JP2002203745A - Chip type solid-state electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the generation of solder fillets due to the creeping-up of a molten soldering material along a lead terminal, in a chip type solid-state electrolytic capacitor with a pair of lead terminals bent like crab legs. SOLUTION: In the chip type solid-state electrolytic capacitor 10, a resin packaging material 4 is formed around a capacitor element 2 formed of a sintered material of valve action metal powder. The pair of lead terminals 3 and 3 are extracted from the right and left sides of the resin packaging material 4, and then are bent like crab legs along the side face and bottom face of the resin packaging material 4. Side plates 3a and 3a of the lead terminals 3 and 3 disposed along the side face of the resin packaging material 4 are formed with solder non-attached surfaces 11 and 11 created by removing solder plating from parts of the lead terminals 3 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-type solid electrolytic capacitor, and more particularly, to a chip-type solid electrolytic capacitor in which a solder fillet is not generated when surface-mounted on a circuit board.

[0002]

2. Description of the Related Art Similarly to other chip components, various types of terminal shapes have been devised in consideration of the stability at the time of mounting, solderability, space saving, and the like, as with other chip components. As an example, FIG. 5 shows a cross-sectional view of a crab-foot-shaped chip-type solid electrolytic capacitor.

The chip type solid electrolytic capacitor 1 includes a capacitor element 2 formed by forming a cathode layer 2b on a sintered body of valve metal powder such as tantalum having an anode lead 2a implanted at one end.

In forming the capacitor element 2 into chips, lead terminals 3 and 3 are attached to an anode lead 2a and a cathode layer 2b, and then put into a molding die to surround the capacitor element 2 with heat-resistant synthetic resin. The resin exterior body 4 is formed. Then, the lead terminals 3, 3 protruding outward from the resin exterior body 4 are bent in a crab-foot shape along the side and bottom surfaces of the resin exterior body 4.

According to this, as shown in FIG. 6, the chip-type solid electrolytic capacitor 1 can be stably mounted on the solders 5, 5 applied to the circuit board PW, and is heated to a predetermined temperature. By melting the solders 5 and 5 in the heating chamber, the chip-type solid electrolytic capacitor 1 can be soldered to the circuit board PW.

[0006]

However, there is a problem that a solder fillet 5a is generated at the time of soldering. That is, since the solder plating S is applied to the lead terminals 3, the molten solder material crawls up to the side surfaces of the lead terminals 3, 3, and as a result, the flared spread as shown in FIG. The resulting solder fillet 5a is generated.

Since the solder fillet 5a is often larger than the mounting area of the chip-type solid electrolytic capacitor 1, it is necessary to increase the distance between adjacent components in anticipation of that. This has been an obstacle to achieving high-density mounting.

[0008]

According to the present invention, the generation of solder fillets can be effectively prevented. That is, the present invention provides a capacitor element having a cathode layer formed on a sintered body of valve action metal powder having an anode lead implanted on one end surface, and a pair of anode elements connected to each of the anode lead and the cathode layer. And a resin exterior body formed around the capacitor element such that the tip end side of each of the lead terminals is exposed, and the tip end side of each of the lead terminals is a side surface and a bottom surface of the resin exterior body. In the chip-type solid electrolytic capacitor bent in a crab-foot shape along, the side plate portion of the lead terminal arranged along the side surface of the resin outer package is formed by removing solder plating of the lead terminal. It is characterized in that a solder non-adhering surface is provided.

The solder non-adhering surface may not be provided on the entire surface of the side plate portion, but the solder plating of the lead terminal may be left on a portion below the side plate portion. For example, by leaving the solder plating of the lead terminal in the range of about 0.1 mm rising from the crab-foot-shaped bottom plate, when mounting on a circuit board, it is extremely small within a range that does not affect the mounting area. A fillet is made, so that the quality of the soldering can be visually checked. Also, the soldering strength is increased about 1.5 times.

[0010]

Next, an embodiment of the present invention will be described. FIG. 1 is a sectional view of a chip type solid electrolytic capacitor 10 according to this embodiment, and FIG. 2 is a perspective view thereof.

In this chip type solid electrolytic capacitor 10, as in the conventional example described with reference to FIG. 5, a cathode layer is formed by sintering a valve action metal powder such as tantalum having an anode lead 2a implanted at one end. 2b, and a resin package 4 made of a heat-resistant synthetic resin formed therearound.

A pair of lead terminals 3, 3 connected to the anode lead 2a and the cathode layer 2b are drawn out from both sides of the resin outer case 4, and are bent along the side and bottom surfaces of the resin outer case 4.

That is, each of the lead terminals 3 is bent in a crab-foot shape, and each of the terminals has a side plate portion 3a along the side surface of the resin outer case 4 and a bottom plate portion 3b along the bottom surface of the resin outer case 4. However, according to the present invention, the side plates 3a, 3a
Are formed with solder-free surfaces 11, 11 formed by removing the solder platings S, S of the lead terminals 3, 3.

The solder non-adhering surface 11 can be formed by applying a tape before plating and removing the tape after plating by a stripe plating method or a method of irradiating a laser to the plating surface to remove the plating. it can.

According to the actual production process, as shown in FIG. 3, the chip type solid electrolytic capacitor 10 has the capacitor element 2 mounted between the lead terminals 3 and 3 of the lead frame 30, and A resin outer package 4 is formed around each capacitor element 2 in a molding die (not shown).
Before the lead terminals 3 are separated from the lead frame 30, the side plate portions 3 of the lead terminals 3, 3 are formed.
It is preferable in terms of productivity to form the solder non-adhesion surfaces 11 by irradiating a portion corresponding to a and 3a with, for example, a laser.

Normally, the lead frame 30 is made of stainless steel, and the ground is exposed on the non-soldering surfaces 11, 11, so that the solder does not adhere to the non-soldering surfaces 11, 11.

According to this configuration, as shown in FIG. 4, in this chip-type solid electrolytic capacitor 10, when the circuit board PW is soldered by the reflow soldering method, the solders 5, 5 are connected to the side plates. Crawling does not occur on the portions 3a, 3a, and no solder fillet is generated. Therefore, the distance between adjacent components can be shortened accordingly, and high-density mounting can be achieved.

As another example, the entire surfaces of the side plates 3a, 3a are not solder-adhered surfaces 11, 11, but solder plating of the lead terminals 3, 3 is provided on a portion below the side plates 3a, 3a. May be left.

For example, by leaving the solder plating of the lead terminal in a range of about 0.1 mm rising from the crab-shaped bottom plates 3b, 3b, the soldering strength is increased about 1.5 times and the fillet is removed. By making on purpose, the quality of the soldering can also be visually checked.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Actually, A4 size (length 32 mm × width 1.6)
mm × 1.6 mm) lead terminals are bent in a crab-foot shape to prepare 10 chip-type solid electrolytic capacitors.
For five of them, a solder non-adhering surface was formed on the side plate of the lead terminal as an embodiment of the present invention. The remaining five were used as they were as comparative examples.

In both the examples and the comparative examples, they are placed on a cream solder applied on a circuit board and soldered by a reflow soldering method, and as shown in FIGS. Was measured.

As a result, for the five embodiments of the present invention, the spread width W of the solder was 3.36 mm and 3.35 m.
m, 3.40 mm, 3.38 mm and 3.39 mm
The average value was 3.38 mm.

On the other hand, the spread width W of the five solders of the comparative example was 10.08 mm, 10.10 mm, 10.0
They were 9 mm, 10.10 mm and 10.07 mm, and the average value was 10.09 mm. As described above, according to the present invention, it was verified that the area required for mounting can be reduced by about ３ compared with the comparative example (conventional example).

[0024]

As described above, according to the present invention,
A resin sheath is formed around a capacitor element made of a sintered body of a valve metal powder, a pair of lead terminals is drawn out from both left and right sides thereof, and bent into a crab-foot shape along the side and bottom surfaces of the resin sheath. The chip-type solid electrolytic capacitor has a solder-free surface formed by removing the solder plating of the lead terminal on the side plate portion arranged along the side surface of the resin outer package of the lead terminal, so that the lead terminal melts. It is possible to effectively prevent the generation of the solder fillet due to the solder material crawling up. Also, the amount of halogen and lead used is reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a chip-type solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a perspective view of the chip-type solid electrolytic capacitor according to the embodiment.

FIG. 3 is a schematic diagram for explaining a preferred production mode of the chip-type solid electrolytic capacitor according to the embodiment.

FIG. 4 is a schematic view showing a mounted state of the chip-type solid electrolytic capacitor according to the embodiment on a circuit board.

FIG. 5 is a sectional view showing a conventional example.

FIG. 6 is a schematic diagram showing a state of mounting on the circuit board of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Chip type solid electrolytic capacitor 11 Solder non-adhering surface 2 Capacitor element 2a Anode lead 2b Cathode layer 3 Lead terminal 3a Side plate 3b Bottom plate 4 Resin exterior body 5 Solder 5a Solder fillet S Solder plating PW circuit board

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenichi Ichisugi 145 Ichikawa-cho, Ishikawa-cho, Ishikawa-gun, Fukushima Elner Fukushima Co., Ltd. 145 Elner Fukushima Co., Ltd.Ishikawa Factory (72) Inventor Noriaki Suzuki 145 Ishikawa-cho, Ishikawa-cho, Ishikawa-gun, Fukushima Prefecture Elner Fukushima Corporation Ishikawa Factory

Claims (2)

[Claims] 1. A capacitor element having a cathode layer formed on a sintered body of valve action metal powder having an anode lead implanted on one end face, and a pair of cathode elements connected to the anode lead and the cathode layer, respectively. A lead terminal, including a resin exterior body formed around the capacitor element such that a tip end side of each of the lead terminals goes outside, and a tip end side of each lead terminal is on a side surface and a bottom surface of the resin exterior body. In a chip-type solid electrolytic capacitor which is bent along a crab-foot shape, a side plate portion of the lead terminal arranged along a side surface of the resin exterior body has a solder formed by removing solder plating of the lead terminal. A chip-type solid electrolytic capacitor having a non-adhesive surface. 2. The solid electrolytic capacitor according to claim 1, wherein solder plating of said lead terminals is left in a part below said side plate portion.