JPS63304611A - Through-type capacitor - Google Patents

Abstract

PURPOSE:To obtain a through type capacitor wherein the dielectric is prevented from being damaged around the hole through which the central conductor of the dielectric is inserted, by forming a conductive electrode surface on the inner peripheral wall surface of the hole passing through the dielectric, and electrically connecting the conductive electrode surface to the surface of the central conductor passing through the hole by solder. CONSTITUTION:A central conductor 2 becoming one electrode is inserted through and soldered to the inner periphery of a dielectric 1, and a ground electrode plate 3 which is the other electrode is soldered to the outer periphery. Thereafter, sheath cases 4, 5 consisting of insulators are fitted into the ground electrode plate 3, and to improve the withstand voltage, a filler resin 6 is injected and set up, thereby forming a through type capacitor. The gap ground the central conductor 2 having a thickness of T is filled with a solder 7 to 50% in volume rate. With this, a highly reliable through type capacitor can be obtained wherein the damage of the ceramic dielectric due to a thermal shock is different to occur.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a reliable method for preventing damage to the dielectric material due to differences in thermal expansion coefficients of related members around a central conductor penetrating the dielectric material. Concerning feedthrough capacitors with high performance.

[Conventional technology]

Conventionally, feedthrough capacitors have been made by forming a ceramic dielectric material into a cylindrical shape and providing electrodes on the inner and outer peripheral walls.
For example, this is disclosed in Japanese Utility Model Application Publication No. 57-104446, but there is no mention of the structure of the joint between the center conductor and the dielectric.

[Problem that the invention seeks to solve]

Feedthrough capacitors, in which electrodes are formed on the inner and outer circumferential surfaces of a cylindrical dielectric body and electrode terminals (wires or plates) are attached thereto, have been described in technical literature as mentioned above, but static No special description is found regarding the structure of the joint between the dielectric material for obtaining capacitance and the center conductor passed through a hole drilled in the dielectric material.

Normally, feed-through capacitors using ceramic dielectrics are metalized by applying nickel plating to the inner and outer surfaces of the cylindrical dielectric in advance, and the center conductor and ground electrode plate are soldered and fixed there. are doing. In this case, especially on the center conductor side, if the gap between the cylindrical hole provided in the dielectric and the center conductor is completely filled with solder, if an accelerated life test such as a thermal shock test is performed, When heating, the center conductor has a larger coefficient of thermal expansion than the dielectric, so compressive stress is generated in the radial direction of the dielectric hole, and when cooling, thermal shock is generated such as tensile stress in the radial direction. It will be applied repeatedly,
Eventually, the contact area between the two ends up being damaged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a feedthrough capacitor which prevents damage to the dielectric material around a hole through which a center conductor of the dielectric material is inserted even if thermal shocks due to heating and cooling are applied repeatedly.

[Means for solving problems]

In order to solve the above problems, in the present invention, a conductive electrode surface is formed on the inner circumferential wall surface of a hole penetrating the dielectric, and this conductive electrode surface and the surface of the center conductor penetrating the hole are connected. In feed-through capacitors electrically connected with solder,
The electrical connection was made by filling only 10 to 70% of the volume of the gap existing between the dielectric side conductive electrode surface and the center conductor surface with solder. In fact, in order to perform this kind of work, it is generally necessary to use solder resist, which is widely used when attaching components to a printed circuit board, to fill in areas around the center conductor that you do not want to fill with solder. Just cover it. In addition, in this case, among the related components, the solder (and the solder resist if it remains) is relatively flexible, and the difference in thermal expansion coefficient between the center conductor and the dielectric is small in absolute value. The idea is to absorb the difference in thermal deformation with the solder by deforming the solder.
If it is less than 0%, the electrical connection will become uncertain, and if it is more than 70%, it will not be easy to deform the solder, which is not preferable for the purpose of the invention. For this reason, it is preferable to fill approximately 50% with solder. Note that the solder resist does not show any corrosive properties to related components, so even if it remains, no problem will occur.

[Effect]

The related parts where the problem occurs are the dielectric, the central member,
Solder is somewhere in between, but the center conductor is the strongest, and the dielectric is hard but brittle. Among the kings, solder is relatively flexible and has a lot of plasticity, and is located between the center conductor and the dielectric.
The difference in thermal deformation between the two can be absorbed by plastic deformation. However, even though the solder has plasticity, if the gap between the center conductor and the dielectric is completely filled, the escape area (free surface) for deformation is limited to the upper and lower ends of the thin cylindrical gap. Because of this, it cannot be easily deformed (change in the radial thickness of the cylinder), and the relatively weak dielectric material will be damaged by the large force applied to it.

On the other hand, according to the present invention, when the solder deforms due to its plasticity, there are relatively many places where the solder can escape for deformation, so it can be easily deformed, causing large stress on the dielectric. Therefore, its damage will not occur.

〔Example〕

FIG. 1 is a sectional view of one embodiment of the present invention. Reference numeral 1 denotes a disc-shaped ceramic dielectric (eg, strontium titanate) whose inner and outer peripheral surfaces are metalized with nickel plating or the like, forming a capacitor with the inner and outer peripheral walls serving as electrodes.

A center conductor 2 serving as one electrode is inserted into the inner periphery of the dielectric 1, and a ground conductor plate 3 serving as the other electrode is soldered to the outer periphery. Thereafter, an external case 4.5 made of an insulator is fitted onto the ground electrode plate, and in order to improve voltage resistance, filling resin 6 is injected and solidified to form a feedthrough capacitor. FIGS. 2(a) and 2(b) show cross-sectional views taken along the line A-A' in FIG. has been done. In the example shown in Figures (,), the solder filling locations are approximately semicircular, and in the example shown in Figure (b), the solder filling locations are gradually dispersed. In this figure, 21 is a solder resist coating, and this portion is not soldered. If the portions filled with solder and the portions not filled with solder can be formed without using a solder resist, there is no need to use a solder resist. Third
The figure shows a comparison of heat shock cycle cumulative failure rates when the volume ratio of the solder 7 to the gap of thickness T around the center conductor 2 is 100% and the volume ratio is 50%. The functions and effects of this embodiment are as described above.

Although this embodiment shows an example in which one central conductor is inserted through the dielectric, it goes without saying that the same effect can be obtained even if a plurality of conductors are inserted through the dielectric.

〔Effect of the invention〕

As explained above, according to the present invention, a highly reliable feed-through capacitor that is unlikely to be damaged due to thermal shock of the ceramic dielectric during repeated heating and cooling that occurs in actual use can be achieved by using extremely simple means. can get.

[Brief explanation of drawings]

Figure 1 is a sectional view of one embodiment of the present invention, Figures 2 (a) and (b)
) is a cross-sectional view taken along the line A-A' in Figure 1. Figure (a) shows an example in which the solder filling locations form an almost semicircular shape, and Figure (b) shows an example in which the solder filling locations are gradually dispersed. FIG. 3 is a graph showing a comparison of cumulative failure rates between an embodiment of the present invention and the prior art. 1... Ceramics dielectric, 2... Center conductor, 3...
...Ground conductor plate, 4, 5...Exterior case, 6...Filling hatsumode, 7...Solder, 21...Solder resist.

Claims (1)

[Claims] 1. A conductive electrode surface is formed on the inner peripheral wall surface of a hole penetrating the dielectric, and this conductive electrode surface and the surface of the center conductor penetrating the hole are electrically connected with solder. In the connected feedthrough capacitor, the electrical connection is made by filling only 10 to 70% of the volume of the gap between the dielectric side conductive electrode surface and the center electrode conductor with solder. Feedthrough capacitor. 2. The feedthrough capacitor according to claim 1, wherein a solder resist is applied to the portions not filled with solder. 3. The feedthrough capacitor according to claim 1, wherein approximately 50% of the volume of the gap is filled with solder.