JPH08316002A - Electronic component and composite electronic part - Google Patents

Abstract

PURPOSE: To reduce variation in resistance owing to self-heating and thermal wear for higher reliability by forming an electronic element layer in such a manner that it is superposed on the opposed ends of a pair of lower electrode layers, formed on an insulating substrate, and forming a pair of upper electrode layers in such a manner that they are superposed on either end of the electronic element area and the respective lower electrode layers. CONSTITUTION: A pair of lower electrode layers 3 are formed on the surface of a rectangular alumina substrate 1. A resistor layer 2 is filled in between the lower electrode layers by a thick film forming method in such a manner that it is superposed on the opposed ends of the lower electrode layers 3. Upper electrode layers 4 are formed on the resistor layer 2 and lower electrode layers 3 in such a manner that they covers the overlapped portion of the resistor layer 4 and lower electrode layers 3, and that its length is larger than that M of the overlapped portion. Thus both the ends of the resistor layer 2 is sandwiched between the upper electrode layers 4 and the lower electrode layers 3, and the efficiency of radiating heat produced by energization is thereby improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a chip resistor and RC
(Composite Electronic Component of Resistor and Capacitor) The present invention relates to an electronic component such as a chip component or a composite electronic component, and particularly to improvement of an electrode structure thereof.

[0002]

2. Description of the Related Art Conventionally, for example, a general thick film chip resistor has a resistor layer structure as shown in FIG. In the figure, a pair of electrodes 43 is provided on the surface of an alumina substrate 41, and a resistor layer 42 is formed by printing and firing (thick film method) so as to straddle both electrodes 43. As an actual chip component, although not shown, the surface of the resistor layer 42 is glass-coated and external electrodes for connecting to the electrodes 43 are provided.

Further, JP-A-60-2466 of the applicant of the present application
There is also a resistor layer structure as disclosed in No. 02. This resistor structure is shown in FIG. 5, as in the case of FIG. In the figure, a resistor layer 52 is formed on the surface of an alumina substrate 51 by printing and firing, and a pair of electrodes 53 overlapping both ends thereof is provided.

[0004]

However, in the case of FIG. 4 and FIG. 5 described above, the size of the electrode shape is limited due to the restriction of the chip size, and the resistor layer 42 or 52 and the electrode 43 or Since the contact area with 53 is small, there is a problem that the heat dissipation is poor and the temperature rises due to self-heating during use, resulting in unstable resistance and large thermal wear. In particular, in the case of FIG. 4, the resistor layer 42 and the electrode 43
When an attempt is made to improve the heat dissipation by increasing the contact area with, the overlapping length L (see FIG. 4) of both becomes longer,
There is also a problem that the thin portion of the resistor layer 42 corresponding to the overlapping portion occupies a large proportion with respect to the central portion, making it difficult to adjust to a desired resistance value.

Further, even in a thick film circuit component obtained by firing a resistor on an insulating substrate (see JP-A-59-79563 and JP-A-59-18669), the same ones as described above are used. And had such a thermal problem.
An object of the present invention is to solve the above problems and provide an electronic component and a composite electronic component having excellent temperature characteristics.

[0006]

The present inventor has taken the following technical means in the present invention in order to achieve the above technical objects. In the electronic component according to the first aspect of the present invention, an electronic element layer is formed so as to overlap opposite end portions of a pair of lower electrode layers formed on an insulating substrate, and both end portions of the electronic element portion and the pair of lower portions are formed. It is characterized in that a pair of upper electrode layers is formed so as to overlap with each of the electrode layers.

According to a second aspect of the present invention, in the electronic component according to the first aspect, the electronic element layer, the upper electrode layer and the lower electrode layer are formed on the insulating substrate by thick film printing. To do. In the composite electronic component according to a third aspect of the present invention, an electronic element layer is formed so as to overlap with opposite end portions of a pair of lower electrode layers formed on an insulating substrate for printed wiring, and both end portions of the electronic element portion are formed. It is characterized in that an electronic component in which a pair of upper electrode layers is formed so as to overlap with each of the pair of lower electrode layers is mounted on the printed wiring insulating substrate together with other components.

The invention according to claim 4 is the same as claims 1 to 3.
In the electronic component or the composite electronic component according to any one of items 1 to 3, the electronic element layer is a resistor layer and / or a dielectric layer.

[0009]

According to the present invention described in claims 1 to 4, the electronic element layer is formed such that both ends thereof are sandwiched between the lower electrode layer and the upper electrode layer.

[0010]

According to the present invention, both ends of the electronic element layer are sandwiched between the lower electrode layer and the upper electrode layer, so that the size of the electronic element is smaller than that of the conventional one electrode layer. The electrode contact area with the element layer can be greatly expanded. Therefore, the reliability against resistance value instability and thermal wear due to self-heating is improved, and an electronic component and a composite electronic component having excellent temperature characteristics can be obtained. Further, since the electrode contact area can be easily increased, it is not necessary to change the set length or size of the electronic element layer itself. For example, when applied to a chip resistor, there is an advantage that the adjustment accuracy to a desired resistance value is not affected. is there.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electronic component in which a resistor layer as an electronic element layer is formed of a thick film, that is, a so-called thick film chip resistor, will be described below with reference to FIGS. 1 to 3. To do. FIG. 1 shows a state in which the thick film chip resistor of this embodiment is mounted on the surface of a printed wiring board. FIG. 2 shows a laminated structure portion of a resistor layer and electrodes of the same thick film chip resistor as shown in FIG.
Shows a plan view of FIG.

In the figure, a pair of lower electrode layers 3 are provided on the surface of a rectangular alumina insulating substrate 1, and both electrode layers 3 are provided.
The resistor layer 2 is formed by printing and firing (thick film method) so as to straddle the above. The resistor layer 2 is a pair of lower electrode layers 3
It is formed so as to be embedded in the space and cover the opposite ends of the electrode layers. The upper electrode layer 4 is laminated and formed on the resistor layer 2 and the lower electrode layer 3 so as to cover the overlapping portion of the resistor layer 2 and the lower electrode layer 3.
And the lower electrode layer 3 are overlapped with each other longer than the length M. Since the resistor layer 2 is covered with the upper electrode layer 4 in this way, the contact area between the resistor layer 2 and the electrode layer is increased, and therefore the length of the overlapping portion between the resistor layer 2 and the lower electrode layer 3 is increased. There is no need to lengthen M. That is, compared with the conventional case shown in FIG. 4, since the contact length with the lower electrode layer can be shortened while increasing the contact area of the entire electrode layer (M <L), the adjustment accuracy of the resistance value is affected. You don't have to give it. Moreover, since the contact area is increased by the upper electrode layer 4, the length M can be designed to be the minimum, and the length of the resistor layer 2 can be the minimum necessary length according to the desired resistance value. Well, it also contributes to miniaturization of the resistor. Upper electrode layer 4
Is laminated on the lower electrode layer 3 while covering the resistor layer 2, and its end portion is set to have substantially the same size and substantially the same as the end of the insulating substrate 1, so that the length of the overlapping portion of both electrode layers is long. Size can be set to the minimum required size, which does not hinder miniaturization.

A paste containing silver, glass and an organic binder is used for the upper and lower electrode layers 3 and 4.
Further, the present invention is not limited to this, and a conductive resin paste having a firing temperature lower than that of glass may be used, and the conductive material is not limited to silver and may be another metal (for example, gold or aluminum). . In particular, when the conductive material is formed of a paste containing silver and palladium as main components, there is an advantage that it is possible to suppress a possibility that a so-called solder crack will cause an adverse effect when mounting on a circuit board with solder.

The resistor layer 2 is formed by a thick film method in which a paste made of fine particles of a metal oxide such as ruthenium oxide (RuO ₂ ) and glass powder made of SiO ₂ and an organic binder is printed and baked. To be done. A thin film resistor formed by vapor deposition such as a sputtering method may be used for this resistor layer. The coating layer 5 covers the resistor layer 2 and both electrode layers 3 and 4, and is made of a glass or resin overcoat layer in which a part of both ends of the electrode layer is exposed. Trimming adjustment may be performed on the resistor layer 2 with a laser or the like to adjust the resistance value. In that case, a protective layer such as glass that covers the resistor layer 2 before trimming and a glass that covers after trimming may be used. Using a two-layer structure consisting of a protective layer,
An outer coating layer such as glass or resin for marking the resistance value or the like may be used.

An external electrode layer 6 is applied to the overlapping portion of the upper electrode layer 4 and the lower electrode layer 3 over the end face side of the insulating substrate 1 and the rear face side of the substrate. The outer electrode layer 6 has a three-layer structure including an inner electrode layer of silver, a Ni-plated underlayer, and a solder-plated outer electrode layer of Pb-Sn. Further, the external electrode layer 6 may be formed with a two-layer structure of a Ni-plated layer and a solder-plated outer electrode layer. FIG. 1 shows a state in which the chip resistor of this embodiment is mounted on the printed wiring insulating substrate 9. A pair of external electrode layers 6 are formed on the pair of conductor patterns 8 formed by printing on the surface of the printed wiring insulating substrate 9.
Respectively, and the chip resistors are mounted on the insulating substrate 9 by the solder 7.

In the chip resistor having the above structure, the upper electrode layer 4 and the lower electrode layer 3 sandwich the both ends of the resistor layer 2 to secure a sufficient electrode contact area. The heat generation can be sufficiently released to the coating layer 5 side through the upper electrode layer 4 and the lower electrode layer 3 and to the solder 7 side through the external electrode layer 6, so that the heat dissipation efficiency can be improved.

The present invention can be applied not only to the single-element electronic component as in the above embodiment, but also to a multi-element embedded component such as a so-called RC chip component such as a resistor and a capacitor. In that case, a dielectric layer sandwiched between a pair of first and second conductor layers, and a resistor layer similar to that of the above-described embodiment is formed between one of the second conductor layer and the third conductor layer. Every second
If both end portions of the resistance layer are sandwiched between the third conductor layer and the third conductor layer by the two-layer structure of the upper electrode layer and the lower electrode layer as in the above embodiment, the heat dissipation effect can be enhanced.

Further, according to the present invention, the wiring is formed on the glass epoxy substrate or the ceramic substrate and the resistor as in the above embodiment is mounted as one component in the composite electronic component in which a plurality of electronic components are mounted. In this case, it can be applied to, for example, a hybrid integrated circuit component for thick film circuits formed by thick film printing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mounted state of a chip resistor according to an example.

2 is a sectional view showing an electrode structure of a resistor of the chip resistor of FIG.

FIG. 3 is a plan view of FIG. 2;

FIG. 4 is a sectional view showing an electrode structure of a resistor of a conventional chip resistor.

FIG. 5 is a cross-sectional view showing an electrode structure of a resistor of another conventional chip resistor.

[Explanation of symbols]

 1 Insulating Substrate 2 Resistor Layer 3 Lower Electrode Layer 4 Upper Electrode Layer

Claims (4)

[Claims] 1. An electronic element layer is formed so as to overlap opposite end portions of a pair of lower electrode layers formed on an insulating substrate, and both end portions of the electronic element portion are overlapped with each of the pair of lower electrode layers. An electronic component in which a pair of upper electrode layers is formed on the surface. 2. The electronic component according to claim 1, wherein the electronic element layer, the upper electrode layer, and the lower electrode layer are formed on the insulating substrate by thick film printing. 3. An electronic element layer is formed so as to overlap opposite end portions of a pair of lower electrode layers formed on a printed wiring insulating substrate, and both end portions of the electronic element portion and the pair of lower electrode layers are formed. A composite electronic component in which an electronic component in which a pair of upper electrode layers are formed so as to overlap with each other is mounted on the printed wiring insulating substrate together with other components. 4. The electronic component or the composite electronic component according to any one of claims 1 to 3, wherein the electronic element layer is a resistor layer and / or a dielectric layer.