TW201903320A - Lead wire, lead manufacturing method, and vehicle light bulb - Google Patents

Abstract

The present invention provides a lead wire having a simple structure and capable of inhibiting the bent portion of the lead wire from opening, and also provides a lead wire manufacturing method and a vehicle light bulb. The embodiment of the lead wire includes: a core material which is in a line shape and contains iron and nickel; and a wrapping layer which contains nickel and covers the surface of the core material. The thickness of the wrapping layer is 1.0 <mu>m or more and 6.0 <mu>m or less.

Description

Lead wire, manufacturing method of lead wire, and vehicle light bulb

The present invention relates to a lead, a method for manufacturing the lead, and a light bulb for a vehicle.

There have been bulbs for vehicles including a bulb including glass and provided with a sealing portion at an end portion, a pair of leads, one end of which is provided inside the glass envelope, and the other end exposed from the sealing portion; and a filament ( filament), held inside the glass bulb, at the ends of a pair of leads. The end of the lead is bent, and the leg of the filament is held in a manner of sandwiching the leg of the filament. Here, the end portion of the glass bulb containing glass is heated, and the end portion of the heated glass bulb is pressed together with a pair of leads to form a sealing portion. Therefore, the pair of leads is formed of a material having a thermal expansion coefficient close to that of glass. Generally, the lead includes: a core material including a Fe-Ni alloy; a layer including copper to cover the core material; and a layer including nickel to cover the layer including copper. The thermal expansion coefficient of a lead including a core material containing an Fe-Ni alloy is close to that of glass. Therefore, it is possible to suppress a case where, when the pair of leads is sealed at the end of the glass bulb, the leads and the sealing portion are not completely in close contact with each other and a leak is generated.

However, the thermal expansion coefficient of the core material containing the Fe-Ni alloy, the thermal expansion coefficient of the layer containing copper, and the thermal expansion coefficient of the layer containing nickel are different. Therefore, when the light bulb for a vehicle is turned on, the bent portion of the lead wire may open due to the heat generated by the filament, which may cause the leg of the filament to detach from the lead wire, or the electrical connection between the lead and the leg of the filament may May be hindered.

Therefore, a lead has been proposed which joins the wire including the core material, the layer including copper and the layer including nickel, and the wire including nickel. As long as the wire material including the core material, the layer containing copper, and the layer containing nickel is sealed in the sealing portion, the occurrence of cracks can be suppressed. In addition, if the end portion of the wire including nickel is bent and the leg of the filament is sandwiched, it is possible to suppress the bent portion from being opened by the heat generated by the filament. However, in this case, the structure of the lead becomes complicated, and the manufacturing cost increases. Therefore, it is desired to develop a technology that has a simple structure and can suppress the opening of the bent portion of the lead. [Prior Art Literature]

[Patent Document] [Patent Document 1] Japanese Patent Laid-Open No. 9-45291

[Problem to be Solved by the Invention] The problem to be solved by the present invention is to provide a lead having a simple structure and capable of suppressing the opening of a bent portion of the lead, a method of manufacturing the lead, and a lamp for a vehicle. [Technical means to solve the problem]

The lead of the embodiment includes a core material that is linear and includes iron and nickel; and a cladding layer that includes nickel and covers a surface of the core material. The thickness of the coating layer is 1.0 μm or more and 6.0 μm or less.

[Effects of the Invention] According to the embodiments of the present invention, it is possible to provide a lead having a simple structure and capable of suppressing the bent portion of the lead from being stretched, a method for manufacturing the lead, and a vehicle light bulb.

Hereinafter, embodiments are illustrated with reference to the drawings. In each drawing, the same components are assigned the same reference numerals, and detailed descriptions are appropriately omitted. FIG. 1 is a schematic partial cross-sectional view illustrating a vehicle light bulb according to the present embodiment. FIG. 2 is a schematic diagram illustrating a bent portion of a lead. The vehicle light bulb 1 according to the present embodiment can be used for a brake light, a turn signal, a tail light, or the like provided in a vehicle such as a two-wheeled vehicle or a four-wheeled vehicle (an automobile). The vehicle light bulb 1 illustrated in FIG. 1 is a wedge base light bulb that does not include a socket. However, the use or form of the vehicle light bulb 1 is not limited to the exemplified uses or forms. The vehicle light bulb 1 according to the present embodiment can be applied to a vehicle light bulb including a pair of leads 6 holding a filament 4 inside a glass bulb 2.

As shown in FIG. 1, a vehicle bulb 1 is provided with a glass bulb 2, a sealing portion 3, a filament 4, a fixing member 5, and a lead 6. The glass bulb 2 is a cylindrical body having a hemispherical shape at one end. The shape of the glass bulb 2 is not limited to the exemplified ones. For example, the shape of the glass bulb 2 may be A-shape, G-shape, PS-shape, R-shape, T-shape, or a composite shape of these shapes, or it may include a plate-shaped body or a dish-shaped body. Flat-shaped etc. A sealing portion 3 is provided at the other end of the glass bulb 2. The glass bulb 2 is formed of a translucent material. Therefore, the glass bulb 2 becomes an airtight container having translucency.

The glass bulb 2 can be formed of glass such as soda lime glass, alkali glass, alkaline earth silicate glass (also referred to as lead-free glass, etc.). The physical properties of glass are, for example, a softening point of 665 ° C, an annealing point of 480 ° C, a strain point of 440 ° C, a thermal conductivity (100 ° C) of 1.1 (W / (m · K)), and a thermal expansion coefficient (30 ° C to 380 ° C). ) Is 5 × 10 ^-6 / ° C or higher (for example, 9.45 × 10 ^-6 / ° C). In this case, the glass bulb 2 only needs to have translucency. For example, the glass bulb 2 may be colorless and transparent, or may be colored. In addition, a coating film such as a colored film, a reflective film, a diffuser film, or a phosphor film, or unevenness may be provided on the surface or the inner surface of the glass bulb 2. The glass bulb 2 may be formed of a material including a scattering material, a phosphor, or the like.

The airtight container, that is, the pressure inside the glass bulb 2 is lower than the atmospheric pressure, or is filled with an inert gas. The enclosed inert gas can be, for example, xenon (Xe), krypton (Kr), argon (Ar), or a mixture of these gases. The enclosed inert gas can also contain nitrogen (N ₂ ) and the like. When the inert gas is enclosed, the pressure inside the glass bulb 2 can be about 0.5 MPa to 3.0 MPa. As long as the inert gas is enclosed, evaporation of the filament 4 can be suppressed, and the life of the vehicle light bulb 1 can be extended.

The sealing portion 3 has a rectangular parallelepiped shape. As described above, the sealing portion 3 seals one end portion of the glass bulb 2. For example, the end portion of the glass bulb 2 is heated, and the end portion of the heated glass bulb 2 is pressed together with the pair of leads 6, thereby forming the sealing portion 3. In this case, the sealing portion 3 is also formed of glass. An exhaust pipe 3 a is provided in the sealing portion 3. This exhaust pipe 3 a penetrates the inside of the sealing portion 3 and communicates with the inside of the glass bulb 2. The exhaust pipe 3 a is used when exhausting the inside of the glass bulb 2 or sealing an inert gas inside the glass bulb 2. An end portion on the outside air side of the exhaust pipe 3a is sealed. In addition, a convex hook portion or the like can be provided on the sealing portion 3, and this convex hook portion or the like is used when the vehicle light bulb 1 is held by a lamp provided in the vehicle.

The filament 4 includes a coil 4a and legs 4b provided at both ends of the coil 4a, respectively. The coil 4a is formed by winding a wire. The leg 4b extends linearly from the end of the coil 4a. The coil 4a is integrally formed with the leg 4b. The filament 4 (coil 4a, leg 4b) can be formed of the wire material containing tungsten (W) as a main component, for example.

The fixing member 5 is provided inside the glass bulb 2. The fixing member 5 holds a pair of leads 6. The fixing member 5 can be formed of glass, for example. For example, a member including heated glass is pressed together with a pair of leads 6, whereby the fixing member 5 can be formed. In this case, the glass bulb 2, the sealing portion 3, and the fixing member 5 can also be formed of the same material.

The lead 6 is linear. The cross-sectional size (diameter size) of the lead 6 can be, for example, 0.2 mm or more and 0.76 mm or less. As shown in FIG. 2, one end of the lead wire 6 is bent, and the leg 4 b of the filament 4 is held by sandwiching the leg 4 b of the filament 4. The other end of the lead 6 is exposed from the sealing portion 3. The portion of the lead 6 exposed from the sealing portion 3 becomes a terminal for connection to an external power source or the like.

Here, if the difference between the thermal expansion coefficient of the material of the lead 6 and the thermal expansion coefficient of glass, which is the material of the sealing portion 3, becomes large, the lead 6 and the sealing portion 3 may not completely adhere to each other and cracks may occur. Therefore, the lead 6 is formed of a material having a thermal expansion coefficient close to that of glass.

FIG. 3 is a schematic diagram illustrating a cross section of a lead of a comparative example. As shown in FIG. 3, the lead 16 includes a core material 16 a, a cladding layer 16 b, and a cladding layer 16 c. The core material 16a is linear. The cross-sectional shape of the core material 16a is, for example, circular. The core material 16a is formed of a material having a thermal expansion coefficient close to that of glass. The core material 16 a can be formed of, for example, an alloy containing iron (Fe) and nickel (Ni).

The cladding layer 16b covers the surface of the core material 16a. The cladding layer 16b includes, for example, copper (Cu). The cladding layer 16c covers the surface of the cladding layer 16b. The cladding layer 16b contains, for example, nickel. By providing the cladding layer 16c containing nickel, it is possible to prevent the cladding layer 16b containing copper from being oxidized when the lead 16 is sealed in the sealing portion 3. In addition, when the lead 16 is sealed in the sealing portion 3, the surface of the cladding layer 16c is oxidized to generate nickel oxide, and the nickel oxide is diffused into the glass. Therefore, the lead 16 and the sealing portion 3 can be brought into close contact.

Therefore, as long as the lead 16 is used, it is possible to prevent the lead 16 from coming into incomplete contact with the sealing portion 3 and causing cracks. However, since the materials of the core material 16a, the cladding layer 16b, and the cladding layer 16c are different, the thermal expansion coefficients of the core material 16a, the cladding layer 16b, and the cladding layer 16c are different. As described above, one end of the lead 16 is bent to hold the leg 4b of the filament 4 so as to sandwich the leg 4b of the filament 4. Therefore, if the thermal expansion coefficients of the core material 16a, the cladding layer 16b, and the cladding layer 16c are different, the bent portion of the lead 16 will be opened by the heat generated by the filament 4, and the leg 4b of the filament 4 may be detached. The lead 16 or the electrical connection between the lead 16 and the leg 4 b of the filament 4 may be hindered.

In this case, as long as the wire including nickel is bonded to one end portion of the lead 16 and the end portion of the wire including nickel is bent to sandwich the leg 4b of the filament 4, the bent portion can be suppressed from being caused by the filament 4. The heat is generated and spread out. However, in this case, the structure of the lead becomes complicated, and the manufacturing cost increases.

The inventors of the present invention have conducted research and found that as long as the number of types of coating layers is reduced, it is possible to suppress the bent portion 6c from being opened. FIG. 4 is a schematic diagram illustrating a cross section of a lead wire according to this embodiment. As shown in FIG. 4, the lead 6 includes a core material 6 a and a cladding layer 6 b. The core material 6a is linear. The cross-sectional shape of the core material 6a is, for example, circular. The core material 6a is formed of a material having a thermal expansion coefficient close to that of glass. The core material 6a contains, for example, iron and nickel. The core material 6a can be formed of, for example, an alloy containing iron and nickel. The core material 6a can be formed of, for example, Fe-Ni alloy, Fe-Ni-Cr alloy, Fe-Ni-Co alloy, and the like.

The cladding layer 6b covers the surface of the core material 6a. The cladding layer 6b contains nickel. As described above, as long as the surface of the lead 6 is covered with nickel, the nickel oxide generated when the lead 6 is sealed in the sealing portion 3 is diffused into the glass. Therefore, the lead 6 and the sealing portion 3 can be brought into close contact. In addition, since nickel is more difficult to oxidize than copper, it is possible to prevent the portion of the lead 6 exposed from the sealing portion 3 from being oxidized to cause a connection failure. Therefore, the cladding layer 6b becomes a layer containing nickel.

The lead 6 of this embodiment has fewer types of cladding layers than the lead 16 of the comparative example. Therefore, the influence of the thermal stress generated when the vehicle light bulb 1 is turned on and off can be reduced. As a result, it is easy to suppress the bent portion 6 c from being spread by the heat generated by the filament 4. In addition, the structure of the lead 6 can be simplified.

However, it is clear that if the cladding layer 16b containing copper is omitted, when the lead 6 is sealed in the sealing portion 3, bubbles are generated in the vicinity of the lead 6. If air bubbles are generated near the lead 6, a gap is easily generated between the lead 6 and the sealing portion 3, and cracks may occur. The bubble is considered to be a bubble formed when the gas adsorbed to the core material 6 a and the cladding layer 6 b is released when the lead 6 is sealed in the sealing portion 3. In the case of the lead 16 of the comparative example, since the cladding layer 16b containing copper is provided, it is possible to suppress the release of the gas adsorbed to the core material 16a to the outside. However, since the lead 6 of this embodiment is not provided with the cladding layer 16b containing copper, it is considered that bubbles are likely to be generated near the lead 6.

The inventors have conducted research and found that, as long as the core material 6a is formed and the cladding layer 6b having a predetermined thickness is formed, and then a predetermined heat treatment is performed, a lead 6 capable of suppressing generation of bubbles can be obtained. Next, a method for manufacturing the lead 6 according to this embodiment will be described. First, a core material 6a is formed. For example, a molten metal of the Fe-Ni alloy is generated, and an ingot of the Fe-Ni alloy is formed by a vacuum casting method or the like. Next, a rolled wire is formed from an ingot by a hot rolling method or the like, and cold-drawn and heat-treated are repeatedly performed on the rolled wire, for example, a core material 6a having a diameter of about 0.2 mm to 0.76 mm is formed.

Next, the core material 6a is subjected to a first heat treatment. For example, the core material 6a can be heat-treated using a heating furnace. In this case, the core material 6a can be heated to 700 ° C. or higher in an environment of nitrogen or hydrogen (H ₂ ), for example. As long as the core material 6a is heated to 700 ° C or higher, the gas or moisture adsorbed on the core material 6a can be removed. In this case, if the core material 6a is heated to 800 ° C or higher, the gas or moisture adsorbed on the core material 6a can be easily removed. In addition, if the core material 6a is heated to 900 ° C or higher, strain remaining in the core material 6a can be easily removed. As long as the strain remaining in the core material 6 a is removed, it is easy to obtain the core material 6 a having a desired thermal expansion coefficient.

The heating time can be appropriately adjusted in accordance with the diameter size and heating temperature of the core material 6a. For example, when the core material 6a has a diameter of about 0.76 mm and a heating temperature of about 900 ° C, the heating time can be set to about 20 to 200 seconds. In addition, nitrogen is more difficult to adsorb to the core material 6a than hydrogen. Therefore, if the core material 6a is heat-treated in a nitrogen environment, the amount of gas adsorbed to the core material 6a during cooling after heating can be suppressed. Therefore, it is more preferable to heat-process the core material 6a in a nitrogen environment.

Next, a cladding layer 6b is formed on the surface of the core material 6a. For example, the cladding layer 6b can be formed using a film forming method such as a plating method or a sputtering method. For example, a coating layer 6b containing nickel can be formed on the surface of the core material 6a using a plating method. Here, as described above, the end portion of the glass bulb 2 is heated, and the end portion of the heated glass bulb 2 is pressed together with the pair of leads 6 to form the sealing portion 3. Therefore, when the sealing portion 3 is formed, the lead 6 is heated.

In this case, if the thickness of the cladding layer 6b is too small, it is clear that iron contained in the core material 6a is easily deposited on the surface of the cladding layer 6b when the lead 6 is heated. Since iron is easily oxidized, if iron is deposited on the surface of the cladding layer 6b, the portion of the lead 6 exposed from the sealing portion 3 may be oxidized and a connection failure may occur. In addition, it is clear that if the thickness of the cladding layer 6b is too thick, the bent portion 6c of the lead 6 is easily opened. The reason why the bent portion 6c of the lead 6 is easily opened is not necessarily clear, but it is considered that if the thickness of the cladding layer 6b is too thick, the influence of thermal stress will increase. According to the findings obtained by the present inventors, the thickness of the coating layer 6b is preferably 1.0 μm or more and 6.0 μm or less. The details regarding the thickness of the cladding layer 6b will be described later.

Next, the core material 6a on which the coating layer 6b is formed on the surface is subjected to a second heat treatment. For example, the core material 6a on which the coating layer 6b is formed on the surface can be heat-treated using a heating furnace. For example, the core material 6a on which the coating layer 6b is formed on the surface can be heated to 700 ° C or higher in an environment of nitrogen or hydrogen. As long as the core material 6a on which the coating layer 6b is formed on the surface is heated to 700 ° C or higher, the gas or moisture adsorbed on the coating layer 6b can be removed. In addition, it is possible to remove gas or moisture adsorbed on the core material 6a. In this case, if the core material 6a on which the coating layer 6b is formed on the surface is heated to 800 ° C or higher, the gas or moisture adsorbed on the coating layer 6b is easily removed. In addition, if the core material 6a on which the coating layer 6b is formed on the surface is heated to 800 ° C or higher, it is easy to remove the gas or moisture adsorbed on the core material 6a. In addition, if the core material 6a on which the coating layer 6b is formed on the surface is heated to 900 ° C or higher, the strain remaining in the core material 6a is easily removed.

In this case, if the heating time is too long, the iron contained in the core material 6a is easily deposited on the surface of the cladding layer 6b. Therefore, the heating time of the second heat treatment is shorter than that of the first heat treatment. In this case, the heating time of the second heat treatment can be appropriately adjusted in accordance with the diameter size and heating temperature of the core material 6a on which the cladding layer 6b is formed on the surface. For example, when the core material 6a having the coating layer 6b formed on the surface has a diameter of about 0.3 mm and a heating temperature of about 900 ° C, the heating time can be set to about 20 to 30 seconds. In addition, nitrogen is more difficult to adsorb on the coating layer 6b than hydrogen. Therefore, if the core material 6a having the coating layer 6b formed on the surface thereof is heat-treated in a nitrogen environment, the amount of gas adsorbed on the coating layer 6b during cooling after heating can be suppressed. Therefore, it is more preferable to perform heat treatment on the core material 6a having the cladding layer 6b formed on the surface in a nitrogen environment. The lead 6 of this embodiment can be manufactured in the manner described above.

That is, the manufacturing method of the lead of this embodiment can include the following steps. A step of forming a linear core material 6 a containing iron and nickel. The core material 6a is subjected to a first heat treatment step in an environment of hydrogen or nitrogen. A step of forming a cladding layer 6b containing nickel on the surface of the core material 6a subjected to the first heat treatment. In a hydrogen or nitrogen environment, a second heat treatment step is performed on the core material 6 a on which the cladding layer 6 b is formed. In this case, in the step of forming the cladding layer 6b, a cladding layer 6b having a thickness of 1.0 μm or more and 6.0 μm or less is formed. The heating temperature in the first heat treatment can be set to 700 ° C or higher. The heating temperature in the second heat treatment can be set to 700 ° C or higher.

Furthermore, even after the second heat treatment, the core material 6a having the cladding layer 6b formed on the surface thereof can be made thinner. For example, the diameter of the core material 6a having the cladding layer 6b formed on the surface can be further reduced by cold drawing. When cold drawing is performed, strain is generated in the core material 6a on which the coating layer 6b is formed on the surface. Therefore, after the cold drawing, the core material 6 a on which the cladding layer 6 b is formed on the surface can be further subjected to heat treatment. The conditions of the heat treatment can be the same as those of the second heat treatment, for example.

Next, the first heat treatment, the second heat treatment, and the thickness of the cladding layer 6b will be further described. Tables 1 and 2 show cases related to comparative examples. That is, Tables 1 and 2 are cases where only the second heat treatment is performed and the first heat treatment is not performed. Table 1 shows the case where the second heat treatment was performed in a nitrogen environment. Table 2 shows the case where the second heat treatment was performed in a hydrogen environment. In the "bubble generation" of the evaluation item, the case where bubbles were not recognized by the naked eye was evaluated as "◎", and the cases where fine bubbles were recognized by the naked eye were evaluated, but there was no problem in the adhesion between the lead 6 and the sealing portion 3. It was "○", and when the bubble was recognized by the naked eye and the crack was generated, it evaluated as "x". In the "iron precipitation" of the evaluation item, the case where the surface of the coating layer 6b was not discolored was evaluated as "○", and the case where the surface of the coating layer 6b was discolored was evaluated as "X". In the "conduction" of the evaluation item, when the vehicle light bulb 1 is turned on and off a predetermined number of times with a predetermined lighting-off period, the case where there is no problem in the lighting state is evaluated as "○", and the case where the lighting cannot be performed is evaluated as "×". It should be noted that one cycle of turning on and off is set to turn on for three minutes and turn off for three minutes. In addition, the number of lighting-off times is set to 500 times.

[Table 1] [Table 2]

From Tables 1 and 2, it can be seen that if the thickness of the cladding layer 6b is 0.5 μm or less, iron contained in the core material 6a will be deposited on the surface of the cladding layer 6b. Since iron is easily oxidized, if the iron is deposited on the surface of the cladding layer 6b, the portion of the lead 6 exposed from the sealing portion 3 is oxidized to cause connection failure, and cannot be lit. On the other hand, if the thickness of the cladding layer 6b is 10.0 μm or more, the bent portion 6c of the lead 6 is easily opened, and the light cannot be turned on. In addition, if the first heat treatment is not performed, generation of bubbles cannot be suppressed.

Tables 3 to 6 show the cases where the first heat treatment and the second heat treatment were performed. Table 3 shows the cases where the first heat treatment and the second heat treatment were performed in a nitrogen environment. Table 4 shows the case where the first heat treatment was performed in a hydrogen environment and the second heat treatment was performed in a nitrogen environment. Table 5 shows the cases where the first heat treatment and the second heat treatment were performed in a hydrogen environment. Table 6 shows the case where the first heat treatment was performed in a nitrogen environment and the second heat treatment was performed in a hydrogen environment. The evaluation items and evaluation criteria are the same as those in Tables 1 and 2.

[table 3] [Table 4] [table 5] [TABLE 6]

As can be seen from Tables 3 to 6, if the thickness of the cladding layer 6b is 0.5 μm or less, the iron contained in the core material 6a is deposited on the surface of the cladding layer 6b. Since iron is easily oxidized, if the iron is deposited on the surface of the cladding layer 6b, the portion of the lead 6 exposed from the sealing portion 3 is oxidized to cause connection failure, and cannot be lit. On the other hand, if the thickness of the cladding layer 6b is 10.0 μm or more, the bent portion 6c of the lead 6 is easily opened, and the light cannot be turned on. Therefore, the thickness of the cladding layer 6b is preferably 1.0 μm or more and 6.0 μm or less.

In addition, if the first heat treatment and the second heat treatment are performed, it is possible to suppress the occurrence of bubbles in the sealed portion 3 and near the leads 6. As long as the generation of air bubbles can be suppressed, the generation of a gap between the lead 6 and the sealing portion 3 can be suppressed, and thus the occurrence of cracks can be suppressed.

In this case, nitrogen is more difficult to adsorb to the core material 6a and the cladding layer 6b than hydrogen. Therefore, the cases illustrated in Table 3 (when the first heat treatment and the second heat treatment are performed in a nitrogen environment) have the least generation of bubbles. The volume of the core material 6a is larger than that of the cladding layer 6b. Therefore, in the case exemplified in Table 6 (when the first heat treatment is performed in a nitrogen environment and the second heat treatment is performed in a hydrogen environment), Produces the second least. In addition, in the case exemplified in Table 4 (when the first heat treatment was performed in a hydrogen environment and the second heat treatment was performed in a nitrogen environment), the number of bubbles was the third smallest.

In addition, in the case illustrated in Table 5 (in the case where the first heat treatment and the second heat treatment are performed in a hydrogen environment), the generation of bubbles is slightly more than the cases illustrated in Tables 3, 4 and 6, but it can be reduced The generation of air bubbles.

FIG. 5 is a graph illustrating the amount of hydrogen released from the lead. "A" in FIG. 5 is a case where the lead 6 is not subjected to the first heat treatment and the second heat treatment. "B" is a case where the lead 6 is subjected to the first heat treatment and the second heat treatment in a nitrogen environment. The diameter of the lead 6 used for the measurement was 0.3 mm, the length was 10 mm, and the thickness of the cladding layer 6b was 2 μm.

For the measurement, a TDS (temperature rise separation analysis device) manufactured by Electronic Science Co., Ltd. and a model number: EMD-WA1000S / W were used. The measurement temperature range was 50 ° C to 1000 ° C, and the temperature increase rate was 60 ° C / min. The gas to be measured is hydrogen.

As can be seen from FIG. 5, if the first heat treatment and the second heat treatment are performed, gas generation can be significantly suppressed. Therefore, it is possible to suppress bubbles from being generated in the vicinity of the lead 6 inside the sealing portion 3. As long as the generation of air bubbles can be suppressed, the generation of a gap between the lead 6 and the sealing portion 3 can be suppressed, and thus the occurrence of cracks can be suppressed. In addition, in "A", it is considered that hydrogen generated near 380 ° C is mainly adsorbed on the coating layer 6b.

Table 7 is a table illustrating the relationship between the peak value of the hydrogen amount / the average value of the hydrogen amount and the generation of bubbles. The peak of the amount of hydrogen is the maximum value of the amount of hydrogen released in the range of 50 ° C to 1000 ° C. The average value of the amount of hydrogen is an average value of the amount of hydrogen released in a range of 50 ° C to 1000 ° C. In addition, in the evaluation item "Bubble generation", the case where bubbles were not recognized by the naked eye was evaluated as "◎", and fine bubbles were recognized by the naked eye, but there was no problem in the adhesion between the lead 6 and the sealing portion 3. The case was evaluated as "○", and the case where bubbles were recognized with the naked eye and cracks were evaluated as "X".

[TABLE 7] As can be seen from Table 7, as long as (the peak value of the hydrogen amount) / (the average value of the hydrogen amount) is 2.5 or less, generation of bubbles can be effectively suppressed. That is, when the amount of hydrogen released is measured until the lead 6 of this embodiment is heated to 50 ° C. to 1000 ° C., the (peak value of hydrogen amount) / (average value of hydrogen amount) is 2.5 or less.

As mentioned above, although several embodiment of this invention was illustrated, these embodiment are embodiment shown as an example, and it is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments or modifications thereof are included in the scope or spirit of the invention, and are included in the invention described in the patent application scope and the equivalent scope thereof. The above-mentioned embodiments can be implemented in combination with each other.

1‧‧‧vehicle bulb

2‧‧‧ glass bulb

3‧‧‧Sealing Department

3a‧‧‧Exhaust pipe

4‧‧‧ filament

4a‧‧‧coil

4b‧‧‧foot

5‧‧‧Fixed parts

6, 16‧‧‧ Lead

6a, 16a‧‧‧Core material

6b, 16b, 16c‧‧‧ cladding

6c‧‧‧ Bend

A‧‧‧If the lead 6 is not subjected to the first heat treatment and the second heat treatment

B‧‧‧Lead 6 subjected to the first heat treatment and the second heat treatment in a nitrogen environment

FIG. 1 is a schematic partial cross-sectional view illustrating a vehicle light bulb according to the present embodiment. FIG. 2 is a schematic diagram illustrating a bent portion of a lead. FIG. 3 is a schematic diagram illustrating a cross section of a lead of a comparative example. FIG. 4 is a schematic diagram illustrating a cross section of a lead wire according to this embodiment. FIG. 5 is a graph illustrating the amount of hydrogen released from the lead.

Claims (8)

A lead includes a core material that is linear and includes iron and nickel; and a cladding layer that contains nickel and covers the surface of the core material, and the thickness of the cladding layer is 1.0 μm or more and It is 6.0 μm or less. The lead wire according to item 1 of the scope of patent application, wherein when the hydrogen release amount is measured until the lead wire is heated to 50 ° C. to 1000 ° C., the peak value of the hydrogen amount / the average value of the hydrogen amount is 2.5 or less. A method for manufacturing a lead, which includes the following steps: forming a core material that is linear and includes iron and nickel; performing a first heat treatment on the core material in a hydrogen or nitrogen environment; A heat-treated core material has a coating layer comprising nickel on the surface thereof; and a second heat treatment is performed on the core material on which the coating layer is formed in an environment of hydrogen or nitrogen, and in the step of forming the coating layer To form the coating layer having a thickness of 1.0 μm or more and 6.0 μm or less. The method for manufacturing a lead according to item 3 of the scope of patent application, wherein a heating temperature of the first heat treatment is 700 ° C or higher. The method for manufacturing a lead according to item 3 or 4 of the scope of patent application, wherein the heating temperature in the second heat treatment is 700 ° C. or higher. The method for manufacturing a lead according to item 3 or 4 of the scope of patent application, wherein a heating time of the second heat treatment is shorter than a heating time of the first heat treatment. The method for manufacturing a lead according to item 5 of the scope of patent application, wherein a heating time of the second heat treatment is shorter than a heating time of the first heat treatment. A light bulb for a vehicle, comprising: a glass bulb; a pair of leads as described in item 1 or 2 of the scope of a patent application; a sealing portion that seals one end of the glass bulb and holds the glass bulb The pair of leads; and a filament, held inside the glass bulb at a bent portion of the pair of leads.