JPH03145812A - Electronic component - Google Patents

Abstract

PURPOSE:To preclude a gap at the time of soldering from being bridged by the solder by providing a sheath made of an insulator or a dielectric substance, and covering at least a gap part of an outer electrode. CONSTITUTION:A strip shape sheath 9 made of a heat resistant insulator or dielectric substance is provided respectively to the end of an external electrode 4b in the middle or around the end of cap terminals 6a, 6b so as to cover annular gaps 5a, 5b of outer electrodes 4a-4c, respectively. Thus, even when the size of the gaps 5a, 5b is small, the possibility of bringing gaps 5a, 5b at the time of soldering by a solder is precluded since the part is covered with the sheath 9.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic component, such as a piezoelectric oscillator with built-in load capacitance, which has a plurality of external electrodes separated by gaps on its outer surface. .

[Conventional technology]

Conventional examples of this type of electronic component are shown in FIGS. 7 and 8.

This electronic component 2 is an example of a piezoelectric oscillator with built-in load capacitance, and is made of a dielectric material and has a rectangular cylindrical case 3 with open ends. Divided external electrodes (also called capacitor electrodes) 4a to 4c are formed.

Both ends of the case 3 are covered with metal cap terminals 6a and 6b, respectively, and both are electrically connected to external electrodes 4a and 4c at both ends, respectively.

Further, in this example, a piezoelectric resonant element 7 is housed in the case 3 as an electronic component element, and both ends thereof are conductively bonded to the respective cap terminals 6a and 6b by a conductive paste 8.

More specifically, this piezoelectric resonant element 7 is of an energy trapping type that utilizes thickness shear vibration, and has electrodes 72 and 73 on both the front and back sides of a strip-shaped piezoelectric substrate 71 in the center. The electrodes 72 and 73 are connected to the cap terminal 6a and the cap terminal 6b by conductive paste 8, respectively.

Since a capacitance C is formed between the external electrodes 4a and 4b and between the external electrodes 4b and 40, the equivalent circuit of the electronic component 2 is shown by the solid line in FIG. Therefore, such electronic component (piezoelectric oscillator with built-in load capacitance) 2 is suitable for use in, for example, a Colpitts type oscillation circuit.

[Problem to be solved by the invention]

However, in the electronic component 2 described above, when soldering it to a board etc., it is soldered at the cap terminals 6a, 6b and the middle external electrode 4b, but the dimensions of the gaps 5a, 5b Since the diameter is small, for example, 1 mm or less, the external electrode 4a is
4b and between the external electrodes 4b and 40 (that is, the gaps 5a, 5b) may be bridged (short-circuited).

Furthermore, there is also a risk of poor insulation between the external electrodes 4a to 40 and short circuits due to migration of the electrical material. Therefore, there is a problem in terms of credibility.

Moreover, in order to prevent the above-mentioned insulation defects, etc., high processing accuracy of the external electrodes 4a to 4C (in other words, of the gaps 5a and 5b) is required, which also poses a problem in terms of productivity.

In particular, when increasing the capacitance between the external electrodes 4a to 40, the gaps 5a and 5b must be made smaller, so that the above-mentioned problems become even more pronounced.

Therefore, the main object of the present invention is to improve the above-mentioned points and provide an electronic component with excellent reliability and productivity.

[Means to solve the problem]

To achieve the above object, the electronic component of the present invention is, simply put, characterized in that it is made of an insulator or dielectric and is provided with an outer cover that covers at least the gap portion of the external electrode as described above.

[Effect]

The above-mentioned outer cover prevents bridging between external electrodes, poor insulation between external electrodes, and migration of electrode material during soldering.

〔Example〕

FIG. 1 is a perspective view showing an electronic component according to an embodiment of the present invention. FIG. 2 is a sectional view of the electronic component of FIG. 1. The same reference numerals are given to the same or corresponding parts as in the example of FIGS. 7 and 8, and the differences from the conventional example will be mainly explained below.

In the electronic component 2a of this embodiment, a band-shaped outer cover 9 made of a heat-resistant insulator or dielectric is placed so as to cover the annular gaps 5a and 5b of the external electrodes 4a to 4c as described above, respectively. They are provided from near the ends of the cap terminals 6a and 6b to near the end of the middle external electrode 4b.

The reason why the outer cover 9 is made heat resistant is that the soldering can withstand the heat of time.

By doing as described above, even if the gaps 5a and 5b are small, since those portions are covered with the outer sheath 9, there is no possibility that the gaps 5a and 5b may be bridged by solder during soldering.

Further, since the gaps 5a and 5b are covered with the outer cover 9, poor insulation and insulation deterioration between the external electrodes 4a to 40 are prevented.

In addition, the gaps 5a and 5b are covered with an outer sheath 9, and this outer sheath 9 blocks moisture.
Migration of the electrode material is effectively prevented.

As a result, the reliability of this electronic component 2a is improved.

In addition, as a result of obtaining sufficient insulation reliability between each of the external electrodes 4a to 40 as described above, there is a margin in the machining accuracy of the gaps 5a and 5b, which increases the productivity (mass production) of this electronic component 2a. It also improves.

In particular, when it is desired to obtain a large capacitance between each of the external electrodes 4a to 40, or when a material with a low dielectric constant is used for the case 3, the dimensions of the gaps 5a and 5b can be increased by using laser processing or the like. Although it is necessary to make it very small, in such a case the effect of providing the above-mentioned outer cover 9 becomes even more significant.

Note that the coating method for the outer cover 9 is arbitrary.

The shape and area of the outer cover 9 may be arbitrary as long as it covers at least the gaps 5a and 5b of the external electrodes 4a to 4c.

For example, unlike the embodiments of FIGS. 1 and 2, external electrodes 4a, 4c are provided between cap terminals 6a, 6b and jacket 9.
The cap terminals 6a, 6b may be partially exposed, or the cover 9 may cover a portion of the cap terminals 6a, 6b to such an extent that soldering thereof is not hindered.

Alternatively, as in the electronic component 2b shown in FIG. 3, not only the gaps 5a and 5b but also the entire external electrodes 4a to 4c may be widely covered with the outer cover 9. However, in this case, soldering is unnecessary. Assume that a part of the middle external electrode 4b is exposed, for example, as shown in the figure.

Furthermore, the external electrodes 43 to 4C may be formed only on a specific side surface instead of being formed on all four sides of the case 3 as described above, for example, as in the electronic component 2c in FIG.
may be formed only on one side with a narrow gap 5a, 5b, in which case at least the external electrodes 4a to 4
It is sufficient to cover the gaps 5a and 5b with the outer sheath 9 on the surface where c is formed.

In the embodiment shown in FIG. 3, in order to eliminate the vertical directionality, it is preferable to provide the exposed portions of the external electrodes 4b on both the upper and lower sides. Similarly, in order to eliminate the vertical directionality in the embodiment of FIG. 4, it is preferable to provide the external electrodes 4a to 4c and the outer cover 9 on both the upper and lower sides.

Further, although the above examples have all been explained using case 3, the present invention is not limited thereto, and can be applied to other types of electronic components, for example, a bonded type as shown in FIG. Can be applied.

That is, in the electronic component 2d of this embodiment, on both the front and back surfaces of a square plate-shaped piezoelectric resonant element 7 having an electrode structure as shown in FIG.
Protective substrates 13a and 13 made of an insulator or dielectric
It has a rectangular chip-shaped electronic component main body 10 which is made by bonding two parts b together with an adhesive 11, leaving a cavity 12 in the central vibrating part.

External electrodes 4 are provided at both left and right ends of the electronic component main body 10.
a and 4C are formed to be electrically connected to the electrodes 72 and 73 of the internal piezoelectric resonant element 7, respectively, and gaps 5a and 4C are formed between the inner and outer electrodes 4a and 4c. 5b and external electrode 4b.
is formed.

In this example, each of the external electrodes 4a to 4C serves as both a terminal electrode and a capacitor electrode, and is applied, for example, by a film forming method such as sputtering.

An annular gap 5 between the external electrodes 4a to 40
a and 5b, and each external electrode 4a to 4
In order not to interfere with soldering to C, an outer cover 9 similar to that described above is provided.

The equivalent circuit of the electronic component 2d of this embodiment is also shown by the solid line in FIG. 9, and since the outer cover 9 is provided, the same effects as in each of the above embodiments can be obtained.

Further, in any of the above embodiments, by coating the outer cover 9 with a dielectric material, the capacitance between the external electrodes 4a to 40 can be increased. Alternatively, by adjusting the dielectric constant of the outer sheath 9 or adjusting the area coated with the outer sheath 9, the shapes of the external electrodes 4a to 4C can be kept as they are, and the static electricity between the external electrodes 4a to 40 can be reduced. You can also make fine adjustments to the capacity.

Further, other functional materials can be provided on the outer cover 9 in the embodiment shown in FIG. 3, or on the open side of the case 3 in the embodiment shown in FIG. 4, to provide other functions. . For example, if a resistor is provided across the camp terminals 6a and 6b, the equivalent circuit will include a resistor R shown by a chain double-dashed line in FIG.

Also, the number of external electrodes (number of divisions) is 3 as on each side above.
The number is not limited to 2 or more, but is arbitrary as long as it is 2 or more.

Further, the electronic component element is not limited to the piezoelectric resonant element 7 as described above, and may be other than the piezoelectric resonant element 7.

〔Effect of the invention〕

As described above, according to the present invention, since the outer cover is made of an insulator or dielectric and covers at least the gap portion of the external electrode, there is no fear that the gap portion may be bridged by solder during soldering. In addition, poor insulation between external electrodes, insulation deterioration, migration, etc. are prevented, so the reliability of the electronic component is improved.

Further, as a result of obtaining sufficient insulation reliability between the external electrodes as described above, there is a margin in the machining accuracy of the gap, so that the productivity of the electronic component is also improved.

Additionally, if the electronic component is square, there is generally a risk that the external electrode will break at the corner due to contact with other objects, etc., but if an outer cover such as the one described above is provided, this can be avoided. ,
Since this has a protective effect, such electrode breakage can also be prevented.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an electronic component according to an embodiment of the present invention. FIG. 2 is a sectional view of the electronic component of FIG. 1. FIGS. 3 and 4 are perspective views showing electronic components according to other embodiments of the invention, respectively. Figure 5 shows
FIG. 7 is a sectional view showing an electronic component according to still another embodiment of the present invention. 6 is a plan view of the piezoelectric resonant element portion in FIG. 5. FIG. FIG. 7 is a perspective view showing an example of a conventional electronic component. FIG. 8 is a sectional view of the electronic component of FIG. 7. FIG. 9 is an equivalent circuit diagram of the electronic components shown in FIGS. 1 to 5, 7, and 8. 2a to 2d...Electronic component according to the example, 3...Case, 4a to 4c...External electrode, 5a, 5b...Gap, 6a, 6b...Cap terminal, 7...Piezoelectricity Resonant element (electronic component element), 9... Outer cover, 10... Electronic component body. Figure 1 Figure 2

Claims (3)

[Claims] (1) Consisting of a square chip-shaped electronic component body, a plurality of external electrodes formed on the outer surface of the electronic component body with gaps between them, and an insulator or dielectric material, at least each of the above-mentioned external electrodes. An electronic component characterized by comprising: an outer cover that covers a gap portion. (2) The electronic component according to claim 1, wherein the electronic component main body is formed by bonding protective substrates made of an insulator or dielectric material to both the front and back surfaces of a plate-shaped electronic component element using an adhesive. (3) A rectangular cylindrical case made of dielectric material and open at both ends,
An external electrode formed on at least one outer surface of the case, which is divided into two or more parts by a gap in the length direction of the case, and a cap terminal that is respectively placed on both ends of the case. one electrically connected to both ends of the divided external electrodes, and an electronic component element housed in the case, both ends of which are electrically connected to each of the cap terminals. 1. An electronic component comprising: an outer cover made of an insulator or a dielectric and covering at least a gap portion of the external electrode.