JP2004088969A - Ceramic coil for brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound ceramic coil which lessens distortion occurring in a conductor line by preventing cracks or delamination. <P>SOLUTION: In a ceramic coil for a brushless motor which is made by printing a plurality of coil patterns on one side of a ceramic green sheet and stacking the ceramic green sheets in a plurality of numbers and sintering them, the coil patterns are constituted by winding conductor lines spirally at specified line intervals, and the conductor line of the coil pattern is provided in the position of overlapping with the section between the conductor lines of other coil patterns which overlap each other in a stacking direction and adjoin each other. <P>COPYRIGHT: (C)2004,JPO

Description

【００６１】
表１に示すように、本発明のセラミックコイル（千鳥配置）は比較例の場合と比べて変形量を１／２以下と著しく低減している。さらにカウンターを設けたものは、厚みが増加するものの、更に変形を低減することが出来た。
【００６２】
さらに工具顕微鏡での断面観察倍率を５００倍として観察したところ、本発明のセラミックコイルではデラミネーションやクラックなどの構造結果は見られなかったが、比較例のものではデラミネーションやクラックが発生した。また、比較例のものではセラミックコイルが積層方向にくの字状にずれて形成されていた。
【００６３】
以上本発明のセラミックコイルを永久磁石モータの固定子に適用した例に基づいて、本発明を説明したが、本発明は界磁コイル以外のスパイラルコイルを有するコイル部品例えばインダクターなどにも適用できることは明らかであろう。
【００６４】
【発明の効果】
本発明のセラミックコイルは、クラックやデラミネーションの生じないまた導体パターンの潰れや歪みを低減した健全なものなので、モータのように加重や振動の加わる用途に応用できるものとなった。
【図面の簡単な説明】
【図１】本発明のセラミックコイルを用いた永久磁石モータの平面図である。
【図２】本発明のセラミックコイルを用いた永久磁石モータを印刷回路基板上に取り付けた状態を示す断面図である。
【図３】永久磁石モータに用いている固定子（セラミックコイル）の外観斜視図である。
【図４】本発明の一実施例に係る固定子（セラミックコイル）における界磁コイルの結線を示す結線図である。
【図５】図３に示す固定子（セラミックコイル）の分解斜視図である。
【図６】固定子の裏面にある第一の導体パターンの斜視図である。
【図７】コイルパターンを印刷形成したセラミックグリーンシートの平面図である。
【図８】コイルパターンを印刷形成した第二のセラミックグリーンシートの平面図である。
【図９】コイルパターンの位置関係を示す平面図である。
【図１０】コイルシート積層品の断面図である。
【図１１】焼結後の本発明によるセラミックコイル（例えば固定子）の断面図である。
【図１２】セラミック部（カウンター）を設けたセラミックグリーンシートの平面図である。
【図１３】セラミック部（カウンター）を設けたコイルシート積層品の断面図である。
【図１４】セラミックグリーンシートを積層した比較例の断面図である。
【図１５】焼結後の比較例のセラミックコイルの断面図である。
【図１６】本発明の一実施例に係るセラミックコイルにおけるコイルパターンの配置関係を示す断面図である。
【符号の説明】
１０　　　　　　　　　　　　固定子（セラミックコイル）
１５　　　　　　　　　　　　ハンダ
１９　　　　　　　　　　　　開孔
２０　　　　　　　　　　　　外部端子用セラミックグリーンシート
３０　　　　　　　　　　　　コイルシート積層品
４０，５０，４０′，５０′，６０、８０　　セラミックグリーンシート
２２，２３，２４，２５　　　　　　　　　　接続端子
２６　　　　　　　　　　　　第二の導体パターン
４２，５２，４２′，５２′、６２　　　　　　　　　　　　　　　　コイルパターン
４５　　　　　　　　　　　　セラミック部（カウンター）
７２，７３，７４　　　　　　　　　　　　　　　　　　　　　　　　第一の導体パターン
８２　　　　　　　　　　　　コイルパターン
１８　　　　　　　　　　　　軸受
９０　　　　　　　　　　　　永久磁石回転子
９１　　　　　　　　　　　　永久磁石
９５　　　　　　　　　　　　回転軸
１００　　　　　　　　　　永久磁石モータ
２００　　　　　　　　　　印刷回路基板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ceramic coil produced by laminating and sintering a large number of printed conductor lines forming a coil pattern on a ceramic green sheet, and more particularly to a ceramic coil applicable to a field coil of a rotating machine. It relates to coils.
[0002]
[Prior art]
As a motor used in small electronic equipment, a multilayer body is formed by printing and forming a coil pattern to be a field coil on a ceramic green sheet using a lamination technology of a ceramic sheet and an electrode pattern, such as a multilayer capacitor and a multilayer inductor. A combination of a stator consisting of a ceramic coil integrally sintered and a permanent magnet rotor is disclosed in Japanese Patent Application Laid-Open Nos. 64-59902 and 6-38460.
[0003]
The ceramic material constituting the ceramic green sheet includes aluminum nitride and alumina as high-temperature materials, borosilicate glass and alumina glass as low-temperature materials, and tungsten and low-temperature materials as high-temperature materials. Metals or alloys, such as gold, silver, copper, nickel, etc., are used as the material of the conductor line forming the coil pattern.
[0004]
Such a ceramic coil has heat resistance and a high thermal conductivity, so that it has stable characteristics against environmental temperature differences and heat generated by the motor itself, and uses a ceramic coil formed in a plurality of layers with an adhesive material or the like. Therefore, the electric connection between the ceramic coils can be made at low cost and with high reliability.
[0005]
When a drive current is supplied to the ceramic coil, a magnetic field is generated, and this magnetic field acts on the magnetic field of the magnet of the rotor of the motor to generate an electromagnetic force. As a result, a torque is generated between the rotor and the ceramic coil, and as a result, the rotor rotates a predetermined angle. Then, by sequentially applying the drive current to the coil poles of each phase, the rotor continuously rotates. At this time, in order to obtain high torque characteristics, it is necessary to wind the ceramic coil at least several tens of turns.
[0006]
However, in order to obtain high torque characteristics, the ceramic coil is formed in multiple layers, and the ceramic green sheet interposed between the coils is made thinner so as to minimize the increase in thickness due to the multilayering, thereby forming a coil pattern. The effect of the thickness of the conductor line cannot be ignored.
[0007]
In the ceramic coil, it is general that the coil pattern is spirally formed by winding a plurality of turn conductor lines in a plane so as to increase the number of turns. For example, in a magnetic disk drive motor of a hard disk, for example, a conductor line having a conductor width of 80 to 240 μm is wound at a spacing of approximately 80 to 120 μm for 2 to 6 turns to form a coil pattern. The thickness of the ceramic green sheet between the coil patterns is set to 15 to 20 μm. A large number of such ceramic green sheets are laminated as shown in FIG. 14, and the coil patterns formed on the respective ceramic green sheets are overlapped to apply pressure to form an integrated laminate. The coil patterns are connected to each other through through holes formed in the green sheet, and are sintered to form a ceramic coil of several tens of turns. As shown in FIG. 15, the cross section of such a ceramic coil has a step between a portion where the coil patterns 82 overlap in the laminating direction (coil forming portion) and a portion where the coil is not formed. It will be formed thin. Also, in the coil forming portion, a portion where the coil pattern 82 overlaps in the laminating direction and a portion where the coil pattern 82 does not overlap occur. The reason for the occurrence of such a level difference or a depression is that the deformability with respect to the pressure of the ceramic green sheet and the coil pattern is greatly different, and when the laminate is pressed, the coil forming portion and the coil non-forming portion are uniformly formed. This is because it is difficult to apply pressure.
[0008]
When pressure is applied to such an extent that the non-coil-forming portion, where the pressure is not easily applied, does not peel off, high pressure acts on the coil pattern overlapping in the stacking direction in the laminate, and the density of the ceramic green sheet in that portion decreases. Higher than the formation. In addition, cracks may occur or the coil pattern may be displaced (distorted) in the surface direction of the ceramic green sheet so as to release the internal stress generated in the portion. For this reason, it has been difficult to accurately form the effective line length portion of the ceramic coil that contributes to the torque characteristics of the motor, or the coil pattern may be broken if the deviation is significant.
[0009]
In the non-coiled portion, the pressure is not sufficiently applied, and the density is low and the adhesion between the ceramic green sheets is weak. When such a laminate is sintered, structural defects such as delamination are likely to occur, and the density in the laminate is uneven, and the shrinkage ratio of each part is different.
[0010]
As a method for improving such a problem, Japanese Patent Application Laid-Open No. 2001-126951 discloses a method in which a printed surface excluding a surface portion corresponding to a printed pattern of an internal electrode is superimposed on a sheet surface of a ceramic green sheet on which an internal electrode is printed. It discloses that a ceramic plate is printed with a predetermined thickness so as to fill a step between an internal electrode and a ceramic green sheet, and a plurality of the pastes are laminated to obtain a multilayer ceramic component.
[0011]
[Problems to be solved by the invention]
According to the method disclosed in Japanese Patent Application Laid-Open No. 2001-126951, although the adhesion between the coil-free portion and the density difference between the coil-forming portion and the coil-forming portion can be reduced, the ceramic coil for motors has a coil-forming portion. However, there remain problems such as deformation caused by a difference in density and adhesion between portions, and displacement of a coil pattern.
[0012]
Therefore, an object of the present invention is to provide a sound ceramic coil that prevents cracks and delamination and reduces distortion generated in a conductor line.
[0013]
[Means for Solving the Problems]
The present invention provides a ceramic coil for a brushless motor in which a plurality of coil patterns are printed and formed on one surface of a ceramic green sheet, and a plurality of the ceramic green sheets are laminated and sintered integrally. This is a ceramic coil for a brushless motor, which is spirally wound with a line interval, and in which a conductor line of the coil pattern overlaps in a laminating direction and is overlapped with an adjacent conductor line of another coil pattern.
[0014]
Here, a state in which the conductor line of the coil pattern is provided in the overlapping position between the conductor lines of another adjacent coil pattern that overlaps in the stacking direction will be described. The coil cross-sectional view shown in FIG. 16 shows an arrangement relationship of two coil patterns 42a and 52a formed on different ceramic green sheets in a laminate. The coil patterns 42a and 52a are wound with a predetermined interval L, for example, two turns. Here, for convenience, the coil pattern 42a shown as a cross section of the two conductor lines is shown as conductor lines 42a1 and 42a2, respectively, and the coil pattern 52a is shown as conductor lines 52a1 and 52a2, respectively.
[0015]
For example, the conductor line 42a1 of the coil pattern 42a is stacked and disposed at a position overlapping in the stacking direction between two conductors (L portions) of the conductor lines 52a1 and 52a2 formed on different ceramic green sheets. In FIG. 16, the line width W of the conductor line 42a1 is arranged between the two conductors of the conductor lines 52a1 and 52a2. However, if the widthwise central portion of the conductor line is between the two conductor lines. It is preferable that at least 0.3 times or more the total width W of the conductor line be overlapped between the two conductors (L portion) of the conductor line formed on the ceramic green sheet in the laminating direction so that the density and the adhesion force are reduced. It is preferable because it is possible to solve the problem caused by the non-uniformity and to make the coil patterns adjacent to each other in the stacking direction function so as to prevent the coil patterns from shifting. It is also within the scope of the present invention that part of the conductor lines of the coil pattern adjacent to each other in the laminating direction overlap.
[0016]
In the ceramic coil of the present invention, it is preferable that the coil pattern is provided on one surface of the ceramic green sheet in a rotationally symmetric manner. It is more preferable to laminate a plurality of ceramic green sheets on which ceramic paste is printed on a portion where the coil pattern is not formed, on one surface of the ceramic green sheet on which the coil pattern is formed by printing, and sinter together.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
A permanent magnet motor (brushless motor) using the ceramic coil of the present invention for a stator will be described in detail below with reference to the drawings. 1 and 2 show the entirety of a permanent magnet motor using a ceramic coil according to an embodiment of the present invention. FIG. 1 is a plan view, and FIG. 2 is a state in which the permanent magnet motor is mounted on a printed circuit board. FIG.
[0018]
The permanent magnet motor 100 includes a stator 10 composed of a plate-shaped ceramic coil having a plurality of field coils therein, and a permanent magnet rotor 90 held by a rotating shaft 95 mounted at the center of rotation. The printed circuit board 200 has an opening through which the rotating shaft 95 passes, and the stator 10 is fixed on the printed circuit board 200 with solder or the like so as to straddle the opening.
[0019]
A connection terminal with a power supply printed wire (not shown) on the printed circuit board 200 is formed on the mounting surface side of the stator 10, and Pb-free solder such as Sn-Ag or Sn-Ag-Cu is used. It is preferable because the stator 10 can be easily mounted on the printed circuit board 200 with the solder 15. Further, it is possible to form the connection terminal on the side opposite to the mounting surface and to perform solder connection with the printed wire and the conductive wire, but in this case, a fixing means such as bonding to the printed circuit board is required. .
[0020]
The stator 10 has an opening 19 at a position corresponding to the rotation center of the permanent magnet rotor 90, and a bearing 18 is attached to the opening 19, and the rotating shaft 95 is rotatable by the bearing 18. It is held by the stator 10. The permanent magnet rotator 90 is provided with a permanent magnet 91 such that the surface thereof faces a stator made of a plate-shaped ceramic coil.
[0021]
The permanent magnet 91 used here is a rare earth sintered magnet such as a Nd-Fe-B sintered magnet or a Sm-Co sintered magnet, or a rare earth bond such as Nd-Fe-B, Sm-Fe-N or Sm-Co. Use a permanent magnet material with high holding power, such as a magnet or a sintered ferrite magnet. Preferably, the magnet thickness can be reduced by using a permanent magnet material having a specific coercive force Hij higher than the residual magnetic flux density Br. As the shape of the permanent magnet 91, a ring shape or a fan shape obtained by dividing the ring can be used. In the permanent magnet 91, it is desirable that the N pole and the S pole are rotationally symmetric with respect to the motor rotation center.
[0022]
FIG. 3 is an external perspective view of the stator 10 used in the permanent magnet motor 100. FIG. The stator 10 is a plate-like ceramic coil having a substantially square shape, and has a thickness of several hundred μm. Connection terminals 22, 23, 24, and 25 are provided at four corners of one end face, respectively. The stator 10 has an end face on the side where the connection terminal is provided facing the mounting surface of the printed circuit board 200, and the connection terminal is soldered to a power supply printed wire (not shown) on the printed circuit board. Thus, power is supplied to the field coil of the permanent magnet motor 100, and the printed circuit board 200 and the stator 10 are fixed. The four connection terminals are preferably provided on the end face of the stator 10 at rotationally symmetric positions with respect to the opening 19 at the center thereof.
[0023]
The field coils provided inside the stator 10 have six field coils as shown in FIG. 4, and three sets of field coils configured by connecting each two field coils in series. It is preferable that the magnetic coils correspond to the respective phases of the motor and have three phases in total. One end of each of these three sets of field coils is connected to each of three connection terminals 22, 23, and 24 of the four connection terminals, and the other ends of these three sets of field coils are common. It is desirable to be connected to the connection terminal 25.
[0024]
In order to explain the structure of the stator 10, FIG. 5 shows an exploded perspective view of a ceramic coil used for the stator. FIG. 5 shows a ceramic green sheet laminate before sintering, which includes a ceramic green sheet 20 for external terminals provided with a plurality of connection terminals on one surface and a coil sheet laminate 30 having a plurality of field coils. Become. An opening 19 penetrating in the laminating direction is provided at a substantially central portion of the laminated ceramic green sheet product.
[0025]
The coil sheet laminated product 30 is formed by laminating 10 to 20 ceramic green sheets 40 to 50 ′ and 60 each having a substantially square shape. A plurality of fan-shaped coil patterns 42 to 52 'and 62 mainly composed of Ag paste are formed on the sheets 40 to 50' and 60 by printing in a rotationally symmetric manner with respect to the openings 19 thereof.
[0026]
There are two types of ceramic green sheets on which coil patterns are formed. Here, the coil patterns 42, 42 'attached to the odd-numbered ceramic green sheets 40, 40' from the top are counterclockwise inward from the outer periphery. The coil is spirally wound and attached to the even-numbered ceramic green sheets 50 and 50 ′ from the top (the even-numbered ceramic green sheets may be referred to as “second ceramic green sheets” in this specification). The patterns 52, 52 'are swirling clockwise from the outer periphery toward the inside. The coil pattern 62 on the lowermost ceramic green sheet 60 has the same coil pattern as the odd-numbered sheet in this example.
[0027]
Here, six coil patterns are printed and formed on each ceramic green sheet, and the coil patterns formed on each ceramic green sheet are a, b, c, d in the clockwise order from the one at the left end in FIG. , E, f. The coil patterns formed on the ceramic green sheet 40 are referred to as 42a, 42b, 42c,... 42f, and the coil patterns of the second ceramic green sheet 50 thereunder are referred to as 52a, 52b,.
[0028]
In order to show the structure of the coil pattern printed on the ceramic green sheet, a plan view of the coil patterns 42a, 42b, 42c,... 42f of the ceramic green sheet 40 is shown in FIG. FIG. 8 shows a plan view of the coil patterns 52a, 52b,... 52f. The coil patterns of the odd-numbered ceramic green sheets from the top are the same as those shown in FIG. 7, and the coil patterns of the even-numbered ceramic green sheets from the top are the same as those shown in FIG.
[0029]
In the ceramic green sheet 40, through holes are formed in the thickness direction of the ceramic green sheet at the inner ends of the coils of the coil patterns 42a, 42c, and 42e. It passes through the conductor to the surface. Further, through holes are formed in the thickness direction of the ceramic green sheet at the outer ends of the coils of the coil patterns 42b, 42d, and 42f, and from the outer end of each coil pattern to the other surface of each sheet through the through holes. Through a conductor. Hereinafter, through holes and conductors are similarly formed in the odd-numbered ceramic green sheets. In the even-numbered ceramic green sheets 50, through-holes are formed in the thickness direction of the ceramic green sheets at the outer ends of the coils of the coil patterns 52a, 52c, and 52e. Through the conductor to the other side of each sheet. Further, through holes are formed in the thickness direction of the ceramic green sheet at the inner ends of the coils of the coil patterns 52b, 52d, and 52f, and from the inner end of each coil pattern to the other surface of each sheet through the through holes. Through a conductor. Hereinafter, even-numbered ceramic green sheets are similarly formed with through holes and conductors.
[0030]
When the ceramic green sheets 40 to 50 ', 60 on which the fan-shaped coil patterns, the through holes and the conductors are formed as described above are stacked as shown in FIG. 5 to form a coil sheet laminate 30, coil patterns 42a, 52a,. ′ A, 52′a, 62a overlap, coil patterns 42b, 52b,..., 42′b, 52′b, 62b overlap, and similarly, the coil patterns at the corresponding positions of each ceramic green sheet overlap. Become. The inner end of the coil pattern 42a is connected to the inner end of the coil pattern 52a by a conductor and a through hole provided through the ceramic green sheet 40 at the inner end of the coil pattern 42a. The outer end of the coil pattern 52a is connected to the outer end of the underlying coil pattern by a conductor and a through hole provided through the ceramic green sheet 50 at the outer end of the coil pattern 52a. Similarly, the coil patterns of the upper and lower ceramic green sheets are connected to each other to form a coil in which the coil patterns 42a, 52a,... 42'a, 52'a, and 62a are connected. At the same time, coils are similarly formed for the other five coil patterns.
[0031]
The first conductor patterns 72, 73, and 74 are formed by printing on the side of the lowermost ceramic green sheet 60 opposite to the side on which the coil pattern 62 is formed, as shown in a perspective view in FIG.
[0032]
FIG. 6 is a perspective view of the ceramic green sheet 60 viewed from the opposite side (bottom side) to FIG. The first conductor patterns 72, 73, 74 connect between the coil patterns on the upper surface of the ceramic green sheet 60. That is, the first conductor pattern 72 is formed of a conductor extending from the inner end of the coil pattern 62a of the ceramic green sheet 60 to the back surface of the sheet through the through hole formed therein and the outer end of the coil pattern 62d. A conductor is connected through the through-hole formed there to the back of the sheet. The first conductor pattern 73 connects the outer end of the coil pattern 62b to the inner end of the coil pattern 62e, and the first conductor pattern 74 connects the outer end of the coil pattern 62f to the inner end of the coil pattern 62c. are doing.
[0033]
The first conductor patterns 72, 73, 74 connect two sets of field coils that are 180 ° apart with respect to the center of rotation or opening 19, so that each first conductor pattern surrounds the opening 19. The arc extends 180 ° or more. As is clear from FIG. 6, each first conductor pattern has two steps extending along two circumferences having different radii. The first conductor patterns are provided at least partially overlap with each other in the angular direction.
[0034]
, 42'a, 52'a, 62a are connected to the coil patterns 42d, 52d, ..., 42'd, 52'd, 62d. Are connected in series by the first conductor pattern 72. That is, one set of field coils is formed by two field coils. The same applies to the other first conductor patterns 73 and 74.
[0035]
In the case of a ceramic coil for a three-phase motor as in the present embodiment, each of the field coils is formed at an opening angle of less than 60 ° and 40 ° or more, preferably about 50 °. The field coil width is set to an appropriate value in relation to the width of the permanent magnet used for the opposing rotor. However, when the number of magnetic poles of the permanent magnet is set to six, each magnetic pole is completely replaced by each field coil. The size is 40 ° or more and less than 60 ° as a size that can be covered by the magnetic pole and does not cover the adjacent magnetic poles at the same time. The number of turns per ceramic green sheet of the field coil is suitably 2 to 4 times. It is preferable to increase the number of windings in order to increase the driving torque. However, if the number of windings is increased, the resistance increases and the current flowing through the coil decreases.
[0036]
In this embodiment, when the odd-numbered ceramic green sheets, for example, 40 coil patterns 42a and the even-numbered ceramic green sheets, for example, 50 coil patterns 52a are overlapped, the conductors of the coil pattern 42a are adjacent to the coil pattern 52a. It is provided at a position on the ceramic green sheet 40 corresponding to between the conductors, and is configured as shown in FIG.
[0037]
In FIG. 9, the upper coil pattern 42a is indicated by a solid line, and the lower coil pattern 52a is indicated by a broken line. The conductor forming each linear portion and each arc portion of the coil pattern 42a is located between or beside two conductors forming each linear portion and each arc portion of the coil pattern 52a, The conductor of the coil pattern 42a and the conductor of the coil pattern 52a do not overlap. When viewed from each conductor of the coil pattern 52a, the relationship with each conductor of the coil pattern 42a is the same. When the ceramic green sheets 40, 50,..., 40 ', 50', 60 are laminated as described above, the cross section taken along line 10-10 in FIG. 9 is an odd-numbered ceramic green sheet as shown in FIG. The coil pattern conductors of the sheets 40,... 40 ', 60 and the coil pattern conductors of the even-numbered ceramic green sheets 50,.
[0038]
In the embodiment described above, of the ceramic green sheets forming the coil sheet laminated product, the side opposite to the surface on which the fan-shaped coil pattern of the ceramic green sheet 60 most opposite to the external terminal ceramic green sheet is formed. , A plurality of first conductor patterns were formed. A coil sheet laminated product using a ceramic green sheet having no fan-shaped coil pattern in place of the ceramic green sheet 60 and having a first conductor pattern formed on a surface of the sheet facing the ceramic green sheet 50 '. It can also be.
[0039]
An external terminal ceramic green sheet 20 is stacked on a stack of a plurality of ceramic green sheets having a plurality of coil patterns. The external terminal ceramic green sheet 20 has printed connection terminals 22, 23, 24, 25 and a second conductor pattern 26 on the side opposite to the side facing the coil sheet laminate. The four connection terminals 22, 23, 24, and 25 are provided at four corners on one end surface of the ceramic green sheet for external terminals 20. The second conductor pattern 26 is provided in an annular shape so as to surround the opening 19, and the second conductor pattern 26 is connected to the connection terminal 25 by another conductor pattern.
[0040]
Each of the connection terminals 22, 23, and 24 has an extension, and the tip of the extension extends to a position corresponding to the outer ends of the fan-shaped coil patterns 42 a, 42 c, and 42 e printed on the ceramic green sheet 40. . The second conductor pattern 26 at the center has a portion extending in the radial direction, and the tip ends thereof correspond to the inner ends of the fan-shaped coil patterns 42b, 42d, and 42f printed on the ceramic green sheet 40. Extending to
[0041]
In the ceramic green sheet for external terminals 20, through holes are formed at the ends of the extending portions extending from the connection terminals 22, 23, and 24 and at the ends of the conductor patterns extending in the radial direction from the second conductor pattern. The connection terminals 22, 23, and 24 and the second conductor pattern 26 are electrically connected to the back of the external terminal ceramic green sheet 20 by conductors passed through the through holes. By laying the external terminal ceramic green sheet 20 on a laminated ceramic green sheet having a coil pattern, the connection terminals 22, 23, and 24 are connected to the outer ends of the coil patterns 42a, 42c, and 42e, respectively. The inner ends of the patterns 42b, 42d, and 42f are connected to the connection terminals 25 via the second conductor patterns 26. As a result, the connection shown in FIG. 4 is obtained.
[0042]
The external terminal ceramic green sheet 20 and the coil sheet laminated product 30 in which 10 to 20 ceramic green sheets 40, 50,..., 40 ', 50', 60 having a plurality of coil patterns are laminated are laminated. After being integrated by applying pressure, sintering is performed. By sintering, these ceramic green sheets are formed into an integral sintered plate-shaped ceramic coil as shown in FIG. The upper surface of the stator made of the plate-shaped ceramic coil shown in FIG. 3 is covered with an insulating layer except for the surfaces of the connection terminals 22, 23, 24 and 25. It is preferable that the end face of the stator where the first conductor patterns 72, 73, 74 are provided is covered with an insulating layer.
[0043]
The laminated ceramic green sheets are sintered to form a ceramic coil (stator 10) in which the coil pattern conductor is surrounded by ceramic. The laminated ceramic green sheets are united by sintering, and the conductor having a substantially trapezoidal cross section becomes an elliptical cross section, as shown in a cross-sectional view in FIG.
[0044]
As shown in FIGS. 9 and 10, two coil pattern conductors formed on the odd-numbered ceramic green sheets and two coil pattern conductors formed on the even-numbered ceramic green sheets are provided on the mating sheet. The conductors having an elliptical cross-section of the sintered ceramic coil after crimping do not overlap at the same position, so to speak, in a staggered arrangement.
[0045]
By arranging the coil pattern conductors in a staggered manner in the ceramic in this way, it is possible to reduce the collapse and distortion of the conductors when applying pressure before or during sintering, to suppress the occurrence of delamination, It can be a ceramic coil.
[0046]
The ceramic green sheet is made of ZnO-MgO-SiO ₂ A material whose main component is SiO ₂ -B ₂ O ₃ -Al ₂ O ₃ Al-based material, Al ₂ O ₃ -CaO-SiO ₂ -MgO-B ₂ O ₃ Al-based material, Al ₂ O ₃ -SiO ₂ A binder, a plasticizer and a solvent are added to a material or the like containing -SrO as a main component, and the thickness is set to 10 m to several tens m by a doctor blade method or the like. A coil pattern is printed and formed on the ceramic green sheets with an Ag paste or the like, and then laminated, and integrated by applying a pressure of 9.8 MPa to 19.6 MPa. Then, it is sintered at a temperature of about 850 ° C. to 1000 ° C. in an appropriate atmosphere. Since such a large pressure is applied to integrate the conductors, if the portion where the conductor lines overlap is large, the pressure is applied to the conductor as it is, and the conductor is greatly deformed. Further, since the ceramic at that portion becomes thin, cracks may occur in the ceramic between the conductors. However, by positively shifting the position of the coil pattern conductor as in the present invention, the thickness of the ceramic interposed therebetween increases, so that the ceramic serves as a buffer and does not cause cracks or the like.
[0047]
In the ceramic coil of the present invention, a ceramic portion made of substantially the same material as the ceramic green sheet (hereinafter, may be referred to as a “counter”) is provided in a region where no coil pattern exists on the upper surface of the ceramic green sheet before sintering. Is more preferably formed.
[0048]
FIG. 12 is a plan view of a ceramic green sheet in which the ceramic portion is formed in a region where no coil pattern exists. In FIG. 12, the ceramic portion 45 (counter) is hatched with fine dots. A ceramic portion 45 is provided at an empty portion in the center of the coil pattern and around the coil pattern.
[0049]
The ceramic portion 45 is formed by mixing a dielectric powder constituting a ceramic green sheet with a resin (ethyl cellulose), a plasticizer (dimethyl phthalate), and a solvent (BCA, ethanol, butanol) in a predetermined amount, and forming a dielectric paste. It is formed by printing. The ceramic portion 45 is preferably provided on the entire surface of the ceramic green sheet except for the coil pattern portion. It is desirable that the thickness of the ceramic portion be approximately 50 to 100% of the conductor thickness of the coil pattern.
[0050]
FIG. 13 is a cross-sectional view showing a state in which a plurality of ceramic green sheets on which the ceramic portions 45 are formed are stacked, and before the pressure bonding. Here, the interval between the coil pattern conductors is about 100 μm at substantially the same level as the conductor width, so that it is not necessary to provide a ceramic portion between the coil pattern conductors. In this way, by providing the ceramic portion 45, the internal pressure distribution can be made uniform when the ceramic green sheets are pressed, and the adhesion when the ceramic green sheets are stacked is further improved, and the flatness of the ceramic coil is further improved. It is possible to prevent the coil conductor from being crushed or distorted.
[0051]
In addition, since the difference in thickness between the coil-formed portion and the coil-unformed portion is reduced and the flatness of the ceramic green sheet is improved, undesired deformation, delamination, and cracks can be prevented.
[0052]
The ceramic portion 45 need not be provided on all ceramic green sheets, and may be provided only on even-numbered layers or only on odd-numbered layers, for example, depending on the thickness of the green sheet, the conductor thickness of the coil pattern, and the number of layers. It should be provided. It is within the scope of the present invention to provide a ceramic portion between the coil pattern conductors as needed.
[0053]
【Example】
On one surface of the ceramic green sheet, a coil pattern is printed and formed with Ag paste, and a total of 11 sheets are alternately laminated so that the coil patterns are staggered as shown in FIGS. A pressure of 10.8 MPa was uniformly integrated over 600 seconds to obtain a ceramic green sheet laminate shown in FIG. Then, the temperature is raised to about 900 ° C. in about 13 hours in a firing furnace in an air atmosphere, maintained at that temperature for about one and a half hours, and then cooled to room temperature for about 5 hours to perform sintering. Was 8 mm × 8 mm to produce a ceramic coil of the present invention.
[0054]
The ceramic green sheet is mainly composed of oxides of Al, Si, Sr, and Ti. ₂ O ₃ , SiO ₂ , SrO, TiO ₂ When converted to a total of 100% by mass, Al ₂ O ₃ 50% by mass in conversion, SiO ₂ 36 mass% in conversion, 10 mass% in SrO conversion, TiO ₂ Contains not more than 4% by mass of Al, Si, Sr, and Ti, and Bi as a subcomponent with respect to 100% by mass ₂ O ₃ A dielectric ceramic containing 2.5% by mass of Bi in terms of Bi was used, and a binder, a plasticizer and a solvent were added thereto and mixed, and the viscosity was adjusted to obtain a ceramic slurry.
[0055]
Using this ceramic slurry, a ceramic green sheet having a thickness of 20 μm was produced by a known sheet forming method such as a doctor blade method. Using an Ag paste, a coil pattern shown in FIG. 7 and a coil pattern shown in FIG. 8 were printed and formed on one surface of the ceramic green sheet to obtain two types of sheets. The fan-shaped coil pattern had an angle viewed from the center of the ceramic green sheet of about 50 °, the thickness of the coil pattern conductor was 20 μm, the conductor width was 200 μm, and the interval between the conductors was 100 μm.
[0056]
The thickness and the amount of deformation of the ceramic coil thus manufactured were measured in ten pieces, and the results are shown in Table 1 as “the present invention (staggered arrangement)”. The thickness was measured by using a tool microscope with a magnification of 50 times and the thickness of the thickest portion and the thickness of the thinnest portion were measured by using a tool microscope with a magnification of 50 times. This was evaluated for 16 cross sections at 0.5 mm intervals in one sample. Hereinafter, the thickness and the deformation amount are similarly evaluated.
[0057]
Next, a part of the coil pattern was formed on the ceramic green sheet shown in FIGS. 7 and 8 produced in the above process, using a dielectric paste obtained by forming the same dielectric material powder as that used for the ceramic green sheet. A ceramic part (counter) was formed by screen printing as shown in FIGS. Each counter was formed at a distance of about 30 μm from the end of the coil pattern, and had a uniform thickness of about 15 μm. Using the ceramic green sheets on which the counters were formed as described above, a total of 11 sheets were laminated in the same manner as in the above example to obtain a ceramic green sheet laminated product. This was pressed and sintered as described above to obtain a ceramic coil.
[0058]
Separately, a ceramic coil of a comparative example was manufactured. A coil pattern is formed on the ceramic green sheet in the same manner as in the above embodiment, and the conductors of the coil pattern overlapping in the laminating direction are produced so as to overlap vertically as shown in the sectional view of FIG. A total of 11 sheets were alternately stacked to form a ceramic green sheet laminate. This laminate was pressed and sintered as described above to obtain a ceramic coil.
[0059]
The evaluation results are shown in Table 1 as “Invention (staggered arrangement)”, “Invention (staggered arrangement + counter)”, and “Comparative Example”.
[0060]
[Table 1]

[0061]
As shown in Table 1, the amount of deformation of the ceramic coil of the present invention (staggered arrangement) is remarkably reduced to 以下 or less as compared with the comparative example. In the case where the counter was further provided, although the thickness was increased, the deformation was further reduced.
[0062]
Further, when the section observation magnification was 500 times with a tool microscope, no structural result such as delamination or crack was observed in the ceramic coil of the present invention, but delamination or crack occurred in the comparative example. Further, in the case of the comparative example, the ceramic coils were formed so as to be shifted in a V-shape in the laminating direction.
[0063]
Although the present invention has been described based on the example in which the ceramic coil of the present invention is applied to the stator of the permanent magnet motor, the present invention can be applied to a coil component having a spiral coil other than the field coil, such as an inductor. It will be obvious.
[0064]
【The invention's effect】
INDUSTRIAL APPLICABILITY The ceramic coil of the present invention has no cracks or delaminations and is a sound material in which crushing and distortion of a conductor pattern are reduced, so that it can be applied to applications in which a load or vibration is applied like a motor.
[Brief description of the drawings]
FIG. 1 is a plan view of a permanent magnet motor using a ceramic coil of the present invention.
FIG. 2 is a sectional view showing a state in which a permanent magnet motor using the ceramic coil of the present invention is mounted on a printed circuit board.
FIG. 3 is an external perspective view of a stator (ceramic coil) used in a permanent magnet motor.
FIG. 4 is a connection diagram showing connection of field coils in a stator (ceramic coil) according to one embodiment of the present invention.
FIG. 5 is an exploded perspective view of the stator (ceramic coil) shown in FIG.
FIG. 6 is a perspective view of a first conductor pattern on a back surface of the stator.
FIG. 7 is a plan view of a ceramic green sheet on which a coil pattern is formed by printing.
FIG. 8 is a plan view of a second ceramic green sheet on which a coil pattern is formed by printing.
FIG. 9 is a plan view showing a positional relationship between coil patterns.
FIG. 10 is a cross-sectional view of a coil sheet laminate.
FIG. 11 is a cross-sectional view of a ceramic coil (eg, a stator) according to the present invention after sintering.
FIG. 12 is a plan view of a ceramic green sheet provided with a ceramic portion (counter).
FIG. 13 is a sectional view of a coil sheet laminate provided with a ceramic portion (counter).
FIG. 14 is a cross-sectional view of a comparative example in which ceramic green sheets are laminated.
FIG. 15 is a sectional view of a ceramic coil of a comparative example after sintering.
FIG. 16 is a cross-sectional view showing an arrangement relationship of a coil pattern in a ceramic coil according to one embodiment of the present invention.
[Explanation of symbols]
10 Stator (ceramic coil)
15 Solder
19 opening
20 Ceramic green sheet for external terminals
30 Coil sheet laminate
40,50,40 ', 50', 60,80 Ceramic green sheet
22, 23, 24, 25 connection terminals
26 Second conductor pattern
42,52,42 ', 52', 62 Coil pattern
45 ceramic part (counter)
72, 73, 74 First conductor pattern
82 coil pattern
18 Bearing
90 permanent magnet rotor
91 permanent magnet
95 Rotation axis
100 permanent magnet motor
200 printed circuit board

Claims (3)

A plurality of coil patterns are printed and formed on one surface of the ceramic green sheet, and a plurality of the ceramic green sheets are stacked and sintered integrally to form a brushless motor ceramic coil.
The coil pattern is formed by winding a conductor line in a spiral shape with a predetermined line interval, and the conductor line of the coil pattern is provided at an overlapping position between conductor lines of another coil pattern which overlaps in the stacking direction and is adjacent. A ceramic coil for a brushless motor. The ceramic coil for a brushless motor according to claim 1, wherein a coil pattern is provided on one surface of the ceramic green sheet in a rotationally symmetric manner. The ceramic green sheet, wherein a plurality of ceramic green sheets each having a ceramic paste printed on a portion where the coil pattern is not formed are laminated and integrally sintered on one surface of the ceramic green sheet on which the coil pattern is formed by printing. 3. The ceramic coil for a brushless motor according to any one of 2.

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