JP2014187016A - Terminal manufacturing method, terminal, electric wire end connection structure manufacturing method, and electric wire end connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal that can be obtained by laser welding at heightened laser beam absorbing efficiency, and can shield an electric wire conductor from an environment without enlarging a crimp part of the terminal, a terminal and electric wire end connection structure manufacturing method, and an electric wire end connection structure.SOLUTION: A method of manufacturing a terminal 1 having a tubular caulking part 30 crimped and jointed to an electric wire sequentially has steps of: forming a high melting point metal layer made of high melting point metal selected from any one kind of ruthenium, rhodium, palladium, osmium and iridium on a plate material made of copper or a copper alloy at a portion at which at least the tubular caulking part is formed with thickness of 0.05 μm to 1.2 μm; forming a tin layer thereon; forming a terminal substrate by punching the plate material into a development elevation view of the terminal; bending a tubular development part of the tubular caulking part; abutting opposed ends of the tubular development part against each other; jointing 50 an abutting part by laser welding; and forming the tubular caulking part 30.

Description

  The present invention relates to a method for manufacturing a terminal excellent in laser weldability, a terminal, a method for manufacturing a terminal connection structure for electric wires, and a terminal connection structure for electric wires.

  In recent years, there has been a demand for weight reduction of each component in order to improve the fuel efficiency of automobiles. Therefore, replacing the core wire of the electric wire used for the wire harness etc. in a motor vehicle with aluminum or aluminum alloy lighter than copper or copper alloy is advanced. Since a metal material is usually used for a terminal to be crimped and connected to the tip of this aluminum electric wire or aluminum alloy electric wire (hereinafter simply referred to as “aluminum electric wire”), these terminals are appropriately connected at the terminal connection portion of the electric wire. It will be necessary.

In general, the terminal is made of copper or a copper alloy from the viewpoint of mechanical strength and springiness. Since the aluminum or aluminum alloy of the wire conductor is exposed at the crimping part of the terminal, if moisture adheres to the connection part of the aluminum wire and the terminal, the aluminum or aluminum alloy of the aluminum wire and the copper or copper alloy of the terminal Since the potential difference is different between different metals, corrosion (electrocorrosion) may occur, and defects may occur when corrosion progresses. Further, due to the progress of corrosion, the connection portion between the electric wire and the terminal is cracked or has poor contact, and the product life has been shortened.
In order to prevent these problems, it is desirable to block aluminum or an aluminum conductor (hereinafter simply referred to as “aluminum conductor”) from the outside. As an example, there is a method (for example, see Patent Document 1) in which the entire crimped portion of the terminal is molded with resin, and corrosion can be reliably prevented. Moreover, the technique (for example, refer patent document 2) which interrupts | blocks an aluminum conductor from the external world by the method of crimping | bonding after covering a metal cap on an electric wire conductor is disclosed.

On the other hand, the applicant of the present application forms a tubular crimped portion of a terminal by butt welding both ends of a terminal base material stamped and formed from a copper alloy plate material by laser welding, and an aluminum conductor of an aluminum electric wire in the tubular crimped portion. The conductor is accommodated in a copper alloy terminal by being caulked after being inserted, and is electrically connected, and the connection part between the conductor which is a dissimilar metal joint and the tubular caulking part does not come into contact with external moisture It is proposed that
However, when laser welding copper or copper alloy, copper or copper alloy has a high reflectivity of 90% or more of near-infrared laser light widely used as laser light for welding (absorbability of laser light). Therefore, the efficiency of laser welding is poor and the welding speed cannot be increased (see, for example, Patent Document 3).

JP 2011-222243 A JP 2004-207172 A JP 2011-1117048 A

In the technique described in Patent Document 1, since the mold portion is enlarged, it is necessary to increase the size of the connector housing, and as a result, the connector is enlarged. For this reason, the entire assembled electric wire (for example, a wire harness for automobiles) using this connector cannot be molded in a high density and small size. Moreover, it is necessary to process each crimping | compression-bonding part after a crimping | compression-bonding, the number of processes of manufacturing an assembled electric wire increases greatly, and each operation | work is complicated.
Moreover, in the technique described in Patent Document 2, the process of attaching the tube body to each conductor before crimping is complicated, and the tube body is destroyed by the wire barrel at the time of crimping, resulting in a flooded path. There was a fear.
Therefore, when a copper or copper alloy plate material for forming a terminal is formed into a tubular body by butt welding, the reflectance of the laser beam is lowered with respect to the copper or copper alloy plate material, particularly in the tubular body forming portion ( There has been a demand for a method for efficiently forming a tubular structure of a terminal by laser welding, which is a simple welding method, by performing a process that improves the absorption of laser light.

  The present invention provides a method of manufacturing a terminal, a terminal, and an end connection structure of a wire, which is obtained by laser welding with improved laser light absorption efficiency and can shut off a wire conductor from the outside without enlarging a crimping portion. It is an object of the present invention to provide a manufacturing method and an end connection structure for electric wires.

  As a result of intensive studies to solve the above problems, the present inventors have adopted a structure in which an electric wire is inserted into and crimped to a terminal of a tubular body, thereby making it possible to connect the electric wire conductor to the outside world without enlarging the crimping portion. In addition, the present inventors have found a laser welding method in which laser welding is improved by laser welding a copper alloy from the viewpoint of processing speed and cost and providing a predetermined layer on the surface of the copper alloy. The present invention has been made based on these findings.

That is, the said subject is solved by the following means.
(1) A method for producing a terminal having a tubular caulking portion that is crimp-bonded to an electric wire,
A refractory metal layer made of a refractory metal selected from any one of ruthenium, rhodium, palladium, osmium, iridium and platinum on at least a portion forming the tubular caulking portion with respect to a plate made of copper or a copper alloy Is formed with a thickness of 0.05 μm to 1.2 μm,
Forming a tin layer on the refractory metal layer;
Forming the terminal base material by punching out the plate material in which the refractory metal layer and the tin layer are formed in a developed view of the terminal,
Bending a tube expanding portion that becomes a portion forming the tubular caulking portion of the terminal base material, but facing opposite ends of the tube expanding portion to form a butted portion;
The manufacturing method of the terminal which has each process which joins the said butt | matching part by laser welding and forms the said tubular crimping part in this order.
(2) A method for producing a terminal having a tubular caulking portion that is crimp-bonded to an electric wire,
A terminal base material is formed by punching a plate made of copper or a copper alloy into a developed view of the terminal,
A refractory metal layer made of a refractory metal selected from any one of ruthenium, rhodium, palladium, osmium, iridium, and platinum is formed on the tube development portion that forms the tubular caulking portion of the terminal base material. .05 μm to 1.2 μm thick,
Forming a tin layer on the refractory metal layer;
Bending the pipe expanding portion, butting the opposite ends of the pipe expanding portion together to form a butt portion;
The manufacturing method of the terminal which has each process which joins the said butt | matching part by laser welding and forms the said tubular crimping part in this order.
(3) The method for manufacturing a terminal according to (1) or (2), further including a step of forming a tip sealing portion by closing an end portion of the tubular caulking portion on the transition portion side by laser welding.
(4) The method for manufacturing a terminal according to any one of (1) to (3), wherein the refractory metal layer is formed by plating.
(5) The refractory metal layer is formed on the surface of the tube development portion on the laser welded side, and then the tin layer is formed thereon. (1) to (4) Terminal manufacturing method.
(6) The terminal according to any one of (1) to (5), wherein the refractory metal layer is formed in the laser-welded region of the tube development portion, and then the tin layer is formed thereon. Manufacturing method.
(7) The terminal according to any one of (1) to (6), wherein the refractory metal layer is formed on the opposing end portion of the tube development portion, and then the tin layer is formed thereon. Manufacturing method.
(8) The method for manufacturing a terminal according to any one of (1) to (7), wherein the laser welding uses laser light having an oscillation wavelength in a near infrared region.

(9) A terminal having a tubular caulking portion that is crimp-bonded to an electric wire,
The terminal base material forming the terminal is made of copper or a copper alloy,
The tubular caulking portion is formed by bending a tube expanding portion of the terminal base material and abutting the opposite end portions thereof, and the abutting portion is joined by laser welding,
A refractory metal layer made of a refractory metal selected from any one of ruthenium, rhodium, palladium, osmium, iridium, and platinum is 0.05 μm to 1.2 μm in thickness on the laser-welded terminal base material. Formed,
A tin layer is formed on the refractory metal layer,
Terminals that prevent diffusion of the terminal base material and tin in areas other than those melted by laser welding.

(10) A terminal connection structure for an electric wire, in which the terminal produced by the method for producing a terminal according to any one of (1) to (8) and a covered electric wire are connected by crimping at a tubular caulked portion of the terminal. A manufacturing method of
Insert the covered electric wire with the core wire exposed from the end into the tubular caulking portion,
A method for manufacturing an end connection structure for electric wires, wherein the tubular caulking portion is caulked and the covered electric wire is crimped and connected to the tubular caulking portion.
(11) A terminal connection structure for electric wires in which the terminal according to (9) and a covered electric wire are connected by crimping at a tubular caulking portion of the terminal.

According to the method of manufacturing a terminal of the present invention,
(1) It is possible to perform joining by butt welding between copper alloys by high-speed welding, and the caulking portion can be formed into a tubular shape at a low cost,
(2) In crimping connection of aluminum wires, etc., it is possible to provide a terminal that contributes to prevention of corrosion between different metals between the base material of the terminal and the metal material of the wire without enlarging the crimping part,
(3) By forming a tin layer on the surface of the copper alloy, it is possible to increase the absorption of near-infrared laser light, and to make it difficult to generate blowholes, which is an evaluation of weldability.
(4) Since a tin layer having a low melting point and easy to absorb laser light is formed on the outermost surface, the laser beam is directly irradiated to the terminal base material of copper or copper alloy, and laser welding is performed. Even if the laser beam irradiation energy is lowered, the tin layer melts immediately, so laser welding with low energy is possible,
(5) Since a refractory metal layer is formed as a base layer between the copper or copper alloy terminal base material and the outermost tin layer, the refractory metal layer serves as a diffusion barrier layer in the terminal base material. It is possible to prevent the contact resistance from increasing due to the difficulty of diffusion of copper into the tin layer side. Further, the ability to keep the contact resistance low in this way is advantageous, for example, when caulking between the obtained terminal and the electric wire conductor.

It is the perspective view which showed one preferable embodiment of the terminal of this invention. It is sectional drawing which showed the longitudinal direction cross section of the tubular crimping part of the terminal which concerns on this invention. It is the perspective view which showed another preferable aspect of the terminal of this invention. It is the perspective view which showed another preferable aspect of the terminal of this invention. It is the perspective view which showed the termination | terminus connection structure of the electric wire formed using the terminal of this invention. It is the perspective view which showed typically one state during manufacture of the terminal of this invention. It is the top view which showed the state which the terminal base material before shaping | molding of the female terminal produced by stamping and pressing a board | plate material was expand | deployed. It is the perspective view which showed the state which processed the terminal base material and shape | molded in the tubular crimping part.

  A preferred embodiment of the present invention will be described with reference to the drawings. The embodiment shown below is an example, and various embodiments can be taken within the scope of the present invention.

  FIG. 1 shows a terminal 1 which is a preferred embodiment of a terminal manufactured by the manufacturing method of the present invention. The terminal 1 connects the electric wire and the base material of the terminal 1 (hereinafter also referred to as a terminal base material) by crimping after the box portion 20 of the female terminal and a covered electric wire (for example, an aluminum electric wire) are inserted. A tubular caulking portion 30 is provided, and a transition portion 40 that connects the box portion 20 and the tubular caulking portion 30 is provided. Further, the terminal 1 has a laser welding portion 50 (first laser welding portion) in the tubular caulking portion 30, and a tip sealing portion 52 (second laser) closed by laser welding on the transition caking portion 40 side of the tubular caulking portion 30. Welded part). The terminal 1 is basically made of a terminal base material made of a metal material (copper alloy or the like) in order to ensure conductivity and strength. The shape of the laser weld 50 is not particularly limited. It is preferable to form in a band shape in the longitudinal direction of the tubular caulking portion 30 like the laser welding portion 50. Furthermore, the welding shape of the tip sealing portion 52 is not particularly limited.

  The terminal base material constituting the terminal 1 is preferably made of a copper alloy. The thickness of the terminal substrate is preferably 0.08 to 0.64 mm. When the wire diameter is small in an automobile terminal, a thickness of 0.25 mm is often used. Moreover, copper (tough pitch copper, oxygen-free copper, etc.) can also be used as a material for the terminal base material instead of the copper alloy. Examples of the copper alloy used for the terminal base material include brass (for example, C2600 and C2680 of CDA (Copper Development Association)), phosphor bronze (for example, C5210 of CDA), and Corson type copper alloy (Cu—Ni—Si—). (Sn, Zn, Mg, Cr) -based copper alloy) and the like, and among them, a Corson copper alloy is preferable.

Examples of the Corson copper alloy include, but are not limited to, copper alloys FAS-680 and FAS-820 (both trade names) manufactured by Furukawa Electric Co., Ltd., and copper alloys MAX- manufactured by Mitsubishi Shindoh. 375, MAX251 (both are trade names) can be used. Also, CDA C7025 or the like can be used.
An example of the alloy composition of the FAS-680 is 0.15% by mass of tin (Sn), 0.5% by mass of zinc (Zn), 2.3% by mass of nickel (Ni), and 0 of silicon (Si). .55% by mass and 0.1% by mass of magnesium (Mg), with the balance being copper (Cu) and inevitable impurities.
An example of the alloy composition of FAS-820 is as follows: tin (Sn) 0.15 mass%, zinc (Zn) 0.5 mass%, nickel (Ni) 2.3 mass%, silicon (Si) 0.65 mass%, magnesium (Mg) 0.1 mass%, and chromium (Cr) 0.15 mass%, with the balance being copper (Cu) and inevitable impurities.

Examples of other copper alloy compositions include, for example, Cu—Sn—Cr based copper alloys, Cu—Sn—Zn—Cr based copper alloys, Cu—Sn—P based copper alloys, Cu—Sn—P—Ni. Examples thereof include a copper alloy, a Cu—Fe—Sn—P copper alloy, a Cu—Mg—P copper alloy, and a Cu—Fe—Zn—P copper alloy.
Here, it is natural that inevitable impurities may be included in addition to the essential elements described above.

  The terminal base material is made of a high melting point metal selected from any one of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt). A melting point metal layer (not shown) is formed. Further, a tin (hereinafter also referred to as Sn) layer (not shown) is formed on the refractory metal layer as the outermost layer of the terminal 1. The thickness of the refractory metal layer is 0.05 μm to 1.2 μm, preferably 0.5 to 1.0 μm. If the refractory metal layer is too thick, the amount of energy required to dissolve the plating layer itself will increase too much, resulting in poor weldability. If it is too thin, the effect as a diffusion barrier layer cannot be obtained. In addition, you may provide a metal layer between a terminal base material and a refractory metal layer as needed. This metal layer is provided in order to improve the adhesion between the terminal base material and the refractory metal layer and to prevent the mutual diffusion of the components. This metal layer is preferably made of copper (Cu), nickel (Ni), cobalt (Co) or an alloy thereof. The metal layer may be composed of a plurality of layers.

Moreover, although the thickness of Sn layer is not specifically limited, Usually, it is about 0.3-1.2 micrometers. When Sn plating is thin, copper easily diffuses to the tin layer side by heat, but by taking this configuration having a refractory metal layer below the tin layer, diffusion of copper to the tin layer side can be prevented. . Therefore, it is possible to prevent an increase in contact resistance.
Further, since the Sn layer is formed on the outermost layer, the absorption of near-infrared laser light is enhanced more than the surface of copper or copper alloy. For this reason, since the absorption efficiency of laser energy becomes higher than direct irradiation of near infrared laser light to copper or copper alloy of the terminal base material, the welding speed can be increased.

In the laser welding part 50, the whole including a refractory metal basically melts. Therefore, it mixes in a fusion | melting part, and a Cu-Sn-M alloy (however, M is a refractory metal) is produced | generated.
However, the refractory metal layer is diffused between Cu in the copper alloy of the terminal base material and Sn in the Sn layer including the heat affected zone (Heat Affected Zone, HAZ) in a portion other than the laser weld 50. prevent.

The manufacturing method of the refractory metal layer preferably uses a plating treatment in terms of cost. As the plating method, electroplating, electroless plating and the like are possible. If possible, various film forming techniques such as vapor deposition, ion plating, sputtering, and chemical vapor deposition can also be employed.
When forming the refractory metal layer by plating, conventional pretreatment means such as cathode electrolytic degreasing in an aqueous solution of sodium hydroxide, pickling treatment by dipping in diluted sulfuric acid, activation treatment, etc. A plating film excellent in adhesion can be formed.

  The box part 20 of the female terminal is a box part that allows insertion of an insertion tab such as a male terminal. In the present invention, the detailed shape of the box portion is not particularly limited. That is, in another embodiment of the terminal of the present invention, the box portion may not be provided. For example, an insertion tab of a male terminal may be used instead of the box portion. Moreover, the edge part of the terminal which concerns on another form may be sufficient. Here, in order to explain the terminal of the present invention, an example of a female terminal is shown for convenience. Any terminal having any connecting end may have the tubular caulking portion 30 via the transition portion 40. Moreover, it is preferable that the laser welding part 50 formed in the tubular crimping part 30 is softer than the terminal base material which comprises a tubular crimping part.

The tubular caulking part 30 is a part that crimps and joins the terminal 1 and an electric wire (not shown). One end has an insertion port 31 into which an electric wire such as an aluminum electric wire or its conductor can be inserted, and the other end is connected to the transition portion 40. The tubular caulking portion 30 is formed on the transition portion 40 side by crushing two opposing pipe walls (usually upper and lower pipe walls) of the tubular caulking portion 30 by crushing such as pressing, for example, laser welding or the like. It has the structure of a “can body” that is closed by the welding process and opens at the insertion opening 31 of the electric wire or conductor with the closed portion as the bottom. The transition part 40 side of the tubular caulking part 30 is closed. When moisture adheres to the contact between the terminal base material (copper alloy or the like) of the terminal 1 and the aluminum electric wire, either metal (alloy) corrodes due to the difference in electromotive force between the two metals. The tube is closed at one end so that moisture and the like do not enter from the outside. If the crimping portion of the terminal of the present invention is a tubular body, a certain effect against corrosion can be obtained. Therefore, the crimped portion does not necessarily have to be a cylinder in the longitudinal direction. It may be. Further, the diameter does not need to be constant, and the radius may change in the longitudinal direction.
When this terminal 1 is used, the tubular caulking portion 30 is a tubular body whose one end is closed, so that it is difficult for moisture from the outside to adhere to the contact between the aluminum electric wire and the terminal base material of the terminal 1.

  In the tubular caulking portion 30, the terminal base material and the aluminum (aluminum alloy) electric wire constituting the tubular caulking portion are mechanically pressure-bonded to each other, thereby simultaneously ensuring electrical joining. The caulking is performed by plastic deformation of a terminal base material or an electric wire (core wire). Accordingly, the tubular caulking portion 30 needs to be designed to have a thickness so that it can be caulked and joined, but since it can be joined freely by manual machining or machining, it is particularly limited. is not.

The tubular caulking portion 30 of the present invention is configured by abutting plate terminal base materials, and has a laser welded portion 50 that joins the butted portions. That is, the laser welded portion 50 is continuously provided in the longitudinal direction along the butted portion of the tubular caulking portion 30. And it is provided as a linear area | region from the transition part 40 to the insertion port 31. FIG.
Further, the laser welded portion 50 is formed by forming a Sn layer on the surface of the terminal base material and a refractory metal layer therebelow before the laser welding. Absorption can be increased.
After laser welding, the laser weld 50 is melted to obtain a re-solidified structure. However, around the laser weld 50, the Sn layer has copper (Cu) in the terminal base material due to the effect of the refractory metal layer. A pure Sn layer remains on the surface layer without diffusion.

  A part of a longitudinal sectional view of the tubular caulking portion 30 is shown in FIG. In this figure, the description of the laser welded portion (ie, laser welded portion) 50 is omitted. As described above, the tubular caulking portion 30 is constituted by the terminal base material 32 made of a copper alloy. Further, the inner wall surface 33 of the tubular caulking portion may have an electric wire locking groove 34a or 34b for maintaining a contact pressure with the electric wire. Aluminum and aluminum alloy, which are the core wires of electric wires, have an oxide film having higher insulating properties than the copper oxide film on the surface, and therefore there is anxiety in connection as compared with the copper alloy. Therefore, by providing such a groove, the contact pressure is increased by the crest of the groove. In FIG. 2, the wire locking groove 34a is a groove having a rectangular cross section, and the wire locking groove 34b is a groove having a semicircular cross section. Such a wire locking groove can be easily provided if the terminal base material itself is processed before the tubular caulking portion 30 is formed. It can be provided by fiber laser processing, which will be described later, or cutting by a machine. In addition, if such an electric wire latching groove is provided in advance before the tubular caulking portion 30 is formed, efficient production can be achieved.

In addition, since an aluminum electric wire or its conductor is inserted in the tubular crimping part from the insertion port 31, it is preferable that the electric wire latching grooves 34a and 34b are provided in the position which contacts an aluminum core wire. An aluminum electric wire is usually composed of an aluminum core wire (conductor) and an insulating coating covering the same. The electrical connection between the electric wire and the terminal is performed by crimping and joining the aluminum core wire from which the insulating coating at the tip is removed (peeled) to the tubular caulking portion of the terminal. Therefore, ensuring sufficient contact pressure leads to maintenance of electrical performance, so that a groove such as a wire locking groove is required. Such grooves are also called serrations.
Then, by providing at least one or more wire locking grooves on the inner surface of the tubular caulking portion 30, the terminal and the wire are securely bonded to each other, so that the long-term reliability can be improved.

  As mentioned above, although the terminal of this invention has been demonstrated based on the aspect shown in FIG. 1, the aspect of the terminal of this invention is not limited to this.

  For example, as shown in FIG. 3, a stepped tube body in which the tubular caulking portion of the terminal 100 is composed of a plurality of tube bodies having different inner diameters before being crimped to the electric wire may be used. Specifically, the step tubular caulking portion 80 has a laser welded portion 500 similar to the above-described tubular caulking portion 30 (see FIG. 1), and the transition portion 40 side is closed by a tip sealing portion 502 by welding. A crimping portion 82 that is a member and is crimped to an insulation coating of a wire (not shown), a reduced diameter portion 83 that is reduced in diameter from the insertion port 81 side toward the transition portion 40 side, and a conductor of the wire. You may have the conductor crimping | compression-bonding part 84 and the diameter reducing part 85 which further reduces in diameter toward the transition part 40 side from the insertion port 81 side, and the edge part is obstruct | occluded by welding. In FIG. 3, there are two types of tubular portions (covered crimping portion 82 and conductor crimping portion 84), but three or more types may be used in accordance with the application and design.

  Since the tubular caulking portion 80 has a stepped shape in this way, when the end portion of the wire is removed and the end portion is inserted into the stepped tubular caulking portion 80, the insulation coating of the electric wire is reduced in diameter 83. As a result, the insulation coating is positioned directly below the covering crimping portion 82, and the electric wire conductor is positioned directly below the conductor crimping portion 84. Therefore, the end of the electric wire can be easily positioned, the crimping between the cover crimping portion 82 and the insulating coating, and the crimping between the conductor crimping portion 84 and the conductor can be performed reliably, and good water stopping and electrical It is possible to achieve excellent adhesiveness while achieving simultaneous connection.

  1 shows an example of a female terminal having the box portion 20, but the present invention is not limited to this, and the connection portion with another terminal may be the male terminal 101. Specifically, as shown in FIG. 4, an insertion port 91 for inserting an unillustrated electric wire, a tubular caulking portion 90 to be crimped to the electric wire, a tubular caulking portion 90, and the transition portion 40 are integrally formed. It may be a terminal provided with a male connection portion 21 provided and electrically connected to an external terminal (not shown). The tubular caulking portion 90 has a laser welded portion 501 and a tip sealing portion 503 in the same manner as the tubular caulking portion 30 described above. The male connecting portion 21 has a long insertion tab 21a, and a female terminal (not shown) having the insertion tab 21a as an external terminal (for example, a terminal having a box portion 20 as shown in FIG. 1). ) Is inserted along the longitudinal direction to be electrically connected. Further, a terminal having a male connecting portion 21 at the front end and a stepped caulking portion as shown in FIG. 3 at the rear end is also permitted.

FIG. 5 shows an example of the end connection structure 10 for electric wires according to the present invention. The terminal connection structure 10 of this example has a structure in which the stepped terminal 100 of the present invention shown in FIG. 3 is connected to an aluminum electric wire (60). In the terminal connection structure 10, the terminal 100 and the electric wire 60 are crimped and joined by a tubular caulking portion 80. Although the manner of pressure bonding is not particularly limited, in FIG. 5, it is composed of a covering pressure bonding portion 82 and a conductor pressure bonding portion 84. Usually, when crimped and joined, the tubular caulked portion 80 undergoes plastic deformation and is crimped to the electric wire 60 by being reduced in diameter than the original diameter. At the time of pressure bonding, it is preferable that the conductor pressure bonding portion 84 is strongly pressure-bonded so as to be recessed inside the tubular caulking portion 80 to be a strongly pressure-bonded pressure bonding portion. In this case, a concave portion (not shown) may be formed in the conductor crimping portion 84. The crimp bonding may be performed with a reduced diameter of two stages or three or more stages.
In addition, the terminal connection structure (10) of the electric wire of the present invention is configured by using the stepped terminal (100) shown in FIG. 5 as the terminal of the present invention, and the terminal (1) shown in FIG. Alternatively, the terminal (101) shown in FIG. 4 may be used.

  In addition, the electric wire 60 consists of the insulation coating 61 and the core wire of the electric wire which is not shown in figure. Although the electric wire 60 may be a bare wire, from the viewpoint of corrosion prevention, an electric wire with an insulation coating is usually used. An arbitrary metal material can be used for the core wire of the electric wire, for example, copper or a copper alloy, or aluminum or an aluminum alloy. As described in the background section of this document, in recent years, an aluminum or aluminum alloy core wire has been used for weight reduction. However, the core wire (conductor) of the electric wire 60 used in the present invention is not limited to aluminum or aluminum alloy. This is because the waterproofness of the connecting portion between the core wire and the terminal of the electric wire can be cited as a problem to be solved by the present invention regardless of the combination of any kind of metal or alloy.

The electric wire terminal connection structure of the present invention contributes to the prevention of corrosion between different metals between an electric wire made of an aluminum material and a terminal base material made of a copper material. Further, since the laser welded portion 50 and the surrounding heat-affected zone can be an annealed portion that is softer than the terminal base material 32, it is possible to prevent a springback of the crimping portion between the electric wire and the terminal. Excellent long-term reliability.
The spring back is a phenomenon in which the processed part attempts to return to its original shape. That is, the deformed portion of the tubular caulking portion that is crimp-bonded to the electric wire (not shown) tries to return to the original shape by an elastic force or the like, so that a gap is formed between the inner surface of the tubular caulking portion 30 and the electric wire. . If such a springback occurs at the crimping portion of the terminal, not only will the contact failure between the electric wire 60 and the terminal 1 be caused, but also water may easily enter the gap and cause corrosion.

  When manufacturing the terminal connection structure 10 of the electric wire of the present invention, it is preferable to perform crimp bonding in which the laser welding portion 50 of the tubular caulking portion 30 is positively plastically deformed. When crimping the tubular caulking portion 30 of the terminal 1 and the electric wire 60, it is performed with a dedicated jig or a press machine. At this time, the entire diameter of the tubular caulking portion 30 may be reduced, but the tubular caulking portion may be partly strongly processed and crimped like a concave shape. At this time, the position may be adjusted so that the amount of plastic deformation of the laser weld 50 is increased. That is, when the adjustment is performed so that the tip of the convex portion at the time of press working is directly above (outside) of the laser weld 50, the amount of deformation of the laser weld 50 increases. If it does in this way, since the comparatively soft laser welding part 50 can bear much plastic deformation, it can contribute to reduction of a springback.

  Next, a method for manufacturing the terminal 1 will be described. Since the terminal 1 of the present invention has a tubular caulking portion 30, the tubular caulking portion 30 is a terminal having a laser welded portion (see FIG. 1, the first laser welded portion and the second laser welded portion). As long as the above can be achieved, the production method is not limited.

A terminal 1 is a terminal in which a terminal is developed in a flat manner by forming the refractory metal layer and an Sn layer thereon by plating in a region that becomes a tubular caulking portion of a plate material made of a terminal base material (copper alloy or the like). The shape is punched into a terminal base material, and then the box portion 20 and the tubular caulking portion 30 are provided by bending. The refractory metal layer and the Sn layer may be plated on the entire surface (front surface and back surface) of the terminal base material, or may be formed on the entire surface of the plate material on the laser beam irradiation side, and the tubular caulking portion may be formed. You may plate in stripe form so that only the part to constitute or the field may be included. Alternatively, plating may be performed after punching into a developed shape of the terminal. In this case, a plating layer may also be formed on the end surface. Or you may form only in the area | region surface used as a laser welding part. Except for the case where the entire surface of the plate material is plated, for example, a mask may be formed on the surface not subjected to the plating treatment, and immersed in a plating bath to perform the plating treatment.
Further, the terminal may be formed in a shape in which the terminals are continuous in the longitudinal direction by punching from the plate material (chain type), or may be punched in a shape in which the terminals are individually developed from the plate material (single-wafer type). Since the tubular caulking portion 30 has a C-shaped cross section by bending from a flat surface by the subsequent bending process, the end surface of the open part is abutted and welded to form the tubular caulking part 30. As a preferable manufacturing method of the tubular crimping portion 30, laser welding using a fiber laser processing machine that oscillates near infrared laser light is performed.

Usually, copper alloys have a low absorption efficiency of laser light having an oscillation wavelength in the near-infrared region, so that there are cases where the weld width cannot be reduced or the heat affected zone (HAZ) cannot be reduced. Therefore, an Sn layer that absorbs near-infrared laser light better than copper or a copper alloy is formed on the surface of the terminal base material to be the laser weld 50, and laser light having a high energy density such as fiber laser light is used. Thus, the above problem is overcome. At that time, the copper in the terminal base material is prevented from diffusing into the Sn layer by the refractory metal layer except at the melting portion. For this reason, compared with the case where only the Sn layer is provided, an increase in contact resistance can be suppressed when the terminal is molded and used after welding.
Further, the laser welded portion 50 can be an annealed portion while welding the butted portion of the tubular crimped portion 30 by welding with fiber laser light. Thus, since the welding process and annealing process of the tubular crimping part 30 can be performed in one process, the terminal 1 can be manufactured efficiently.

  Since the Sn layer reflects less near-infrared laser light than the surface of copper or copper alloy, it absorbs near-infrared laser light. In the reflectance measurement of near infrared light using a spectrophotometer, the Sn layer used in the present invention has a reflectance of about 60 to 80%, which is lower than copper or a copper alloy having a reflectance of 90% or more. It has become. When the near-infrared laser light is irradiated onto the region where the Sn layer having high near-infrared laser light absorption is formed as described above, the Sn layer melts to form a molten pool, thereby absorbing the laser light. The base terminal base material melts and the melting region absorbs the laser beam to melt the butted portion of the terminal base material, and welding is progressing.

Further, the refractory metal layer and the Sn layer may be formed only on the surface of the terminal base material on the side where the laser beam irradiation is performed.
Alternatively, the refractory metal layer and the Sn layer may be formed only in a region where the tubular caulking portion 30 where the laser light irradiation of the terminal substrate is performed is formed.
In this case, when forming a terminal base material having a shape in which a terminal is developed by punching a plate made of a copper alloy, it includes a portion to be irradiated with laser light before punching, that is, a tubular caulking portion 30 and The refractory metal layer and the Sn layer are formed in a strip shape on the plate so as to include a portion to be formed. Usually, since a plurality of terminal base materials are produced by punching a single plate material by punching, a plurality of terminal base materials can be formed without forming a refractory metal layer and an Sn layer for each terminal base material. Since the refractory metal layer and the Sn layer can be formed collectively, the number of processes is reduced.
Furthermore, the refractory metal layer and the Sn layer may be formed only in a region where the terminal base material is irradiated with laser light. In this case, the refractory metal layer and the Sn layer can be saved.

  Since it changes depending on the material of the terminal base material constituting the terminal 1, it cannot be generally said. However, if the terminal base material is a copper alloy having an Sn layer formed on the outermost surface, the surface Sn is irradiated by near infrared laser light irradiation. The layer absorbs laser light and melts to form a molten pool. Further, the heat and thermal energy converted into light energy by the irradiation of the laser light are propagated, and the Sn layer, the refractory metal layer, and the copper alloy of the terminal base material 32 are melted. The metal tin, refractory metal, and metal copper melted after laser light irradiation solidify, and the butted portions are joined to form the laser weld 50. Therefore, the laser welding part 50 is provided because a terminal base material is heated up more than melting | fusing point. Specifically, by raising the butting portion of the tubular caulking portion 30 to a temperature not lower than the melting point and not higher than the boiling point of the terminal base material including the tin layer and the high melting point metal layer, and performing laser welding by holding for a predetermined time if necessary. A laser weld 50 is formed. Usually, since the laser beam is swept, the temperature of the laser beam irradiation region may be set to be equal to or higher than the melting point of the terminal substrate including the tin layer and the refractory metal layer by appropriately determining the sweep rate. . Preferably, the laser beam irradiation conditions are adjusted so that the terminal base material 32 is melted through by laser beam irradiation.

  The laser welding uses near infrared laser light. The near-infrared laser beam has an oscillation wavelength of 700 nm to 2.5 μm, and preferably a laser beam having an oscillation wavelength of 1000 nm to 2000 nm. Examples of such laser light include yttrium (Yb) -doped glass fiber laser light (oscillation wavelength 1084 nm), erbium (Er) -doped glass fiber laser light (oscillation wavelength 1550 nm), and the like.

  For the welding, a fiber laser device that continuously oscillates near-infrared laser light is used, but the tubular caulking portion 30 may be formed by welding using a laser device different from this. For example, there are a YAG laser beam oscillation device, a glass laser beam oscillation device, etc. that continuously oscillate, a laser beam oscillation device that performs pulse oscillation (preferably high-speed pulse oscillation), and the like. It is preferable to use a fiber laser oscillator because of its thinness and stability of continuous laser oscillation.

FIG. 6 is a diagram schematically showing one state during manufacture of the terminal 1 of the present invention.
As shown in FIG. 6, laser light L emitted from a fiber laser welding apparatus FL that oscillates near-infrared laser light having a wavelength of 1084 nm ± 5 nm is irradiated so as to cover the butting portion 37 of the tubular caulking portion 30, and laser light is emitted. Is converted into heat, the Sn layer and the refractory metal layer on the butt portion 37 first propagates, and then the fusion heat energy also propagates, and the terminal base material (Cu) itself of the butt portion 37 penetrates. Then, it is melted until it is cooled, and then cooled to provide the laser weld 50. The laser welding part 50 can be provided by a laser heating process at or above the melting point of the welding material. However, if the energy of the fiber laser beam L is too high, or if the energy density is too low, if the laser beam irradiation time is long, the heat-affected zone will be formed over a wider range than necessary, and in extreme cases it will be a tubular caulking. The whole part 30 will be softened. Therefore, the fiber laser light L is preferably welded at an output of 100 to 400W. Moreover, the laser welding part 50 is provided in a suitable range by adjusting sweep speed.

  If the width | variety of the said terminal base material is a width | variety which can be pierce | punched, for example by press work, there will be no restriction | limiting in particular. For example, it is 10 to 60 mm, preferably 15 to 40 mm.

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

  As shown in FIG. 7, a copper alloy sheet 5 is coated with a refractory metal layer (not shown) (shown as “undercoat” in the table) as shown in Table 1 and Sn as the outermost layer thereon. After forming a layer (not shown) in a stripe shape so as to include a region to be a tubular caulking portion, the plate material 5 is punched out and processed into a shape in which terminals are expanded so as to be continuous in the longitudinal direction (chain type) Then, a plurality of terminal base materials 32 were produced. Furthermore, the end surfaces 30S that are the butted portions of the tubular caulking portion developing portion 30a were butted together to produce a tubular caulking portion 30 forming portion 30b (see FIG. 8). At this time, the end faces 30 </ b> S are brought into contact with each other to form a butt portion 37. Then, as described with reference to FIG. 6, along the abutting portion, both sides thereof are irradiated by a near-infrared laser beam and welded by penetrating a length of 10 mm, and the tubular caulking portion is joined. A terminal sample was prepared. The term “terminal sample” as used herein refers to a terminal that has not yet been sealed at the tip and has a tubular caulking portion that includes only a laser welded portion (first laser welded portion) 50. By this welding, an annealed part was also obtained in the tubular crimped part. Moreover, the number of blowholes was evaluated as weldability by changing various conditions.

  Although omitted in the present embodiment, a terminal is obtained by further performing the following process on the above terminal sample. First, in order to close the end portion of the tubular caulking portion on the transition portion side, the base materials at the end portions of the tubular body are overlapped, the overlapped portion is welded (overlap welding), and the tip sealing portion (the second sealing portion) Laser welded part) 52 is provided. Furthermore, it becomes an independent terminal by separating the terminal from the carrier 38.

(Examples 1-7)
As a terminal base material, Furukawa Electric Co., Ltd. copper alloy FAS-680 (trade name, thickness 0.25 mm, H material) was used.
The alloy composition of FAS-680 is 0.15% by mass of tin (Sn), 0.5% by mass of zinc (Zn), 2.3% by mass of nickel (Ni), and 0.55% by mass of silicon (Si). % And magnesium (Mg) 0.1% by mass, the balance being copper (Cu) and inevitable impurities. FAS-680 has a melting point of 1078 ° C. (liquid phase), a specific heat of 377 J / (kg · K), a thermal conductivity of 170 W / (m · K), and a linear expansion coefficient of 17.7 × 10 ⁻⁶ / K (20 ˜300 ° C.), and conductivity 40% IACS. Further, the tensile strength is 600 to 700 N / mm ² , the elongation (tensile elongation at break, the same applies hereinafter) is 15% or more, the 0.2% proof stress is 500 to 600 N / mm ² , and the Vickers hardness is 160 to 220 Hv. is there.

  After electrolytic degreasing and activation treatment, a refractory metal layer (Pd layer in this embodiment) is formed on the surface of the terminal base material by refractory metal plating treatment (Pd plating in this embodiment), and Sn plating is further performed. An Sn layer was formed by the treatment.

The experimental conditions are as follows.
<Plating pretreatment (electrolytic degreasing treatment, acid dipping treatment)>
(Electrolytic degreasing)
Treatment liquid: 10% sodium hydroxide aqueous solution Treatment temperature: 60 ° C
Cathode current density: 3.5 A / dm ²
Treatment time: 30 seconds (acid dipping treatment)
Treatment liquid: 10% sulfuric acid aqueous solution Treatment temperature: 25 ° C
Immersion processing time: 30 seconds

<Pd plating treatment>
Treatment liquid: Pd (NH ₃ ) ₂ Cl ₂ : 45 g / liter, NH ₄ OH: 90 ml / liter, (NH ₄ ) ₂ SO ₄ : 50 g / liter Treatment temperature: 30 ° C.
Current density: 1 A / dm ²
Treatment time: The treatment time was adjusted for each thickness of the plating layer. The thickness of the Pd plating layer is 0.05 μm in Example 1, 0.1 μm in Example 2, 0.3 μm in Example 3, 0.5 μm in Example 4, 0.8 μm in Example 5, and Example. 6 was adjusted to 1.0 μm, and Example 7 was adjusted to 1.2 μm.

<Sn plating treatment>
(Sn plating conditions)
Treatment liquid: Tin sulfate: 80 g / liter, Sulfuric acid: 50 ml / liter Treatment temperature: 25 ° C.
Current density: 3 A / dm ²

(Examples 8 to 12)
As the terminal base material, the same terminal base material as used in Example 4 was used, and a refractory metal plating treatment of each of Ru, Rh, Os, Ir, and Pt was performed using a commercially available plating bath. A terminal sample was prepared in the same manner as in Example 4. The treatment temperature, current density, and treatment time were appropriately adjusted according to a conventional method for each metal type so as to have a predetermined plating thickness (0.5 μm).

(Example 13)
A terminal sample was prepared in the same manner as in Example 4 except that in Example 4, a copper alloy FAS-820 manufactured by Furukawa Electric Co., Ltd. was used instead of FAS-680.
The alloy composition of FAS-820 is 0.15% by mass of tin (Sn), 0.5% by mass of zinc (Zn), 2.3% by mass of nickel (Ni), and 0.65% by mass of silicon (Si). %, Magnesium (Mg) 0.1 mass%, and chromium (Cr) 0.15 mass%, with the balance being copper (Cu) and inevitable impurities. FAS-820 has a melting point of 1078 ° C. (liquid phase), a specific heat of 377 J / (kg · K), a thermal conductivity of 157 W / (m · K), and a linear expansion coefficient of 17.5 × 10 ⁻⁶ / K (20 ˜300 ° C.), and conductivity 38% IACS. Moreover, tensile strength is 730-830 N / mm < ² >, elongation is 7% or more, 0.2% yield strength is 675-775 N / mm < ² >, and Vickers hardness is 220-260 Hv.

(Example 14)
A terminal sample was prepared in the same manner as in Example 4 except that in Example 4, a copper alloy MAX-375 made of Mitsubishi Shindoh was used instead of FAS-680.
The alloy composition of MAX-375 is 0.5 mass% tin (Sn), 0.5 mass% zinc (Zn), 2.85 mass% nickel (Ni), and 0.7 mass silicon (Si). It is contained by mass and the balance is copper (Cu) and inevitable impurities. The melting point of MAX-375 is 1085 ° C. (liquid phase), the specific heat is 382 J / (kg · K), the thermal conductivity is 180 W / (m · K), and the linear expansion coefficient is 17.1 × 10 ⁻⁶ / K (20 ˜300 ° C.), and conductivity 40% IACS. Moreover, tensile strength is 750-850 N / mm < ² >, elongation is 6% or more, 0.2% yield strength is 710-830 N / mm < ² >, and Vickers hardness is 210-270 Hv.

(Example 15)
A terminal sample was prepared in the same manner as in Example 4 except that in Example 4, a copper alloy MAX251 made by Mitsubishi Shindoh was used instead of FAS-680.
The alloy composition of MAX251 contains 0.5 mass% tin (Sn), 1 mass% zinc (Zn), 2 mass% nickel (Ni), and 0.5 mass% silicon (Si), and Copper (Cu) is contained by 95% by mass or more, and the balance is inevitable impurities. The melting point of MAX251 is 1085 ° C. (liquid phase), the specific heat is 382 J / (kg · K), the thermal conductivity is 194 W / (m · K), and the linear expansion coefficient is 17.1 × 10 ⁻⁶ / K (20 to 300). ° C), and conductivity 48% IACS. Further, the tensile strength is 500 to 600 N / mm ² , the elongation is 6% or more, the 0.2% proof stress is 440 to 580 N / mm ² , and the Vickers hardness is 140 to 200 Hv.

(Example 16)
A terminal sample was prepared in the same manner as in Example 4 except that tough pitch copper (C1100 (JIS) manufactured by Furukawa Electric Co., Ltd.) was used instead of FAS-680 as the terminal substrate.

(Comparative Examples 1-2)
In Example 4, a terminal sample was prepared in the same manner as in Example 4 except that the thickness of the Pd layer of the refractory metal layer was 0.03 μm in Comparative Example 1 and 1.5 μm in Comparative Example 2.
(Comparative Example 3)
In Example 1, neither a refractory metal layer nor an Sn layer was formed. Otherwise, a terminal sample was produced in the same manner as in Example 1.
(Comparative Example 4)
In Example 1, a terminal sample was produced in the same manner as in Example 1 except that only the Sn layer was formed without forming the refractory metal layer.

  In any of the above cases, after bending into a terminal shape (see FIG. 8), opposing end faces that form the tubular caulking portion of the terminal sample are butted together and joined by laser welding that irradiates the following near infrared laser light. A terminal sample having a tubular caulking portion was formed.

The laser welding conditions are as follows.
(1) Laser welding apparatus: Furukawa Electric Co., Ltd. single mode fiber laser ASF1J221 (trade name)
Laser light source: Yb-doped glass fiber laser oscillator Laser light oscillation wavelength: 1084 ± 5 nm
Maximum laser beam output: 500W (continuous oscillation)

(2) Laser light irradiation conditions Laser light output: 400 W (used for continuous oscillation)
Laser light sweep speed: 135 mm / sec.
Laser light sweep distance: 10mm
All conditions Just focus laser irradiation (spot diameter size: 20μm)

The contact resistance was measured and evaluated as follows.
The contact resistance value is obtained by measuring the electrical resistance value between the crimping part and the electric wire and subtracting the resistance value for the electric wire. The electrical resistance value was measured using a Hioki 3560 AC Milliom HiTester (trade name). “A (excellent)” if the calculated contact resistance value is 0.5 mΩ or less, “B (good)” if it is higher than 0.5 mΩ and 0.7 μm or less, and “C (impossible)” if it is greater than 0.7 mΩ. ".

Regarding the weldability of the laser welded portion (first laser welded portion) 50 after laser welding, “weldability (number of blow holes)” was evaluated.
The “number of blow holes” is an index of welding defects, and was evaluated by counting the number. The smaller the number of blow holes, the better the weldability.
The number of blowholes was measured by taking a transmission X-ray photograph of the entire laser welded part after laser welding and counting the number of blowholes in the welded range. In this example, the number of blow holes in the sweep area was counted. In addition, the number of blowholes of 10 samples prototyped under the same conditions was averaged, and a value obtained by rounding off the decimal place with the first place as a significant figure was adopted. If the number of blowholes exceeds 10, the surface roughness of the welded portion increases, weld internal defects, etc. increase, so that 0 to 10 are represented as “A (excellent)” by using the threshold as 11 to 20 "B (good)", the case where it was not possible to weld because of exceeding 20 pieces or cracking at the welded part was expressed as "C (impossible)" and evaluated.

  The various test results and evaluation results are shown in Table 1.

As is apparent from Table 1, in Examples 1 to 16, the contact resistance is low, particularly 0.5 mΩ or less when the thickness of the refractory metal layer is 0.5 to 1.2 μm, and the blowhole after welding The number was 20 or less and had good contact resistance and weldability.
On the other hand, in Comparative Example 2, the number of blow holes exceeded 20 and the weldability was inferior. Further, in Comparative Example 3, the welded portion was cracked and could not be welded. Comparative Examples 1, 3, and 4 except Comparative Example 2 were inferior in contact resistance.

DESCRIPTION OF SYMBOLS 1,100,101 Terminal 5 Board | plate material 10 Termination connection structure 20 Box part 30,80,90 Tubular crimping part 30S End surface 31,81,91 Insert port 32 Terminal base material 33 Inner wall surface of tubular crimping part 34a, 34b Electric wire latching groove 37 Butting section 38 Carrier 40 Transition section 50, 500, 501 Laser welding section (first laser welding section)
52, 502, 503 Tip sealing portion (second laser welding portion)
60 Coated wire 61 Insulation coating 82 Coated crimping part 83, 85 Reduced diameter part 84 Conductor crimping part FL Fiber laser welding equipment L Fiber laser beam

Claims (11)

A method of manufacturing a terminal having a tubular caulking portion that is crimp-bonded to an electric wire,
A refractory metal layer made of a refractory metal selected from any one of ruthenium, rhodium, palladium, osmium, iridium and platinum on at least a portion forming the tubular caulking portion with respect to a plate made of copper or a copper alloy Is formed with a thickness of 0.05 μm to 1.2 μm,
Forming a tin layer on the refractory metal layer;
Forming the terminal base material by punching out the plate material in which the refractory metal layer and the tin layer are formed in a developed view of the terminal,
Bending a tube expanding portion that becomes a portion forming the tubular caulking portion of the terminal base material, but facing opposite ends of the tube expanding portion to form a butted portion;
The manufacturing method of the terminal which has each process which joins the said butt | matching part by laser welding and forms the said tubular crimping part in this order. A method of manufacturing a terminal having a tubular caulking portion that is crimp-bonded to an electric wire,
A terminal base material is formed by punching a plate made of copper or a copper alloy into a developed view of the terminal,
A refractory metal layer made of a refractory metal selected from any one of ruthenium, rhodium, palladium, osmium, iridium, and platinum is formed on the tube development portion that forms the tubular caulking portion of the terminal base material. .05 μm to 1.2 μm thick,
Forming a tin layer on the refractory metal layer;
Bending the pipe expanding portion, butting the opposite ends of the pipe expanding portion together to form a butt portion;
The manufacturing method of the terminal which has each process which joins the said butt | matching part by laser welding and forms the said tubular crimping part in this order.   Furthermore, the manufacturing method of the terminal of Claim 1 or 2 which has the process of forming the front-end | tip sealing part by obstruct | occluding the edge part by the side of the transition part of the said tubular crimping part by laser welding.   The method for manufacturing a terminal according to claim 1, wherein the refractory metal layer is formed by plating.   5. The method of manufacturing a terminal according to claim 1, wherein the refractory metal layer is formed on the surface of the tube development portion on the laser welded side, and then the tin layer is formed thereon. .   6. The method of manufacturing a terminal according to claim 1, wherein the refractory metal layer is formed in the laser welded region of the tube development portion, and then the tin layer is formed thereon.   The method for manufacturing a terminal according to any one of claims 1 to 6, wherein the refractory metal layer is formed on the opposing end portion of the tube development portion, and then the tin layer is formed thereon.   The method of manufacturing a terminal according to claim 1, wherein the laser welding uses a laser beam having an oscillation wavelength in a near infrared region. A terminal having a tubular caulking portion that is crimp-bonded to an electric wire,
The terminal base material forming the terminal is made of copper or a copper alloy,
The tubular caulking portion is formed by bending the tube deployment portion of the terminal base material and abutting the opposite ends thereof, and the abutting portion is joined by laser welding,
A refractory metal layer made of a refractory metal selected from any one of ruthenium, rhodium, palladium, osmium, iridium, and platinum is 0.05 μm to 1.2 μm in thickness on the laser-welded terminal base material. Formed,
A tin layer is formed on the refractory metal layer,
Terminals that prevent diffusion of the terminal base material and tin in areas other than those melted by laser welding. A method for producing an end connection structure of an electric wire, wherein the terminal produced by the method for producing a terminal according to any one of claims 1 to 8 and a covered electric wire are crimp-connected at a tubular caulked portion of the terminal. And
Insert the covered electric wire with the core wire exposed from the end into the tubular caulking portion,
A method for manufacturing an end connection structure for electric wires, wherein the tubular caulking portion is caulked and the covered electric wire is crimped and connected to the tubular caulking portion.   An electric wire terminal connection structure in which the terminal according to claim 9 and a covered electric wire are crimped and connected at a tubular caulking portion of the terminal.

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