JP3427007B2 - Multilayer chip coil - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil, which is superposed in the stacking direction, is embedded in an electric insulator, and a pair of external electrodes connected to both ends of the internal coil is provided. The present invention relates to a laminated chip coil having a structure conforming to. More specifically, according to the present invention, a conductor in an electrical insulator that connects both ends of a coil and an external electrode extends from the coil end to the vicinity of the external electrode in the coil axial direction, and the conductor is orthogonal to the coil axis. The present invention relates to a laminated chip coil formed of a combination of four connecting conductors formed in a direction that extends to reach four side surfaces of an external electrode. This technique is useful, for example, as an inductor element surface-mounted on a circuit board of an electronic device.

[0002]

2. Description of the Related Art In a laminated chip coil, electrically insulating layers and conductor patterns are alternately laminated, and the ends of each conductor pattern are sequentially connected to form a coil (circulation pattern) that is superposed in the laminating direction. The chip component has a structure in which it is embedded in the body and a pair of external electrodes connected to both ends of the internal coil are provided on the outer surface thereof. Nonmagnetic ceramics (a typical example is a dielectric ceramics), magnetic ceramics (a typical example is a ferrites), etc. are used as a material for forming the electrical insulating layer.

The method for forming a laminated body is roughly classified into a method in which ceramics are formed into a sheet shape, a conductor pattern is screen-printed thereon, and the ceramics sheets are laminated and pressure-bonded and integrated (sheet laminating method). ) And a ceramic pattern and a conductor pattern are alternately screen-printed to be laminated (printing lamination method).

Next, as a method of forming a coil embedded in an electric insulator, a method of sequentially printing a conductor pattern of about 1/2 turn (for example, Japanese Patent Publication No. 60-50331).
Japanese Patent Laid-Open Publication No. Hei 2-135715) or a method of sequentially printing conductor patterns for about 3/4 turns (for example, Japanese Patent Laid-Open No. 2-135715).
(See Japanese Patent Publication) and so on. In any case, a coil is formed by connecting and stacking conductor patterns of a predetermined shape, and the conductor patterns are adjacent to each other with a thin ceramic sheet in the stacking direction.

Such laminated chip coils are classified into two types depending on the relationship between the facing direction of the external electrodes and the coil axial direction (laminating direction). The first type is a structure in which the facing direction of both external electrodes is orthogonal to the coil axis direction,
This form has been common in the past. The second type is under development in recent years, and has a structure in which the facing direction of both external electrodes coincides with the coil axial direction.

An example of this second type of laminated chip coil is shown in FIG. The coil 12 is embedded in the electrical insulator 10, and the surface on which the external electrode 14 is formed is parallel to the surface on which the conductor pattern of the coil is formed (of course, the external electrodes are also formed on the four side surfaces around the surface). ). In FIG. 9, the left front surface and the right back surface correspond to each other. The lowermost layer (for example, the leftmost layer) and the uppermost layer (for example, the rightmost layer) in the stacking direction are connected to both external electrodes by forming the lead conductor 16 on the ceramics laminated from the coil conductor pattern to the external electrodes. Do that. In the case of the sheet stacking method, the lead conductor 16 can be formed by embedding a through-hole conductor in a ceramic sheet and stacking a plurality of the ceramic sheets. In the case of the printing method, the through hole is formed by printing the ceramic pattern while leaving the portion for forming the through hole, and then the conductive pattern is printed so that the conductive paste is embedded in the through hole. This process may be reversed. By repeating this step a predetermined number of times, the lead conductor is formed.

[0007]

SUMMARY OF THE INVENTION In the first form,
Depending on how the chip is placed on the mounting board (whether the coil axis direction is perpendicular or parallel to the mounting board), the direction in which the magnetic field is generated differs. It had to be implemented in the orientation. Therefore, not only an extra step of forming a marker is required, but also taping packaging is required, which causes a problem that packaging waste materials such as paper and plastic are generated every time.

On the other hand, the second type has the advantage that the direction of the magnetic field does not change even if the placement of the chip on the mounting substrate changes (that is, in principle, there is no anisotropy). However, since the lead-out conductor is formed by the through-hole conductor and is connected to the external electrode with a small area of its end, there is a problem that the connection reliability is poor.

Further, although the magnetic field generation direction does not change as described above, the problem that the inductance value changes depending on how the chip is placed remains. As a method for solving this problem, a technique of arranging the internal conductor in the center of the cross section of the chip has been proposed (see Japanese Patent Laid-Open No. 11-2624). However, this method requires a conductor in the vicinity of the coil, which connects the coil end portion to the central inner conductor, and this conductor cuts off the magnetic flux generated in the coil, so that Q is lowered and the inductance value is deteriorated. To do. Further, when the chip cross section is not square, the inductance value is changed by this method as well, so that it is limited to the case where the chip cross section is square.

An object of the present invention is to provide a laminated chip coil having a structure capable of improving the connectivity with external electrodes. Another object of the present invention is to provide a multilayer chip coil having a structure that does not need to dispose a conductor that blocks the magnetic flux of the coil, has a high Q value, and can suppress deterioration and dispersion of the inductance value. That is. Still another object of the present invention is to provide a laminated chip coil having a structure in which the inductance value does not change depending on how the chip is placed regardless of the cross-sectional shape.

[0011]

DISCLOSURE OF THE INVENTION According to the present invention, a coil in which electric insulation layers and conductor patterns are alternately laminated and ends of the respective conductor patterns are sequentially connected to each other so that the coils are superposed in the lamination direction in the electric insulator. A coil having a structure in which both ends of the coil are connected to external electrodes located at both ends of the surface of the electrical insulator by conductors in the electrical insulator, and the facing direction of the external electrodes is aligned with the coil axial direction. It is a chip coil. Here, in the present invention, the conductor in the electrical insulator that connects both ends of the coil and the external electrode includes a lead conductor extending from the coil end to the vicinity of the outer electrode in the coil axis direction, and a direction perpendicular to the coil axis from the lead conductor. And four connecting conductors extending to the four side surfaces of the external electrode. In addition, it is preferable that each connection conductor has a pattern in which a width is widened in a portion connected to the external electrode. This structure is effective for enhancing the connectivity with the external electrodes and suppressing the deterioration and variation of the characteristics.

[0012] Each connecting conductor, to set all the inductance values of those four connection conductors equally. In order to make the inductance values equal, the pattern width of the connecting conductor is changed or the length of the lead is adjusted. With this configuration, the inductance value does not change depending on how the chip is placed, and deterioration or variation in characteristics can be suppressed.

Further, according to the present invention, the conductor in the electric insulator connecting the both ends of the coil and the external electrode is a lead conductor extending from the end of the coil to the vicinity of the outer electrode in the coil axial direction, and the lead conductor to the coil. It is composed of a combination of four connecting conductors extending in the direction orthogonal to the axis and reaching only the corners of the four side surfaces of the external electrode. This configuration is also effective in improving the connectivity with the external electrodes and suppressing the deterioration and variation of the characteristics.

In these, on both sides in the electrical insulator,
The four connection conductors may be formed on the same electric insulating layer, or may be formed on different electric insulating layers and laminated. Further, a configuration may be adopted in which four connecting conductors are set as one set and a plurality of sets are stacked for each side in the electrical insulator. This configuration is also effective in further increasing the connectivity with the external electrodes.

[0015]

BACKGROUND OF THE INVENTION In a method of manufacturing a laminated chip coil, coils in which electric insulating layers and conductor patterns are alternately laminated and the ends of each conductor pattern are sequentially connected to each other so that they are superposed in the laminating direction in an electric insulator. Is formed, and both ends of the coil are drawn out by an internal conductor such as a drawing conductor. After firing the chips, the ends of the inner conductors are connected to external electrodes. By the way, the ceramics and the internal conductor shrink during firing, but since the shrinkage rate of the internal conductor is generally higher, the internal conductor slightly retracts from the surface of the ceramic (electrical insulator) after firing. Therefore, the surface of the ceramic is polished by barrel polishing to surely expose the end portion of the internal conductor to the surface. Unlike the case of a thin through-hole conductor as in the prior art, in the present invention, the connection is made by a plurality of connection conductors, and the degree of freedom in selecting the connection position with the external electrode is high,
The reliability of the connection is increased because the pattern width at the connection position is widened.

By the way, in the barrel polishing, there is a tendency that the corners of the chip are selectively shaved and the plane is hard to be shaved. In the present invention, the configuration in which the end portion of the connection conductor is connected to the corner portion of the chip is advantageous in that the grinding cost and the grinding time in the barrel polishing step are reduced.

Next, the cause of the change in the inductance value even in the conventional laminated chip coil having a structure in which the opposing directions of both external electrodes coincide with the coil axis direction is that the connecting position between the lead conductor and the external electrode depends on how the chip is placed. This is because the distance from the mounting board changes. As shown in FIG.
When the surface is in contact with the mounting board 18, the distance x between the connecting position x of the lead conductor and the external electrode and the mounting board 18 is a, but when the surface B is in contact with the mounting board, the distances are b and C. When the surface is in contact with the mounting board, the distance is c, and when the surface D is in contact with the mounting board, the distance is d. Inductance also occurs in the path through which electricity flows between the connection position between the lead conductor and the external electrode and the mounting substrate, causing variations. Therefore, in the present invention, with respect to the four connection conductors extending from the end of the lead conductor in the direction orthogonal to the coil axis and reaching the four side surfaces of the external electrode, the width of each connection conductor is changed or the length is adjusted by routing. , And the inductance value is set to the same.
This prevents the inductance value from changing depending on how the chip is placed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a manufacturing process explanatory view showing an embodiment of a laminated chip coil according to the present invention. The examples below
The sheet laminating method in which all ceramics are formed into a sheet shape and laminated will be described, but a printing laminating method in which screen printing is all performed can also be performed. As the electrical insulating material, a dielectric ceramic was used, which was made possible by adding glass to enable low temperature sintering. For example, a ceramic material is manufactured by a doctor blade method by blending and mixing a binder or the like with a dielectric material in which borosilicate glass and alumina are mixed. The ceramic sheet has a thickness of about 10 to 30 μm. This material can be fired at temperatures below the melting point of silver. Although silver was used as the material for the conductor paste, silver palladium may also be used. The conductor pattern is formed by screen-printing this conductor paste on a ceramic sheet. Such a manufacturing method is basically the same as the conventional method.

Steps (1) to (7) described below correspond to (1) to (7) in FIG. (1) First, the ceramic sheet 20 for insulating the external electrodes is prepared. On the ceramic sheet 20,
In a subsequent step, the outer surface (lower surface in the figure) is coated with a conductor paste which will be an outer conductor. If the ceramic sheet in the next step (2) can be substituted, it can be omitted. Moreover, you may laminate | stack a several sheet | seat as needed. (2) A connecting conductor 23 for connecting to an external conductor is printed on the ceramic sheet 22. This is the four connecting conductors 23 that reach four sides from the position corresponding to the through-hole conductor 25 in the next step (3). Each connection conductor 23
Are designed to have the same impedance value. Therefore, here, the pattern width is simply changed and the pattern is schematically drawn. (3) A required number (predetermined thickness) of the ceramic sheets 24 in which the through-hole conductors 25 are filled are laminated. The lead-out conductor is formed by the continuous through-hole conductors 25 of the laminated ceramic sheets 24.

The coil is formed, for example, as follows. Although a method of laminating the U-shaped conductor pattern while rotating the direction of the U-shaped conductor pattern by 90 degrees is described here, any conventionally known method may be used for this portion. (4) Through-hole conductor 27 on ceramic sheet 26
And a U-shaped conductor pattern 28 wound by 3/4 turn from the through-hole conductor 27 is printed and laminated.
The direction is changed 90 degrees, and the layers are stacked one after another and four sheets are stacked, resulting in three turns. The lamination of the ceramic sheets is repeated until the required number of turns is obtained to form the coil.

Then, a lead conductor or the like on the opposite side is formed. (5) Through-hole conductor 3 at a position corresponding to the coil end
The required number (a predetermined thickness) of the ceramic sheets 30 filled with 1 are stacked. The through-hole conductor 31 of each ceramic sheet 30 continuously forms a lead conductor. (6) Through-hole conductor 33 on ceramic sheet 32
Embedded with the ceramic sheet 3
2. Print the connection conductor 34 on the 2 for connecting to the outer conductor. This is four connecting conductors that reach four sides from the position corresponding to the through-hole conductor in the previous (5) step. The connection conductors are designed so that the impedance values are equal, and here also, a diagram adjusted by the pattern width is schematically drawn. (7) Finally, a ceramic sheet 36 for insulating the external electrodes is laminated. You may laminate | stack a several sheet | seat as needed.

After the whole is laminated and integrated as described above, it is fired to form external electrodes on both end faces (the bottom face and the top face in FIG. 1) and in the vicinity thereof. In reality, such chip parts are manufactured by a multi-cavity manufacturing method. A large number of ceramic sheets, in which a predetermined conductor pattern and through-hole conductors are regularly formed in the vertical and horizontal directions, are sequentially stacked, and the blocks (multilayer body) integrated under pressure are cut in the vertical and horizontal directions to obtain one chip each. To separate. Then, after degreasing, firing, and deburring, a conductive paste is applied and baked on both end surfaces of the chip and in the vicinity thereof to form a pair of external electrodes on both ends, and further plated to obtain the final product. .

An example of the finally obtained laminated chip coil is shown in FIG. The external electrodes 40 are formed with a certain width not only on the left and right end surfaces of the chip 42 but also on the four side surfaces in the vicinity thereof. In the present invention, the connection conductors 44 are connected at the positions of the four side surfaces of the external electrode. That is, the conductor in the electrical insulator that connects both ends of the coil 46 and the external electrode 40 to each other is a lead conductor 48 extending from the coil end portion to the vicinity of the outer electrode in the coil axis direction, and the lead conductor 48 is orthogonal to the coil axis. It is composed of a combination of four connection conductors 44 extending in the direction and reaching the four side surfaces of the external electrode 40.

In the embodiment shown in FIG. 1, the connecting conductor 44 is composed of one layer on each side, as shown in FIG. 2A. However, in the step (2) or the step (6) in FIG. It is also possible to form the connecting conductors on one side with a plurality of layers spaced apart.
This case is shown in B of FIG. When the structure has a plurality of layers, the number of connection points with the external electrodes increases, and the reliability of the connection improves.

3 to 6 are explanatory views showing a concrete design example of the connecting conductor of the laminated chip coil according to the present invention. Figure 3
Then, four connection conductors are printed by dividing them into four layers, and the respective layers of are laminated. Each ceramic sheet 50a, ..., 50
In d, the through-hole conductor 51 is embedded at the same position, and the connection conductors 52a, 52a,
..., 52d is printed. Each connection conductor 52a, ..., 52d
Adjusts the length and width so that the same inductance value can be obtained. The routing direction of these connecting conductors is preferably aligned with the winding direction of the coil. This is because the inductance value decreases when the wires are routed in the opposite direction.

FIG. 4 shows an example in which four connecting conductors are formed in one layer, as in the case of FIG. Ceramic sheet 54
Has a through-hole conductor 55 buried in a predetermined position, and the connecting conductor 56 is shaped so as to reach each corresponding side from there.
To print. The connection conductor 56 is the connection conductor 5 of FIG.
.., 52d are just superposed.

In FIG. 5, as in FIG. 3, four connecting conductors are connected to each other.
It is formed by dividing it into layers and laminating each of the layers. , 60d, the through-hole conductor 61 is embedded at the same position, and the connection conductors 62a, ..., 62d are printed so as to reach the corresponding sides from there. The lengths of the connection conductors 62a, ..., 62d are adjusted here so that the same inductance value can be obtained.

FIG. 6 shows a modification of the connection conductor of FIG.
, 64d, through-hole conductors 65 are embedded at the same positions, and connection conductors 66a, ..., 66d are printed so as to reach the corresponding sides from there. Here, the vicinity of the portion of each connecting conductor 66a, ..., 66d that reaches each side of the ceramic sheet is formed as a wide pattern. As a result, the reliability of the connection with the external electrode is significantly improved.

In addition, depending on the connecting conductor pattern, it is possible to form two or three connecting conductors in one layer of the ceramic sheet. Alternatively, as shown in FIG. 2B, a configuration may be adopted in which four connecting conductors are set as one set and a plurality of sets are stacked per one side in the electrical insulator. The structure in which a plurality of sets are laminated has not only the effect of increasing the reliability of connection but also the effect of reducing the electric resistance.

7 and 8 are explanatory views showing still another example of the structure of the connecting conductor of the laminated chip coil according to the present invention. In the example shown in FIG. 7, four connection conductors are formed in four layers, and each layer of is laminated. Each of the ceramic sheets 70a, ..., 70d has the through-hole conductor 7 at the same position.
1 is embedded, and the connection conductors 72a, ..., 72d are printed so as to reach the corresponding four corners of each ceramic sheet. This structure is also effective for optimizing the inductance value of each connection conductor. In the example shown in FIG. 8, the connection conductor is formed in one layer. The through-hole conductor 75 is embedded in the ceramic sheet 74, and the connecting conductor 76 is printed in a pattern that reaches the corresponding four corners of the ceramic sheet.

As described above, after firing, the chips are deburred by barrel polishing. At that time, the entire chip is polished, but the corners are more easily polished. Therefore, if the end portions of the connection conductor are pulled out to the corner portions as in the above embodiment, the end portions of the connection conductors are likely to appear on the chip surface. By polishing for a short time, the end portion of the connection conductor is pulled out to the surface, and highly reliable connection to the external electrode becomes possible.

By the way, generally, the portion where the conductor pattern is formed tends to have low adhesion strength when laminated. When the connection conductor is formed to reach the corners, the connection reliability is high even if the width is narrow, and there is no possibility that the adhesion strength between the layers will decrease. This effect is particularly great when the connection conductors are formed in different layers. Also in the case of the configuration in which it is pulled out to the corner portion in this way, a configuration may be adopted in which four connecting conductors are set as one set and a plurality of sets are laminated per one side in the electrical insulator.

For the above reason, the structure in which the connecting conductor is drawn out to the corner of the chip is also effective for the first type laminated chip coil in which the opposing directions of both external electrodes are orthogonal to the coil axis direction.

[0034]

As described above, according to the present invention, the conductor in the electric insulator connecting the both ends of the coil and the external electrode is
From a combination of a lead conductor extending from the coil end in the coil axis direction to the vicinity of the external electrode and four connecting conductors extending from the lead conductor in a direction orthogonal to the coil axis and reaching four side surfaces or four corners of the external electrode. Since it is a laminated chip coil having the above configuration, it is possible to improve the reliability of the connection with the external electrode.

In the present invention, since the lead conductor extending to the vicinity of the external electrode is connected to the coil end in the coil axial direction, it is not necessary to dispose a conductor for cutting off the magnetic flux of the coil. And the inductance value does not deteriorate.

Further, in the present invention, if the inductance values of all four connecting conductors are set to be equal, it is possible to prevent the inductance value from changing due to the placement of the chip in any cross-sectional shape.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing an example of a manufacturing procedure of a laminated chip coil according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an internal conductor and an external electrode of the laminated chip coil according to the present invention.

FIG. 3 is an explanatory view showing an example of a connection conductor.

FIG. 4 is an explanatory view showing another example of the connection conductor.

FIG. 5 is an explanatory view showing another example of the connection conductor.

FIG. 6 is an explanatory view showing another example of the connection conductor.

FIG. 7 is an explanatory diagram showing another example of the connection conductor.

FIG. 8 is an explanatory view showing another example of the connection conductor.

FIG. 9 is a structural explanatory view showing an example of a conventional laminated chip coil.

FIG. 10 is an explanatory diagram of variations in inductance value in a conventional laminated chip coil.

[Explanation of symbols]

40 external electrodes 42 chips 44 Connection conductor 46 coils 48 Lead conductor

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinari Noyori 5-36-11 Shinbashi, Minato-ku, Tokyo Fuji Electric Chemicals Co., Ltd. (56) References Japanese Patent Laid-Open No. 10-241941 (JP, A) Kaihei 10-284324 (JP, A) JP-A-9-312232 (JP, A) JP-A-7-272935 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01F 17 / 00 H01F 27/28

Claims (6)

(57) [Claims] 1. An electric insulating layer and conductor patterns are alternately laminated, and the ends of each conductor pattern are sequentially connected to form a coil that is superposed in the laminating direction in the electric insulator. Connected to external electrodes located at both ends of the surface of the electrical insulator by conductors in the electrical insulator,
In a laminated chip coil having a structure in which the facing direction of the external electrodes coincides with the coil axial direction, the conductor in the electrical insulator connecting both ends of the coil and the external electrodes is located near the external electrodes in the coil axial direction from the coil ends. a lead conductor extending to, Ri Do a combination of four connection conductors to reach the four sides of the external electrodes extend in a direction perpendicular from the cited lead conductor to the coil axis, each connection conductor, those four contact
Laminated chip coils, wherein Rukoto inductance of connection conductors are all set equal. 2. The laminated chip coil according to claim 1, wherein each connection conductor has a pattern whose width is widened in a portion connected to an external electrode. 3. An electrically insulating layer and a conductor pattern are alternately laminated, and the ends of each conductor pattern are sequentially connected to form a coil that is superposed in the laminating direction in the electrical insulator, and both ends of the coil are formed. Connected to external electrodes located at both ends of the surface of the electrical insulator by conductors in the electrical insulator,
In a laminated chip coil having a structure in which the facing direction of the external electrodes coincides with the coil axial direction, the conductor in the electrical insulator connecting both ends of the coil and the external electrodes is located near the external electrodes in the coil axial direction from the coil ends. 1. A laminated chip coil comprising a combination of a lead conductor extending to the lead conductor and four connecting conductors extending from the lead conductor in a direction orthogonal to the coil axis and reaching only the corners of the four side faces of the external electrode. Both external electrodes near wherein an electrical insulator in the laminated chip coil according to the four connection conductors respectively, any one of claims 1 to 3 are formed on the same electrical insulation layer. Both external electrodes near 5. Electrical insulator in four connection conductors each, multilayer chip coil according to any one of claims 1 to 3 are stacked are formed in different electrically insulating layer. 6. A plurality of sets are laminated per one side in the electric insulator, with four connecting conductors as one set.
5. The laminated chip coil according to any one of 5 above.