JP2002346757A - Projection-welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection-welding method with which the welding state having high reliability can be obtained by forming a welded nugget even in the case of the projection-welding of both coppers. SOLUTION: This projection-welding method is projection-welded by piling a copper terminal 1 to be welded, insert-formed in a resin formed product 2 and a copper welding terminal 3. In this way, when the projection-welding is performed by setting the size of the copper terminal 1 to be welded, projected from the resin formed product 2, the size of the welding terminal 3 and the size of the projection 4 to prescribed sizes, the welding nugget is formed between the terminal 1 to be welded and the welding terminal 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection welding method in which a copper or copper alloy welding terminal and a copper or copper alloy welding terminal or a lead wire of an electronic component are overlapped and subjected to projection welding.

[0002]

2. Description of the Related Art Conventionally, resistance spot welding has been widely used for welding steel, aluminum, and other thin plates to automobiles, vehicles, home appliances, and the like.

In this resistance spot welding method, two plates C and D to be joined are sandwiched between electrodes A and B as shown in FIG. ,
A large current is supplied from the AC power source E for a short time, and Joule heat is generated at the contact portion between the plate C and the plate D immediately below the electrodes A and B by contact resistance, thereby forming a spot-shaped fusion joint called a welding nugget. It has become. In FIG. 5, F is a welding nugget and G is a joining interface.

In the resistance spot welding method as described above, the currents and stresses are concentrated at the joint interface G by the electrodes A and B, and the joint can be formed. On the other hand, in the projection welding method, FIG. As shown in (1), a projection called a projection is provided at the joint, and the projection concentrates current and stress to form a fusion joint. In FIG. 6, A 'is a movable electrode, B' is a fixed electrode,
C and D are plates, E 'is a welding power source, F is a welding nugget, H'
Is the direction in which the movable electrode A 'is pressed, and I is the projection.

[0005] When performing such welding, if a fusion bonding part called a welding nugget is not formed, a bonding interface exists at the bonding part, and if used for a long time, cracks are generated from the bonding interface and progress. In the case of a product incorporating components, etc., this is one of the factors directly affecting the quality and reliability of the product itself.

However, in the projection welding of copper, since the thermal conductivity of copper is very high (about 5 times that of steel),
If the terminals are not welded in an appropriate shape when they are joined by welding, there is a problem that a welding nugget cannot be formed as shown in FIGS. If a welding nugget is not formed in this way, a very poor reliability is obtained.

Conventionally, high-temperature soldering is generally used for electrical connection between copper alloy terminals. However, especially for vehicle lighting applications, -40 ° C
However, there is a problem in that the joint strength decreases and deteriorates at the solder joint due to the repetitive action of the thermal stress under a cooling / heating cycle of 70 to 70 ° C.

In such a case, resistance welding as described above can be considered as a method for joining copper alloy terminals from the viewpoint of joining strength. However, since welding between copper alloys requires the use of a high melting point material for the welding electrode. Resistance heating occurs at the contact surface between the welding electrode and the copper alloy terminal that has been subjected to the conductive surface treatment, and a damaged part is formed in the conductive surface treatment of the terminal that has come into contact with the welding electrode.
Due to the deterioration of the terminal due to aging from the damaged part of the conductive surface treatment during use, there is a problem that the electrical connection does not come off when the light source is replaced, and it has not been implemented. In welding conditions that do not damage the conductive surface treatment at the contact surface with the welding electrode,
Since the molten structure of the two metals, that is, the welding nugget is not formed, the joining strength is weak, and there is a problem in the long-term reliability of the joint.
Further, when electroless nickel plating as a conductive surface treatment intervenes at the bonding interface, there is a problem that cracks are likely to occur because the phosphorus component used during the plating treatment becomes an inclusion in the welded portion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above description, and an object of the present invention is to provide a projection welding method capable of forming a welding nugget to achieve a highly reliable welding state even in projection welding of copper. Removed conductive surface treatment at the joint interface during projection welding of copper alloy terminals with conductive surface treatment used near the light source, and damaged the conductive surface treatment at the contact surface with the welding electrode It is an object of the present invention to provide a projection welding method that can form a welding nugget without causing the welding to be in a highly reliable welding state.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a projection welding method according to the present invention is directed to a projection welding method in which a copper welded terminal and a copper welded terminal which are insert-molded in a resin molded product are overlapped and projection-welded. A method wherein the size of a terminal to be welded projecting from a resin molded product, the size of a welding terminal, and the size of a projection are set to a predetermined size, and the projection welding is performed between the terminals to be welded and the welding terminal. It is characterized by forming a nugget.

At this time, the ratio of the size of the terminal to be welded projecting from the resin molded product, the size of the welding terminal, and the size of the projection provided on the welding terminal is determined by the thickness t of the terminal to be welded.
_1: width w ₁ of the welding lug: projecting height h ₁ = about of the welding lug (3-4) :( 15-20) :( 30-60), the thickness of the welding lug t _2: the welding lug Width w ₂ : Length of welding terminal L ₂ :
Projection height h ₂ : Projection width w ₃ : Projection width w ₄ = about (2-3) :( 2
0-30): (70-100): (3-5): (7-1)
0): (1-3) is preferable.

As described above, the size of the terminal to be welded appropriately
By setting the size of the welding terminal and the size of the projection, when the terminal to be welded and the welding terminal are projection-welded, a welding nugget is formed between them and the quality and reliability of the product incorporating electronic components etc. itself Performance can be improved.

[0013] The projection welding method of the present invention is a projection welding method in which a copper welded terminal insert-molded in a resin molded product and a copper lead wire of an electronic component are overlapped and subjected to projection welding. The welding nugget is formed between the welded terminal and the welded terminal when the size of the welded terminal, the size of the lead wire, and the size of the projection projecting from the terminal are set to the predetermined size and the projection welding is performed. And

At this time, the ratio of the size of the terminal to be welded projecting from the resin molded product, the size of the projection provided on the terminal to be welded, and the size of the lead wire is determined by the thickness t _{3 of the} terminal to be welded: Terminal width w ₅ : Projection width w ₆ :
Lead wire diameter φ ₂ = about (2-3): (15-20):
(1-2): (6-8) is preferable.

As described above, the size of the terminal to be welded appropriately
By setting the size of the lead wire and the size of the projection, when the terminal to be welded and the lead wire are projection-welded, a welding nugget is formed between them and the quality and reliability of the product itself incorporating electronic components etc. Performance can be improved.

Further, the injection welding method of the present invention is a method of projecting welding a copper alloy welded terminal used near a light source and having a conductive surface treatment, and a copper alloy weld terminal not subjected to a conductive surface treatment. Then, on the side of the terminal to be welded, the plate thickness of this terminal to be welded is about 0.3-0.
Forming a projection in the shape of a kamaboko having a height of 6 times and a length of about 3 to 5 times the plate thickness, forming a pressurizing portion in a planar shape with chromium copper as a welding electrode in contact with a terminal to be welded. The welding electrode that comes into contact with the welding terminal is made of a high melting point material such as molybdenum, and the pressurized portion is formed in a planar shape. The projection of the terminal to be welded contacts the welding terminal, and a voltage is applied between the welding electrodes to perform projection welding. By doing so, a weld nugget is formed between the welded terminal and the welded terminal without damaging the conductive surface treatment of the portion of the terminal to be welded in contact with the welding electrode. At this time,
Preferably, the conductive surface treatment is electroless nickel plating, the welding electrode in contact with the terminal to be welded has a negative potential, and the welding electrode in contact with the welding terminal has a positive potential.

With the above-described structure, when a large current is applied while pressurizing with a welding electrode, a conductive surface treatment layer such as an electroless nickel plating layer is heated between the terminal to be welded and the welding terminal. As a result, the terminal to be welded and the terminal to be welded are locally melted and welded to form a welding nugget. On the other hand, a conductive surface treatment layer such as an electroless nickel plating layer on the pressurized side of a terminal to be welded pressed on a planar welding electrode has a large pressurized area, and heat generated at the welding electrode portion is applied to the welding electrode. It will remain undamaged for transmission.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a first embodiment shown in FIGS. 1 and 2 will be described. A terminal 1 made of copper, which is one terminal to be welded and joined, is insert-molded in a resin molded product 2. The terminal 1 to be welded has a flat plate shape and protrudes vertically upward from the resin molded product 2. The distal end of the terminal 1 to be welded is provided with a tapered portion 1a so as to be thinner as the distal end. The copper welding terminal 3, which is the other terminal to be welded and joined, is formed in a rectangular plate shape. An elliptical projection 4 is formed integrally with the welding terminal 3.

In the present invention, a resin molded product of the terminal 1 to be welded is provided.
2, the size of the welding terminal 3,
The ratio of the size of the projection 4 is determined by the thickness of the terminal 1 to be welded.
T ₁: Width w of terminal 1 to be welded₁: Projection height of terminal 1 to be welded
h₁= About (3-4): (15-20): (30-6)
0), thickness t of welding terminal 3_Two: Width w of welding terminal 3_Two:welding
Terminal 3 length L_Two: Height h of projection 4_Two:Professional
Vertical width w of injection 4_Three: Width of projection 4
w_Four= About (2-3): (20-30): (70-10)
0): (3-5): (7-10): (1-3)
I have.

As a specific example, w ₁ = 2 mm, h ₁
= 3 mm, t ₁ = 0.4 mm, w ₂ = 2 mm, L ₂ = 10
mm, t ₂ = 0.3 mm, w ₃ = 0.45 mm, w ₄ =
1.0 mm and h ₂ = 0.1 mm.

The welding electrodes 5 and 6 are electrode bodies 5a and 6a, respectively.
The pin portions 5b and 6b are press-fitted and integrated. In the case of this example, the electrode main bodies 5a and 6a are formed of chromium steel, and the pin portions 5b and 6b are formed of pure molybdenum. The terminal 1 to be welded and the welding terminal 3 are overlapped and pinched by the pin portions 5b and 6b of the welding electrodes 5 and 6, and pressurized at a constant pressure. After being pressurized by the welding electrodes 5 and 6, current flows from the welding electrodes 5 and 6, and current and stress concentrate on the projection 4, generating Joule heat to form a welding nugget and welding.

The welding voltage and current for forming a welding nugget when the terminal 1 to be welded, the welding terminal 3 and the projection 4 are formed to have the dimensions of the above specific example and the pressing force by the welding electrodes 5 and 6 is 50N. The time is as shown in the graph of FIG. In the graph of FIG. 2, the vertical axis indicates the voltage value (V), and the horizontal axis indicates the energizing time (msec). When the voltage value and the energizing time in the welding nugget formation region are satisfied, a welding nugget is formed.

As described above, in the above example, the welded terminal 1, the welding terminal 3, and the projection 4 are appropriate in size, so that a welding nugget can be formed even by projection welding of copper. In the conventional example, when the terminal 1 to be welded and the welding terminal 3 are projection-welded, a bonding interface is formed as shown in FIG. 8 and a welding nugget cannot be formed. However, in the present invention, a welding nugget is formed as shown in FIG. Could be welded.

Next, an example of the second embodiment shown in FIGS. 3 and 4 will be described. A terminal 7 made of copper, which is one terminal to be welded and joined, is insert-molded in a resin molded product 9. The terminal 7 to be welded has a flat plate shape and protrudes vertically upward from the resin molded product 9. The distal end of the welded terminal 7 is provided with a tapered portion 7a so as to be thinner as the distal end. A semi-cylindrical projection 8 is integrally provided on the tapered portion 7a at the tip of the terminal 7 to be welded. The lead wire 10 of the soft copper wire which is the other terminal to be welded and joined is a round wire, and is integrally led out from the electronic component 15.

In the present invention, the size of the portion of the terminal 7 to be projected from the resin molded article 9, the size of the projection 8, and the ratio of the lead wire 10 are determined by the thickness t _{3 of the} terminal to be welded: the thickness of the terminal to be welded. Width w ₅ : Projection width w ₆ :
Lead wire diameter φ ₂ = about (2-3): (15-20):
(1-2): (6-8).

As a specific example, w ₅ = 1.5 m
m, w ₆ = 0.2 mm, t ₃ = 0.4 mm, φ ₂ = 0.7
mm.

The welding electrodes 11 and 12 are respectively
It is formed by press-fitting the pin portions 11b and 12b into the a and 12a and integrating them. In the case of this example, the electrode body 1
1a and 12a are formed of chrome steel and have pin portions 11b and 1a.
2b is formed of pure molybdenum. The terminal 7 to be welded and the lead wire 10 are overlapped and the pin portions 5 of the welding electrodes 11 and 12 are overlapped.
b, 6b and pressurized at a constant pressure. After being pressurized by the welding electrodes 11 and 12, a current flows from the welding electrodes 11 and 12, and the current and stress concentrate on the projection 8, and a Joule heat is generated to form a welding nugget and weld.

In the case of the terminal 7 to be welded, the lead wire 10 and the projection 8 formed to the dimensions of the specific example described above, and when the pressing force by the welding electrodes 11 and 12 is 50 N, the welding voltage and the energization that can form a welding nugget are performed. The time is as shown in the graph of FIG. The graph of FIG. 4 shows the voltage value (V) on the vertical axis and the energizing time (msec) on the horizontal axis, and when the voltage value entering the welding nugget formation region and the energizing time are satisfied, a welding nugget is formed.

As described above, in the above example, the size of the terminal 7 to be welded, the lead wire 10 and the projection 8 are appropriate, so that a welding nugget can be formed by projection welding between copper. In the prior art, when the terminal 7 to be welded and the lead wire 10 were projection-welded, a bonding interface was formed as shown in FIG. 10 and a welding nugget could not be formed, but in the present invention, a welding nugget was formed as shown in FIG. Could be welded.

Next, an example of the third embodiment shown in FIGS. 11 and 12 will be described. The welding terminal 15 and the welding terminal 16 of the copper alloy used near the light source of the vehicle lighting are joined. The terminal 15 to be welded is a strip-shaped copper alloy material 15a.
Is formed by covering the entire surface with a conductive surface treatment layer 17. The copper alloy material 15a of the terminal 15 to be welded has a plate thickness of, for example, 0.3 mm. Conductive surface treatment layer 17
Is, for example, an electroless nickel plating layer 17a, for example, having a thickness of 5 μm. A projection 18 is provided on the terminal 15 to be welded. It is desirable that the projection 18 be formed on the copper alloy material 15a before the conductive surface treatment layer 17 is covered. This projection 18
Has a height of about 0.3 to 0.6 times the plate thickness of the terminal 15 to be welded, and is formed in a kamaboko shape having a length of about 3 to 5 times the plate thickness. The welding terminal 16 is a strip-shaped copper alloy material 16a.
The thickness is, for example, 0.4 mm.

Of the pair of welding electrodes 19, 20, the welding electrode 19 to be brought into contact with the terminal 15 to be welded is formed in a rectangular parallelepiped block shape from chromium copper and has a flat and wide contact surface. The width a of the welding electrode 19 is, for example, 8 mm and the thickness b
Is 7 mm, for example. Of the pair of welding electrodes 19 and 20, the welding electrode 20 to be brought into contact with the welding terminal 16 is formed by press-fitting the pin portion 20b into the electrode body 20a, and the contact surface at the tip of the pin portion 20b is made flat. is there.
The electrode body 20a is formed of chromium copper,
Ob is formed of a high melting point material such as molybdenum.
The width a of the electrode body 20a of the welding electrode 20 is, for example, 8 m.
m, and the thickness b is, for example, 7 mm.
Is, for example, 3 mm.

When projection welding is performed on the terminal 15 to be welded and the terminal 16 to be welded, the terminal 15 to be welded and the welding terminal 16 are overlapped so that the projection 18 of the terminal 15 to be welded comes into contact with the welding terminal 16. Electrode 1
A voltage is applied between the welding electrodes 19 and 20 by applying pressure between the welding electrodes 9 and 20. At this time, it is preferable to apply a voltage so that the welding electrode 19 has a negative potential and the welding electrode 20 has a positive potential. When a large current is applied while pressurizing with the welding electrodes 19 and 20, the conductive surface treatment layer 1 such as the electroless nickel plating layer 17a is provided between the terminal 15 to be welded and the welding terminal 16.
7 can be melted and removed by a local temperature rise due to resistance heating, and the welded terminal 15 and the welded terminal 16 can be locally melted and welded to form a weld nugget.
On the other hand, the terminal 1 to be welded pressurized by the flat welding electrode 19.
5, the conductive surface treatment layer 17 such as the electroless nickel plating layer 17a on the pressing side has a large pressing area,
The heat generated in the portion is transmitted to the welding electrode 19 and remains without being thermally damaged. FIG. 13 is a copy of a photograph of an enlarged cross section of a joint portion welded and joined by the method of the present invention, in which a weld nugget is formed and the electroless nickel plating layer 17a is melted and removed. In addition, the electroless nickel plating layer 17a of the terminal 15 to be pressurized by the welding electrode 19 has a large pressing area and heat generated in the electrode portion is transmitted to the welding electrode 19, so that the electroless nickel plating layer 17a remains without being thermally damaged. .

As described above, the welding voltage and energizing time for forming a welding nugget during projection welding are shown in FIG.
This is as shown in the graph of FIG. The graph of FIG. 12 shows the voltage value (V) on the vertical axis and the energizing time (msec) on the horizontal axis, and when the voltage value and the energizing time in the welding nugget formation region are satisfied, a welding nugget is formed.

The projection shape and the potential of the electrode for forming the welding nugget as described above can be confirmed by the following Table 1. At this time, the thickness of the copper alloy material 15a of the terminal 15 to be welded is 0.3 mm, and the thickness of the electroless nickel plating layer 17a is 5 μm. Welding terminal 16
Is 0.4 mm. The welding electrode 19 is made of chromium copper, the width a is 8 mm, and the thickness b is 7 mm. The welding electrode 20 is formed by press-fitting a pin portion 20b of molybdenum into an electrode body 20a of chromium copper.
Has a width a of 8 mm and a thickness b of 7 m.
m, and the diameter c of the pin portion 20b is 3 mm. The projection shape A is as shown in FIGS. 14 (a) and 14 (a) ', and the projection shape B is as shown in FIGS. 14 (b) and (b)'. 14 (c) and 14 (c) '
And the shape and dimensions shown in FIG.

[0035]

[Table 1]

In Table 1, ○ indicates that a weld nugget was formed, and X indicates that no weld nugget was formed. From this result, the projection 18 has a height of about 0.3 to 0.6 times the thickness of the terminal 15 to be welded and a length of about 3 to 5 times the thickness of the welded terminal 15. And
The welding electrode on the side of the terminal to be welded 15 is set to a negative potential,
It can be seen that a welding nugget is formed when the positive potential is set on the 6th side.

[0037]

According to the first aspect of the present invention, the size of the terminal to be welded projecting from the resin molded product, the size of the welding terminal and the size of the projection are set to a predetermined size and the projection is welded. Since a welding nugget is formed between a welding terminal and a welding terminal, a welding nugget is formed between the terminal to be welded and the welding terminal when projection welding is performed. It can improve the performance.

Further, according to the invention of claim 2 of the present invention, the size of the terminal to be welded, the size of the lead wire, and the size of the projection projecting from the resin molded product are set to a predetermined size and the size of the projection is reduced. Since a welding nugget is formed between the welding terminal and the welding terminal, a welding nugget is formed between the terminal to be welded and the lead wire when projection welding is performed, and the quality and reliability of the product itself incorporating the electronic components etc. It can improve the performance.

According to a fifth aspect of the present invention, the terminal to be welded has a height of about 0.3 to 0.6 times the thickness of the terminal to be welded, and the length is equal to the thickness of the plate. Forming a projection of approximately 3 to 5 times the shape of a kamaboko, forming the pressing part in a planar shape using chromium copper as the welding electrode that contacts the terminal to be welded,
The welding electrode in contact with the welding terminal is made of a material having a high melting point such as molybdenum, and the pressurized portion is formed in a flat shape. The projection of the terminal to be welded is brought into contact with the welding terminal, and a voltage is applied between the welding electrodes to perform projection welding. By forming a welding nugget between the welded terminal and the welded terminal without damaging the conductive surface treatment of the portion of the terminal to be welded in contact with the welding electrode, applying a large current while applying pressure with the welding electrode Between the terminal to be welded and the terminal to be welded, a conductive surface treatment layer such as an electroless nickel plating layer is melted and removed due to a local temperature rise due to resistance heating, and the terminal to be welded and the welding terminal are locally melted. The electroless nickel plating layer on the pressurized side of the terminal to be welded is pressed against the flat welding electrode. Such a conductive surface treatment layer has a large pressurized area, and heat generated at the welding electrode portion is transmitted to the welding electrode so that it remains without being thermally damaged. The reliability can be improved.

[Brief description of the drawings]

FIG. 1 shows an example of a first embodiment of the present invention, in which (a)
Is an exploded perspective view, (b) is a partially cutaway front view for explaining a welding state, and (c) is an enlarged view of the projection.

FIG. 2 is a graph for explaining an area where a welding nugget is formed.

3A and 3B show an example of the second embodiment, in which FIG. 3A is an exploded perspective view, and FIG. 3B is a partially cutaway front view for explaining a welding state.

FIG. 4 is a graph illustrating an area where a welding nugget is formed.

FIG. 5 is an explanatory diagram of resistance spot welding.

FIGS. 6A and 6B are explanatory diagrams of projection welding.

FIG. 7 is a copy of a cross-sectional cut photograph of a terminal to be welded and a welding terminal when a welding nugget is formed by projection welding.

FIG. 8 is a copy of a cross-sectional cut photograph of a terminal to be welded and a welding terminal when a welding nugget is not formed by projection welding.

FIG. 9 is a copy of a cross-sectional cut photograph of a terminal to be welded and a lead wire of an electronic component when a welding nugget is formed by projection welding.

FIG. 10 is a copy of a cross-sectional cut photograph of a terminal to be welded and a lead wire of an electronic component when a welding nugget is not formed by projection welding.

FIG. 11 shows an example of the third embodiment of the present invention,
(A) is an exploded front view of a main part in a welding state, (b) is a sectional view of a terminal to be welded and a welding terminal, (c) is a perspective view of one welding electrode, and (d) is a perspective view of the other welding electrode. It is a perspective view.

FIG. 12 is a graph illustrating an area where a welding nugget is formed.

FIG. 13 is a copy of a cross-sectional cut photograph of a terminal to be welded and a welding terminal when a welding nugget is formed by projection welding.

14 (a) and (a) 'are side and front views for explaining the shape and dimensions of the shape A in Table 1, and FIGS.
Side view and front view illustrating the shape and dimensions of shape B,
(C) and (c) 'are a side view and a front view for explaining the shape and dimensions of the shape C in Table 1.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 terminal to be welded 2 resin molding 3 welding terminal 4 projection 5 welding electrode 6 welding electrode 7 terminal to be welded 8 projection 9 resin molding 10 lead wire 11 welding electrode 12 welding electrode 15 welding terminal 16 welding terminal 17 conductive surface treatment 19 welding electrode 20 welding electrode

Claims (6)

[Claims] 1. A projection welding method in which a copper welded terminal and a copper welded terminal which are insert-molded in a resin molded product are overlapped and projection-welded, wherein the size of the welded terminal projecting from the resin molded product is: A projection welding method comprising forming a welding nugget between a terminal to be welded and a welding terminal when performing projection welding with the size of the welding terminal and the size of the projection being predetermined. 2. A projection welding method in which a copper welded terminal insert-molded in a resin molded product and a copper lead wire of an electronic component are overlapped and subjected to projection welding, wherein the terminal to be welded protrudes from the resin molded product. A projection welding method, wherein a welding nugget is formed between a terminal to be welded and a welding terminal when the size, the size of the lead wire, and the size of the projection are set to a predetermined size and projection welding is performed. 3. The ratio of the size of the terminal to be welded projecting from the resin molded product, the size of the welding terminal, and the size of the projection provided on the welding terminal is determined by the thickness t _{1 of the} terminal to be welded: the thickness of the terminal to be welded. Width w ₁ : Projection height h _{1 of the} terminal to be welded = about (3 to
4): (15 to 20): (30 to 60), thickness t _{2 of} welding terminal: width w _{2 of} welding terminal: length L _{2 of} welding terminal: height h _{2 of} projection: vertical width w of projection _3: next to the projection width w ₄ = about (2-3): 20-3
0): (70-100): (3-5): (7-10):
The projection welding method according to claim 1, wherein (1) to (3) is satisfied. 4. The size of the terminal to be welded projecting from the resin molded product, the size of the projection provided on the terminal to be welded,
The ratio of the size of the lead wire is the thickness t _{3 of the} terminal to be welded: the width w _{5 of the} terminal to be welded: the width w _{6 of the} projection: the wire diameter φ _{2 of the} lead wire = approximately (2 to 3): (15 to 20): (1 to
2): The projection welding method according to claim 2, wherein (6 to 8) is satisfied. 5. A method for projection welding a copper alloy welded terminal used in the vicinity of a light source and having a conductive surface treatment, and a copper alloy welded terminal not having a conductive surface treatment, comprising: The terminal has a height of about 0.3 to 0.6 times the thickness of the terminal to be welded, and has a length of about 3 times the thickness of the terminal.
Forming a projection of up to five times the shape of a kamaboko, forming the pressurized part in a planar shape using chromium copper as the welding electrode in contact with the terminal to be welded, and forming the welding electrode in contact with the welding terminal as a high melting point material such as molybdenum. Conductive surface treatment of the part in contact with the welding electrode of the terminal to be welded by forming the pressurized part in a planar shape, abutting the projection of the terminal to be welded against the welding terminal, applying a voltage between the welding electrodes and performing projection welding A projection welding method, wherein a welding nugget is formed between a terminal to be welded and a welding terminal without damaging the welding terminal. 6. The conductive surface treatment is performed by electroless nickel plating, a welding electrode in contact with the terminal to be welded is set to a negative potential, and a welding electrode in contact with the welding terminal is set to a positive potential. Projection welding method.