JPH02106031A - Manufacture of molded chip tantalum solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve heat efficiency without deteriorating characteristics of a capacitor element by fixing a cathode terminal to the capacitor element by means of an adhesive before finally curing a conductive bonding material. CONSTITUTION:A cathode terminal 7 is fixed to a capacitor element 1 by means of an adhesive 13 to 15 before a conductive bonding material 4, 6 is cured finally. Since the adhesive 13 to 15 is cured in a shorter period of time than the conductive bonding material 4, 6, the capacitor element 1 is not subjected to so strong stress as to deteriorate characteristics of the capacitor element 1 while the adhesive 13 to 15 is cured. When the conductive bonding material 4, 6 is cured finally, the total heat capacity is not increased since the conductive bonding material 4, 6 has been bonded sufficiently to a cathode connecting part 5b of the capacitor element 1 by the effect of the adhesive 13 to 15. In this manner, heat can be transferred to the conductive bonding material efficiently and the required quantity of heat can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a molded chip tankle solid electrolytic capacitor used, for example, in a high-print IC circuit.

[Conventional technology]

Conventionally, tantalum solid electrolytic capacitors have been used in which tantalum metal is used as an anode body, an oxide film is formed on the surface of the anode body by positive oxidation to form a dielectric material, and a solid electrolyte is brought into close contact with this oxide film to form a negative oxide film. ing. Such a tantalum solid electrolytic capacitor may be coated with a molded resin, have a terminal structure suitable for face bonding, and be configured as a chip capacitor to be incorporated into a hybrid IC circuit.

In such molded chip tantalum solid electrolytic capacitors, the capacitor element and the cathode terminal led out to the outside are connected via a fuse, so that the surrounding circuitry can be protected in the event of a short circuit caused by reverse insertion into the set or overvoltage. Products have been proposed that improve safety by preventing burns and the like. The inventor of the present invention has made several proposals regarding such molded chip Kuntal solid electrolytic capacitors.

FIG. 3 shows the basic configuration of a molded chip tantalum solid electrolytic capacitor (hereinafter referred to as "chip capacitor") that was previously proposed by the inventor of the present invention.

This chip capacitor includes a capacitor element 1, an anode lead wire 2 led out from the capacitor element 1, an anode terminal 3 connected to the anode lead fI2, and a conductive bonding material 4 on the surface of the cathode layer of the capacitor element 1. The connected fuse 5 and the cathode terminal 7 connected to the fuse 5 by a conductive bonding material 6 similar to the conductive bonding material 4 are molded and packaged so that the anode terminal 3 and the cathode terminal 7 are led out to the outside. is applied and housed in a molded resin (not shown). Anode lead wire 2 of capacitor element 1
An insulating plate 9 made of Teflon or the like is provided near the lead-out portion.

Capacitor element l is made by molding tantalum powder and firing it in a vacuum, forming an oxide film thereon as a dielectric, forming an electrolyte such as manganese dioxide on the surface of this oxide film, and then forming a carbon layer and a cathode layer. The anode lead wire 2 led out from the capacitor element 1 is made of tantalum metal. The anode terminal 3 is made of nickel nickel silver, 4270I, or stainless steel plated with solder on steel. Further, the fuse 5 is made of a plate-shaped or linear low-melting point alloy material, and the molding resin used is epoxy resin, silicone resin, or the like. Furthermore, the conductive bonding material 4.6 is, for example,
These include conductive adhesives and solder (including cream solder).

An insulating coating layer 10 is formed on the cathode layer on the surface of the capacitor element 1 by dipping, coating, sheet pasting, etc., except for some of the three anode terminals. The above-mentioned fuse 5 has one end 5a that is connected to the insulating coating layer 1.
It is connected to the surface of the capacitor element 1 on which 0 is not formed.

The fuse 5 is arranged so as to be wrapped around the capacitor element 1 along the insulating coating R10R surface, and the other end 5b is on the opposite side of the capacitor element 1 from the one end 5a. , are connected to the cathode terminal 7.

For example, when this chip capacitor breaks down due to a short circuit occurring in the capacitor element 1, the fuse 5
A large current flows through the fuse 5, and the fuse 5 is blown. This prevents other circuit components from being damaged in the event of a short circuit in the capacitor element 1, thereby improving safety when using the chintube capacitor.

The aforementioned insulating coating N10 covers the one end 5 of the fuse 5.
Insulating between parts other than a and the surface of the capacitor element 1,
This is provided for the purpose of ensuring the length necessary to obtain the desired fusing characteristics of the fuse 5. That is, when the fuse 5 comes into contact with the surface of the capacitor element 1, a current flows through this contact portion, causing changes in the characteristics of the chip capacitor such as changes in capacitance and the fusing characteristics of the fuse 5.

Therefore, when the insulating coating layer 10 is not provided, the characteristics of the chip capacitor and the blowing characteristics of the fuse 5 become unstable.

[Problems to be Solved by the Invention] In the chip capacitor as described above, when connecting the fuse 5 and the cathode terminal 7, as shown in FIG.
and the cathode terminal 7 are pressed together, and in this state, the conductive bonding material 6 is heated, and the conductive bonding material 6 is fully cured. For example, when an epoxy resin-based conductive adhesive is used as the conductive bonding material 6, the fuse 5 and the cathode terminal 7 are pressed together by the pair of elastic bodies 1112, and the temperature is increased to 150°C for 30 to 90 minutes. 18
A temperature of 0°C is maintained. However, at this time, stress is applied to the capacitor element 1 from the pair of elastic bodies 1112 over a long period of time, resulting in deterioration of characteristics such as leakage current in the chip capacitor. Furthermore, since a pair of elastic bodies +1゜]2 are brought into contact with the capacitor element 1 and the cathode terminal 7, the overall heat capacity becomes large, leading to deterioration of thermal efficiency and requiring a relatively long time to raise the temperature. was.

An object of the present invention is to provide a method for manufacturing a molded chip tantalum solid electrolytic capacitor that can contribute to improving thermal efficiency without causing deterioration in the characteristics of a capacitor element.

[Means to solve the problem]

The method for manufacturing a molded buttantal solid electrolytic capacitor of the present invention involves interposing a conductive bonding material between the cathode connection portion and the cathode terminal when connecting the cathode connection portion of the capacitor element and the cathode terminal. The cathode terminal is fixed to the capacitor element using an adhesive that can be cured in a shorter time than the conductive bonding material, and then the conductive bonding material is fully cured to connect the cathode terminal to the cathode connection portion. Features.

[Effect]

According to the configuration of the present invention, the cathode terminal is fixed to the capacitor element with an adhesive before the conductive bonding material is fully cured. At this time, a conductive bonding material is interposed between the cathode terminal and the cathode connection portion of the capacitor element. Since the adhesive can be cured in a shorter time than the conductive bonding material, when the adhesive is cured, stress that would deteriorate the characteristics of the capacitor element is not applied to the capacitor element. After the adhesive is cured and the cathode terminal is fixed to the capacitor element, main curing of the conductive bonding material is performed. At this time, the conductive bonding material and the cathode connection part of the capacitor element are sufficiently bonded together by the adhesive, so there is no need for a pair of elastic bodies used in the past, and the overall heat capacity is reduced. It never gets bigger. This reduces the amount of heat required when the conductive bonding material must be maintained at a low heating temperature during main curing.

〔Example〕

FIG. 1 shows a molded chip tantalum solid electrolytic capacitor (hereinafter referred to as a "chip capacitor") according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view thereof. In FIGS. 1 and 2, the same parts as those shown in FIG. 3 described above are given the same reference numerals. A plate-shaped fuse 5 is wound around the capacitor element 1 having an insulating coating layer 10 formed on its surface along the surface of the insulating coating layer 10.
One end 5a thereof is connected to the surface of the cathode layer of the capacitor element 1 which is not covered with the insulating coating layer 10. The other end 5b of the fuse 5 is surface-connected to the cathode terminal 7 as a cathode connection portion of the capacitor element l.

For this surface connection, first, a conductive bonding material 6 such as an epoxy resin conductive adhesive is applied to the connection surface 7a of the cathode terminal 7. Next, the capacitor element 1 to which the fuse 5 is connected is placed against the cathode terminal 7, with the other end 5b of the fuse 5 coming into contact with the conductive bonding material 6 applied to the connection surface 7a of the cathode terminal 7. Place it like this. In this state, the cathode terminal 7 and the capacitor element 1 are fixed with an adhesive 13, 14, 15, such as an ultraviolet curable resin, which can be cured in a relatively short time. The adhesives 13, 14, and 15 are cured in a sufficiently short time.
Therefore, during this curing, capacitor element 1 and cathode terminal 7
Even in the case where the other end 5b of the fuse 5 is crimped to the conductive bonding material 6 by applying a force acting in a direction in which they approach each other, an undesirable degree of stress will not be applied to the capacitor element l. do not have.

After curing the adhesive 13.14.degree. 15, main curing of the conductive bonding material 6 is performed. When the conductive bonding material 6 is an epoxy resin-based conductive adhesive, the main curing is performed by heating the conductive bonding material 6 for 90 minutes in a curing furnace at a temperature of 175'C. It will be done. In this way, the cathode terminal 7 is connected to the end 5b of the fuse 5, which is the cathode connection of the capacitor cord 1. Note that the adhesives 13, 14, and 15 mentioned above are selected from a type that has sufficient adhesive strength in an environment at a temperature of about 180°C.

The above-mentioned connection between the cathode terminal 7 and the capacitor element l,
After the anode lead wire 2 is connected to the anode terminal 3, a mold exterior is applied so that the anode terminal 3 and the cathode terminal 7 are led out to the outside.

In this way, in this embodiment, when the conductive bonding material 6 connecting the cathode terminal 7 and the fuse 5 is fully cured, the cathode terminal 7 is
In order to press the connecting surface 7a of the fuse 5 to the other end 5b of the fuse 5, there is no need to use an elastic body or the like as in the conventional case. Therefore, no stress is applied to the capacitor element l for a long time (this capacitor element l
There is no deterioration in characteristics such as leakage of 12A.

Furthermore, since the elastic body does not come into contact with the capacitor element l, the cathode terminal 7, etc., the overall heat capacity does not increase unnecessarily, and the amount of heat is efficiently transferred to the conductive bonding material 6.
Therefore, the amount of heat required for heating during main curing of the conductive bonding material 6 is relatively small.

Furthermore, since the elastic body and the like are not required, the structure for performing the main curing can be simplified and downsized. Therefore, during the main curing, a large number of chip capacitors can be processed at once in the curing furnace, improving productivity.

In the above embodiment, a chip capacitor in which the cathode terminal 7 and the cathode layer of the capacitor element 1 are connected via the fuse 5 was explained as an example, but the present invention can also be applied to a chip capacitor without the fuse 5. It can be suitably implemented. That is, an insulating coating layer 1 is formed on the surface of the capacitor element 1.
0, and when the surface of the capacitor element 1 is used as a cathode connection part and the connection surface 7a of the cathode terminal 7 is directly connected to this cathode connection part, a conductive bonding material 6 is applied to this connection surface 7a.
is applied, and the conductive bonding material 6 is brought into close contact with the surface of the capacitor element 1, and the cathode terminal 7 and the capacitor element 1 are fixed with adhesive 1314.15. After this, the conductive bonding material 6 is fully cured. Just do it like this.

[Effects of the Invention] According to the method for manufacturing a molded chip tantalum solid electrolytic capacitor of the present invention, before main curing of the conductive bonding material,
The cathode terminal is fixed to the capacitor element by adhesive. Since the adhesive can be cured in a shorter time than the conductive bonding material, when the adhesive is cured, stress that would deteriorate the characteristics of the capacitor element is not applied to the capacitor element. When the conductive bonding material is fully cured, the conductive bonding material and the cathode connection portion of the capacitor element are sufficiently adhered to each other by the action of the adhesive, so that the pair of elastic bodies used in the past is not required. Therefore, the overall heat capacity does not increase. As a result, in the case where the heating temperature must be maintained during the main curing of the conductive bonding material, the applied amount of heat is efficiently transmitted to the conductive bonding material, thereby reducing the required amount of heat.

Furthermore, as a result of not requiring the aforementioned elastic body,
It becomes possible to simplify and downsize the configuration for performing the main curing.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the basic structure of a molded chip tantalum solid electrolytic capacitor according to an embodiment of the present invention;
FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a sectional view showing the basic structure of a molded buttantal solid electrolytic capacitor previously proposed by the inventor of the present invention. 1... Capacitor element, 4.6... Conductive bonding material, 5
... Fuse, 5b... End (cathode connection part), 7.
... Cathode terminal, 7a... Connection surface, 13, 14.15.
・・Adhesive LP・）Scientist 1

Claims (1)

[Claims] When connecting the cathode connection portion and the cathode terminal of the capacitor element, a conductive bonding material is interposed between the cathode connection portion and the cathode terminal, and cures in a shorter time than the conductive bonding material. A molded chip tantalum solid electrolytic capacitor, characterized in that a cathode terminal is fixed to a capacitor element with an adhesive that can be bonded, and then the conductive bonding material is fully cured to connect the cathode terminal to the cathode connection portion. manufacturing method.