JP3376626B2 - Dip type electronic components - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dip type electronic component. Specifically, the present invention relates to a dip-type electronic component in which an exterior resin portion is formed by dipping. 2. Description of the Related Art There are a wide variety of electronic components such as ceramic filters, ceramic capacitors, resistance networks, and ICs. And terminals. In many of these electronic components, the electronic component body and terminals are coated with an exterior resin. Conventionally, as these exterior resins, thermosetting resins having insulating properties have been used because it is necessary to maintain the insulating properties of the electronic component body. However, an insulating resin such as an epoxy resin, which has been conventionally used for the exterior of electronic components, cannot prevent surges and noises from entering the electronic component body from the outside through terminals of the electronic components. Was. Also, depending on the type of electronic component, electric charges are generated from the electronic component body itself due to a temperature change or the like, such as a piezoelectric component, and a high voltage is applied to the electronic component body. These noises, high voltage loads, and the like have problems in that the deterioration of the electronic component body is accelerated and the characteristics of the electronic component are changed. [0004] For example, consider the case where the electronic component body is a dip type ceramic filter made of a piezoelectric ceramic plate. 1 (a) and 1 (b) are cross-sectional views of a typical ceramic filter 1. This ceramic filter 1 has electrodes 3 of a predetermined pattern formed on both sides of a piezoelectric ceramic plate 2 and is soldered or the like. Each electrode 3
After the terminals 4 are respectively connected to the terminal connection portions 3a, the piezoelectric ceramics plate 2 is covered with an exterior resin portion 5 such as an epoxy resin by dip molding. The piezoelectric ceramic plate 2 corresponding to the electronic component body generally has a P
such as bTiO ₃ -PbZrO ₃ ceramics have been widely used. Reference numeral 6 denotes a cavity formed in the vibration region 7. In such a ceramic filter 1, when the piezoelectric ceramic plate 2 is once brought to a high temperature state (FIG. 2 (a)) and then returned to room temperature (FIG. 2 (b)), as in the case of soldering. , Pyroelectric charges 8 are generated on the surface of the piezoelectric ceramic plate 2. This pyroelectric charge 8
As shown in FIG. 2B, an electric field Ep in the direction opposite to the polarization direction P of the piezoelectric ceramic plate 2 is generated. The electric field Ep changes the degree of orientation of spontaneous polarization in the piezoelectric ceramic plate 2, and the ceramic filter 1 There is a disadvantage that the resonance frequency and the anti-resonance frequency change. In order to prevent this, a piezoelectric ceramic plate 2 having a small insulation resistance must be used, and there is a problem that there is less room for selecting a piezoelectric material. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object the purpose of invading from outside through terminals of electronic parts and the like. An object of the present invention is to prevent a characteristic change or deterioration of an electronic component due to a high voltage load generated by surge, noise, or pyroelectric charge. A dip-type electronic component according to the present invention is characterized in that an exterior resin portion is dip-molded with a dip resin material having a varistor function. In the dip-type electronic component according to the present invention, since the exterior resin portion is formed of a dip resin material having a varistor function, a varistor element is connected between electrodes or terminals of the electronic component. It has the same effect as. That is, noise or surge that has entered from the terminal of the electronic component or the like is absorbed by the exterior resin portion having a varistor function, and it is possible to prevent the noise or surge from flowing into the electronic component body. Also, even if pyroelectric charges or the like are generated in the internal piezoelectric ceramics and a high voltage is generated, when the voltage reaches the varistor voltage of the exterior resin portion, the resistance of the exterior resin portion rapidly decreases, An electric current flows through the exterior resin portion so as to cancel the electric field due to the pyroelectric charge, thereby preventing a high voltage load from being applied to the internal electronic component body. On the other hand, the exterior resin portion having the varistor function maintains insulation (high resistance) when a high voltage or the like is not applied. Retain the nature. DESCRIPTION OF THE PREFERRED EMBODIMENTS A dip type electronic component according to the present invention
An exterior resin portion is formed by dip molding a resin material having a varistor function on the surface of the electronic component body. The resin material for the dip is made of, for example, a thermosetting resin (base resin) such as an epoxy resin or a ZnO-based or SrTi-based resin.
It is obtained by kneading and dispersing varistor powders such as O ₃ and SiC. If the exterior resin portion of the electronic component is formed by dip molding with such a resin material having a varistor function, the same effect as connecting the varistor element between the electrodes or terminals of the electronic component body can be obtained. Therefore, noise and surge that enter from the outside via the terminal of the electronic component can be absorbed by the exterior resin portion, and the electronic component body can be protected from the noise and surge. Further, it is possible to prevent electric charges generated from the electronic component body and a high voltage load caused by the electric charges. For example, in the case of a dip type ceramic filter 1 as shown in FIGS. 1 (a) and 1 (b), an electrical connection is made between the terminals 4 and 4 by an exterior resin portion 9 formed by dip molding with a dip resin material having a varistor function. However, in a normal state, the exterior resin portion 9 having a varistor function has insulation properties and fulfills the original purpose of the exterior resin portion. However, when pyroelectric charges are generated on the surface due to thermal shock due to soldering, when the voltage due to the pyroelectric charges reaches the varistor voltage of the varistor powder, the resistance of the exterior resin portion 9 (that is, the varistor powder) decreases sharply, Since charges move inside the exterior resin portion 9 so as to cancel the electric field due to the electric charges,
Depolarization of spontaneous polarization due to pyroelectric charge can be prevented. By using a resin material having a varistor function as a resin material for dip of an electronic component as described above,
In addition to maintaining the original purpose of the exterior resin portion, the insulating property, it is possible to prevent a change in the characteristics of the electronic component body due to a load such as noise or voltage on the electronic component body. Moreover, unlike the case where individual varistor elements are connected to the electronic component, the external shape of the electronic component does not increase, and the cost can be reduced. Specific Examples Hereinafter, as specific examples of the present invention, a method of manufacturing a resin material for coating in which ZnO-based varistor powder is dispersed in a thermosetting epoxy resin, and using the resin material for coating. Next, a ceramic filter having an exterior resin portion formed will be described. Further, a ceramic filter having an exterior resin portion formed using a coating resin material according to a conventional example was manufactured, and changes in resonance and anti-resonance frequencies of the ceramic filters of the example and the conventional example were measured. First, an embodiment of the present invention will be described.
As the ceramic powder having a varistor function, 9
Sb ₂ O ₃ and Mn are added to ZnO having a purity of 9.9% or more.
A ZnO-based varistor manufactured by a so-called solid phase method was used as a raw material by adding O ₂ and CoO. in this case,
The firing of the raw material powder was performed at 1000 ° C to 1100 ° C.
However, at the time of firing, the raw material powder was fired as it was, then pulverized, and sieved to particles having a certain particle size or less. This powder was used as a raw material varistor powder. An epoxy resin having a thermosetting temperature of 107 ° C. was used as the thermosetting resin serving as the base resin. Then, 80 parts by weight of the varistor powder and 20 parts by weight of the epoxy resin are mixed, a ketone solvent is added as a curing agent, silica is added as a filler, and a simple mixing is performed with a stirring blade. Was performed to obtain a resin material for dip. Thereafter, the resin material for dip was kneaded by a roll. The filter element is (Pb _0.99 La _0.01 ) (Ti _0.50 Zr _0.50 ) O ₃ +0.2
A piezoelectric ceramic plate made of wt% Cr ₂ O ₃ was subjected to a polarization treatment, and an electrode pattern was formed on the surface by baking an Ag paste or the like. After soldering a terminal to the electrode of the filter element, the filter element was dipped in the resin material for dipping to form an exterior resin portion. Thereafter, the coating resin material was cured in a 120 ° C. temperature bath. Conventional Example On the other hand, as a conventional example, a resin material for dip of 100 parts by weight of an epoxy resin containing no varistor powder was prepared, and an exterior resin portion was dip-molded on a filter element under the same conditions as in the example. Measurement Results The ceramic filter of the embodiment and the ceramic filter of the conventional example thus prepared were placed in a 250 ° C. temperature bath for 3 minutes to perform a heat treatment, taken out of the temperature bath, and left at room temperature for 2 hours. did. At this time, the change amount ΔFr of the resonance frequency and the change amount ΔFa of the antiresonance frequency before and after heating were examined for the example and the conventional example, respectively.
Table 1 shows the measurement results. [Table 1] As can be seen from Table 1, according to the present embodiment, the resonance of the ceramic filter is smaller than that of the conventional example.
The amounts of change ΔFr and ΔFa of the anti-resonance frequency were both very small. In the above embodiment, the case where the present invention is applied to a ceramic filter has been described. However, the present invention can be used for all electronic components in which an exterior resin portion is dip-formed with a dip resin material. For example, when used for a ceramic capacitor, the exterior of the capacitor material can be protected by applying the dip resin material of the present invention, even if noise having a voltage higher than the withstand voltage occurs. As for various other types of electronic components, it is of course possible to protect the electronic component body from surges and noises by using a resin material for dips having a varistor function. According to the present invention, since the exterior resin portion is formed by dip molding with a dip resin material having a varistor function, the original function as the exterior resin portion of the electronic component and the function of the varistor are maintained. It is possible to obtain a multifunctional electronic component having the same function. Therefore, noises and surges invading from the outside through terminals of the electronic parts are absorbed by the exterior resin portion,
Electronic components can be protected from noise and surge.
In addition, charges such as pyroelectric charges generated from the electronic component body and a high-voltage load due to the charges can be removed by the exterior resin portion. Therefore, the life of the electronic component of the dip type can be greatly extended. Further, it is possible to prevent a change or deterioration of the characteristics of the electronic component body due to a load such as noise. Further, since the electronic component body can be protected from noise, high-voltage load, and the like by the exterior resin portion, there is an advantage that the range of choice of materials used for the electronic component body can be expanded.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are cross-sectional views showing a dip type ceramic filter according to one embodiment of the present invention and a conventional example. FIGS. 2A and 2B are explanatory views showing a mechanism of generating pyroelectric charges on a piezoelectric ceramic plate. [Description of Signs] 1 Ceramic filter 2 Piezoelectric ceramic plate 4 Terminal 9 Exterior resin part

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasunobu Yoneda 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-51-100298 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01C 1/02 H01C 7/10 H03H 9/02

Claims (1)

(57) [Claim 1] An electronic component of a dip type, wherein an exterior resin portion is dip-formed with a dip resin material having a varistor function.