JPH06275466A - Multilayer lc filter and its production - Google Patents

Abstract

PURPOSE:To provide a multilayer LC filter and its production method by which it can be easily mounted on a circuit board by improving the contraction ratio of the bonding part of different materials. CONSTITUTION:Between a first dielectric green sheet 1 and a first magnetic green sheet 3, a second dielectric green sheet 2 and a second dielectric green sheet 4 which have a higher contraction ratio than those of the respective sheets 1 and 3 are prepared and stocked/baked as a whole body, thereby making the contraction ratio of a bonding part 5 almost equivalent to those of a inductor part and a capacitor part. As a result, the projection in the part 5 for bonding different materials can be suppressed, resulting in a multilayer LC filter having a smooth circumferential surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated LC filter which can be easily mounted on a circuit board and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a laminated LC filter, a capacitor portion is provided inside a dielectric porcelain, an inductor portion is provided inside a magnetic porcelain, and a dielectric porcelain and a magnetic porcelain are integrally formed in a laminated body. The capacitor and the inductor are electrically connected to form a lumped constant LC filter, for example. In the case of the lumped constant type LC filter, the input terminal electrode 7 and the output terminal electrode 8 are connected to the facing end surface of the laminate and the peripheral surface continuous with the end surface, and the ground terminal electrode 9 is non-contact with the opposite side surface of the laminate. The terminal electrode 10 is configured.

The laminated LC filter is manufactured by the following method. After mixing the dielectric ceramic raw material powder and calcining,
A green sheet is formed by kneading with an organic binder, and an electrode for obtaining capacitance is formed on the green sheet. Separately from this, magnetic porcelain raw material powder is mixed, calcined, and then kneaded with an organic binder to prepare a green sheet,
A coil conductor is formed on the green sheet. A plurality of the dielectric green sheets are stacked to form a capacitor section, and a plurality of magnetic green sheets are stacked on the dielectric green sheet to form an inductor section. By firing, the capacitor part and the inductor part are connected to each other and are internally provided in the laminated body. An input terminal electrode 7, an output terminal electrode 8, a ground terminal electrode 9 and a non-contact terminal electrode 10 are formed on the end surface and the side surface of the laminated body.

To mount the laminated LC filter on a circuit board, a suction nozzle of an automobile component mounting machine is used. That is, the laminated LC filter is adsorbed under reduced pressure on the surface on which the non-contact terminal electrode 10 is formed, and the input terminal electrode 7, the output terminal electrode 8 and the ground terminal electrode 9 overlap the three lands formed on the circuit board. Mounted and soldered.

[0005]

The laminated body in which the capacitor and the inductor are provided has a dielectric porcelain and a magnetic porcelain integrated with each other.

Although an attempt has been made to approximate the contraction rate of the dielectric green sheet and the contraction rate of the magnetic green sheet, a raw material having a different composition is used at the joint between the dielectric green sheet and the magnetic green sheet. Since it is fired while being in contact, the sinterability of the joint deteriorates and the shrinkage rate decreases, and as shown in FIG.
Therefore, the peripheral surface where the joint is exposed is not flat. Since the ground terminal electrode 9 and the non-contact terminal electrode 10 are formed after the joining portion 5 projects, the suction nozzle of the automatic component mounting machine decompresses the surface on which the non-contact terminal electrode 10 is formed to convey the surface. Then, there is a problem that the vacuum suction becomes insufficient and a transport error may occur. Furthermore, when such a laminated LC filter is mounted on a circuit board, one end of the mounting surface of the laminated LC filter is lifted from the circuit board and cannot be mounted flat. There is also a problem that the laminated LC filter mounted in such a tilt lacks reliability in terms of soldering strength and vibration.

The object of the present invention is to improve the shrinkage ratio of the joint portion 5 of different materials and solve the above problems.
It is to provide a C filter and a manufacturing method thereof.

[0008]

The gist of the means for solving the problems is, firstly, a laminated LC filter in which a dielectric ceramic and a magnetic ceramic are laminated and integrally formed. As shown, the first dielectric porcelain forming the main part of the dielectric porcelain and the first magnetic porcelain forming the main part of the magnetic porcelain each have a second shrinkage ratio different from that of the main part. The dielectric ceramic and the second magnetic ceramic are bonded via a thin layer, and the bonding portion 5 between the dielectric ceramic and the magnetic ceramic is also provided.
Is a laminated LC filter in which the exposed peripheral surface is smooth,
Secondly, in the method for manufacturing the laminated LC filter, a step of forming a first dielectric green sheet 1 by mixing and calcining a dielectric ceramic raw material powder, and a capacitance on the dielectric green sheet. A step of forming a capacitor unit green sheet on which an acquisition electrode is printed, a step of mixing and calcining a magnetic substance porcelain raw material powder to form a first magnetic substance green sheet 3, and a step of forming the magnetic substance green sheet A step of forming a green sheet for an inductor section on which a coil conductor is printed, a step of integrally pressing the green sheet to form the capacitor section and the inductor section, and forming a terminal electrode on the end face of the laminate. In the method for manufacturing a laminated LC filter, the method comprises: calcining at a temperature lower than a calcining temperature of a raw material powder forming the first capacitor part green sheet. And the step of forming the second magnetic green sheet 4 that is calcined at a temperature lower than the calcining temperature of the raw material powder that constitutes the first inductor green sheet. When,
After stacking the first capacitor green sheets, a second dielectric green sheet 2 calcined at a low temperature is stacked, and then a second magnetic green sheet 4 calcined at a low temperature is stacked. The method further includes the step of stacking and stacking the first green sheet laminate for the inductor section.

[0009]

When the laminated body is fired, green sheets having a shrinkage ratio larger than that of the respective green sheets are arranged at the portions where the dielectric green sheets and the magnetic green sheets are contact-joined, and the layers are laminated and fired. Although the sinterability is reduced and the shrinkage rate of the joint portion 5 is reduced in the portion where different materials come into contact with each other, a green sheet having a large shrinkage rate is previously attached to the joint portion 5.
Since it is arranged in the above, the contraction rate of the joint portion 5 can be made substantially equal to the contraction rates of the inductor section and the capacitor section. As a result, it is possible to obtain the function of preventing the protrusions from being formed in the joint portion 5 of different materials.

[0010]

EXAMPLE A dielectric green sheet was prepared by the following procedure. TiO ₂ , NiO, and CuO each 10
After mixing at a mixing ratio of 0, 10 and 5 parts by weight, the mixture was calcined at a temperature of 800 ° C. and crushed to obtain a first mixture.
Of the dielectric calcination powder. The same mixture was calcined at a temperature of 760 ° C. and crushed to obtain a second dielectric calcined powder. An organic binder is added to each of the two types of calcined dielectric powders and kneaded to form a slurry, and a dielectric green sheet having a thickness of 70 μm is formed according to a doctor blade method, and cut into 100 mm square pieces. The first dielectric green sheet and the second dielectric green sheet were prepared.

The magnetic green sheet was prepared by the following procedure. Fe ₂ O ₃ , NiO, ZnO and CuO were mixed at a mixing ratio of 100, 20, 30 and 10 parts by weight, respectively, and the mixture was calcined at a temperature of 780 ° C. and crushed to obtain the first magnetic material. The body was calcined powder. The same mixture was calcined at a temperature of 760 ° C. and crushed to obtain a second magnetic calcined powder. An organic binder is added to each of the two kinds of calcined powders of the magnetic material and kneaded to form a slurry, and a magnetic material green sheet having a thickness of 60 μm is formed according to a doctor blade method, and the magnetic green sheet is cut into 100 mm square pieces. The 1st magnetic substance green sheet and the 2nd magnetic substance green sheet were prepared, respectively. The first
A green sheet was prepared on which a plurality of capacitor internal electrode patterns for obtaining electrostatic capacitance were printed using the dielectric green sheet and the Ag paste.

A green sheet was prepared in which a plurality of coil conductor patterns for obtaining the inductance were printed using the first magnetic green sheet and Ag paste.

When these are prepared, a plurality of first dielectric green sheets on which the capacitor internal electrodes are not printed are stacked to form a cover sheet, and then the first dielectric on which the capacitor internal electrode patterns are printed. A predetermined number of green sheets are stacked to form a capacitor section, a second dielectric green sheet is stacked next, a second magnetic green sheet is stacked next, and then a first magnetic layer on which a coil conductor pattern is printed. A predetermined number of green body green sheets were stacked to form an inductor portion, and a predetermined number of first magnetic green sheets on which coil conductor patterns were not printed were stacked to form a cover sheet. The laminate thus produced was pressure-bonded, divided into individual laminated filters, subjected to binder removal treatment, and then fired at a temperature of 900 ° C.

Twenty pieces are randomly taken out from the fired laminated body, and the peripheral surface where the joint 5 between the dielectric and magnetic material of the fired laminated body is exposed is searched so as to cross the joint 5. As a result of measurement with a needle type surface roughness meter, the maximum height of the exposed portion of the joint 5 was 1.3 μm, and the peripheral surface was generally smooth.

These laminated bodies are coated with Ag paste on both end faces thereof and then baked to form input terminals and output terminals, and ground terminal electrodes 9 and non-contact terminal electrodes 10 are formed on opposite side surfaces. did. These laminated L
As a result of mounting the C filter on the circuit board by the automatic component mounting machine, the soldered mounting state was good.

[0016]

[Comparative Example] The same result as in Example except that the second dielectric green sheet 2 and the second magnetic green sheet 4 were not used in the example. As a result, bonding on the side surface of the laminated body after firing was performed. The maximum height of the exposed part of part 5 is 3
It was 0 μm, and when the side surface was placed on a flat plate, it was in an inclined state. In addition, as a result of mounting the laminated LC filter forming the terminal electrodes on the circuit board by the component automatic mounting machine,
The mounting position of the soldered laminated LC filter was inclined, and the soldering strength was weak in some cases.

[0017]

According to the present invention, the firing and shrinkage of the dielectric ceramic green sheet forming the capacitor portion and the magnetic ceramic green sheet forming the inductor portion are made substantially equal to each other, and the shrinkage is smaller than that of the dielectric ceramic green sheet. The second dielectric porcelain green sheet 2 having a large rate and the second magnetic porcelain green sheet 4 having a contraction rate larger than that of the magnetic porcelain green sheet are arranged at the joint portion 5 of the dielectric and the magnetic body and laminated to form different types. By utilizing the fact that the sinterability is reduced and the shrinkage rate is reduced in the joint portion 5 of the material, the contraction after firing of the laminated body is made to be the same as the contraction of the portion other than the joint portion 5. The peripheral surface where 5 was exposed became smooth. Since the terminal electrode is formed on the smooth surface, the mounting on the circuit board or the like becomes good. Therefore, according to the present invention, the soldering is well performed, and the effect of improving the reliability of the laminated LC filter is obtained.

[Brief description of drawings]

FIG. 1 is a schematic enlarged view of a joint portion of a laminated LC filter of the present invention.

FIG. 2 is a schematic enlarged view of a joint portion of a conventional laminated LC filter.

FIG. 3 is a diagram schematically showing a configuration of a laminated LC filter of the present invention.

[Explanation of symbols]

 1 1st Dielectric Porcelain 2 2nd Dielectric Porcelain 3 1st Magnetic Body Porcelain 4 2nd Magnetic Body Porcelain 5 Junction 6 Joint Ridge 7 Input Terminal Electrode 8 Output Terminal Electrode 9 Ground Terminal Electrode 10 Non-contact terminal electrode

Claims (2)

[Claims] 1. A laminated LC filter in which a dielectric porcelain and a magnetic porcelain are laminated to be integrally formed, and a first dielectric porcelain and a main part of the magnetic porcelain constituting a main part of the dielectric porcelain. And a first dielectric porcelain that composes the first dielectric porcelain and a second dielectric porcelain having a contraction rate different from that of the main part, respectively, and a thin layer of the second magnetic porcelain. A laminated LC filter characterized in that a peripheral surface which intersects with a bonding surface with a magnetic porcelain is a smooth surface which does not include a ridge. 2. (a) A step of forming a first dielectric green sheet by mixing and calcining a dielectric ceramic raw material powder;
(B) A step of forming a capacitor section green sheet in which an electrode for obtaining an electrostatic capacity is printed on the dielectric green sheet; (c) a first magnetic green material obtained by mixing and calcining a magnetic ceramic raw material powder. A step of forming a sheet; (d) a step of forming a green sheet for an inductor part in which a coil conductor is printed on the magnetic green sheet; (e) a pressure bonding and firing of the green sheet to separate the capacitor part and the inductor part. A method of manufacturing a laminated LC filter, comprising the steps of: integrally forming; and (f) a step of forming a terminal electrode on the end face of the laminated body, including the following steps. (A) A second dielectric green sheet (2) calcined at a temperature lower than the calcining temperature of the raw material powder constituting the first capacitor section green sheet. Forming step, (b) forming a second magnetic green sheet (4) calcined at a temperature lower than the calcining temperature of the raw material powder forming the first inductor green sheet, and (c) A second dielectric green sheet (2) is stacked next to the first group of green sheets for capacitor section, and then a second magnetic green sheet (4) is stacked.
Further, a step of stacking and stacking the stacked group of the first green sheets for the inductor portion.