JPH07254528A - Laminated noise filter - Google Patents

Abstract

PURPOSE:To obtain the laminated noise filter in which delamination is hard to cause in a firing operation by a method wherein signal electrodes in two layers are laminated between grounding electrodes and the interval between the signal electrodes is set within a range of a specific multiple of the interval between the grounding electrode and the signal electrode adjacent to the grounding electrode. CONSTITUTION:A laminated noise filter 1 is laminated in such a way that insulator sheets in which grounding electrodes 5 have been formed on the surface, insulator sheets in which signal electrodes 7 have been formed on the surface and insulator sheets in which nothing has been formed on the surface are piled up. In a laminated state, the signal electrodes 7 in two layers are arranged and installed between the grounding electrodes 5 via the insulator sheets. The interval (c) between the signal electrodes 7 is set to be 0.5 to 1.1 times every interval (d) between every grounding electrode 5 and every signal electrode 7. Thereby, a stress, due to the difference in a thermal contraction rate, which is generated in a firing operation is reduced, and it is possible to prevent delamination from being caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise filter, and more particularly to a laminated noise filter.

[0002]

2. Description of the Related Art Hitherto, there has been known a laminated noise filter constituted by laminating an insulator, a ground electrode and a signal electrode. When this noise filter is used for a large current, it is necessary to reduce the DC resistance. Here, as a method of reducing the direct current resistance, a method of disposing a plurality of layers of signal electrodes between the ground electrodes can be considered. Since the signal electrodes of each of the plurality of layers are not involved in the capacitance acquisition, the distance between them tends to be as small as possible in order to reduce the product size and the manufacturing cost. As an example, the distance between the signal electrodes is 20.
The distance between the ground electrode and the signal electrode adjacent to the ground electrode may be 40 μm. That is, the distance between the signal electrodes is set to be twice the distance between the ground electrode and the signal electrode adjacent to the ground electrode. However, when the distance between the signal electrodes is reduced, the thermal contraction rate of the insulator disposed between the signal electrodes becomes significantly different from the thermal contraction rate of the signal electrodes, and the thermal contraction rate that occurs during firing. There is a problem that the stress due to the difference between the two becomes large and delamination easily occurs.

Therefore, an object of the present invention is to provide a laminated noise filter in which delamination hardly occurs during firing.

[0004]

In order to solve the above problems, a laminated noise filter according to the present invention has at least two layers of signal electrodes laminated between ground electrodes, and the distance between the signal electrodes is increased. However, the gap between the ground electrode and the signal electrode adjacent to the ground electrode is 0.5 to
It is characterized by being in the range of 1.1 times.

With the above structure, the distance between the signal electrodes becomes larger than that of the conventional noise filter, and the difference between the thermal contraction rate of the insulator disposed between the signal electrodes and the signal electrodes is suppressed. Therefore, the stress due to the difference in the thermal contraction rate generated during firing is smaller than that of the conventional noise filter,
The occurrence of delamination is suppressed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the laminated noise filter according to the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the multilayer noise filter 1 has a ground electrode 5
Is formed on the surface, the insulator sheet 2 on which the signal electrodes 7 are provided, and the insulator sheet 2 on which nothing is provided on the surface. As a material for the insulating sheet 2, for example, a dielectric ceramic such as barium titanate or lead zirconate titanate is used.

The electrodes 5 and 7 are made of a paste of Ag, Ag-Pd, Cu or the like by means of screen printing, and the insulating sheet 2 is used.
It may be formed by coating and drying on the surface of
It may be formed by means such as sputtering or vapor deposition.
The ends 5a and 5b of the ground electrode 5 are exposed on the front side and the back side of the insulator sheet 2, respectively. The ends 7a and 7b of the signal electrode 7 are exposed on the left side and the right side of the insulator sheet 2, respectively.

An insulator sheet 2 having electrodes 5 and 7 on its surface and an insulator sheet 2 having nothing on its surface are stacked. That is, between the two insulating sheets 2 having the ground electrode 5 on the surface, the two insulating sheets 2 having the signal electrode 7 on the surface are interposed between the insulating sheets 2 having no surface. It is arranged. After each insulating sheet 2 is stacked, it is shaped and fired. In the stacked state, capacitance is formed between the ground electrode 5 and the signal electrode 7.

As shown in FIG. 2, the fired noise filter 1 is provided with external input / output electrodes 10 and 11 at both ends, and external ground electrodes 12a and 12a are provided at the central portions of the front and rear side surfaces, respectively. 12b is provided. The external input / output electrode 10 is electrically connected to one end 7a of the signal electrode 7, the external input / output electrode 11 is electrically connected to the other end 7b of the signal electrode 7, and the external ground electrode 12a is grounded. The external ground electrode 12b is electrically connected to one end 5a of the electrode 5, and the external ground electrode 12b is electrically connected to the other end 5b of the ground electrode 5. FIG. 3 is an electrical equivalent circuit diagram of the noise filter 1.

The noise filter 1 having the above structure is
As shown in FIG. 4, the distance d between the ground electrode 5 and the signal electrode 7 adjacent to the ground electrode 5 is the total thickness of the two insulator sheets 2. The distance c between the signal electrodes 7 is 1
This is the thickness of the insulating sheet 2. Therefore, the signal electrode 7
The thickness of the insulating sheet 2 arranged between the layers is 4 μm, 12
6 types of μm, 20 μm, 32 μm, 40 μm, and 60 μm are used, and the remaining insulating sheet 2 having a thickness of 20 μm is used.
Was manufactured and its delamination occurrence rate was evaluated. FIG. 5 is a graph showing the evaluation result. The horizontal axis of the graph represents the ratio between the distance c and the distance d. When the thickness of the insulating sheet 2 disposed between the signal electrodes 7 was 32 μm or more, that is, when the value of c / d was 0.8 or more, the delamination occurrence rate during firing was 0%. This is because the distance c between the signal electrodes 7 is larger than that of the conventional noise filter, and the difference between the heat shrinkage ratio of the insulator disposed between the signal electrodes 7 and the heat shrinkage ratio of the signal electrodes 7 is large. It is considered that this is because the stress due to the difference in the thermal contraction rate, which is suppressed and is generated during firing, is smaller than that of the conventional filter. In the present invention, the value of c / d is 0.8.
If it is less than the above, delamination occurs, but if the occurrence rate is 10% or less, it is sufficiently practical. Therefore, a c / d value of 0.5 is also within the scope of the present invention.

On the other hand, if the thickness of the insulating sheet 2 disposed between the signal electrodes 7 is increased, the signal electrodes 7 which can be stacked can be stacked if the component size is the same as that of the conventional noise filter. The number of layers will be reduced. Therefore, the upper limit of the spacing c is set within a range in which the number of layers of the signal electrode 7 can be reduced without deteriorating the performance of the noise filter. That is, the numerical value of c / d is 1.
It is most preferable to set the upper limit to the interval c which is 1 (in the case of this embodiment, the thickness of the insulating sheet 2 disposed between the signal electrodes 7 is 44 μm).

The laminated noise filter according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist thereof. The number of signal electrodes provided between the ground electrodes is not limited to two layers, but three layers
It may be more than one layer. Further, the number of insulating sheets provided between the signal electrodes is not limited to one, and two or more insulating sheets may be combined.

Further, the noise filter is not limited to one formed by stacking insulating sheets. For example, the noise filter may be manufactured by the manufacturing method described below. A paste-like insulator material is applied by means such as screen printing and dried to form an insulator film, and then a paste-like conductor material is applied to the surface of the insulator film and dried to form a signal electrode (or Forming a ground electrode). A noise filter having a laminated structure is obtained by sequentially applying the layers in this manner.

[0014]

As is apparent from the above description, according to the present invention, the distance between the signal electrodes is 0.5 to 0.5 times the distance between the ground electrode and the signal electrode adjacent to the ground electrode.
Since it is 1.1 times, the distance between the signal electrodes is larger than that of the conventional noise filter, and the difference between the thermal contraction rate of the insulator disposed between the signal electrodes and the thermal contraction rate of the signal electrodes is suppressed. To be done. As a result, the stress due to the difference in the thermal contraction rate that occurs during firing becomes smaller than the conventional noise filter,
A laminated noise filter in which delamination does not easily occur can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a laminated noise filter according to the present invention.

FIG. 2 is a perspective view showing the appearance of the noise filter shown in FIG.

FIG. 3 is an electrical equivalent circuit diagram of the noise filter shown in FIG.

4 is a partially enlarged structural view of the noise filter shown in FIG.

FIG. 5 is a graph showing the evaluation result of the delamination occurrence rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Multilayer noise filter 2 ... Insulator sheet 5 ... Ground electrode 7 ... Signal electrode c ... Distance between signal electrodes d ... Distance between ground electrode and signal electrode

Claims (1)

[Claims] 1. A noise filter formed by laminating an insulator, a ground electrode and a signal electrode, wherein at least two signal electrodes are laminated between the ground electrodes,
The distance between the signal electrodes is 0.5 of the distance between the ground electrode and the signal electrode adjacent to the ground electrode.
A laminated noise filter characterized by being in the range of up to 1.1 times.