JPH0576164B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a feed-through capacitor in which a lead wire passes through a central through hole of a cylindrical dielectric element.

[Prior Art] A conventional feedthrough capacitor is shown in FIG. As is clear from this figure, the conventional feedthrough capacitor is
The lead wire 1 is passed through the central through hole of a cylindrical dielectric element 3 having electrodes 4a and 4b formed on the inner and outer circumferential surfaces, and a cylindrical case 2 is fitted on the outside of the dielectric element 3. It is constructed by soldering a lead wire 1 and a case 2 to electrodes 4a and 4b on the inner and outer circumferential sides, respectively. Both ends of the case 2 are sealed with insulating resins 6 and 7.

A flange 2a is formed on the case 2, and this feedthrough capacitor is constructed by fitting the case 2 into a through hole formed in the chassis a of an electronic device, and conductively fixing the lower part of the flange 2a with solder b. At the same time, for example, the lead wire 1 is used by connecting it to a signal line.

[Problems to be Solved by the Invention] In the conventional feedthrough capacitor, the case 2 is heated when the case 2 is soldered to the chassis a, and the solders 5, 5 inside the case 2 are thereby melted. Put it away. Then, the volume of the solder 5 increases in the limited space inside the case, and as a result, the molten solder permeates through the gap between the resins 6 and 7 that seal the ends of the case 2, and the lead wire 1 and case 2
There was a problem that the two were short-circuited.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide a feedthrough capacitor in which short circuits between lead wires and a case are less likely to occur.

[Means for Solving the Problems] That is, the gist of the means adopted in the present invention in order to solve the above problems is as follows: A cylindrical dielectric element 3, and an inner peripheral surface and an outer peripheral surface of the dielectric element 3. The electrodes 4a and 4b formed respectively, the lead wire 1 which is passed through the center through hole of the dielectric element 3 and soldered to the electrode 4a on the inner circumferential side, and the lead wire 1 which is fitted to the outside of the dielectric element 3. In the feedthrough capacitor, the case 2 is soldered to the outer peripheral side electrode 4a, and the electrode 4b is soldered to the case 2.
This is a feedthrough capacitor in which porous insulating layers 8, 8 are formed at least at both ends of the capacitor.

[Function] In the feedthrough capacitor of the present invention, the case 2
Since porous insulating layers 8, 8 are formed at least on both ends of the electrode 4b to be soldered, when the case 2 is heated from the outside and the solder 5 therein melts, the molten solder A portion of this is absorbed into the porous insulating layers 8, 8. This prevents the solder from protruding from between the case 2 and the electrode 4b, and prevents a short circuit between the lead wire 1 and the case 2.

[Example] Next, an example of the present invention will be specifically described with reference to FIG.

The cylindrical dielectric element 3 is made of dielectric ceramic, has a conductive film of silver or the like formed on its inner and outer peripheries, and is provided with electrodes 4a and 4b.

Furthermore, porous insulating layers 8 and 9 are formed over the entire circumference of at least both end portions of these electrodes 4a and 4b. The insulating layers 8 and 9 are made by, for example, applying a strip of epoxy resin paint containing filler such as SiO ₂ or TiO ₂ to both ends of the inner and outer peripheries of the dielectric element 3 on which the electrodes 4a and 4b are formed. Apply around the circumference,
It can be formed by heating and baking this at a temperature of 150°C for 30 minutes. In the illustrated embodiment, a total of three porous insulating layers 8, 8, . porous insulating layer 9,9
is formed. Note that it is not necessary to provide the insulating layers 9, 9 on the inner electrode 4a, but in order to prevent molten solder from melting from the through holes of the dielectric element 3 and completely prevent short circuits. The first
It goes without saying that it is desirable to form insulating layers 9, 9 also on the electrode 4a on the inner peripheral side as shown in the figure.

Cream solder is applied to the exposed parts of the insulating layers 8 and 9 of the electrodes 4a and 4b on the inner and outer peripheries of the dielectric element 3, and the lead wire 1 is drawn through the central through hole, and a cylindrical case is placed on the outside. 2 is fitted, and then the cream solder is heated and melted, and the lead wire 1 and the case 2 are soldered to the electrodes 4a and 4b, respectively.

The lead wire has a stopper portion 10 with a larger outer diameter in part, and when the lead wire is drawn through the through hole of the dielectric element 3, the stopper portion 10 partially contacts the through hole of the dielectric element 3. It hits and is stopped.

The case 2 has a through hole 2b in the center of the bottom surface,
It is cap-shaped and has a flange 2a extending outward at its upper edge. This case is fitted onto the outside of the dielectric element 3 by passing the lead wire 1 through the through hole 2.

After the case 2 is soldered to the electrode 4b on the outer peripheral side of the dielectric element 3 in this manner, insulating resins 6 and 7 are covered so as to close the opening at the lower end and the opening at the upper end, respectively. The inside of the case 2 is sealed. As a result, a feedthrough capacitor as shown in FIG. 1 is completed.

For example, as shown in the drawing, this feedthrough type capacitor is constructed by fitting a case 2 into a through hole formed in a chassis a of an electronic device, and conductively fixing the part below the flange 2a with solder b, and forming a dielectric element. The electrode 4b on the outer circumferential side of No. 3 is grounded to the chassis a. Also,
The lead wire 1 is connected to a signal line, and noise sent through both signal lines is removed.

If a temperature of 250°C is applied to a certain type of feed-through capacitor for one minute and 1000 capacitors are actually soldered to a chassis a, the incidence of short circuits is approximately 0.44.
It was %. On the other hand, when 1000 feedthrough capacitors of the same shape to which the present invention was applied according to the embodiment shown in FIG. 1 were soldered to the chassis A under the same conditions, the incidence of short circuits was 0. It was %.

[Effects of the Invention] As explained above, the present invention has the effect of preventing short circuit troubles that occur when the feedthrough capacitor is heated to the melting temperature of the solder, such as when soldering a feedthrough capacitor to a chassis. .

[Brief explanation of drawings]

FIG. 1 is a vertical side view of a feedthrough capacitor according to an embodiment of the present invention, and FIG. 2 is a vertical side view of a conventional feedthrough capacitor. 1... Lead wire, 2... Case, 3... Dielectric element, 4a, 4b... Electrode, 5... Solder, 8, 9...
...Porous insulation layer.

Claims (1)

[Claims] 1. A cylindrical dielectric element 3, and electrodes 4a and 4b formed on the inner and outer peripheral surfaces of the dielectric element 3, respectively;
A lead wire 1 is passed through the central through hole of the dielectric element 3 and soldered to the electrode 4a on the inner peripheral side.
and a case 2 fitted on the outside of the dielectric element 3 and soldered to the electrode 4a on the outer peripheral side, at least both ends of the electrode 4b soldered to the case 2,
A feedthrough capacitor characterized in that porous insulating layers 8, 8 are formed.