JP3428882B2 - Manufacturing method of multilayer inductor - Google Patents

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 laminated inductor.

[0002]

2. Description of the Related Art Conventionally, in a general method for manufacturing a laminated inductor, a conductor pattern serving as an internal conductor is formed on the surface of a magnetic sheet serving as an insulating layer, and a magnetic sheet having this conductor pattern is formed. A method is adopted in which, after laminating and applying a predetermined pressure to electrically connect the upper and lower conductor patterns to each other through the through-holes, the conductor patterns are fired in a predetermined atmosphere to further form external electrodes that conduct to the internal conductors. ing.

In this method of manufacturing a laminated inductor, residual stress is generated due to the difference in linear expansion coefficient between the insulating layer and the internal conductor during the cooling process after firing, causing internal strain, which results in stress magnetostriction during use. Occurs, and the magnetic characteristics (L,
However, there is a problem that Q) is deteriorated.

As a solution to this problem, there is known a method of relaxing the stress strain between the insulating layer and the internal conductor by providing a void in all or part of the insulating layer and the internal conductor. .

However, when a space is provided between the insulator layer and the internal conductor in this way, water, a plating solution,
There was a risk that liquids such as flux would enter and the L and Q values would decrease.

On the other hand, as a method for preventing the penetration of a liquid such as a plating solution and alleviating the stress strain, there is known a method of performing thermal shock treatment or high temperature treatment in the manufacturing process of the laminated inductor.

As a manufacturing method for applying thermal shock treatment, for example, Japanese Patent Laid-Open No. 8-148363 discloses a temperature difference of 120.
A method is disclosed in which the thermal shock treatment at a temperature of 0 ° C. or higher is performed once or more.

Further, as a manufacturing method in which high temperature treatment is performed, for example, in Japanese Unexamined Patent Publication No. 4-350913, 600-9
A method of performing high temperature treatment at 00 ° C. for 1 hour is disclosed.

[0009]

However, in the above-described conventional thermal shock treatment and high temperature treatment, there is a problem that cracks occur due to rapid heating and rapid cooling, and the strength is lowered.

In view of the above-mentioned problems, an object of the present invention is to provide a laminated inductor capable of reducing the occurrence of cracks and the reduction of strength and causing no stress strain without providing a gap between the insulating layer and the internal conductor. It is to provide a manufacturing method.

[0011]

In order to achieve the above-mentioned object, the present invention is characterized in that, in claim 1, a laminate formed by laminating insulator layers having conductor patterns serving as internal conductors on the surface is fired. In a method of manufacturing a laminated inductor in which a sintered body is formed and the laminated body is a laminated inductor, a step of subjecting the sintered body to a heat treatment is provided, and at the time of temperature increase and temperature decrease in the heat treatment. We propose a method for manufacturing a laminated inductor in which the temperature lowering rate at least during cooling is set to 20 ° C./minute or less.

According to the method of manufacturing the laminated inductor, the sintered body is heat-treated to form a space between the inner conductor and the insulator layer without providing a gap between the insulator layer and the inner conductor. Is subjected to a large stress, the metal constituting the inner conductor is stretched, and the metal atoms or metal molecules are rearranged. Thereby, the stress strain generated between the internal conductor and the insulating layer in the cooling process after firing is relaxed. Furthermore, since the temperature lowering rate at least during the temperature lowering during the heat treatment and the temperature lowering during the heat treatment is set to 20 ° C./minute or less, the sintered body is not rapidly cooled, so that the occurrence of cracks is prevented.

According to a second aspect of the present invention, in the method of manufacturing a laminated inductor according to the first aspect, as the heat treatment, the sintered body is subjected to a thermal shock treatment of a temperature difference of 120 ° C. or more once or more, and A method for manufacturing a laminated inductor is proposed in which the temperature rising rate and the temperature lowering rate in the thermal shock treatment are set to 20 ° C./minute or less.

According to the method of manufacturing the laminated inductor, the thermal shock treatment is performed once or more on the sintered body so that the temperature difference is 120 ° C. or more, even if no void is provided between the insulator layer and the internal conductor. As a result, a large stress is applied between the inner conductor and the insulator layer, the metal forming the inner conductor is stretched, and the metal atoms or metal molecules are rearranged. Thereby, the stress strain generated between the internal conductor and the insulating layer in the cooling process after firing is relaxed. Further, since the rate of temperature rise during temperature rise and the rate of temperature decrease during temperature fall in the thermal shock treatment are set to 20 ° C./min or less, the sintered body is not rapidly heated or rapidly cooled, so cracks are prevented from occurring. .

According to a third aspect of the present invention, in the method of manufacturing a laminated inductor according to the first aspect, the heat treatment is a high temperature treatment for one hour or more at a predetermined temperature between 400 ° C. and 950 ° C. for the sintered body. And a method for manufacturing a laminated inductor in which the temperature lowering rate at the end of the high temperature treatment is set to 20 ° C./minute or less.

According to the method for manufacturing the laminated inductor, the sintered body is kept at a predetermined temperature of 400 ° C. to 950 ° C. for 1 hour or more without forming a gap between the insulator layer and the internal conductor. By performing the high temperature treatment, a large stress is applied between the inner conductor and the insulator layer, the metal forming the inner conductor is elongated, and the metal atoms or metal molecules are rearranged. Thereby, the stress strain generated between the internal conductor and the insulating layer in the cooling process after firing is relaxed. Further, the temperature decreasing rate at the time of temperature decrease in the high temperature treatment is 20 ° C.
Since the sintered body is set to be less than 1 minute, the sintered body is not rapidly cooled, so that the generation of cracks is prevented.

[0017]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of a laminated inductor according to the present invention, and FIG. 2 is an exploded perspective view of a main part thereof. As shown in FIG. 1, the laminated inductor according to the present embodiment has
The main body 1 has a rectangular parallelepiped shape of, for example, 1.6 × 0.8 × 0.8 mm, and has external electrodes 2 and 3 conductively connected to the internal conductors at both ends in the longitudinal direction.

As shown in FIG. 2, the main body 1 has a plurality of magnetic material sheets 22-1 to 22 in which conductor patterns 21-1 to 21-n (n is a natural number) serving as internal conductors are formed. -n and the magnetic material sheet 23 on which the conductor pattern is not formed are laminated and integrally formed.

Conductor patterns of the magnetic sheets 22-1 to 22-n
21-1 to 21-n are formed of, for example, a conductor containing silver (Ag) as a main component, and each of the conductor patterns 21-1 to 21-n.
-n are conductively connected to each other through the through-hole 24 so as to have a spiral shape, thereby forming a coil. Furthermore, the conductor pattern of the portion corresponding to both ends of this coil
That is, one end of the conductor pattern 21-1 and the conductor pattern 2
The other end of 1-n is formed so as to be exposed at the end face of the main body 1 in the longitudinal direction.

A conductor pattern 21 exposed at one end of the main body 1.
-1 is the external electrode 2 and the conductor pattern 2 exposed at the other end
1-n are conductively connected to the external electrodes 3, respectively.

In the present embodiment, the conductor pattern 2
The number of turns of the coil formed by 1-1 to 21-n is 1
It was set to 6.

Next, a first embodiment of the method for manufacturing a laminated inductor according to this embodiment will be described. Ni-Zn-
The Cu ferrite slurry was applied by the green sheet method.
It is formed on a magnetic sheet having a thickness of about 30 μm.

A through hole is formed in this magnetic sheet, and the magnetic sheet having the through hole and the magnetic sheet not having the through hole have, for example, A
Conductive pattern is formed by screen-printing conductive paste such as g.

Magnetic sheets on which conductor patterns are printed are laminated so as to be electrically connected. At this time, a dummy sheet having no conductor pattern formed on the upper and lower layers is arranged according to the desired dimension.

After pressing this laminated body under a constant pressure, it is cut into a desired shape. Here, since the laminated body is pressure-bonded to each other, the upper and lower magnetic material sheets and the magnetic material sheet and the conductor pattern are in close contact with each other, and no void is generated between them. .

Next, the cut laminated body is subjected to binder removal treatment in air at 350 to 550 ° C., and further fired in air at 850 to 950 ° C. to obtain a sintered body.

On both end faces of the obtained sintered body, which face each other, a conductor paste such as Ag is applied by dipping or the like and baked to form an external electrode, and the external electrode is plated with Ni and Sn to form a laminated inductor. Make up.

The magnetic sheet is not limited to Ni-Zn-Cu ferrite, but may be spinel type ferrite such as Ni-Zn ferrite, Ni-Cu ferrite, Mn-Cu ferrite.

The method of forming the magnetic material sheet is not limited to the green sheet method, and may be a printing method or the like.

The material of the inner conductor and the outer electrode is not limited to Ag, but may be Ag-Pd, Ni, Cu or alloys thereof.

The method of forming the internal conductor pattern is not limited to screen printing, and transfer, vapor deposition, sputtering, etc. may be used.

The method of forming the external electrodes is not limited to the application of dip or the like, and transfer, printing, vapor deposition, sputtering or the like may be used.

The timing of forming the external electrodes is not limited to after firing, but may be before firing.

The plating is not limited to wet type, but may be dry type such as vapor deposition and sputtering.

Next, the fired laminated inductor is subjected to a thermal shock treatment under the conditions of a temperature difference of 120 ° C. or more and a temperature rising / falling rate of 20 ° C./min or less.

By carrying out this thermal shock treatment, the conductor patterns 21-1 to 21-n and the magnetic material sheets 22-1 to 22-n are obtained.
A large stress is applied between the conductor pattern 2 and
Extend the metal such as Ag that composes 1-1 to 21-n to
Rearranges metal atoms or metal molecules, etc., and in the cooling process after firing, the conductor patterns 21-1 to 21-n and the magnetic material sheet
22-1 to 22-n to alleviate the stress strain generated between them.

FIG. 3 shows the results of an experiment in which changes in the L value, Q value, humidity resistance load test characteristics, and bending strength of the laminated inductor were investigated by changing the temperature difference and the number of times of heat shock treatment using a heat cycle device. FIG.

Examples 1 to 6 were carried out as examples of the thermal shock treatment in the first embodiment, and comparative examples 1 to 5 were carried out as comparative examples.

In this experiment, for the measurement of L value and Q value, YHP4195A was used as a measuring instrument and YHP16092A was used as a measuring jig, and the measuring current was set to 1 mA. The reliability (moisture resistance load test: measurement of change rate of L value and Q value at 1000 hours) is 40 ° C, 95RH, 15
mA, and a tensile compression tester (SV50 20V: Imada Seisakusho) was used as a measuring instrument to measure the bending strength (three-point bending test), and the L interval was 0.6 mm and the tip was R0.5 mm.
Set to.

Further, Comparative Examples 3, 4, 5 and Example 1,
Comparative Examples 2 and 3, 4 and 5 were carried out by using cooled carbon dioxide gas as the low temperature side refrigerant in the heat cycle device.
And Example 6 was performed using liquid nitrogen, cooled nitrogen gas, or the like as the low temperature side refrigerant in the heat cycle device.

When liquid nitrogen is used, a heat insulating material such as resin, plastic or expanded polystyrene is wrapped around the inner wall of the sample bottle, the laminated inductor after firing is put in this sample bottle, and this sample bottle is placed in the medium on the low temperature side. Alternatively, it is added to the medium on the high temperature side. The atmosphere is filled with a material such as vacuum or He which is not liquefied at -180 ° C. In this state, the immersion of the low temperature side medium into the liquid nitrogen and the high temperature side medium (for example, water) is repeated according to the number of treatments.

The conditions of the thermal shock treatment in each example are as follows. That is, the conditions in Example 1 were that the low temperature side temperature was −55 ° C., the high temperature side temperature was 65 ° C., and the temperature difference was 120 ° C.
Temperature rising / falling rate is 20 ° C / min, number of cycles (number of treatments)
Is once.

The conditions in Example 2 were as follows: the low temperature side temperature was −55 ° C., the high temperature side temperature was 65 ° C., and the temperature difference was 120.
C., the rate of temperature increase / decrease is 20.degree. C./min, the number of cycles (the number of treatments) is 10, and the conditions in Example 3 are as follows: low temperature side temperature is −55 ° C., high temperature side temperature is 65 ° C., and temperature difference is 120.
C., the temperature rising / cooling rate is 20.degree. C./min, the number of cycles (the number of treatments) is 100, and the conditions in Example 4 are as follows: the low temperature side temperature is −55 ° C., the high temperature side temperature is 65 ° C., and the temperature difference is 120.
C., the rate of temperature increase / decrease was 10.degree. C./min, and the number of cycles (the number of treatments) was once.

Further, the conditions in Example 5 were as follows: the temperature on the low temperature side was −55 ° C., the temperature on the high temperature side was 125 ° C., and the temperature difference was 18.
0 ° C., the rate of temperature rise / fall is 20 ° C./min, the number of cycles (the number of treatments) is 1, and the conditions in Example 6 are as follows: the low temperature side is −180 ° C., the high temperature side is 20 ° C., and the temperature difference is 200
C., the rate of temperature increase / decrease was 20.degree. C./min, and the number of cycles (the number of treatments) was once.

On the other hand, Comparative Example 1 was an untreated product similar to the conventional one, which was not subjected to thermal shock treatment, and the conditions in Comparative Example 2 were as follows: the low temperature side temperature was -180 ° C, the high temperature side temperature was 20 ° C, and the temperature difference was 2.
The temperature in the comparative example 3 was -55 ° C, the temperature in the high temperature side was 125 ° C, and the temperature difference was 18
0 ° C., the temperature rising / falling rate is 40 ° C./min, the number of cycles (the number of treatments) is 1, and the conditions in Comparative Example 4 are as follows: the low temperature side temperature is −55 ° C., the high temperature side temperature is 45 ° C., and the temperature difference is 100
C., the rate of temperature increase / decrease is 20.degree. C./min, the number of cycles (the number of treatments) is 1, and the conditions in Comparative Example 5 are as follows: low temperature side temperature is -55.degree. C., high temperature side temperature is 45.degree. ℃,
Temperature rising / falling rate is 20 ° C / min, number of cycles (number of treatments)
Was 100 times.

Comparative Examples 1 to 5 are out of the scope of the present invention and are merely Comparative Examples.

As a result of this experiment, in Example 1, the L value was 4.6 μH (variation 4%) and the Q value was 38 (variation 1).
0%), the change rate of L value in the moisture resistance load test is + 7%,
The rate of change in Q value was + 7%, and the bending strength was 20 kgf / mm ² . Here, the variation of the L value and the Q value is “3σ / AV
The value is based on “E × 100”.

In the second embodiment, the L value is 4.5 μH.
(Variation: 4%), Q value: 40 (variation: 10%), L value change rate in humidity resistance load test was + 5%, Q value change rate was + 7%, and bending strength was 21 kgf / mm ² .

In Example 3, the L value was 4.6 μH (variation 4%), the Q value was 42 (variation 10%), the rate of change of the L value in the moisture resistance load test was + 3%, and the rate of change of the Q value was +5.
%, And the bending strength was 21 kgf / mm ² .

In Example 4, the L value was 4.6 μH (variation 4%), the Q value was 39 (variation 10%), the rate of change of the L value in the moisture resistance load test was + 5%, and the rate of change of the Q value was +5.
%, And the bending strength was 19 kgf / mm ² .

In Example 5, the L value was 4.7 μH (variation 4%), the Q value was 41 (variation 10%), the rate of change of the L value in the moisture resistance load test was + 3%, and the rate of change of the Q value was +4.
%, And the bending strength was 21 kgf / mm ² .

In Example 6, the L value was 4.7 μH (variation 4%), the Q value was 42 (variation 10%), the rate of change in the L value in the moisture resistance load test was + 3%, and the rate of change in the Q value was +3.
%, And the bending strength was 20 kgf / mm ² .

On the other hand, in Comparative Example 1, the L value is 3.5 μH.
(Variation: 4%), Q value: 25 (Variation: 10%), L value change rate in humidity resistance load test was + 30%, Q value change rate was + 40%, and bending strength was 21 kgf / mm ² .

In Comparative Example 2, the L value is 4.5 μH.
(Variation 10%), Q value is 37 (variation 20%),
In the moisture resistance test, the change rate of L value was + 15%, the change rate of Q value was + 35%, and the bending strength was 12 kgf / mm ² .

In Comparative Example 3, the L value is 4.2 μH (variation 8%), the Q value is 35 (variation 17%), the rate of change of the L value in the moisture resistance load test is + 20%, and the rate of change of the Q value is +.
The bending strength was 40% and the bending strength was 14 kgf / mm ² .

In Comparative Example 4, the L value was 3.8 μH (variation 8%), the Q value was 30 (variation 16%), the rate of change of the L value in the moisture resistance load test was + 25%, and the rate of change of the Q value was +.
42% and the bending strength was 21 kgf / mm ² .

In Comparative Example 5, the L value was 4.0 μH (variation 7%), the Q value was 32 (variation 16%), the rate of change of the L value in the moisture resistance load test was + 22%, and the rate of change of the Q value was +.
42% and the bending strength was 20 kgf / mm ² .

As is clear from the above experimental results, the thermal shock treatment is relaxed by applying the thermal shock treatment under the conditions specified in the present invention, and as a result, the flexural strength is maintained, L value improved by 28% or more, Q value improved by 50% or more,
A laminated inductance having good characteristics such that variations in L value and Q value are 4% or less and 10% or less, and change rates of L value and Q value in a humidity resistance load test are ± 10% or less and ± 30% or less, respectively. I was able to.

On the other hand, as shown in the comparative example, it was not possible to obtain a laminated inductor having desired desired characteristics even if the thermal shock treatment was performed under the condition outside the range specified in the present invention. .

That is, regarding the temperature difference of the thermal shock treatment, as shown in Comparative Examples 4 and 5, when the temperature was less than 120 ° C., L
It was not possible to obtain desired characteristics in terms of value, Q value, variations in these values, and reliability (moisture resistance load test). Further, as for the temperature rising / cooling rate, as shown in Comparative Examples 2 and 3, when the temperature was higher than 20 ° C./min, the L value, the Q value, the variations thereof, and the reliability (moisture resistance load test). The desired strength could not be obtained, and the bending strength was also reduced.

The method of thermal shock treatment is not limited to the above-mentioned method, and any other method may be used as long as the temperature difference is 120 ° C. or less and the temperature raising rate and the temperature lowering rate are 20 ° C./minute or less. good.

Next, a second embodiment of the method for manufacturing a laminated inductor according to the present invention will be described.

In the second embodiment, the shape of the laminated inductor, the structure of the internal conductor, and the steps from the formation of the magnetic material sheet to the formation of the laminated body, the sintered body, and the external electrode are the same as those described above.
The description is omitted because it is the same as the embodiment.

Further, the difference between the first embodiment and the second embodiment is that instead of the thermal shock treatment in the first embodiment, in the second embodiment, high temperature treatment is performed after firing. Especially.

That is, for the laminated inductor after firing,
The high temperature treatment is performed at a predetermined temperature between 400 ° C. and 950 ° C. for 1 hour or more and at a temperature lowering rate of 20 ° C./minute or less.

By applying this high temperature treatment, a large stress is applied between the conductor patterns 21-1 to 21-n and the magnetic material sheets 22-1 to 22-n, whereby the conductor patterns are formed. 21
-1 to 21-n, such as Ag, is stretched to rearrange metal atoms or metal molecules such as Ag, and conductor patterns 21-1 to 21-n and magnetic material in the cooling process after firing. The stress strain generated between the sheets 22-1 to 22-n is relaxed.

FIG. 4 shows the temperature of high temperature treatment using a fixed furnace.
Change the cooling rate at the end of processing to change the L
It is a figure which shows the experimental result which investigated the change of the value, Q value, the humidity resistance load test characteristic, and bending strength.

Examples 1 to 6 were carried out as examples of the high temperature treatment in the second embodiment, and comparative examples 1 to 4 were carried out as comparative examples.

In this experiment, for the measurement of L value and Q value, YHP4195A was used as a measuring instrument and YHP16092A was used as a measuring jig, and the measuring current was set to 1 mA. The reliability (moisture resistance load test: measurement of change rate of L value and Q value at 1000 hours) is 40 ° C, 95RH, 15
mA, and a tensile compression tester (SV50 20V: Imada Seisakusho) was used as a measuring instrument to measure the bending strength (three-point bending test), and the L interval was 0.6 mm and the tip was R0.5 mm.
Set to.

The conditions of the high temperature treatment in each example are as follows. That is, the condition in Example 1 is that the treatment temperature is 4
The temperature is 00 ° C. and the temperature lowering rate is 20 ° C./min.

The conditions in Example 2 were a treatment temperature of 600 ° C. and a temperature lowering rate of 20 ° C./minute, and the conditions of Example 3 were a treatment temperature of 800 ° C. and a temperature lowering rate of 20 ° C./min.
And the processing temperature is 950.
C., the rate of temperature decrease is 20.degree. C./min, the conditions in Example 5 are a treatment temperature of 600.degree. C. and a rate of temperature decrease of 10.degree.
The conditions in Example 6 were a treatment temperature of 600 ° C. and a temperature lowering rate of 5 ° C./min.

On the other hand, Comparative Example 1 was an untreated product similar to the conventional one that was not subjected to high temperature treatment, the conditions in Comparative Example 2 were a treatment temperature of 300 ° C., a temperature decreasing rate of 20 ° C./min, and the conditions of Comparative Example 3 were the same. , The processing temperature is 1000 ° C, and the cooling rate is 20
C./min., The condition in Comparative Example 4 was that the treatment temperature was 60.
The temperature was set to 0 ° C. and the temperature lowering rate was 40 ° C./min.

Comparative Examples 1 to 4 are outside the scope of the present invention and are merely comparative examples with respect to the Examples.

As a result of this experiment, in Example 1, the L value was 4.5 μH (variation 4%) and the Q value was 40 (variation 1).
0%), the change rate of L value in the moisture resistance load test is + 7%,
The rate of change in Q value was + 10%, and the bending strength was 19 kgf / mm ² . Here, the variation of the L value and the Q value is “3σ / A
VE × 100 ”.

In the second embodiment, the L value is 4.5 μH.
(Variation: 4%), Q value: 38 (Variation: 10%), L value change rate in humidity resistance load test was + 7%, Q value change rate was + 12%, and bending strength was 21 kgf / mm ² .

In Example 3, the L value was 4.7 μH (variation 4%), the Q value was 37 (variation 10%), the rate of change of the L value in the humidity resistance load test was + 3%, and the rate of change of the Q value was +1.
The bending strength was 0% and the bending strength was 21 kgf / mm ² .

In Example 4, the L value was 4.9 μH (variation 4%), the Q value was 35 (variation 10%), the change rate of the L value in the moisture resistance load test was + 3%, and the change rate of the Q value was +5.
%, And the bending strength was 19 kgf / mm ² .

In Example 5, the L value was 4.8 μH (variation 4%), the Q value was 39 (variation 10%), the rate of change of the L value in the humidity resistance load test was + 5%, and the rate of change of the Q value was +7.
%, And the bending strength was 20 kgf / mm ² .

In Example 6, the L value was 4.7 μH (variation 4%), the Q value was 38 (variation 10%), the change rate of the L value in the humidity resistance test was + 5%, and the change rate of the Q value was +3.
%, And the bending strength was 21 kgf / mm ² .

On the other hand, in Comparative Example 1, the L value is 3.5 μH.
(Variation: 4%), Q value: 25 (Variation: 10%), L value change rate in humidity resistance load test was + 30%, Q value change rate was + 40%, and bending strength was 21 kgf / mm ² .

In Comparative Example 2, the L value is 3.7 μH.
(Variation: 7%), Q value: 25 (Variation: 12%), L value change rate in humidity resistance test was + 28%, Q value change rate was + 35%, and bending strength was 21 kgf / mm ² .

In Comparative Example 3, the L value was 5.0 μH (variation 4%), the Q value was 27 (variation 12%), the rate of change of the L value in the humidity resistance test was + 15%, and the rate of change of the Q value was +.
The bending strength was 35% and the bending strength was 23 kgf / mm ² .

In Comparative Example 4, the L value was 4.2 μH (variation 10%), the Q value was 29 (variation 20%), the change rate of the L value in the humidity resistance load test was + 7%, and the change rate of the Q value was −.
The bending strength was 33% and the bending strength was 13 kgf / mm ² .

As is clear from the above experimental results, the thermal stress strain is relaxed by performing the high temperature treatment under the conditions specified in the present invention, and as a result, the L Value improved by 28% or more, Q value improved by 40% or more, L
To obtain a laminated inductance having good characteristics such that the variation in the Q value and the Q value is 4% or less and 10% or less, and the change rate of the L value and the Q value in the moisture resistance load test are ± 10% or less and ± 30% or less, respectively. I was able to.

On the other hand, as shown in the comparative example, it was not possible to obtain the laminated inductor having desired desired characteristics even if the high temperature treatment was performed under the condition outside the range specified in the present invention.

That is, as for the treatment temperature of the high temperature treatment, as shown in Comparative Example 2, when the temperature is lower than 400 ° C., desired characteristics can be obtained in terms of L value, Q value, variations thereof, and reliability (humidity resistance load test). I couldn't. Furthermore, if the temperature exceeds 950 ° C., the desired characteristics could not be obtained due to the Q value, the variation in the Q value, and the reliability.

As for the temperature lowering rate, as shown in Comparative Example 4, when it is higher than 20 ° C./min, the desired values can be obtained in terms of L value, Q value, variations of these, and reliability (moisture resistance load test). However, the bending strength also decreased.

[0088]

As described above, according to claim 1 of the present invention, the internal conductor can be heat-treated by subjecting the sintered body to heat treatment without providing a gap between the insulator layer and the internal conductor. Between the inner conductor and the insulator layer, a large stress is applied between the inner conductor and the insulator layer to elongate the metal forming the inner conductor and rearrange the metal atoms or metal molecules. Since the stress strain generated in 1) is relaxed, stress magnetostriction does not occur during use, and a laminated inductor having good magnetic characteristics (L value, Q value, etc.) can be manufactured. Further, since the temperature lowering rate during at least the temperature lowering during the temperature rising and the temperature lowering during the heat treatment is set to 20 ° C./min or less, the sintered body is not rapidly cooled, and thus cracks are prevented from occurring and reliability (moisture resistance) is improved. It is possible to obtain a laminated inductor having high properties, bending strength, etc.).

According to the second aspect of the present invention, the thermal shock treatment for producing a temperature difference of 120 ° C. or more is performed once or more on the sintered body without providing a gap between the insulator layer and the internal conductor. Causes a large stress to be applied between the inner conductor and the insulator layer, the metal forming the inner conductor is stretched, and the metal atoms or metal molecules are rearranged, and the inner conductor and the insulator are cooled in the cooling process after firing. Since the stress strain generated between the layer and the layer is relaxed, stress magnetostriction does not occur during use, and a laminated inductor having good magnetic characteristics (L value, Q value, etc.) can be manufactured. Further, in the thermal shock treatment, the temperature rising rate at the time of temperature rising and the temperature decreasing rate at the time of temperature lowering are 20 ° C. /
Since the sintered body is set to not more than a minute, the sintered body is not rapidly heated or rapidly cooled, so that the generation of cracks is prevented, and a laminated inductor having high reliability (moisture resistance, bending strength, etc.) can be obtained.

According to the third aspect of the present invention, it is possible to obtain a sintered body having a size of 40 with respect to the sintered body, even if no space is provided between the insulating layer and the internal conductor.
By performing a high temperature treatment for 1 hour or more at a predetermined temperature between 0 ° C. and 950 ° C., a large stress is applied between the inner conductor and the insulator layer, and the metal forming the inner conductor is stretched to form a metal. Since the atoms or metal molecules are rearranged and the stress strain generated between the internal conductor and the insulator layer in the cooling process after firing is relaxed, stress magnetostriction does not occur during use, and the magnetic characteristics (L It is possible to manufacture a laminated inductor having a good value, a Q value, etc.). Further, since the temperature lowering rate at the time of lowering the temperature in the high temperature treatment is set to 20 ° C./min or less, the sintered body is not rapidly cooled, cracks are prevented from occurring, and reliability (moisture resistance, bending strength, etc.) is prevented.
It is possible to obtain a laminated inductor with high efficiency.

[Brief description of drawings]

FIG. 1 is an external view of a laminated inductor according to the present invention.

FIG. 2 is an exploded perspective view of essential parts of a laminated inductor according to the present invention.

FIG. 3 is a diagram showing experimental conditions and experimental results relating to thermal shock treatment in the first embodiment of the present invention.

FIG. 4 is a diagram showing experimental conditions and experimental results regarding high-temperature treatment in the second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main body, 2, 3 ... External electrode, 21-1 to 21-n ... Conductor pattern (inner conductor), 22-1 to 22-n ... Magnetic body sheet (insulator layer) on which a conductor pattern is formed, 23 ... Magnetic sheet (insulator layer) on which no conductor pattern is formed, 2
4 ... Through hole.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-148363 (JP, A) JP-A-4-350913 (JP, A) JP-A-4-85992 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01F 41/04

Claims (3)

(57) [Claims] 1. A laminated inductor in which a laminated body formed by laminating insulator layers having conductor patterns as internal conductors formed on the surface is fired to form a sintered body, and the sintered body serves as a laminated inductor. In the method, a step of subjecting the sintered body to a heat treatment is provided, and a temperature lowering rate at least during temperature lowering during temperature rising and lowering during the heat treatment is set to 20 ° C./minute or less. Manufacturing method of laminated inductor. 2. As the heat treatment, a thermal shock treatment with a temperature difference of 120 ° C. or more is performed on the sintered body once or more, and a temperature rising rate and a temperature lowering rate in the thermal shock treatment are 2 or more.
The method for manufacturing a laminated inductor according to claim 1, wherein the temperature is set to 0 ° C./minute or less. 3. As the heat treatment, the sintered body is subjected to a high temperature treatment at a predetermined temperature between 400 ° C. and 950 ° C. for 1 hour or more, and a temperature lowering rate at the end of the high temperature treatment is 20 ° C./minute. The method for manufacturing a laminated inductor according to claim 1, wherein the following settings are made.