JPH08265079A - Chip filter - Google Patents

Abstract

PURPOSE: To mount the filter onto a printed circuit board with high density by providing RC, LC or RLC function to the filter in a very small form of one chip. CONSTITUTION: The chip RC filter 10 is provided with one or two internal electrodes 12 or over, a bare chip 11 made of a ceramic dielectric body formed so that an internal electrode 12 appears to any of both chip ends opposite to each other, a resistance layer 13 provided from the one end to the other end of the surface of the bare chip 11 so as to be opposite via the internal electrode 12 and the ceramic dielectric body, and a couple of terminal electrodes 14, 15 baked to be conductive to one end of the internal electrode 12 and the resistive layer 13 at both ends of the bare chip 11 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type filter mountable on the surface of a printed circuit board. More specifically, the present invention relates to a chip type filter suitable for a low pass filter, a high pass filter and other filters.

[0002]

BACKGROUND OF THE INVENTION Thick film circuit boards have been manufactured commercially since the early 1950s. This circuit product was based on a network of resistors formed by screen printing on a ceramic substrate. The resistor of this circuit had a carbon-based composition, the conductor was Ag, and the substrate was alumina or steatite. If the substrate is made of BaTiO ₃ or a dielectric having a high relative dielectric constant close to BaTiO ₃ , the substrate that is the dielectric becomes a capacitor, and an RC (resistance value R of the resistor, capacitance C of the capacitor) circuit can be made thereafter. Soon found. It has been found that if the resistor pattern is placed on the capacitor, the capacitance is continuously changed, so that the distributed RC function can be obtained. It has been found that this RC distributed network has properties that are useful as high frequency filters and cannot be obtained with filters composed of separate R and C components. It should be noted that these products used a dielectric ceramic substrate as a capacitor, and were composed of a resistance pattern formed on the surface and a conductor circuit having a structure for connection inside the substrate. Later thin film technology was used for similar purposes. For example, Ta / Ta ₂ O ₅ technology was developed to create RC networks, and Ta ₂ O ₅
As the dielectric, some of these are distributed RC
There was a type feature.

[0003]

However, the conventional R
Since the C filter has a substrate made of a dielectric material and is relatively large, it is not suitable for mounting on a printed circuit board, and has not been formed into a chip shape for surface mounting on a substrate. The object of the present invention is to realize RC, LC in a very small form of one chip.
A chip-type filter having a function of (inductance L of inductor, capacitance C of capacitor) or RLC (resistance value R of resistor, inductance L of inductor, capacitance C of capacitor) and which can be mounted on a printed circuit board at high density is provided. To provide.

[0004]

As shown in FIGS. 1 and 2, a first chip-type RC filter 10 of the present invention is provided with one or more internal electrodes 12 inside the chip and face each other. A bare chip 11 made of a ceramic dielectric formed so that the internal electrode 12 appears at either one of both ends of the chip, and the internal electrode 12 and the ceramic dielectric are formed from one end to the other end of the surface of the bare chip 11. The resistance layer 13 provided so as to face each other with one end portion of the internal electrode 12 and the resistance layer 13 provided at both ends of the bare chip 11.
And a pair of terminal electrodes 14 and 15 that are baked so as to be electrically connected to each other.

As shown in FIGS. 4 and 5, the second aspect of the present invention is described.
The chip-type LC filter 20 of the
The above-mentioned internal electrode 22 is provided, and the bare chip 21 made of a ceramic dielectric is formed so that the internal electrode 22 appears at either one end of the opposite ends of the chip, and from the one end of the surface of the bare chip 21 to the other. The inductor layer 27 is provided so as to face the internal electrode 22 toward the end portion through the ceramic dielectric, and both ends of the bare chip 21 are baked so as to be electrically connected to the one end portion of the internal electrode 22 and the inductor layer 27, respectively. A pair of terminal electrodes 2
4 and 25 are provided.

As shown in FIGS. 7 and 8, the third aspect of the present invention is described.
The chip-type RLC filter 30 is made of a ceramic dielectric material in which one or more internal electrodes 32 are provided inside the chip and the internal electrodes 32 are formed so as to appear at either one of the opposite ends of the chip. Bare chip 31,
The resistance layer 33 is provided so as to face the internal electrode 32 from the one end to the other end of the bare chip 31 via the ceramic dielectric, and the internal electrode from the one end to the other end of the back surface of the bare chip 31. 32, an inductor layer 37 provided so as to face the ceramic dielectric body 32, and a pair of terminals baked on both ends of the bare chip 31 so as to be electrically connected to the internal electrode 32, the resistance layer 33, and the inductor layer 37, respectively. The electrodes 34 and 35 are provided.

The chip filters 10 to 30 of the present invention are
It is made by a wet laminating method or a dry laminating method. First, a BaTiO ₃ -based or Pb-based dielectric ceramic powder, an organic binder, a plasticizer, and an organic solvent are mixed to prepare a dielectric paste or a dielectric slurry. In the wet lamination method,
This dielectric paste is laminated by a curtain coating method on a ceramic dielectric layer on a base plate and dried, and then a conductive paste is screen-printed on this dielectric layer at intervals and dried to form internal electrodes. To do. 1 internal electrode
In the case of a layer, a dielectric paste is similarly laminated on this. When forming a plurality of internal electrodes, the dielectric layers and the internal electrode layers are alternately repeated and laminated a plurality of times. The laminated body is subjected to binder removal processing and then fired, and a paste serving as a resistor or an inductor is screen-printed on the front surface or the back surface of the sintered body, dried and fired. The sintered body is cut into chips in a unit of a resistor or an inductor so that the internal electrode appears at one end. A conductive paste is applied to both ends of the obtained bare chip and baked to form a pair of terminal electrodes.

In order to manufacture the chip filters 10 to 30 by the dry lamination method, the dielectric slurry is film-dried by a doctor blade method or the like to form a ceramic green sheet, and a dielectric layer made of this green sheet is formed. An internal electrode is formed on the upper electrode similarly to the wet lamination method. When the internal electrode has one layer, a dielectric layer made of a green sheet is similarly laminated thereon. When forming a plurality of internal electrodes, the dielectric layers and the internal electrode layers are alternately repeated and laminated a plurality of times. Thereafter, the laminated body is fired, the resistance layer or the inductor layer is formed, and the sintered body is made into chips in the same manner as the wet lamination method, and finally a pair of terminal electrodes is formed.

First to third chip type filters 10 to 30
In both cases, it is preferable to form the insulating films 16, 26, 36a and 36b on the surfaces of the resistance layers 13 and 33 and the inductor layers 27 and 37. As the insulating film, a film containing SiO ₂ as a main component is preferable. As a method for forming this insulating film, a thick film forming method in which a glass paste is applied and baked, or a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a chemical vapor deposition method (CVD) is used.
Method). In addition, the insulating film 1
6, 26, 36a, 36b are terminal electrodes 14, 15, 24, 2 on bare chips 11, 21, 31 cut into chips.
May be formed after or before forming 5, 34, 35,
Alternatively, it may be formed on the surfaces of the resistance layers 13 and 33 and the inductor layers 27 and 37 of the ceramic sintered body before being cut into chips.

[0010]

The first chip type RC filter 10 has the resistance layer 13
And a resistance circuit including the terminal electrodes 14 and 15, the resistance layer 13, the internal electrode 12, and the chip 1 interposed therebetween.
And a distributed capacitance circuit made of a dielectric material, which is shown by the equivalent circuit in FIG. 3 (a) or FIG. 3 (b).
The second chip type LC filter 20 includes an inductor circuit composed of an inductor layer 27 and terminal electrodes 24 and 25, and a distributed capacitance circuit composed of the inductor layer 27, an internal electrode 22 and a dielectric material of a chip 21 interposed therebetween. And is shown by the equivalent circuit of FIG. 6 (a) or FIG. 6 (b). The third chip type RLC filter 30 includes the resistance layer 3
3 and the terminal electrodes 34 and 35, the inductor layer 37 and the terminal electrodes 34 and 35, the inductor, the resistance layer 33 and the internal electrode 32, and the distributed capacitance formed of the dielectric of the chip 31 interposed therebetween. A circuit and a distributed capacitance circuit composed of the inductor layer 37, the internal electrode 33, and the dielectric material of the chip 31 interposed therebetween are shown in the equivalent circuit of FIG. 9A or 9B.

As shown in FIG. 11, in the case of the RC filter, a desired RC time constant can be obtained by making a notch 18 in a desired length in the resistance layer 13 by laser beam light before or after cutting it into chips. Is obtained. Although not shown, the second
If the notch is similarly made in the resistance layer or the inductor layer of the third chip type filter, the desired RC time constant or L
The C time constant is obtained.

Resistor layers 13, 33 and inductor layers 27,
When the insulating films 16, 26, 36a, 36b are formed on the surface of 37, first, N is used for improving the solder heat resistance of the terminal electrode.
When i plating or Sn plating for improving solderability is applied to the terminal electrodes, the plating does not directly adhere to the resistance layer and the inductor layer, and the resistance value or the inductance value does not change. Secondly, chip type filters 10 to 30
The filter characteristics do not change even if the operating environment is hot and humid.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. <Embodiment 1> As shown in FIGS. 1 and 2, a first chip type RC filter 10 includes a bare chip 11 made of a ceramic dielectric, an internal electrode 12, a resistance layer 13, and a pair of terminal electrodes 14 and 15. Equipped with. This chip type filter 10
Is created by the following method. First, a ceramic dielectric green sheet made of a Pb-based relaxor material is laminated to form a ceramic dielectric layer, and then Ag is formed in a predetermined pattern.
A thick film paste of the system is screen-printed and dried to form a large number of internal electrodes at equal intervals, and all of these internal electrodes are covered with the same size ceramic ceramic layer as described above. Dielectric layers were laminated. As a result, the internal electrodes were sandwiched between the upper and lower ceramic dielectric layers. Next, the laminated body is fired to form a plate-shaped ceramic sintered body having a dielectric layer thickness of 5 to several 100 μm and the internal electrodes 12 incorporated therein, and then a predetermined pattern is formed on the sintered body. The RuO ₂ type thick film paste was screen-printed on the positions corresponding to the internal electrodes and baked. By this, thickness 5 to several 10
The resistance layer 13 of 0 μm was formed. This predetermined pattern consists of individual patterns having the same width as the individual patterns of the internal electrodes and a slightly longer length.

Next, the sintered body was cut into individual resistance layers into chips with a diamond saw, and the obtained bare chips 11 were barrel-polished to expose the internal electrodes on one end face thereof. A conductive paste of Ag-Pd is applied to both ends of the bare chip 11 and baked to form a pair of terminal electrodes 14,
Formed 15. Further, the resistance layer 13 of the bare chip 11
The chip-type RC filter 10 was manufactured by applying a glass paste on the surface of and baking it to form an insulating film 16 containing SiO ₂ as a main component and having a thickness of 5 to several tens of μm.

Example 2 A ceramic sintered body was formed in the same manner as in Example 1, and the RuO ₂ type thick film paste of Example 1 was formed on the ceramic sintered body as shown in FIGS. 4 and 5. Instead of, a thick film paste of ferrite or ferromagnetic material was screen-printed and fired in the same manner as in Example 1. As a result, the inductor layer 27 having a thickness of 5 to several 100 μm was formed. After that, the terminal electrodes 24 and 25 were formed in the same manner as in Example 1, and the insulating film 26 was further formed to fabricate the chip type LC filter 20.

<Example 3> A ceramic sintered body was formed in the same manner as in Example 1, and the resistance layer was formed on the surface of this ceramic sintered body in the same manner as in Example 1 as shown in FIGS. 33 was formed, and the inductor layer 37 was formed on the back surface of the ceramic sintered body in the same manner as in Example 2. After that, in the same manner as in Example 1, the terminal electrodes 34 and 35 are formed, and then the insulating films 36a and 36b are formed, whereby the chip-type RLC is formed.
The filter 30 was produced.

<Embodiment 4> As shown in FIG. 10, R was formed in the same manner as in Embodiment 3 except that two layers of internal electrodes 32 were formed.
The LC chip type filter 30 was produced.

[0018]

As described above, according to the present invention, the resistance layer or the inductor layer formed on the surface of the chip together with the internal electrodes formed inside the chip are used as the constituent elements of the capacitor. It can have a function of RC, LC or RLC in a form, and can be mounted on a printed circuit board with high density. Further, if the resistance layer or the inductor layer is cut into a desired length, a desired RC time constant or LC time constant can be obtained. Furthermore, if an insulating film is formed on the surface of the resistance layer and the inductor layer, the plating does not directly adhere to the resistance layer and the inductor layer during the plating process of the terminal electrode, and even if the environment of use of the chip type filter is high temperature and humidity,
The filter characteristics do not change.

[Brief description of drawings]

FIG. 1 is a central cross-sectional view showing a chip type RC filter according to a first embodiment of the present invention.

FIG. 2 is a fragmentary perspective view of a bare chip after forming the resistance layer.

FIG. 3 is an equivalent circuit diagram thereof.

FIG. 4 is a central sectional view showing a chip type LC filter of Example 2 of the present invention.

FIG. 5 is a fragmentary perspective view of the bare chip after the inductor layer is formed.

FIG. 6 is an equivalent circuit diagram thereof.

FIG. 7 is a central sectional view showing a chip type RLC filter of Example 3 of the present invention.

FIG. 8 is a fragmentary perspective view of the bare chip after the resistance layer and the inductor layer are formed.

FIG. 9 is an equivalent circuit diagram thereof.

FIG. 10 is a central cross-sectional view showing a chip type RLC filter of Example 4 of the present invention.

11 is a perspective view corresponding to FIG. 2 in which a cut is formed in the resistance layer.

[Explanation of symbols]

 10 chip type RC filter 11 bare chip 12 internal electrode 13 resistance layer 14, 15 terminal electrode 16 insulating film 18 cut 20 chip type LC filter 21 bare chip 22 internal electrode 24, 25 terminal electrode 26 insulating film 27 inductor layer 30 chip type RLC filter 31 Bare chip 32 Internal electrode 33 Resistive layer 34, 35 Terminal electrode 36a, 36b Insulating film 37 Inductor layer

Claims (7)

[Claims] 1. A chip having one or more internal electrodes (1
2) is provided, and a bare chip (11) made of a ceramic dielectric formed so that the internal electrode (12) appears at either one of the opposite ends of the chip, and the surface of the bare chip (11) A resistance layer (13) provided so as to face the internal electrode (12) through the ceramic dielectric from one end to the other end, and the internal electrodes (12) at both ends of the bare chip (11). A chip-type filter having one end and a pair of terminal electrodes (14, 15) baked so as to be electrically connected to the resistance layer (13). 2. One or more internal electrodes (2
2) is provided, and a bare chip (21) made of a ceramic dielectric formed so that the internal electrode (22) appears at either one of the opposite ends of the chip, and the surface of the bare chip (21) An inductor layer (27) provided to face the internal electrode (22) through the ceramic dielectric from one end to the other end, and the internal electrodes (22) at both ends of the bare chip (21). A chip-type filter having one end and a pair of terminal electrodes (24, 25) baked so as to be electrically connected to the inductor layer (27). 3. One or more internal electrodes (3
2) is provided, a bare chip (31) made of a ceramic dielectric formed so that the internal electrode (32) appears at either one of the opposite ends of the chip, and the surface of the bare chip (31) A resistance layer (33) provided so as to face the internal electrode (32) and the ceramic dielectric from one end to the other end, and from one end to the other end of the back surface of the bare chip (31). An inductor layer (37) provided so as to face the internal electrode (32) via the ceramic dielectric, one end of the internal electrode (32) and the resistance layer at both ends of the bare chip (31). A chip type filter comprising (33) and a pair of terminal electrodes (34, 35) baked so as to be electrically connected to the inductor layer (37). 4. The chip type filter according to claim 1, wherein the resistance layer (13, 33) is covered with an insulating film (16, 36a). 5. The inductor layer (27,37) is an insulating film (26,36b)
The chip type filter according to claim 2 or 3, which is covered with. 6. A notch (1) having a desired length is formed in the resistance layer (13, 33).
The chip type filter according to claim 1 or 3, wherein 8) is inserted and the RC time constant is set to a desired value. 7. The chip type filter according to claim 2, wherein the inductor layer (27, 37) is provided with a notch having a desired length and the LC time constant is set to a desired value.