JPS6038858B2 - How to manufacture ceramic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a cylindrical ceramic capacitor with a metal cap.

Automatic mounting of ceramic capacitors onto printed circuit boards, etc. is being carried out.

FIG. 1 shows an example of a conventional cylindrical porcelain capacitor with a metal cap formed to enable automatic mounting. An inner electrode 3 is formed on the inner peripheral surface 2 of a cylindrical ceramic body 1 made of titanium oxide or the like, and an outer electrode 5 is formed on the outer peripheral surface 4 of the cylindrical ceramic body 1.
A metal cap 6 is placed over the lead-out portion 3a of the inner electrode 3 to the outer circumferential surface, and a similar metal cap 6 is placed over the outer electrode 5, and the metal cap 6 and the electrode 3 are bonded together by a soldering method.
, 5 are connected with solder 7. Reference numeral 8 denotes a protective film made of epoxy resin or phenol-modified epoxy resin for moisture proofing, electrical insulation, etc., and is provided on the entire outer peripheral surface except for the lead wire 9.

By the way, the following problem arises by providing the solder 7 for electrical connection and airtightness of the metal cap 6 as described above.

Due to heat treatment during solder bonding, cracks occur in the element body 1 of some ceramic capacitors, resulting in deterioration of insulation properties.

{Raw Solder 7, flux, or both may adhere to unnecessary parts and cause characteristic deterioration.

However, in some cases, air-tight solder bonding may become impossible due to the expansion of the air inside the element, and in such cases, when the resin for forming the protective film 8 is thermally cured, the air inside A pinhole is formed in the protective film 8 due to the outflow.

〇 When soldering a completed ceramic capacitor to a printed circuit board or the like, the solder 7 melts and flows into the hollow part and the lead wire part, which may cause characteristic deterioration.

In order to correct the various defects described above, the applicant of the present application proposed a method of bonding the metal cap 6 using a special photocurable paint containing conductive powder instead of the solder 7.

If such a special photocurable dew-conducting paint is used, it is certainly possible to remove defects caused by heat.
However, in order to connect the completed porcelain capacitor to a printed circuit board by soldering, for example, if heat treatment is performed in a sand chamber at approximately 270°C, the internal air expands and the pressure difference between the inside and outside becomes more than 0.4 atm. Circulation may occur and airtightness may deteriorate. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a cylindrical ceramic capacitor that solves the above-mentioned drawbacks and improves moisture resistance.

To achieve the above object, the present invention includes a cylindrical porcelain element, an inner electrode continuously provided on the inner peripheral surface, one end surface, and a part of the outer peripheral surface of the element, and A step of forming a magnetic capacitive element consisting of an outer electrode provided on the outer peripheral surface, and forming a silane coupling agent layer by immersing the magnetic capacitive element in a solution containing a silane coupling agent, pulling it up, and then drying it. a step of adhering metal caps to both ends of the magnetic capacitive element, and applying a photocurable paint containing conductive powder to at least the boundary areas of the inner and outer electrodes and the metal caps. The present invention relates to a method for manufacturing a ceramic capacitor, which includes a step of forming a conductive paint layer by coating and photocuring.

According to the present invention, since the metal cap is immersed in a solution containing a silane coupling agent and then dried, the metal cap is bonded with a photocurable paint containing conductive powder. It becomes strong due to the action of the porcelain capacitor, and when the completed porcelain capacitor is connected by solder bonding, air circulation will not occur even if heat of 270° C. is applied between the cape sand and the cape. Furthermore, since the silane coupling agent is applied to the entire surface of the element body, it is possible to improve the moisture resistance and electrical characteristics, particularly in the area where the inner electrode and the outer electrode are separated on the inner circumferential surface of the element body. A method of manufacturing a cylindrical ceramic capacitor according to an embodiment of the present invention will be described below with reference to the drawings. In the first embodiment of the present invention, as shown in FIG. An inner electrode 13 is formed on the inner peripheral surface 12, and an outer electrode 15 is formed on the outer peripheral surface 14. In this case, the inner electrode 13 is formed not only on the inner circumferential surface 12 but also on the outer circumferential surface 14 for electrical connection, and this is used as the lead-out portion 13a. Furthermore, of course, separation regions 16 and 17 are provided between the inner electrode 13 and the outer electrode 15 to substantially separate the two. Next, use the silane coupling agent (KBM from Shin-Etsu Chemical Co., Ltd.) shown in Figure 2.
403) in an alcohol solution containing about 6% by weight, and then completely dried.

As a result, the electrodes 13, 15 as shown in FIG.
A silane coupling agent layer 18 is formed on the entire outer peripheral surface of the element body 11. The treatment with the silane coupling agent is preferably performed by immersing the element body 11 in an alcohol solution or aqueous solution containing the silane coupling agent at 1 to 10% by weight. Although substantially the same effect can be obtained by performing this silane coupling agent treatment after ironing the metal cap, treatment before ironing the metal cap is more advantageous in terms of work characteristics. A silane coupling agent is an organic monomer having two or more different reactive groups in its molecule, and chemically bonds with inorganic materials as well as organic materials. For example, y-glycidoxypropyltrimethoxysilane or the like can be used as a silane coupling agent.

Next, as shown in FIG. 4, a metal cap 19 is iron-bonded onto the silane coupling agent layer 18 formed thereon.

For example, the metal cap 19 is made of JIS type 1 SPCC cold rolled steel plate with a thickness of 0.15 mm and an outer diameter of 2.15 mm.
The ribs are formed so that the inner diameter is 1.85 willow and the length is 1.4 willow, and then the lead wire 21 is welded, and after about 1 layer of copper plating, 10% lead: tin is formed. 90% of the plating layer is formed to a thickness of approximately two peaks. Since Figure 4 is illustrated for explanatory purposes, is it a metal handshake? Removed at the time of press-fitting the three-way metal cap, a portion of the metal cap I9 is now wedged into the electrodes 13 and 15. By gluing the metal caps 19 to both ends as described above, both ends of the cylinder are closed and airtightness is improved. However, it is impossible to form the element body 1 into a perfect circle, and there is a gap between the metal cap 19 and the electrodes 13, 15, so as shown in FIG.
A boundary region 201 between each metal cap 19 and the electrodes 13 and 15 is formed. In order to form this photocurable conductive paint layer 22, first, an epoxy polyester photocurable resin (MO-8 manufactured by Sunuresin ■) is used.
...75% by weight sensitizer (MH-5 manufactured by Sunuresin ■)
).・・・． ...1.5% by weight Silver powder of approx. 1.2 m 1.5% by weight - Bon powder ...7
．． A paint consisting of 5% by weight is applied and then cured by irradiation with ultraviolet light for about 1 minute using a 2kW ultraviolet pump.

At this time, the silane coupling agent applied in advance acts on the inorganic materials of the electrodes 13, 15 and the metal cap 19 and the organic material of the conductive paint, increasing the bonding strength of the conductive paint layer 22. Next, as shown in FIGS. 6 and 7, a thermosetting resin layer 23 such as epoxy resin is formed over the entire structure except for the lead wires 21.

This resin layer 23 is formed by curing, for example, by heating at 150oC for 3 minutes.
2, and the conductive paint layer 22 is firmly bonded by the silane coupling agent.
Even if the air inside expands and a pressure difference occurs, no air circulation occurs through the conductive paint layer 22, and no pinholes or the like occur in the thermosetting resin layer 23. The cylindrical ceramic capacitor made by the method described above is mounted on a printed circuit board or the like and then connected to a wiring conductor by a solder bonding method or the like. At this time, for example, even if the sand is heated to 270° C. and the pressure difference between the inside and outside becomes 0.4 atmospheres or more, airtightness by the guide paint layer 22 can be sufficiently maintained. Further, according to this method, the silane coupling agent layer 18
Since it is simultaneously applied to the separation regions 16 and 17, it is possible to improve the insulation and moisture-proof properties of the surface by the dried silane coupling agent layer 18 without providing an independent surface treatment step. Furthermore, according to this method, it is not necessary to bond the metal cap 19 with solder or the like, so that defects caused by solder bonding can be removed. FIG. 8 shows a second embodiment of the invention. The configurations and functions of the components indicated by numerals 11 to 23 in FIG. 8 are as follows.
Since they are substantially the same as those with the same reference numerals in FIGS. 7 to 7, their explanation will be omitted. In this embodiment, electrodes 13, 15
For an element with an outer diameter of 1.8 ribs, 0.03 to 0.05
It has a plurality of protrusions 24 on the side, and the diameter of the inscribed circle of the protrusions 24 is 1.75 mm, and the metal cap 19 on the side is elastically deformed and attached, so that an extremely stable bonding state is achieved. It has become. However, due to the plurality of protrusions 24, corresponding gaps are created, and the photocurable conductive paint also penetrates into these gaps.
Since ultraviolet rays are not irradiated to this gap, in this example, a thermosetting agent (MH manufactured by Sunurenji Co., Ltd.) was added to the photocurable guide paint.
-34) is added in an amount of 1% by weight, and is cured by heat treatment at about 150° C. for about 3 minutes to form the thermosetting resin layer 23, thereby obtaining the conductive paint layer 22. According to the second embodiment described above, it is possible to obtain the same effects as in the first embodiment, and it is also possible to reliably attach the metal cap 19, and furthermore, the bonding by the conductive paint layer 22 can be achieved. will also become stronger.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and can be further modified. For example, the metal cap may be treated with a silane coupling agent after being delivered to Europe. Further, the electrodes 13 and 15 may be plated electrodes. Further, wax treatment or the like may be further performed on the resin layer 23.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional ceramic capacitor, Figures 2 to 7
The figures show the first embodiment of the present invention in the order of steps; FIG. 2 is a cross-sectional view of the Qin body after electrode formation; FIG. 3 is a cross-sectional view showing the state after being treated with a silane coupling agent; Figure 4 is a cross-sectional view showing the state after the metal cap is bonded, Figure 5 is a cross-sectional view showing the state after the formation of the lead paint layer, Figure 6 is a cross-sectional view of the completed capacitor, and Figure 7 is Figure 6. FIG. 8 is a sectional view showing a capacitor according to a second embodiment of the present invention. In the symbols used in the drawings, 11 is a ceramic body, 13 is an inner electrode, 15 is an outer electrode, I6 and 17 are separation regions, 18 is a silane coupling agent layer, 19 is a metal cap, and 20 is a boundary region. , 22 is a photocurable conductive paint layer, 2
3 is a thermosetting resin layer. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A cylindrical porcelain element, an inner electrode continuously provided on the inner peripheral surface, one end surface, and a part of the outer peripheral surface of the element, and an outer electrode provided on the outer peripheral surface of the element. forming a silane coupling agent layer by immersing the ceramic capacitive element in a solution containing a silane coupling agent, pulling it up, and then drying it; Fitting metal caps to both ends of the element, and applying a photocurable paint containing conductive powder to at least the boundary areas between the inner and outer electrodes and the metal caps, and photocuring the coating. and forming a conductive paint layer by.