JPH06120065A - Manufacture of multilayer ceramic inductor - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a multilayer ceramic inductor, wherein the ceramic inductor is prevented from deviating in multilayer even if an inner conductor pattern is small in line width. CONSTITUTION:An inner electrode conductive paste 2 is printed as thick as 25mum on the surface of a ceramic green sheet 1 of 30mum thickness through a printing screen plate which is provided with an opening of the same shape with an inner conductor pattern (120mum in line width) and where a masking part 10mum in width and dividing the pattern in half in the lengthwise direction of a pattern line is provided. When a printing pressure is removed after printing, the two inner electrode conductive pastes 2 each rectangular in section and printed in parallel sandwiching a slit 3 between them are deformed at once into a hemispherical form whose top is recessed due to leveling, and then the slit 3 disappears completely. Then, two or more of the ceramic green sheets 1 are stacked in a certain constitution and pressure-joined, the obtained multilayer body is cut into pieces of chip size, which are burned, and then an outer electrode is provided to the end face of a chip where a coil end is led outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a monolithic ceramic inductor, and more particularly to a method for manufacturing a monolithic ceramic inductor in which the occurrence of stacking misalignment during the pressure bonding of a stack is significantly suppressed.

[0002]

2. Description of the Related Art Conventionally, a laminated ceramic inductor has been generally manufactured by the following method. First, using a printing screen plate in which a plurality of ceramic green sheets with through holes are laminated and through holes are connected to form a spiral coil, an internal conductor pattern-shaped opening is formed. Screen-print the conductive paste for electrodes. Next, these sheets are laminated in a predetermined structure and pressure-bonded. Next, the obtained laminated body is cut into a chip size and fired, and then an external electrode is formed on the end face from which the coil end is led out.

In general, the cross-section in the line width direction of the conductive paste for internal electrodes printed on the above-mentioned sheet has a slightly widened hem width due to its wettability, the side surface rises with a smooth curved surface due to surface tension, and the upper surface becomes flat. (This is called leveling).

[0004]

In the monolithic ceramic inductor manufactured as described above, the line width of the internal conductor pattern becomes narrower with the progress of miniaturization in recent years, and the thickness of the ceramic green sheet becomes smaller. The thickness is reduced to almost the same thickness as the internal conductor pattern.

However, when the line width of the internal conductor pattern is reduced, the conductive paste for internal electrodes printed on the sheet does not have a flat upper surface due to the leveling, and the cross section in the line width direction has a high central portion. It becomes a semi-circular shape that rises. Therefore, when ceramic green sheets with such an internal conductive paste having a semi-circular cross section are stacked and pressure-bonded, pressure is concentrated at the apex of the conductive paste for internal electrodes with a semi-circular cross section, causing a stacking deviation. However, there is a problem that is likely to occur.

Therefore, the present invention solves the above-mentioned problems of the prior art, and provides a method of manufacturing a laminated ceramic inductor capable of preventing the occurrence of stacking deviation even when the line width of the internal conductor pattern is small. The purpose is to provide.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, have slits of a constant width that divide the internal conductor pattern into two in a direction orthogonal to the line width direction. It has been found that the above problems can be solved by printing a conductive paste for internal electrodes by using a printing screen plate having an opening such that the above-mentioned problem is formed, and has reached the present invention.

That is, according to the present invention, a printing screen having an opening in the shape of an internal conductor pattern, in which a spiral coil is formed by stacking a plurality of ceramic green sheets having through holes and connecting the ceramic green sheets by through holes. Print the conductive paste for internal electrodes using the plate,
A method for manufacturing a laminated ceramic inductor, comprising laminating and pressing these sheets, followed by firing to form an external electrode on an end face where a coil end is led out, wherein the conductive paste for internal electrode is formed into an opening having an internal conductor pattern shape. A method of manufacturing a multilayer ceramic inductor, comprising: printing using a printing screen plate having a masking portion having a constant width that divides the pattern into two in a direction orthogonal to the line width direction of the pattern. It is provided.

[0009]

According to the method of the present invention, the conductive paste for internal electrodes is provided with a masking portion having an opening in the shape of an internal conductor pattern and dividing the pattern into two in a direction orthogonal to the line width direction of the pattern. It is printed using the printing screen plate prepared. In the conductive paste for internal electrodes printed using such a screen plate, slits, that is, paste unapplied grooves are formed along the center line of the internal conductor pattern, and the slits are divided into two.

As described above, the two conductive pastes for the internal electrodes arranged in parallel with the slit interposed therebetween are screen-printed and
As soon as the printing pressure is removed, the line width is widened by leveling, and the slits are filled to integrate them. That is, the width of the slit in the method of the present invention must be such that it is filled by the leveling of the conductive paste that occurs after printing.

As described above, the conductive paste for the internal electrodes, which is divided into two and printed by the presence of the slits, is integrated by the leveling, but the conductive paste is not sufficiently supplied to the portion having the slits. It will be slightly depressed. Therefore, the cross-section in the line width direction of the internal conductor pattern formed on the sheet has a shape having two bulges in which the central portion of the semicircle is recessed, that is, a shape in which B is laid sideways. is there.

When the sheets on which the internal conductor patterns having such a cross section are formed are laminated, the lower main surface of the sheets is
It contacts the vertices of the two raised portions on the surface of the lower inner conductor pattern. Therefore, the pressure when the laminated body is pressure-bonded is not concentrated on the apex of one raised portion unlike the conventional internal conductor pattern having a semicircular cross section, and is distributed to the apex of two raised portions, The occurrence of stacking displacement is significantly reduced.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by the following examples.

[0014]

Example 1 First, a spiral shape was formed by stacking as shown in FIG. 1A on the surface of a ceramic green sheet 1 having a thickness of 30 μm in which through holes (not shown) were formed and connecting through holes. The line width that the coils of are constructed 1
An internal electrode with a thickness of 25 μm using a printing screen plate having an opening of 20 μm in the shape of an internal conductor pattern and provided with a masking portion with a width of 10 μm that divides the pattern into two in a direction orthogonal to the line width direction of the pattern. The conductive paste 2 was printed (FIG. 1).

When the printing pressure is removed after printing, the two conductive electrodes for internal electrodes arranged in parallel with the slit 3 having a cross section in the direction orthogonal to the line width direction having the shape shown in FIG. The paste 2 was immediately integrated by leveling, and the cross section in the direction orthogonal to the line width direction had a shape as shown in FIG. 2B (FIG. 2).

Next, a plurality of the above-mentioned sheets 1 having a predetermined structure were laminated and pressure-bonded. Next, the obtained laminated body was cut into a chip size, and after firing this, an external electrode was formed on the end face from which the coil end was extended to obtain a laminated ceramic inductor.

In the laminated ceramic inductor manufactured as described above, the occurrence of laminated displacement was extremely small, and the effect of the method of the present invention was confirmed.

[0018]

Comparative Example 1 The surface of the ceramic green sheet 1 having a thickness of 30 μm and having through holes (not shown) is formed on the surface of FIG.
A spiral coil is formed by stacking and connecting through holes as shown in Fig. 1 and using a printing screen plate (with no masking part) having an opening with an internal conductor pattern shape with a line width of 120 μm. A multilayer ceramic inductor was manufactured in the same manner as in Example 1 except that the conductive paste 2 for internal electrodes having a thickness of 25 μm was printed.

As a result, the obtained monolithic ceramic inductor generated far more lamination deviation than that of Example 1.

[0020]

As a result of the development of the method of the present invention, the occurrence of stacking misalignment during pressure bonding of a stack has been significantly suppressed. Therefore, the productivity is improved and the reliability of the laminated ceramic inductor is improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing a state immediately after printing an example of an internal conductor pattern (before leveling) on a ceramic sheet with a conductive paste for internal electrodes by the method of the present invention, in which (a) is a top view, FIG. 9B is a cross-sectional view of the case where the dashed-dotted line portion in FIG.

2A and 2B are views showing a state after leveling of the conductive paste for internal electrodes printed on the ceramic sheet in FIG. 1, in which FIG. 2A is a top view and FIG. FIG.

FIG. 3 is a diagram showing a mode after an example of an internal conductor pattern is printed (after leveling) on a ceramic sheet by a conductive paste for internal electrodes by a conventional method,
(A) is a top view, (b) is a cross-sectional view of the one-dot chain line part in (a).

[Explanation of symbols]

 1 ... Ceramic green sheet 2 ... Conductive paste for internal electrodes 3 ... Slit

Claims (1)

[Claims] 1. A printing screen plate having an opening in the shape of an internal conductor pattern in which a spiral coil is formed by stacking a plurality of through-hole-connected ceramic green sheets and connecting the through holes to each other. A method for manufacturing a laminated ceramic inductor, comprising printing an internal electrode conductive paste, laminating and pressing these sheets, and then firing the sheets to form an external electrode on an end face from which a coil end is led out. Printing the paste using a printing screen plate having an opening in the shape of an internal conductor pattern and provided with a masking portion for dividing the pattern into two in a direction orthogonal to the line width direction of the pattern. Manufacturing method of ceramic inductor.