TWI740793B - Method for manufacturing lead terminal of chip type electrolytic capacitor and chip type electrolytic capacitor - Google Patents

Abstract

The present invention relates to a method for manufacturing a lead terminal, a wafer-type electrolytic capacitor, and a semi-finished product of a lead terminal. The solder wettability of the lead part of the lead terminal for a wafer-type electrolytic capacitor is suppressed from locally degrading, and the generation of metal powder is suppressed. A method for manufacturing a lead terminal (4). The lead terminal (4) has a strip-shaped lead part (41) and a terminal part (42) provided at one end thereof, and the lead terminal (4) is mounted to the lead terminal (4) via the terminal part A capacitor element (3) of a wafer-type electrolytic capacitor (1). The method includes a step of preparing a metal wire (411) with a polygonal cross-section provided with a coating layer (412) with good solder wettability on the outer periphery, and a step of preparing the metal wire ( 411) A step of forming a lead part (41) by pressing.

Description

Method for manufacturing lead terminal of chip type electrolytic capacitor and chip type electrolytic capacitor

The invention relates to a method for manufacturing a lead terminal for a wafer-type electrolytic capacitor, a wafer-type electrolytic capacitor and a semi-finished product of the lead terminal.

Generally, a lead terminal for a wafer-type electrolytic capacitor has a strip-shaped lead portion soldered to a circuit board and a terminal portion provided at one end thereof, and is mounted to the capacitor element of the wafer-type electrolytic capacitor via the terminal portion. The lead part is formed into a band shape by press working a metal wire rod with a circular cross section in the radial direction (Patent Document 1). In addition, in order to ensure the reliability of the soldering strength between the lead portion and the circuit board, it may be formed of a metal wire material provided with a coating layer (for example, a tin-plated layer) having good solder wettability on the outer periphery.

Prior art literature

Patent Document 1: Japanese Patent Laid-Open No. 11-26327

The problem to be solved by the invention

Conventionally, the cross-section of the metal wire forming the lead portion is circular. Therefore, when the metal wire is pressed, the thickness of the coating layer provided on the outer periphery may be locally thinned, which may impair solder wettability.

Fig. 7 is an explanatory diagram of a conventional pressing process of a lead part. As shown in (a) of FIG. 7, the cross section of the metal wire 511 forming the lead portion is circular, and a coating layer 512 is provided on the outer periphery. As shown in FIG. 7( b ), the metal wire 511 is sandwiched between the first press die 110 and the second press die 120 to form a strip-shaped lead portion. When the metal wire 511 is clamped, the cross-section deforms into an elliptical shape. However, at this time, since the coating layer 512 is soft, its thickness becomes the thinnest at the top and bottom of the center of the metal wire 511, and gradually changes to both sides. thick.

In this way, if the thickness of the cladding layer 512 is locally thinned, the solder wettability is greatly reduced in this portion, and the reliability of the soldering strength may be impaired. In addition, since the thickness of the coating layer 512 becomes thicker on both sides, a large amount of metal powder is generated on both sides of the metal wire 511, and there is also a problem that a short circuit of the circuit board is likely to occur and the capacitor characteristics are reduced.

The present invention was made in view of the above circumstances, and its object is to suppress the solder wettability of the lead portion of the lead terminal for a chip-type electrolytic capacitor from being locally lowered, and to suppress the generation of metal powder.

Technical means to solve the problem

In order to achieve the above-mentioned object, the first invention relates to a method of manufacturing a lead terminal 4 having a strip-shaped lead portion 41 and a terminal portion 42 provided at one end thereof, and the lead terminal 4 is attached to the lead terminal 4 via the terminal portion 42 The method for manufacturing the capacitor element 3 of the wafer-type electrolytic capacitor 1 includes: preparing a metal wire 411 with a polygonal cross section provided with a coating layer 412 with good solder wettability on the outer periphery; and pressing the metal wire 411 The process of forming the lead portion 41 by processing.

In addition, the second invention relates to a wafer-type electrolytic capacitor including the lead terminal 4 manufactured by the first invention.

In addition, the third invention relates to a semi-finished product 4'of a lead terminal 4. The lead terminal 4 has a strip-shaped lead portion 41 and a terminal portion 42 provided at one end thereof, and the lead terminal 4 is mounted to a wafer type via the terminal portion 42 In the capacitor element 3 of the electrolytic capacitor 1, the semi-finished product of the lead terminal has a metal wire 411 with a polygonal cross section extending from the terminal portion 42 and provided with a coating layer 412 with good solder wettability on the outer periphery. The metal wire 411 can be punched Processed and plastically deformed into the shape of the lead portion 41

The effect of the invention

According to the present invention, it is possible to prevent the solder wettability of the lead portion of the lead terminal for a wafer-type electrolytic capacitor from being locally lowered, and it is possible to suppress the generation of metal powder.

Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the chip-type electrolytic capacitor 1 of this embodiment includes a bottomed cylindrical container 2, a capacitor element 3 housed in the container 2, and a pair of lead terminals derived from the capacitor element 3. 4. A sealing member 5 that closes the opening of the container 2 and a seat plate 6 provided on the opening end side of the container 2. The container 2 is made of a thin metal plate, and the opening end is bent inward to fix and support the sealing member 5.

The lead terminal 4 has a strip-shaped lead portion 41 bent in an L-shape, and a terminal portion 42 is provided at one end thereof. The lead portion 41 is formed by pressing a metal wire material having a quadrilateral cross-section into a strip shape. In this embodiment, the metal wire is formed by cutting an elongated CP wire (copper-clad steel wire).

As shown in FIG. 3, a terminal portion 42 is provided at one end of the metal wire 411 to manufacture a semi-finished product 4'of the lead terminal, and the terminal portion 42 of the semi-finished product 4'is mounted on the electrode foil of the capacitor element 3, and the capacitor element 3 is incorporated in After the container 2 is formed, the metal wire 411 is press-processed into a strip shape to form the lead terminal 4.

In order to make the solder wettability good, the outer periphery of the metal wire 411 is provided with the coating layer 412 (refer FIG. 4) which consists of a tin plating layer. The terminal portion 42 is formed by pressing a rod-shaped member made of aluminum or the like, and has a flat portion 421 connected to the capacitor element 3 at one end of the terminal portion 42. To the other end of the terminal portion 42, one end of the metal wire 411 is connected by welding or the like, and the metal wire 411 extends from the terminal portion 42.

The sealing member 5 is formed of rubber or the like, and has a pair of through holes 51 through which the terminal portion 42 is inserted. The seat plate 6 is formed of an insulating material, and is fixed to the open end of the container 2 by bonding or the like.

The seat plate 6 has a pair of through holes 61 through which the lead portion 41 is inserted, and a pair of grooves 62 communicating with the through holes 61. After being inserted into the through hole 61, the pair of lead portions 41 are bent in directions away from each other and received in the groove 62.

Next, the manufacturing method of the lead terminal 4 is demonstrated.

The lead terminal 4 is manufactured through the following steps. First, an elongated CP wire having a polygonal cross-section provided with a coating layer 412 on the outer periphery is cut, and a metal wire 411 having a length corresponding to the lead portion 41 is prepared. Next, the terminal portion 42 is provided at one end of the metal wire 411. Then, the metal wire 411 is press-processed to form the lead portion 41.

In the process of forming the lead portion 41, as shown in FIG. 4(a), the metal wire 411 is clamped between the first punching die 110 and the second punching die 120, and plastically processed as shown in FIG. 4(b) Of the ribbon. In addition, after the metal wire 411 is processed into a strip shape, both sides of the metal wire 411 may be cut.

The cross-section of the metal wire 411 is quadrilateral, so the thickness of the coating layer 412 is not locally thinned on the upper and lower surfaces during press processing, and the thickness is approximately uniform over the entire length in the width direction.

Therefore, as compared with the metal wire 511 with a circular cross-section shown in FIG. 7, the thickness variation of the coating layer 412 after being processed into a band shape is reduced, and therefore, it is possible to suppress the solder wettability from being locally lowered. Thereby, the reliability of the soldering strength of the lead portion 41 to the circuit board is improved.

In addition, since the variation of the thickness of the coating layer 412 is reduced, the thickness of the coating layer 412 can be suppressed from becoming thicker on both sides, and metal powder is less likely to be generated. Therefore, it is possible to suppress the short circuit of the circuit board and the degradation of capacitor characteristics.

Next, the second embodiment of the present invention will be described.

As shown in FIG. 5( a ), in this embodiment, a plurality of groove-shaped recesses 130 are provided on the pressing surface 111 of the first pressing die 110 and the pressing surface 121 of the second pressing die 120. These recesses 130 are provided in parallel so as to extend in the axial direction of the metal wire 411 (the direction orthogonal to the paper surface in FIG. 5 ), and the cross-sections of the punching surfaces 111 and 121 are waveforms.

By providing such a plurality of recesses 130, when the metal wire 411 is clamped between the first press die 110 and the second press die 120, as shown in FIG. 5(b), the coating layer 412 follows the multiple recesses 130. The cross-section is deformed into a wave shape. Since a plurality of protrusions 412b extending in the axial direction of the metal wire 411 are formed, the dross 412a does not easily protrude to both sides of the metal wire 411.

On the other hand, as shown in FIG. 6, when the punching surface 111 of the first punching die 110 and the punching surface 121 of the second punching die 120 are not provided with a plurality of groove-shaped recesses 130, the same as the case of FIG. 5 In comparison, the dross 412a is easier to protrude to both sides of the metal wire 411, so the metal powder is easy to spill.

By providing the recesses 130 shown in FIG. 5 in the first press die 110 and the second press die 120, the metal powder is not easily scattered, so that the short circuit of the circuit board and the degradation of the capacitor characteristics can be further suppressed.

In addition, the present invention is not limited to the above-mentioned respective embodiments.

For example, the cross-sectional shape of the metal wire may be a polygon other than a quadrilateral.

In addition, the metal wire may be formed of materials other than the CP wire.

In addition, instead of the tin plating layer, a coating layer made of another material with good solder wettability may be provided on the outer periphery of the metal wire.

In addition, the step of pressing the metal wire material to form the lead portion may be performed before mounting the terminal portion to the electrode foil of the capacitor element. In this case, after the metal powder generated during the press processing of the lead part can be sufficiently removed from the lead terminal, the terminal part can be mounted on the electrode foil. Therefore, the metal powder does not easily adhere to the completed chip-type electrolytic capacitor, so it can Further suppress the short circuit of the circuit board and the degradation of the capacitor performance. In addition, when such a manufacturing method is applied to a case where a metal wire material whose cross-sectional shape is a shape other than a polygon is press-worked, the same effect can be obtained.

Moreover, the shape of the recessed part provided in the press surface of a 1st press die and the press surface of a 2nd press die may be a shape other than a groove shape, and the number of recessed parts may be singular.

In addition, the recessed portion may be provided only in one of the first press die and the second press die. In addition, in the case of pressing a metal wire with a cross-sectional shape other than a polygonal shape, the same can be obtained by providing recesses on at least one of the pressing surface of the first pressing die and the pressing surface of the second pressing die. Effect (the dross is not easy to protrude to both sides of the metal wire, and it is not easy to produce metal powder).

1 Chip-type electrolytic capacitors 2 Container 3 Capacitor components 4 Lead terminal 4'Semi-finished products of lead terminals 5 Sealing parts 6 Seat plate 41 Leading part 42 Terminal section 51 Through hole 61 Through hole 62 On the slot 110 First stamping die 111 Stamping surface 120 Second stamping die 121 Stamping surface 130 Recess 411 Metal wire 412 Coating layer 412a Dregs 412b Ribs 421 Flat section 511 Metal wire 512 Coating layer

Fig. 1 is a perspective view of a chip-type electrolytic capacitor with lead terminals according to the present invention.

Fig. 2 is a longitudinal cross-sectional view of the wafer-type electrolytic capacitor of Fig. 1.

Fig. 3 is a perspective view of a semi-finished product of the lead terminal of the present invention.

Fig. 4 is an explanatory diagram of the first embodiment of the lead terminal manufacturing method of the present invention.

Fig. 5 is an explanatory diagram of a second embodiment of the lead terminal manufacturing method of the present invention.

Fig. 6 is an explanatory diagram of a lead terminal manufacturing method of a comparative example.

Fig. 7 is an explanatory diagram of a conventional lead terminal manufacturing method.

110 First stamping die 120 Second stamping die 411 Metal wire 412 Coating layer

Claims (5)

A method for manufacturing a lead terminal, the lead terminal (4) has a strip-shaped lead part (41), The manufacturing method of the lead terminal is characterized in that it comprises: A process of preparing a metal wire (411) provided with a coating layer (412) with good solder wettability on the outer periphery; and A step of sandwiching the metal wire (411) between the first punching die (110) and the second punching die (120) to form the lead portion (41); At least one of the punching surface (111) of the first punching die (110) and the punching surface (121) of the second punching die (120) is provided with a recess (130); The coating layer (412) of the metal wire (411) is deformed along the recess (130). The method of manufacturing a lead terminal according to claim 1, wherein: The recess (130) has a groove shape extending in the axial direction of the metal wire (411). The method of manufacturing a lead terminal according to claim 2, characterized in that: A plurality of the recesses (130) are arranged in parallel. The method of manufacturing a lead terminal according to any one of claims 1 to 3, wherein: The cladding layer (412) is a tin-plated layer. A chip type electrolytic capacitor, which is characterized in that: A lead terminal (4) manufactured by the manufacturing method according to any one of claims 1 to 3 is provided.

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