JP3413591B2 - Molded exterior resin chip type solid electrolytic capacitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin resin chip type solid electrolytic capacitor having a molded outer package.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional mold-clad resin chip type solid electrolytic capacitor has an anode electrode 2 and a cathode electrode 3 paired with a tantalum element 1 electrically connected to each other, and the outer periphery thereof is molded resin. 4 is used to hermetically seal.

Further, the anode electrode 2 and the cathode electrode 3 exposed from the mold resin 4 are bent along the shape of the lower surface of the mold resin 4 to form a surface mount type. S is a conductive adhesive.

[0004]

By the way, in the above-mentioned molded package resin chip type solid electrolytic capacitor, moisture and the like inside may be gasified (water vapor etc.) due to heating during soldering and reflow mounting.

This type of chip type solid electrolytic capacitor is
Although the structure is hermetically sealed, the tantalum element 1 and the electrodes 2,
Due to the adhesiveness between the mold 3 and the mold resin 4, a tombstone phenomenon occurs in which moisture inside is gasified (water vapor etc.) due to heating during soldering and reflow mounting, and is injected to the outside, or outside the mold resin. Parts may be blown off, which may cause a phenomenon.

FIG. 3 shows the gas flow in the conventional example. The gas flow in the conventional example is determined by the strength of adhesion between the tantalum element 1 and the electrodes 2, 3 and the molding resin 4.

When the adhesion is weak, as shown in FIG. 3 (a), the adhesive is discharged from the interface between the tantalum element 1 and the electrodes 2 and 3 and the molding resin 4, and the parts in the vicinity thereof are blown off. 3B, a tombstone phenomenon occurs in which a crack 5 is generated in the thin portion of the mold resin 4 and ejected, as shown in FIG. 3B.

Japanese Patent Laid-Open Nos. 55-77160 and 6
No. 3-12175, Japanese Patent Application Laid-Open No. 9-172103, Japanese Patent Publication No. 2-39865, and Japanese Utility Model Laid-Open No. 53-661.
No. 71, No. 4-256346, No. 4
-256347, Japanese Patent Laid-Open No. 7-297079, etc. disclose various techniques for forming holes in a mold resin.

However, JP-A-55-77160, JP-A-63-12175, and JP-A-9-17.
The techniques disclosed in Japanese Patent No. 2103, Japanese Patent Publication No. 2-39865, and Japanese Utility Model Laid-Open No. 53-66171 are semiconductor I
Holes are provided in a part of the exterior resin for the purpose of preventing cracks in the exterior resin of C and internal elements (thin layers, etc.). However, a chipping defect may occur during molding of the exterior resin. Since there is a hole in contact with the element, it may damage the element. Furthermore, no measures have been taken to inject gas into the electrode part, and it is impossible to completely prevent the tombstone phenomenon. .

The techniques disclosed in Japanese Patent Application Laid-Open Nos. 4-256346 and 4-256347 are LSIs.
Although a hole is provided in a part of the exterior resin for the purpose of letting out the gas generated at the time of cooling, it is impossible to completely prevent the tombstone phenomenon.

Further, the technique disclosed in Japanese Patent Laid-Open No. 7-297079 discloses a surface mount type electronic component and a mounting structure of the surface mount type electronic component, in which an electrode is provided with a hole penetrating from a mounting face to a non-mounting face, The purpose is to prevent the tombstone phenomenon and to improve the soldering strength by sucking up the solder paste due to the cream solder gas and the capillary phenomenon. It is the purpose, and it is impossible to surely prevent the tombstone phenomenon.

An object of the present invention is to provide a molded package resin chip type solid electrolytic capacitor which surely prevents the tombstone phenomenon or the phenomenon of blowing a component outside the molding resin.

[0013]

In order to achieve the above object, a molded package resin chip type solid electrolytic capacitor according to the present invention is provided with an external lead terminal lead-out portion of an anode electrode and a cathode electrode sealed in a mold resin. The mold resin has minute holes for venting gas from the vicinity to the non-mounting surface of the mold resin.

The gas vent hole has a diameter of 0.2 mm.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 (a) is a cross-sectional view showing a molded package resin chip type solid electrolytic capacitor according to an embodiment of the present invention, (b) is a cross-sectional view for explaining the operation, and (c) is the present invention. FIG. 6 is a cross-sectional view showing a method for manufacturing a resin packaged solid electrolytic capacitor with mold exterior according to one embodiment.

In FIG. 1 (a), a molded package resin chip type solid electrolytic capacitor according to an embodiment of the present invention is
The anode electrode 2 and the cathode electrode 3 forming a pair are electrically joined to the tantalum element 1, and the outer periphery thereof is hermetically sealed with a mold resin 4. S is a conductive adhesive.

Further, the anode electrode 2 and the cathode electrode 3 exposed from the mold resin 4 are bent along the shape of the lower surface side of the mold resin 4 to form a surface mount type. The structure is not limited to the surface mount type structure.

Further, in one embodiment of the present invention, the anode electrode 2 and the cathode electrode 3 of the chip type solid electrolytic capacitor are
Two holes 6 for venting internal gas are formed from the vicinity of the external lead terminal lead-out portions 2a and 3a toward the non-mounting surface (the upper surface in FIG. 1) 4a of the mold resin 4.

The gas vent hole 6 is formed as shown in FIG.
One of the molds 7 for molding the molding resin 4 has a diameter of 0.2.
mm pins 8 are provided, and the pins 8 are used to form the mold resin 4.

The reason why the hole 6 is formed from the vicinity of the external lead terminal lead-out portions 2a, 3a of the anode electrode 2 and the cathode electrode 3 toward the non-mounting surface 4a of the mold resin 4 is the mold used for mold exterior. 7 and 9 are separated into an upper mold and a lower mold with the external lead terminal lead-out portions 2a and 3a of the anode electrode 2 and the cathode electrode 3 as boundaries, and move vertically and clamp the lead terminal between them. Therefore, since the following problems can be prevented, the upper die 7 is provided with a pin 8 having a diameter of 0.2 mm.
By providing the individual pieces, the gas vent holes 6 can be easily formed in the mold resin 4 by using the pins 8.

The above-mentioned problems include (1) mold 7,
9 is separated into an upper mold and a lower mold with the vicinity of the external lead terminal lead-out parts 2a and 3a of the anode electrode 2 and the cathode electrode 3 as a boundary, and it moves vertically, so that it is difficult to provide a lateral hole. . (2) When the hole 6 is provided on the internal element, the positional accuracy of the internal element becomes important, and the pin 8 provided on the die 7 may hit the internal element and be damaged (characteristic deterioration). (3) When the pin 8 is shortened so as not to hit the internal element, that portion is covered with the mold resin, so that the effect of the present invention may not be exhibited.

From the above, it is easy to form the hole 6 in the non-mounting surface 4a of the mold resin 4 from the vicinity of the external lead terminal lead-out portions 2a, 3a of the anode electrode 2 and the cathode electrode 3 (on the lead terminal). In addition, since the positional accuracy can be sufficiently ensured, the stable hole 6 can be formed.

In one embodiment of the present invention, in order to form the gas vent hole 6 in the mold resin 4, as shown in FIG. 1 (c), the lead frame 10 on which the tantalum element 1 is mounted.
(External lead terminal lead-out portion 2 of the anode electrode 2 and the cathode electrode 3
(a, 3a vicinity) as a boundary, the upper mold 7 and the lower mold 9 are clamped, and the pin 8 of the upper mold 7 is applied to the external lead terminal lead-out portions 2a, 3a of the anode electrode 2 and the cathode electrode 3. , Resin is injected into the cavity 10 between the upper mold 7 and the lower mold 9,
Mold resin 4 is molded.

After that, the upper mold 7 and the lower mold 9 are separated,
The pin 8 of the upper die 7 is pulled out from the molding resin 4, and the molding resin 4 is degassed from the vicinity of the external lead terminal lead-out portions 2a, 3a of the anode electrode 2 and the cathode electrode 3 to the non-mounting surface 4a of the molding resin 4. The hole 6 is formed.

In one embodiment of the present invention, when mounting the lead terminals 2a, 3a of the anode electrode 2 and the cathode electrode 3 of the resin-molded solid electrolytic capacitor with molded outer packaging on a substrate, by heating during soldering and reflow mounting. , Moisture inside is gasified (water vapor etc.).

In this case, in one embodiment of the present invention, as shown in FIG. 1 (c), the internal gas flows from the vicinity of the lead terminals 2 a and 3 a of the anode electrode 2 and the cathode electrode 3 to the non-mounting surface of the mold resin 4. Since it is discharged from the hole 6 having a diameter of 0.2 mm provided toward 4a, it is possible to prevent the tombstone phenomenon and blowout of surrounding parts.

Table 1 shows the results of comparing the tombstone fraction defectives of the chip type solid electrolytic capacitor according to one embodiment of the present invention and the chip type solid electrolytic capacitor produced by the conventional manufacturing method.

[0029]

[Table 1]

As shown in Table 1, the conventional product has a problem, but the present invention does not cause a defect and has an effect of preventing tombstone. The test was conducted under test conditions: humidification of the capacitor for 24 hours (85 ° C., 90 to 95% RH): reflow mounting of the humidified capacitor (keeping at 240 ° C., 10 seconds equivalent).

The reason why the diameter of the gas vent hole 6 is set to 0.2 mm (two) in one embodiment of the present invention will be described based on Table 2.

[0032]

[Table 2] As shown in Table 2, when the diameter is 0.1 mm or less, the effect of suppressing the tombstone is small, and when the diameter is 0.3 mm or more, the molding resin 4 is chipped.

The reason for reaching the above is that the diameter is 0.1 mm.
It is presumed that the internal gas does not escape sufficiently below, and when the diameter is 0.3 mm or more, the pins 8 provided on the mold 7 and the mold resin 4 bite when the mold resin is molded, and the mold releasability deteriorates.

Therefore, a hole having a diameter of 0.2 mm is most effective. Since the non-mounting surface 4a of the mold resin 4 is stamped (polarity, lot number, capacity, standard, etc.), it is preferable that the number of holes 6 is small in terms of appearance.

In one embodiment of the present invention, the mold 7 for molding resin is provided with the pins 8 to form the gas vent holes 6. However, after the molding of the molding resin 4 is completed, a drill or the like is used. The same effect can be obtained by forming the holes 6.

Further, when the hole 6 is formed by using a drill or the like, the effect obtained even if the hole 6 is obliquely provided from the vicinity of the external lead terminal lead-out portions 2a, 3a to the non-mounting surface 4a of the mold resin 4 is obtained. Are the same.

[0037]

As described above, according to the present invention, the internal gas is discharged from the vicinity of the external lead terminal lead portions of the anode electrode and the cathode electrode toward the non-mounting surface of the mold resin. Therefore, it is possible to prevent the tombstone phenomenon and blowout of surrounding parts.

It is effective to set the diameter of the gas inside the outer electrode lead terminals of the anode electrode and the cathode electrode toward the non-mounting surface of the molding resin to 0.2 mm so that the gas is efficiently released. It can be carried out.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view showing a molded package resin chip type solid electrolytic capacitor according to an embodiment of the present invention,
(B) is sectional drawing explaining operation | movement, (c) is sectional drawing which shows the manufacturing method of the mold exterior resin chip type solid electrolytic capacitor which concerns on one Embodiment of this invention.

FIG. 2 is a cross-sectional view showing a molded package resin chip type solid electrolytic capacitor according to a conventional example.

FIG. 3 is a cross-sectional view illustrating a problem in a mold-clad resin chip type solid electrolytic capacitor according to a conventional example.

[Explanation of symbols]

1 tantalum element 2 Anode electrode 3 cathode electrode 4 Mold resin 6 Gas vent holes

Claims (2)

(57) [Claims] 1. A fine hole for degassing is formed in the mold resin from the vicinity of the external lead terminal lead-out portions of the anode electrode and the cathode electrode sealed in the mold resin to the non-mounting surface of the mold resin. Characteristic Molded exterior resin chip type solid electrolytic capacitor. 2. The mold-clad resin chip type solid electrolytic capacitor according to claim 1, wherein the gas vent hole has a diameter of 0.2 mm.