JP2907365B2 - Multilayer LC filter and method of manufacturing the same - Google Patents

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 is provided in a dielectric ceramic, an inductor is provided in a magnetic ceramic, and a dielectric ceramic and a magnetic ceramic are integrally formed. The capacitor and the inductor are electrically connected to form a lumped-constant LC filter, for example. In the case of a lumped-constant type LC filter, an input terminal electrode 7 and an output terminal electrode 8 are connected to the opposite end face of the laminate and a peripheral surface connected to the end face, and the ground terminal electrode 9 is in non-contact with the opposite side face of the laminate. A terminal electrode 10 is configured.

[0003] 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, the raw material powder of the magnetic material is mixed, calcined, and kneaded with an organic binder to form 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 portion, and a plurality of the magnetic green sheets are stacked thereon and laminated and pressed as an inductor portion, followed by firing. By firing, the capacitor portion and the inductor portion are connected to each other and provided inside the laminate. 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 end surfaces and side surfaces of the laminate.

To mount the laminated LC filter on a circuit board, a suction nozzle of an automatic component mounting machine is used. That is, the laminated LC filter is decompressed and adsorbed 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 three lands formed on the circuit board. Mounted and soldered.

[0005]

The laminated body in which a capacitor and an inductor are internally provided integrally forms a dielectric porcelain and a magnetic porcelain.

[0006] Although various measures have been taken to approximate the contraction rate of the dielectric green sheet and the contraction rate of the magnetic green sheet, the joint between the dielectric green sheet and the magnetic green sheet is made of raw materials having different compositions. Since the sintering is performed in the contact state, the sinterability of the joined portion is deteriorated and the shrinkage rate is reduced. As shown in FIG.
And the peripheral surface where the joint is exposed is no longer flat. Since the ground terminal electrode 9 and the non-contact terminal electrode 10 are formed after the joint portion 5 projects, the suction nozzle of the automatic component mounting machine attempts to convey the surface on which the non-contact terminal electrode 10 is formed under reduced pressure. Then, there is a problem that the vacuum suction becomes insufficient and a transport error may occur. Furthermore, when such a multilayer LC filter is mounted on a circuit board, one end of the mounting surface of the multilayer LC filter rises from the circuit board and is not mounted flat. There is also a problem that the laminated LC filter mounted in this manner lacks reliability in terms of soldering strength, vibration, and the like.

[0007] An object of the present invention is to improve the shrinkage rate of the joint portion 5 made of dissimilar materials, and to solve the above-mentioned problem.
It is to provide a C filter and a manufacturing method thereof.

[0008]

The gist of the means for solving the problem is, first, a laminated LC filter in which a dielectric ceramic and a magnetic ceramic are laminated and integrally formed, and FIG. 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 contraction rate different from that of the main part. A junction 5 between the dielectric ceramic and the magnetic ceramic, which is joined via thin layers of the dielectric ceramic and the second magnetic ceramic;
Is a laminated LC filter having a smooth exposed peripheral surface,
Secondly, there is provided a method of manufacturing the laminated LC filter, wherein a step of mixing and calcining a dielectric ceramic raw material powder to form a first dielectric green sheet 1; Forming a green sheet for a capacitor portion on which an electrode for acquisition is printed, mixing and calcining a raw material powder of a magnetic ceramic to form a first magnetic green sheet 3; A step of forming a green sheet for an inductor section on which a coil conductor is printed; a step of pressing and firing the green sheet to integrally form the capacitor section and the inductor section; and forming a terminal electrode on an end face of the laminate. And a step of calcining at a temperature lower than the calcining temperature of the raw material powder constituting the first capacitor portion green sheet. Forming the second dielectric green sheet 2 and forming the second magnetic green sheet 4 calcined at a temperature lower than the calcining temperature of the raw material powder constituting the first inductor part green sheet. When,
Next to the stacking of the first capacitor unit green sheets, a second dielectric green sheet 2 calcined at a low temperature is overlapped, and then a second magnetic green sheet 4 calcined at a low temperature is stacked, And a step of laminating and laminating the laminate of the first inductor part green sheets.

[0009]

When firing the laminate, a green sheet having a higher shrinkage ratio than each of the green sheets is arranged and laminated at a portion where the dielectric green sheet and the magnetic green sheet are in contact with each other, and fired. Although the sinterability is reduced in the portion where different materials come into contact with each other, the contraction rate of the joint 5 is reduced, but the green sheet having a large shrinkage is
, The contraction rate of the joint 5 can be made substantially equal to the contraction rate of the inductor section and the capacitor section. As a result, an effect of preventing the occurrence of the ridge in the joining portion 5 of the dissimilar material is obtained.

[0010]

EXAMPLE A dielectric green sheet was prepared according to the following procedure. TiO ₂ , NiO and CuO are 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.
Was calcined powder of dielectric. 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 dielectric calcined powders, and the mixture is kneaded to form a slurry. A dielectric green sheet having a thickness of 70 μm is formed according to a doctor blade method. The first dielectric green sheet and the second dielectric green sheet were each prepared.

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

A green sheet is prepared by printing a plurality of coil conductor patterns for obtaining inductance using the first magnetic green sheet and the Ag paste.

When these are ready, a plurality of first dielectric green sheets on which the capacitor internal electrodes are not printed are laminated to form a cover sheet, and then the first dielectric green sheet on which the capacitor internal electrode patterns are printed is formed. A predetermined number of green sheets are stacked to form a capacitor portion, then a second dielectric green sheet is stacked, then a second magnetic green sheet is stacked, and then a first magnetic sheet on which a coil conductor pattern is printed is printed. A predetermined number of body green sheets were stacked to form an inductor portion, and a predetermined number of first magnetic green sheets on which no coil conductor pattern was printed were stacked to form a cover sheet. The laminate thus obtained was pressure-bonded, cut into individual laminated filters, subjected to binder removal treatment, and then fired at a temperature of 900 ° C.

Twenty pieces are taken out at random from the fired laminate, and are traversed across the joint 5 on the exposed surface of the joint 5 between the dielectric and the magnetic material of the fired laminate. As a result of measurement with a needle type surface roughness tester, the maximum value of the height of the exposed portion of the joint portion 5 was 1.3 μm, and the peripheral surface was generally smooth.

An Ag paste is applied to both end surfaces of these laminates, followed by baking to form input terminals and output terminals, and form a ground terminal electrode 9 and a non-contact terminal electrode 10 on opposing side surfaces. did. These laminates L
As a result of mounting the C filter on the circuit board by the automatic component mounting machine, the mounted state by soldering was good.

[0016]

COMPARATIVE EXAMPLE In the example, except that the second dielectric green sheet 2 and the second magnetic green sheet 4 were not used, the same result as in the example was obtained. The maximum height of the exposed part of the part 5 is 3
0 μm, and the side face was inclined when placed on a flat plate. In addition, as a result of mounting the laminated LC filter having the terminal electrodes on the circuit board by using an automatic component mounting machine,
The mounting position of the soldered laminated LC filter was inclined, and some of the soldering strength was low.

[0017]

According to the present invention, the firing shrinkage of the dielectric porcelain green sheet constituting the capacitor portion and the firing porosity of the magnetic porcelain green sheet constituting the inductor portion are substantially matched, and the shrinkage from the dielectric porcelain green sheet is reduced. The second dielectric porcelain green sheet 2 having a higher modulus and the second magnetic porcelain green sheet 4 having a higher contraction rate than the magnetic porcelain green sheet are arranged at the joint 5 between the dielectric and the magnetic material and laminated. By utilizing the fact that the sinterability is reduced and the shrinkage rate is reduced at the joint portion 5 of the material, the shrinkage of the laminate after firing is the same as that of the portion other than the joint portion 5, so that the joint portion is reduced. The exposed surface of No. 5 became smooth. Since the terminal electrodes are formed on a smooth surface, the mounting on a circuit board or the like is improved. Therefore, according to the present invention, the soldering was performed well, and the effect of improving the reliability of the laminated LC filter was obtained.

[Brief description of the drawings]

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

FIG. 2 is a schematic enlarged view of a junction 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]

 DESCRIPTION OF SYMBOLS 1 1st dielectric porcelain 2 2nd dielectric porcelain 3 1st magnetic porcelain 4 2nd magnetic porcelain 5 Joining part 6 Joint ridge 7 Input terminal electrode 8 Output terminal electrode 9 Ground terminal electrode 10 Non-contact terminal electrode

Claims (2)

(57) [Claims] 1. A dielectric magnet constituting a main part of a capacitor.
Layer and the magnetic ceramic layer that constitutes the main part of the inductor
A laminated LC filter integrally formed by bonding.
Therefore, at least the first dielectric ceramic layer constituting the capacitor differs from the first dielectric ceramic layer.
When laminating a thin layer of the second dielectric porcelain with firing shrinkage
Together, the first magnetic porcelain layer constituting the inductor
Laminate thin layers of second magnetic porcelain with different firing shrinkage
And the dielectric ceramic layer and the magnetic material
A laminated LC filter characterized by joining with a porcelain layer
Ruta. 2. Mixing and calcining raw materials of dielectric ceramics
Forming a first dielectric green sheet;
An electrode is formed on the conductor green sheet, and the capacitor
A step of forming a lean sheet;
Mixing and calcining to form the first magnetic green sheet
And forming a coil conductor on this magnetic green sheet.
Forming a green sheet for the inductor part
These green sheets are laminated, pressed and fired, and
Forming the capacitor and inductor together
And in the method of manufacturing a laminated LC filter including
And a dielectric porcelain constituting the first dielectric green sheet.
The second calcined at a temperature lower than the calcining temperature of the raw material powder
Forming a dielectric green sheet (2),
Magnetic porcelain raw material constituting the first magnetic green sheet
A second magnet calcined at a temperature lower than the calcining temperature of the powder
Forming a green body sheet (4);
The second dielectric is added to the green sheet laminate for the denser part.
Stacking the body green sheet (2), and further adding the second magnetic
After stacking the body green sheet (4),
Manufacturing a laminated LC filter, comprising: laminating and pressing a stack of green sheets for use.
Method.