JPH02244607A - Manufacture of electronic part - Google Patents

Abstract

PURPOSE:To prevent the danger causing a fire and to obtain an electronic part having high degree of safety by a method wherein a fused material covering a fuse metal is diffused, and an empty space is formed. CONSTITUTION:The main box 26 of a ceramic capacitor is obtained by alternately laminating a ceramic layer 21, on which no electrode is formed, a layer 22 having an inner electrode 24, and a layer 23 having an inner electrode 25. A before-sheathing electronic part 34, having a fuse metal 30 which is electrically series-connected to the outer electrode 28 of the main body 26, is prepared, a fusable material is coated on a metal 30 by heating, and a coated part 35 is formed. Then, after porous insulative region has been sheathed on the outer surface of the main body 26, an insulative resin layer 36 is formed by heating and sintering. At this time, the coated part 34 formed by the foreprocessing is fused simultaneously, it is absorbed by diffusion into the layer 36 and escaping to outside from an insulative resin layer 11, the coated layer 35 is vanished, and an empty space 37 formed on the circumference of the metal 30. Then, after the main body 26 has been preheated, a sheathing resin layer 38 is formed by coating thermosetting resin on the layer 36, and an electronic part 39 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of manufacturing an electronic component including a fuse metal on the outer surface of a main body portion.

(Prior Art) Conventionally, as an electronic component including a fuse metal on the outer surface of a main body portion, there is an electronic component 1 shown in FIG. 6 in which a fuse metal is electrically connected in series to a multilayer ceramic capacitor.

Such an electronic component 1 has internal electrodes 2 and 8 and conductive wires at both ends of a main body portion 5, which is buried so that internal electrodes 2.3 are alternately drawn out to opposite ends through a ceramic layer 4. A pole 6 and a second external N pole 7 are formed with the first external electrode 1 connected to the main body part 5, and the internal electrodes 2 and 3 are connected between the first external electrode 6 and the second external electrode 7 on the side of the main body part 5. A third external electrode 8 is formed which is not conductively connected to the second external electrode 8.
A first external lead member 9 is attached to the external electrode 7. The second external lead members 10 are soldered to the third external electrodes 8, and the first external electrodes 6. A linear fuse metal 11 is connected between the eighth external electrodes 8, and the entire surface of the main body portion 5 is covered with an exterior resin material 12.

However, in such electronic components, the fuse metal is pressed against the outer surface of the main body by the exterior resin material, so the main body, which is a multilayer ceramic capacitor, may go into short mode for some reason and the fuse metal may Even if an attempt was made to melt the fuse and cut the circuit, there was no place for the molten fuse metal to escape, so the current would continue to flow in the molten state, creating a risk of causing a fire in the exterior resin material due to heat generation.

In order to solve these problems,
An electronic component described in Japanese Patent No. -85133 has been proposed.

The feature of the electronic component described in this Japanese Utility Model Publication No. 61-85133 is that, as shown in FIG. 7, a space 13 is provided around the fuse metal 11 of the electronic component 1 shown in FIG. It is in. In other words, the space 13 is provided around the fuse metal 11 so that the fuse metal 11 melted by excessive current can escape, thereby improving the fusing performance against excessive current. In addition, as shown in FIG. 8, the method for manufacturing an electronic component having this space 13 is such that, before the entire surface of the main body portion 5 is coated with the exterior resin material 12, most of the fuse metal pAll is coated with polyurethane. A heat-shrinkable resin 14 such as
is thermally shrunk during curing after being coated with the exterior resin material 9.

(Problems with the prior art) However, although the electronic component manufacturing method described above can form a space where the fuse metal can escape, the heat-shrinkable resin may remain attached to the fuse metal. In this case, there was a risk that the remaining heat-shrinkable resin would burn due to the heat from the fuse metal, causing a fire.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems, and aims to provide a highly safe method of manufacturing electronic components.

(Means for Solving the Problems) The present invention is a process of preparing an electronic component in which a fuse metal is electrically connected in series to any of external electrodes formed on the outer surface of a main body portion for extracting electrical characteristics. A step of coating at least the fuse metal with a material that is solid or semi-solid at room temperature and melts when heated to form a covering portion; A step of applying a porous insulating resin on at least the covering portion and melting it by heating. forming an insulating resin layer by baking, and forming a space by melting the covering portion and absorbing it into the insulating resin layer; and applying an exterior resin layer made of thermosetting resin to at least the outside of the external electrode and a step of forming the electronic component on the outer surface of the electronic component so as not to prevent the electronic component from being pulled out.

(Function) In the present invention, a material that is solid or semi-solid at room temperature and melts when heated is coated in advance to cover the fuse metal to form a covering portion, and then a porous insulating resin is applied onto the covering portion. By heating and baking, an insulating resin layer is formed, and the coating is melted and absorbed into the insulating resin layer to form a space, so that materials that can cause combustion due to the heat of the fuse metal adhere to the fuse metal. This will eliminate the possibility of remaining unused.

(Effects of the Invention) According to the present invention, the material that is solid or semi-solid at room temperature and melts when heated in the covering part that covers the fuse metal diffuses into the insulating resin layer formed on the covering part. This prevents materials that could cause combustion due to the heat of the fuse metal from remaining on the fuse metal, reducing the risk of fire. can be avoided.

(Example) Hereinafter, an example of the method for manufacturing an electronic component of the present invention will be described in detail with reference to the drawings.

First, as shown in FIGS. 1 and 2, a ceramic layer 22 is formed, with a ceramic layer 21 on which no internal electrodes are formed as the top layer, and an internal electrode 24 drawn out at one end formed on the main surface; A main body part 26 of a multilayer ceramic capacitor is obtained in which internal electrodes 25 drawn out to one side are alternately laminated with ceramic layers 23 formed on the main surface, and an internal 1i pole 24 is attached to one end of the main body part 26. The first external electrode 274 is electrically conductively connected to the internal electrode 25 on the side of the main body portion 26 .
8, and a third external electrode 29 which is not electrically conductively connected to the internal electrodes 24, 25 is formed at the other end of the main body portion 26. And the second external electrode 28
．． A thick film of fuse metal 30 is bridge-formed on the outer surface of the main body portion 26 between the third external electrodes 29, and solder 31 is applied to each of the first external electrode 27 and the third external electrode 29.
The first external lead member 32 and the second external lead member 33 were connected, and the fuse metal 80 was electrically connected in series to the second external electrode 28 formed on the outer surface of the main body portion 26 for taking out electrical characteristics. Electronic parts 34 before exterior packaging
prepared. Although the fuse metal 30 in the form of a thick film is shown as being formed on the outer surface of the electronic component 84, the fuse metal 30 is not limited to a thick film, and may be formed of a metal wire or the like.

Next, as shown in FIG. 3, a material that is solid or semi-solid at room temperature and melts when heated, such as wax, is applied to cover the fuse gold/X30 provided on the outer surface of the main body portion 26, and the covering portion 35 is form. In this step, wax was used as a material that is solid or semi-solid at room temperature and melts when heated, but any other material such as paraffin may be used.

Next, the entire outer surface of the main body portion 26 is coated with a porous insulating resin, such as a phenol resin, at room temperature using a method such as a dipping method, and then the phenol resin is coated at a temperature of 150 to
By heating and baking at a temperature of ao.degree. C., an insulating resin layer 86 as shown in FIG. 4 is formed. At this time, the covering portion 34 formed in the previous step melts at the same time and diffuses into the insulating resin layer 36 or escapes from the insulating resin layer 11 to the outside and is absorbed. The layer 35 disappears and a space 37 is formed around the fuse metal 30.

This space 37 functions as an escape area when the electronic component goes into short mode and the fuse metal 30 melts. Although phenol resin was used as the porous insulating resin in this step, it is not limited to this.

Next, after preheating the main body portion 26 on which the insulating resin layer 36 is formed, a thermosetting resin, such as a powdered epoxy resin, is applied onto the insulating resin layer 36 to melt and harden it.
Furthermore, an exterior resin layer 38 was formed to obtain an electronic component 39 as shown in FIG. The reason why the exterior resin layer 38 was further formed on the insulating resin layer 361- in this step is because the mechanical strength and humidity of the electronic component would deteriorate if only the porous insulating resin layer 36 was used. Further, although powder epoxy was used as the thermosetting resin in this step, the present invention is not limited to this.

Note that among the above-mentioned steps, if the preheating step of the step of forming the outer resin layer is also used as the step of forming the insulating resin layer, energy efficiency can be improved and costs can be reduced.

Further, in the above-mentioned embodiment, the insulating resin layer and the exterior resin layer are formed on the entire outer surface of the main body portion, but the present invention is not limited to this, and the insulating resin layer and the exterior resin layer are formed on the entire outer surface of the main body portion. The insulating resin layer and the exterior resin layer may be formed leaving only the external electrodes. In this case, it can be treated as a chip-type electronic component without attached lead wires, and can be surface-mounted on a circuit board.

Further, in the above-mentioned embodiments, a laminated ceramic capacitor with a fuse metal on the outer surface is shown, but the present invention is not limited to this, and electronic components other than the laminated ceramic capacitor with a fuse metal on the outer surface are shown. Needless to say, it can be adapted to

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view for explaining the method for manufacturing the main body portion of the electronic component of the present invention, and FIGS. 2 to 5 are for explaining the manufacturing method of the electronic component of the present invention. 6 and 7 are partial side sectional views showing a conventional electronic component, and FIG. 8 is a partial side sectional view for explaining a conventional method of manufacturing an electronic component. 21.22, 23...Ceramic layer 24.25...Internal electrode 26...Body portion 27...First external electrode 28...Second external electrode 29...Third external electrode 30. ...Fuse metal 31...Solder 32...First external lead member 83...Second external lead member 84...Electronic component 35 before exterior packaging...Coating portion 36...Insulating resin layer 37...Space 38...Exterior resin layer 39...Electronic component. Diagram drawing diagram Mazu drawing 1

Claims (1)

[Claims] A step of preparing an electronic component before packaging, in which a fuse metal is electrically connected in series to one of the external electrodes formed on the outer surface of the main body portion for extracting electrical characteristics, and the electronic component is solid at room temperature. Alternatively, a step of coating at least the fuse metal with a semi-solid material that melts when heated to form a covering part, and applying a porous insulating resin on at least the covering part and baking it by heating. forming an insulating resin layer and melting the covering portion and absorbing it into the insulating resin layer to form a space; and drawing an exterior resin layer made of a thermosetting resin to the outside of at least the external electrode. forming the electronic component on the outer surface of the electronic component so as not to interfere with the process.