JPH09314353A - Resistance welding method and construction of body to be welded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure high joining strength without variance by causing two bodies to be joined only in contact each other through an embossed part so as not to incur shunting of welding current at resistance welding and preventing remaining of foreign matter on a joining part so as to incur lowering of joining strength. SOLUTION: A metal plate part 9 constituting a terminal 7 is covered with the insulation material 10 made of a thermoplastic resin of polybutylene- trephthalate(PBT), polycarbonate(PC), etc., at the state the tip of embossed part 9a is exposed. Thus, when holding with electrodes 13, 14 for resistance welding, the exposed tip part only is always brought into point contact with the terminal 7 and lead 3a. Further, because the embossed part 9a is exposed from the insulation material 10, the insulation material 10 is not left on the joined part after resistance welding as foreign matter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to two objects to be welded which are welded to each other, such as a terminal on an electronic component side and a terminal on a substrate base material side which are welded to each other for mounting an electronic component. The present invention relates to a resistance welding method for welding by resistance welding and a structure of an object to be welded.

[0002]

2. Description of the Related Art Conventionally, assembling of electronic parts to a mounting board is carried out by a micro resistance welding method in which terminals (leads) provided on electronic parts to be mounted are mounted on terminals (terminals) provided on the board side. May be performed by welding.

Usually, in micro resistance welding, the contact area between the terminal and the lead is made small to converge the current during energization to promote heat generation, so that a protrusion (emboss) is formed on the terminal.
Had been formed.

For example, as shown in FIG. 7A, a terminal 52 joined to the flat lead 51 is formed with a substantially cylindrical emboss 53 so that the flat lead 51 and the terminal 52 are connected to the emboss 53. Pair of electrodes for resistance welding (plus electrode and minus electrode) 54 in contact with each other
The embossment 53 is sandwiched by a and 54b from the outside, and the emboss 53 is exothermicly melted by keeping energization for a certain period of time, and then the two are joined by solidification of the melted portion.

Further, as shown in FIG. 7B, a projecting emboss 57 is formed on the terminal 56 joined to the round lead 55. Even if the contact position of the round lead 55 with respect to the terminal 56 is slightly shifted up and down, the embossment 57 extends in the direction orthogonal to the direction of the round lead 55, so that a constant contact area is always secured between the two. Also in this case, similarly, the terminal 56 and the round lead 5
In a state in which 5 and 5 are in contact with each other by the emboss 57, they are sandwiched by a pair of resistance welding electrodes 54a and 54b from the outside, and are energized and held for a certain period of time to join the two at their contact portions.

[0006]

However, as shown in FIG. 8A, when the flat lead 51 is joined, the embossment 5 is used.
When the terminal 52 and the flat lead 51 are sandwiched by the resistance welding electrodes 54a and 54b at a position deviated from the position corresponding to 3, the flat lead 51 is inclined and sandwiched with respect to the terminal 52 due to the protrusion of the emboss 53. Embossed 53
Both parts will come into contact with each other. In this case, since there are two contact points, the energizing current at the time of resistance welding is shunted, and sufficient heat generation cannot be obtained, so that the joining becomes unsuccessful.

Also, as shown in FIG. 8B, when the round leads 55 are joined together, if the round leads 55 are deformed such as bent, they will come into contact with each other at two locations other than the embossed portion 57. Will be done. Therefore, in this case as well, the current flow during resistance welding is shunted, and sufficient joint strength cannot be obtained.

As a method for solving such a problem,
For example, Japanese Patent Application Laid-Open No. 57-190786 discloses a resistance welding method as shown in FIG. As shown in the figure, a plurality of projections 63 are formed on the joint surface of the material 62 to be welded to the base material 61, and the joint surface is thinly coated with an insulating layer 64 such as soft vinyl chloride. ing. The insulating layer 64 is locally destroyed by pressing the protrusion 63 on one of the resistance welding electrodes 65a and 65b. Therefore, when energized, a current flows only between the protrusion 63 where the insulating layer 64 is destroyed and the base material 61, so that even if the base material 61 and another protrusion 63 come into contact with each other, the sneak current can be prevented. The welded portion can be welded to a required strength with a predetermined current value.

However, according to this resistance welding method, when the insulating layer 64 of the projection 63 is not destroyed when the resistance welding electrode 65a is pressed, or when the destruction is not sufficient, the necessary bonding strength is obtained. Not obtained, resulting in poor welding.
Further, if the broken pieces of the insulating layer 64 remain in the joint portion as foreign matter, there is a possibility that the joint strength may be weak such that the joint is apparently joined but is immediately detached when pulled.

The present invention has been made in view of the above problems, and an object thereof is to bring two objects to be welded into contact with each other only by a protrusion so as not to cause a shunt of a current flowing during resistance welding. It is an object of the present invention to provide a resistance welding method and a structure of a body to be welded, by which it is possible to always maintain a high joint strength without variation by preventing foreign matter from remaining in a joint portion which causes a decrease in joint strength.

[0011]

In order to solve the above problems, in the invention according to claim 1, a protrusion is formed on one of the two objects to be welded, and the objects to be welded are contacted by the protrusion. Resistance welding energization is carried out in a state, and is a resistance welding method for concentrating the current during resistance welding so as to promote heat generation, wherein at least the tip of the protrusion is exposed on the body to be welded with an insulating material. Insulation material coating step for coating, and current welding in which electricity is applied between the objects to be welded at least after the insulating material is covered in a state where the objects to be welded are in contact with each other on the side where the projections are formed. And the process.

According to a second aspect of the present invention, there is provided a body to be welded in which a projection for concentrating a current during resistance welding is formed, and an insulating material exposes at least the tip of the projection to the body to be welded. It is coated so that

According to a third aspect of the present invention, in the structure of the body to be welded according to the second aspect, the insulating material has a coating thickness slightly shorter than the protruding length of the protrusion so that only the tip end portion of the protrusion is exposed. It is covered with.

According to the invention of claim 4, in the structure of the object to be welded according to claim 2 or 3, the insulating material is a thermoplastic resin. Therefore, according to the invention described in claim 1, in the insulating material coating step, at least the tip of the projection is formed on the projection forming surface of the one of the two objects to be welded to be resistance-welded having the projection. The insulating material is covered with the exposed portion. In the energization welding step, energization using a resistance welding electrode is performed between the objects to be welded at least after covering the insulating material with the objects to be welded in contact with the projection forming surface. Therefore, the two objects to be welded are in contact with each other only at the tips of the protrusions regardless of their relative positions.
The shunt of the energizing current is surely avoided, and the current concentrates only on the protrusion contact portion. As a result, the protrusion contact portion is sufficiently heated and melted, so that the both are always bonded with required strength. Further, since the tips of the protrusions are exposed from the insulating material, it is possible to prevent the insulating material from remaining as foreign matter in the joint portion, and to prevent the reduction of the joint strength due to the foreign matter remaining in the joint portion.

According to the second aspect of the present invention, since the projection of the object to be welded is covered with the coating material so that at least the tip thereof is exposed, the object to be welded is brought into contact with the member to be welded. In such a case, the two are always in contact with each other only by the tips of the protrusions regardless of their relative positions. for that reason,
The shunting of the current during resistance welding energization is avoided, and the current concentrates on the contact portion of the protrusion and sufficiently heats and melts, so that the welding is always performed with the necessary joining strength. In addition, since the tip end of the protrusion is exposed from the insulating material, it is possible to prevent the insulating material from remaining as a foreign matter in the joint portion, and the joint strength is not reduced due to the foreign matter.

According to the third aspect of the present invention, the insulating material is coated with a coating thickness slightly shorter than the projection length of the projection so that only the tip of the projection is exposed. Even if it is sandwiched by the resistance welding electrodes in other parts,
Both the objects to be welded are prevented from inclining and coming into contact with each other.

According to the fourth aspect of the invention, since the insulating material is a thermoplastic resin, the insulating material around the protrusions that is melted (softened) by the heat generated during resistance welding contributes to the enhancement of the bonding strength. Therefore, it is possible to secure higher bonding strength.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 5, the electronic component-mounted product 1 is configured by mounting the electronic components 3 and 4 on the base component 2. The base component 2 includes, for example, a frame part 5 made of aluminum and a base 6 fixed to the frame part 5 in a housed state. The base 6 is formed in a resin-molded state by insert molding performed by setting a substrate (not shown) in the frame portion 5 in a housed state and setting it in a mold.

Plate-shaped terminals 7 and 8 as terminals to be welded and terminals for mounting electronic parts are extended on the base 6. The electronic components include an electronic component 3 in which a flat lead 3a as a welded object is extended from the substrate, and an electronic component 4 such as a coil or a capacitor in which a round lead 4a as a welded object is extended. The electronic components 3 and 4 have their respective leads 3
It is mounted on the base 6 by welding the terminals a and 4a to the terminals 7 and 8. In the present embodiment, the terminal 7,
8 includes a terminal 7 for mounting the electronic component 3 having the flat lead 3a, and an electronic component 4 having the round lead 4a.
There are two types, namely, a terminal 8 for mounting the.

As shown in FIGS. 1 and 2, the terminal 7
Is made of a copper alloy that forms a body to be welded, which extends from the base 6 in a substantially rectangular plate shape and has a cylindrical embossment 9a as a protrusion formed on the surface to be welded to the flat lead 3a. For example, a metal plate portion 9 made of brass) is provided. The surface of the metal plate portion 9 on which the embossment 9a is formed is covered with an insulating material 10 with the tip of the embossment 9a exposed.

Further, as shown in FIGS. 3 and 4, the terminal 8 extends from the base 6 into a substantially square plate shape, and
A metal plate portion 11 made of a copper alloy (for example, brass) constituting a body to be welded is provided with a protruding embossment 11a as a protrusion formed on a surface to be welded to the round lead 4a.
The ridged embossment 11a is formed in a protruding state by bending the metal plate portion 11. Metal plate part 1
The first embossing 11a forming surface side is covered with an insulating material 12 in a state in which the tip end portion of the embossing 11a is exposed along the extending direction of the ridge.

The insulating materials 10 and 12 are made of a thermoplastic resin such as polybutylene terephthalate (PBT) or polycarbonate (PC). The insulating materials 10 and 12 are coated together during insert molding for resin molding covering the base 6. For example, a state in which only the tips of the embosses 9a and 11a are exposed by injecting a resin into the mold while masking the inner wall surface of the mold for insert molding that does not cover the insulating materials 10 and 12. Is covered with an insulating material 10. Insulation materials 10 and 12 are PB
Other than T and PC, those having relatively high insulation performance can be used. Particularly, in this embodiment, the heating temperature around the embossments 9a and 11a during welding energization may be about 20.
It has a melting point of 0 to 300 ° C (PBT
Has a melting point of 224 ° C. and PC has a melting point of 240 ° C.). The materials of the leads 3a and 4a are made of copper-based metal (for example, brass).

During micro resistance welding, the terminal 7,
8, the leads 3a and 4a are in contact with the tips of the embosses 9a and 11a exposed on the insulating layer 10 side, and sandwiched by a pair of resistance welding electrodes (plus and minus electrodes) 13 and 14 from the outside. , By applying a voltage.

Next, the operation of the terminals 7 and 8 configured as described above will be described. The base 6 in the frame portion 5 that constitutes the base component 2 is formed by resin-molding a substrate (not shown) that extends the metal plate portions 9 and 11 into the frame portion 5 by insert molding. The metal plate portions 9 and 11 are attached to the substrate after being processed to form the embossments 9a and 11a in advance, and this insert molding is performed so that the metal plate portions 9 and 11 are extended from the base 6. Is performed using an insert molding die. At the time of this insert molding, the embossing 9 is applied to one side surface of the metal plate portions 9, 11.
The resin is coated with the tips of a and 11a exposed. An insulating thermoplastic resin such as PBT or PC is used as the insert molding resin. Therefore, base 6
The terminals 7 and 8 extending from are formed in a state in which the insulating materials 10 and 12 made of PBT, PC, or the like are covered with the tips of the embosses 9a and 11a exposed.

Next, a procedure for micro resistance welding the electronic components 3 and 4 will be described. First, the leads 3a and 4a of the electronic components 3 and 4 to be mounted are set with the embossed surfaces 9a and 11a forming surface (exposed surface) in contact with the terminals 7 and 8 to be welded. And terminal 7,
8 and the leads 3a, 4a are sandwiched from the outside by two resistance welding electrodes 13, 14.

For example, even if the resistance welding electrodes 13 and 14 sandwich the terminal 7 and the flat lead 3a at a portion other than the embossment 9a, the flat lead 3a only contacts the surface of the insulating material 10 so that the flat plate 3a and the flat plate 3a are flat. Embossed 9a with lead 3a
Point contact only at the tip of. Further, since the bent round lead 4a only hits the covering surface of the insulating material 12, the metal plate portion 11 and the round lead 3a make point contact only at the tip of the emboss 11a. Particularly, in this embodiment, the insulating material 1
Since the coating thickness of 0, 12 is set to a value slightly smaller than the projecting length of the embossments 9a, 11a so that only the tips of the embossments 9a, 11a are exposed, the welding electrodes 13, 1
Even if the terminals 7 and 8 are sandwiched by the parts 4 other than the embosses 9a and 11a, the terminals 7 and 8 and the leads 3a and 4a contact each other in a substantially parallel posture without being tilted so much.

The terminals 7 and 8 and the leads 3a,
4a in contact with the electrodes 13 and 14 for resistance welding
A predetermined voltage is applied between them and resistance welding is performed. When energized, the electric current concentrates and flows only on the point contact portions at the tips of the embosses 9a and 11a. Therefore, the current when energized does not flow. As a result, the current concentrates only on the point contact portion, causing sufficient heat generation due to the predetermined current.

When heat is generated at a temperature of about 800 ° C. or higher at which the copper alloys, which are the materials of the metal plate portions 9 and 11 and the leads 3a and 4a, melt, the metal at the point contact portions begins to melt. Before and after this, the melting points of the insulating materials 10 and 12 around the embossments 9a and 11a (for example, 224 ° C for PBT and 240 ° C for PC)
It begins to melt gradually from the part that became. Since the load is applied by the resistance welding electrodes 13 and 14,
The molten portions of the embosses 9a and 11a are spread by the load, if the molten resin around them is forced outward. In this way, the welding area is secured.

At this time, the molten metal at the point contact portions at the tips of the embosses 9a and 11a and the molten resin of the insulating materials 10 and 12 have low compatibility and also have a considerable difference in specific gravity, so that they do not mix with each other. When the embosses 9a and 11a are melted and the terminals 7 and 8 and the leads 3a and 4a come close to each other to some extent due to the load from the resistance welding electrodes 13 and 14, the molten resin of the insulating materials 10 and 12 causes the leads 3a and 4a to melt.
Come into contact with.

After a predetermined time (actually 1 second or less) has passed, when the current supply is stopped, the molten portion near the point contact is in a state where the materials of the terminals 7 and 8 and the leads 3a and 4a are mixed. It cools and solidifies. At this time, the insulating materials 10 and 12
The molten resin is also cooled and hardened, and the hardened resin also contributes to the joining between the terminals 7 and 8 and the leads 3a and 4a.

Leads 3a and 4 for terminals 7 and 8
A is point-contacted in a state where the metals directly contact with each other at the exposed tips of the embossments 9a and 11a, and from this state, energization for micro resistance welding is performed. Further, in this energization process, the molten metal at the point contact portions at the tips of the embosses 9a and 11a and the molten resin of the insulating materials 10 and 12 have low mutual compatibility and also have a large difference in specific gravity, so that they do not mix with each other. , The resin is only driven to the outside. Therefore, the molten resin and the like do not remain as foreign matter at the joint. Therefore, consistent high bonding strength can be obtained.

In this way, the electronic components 3 and 4 are mounted on the terminals 7 and 8 of the base 6 by micro resistance welding, and the electronic component mounted product 1 is manufactured. If necessary, silicon gel is injected into the frame 2 for the purpose of ensuring high insulation between the electronic components 3 and 4.

As described in detail above, according to the present embodiment,
The following effects are obtained. (A) The terminals 7 and 8 are formed by covering the metal plate portions 9 and 11 with the insulating materials 10 and 12 in a state where the tips of the embosses 9a and 11a are exposed.
8 and the leads 3a and 4a, the terminals 7 and 8 and the leads 3a and 4a are always embossed 9a and 1a.
It is possible to make point contact only with the tip of 1a. As a result, the energization current during micro resistance welding can be concentrated and flown to the contact portions at the tips of the embossments 9a and 11a without being divided. Therefore, the embossments 9a and 11a can be sufficiently melted so that the required bonding strength can always be obtained, and the bonding strength can always be sufficiently secured without variation.

(B) By making sure the point contact or the line contact so that the shunt current does not occur, the electric current can be concentrated and the electric power supply between the electrodes at the time of resistance welding can be made low power.

(C) Since the insulating materials 10 and 12 were coated with the tips of the embosses 9a and 11a exposed, the joints were broken as in the resistance welding method of FIG. 9 described in the prior art. It is possible to avoid a decrease in the bonding strength caused by the fragments of the coating layer remaining as foreign matter. Therefore, it is possible to further suppress the occurrence of variations in the bonding strength.

(D) Since the coating thickness is set so that only the tips of the embosses 9a and 11a are exposed from the insulating materials 10 and 12, the terminals 7 and 8 and the leads 3a, except the portions corresponding to the embosses 9a and 11a, Even if 4a is sandwiched by the resistance welding electrodes 13 and 14, the terminals 7 and 8 and the leads 3a and 4a can be set in a state in which they are in contact with each other in a substantially parallel manner without being tilted so much. As a result, the micro resistance welding is performed with the terminals 7 and 8 and the leads 3a and 4a set in the correct postures, so that it is possible to prevent excessive stress from being applied to the welded portions.

(E) The insulation resistance of the terminals 7 and 8 can be improved by coating the insulating materials 10 and 12, for example, the discharge caused by static electricity generated between the mounted electronic components 3 and 4 can be canceled. be able to. Further, it is possible to suppress the metal corrosion of the portions covered with the insulating materials 10 and 12, and to improve the environment resistance of the terminals 7 and 8.

The present invention is not limited to the above embodiments, but can be modified as follows without departing from the gist of the invention. (1) As shown in FIG. 6, an insulating material 23 for covering the metal plate portion 22 constituting the terminal 21 in a state where the tip of the embossing 22a as a projection is exposed is provided on the electrodes 13 and 14 for resistance welding. A configuration may be adopted in which the back surface side of the surface on which the emboss 22a is formed excluding the sandwiching area is covered. According to this configuration, the area covered by the insulating material 23 is increased, so that it is possible to further improve the dielectric strength and environment resistance of the terminal 21.

(2) The coating thickness of the insulating material 10, 12, 23 is not limited to a value such that only the tip of the emboss is exposed. If insulation is secured, the coating thickness of the insulating material can be changed as appropriate. For example, the coating thickness may be a sufficiently small value as compared with the protruding length of the emboss. With this configuration, it is possible to reliably suppress the shunt of the energizing current during micro resistance welding, and to use a small amount of the insulating material. Further, even if the objects to be welded are inclined and come into contact with each other, the point contact is made at the embossing, so that the necessary joining strength can be obtained after welding.

(3) The insulating material is not limited to the resin that is cured at room temperature. For example, the present invention may be applied using a gel resin as an insulating material. For example, silicon gel may be used. If the viscosity of insulating gel such as silicon gel is low to some extent, the terminal (metal plate in this case) should be lifted up by capillarity and the terminal should be covered with the tip of the emboss (projection) exposed. You can Therefore, the work of covering the insulating material can be simplified. Further, although silicon gel has only adhesiveness and does not enhance the bonding strength, its high insulating property also contributes to the improvement of dielectric strength and environmental resistance. Also,
A procedure may be adopted in which the silicon gel is raised with the embossment of the terminal and the lead in contact with each other. For example, even if the lead is in light contact with the metal plate of the terminal at a part other than the embossing, if the silicon gel penetrates into the contact part by capillary action so as to block the contact, the shunting of the energizing current during resistance welding will occur. It can be suppressed.

(4) The object to be welded on which the projection (emboss) is formed in the present invention is not limited to the terminal on the base component side on which the electronic component is mounted. For example, the flat lead 3a of the electronic component 3 may be embossed, and the flat lead 3a may be covered with an insulating material with the tip of the emboss exposed. With this configuration as well, the terminal and the flat lead can be brought into point contact with each other regardless of the positional relationship at the time of contact, so that the same effect as in the above embodiment can be obtained.

(5) The direction of the embossing 11a formed on the terminal 8 for welding the round lead 4a can be appropriately changed according to the joining direction. For example, a configuration in which a convex strip emboss is formed in a direction orthogonal to the extending direction of the terminal may be adopted.

(6) The material of the insulating material is not limited to the thermoplastic resin. For example, if a thermosetting resin is used in a state where the B stage is not completely cured, the insulating material can be spread by the molten metal to secure the bonding area. Alternatively, a thermosetting resin that is completely cured may be used, expecting only insulation. Also with this configuration, it is possible to always contact the object to be welded only with the projection (emboss) tip.

(7) The material of the objects to be welded such as terminals and leads is not limited to copper-based metals (for example, copper alloys such as brass). (8) The object to be welded is not limited to a mounting board such as a terminal or lead, or a terminal provided on an electronic component. For example, the present invention may be applied to assembly welding (spot welding) of an automobile or the like.

The invention grasped from the above embodiment and not described in the scope of the claims will be described below together with the effect thereof. (A) In any one of claims 2 to 4, the insulating material is covered up to the back surface side of the surface on which the projection is formed, leaving at least a portion where the resistance welding electrode abuts. According to this structure, the insulation resistance and the environment resistance of the object to be welded can be improved by being covered with the insulating material.

(B) A substrate part according to any one of claims 2 to 4, wherein the object to be welded according to any one of claims 2 to 4 is provided as a terminal. According to this configuration, the board component includes the welded body according to any one of claims 2 to 4 as a terminal, so that the electronic component to be mounted by resistance welding has sufficient strength for the board component. It can be mounted without variation.

(C) An electronic component assembled product in which an electronic component is mounted by resistance welding on the terminal provided on the board component described in (B). According to this configuration, since the electronic component-mounted product is configured by mounting the electronic component by resistance welding on the terminal provided on the board component according to claim 5,
The mounting strength of the electronic component can be made high without variation.

[0048]

Therefore, according to the invention described in claim 1, an insulating material coating step of coating the insulating material on the projection forming surface of the object to be welded with at least the tips of the projections exposed.
Since both of the objects to be welded are in contact with each other on the projection forming surface and at least an electric current welding step of energizing using the resistance welding electrode after covering the insulating material is provided, it does not depend on the positional relationship between the objects to be welded. Both welding objects can be brought into contact with each other only by the tips of the protrusions so as not to cause shunting of current when welding current is applied, and it is possible to prevent the insulating material from remaining as foreign matter at the joints. It can be secured without variation.

According to the second aspect of the present invention, since the projection of the object to be welded is covered with the insulating material so that at least the tip of the object is exposed, the two objects to be welded do not cause shunt when welding current is applied. In addition, since it is possible to make contact with only the tip of the protrusion and to prevent the insulating material from remaining as foreign matter at the joint, it is possible to secure sufficient joint strength without variation.

According to the third aspect of the present invention, since the insulating material is coated on the object to be welded with a coating thickness that exposes only the tips of the projections, both the objects to be welded are provided on the parts other than the contact parts of the projections. Even if the electrodes are sandwiched by the resistance welding electrodes, it is possible to prevent both the objects to be welded from inclining and contacting each other.

According to the fourth aspect of the invention, since the insulating material is a thermoplastic resin, the insulating material around the protrusions that has been melted (softened) at the time of heat generation by electric current can contribute to the enhancement of the bonding strength. High bonding strength can be secured.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state during resistance welding of a terminal and a flat lead according to an embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view showing a state during resistance welding of a terminal and a round lead.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a perspective view showing a board component for mounting electronic components.

FIG. 6 is a plan sectional view showing a terminal of another example.

FIG. 7 is a perspective view showing a terminal and a lead according to a conventional technique.

FIG. 8 is a plan sectional view of the same.

FIG. 9 is a side sectional view showing a conventional resistance welding method.

[Explanation of symbols]

3a ... Flat lead as a welded object, 4a ... Round lead as a welded object, 7, 8, 21 ... Terminals as a welded object and terminals, 9, 11, 22 ... Metal plate parts constituting the welded object , 9a, 11a, 22a ... Embossing as a protrusion, 13, 14 ... Electrodes for resistance welding.

Claims (4)

[Claims] 1. A projection is formed on one of two objects to be welded,
A resistance welding method in which resistance welding energization is performed in a state in which both objects to be welded are in contact with each other by the projections, and a current at the time of resistance welding is concentrated to promote heat generation, which is at least the object to be welded. An insulating material coating step of coating an insulating material in a state where the tips of the projections are exposed; A resistance welding method comprising: a current welding step of conducting current using a resistance welding electrode. 2. A body to be welded having a projection for concentrating a current during resistance welding, wherein the body to be welded is covered with an insulating material so as to expose at least the tip of the projection. The structure of the work piece. 3. The structure of the object to be welded according to claim 2, wherein the insulating material is coated with a coating thickness slightly shorter than the protruding length of the projection so as to expose only the tip portion of the projection. 4. The structure of the object to be welded according to claim 2, wherein the insulating material is a thermoplastic resin.