JP2006042572A - Multilayer ceramic coil and motor employing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer coil for high efficiency motor exhibiting heat resistance and impact resistance in which magnetism collection efficiency of winding is enhanced and motor output is enhanced while reducing loss. <P>SOLUTION: A plurality of ceramic substrates 51 printed with a coil pattern 53 are laid in layers through conductive paste, the coil patterns 53 of respective layers are connected electrically by through holes to form the coils of a plurality of phases as one multilayer structure wherein a powdery magnetic material 52 is admixed with the ceramic substrate in the center of individual coil patterns 53. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multilayer ceramic coil used for an axial gap type brushless motor used for rotationally driving a recording disk such as a magnetic or optical disk.

  Conventionally, as shown in FIG. 4, the brushless motor generally has a plurality of coils 34 soldered and fixed to a printed circuit board 36, and a magnet 35 is fixed to the rotor frame 32 so as to face the coils 34 with a gap.

In this type of brushless motor, a coil is formed by winding using a wire. Recently, the coil is formed as a printing pattern on a film 40 such as an epoxy resin, a polyester resin, or a polyimide resin by improving the printed wiring technology. A method is known in which a coil sheet 44 is formed by applying a coil conductor pattern, and a coil is formed by laminating a large number of such coil sheets 44 as shown in FIG. (For example, see Patent Documents 1, 2, 3, and 4.)
Such a laminated coil does not require a metal wire to be wound around a core as in the prior art, and is advantageous for obtaining a small motor having a high winding density.

  However, since such a conventional laminated coil needs to laminate a plurality of coil sheets 44 using an adhesive, a process of forming a uniform adhesive layer on each sheet surface and bonding them is necessary. Therefore, there is a problem that the cost of the laminated coil increases. In addition, since the coil sheet uses plastic or composite material, its heat resistance is low, and the operation as a motor becomes unstable under the influence of heat generated by copper loss, iron loss or environmental temperature. Conditions are also limited.

For this reason, a conductor pattern for a coil is formed on a green sheet obtained from a ceramic powder by a screen printing technique, a photolithography technique, a plating technique, etc. to solve the problem of such a conventional laminated coil. There has been proposed a laminated coil constructed by laminating a plurality of green sheets each having the shape of, and firing them as a unit. (For example, see Patent Document 5)
JP-A-57-68565 JP-A-57-186940 JP-A-57-68656 JP 58-33958 A JP-A-64-59902

  When a laminated coil using a conventional coil sheet made of plastic, etc. or a green sheet made of ceramic is used for a motor, the torque is reduced at the same volume compared to the conventional one using a stator core because it becomes a coreless type. There was a point.

  In order to solve the above-described problems, the present invention is a method of laminating a ceramic base material on which a plurality of coil patterns are printed with a conductive paste, and electrically connecting the coil patterns of the respective layers through through holes to form a plurality of phases. These coils are formed as a single laminated structure, and a powdery magnetic material is mixed with the ceramic base material at the center of each coil.

  Further, the present invention is characterized in that the powdery magnetic material is magnetically coated with an insulating coating.

  According to the multilayer ceramic coil of the present invention, a ceramic base material on which a plurality of coil patterns are printed with a conductive paste is laminated, and the coil patterns of the respective layers are electrically connected through through holes to form a plurality of phases. The coil is formed as a single layered structure, and the magnetic material in the center of each coil pattern is mixed with a powdered magnetic material. Without increasing the number of points, it is possible to obtain a motor having a higher torque than the conventional coreless type.

  Moreover, it is possible to reduce the loss caused by the eddy current generated in the magnetic material by using the magnetic powder that is insulatively coated on the powdered magnetic material.

  Therefore, it is possible to provide a high-efficiency motor with high torque and low loss.

  A ceramic base material on which a plurality of coil patterns are printed with a conductive paste is laminated, and the coil patterns of the respective layers are electrically connected through through holes to form a multi-phase coil as one laminated structure. Then, a powdery magnetic material is mixed with a ceramic base material at the center of each of the coil patterns, and a magnetic powder that is insulation-coated on the powdery magnetic material is used.

  A motor according to the present invention is shown in FIGS. FIG. 1 is a sectional view thereof. In the figure, reference numeral 1 denotes a rotating shaft, which is fixed vertically to the rotor frame 2. Reference numeral 4 denotes a laminated ceramic coil, which is fastened to the bearing 3 by a housing. The rotating shaft 1 is rotatably inserted into the bearing 3. A magnet 5 is fixed to the rotor frame 2 so as to face the laminated ceramic coil 4 with a gap. An exciting current is supplied to the multilayer ceramic coil 4, and the motor is rotated by the attractive / repulsive force with the magnet 5.

  2A is a development view showing the configuration of the multilayer ceramic coil, FIG. 2B is a cross-sectional view of the multilayer ceramic coil, and FIG. 2C is an external view of the multilayer ceramic coil. The coil patterns 4a and 4b are printed on the ceramic substrate 4c, and the coil patterns 4a and 4b are alternately electrically connected by the through holes 4d. The coil patterns 4a and 4b of each phase are electrically connected by the crossover pattern 4e. The terminal of each phase is electrically connected to the electrode 4g by the terminal pattern 4f. For example, the electrodes 4g are concentrated on the four corners or one side of the multilayer ceramic coil 4. The multilayer ceramic coil 4 is soldered and fixed to the printed circuit board 6 by the electrode 4g.

  FIG. 3 is an exploded perspective view of the multilayer ceramic coil. Magnetic powder 52 is mixed at the center of the coil conductor pattern 53 of the ceramic substrate 51 on which the coil conductor pattern 53 made of a conductive paste is printed to form a single laminated structure.

  According to the present embodiment, a magnetism collecting effect in the motor winding portion can be obtained, and it can be used as a coil for a motor with high torque, low loss and high efficiency.

In this embodiment, it is possible to reduce the loss of eddy current generated in the magnetic powder 52 by using the magnetic powder 52 in FIG. The mixing density of the magnetic powder 52 can be increased, and a magnetic flux collecting effect can be obtained.

  The multilayer ceramic coil of the present invention is most suitable for miniaturization and high efficiency of a motor, and is useful for a space saving application, for example, a spindle motor of a disk medium used for a portable device or the like.

Sectional view of a motor according to the present invention (A) Pattern front view of multilayer ceramic coil according to the present invention (b) Cross-sectional view of multilayer ceramic coil according to the present invention (c) Outline drawing of multilayer ceramic coil according to the present invention 1 is an exploded perspective view of a multilayer ceramic coil according to the present invention. Cross section of conventional motor Exploded perspective view of conventional laminated coil for motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2, 32 Rotor frame 3 Bearing 4 Multilayer ceramic coil 4a, 4b Coil pattern 4c, 51 Ceramic base material 4d Through hole 4e Crossover pattern 4f Terminal pattern 4g Electrode 5, 35 Magnet 6, 36 Printed board 34 Winding coil 40 Film 42, 53 Coil conductor pattern 44 Coil sheet 52 Magnetic powder

Claims (3)

A ceramic base material on which a plurality of coil patterns are printed with a conductive paste is laminated, and the coil patterns of the respective layers are electrically connected through through holes to form a multi-phase coil as a single laminated structure. A laminated ceramic coil, wherein a powdery magnetic material is mixed with a ceramic base material at the center of each coil pattern. 2. The multilayer ceramic coil according to claim 1, wherein the powdered magnetic material is magnetically coated with an insulating coating. A motor using the multilayer ceramic coil according to claim 1.