JP6221909B2 - Manufacturing method of terminal fittings - Google Patents

Description

  The present invention relates to a terminal fitting and a manufacturing method thereof.

  Cu (copper) plates and Cu alloy plates are frequently used for terminal fittings used in connectors, but reduction of material costs and weight reduction of terminal fittings are strongly demanded. Therefore, there are terminal fittings manufactured using an Al (aluminum) plate and an Al alloy plate that are cheaper and lighter than Cu alloy or the like.

Al is oxidized in an air atmosphere, and a natural oxide film made of Al ₂ O ₃ which is a nonconductor is formed on the surface. Therefore, the terminal metal fitting made from the Al alloy plate has a natural oxide film with a large working force in the caulking process in order to form a good electrical connection between the electric wire and the barrel part for crimping the electric wire. Need to be destroyed. On the other hand, if the working force in the caulking process is excessively increased, there is a problem that the electric wire and the terminal fitting are damaged.

  In order to solve such a problem, there is a technique for forming an alumite film on the barrel portion (Patent Document 1). When a hard and brittle alumite film is formed on the barrel part, the alumite film is broken along with the deformation of the barrel part during caulking, and the metal Al inside the Al alloy plate can be easily exposed. Therefore, a good electrical connection can be formed between the barrel portion and the electric wire without excessively increasing the processing force, and damage to the electric wire and the terminal fitting can be suppressed.

JP2013-54835A

  However, if bending is performed on an Al alloy plate on which an alumite film is formed, cracks may occur in the bent portion as the alumite film is broken. The crack of the Al alloy plate is more likely to occur as the bending radius of the bent portion is smaller. Therefore, it is difficult to prevent the occurrence of cracks in the bent portion of the Al alloy plate on which the anodized film is formed, for example, when bending is performed with a small bending radius, such as bending to form a rectangular tube shape. It is.

  The present invention has been made in view of such a background, and intends to provide a terminal fitting that is inexpensive and easy to manufacture and has excellent quality, and a method for manufacturing the terminal fitting.

One aspect of the present invention is a terminal fitting having a main body formed by bending an Al alloy plate,
The main body portion has at least a barrel portion for crimping an electric wire, and a rectangular tube portion connected to the barrel portion,
An alumite layer is formed on the surface of the barrel part,
The terminal fitting is characterized in that the alumite layer is not formed on the surface of the rectangular tube portion.

In another aspect of the present invention, the entire surface of the strip-shaped Al alloy plate is anodized to form an alumite layer,
An alkali solution is brought into contact with one end side in the width direction of the Al alloy plate to form a front region from which the anodized layer is removed, and the anodized layer remains on the other end side in the width direction of the Al alloy plate. Formed rear region,
The aluminum alloy plate is pressed to form a barrel portion for crimping an electric wire in the rear region, and a square tube portion connected to the barrel portion is formed in the front region. In the manufacturing method.

  The terminal fitting has the alumite layer on the surface of the barrel portion. Therefore, the alumite layer can be destroyed by caulking when the end portion of the electric wire is crimped to the barrel portion, and the metal Al can be easily exposed. As a result, a good electrical connection can be formed between the terminal fitting and the electric wire.

  Further, the alumite layer is not formed on the surface of the rectangular tube portion. Therefore, the workability in the bending process for forming the rectangular tube part is good, and the Al alloy plate can be prevented from cracking in the bent part formed by the bending process.

  Further, according to the method of manufacturing the terminal fitting, after forming the alumite layer on the entire surface of the Al alloy plate having a strip shape, the barrel portion is formed by contacting an alkali solution with a part of the alumite layer. The alumite layer can be left only in the rear region. Thereby, a manufacturing process can be simplified and processing cost can be reduced. Moreover, the said manufacturing method can perform continuously each process of formation of an alumite layer, removal of an alumite layer, and press work by using the said Al alloy board which exhibits strip | belt shape. Therefore, the manufacturing method has excellent productivity.

  As described above, the terminal fitting is inexpensive and easy to manufacture and has excellent quality.

The perspective view of the terminal metal fitting comprised as a male type terminal in Example 1. FIG. The top view of the Al alloy board in which the front region and the back region in Example 1 were formed. The top view of the Al alloy board in which the front region, the rear region, and the contact region were formed in Example 1. The top view of the terminal intermediate body which stamps the Al alloy plate of FIG. The perspective view of the terminal metal fitting comprised as a female-type terminal in Example 2. FIG. The VI-VI line partial arrow directional cross-sectional view of FIG. The top view of the Al alloy board in which the front region and the back region in Example 2 were formed. The top view of the terminal intermediate body which stamps the Al alloy plate of FIG.

  The terminal fitting can be configured as a known male terminal or female terminal. Moreover, as an Al alloy plate which comprises a terminal metal fitting, the board | plate material which consists of a well-known Al alloy can be used. From the viewpoints of strength, workability and corrosion resistance, 3000 series Al alloys, 5000 series Al alloys and 6000 series Al alloys can be suitably used.

  An alumite layer is not formed on the surface of the rectangular tube portion in the main body portion. That is, the rectangular tube portion can be, for example, an aspect in which the Al alloy plate is exposed on the surface, an aspect in which a metal plating layer described later exists on the surface, or the like. Thus, by forming the rectangular tube portion from a material that is softer than alumite and has excellent ductility, the occurrence of cracks in the rectangular tube portion can be prevented.

  It is preferable that the film thickness of the alumite layer provided in a barrel part is 1-10 micrometers. In this case, since the alumite layer can be reliably destroyed when the barrel portion is caulked, a good electrical connection can be reliably formed between the electric wire and the terminal fitting.

  When the film thickness of the alumite layer is less than 1 μm, the destruction of the alumite layer due to the caulking process becomes insufficient, and the contact between the metal Al of the Al alloy plate and the electric wire may be insufficient. As a result, the electrical resistance between the Al alloy plate and the electric wire may increase. In this case, the effect of improving the corrosion resistance by the alumite layer is insufficient, and the terminal fitting may be easily corroded.

  On the other hand, when the film thickness of the anodized layer exceeds 10 μm, the contact between the metal Al and the electric wire is hindered by the broken anodized layer, and the electric contact between the metal Al and the electric wire may be insufficient. As a result, the electrical resistance between the Al alloy plate and the electric wire may increase. Moreover, when the method of removing an alumite layer by contact with an alkaline solution is adopted in the production method described later, the film thickness of the alumite layer is excessively large, and therefore the time for contacting with the alkaline solution may be increased. As a result, the productivity of the terminal fitting may be reduced.

  The terminal fitting may have a metal plating layer made of any of Sn (tin), Au (gold), Ag (silver), or In (indium) at a portion that becomes an electrical contact with the counterpart terminal. In this case, the contact resistance when connecting the counterpart terminal can be further reduced. From the viewpoint of material cost and connection reliability, it is more preferable to use an Sn plating layer as the metal plating layer.

  When the metal plating layer is a Sn plating layer, the Sn plating layer preferably has a thickness of 1 to 3 μm. In this case, the contact resistance with the counterpart terminal can be sufficiently reduced. When the film thickness of the Sn plating layer is less than 1 μm, the effect of reducing contact resistance may be insufficient. On the other hand, if the thickness of the Sn plating layer exceeds 3 μm, the presence of the soft Sn plating layer may increase the friction coefficient when sliding with the counterpart terminal, and as a result, when inserting the terminal fitting. There is a risk that the insertion force required for the operation will increase.

  The metal plating layer can be formed by a conventionally known plating method. In addition, before the plating process, a natural oxide film removal by acid cleaning or the like and a pretreatment such as a zincate process are usually performed. Conventionally known conditions can also be used for these pretreatments.

  The metal plating layer may be laminated directly on the Al alloy plate, or an intermediate layer may be provided between the Al alloy plate and the metal plating layer. For the intermediate layer, a metal having an effect of improving the adhesion between the Al alloy plate and the metal plating layer can be used. For example, when the metal plating layer is a Sn plating layer, it is preferable to use a Ni (nickel) plating layer having a thickness of 0.1 to 0.5 μm as the intermediate layer. When the film thickness of the Ni plating layer is less than 0.1 μm, the adhesion between the Al alloy plate and the Sn plating layer becomes insufficient, and the durability of the terminal fitting may be reduced. Moreover, when the film thickness of Ni plating layer exceeds 0.5 micrometer, there exists a possibility that the workability in the preparation process of a terminal metal fitting may become low by presence of a comparatively hard Ni plating layer.

  Next, the manufacturing method of a terminal metal fitting is demonstrated. First, an Al alloy plate having a strip shape is prepared. From the viewpoint of manufacturing cost reduction, a coil material having a strip shape is often used as an Al alloy plate.

  The Al alloy plate is subjected to pretreatment such as degreasing and natural oxide film removal, and then anodized to form an alumite layer on the entire surface. For the anodizing treatment, it is preferable to use an acidic electrolytic solution such as an aqueous solution containing sulfuric acid. In this case, the alumite layer can be removed more efficiently by contact with an alkaline solution. As a result, the productivity of the terminal fitting can be further improved.

  After the alumite layer is formed on the entire surface, an alkaline solution is brought into contact with a part of the Al alloy plate to form a front region from which the alumite layer has been removed. The portion where the alkaline solution did not contact becomes the rear region where the alumite layer is left. Usually, the boundary between the front region and the rear region can be formed with sufficient positional accuracy by immersing only the portion to be the front region in the alkaline solution. In order to form the boundary more precisely, the alkaline solution may be brought into contact with the alumite layer in a state where only the rear region is covered with a masking material. As the alkaline solution, for example, a general plating pretreatment agent such as an aqueous solution containing sodium hydroxide can be used.

  After removing the alumite layer in the front region, if necessary, at least a part of the front region may be plated to form a contact region having the metal plating layer. For example, when the terminal fitting is configured as a male terminal, the tab portion serving as an electrical contact with the counterpart terminal is connected to the square tube portion, and the square tube portion and the tab portion are formed from the same Al alloy plate. can do. When the terminal fitting is configured as a female terminal, an electrical contact with the counterpart terminal may be provided on the inner wall surface of the rectangular tube portion. As described above, when the square tube portion and the portion to be an electrical contact can be manufactured from the same Al alloy plate, by forming a contact region in the Al alloy plate in advance, in the press working step, the square tube portion and Simultaneously with the formation of the barrel portion, the tab portion and the like can be formed with the metal plating layer. As a result, the manufacturing process of the terminal fitting can be further simplified, and the productivity of the terminal fitting can be further improved.

  The manufacturing method described above is configured to press the band-shaped Al alloy plate after forming the front region and the rear region. Thus, by completing the wet process such as the anodizing treatment and the removal of the alumite layer, and the plating treatment performed as necessary before the press working, compared with the case where the wet process is performed after the press working. The manufacturing process can be greatly simplified, and the cost can be reduced more easily.

  In addition to the manufacturing method described above, the terminal fitting can take various forms. For example, in order to form an alumite layer only in the rear region, it is possible to use a method in which a part of the Al alloy plate is covered with a masking material and anodization is performed with only the rear region exposed.

  Further, as a method of removing the alumite layer, mechanical polishing such as blasting or paper polishing may be used instead of the method of contacting with an alkaline solution. In this case, it is preferable to use a masking material in order to precisely form the boundary between the front region and the rear region.

  It is also possible to perform press working prior to the wet process described above.

Example 1
Examples of the terminal fitting will be described with reference to FIGS. As shown in FIGS. 1 to 4, the terminal fitting 1 has a main body 11 formed by bending an Al alloy plate 6. The main body portion 11 includes at least a barrel portion 2 that crimps an electric wire and a rectangular tube portion 4 that is continuous with the barrel portion 2. The alumite layer 20 is formed on the surface of the barrel portion 2, and the alumite layer 20 is not formed on the surface of the rectangular tube portion 4. The details will be described below.

  The terminal fitting 1 is configured as a male terminal. The main body portion 11 includes a barrel portion 2 for connecting electric wires, a rectangular tube portion 4 connected to the barrel portion 2, and a tab portion 3 extending from the rectangular tube portion 4. Moreover, the tab part 3 has the Sn plating layer 30 on the surface.

  As shown in FIG. 1, the main body portion 11 has a substantially rod shape, and the tab portion 3, the rectangular tube portion 4, and the barrel portion 2 are arranged in a line. In addition, in this example, the barrel part 2 side in the longitudinal direction of the main body part 11 may be referred to as the rear, and the tab part 3 side may be referred to as the front. The description in the front-rear direction is for convenience and has nothing to do with the actual orientation when the terminal fitting 1 is used.

  The rectangular tube portion 4 has a substantially rectangular tube shape extending in the longitudinal direction of the main body portion 11. The tab portion 3 is connected to the front opening end 41 of the rectangular tube portion 4, and the barrel portion 2 is connected to the rear opening end 42. Further, the alumite layer 20 is not formed on the surface of the rectangular tube portion 4, and the Al alloy plate 6 is exposed.

  The tab portion 3 extends forward with the opening end 41 in front of the rectangular tube portion 4 as a base end, and has a flat cross section perpendicular to the front-rear direction.

  As shown in FIG. 1, the barrel portion 2 includes a wire barrel portion 21 that crimps and electrically connects a conductor exposed from the end portion of the electric wire, and an insulation barrel portion 22 that crimps the insulating coating portion of the electric wire. have.

  As shown in FIG. 1, the wire barrel portion 21 and the insulation barrel portion 22 are formed by bending an Al alloy plate 6, and a cross section perpendicular to the longitudinal direction of the main body portion 11 is substantially U-shaped. Yes. In addition, since the bending process for forming the wire barrel part 21 and the insulation barrel part 22 has a larger bending radius than the bending process for forming the square tube part 4, the Al alloy plate 6 accompanying the bending process is used. It is difficult for cracks to occur.

  An electric wire (not shown) connected to the barrel portion 2 has a conductor in contact with the wire barrel portion 21 and a bottom surface 23 (see FIG. 1) of the barrel portion 2 with the insulation coating portion in contact with the insulation barrel portion 22. See). By performing the caulking process (arrow F in FIG. 1) in this state, the anodized layer 20 provided on the surface of the wire barrel portion 21 is broken, and between the metal Al of the Al alloy plate 6 and the conductor of the electric wire. An electrical connection is formed.

  As shown in FIG. 1, the bottom surface 23 of the wire barrel portion 21 is provided with a serration portion 24 that protrudes from the periphery. The serration portion 24 has an action of concentrating pressure on a contact portion between the serration portion 24 and the conductor when connecting the conductors. As a result, the natural oxide film present on the surface of the conductor can be easily broken, and a good electrical connection between the wire barrel portion 21 and the conductor can be more easily formed.

  Next, an example of the manufacturing method of the terminal metal fitting 1 is demonstrated. First, an Al alloy plate 6 having a strip shape is prepared, and processing oil is degreased. Thereafter, the entire surface of the Al alloy plate 6 is anodized to form the alumite layer 20, and then an alkali solution is brought into contact with one end 601 side in the width direction of the Al alloy plate 6. As a result, as shown in FIG. 2, the front region 61 from which the anodized layer 20 is removed is formed, and the rear region 62 from which the anodized layer 20 is left on the other end 602 side in the width direction of the Al alloy plate 6. Form.

  In this example, after the front region 61 and the rear region 62 are formed, at least a part of the front region 61 is plated to form the contact region 63 having the Sn plating layer 30 as shown in FIG. To do. The contact region 63 can be formed, for example, by immersing only a part of the Al alloy plate 6 on the one end 601 side in the front region 61 in an Sn plating bath and performing an electroplating process. The contact region 63 can also be formed by performing an electroplating process in a state where the region other than the contact region 63 is covered with a masking material.

  After forming the front region 61, the rear region 62, and the contact region 63, the Al alloy plate 6 is punched to form the terminal intermediate 60 shown in FIG. The terminal intermediate body 60 includes a plurality of terminal portions T corresponding to the main body portion 11 and a carrier portion C connecting the plurality of terminal portions T. The contact region 63 in the terminal portion T becomes the tab portion 3 by a bending process performed following the punching process. Similarly, the region where the Al alloy plate 6 is exposed in the front region 61 becomes the square tube portion 4 by bending. The rear region 62 becomes the barrel portion 2 by bending. Further, the carrier portion C is provided in the rear region 62 and is configured to be continuous with the barrel portion 2 after being bent.

  Then, after bending the terminal part T, the terminal part 1 can be obtained by separating the carrier part C.

  Next, the function and effect of this example will be described. The terminal fitting 1 has an alumite layer 20 only on the surface of the barrel portion 2. Therefore, a good electrical connection can be formed between the terminal fitting 1 and the electric wire by caulking when the end portion of the electric wire is crimped to the barrel portion 2.

  Further, the Al alloy plate 6 is exposed on the surface of the rectangular tube portion 4, and the Sn plating layer 30 exists on the surface of the tab portion 3. Thus, since the alumite layer 20 does not exist on the surfaces of the square tube portion 4 and the tab portion 3, workability when forming the square tube portion 4 and the tab portion 3 by bending the front region 61. Is good. Therefore, for example, cracks at a portion where the bending radius is small, such as a corner 400 (see FIG. 1) existing in the rectangular tube portion 4 and a 180 ° bent portion 300 (see FIG. 1) existing in the tab portion 3 are obtained. Occurrence can be suppressed.

  Moreover, since the Sn plating layer 30 is formed on the surface of the tab portion 3, the contact resistance when connecting the counterpart terminal can be reduced. Furthermore, by using inexpensive Sn, it is possible to easily reduce the cost while ensuring connection reliability.

  As described above, the terminal fitting 1 is inexpensive and easy to manufacture, and has excellent quality.

  In addition, in this example, although the example in which the Sn plating layer 30 exists only in the tab part 3 was shown, you may provide the Sn plating layer 30 in the surface of the square cylinder part 4 further.

(Example 2)
This example is an example of the terminal fitting 10 configured as a female terminal. As shown in FIG. 5, the main body portion 12 of the terminal fitting 10 has a square tube portion 4 and a barrel portion 2. Further, as shown in FIG. 6, the rectangular tube portion 4 has an elastic piece portion 5 that presses the mating terminal inserted into the rectangular tube portion 4 toward the top wall portion 44. Moreover, the elastic piece part 5 has the Sn plating layer 30 on the surface.

  As shown in FIG. 5, the main body portion 12 has a substantially rod shape, and the rectangular tube portion 4 and the barrel portion 2 are arranged in a line. In addition, in this example, the barrel part 2 side in the longitudinal direction of the main body part 12 may be referred to as the rear, and the square tube part 4 side may be referred to as the front. The description in the front-rear direction is for convenience, and has nothing to do with the actual orientation when using the main body 12.

  The rectangular tube portion 4 has a substantially rectangular tube shape extending in the longitudinal direction of the main body portion 12. The opening end 41 in front of the rectangular tube portion 4 is open so that the tab portion 3 of the male terminal (terminal fitting 1) can be inserted. Further, the barrel portion 2 is connected to the rear opening end 42. An alumite layer 20 is not formed on the surface of the rectangular tube portion 4, and the Al alloy plate 6 is exposed.

  The elastic piece portion 5 is formed of an Al alloy plate different from the Al alloy plate 6 constituting the main body portion 12, and as shown in FIG. 6, via the top wall portion 44 of the square tube portion 4 and a gap. Face to face. The elastic piece portion 5 is extended so as to approach the top wall portion 44 toward the front, with the rear end portion 52 as the base end. Moreover, the elastic piece part 5 has the bending part 53 between the front edge part 51 and the rear edge part 52, and the front side rather than the bending part 53 leaves | separates from the top wall part 44 as it goes ahead. It is so extended.

  The bent portion 53 is formed with an embossed portion 54 that protrudes toward the top wall portion 44 so as to have a substantially spherical shape. The embossed portion 54 presses the tab portion 3 upward while being in contact with the tab portion 3 when the tab portion 3 of the male terminal is inserted into the rectangular tube portion 4. Further, in a state where the embossed portion 54 and the tab portion 3 are in contact, the Sn plating layer 30 existing on the surface of the embossed portion 54 is pressed against the Sn plating layer 30 existing on the surface of the tab portion 3, and between them An electrical connection is formed.

  A positioning hole 521 penetratingly formed in the thickness direction is provided at the rear end 52 of the elastic piece portion 5, and a positioning convex portion 401 erected on the rectangular tube portion 4 is inserted into the positioning hole 521. Yes. Further, the elastic piece portion 5 is fixed to the square tube portion 4 by laser welding in the vicinity of the positioning hole 521.

  Next, an example of a method for manufacturing the terminal fitting 10 will be described. The main body 12 can be manufactured by the same procedure as in the first embodiment. That is, after anodizing the Al alloy plate 6 having a strip shape, an alkaline solution is contacted to form a front region 61 and a rear region 62 as shown in FIG. Next, the Al alloy plate 6 is punched to form a terminal intermediate 600 shown in FIG. The terminal intermediate body 600 has a plurality of terminal portions T corresponding to the main body portion 12 and a carrier portion C connecting the plurality of terminal portions T. The front region 61 in the terminal portion T is a region that becomes the rectangular tube portion 4, and the rear region 62 is a region that becomes the barrel portion 2. Further, the carrier portion C is provided in the rear region 62 and is configured to be continuous with the barrel portion 2 after being bent.

  Although not shown in the drawing, the elastic piece 5 is made of an Al alloy plate different from the Al alloy plate 6 described above. Specifically, an Al alloy plate is prepared, and Sn plating treatment and press working are sequentially performed on the Al alloy plate. Thereby, the elastic piece part 5 which has the Sn plating layer 30 on the surface is produced separately from the terminal intermediate body 600.

  The terminal intermediate body 600 and the elastic piece portion 5 obtained separately as described above are assembled as follows. First, after the positioning convex portion 401 is formed on the terminal portion T, the positioning convex portion 401 is inserted into the positioning hole 521 of the elastic piece portion 5. Thereby, the elastic piece part 5 is arrange | positioned in the predetermined position on the terminal part T. FIG.

  Next, the terminal portion T is bent to form the rectangular tube portion 4 and the barrel portion 2. And the elastic piece part 5 is fixed in the square cylinder part 4 by performing the crimping process and laser welding of the positioning convex part 401 with the bending process of the terminal part T. FIG.

  Then, the terminal fitting 10 can be obtained by separating the carrier part C. Others are the same as in the first embodiment. Of the reference numerals used in FIGS. 5 to 8, the same reference numerals as those used in the first embodiment represent the same components as in the first embodiment.

  In the terminal fitting 10 of this example, the Al alloy plate 6 is exposed on the surface of the rectangular tube portion 4. Therefore, as in the first embodiment, the occurrence of cracks in the corner portion 400 (see FIG. 5) existing in the square tube portion 4 can be suppressed, and it is inexpensive, easy to manufacture, and has excellent quality.

  Further, the elastic piece portion 5 is formed of an Al alloy plate different from the main body portion 12. Therefore, an Al alloy having a spring limit value higher than that of the main body portion 12 can be used for the elastic piece portion 5, and the pressing force when pressing the counterpart terminal can be sufficiently increased. As a result, the contact resistance can be further reduced, and the electrical connection with the counterpart terminal can be maintained for a longer period.

  In addition, in this example, although the Sn plating layer 30 was provided on the elastic piece part 5 and the structure which makes the embossing part 54 an electrical contact with an other party terminal was shown, it is also possible to provide an electrical contact in the square cylinder part 4. It is. Such a configuration can be realized, for example, by providing the Sn plating layer 30 by plating the entire front region 61 (see FIG. 7) of the Al alloy plate 6. In this case, the top wall portion 44 of the rectangular tube portion 4 serves as an electrical contact with the counterpart terminal.

  The manufacturing method shown in Example 1 and Example 2 is configured to press the band-shaped Al alloy plate 6 after forming the front region 61 and the rear region 62. Therefore, as described above, the manufacturing process can be greatly simplified and the cost can be reduced more easily than when the wet process is performed after press working.

  Note that the above-described manufacturing method is an example, and the configuration may be changed as appropriate without departing from the gist of the manufacturing method.

DESCRIPTION OF SYMBOLS 1, 10 Terminal metal fittings 11, 12 Body part 2 Barrel part 20 Anodized layer 4 Square cylinder part 6 Al alloy plate

Claims (3)

Anodizing is performed on the entire surface of the Al alloy plate having a strip shape to form an alumite layer,
An alkali solution is brought into contact with one end side in the width direction of the Al alloy plate to form a front region from which the anodized layer is removed, and the anodized layer remains on the other end side in the width direction of the Al alloy plate. Formed rear region,
The aluminum alloy plate is pressed to form a barrel portion for crimping an electric wire in the rear region, and a square tube portion connected to the barrel portion is formed in the front region. Production method. 2. The method for manufacturing a terminal fitting according to claim 1 , wherein the alumite layer is formed by an anodic oxidation treatment using an acidic electrolytic solution. And plated on at least a portion of said front region, Sn, Au, according to claim 1 or 2, characterized in that to form a contact area with Ag or become more metal plating layer or an In Manufacturing method for terminal fittings.

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