to an abutment surface between the first member and the second member. The welded structure according to claim 1 or 2, characterized in that the second member further includes a fastening portion capable of being fastened to another member. The welded structure according to any one of claims 1 to 3, characterized in that the cross-sectional width of the second solidification portion is 10% or more and 70% or less of the cross-sectional width of the weld solidification portion. The welded structure according to any one of claims 1 to 4, characterized in that the weld solidification portion has a ring shape. An electronic component module having a welding structure according to any one of claims 1 to 5. a step of melting adjacent portions 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 a step of remelting or reheating a portion of the molten zone by a second heating to form a weld solidification zone including a first solidification zone and a second solidification zone formed inside the first solidification zone by remelting or reheating the first solidification zone. The second member has a strength greater than that of the first member,
The welding method according to claim 7, wherein the first heat is applied to a side of the first member with respect to a butt surface between the first member and the second member. The welding method according to claim 7 or 8, further comprising a step of forming a fastening portion in the second member that can be fastened to another member. The welding method according to any one of claims 7 to 9, characterized in that 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. the first heat and the second heat are applied circumferentially;
The welding method according to any one of claims 7 to 10, wherein the weld solidification zone has an annular shape. the first member is a terminal of an electronic component or a conductive member connectable to an electronic component;
12. The welding method according to claim 7, wherein the second member is an electrical connection member capable of electrically connecting the first member to another member.

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