JP2010051046A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and thin spindle motor which rotates a storage medium such as a disk or the like which is equipped with a reliable earth connector. <P>SOLUTION: A plate 1 includes a zinc-plated steel plate, and a flexible board 4 where an earth pattern is formed, is fixed onto the plate 1 by adhesion or the like. The plate 1 has a several μm of plated layer 2. At a protrusion 6 which is formed by being half-pressed, ground metal exposed by peeling the plated layer 2 from its flank, and a land section 3 formed semicircularly for an earth pattern, are connected with each other by solder 5, to form an earth section 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spindle motor for rotationally driving a recording medium such as a disc in the optical media field such as a CD-ROM (R), a DVD-ROM (R), a DVD-RAM, and more particularly to a ground connection structure of a substrate. is there.

  A spindle motor is used in a rotational drive device for a circular recording medium used in a CD-ROM (R), DVD-ROM (R), DVD-RAM disk or the like. As the spindle motor, a DC brushless motor is often used, and includes a turntable for mounting a recording medium and a drive unit that rotationally drives the turntable.

  The spindle motor described above is held on the rotor frame, a rotor frame having a rotor magnet that is multipolarly magnetized in the circumferential direction attached to the inner periphery, a rotating shaft fixed to the center of the rotor frame, and the rotor frame. A rotor composed of a turntable, a bearing that rotatably supports the rotating shaft, a bearing housing that holds the bearing, a stator base that holds the bearing housing and serves as an attachment portion to a motor set, There is known a configuration comprising a stator core disposed facing the rotor magnet and wound with a stator coil, and a substrate on which the end of the stator coil and leads of the position detection element are electrically connected. The stator base is generally composed of a metal plate, and the substrate is generally fixed on the plate by adhesion or the like.

  By the way, when the spindle motor is incorporated in the rotary drive device, it is necessary to make the electric potential of the plate serving as the mounting portion of the motor on the substrate and the set equal to the chassis potential of the set. This is because noise occurs when the potentials are different. Therefore, as a countermeasure against this noise, the copper foil land of the board and the plate are made conductive by screwing, and the potential between the set side and the motor is set by grounding the plate by connecting it electrically to the chassis on the set side. It was equipotential.

  However, motors are required to be thinner as the set becomes smaller and thinner. For this reason, it is necessary to reduce the thickness of the plate, which is the mounting portion of the motor. In this case, when screws are used, there is a problem that the hooking of the screws becomes small and the grounding cannot be stably taken. Moreover, the structure which forms earth | ground with a smaller area is needed for size reduction.

  In order to solve such problems, for example, as a method of conducting without using screws, a metal pin is press-fitted into a hole formed in the board, and then the metal pin and the land portion of the ground pattern are soldered to establish conduction. A structure has been proposed. (See Patent Document 1).

  FIG. 3 shows a cross-sectional view of the ground connection structure described in Patent Document 1. In FIG. 3, reference numeral 35 denotes a substrate made of a conductive material such as iron. An insulating layer 34 is laminated on the substrate 35, and a ground portion 33 is formed on the insulating layer 34, and a hole 36 is formed in the substrate 35, and a prismatic metal is formed in the hole 36. The pins 31 are press-fitted and fixed, and the metal pins 31 and the land portions 33 of the ground pattern are connected by solder 32 to constitute a ground connection mechanism for the substrate.

Further, there is a structure in which a protrusion is formed on a metal plate, a through hole is provided in a printed board, the protrusion is inserted into the through hole, and conduction is achieved by soldering. (See Patent Document 2)
FIG. 4 shows a cross-sectional view of the ground connection structure described in Patent Document 2. In FIG. 4, the protrusions 42a formed on the metal plate 42 are inserted into the through holes 41b formed on the printed circuit board 41 bonded to the metal plate 42 with an adhesive (such as a double-sided tape) 43. The board 41 and the metal plate 42 are formed by connecting a protruding portion 42a protruding to the conductor 41a side of the printed board 41 and the ground conductor 41a with solder 44, and connecting the metal plate 42 and the ground conductor 41a of the printed board 41 Are electrically connected.
Japanese Utility Model Publication No. 5-76072 Japanese Unexamined Patent Publication No. 63-204794

  However, in the conventional configuration described in Patent Document 1, it is necessary to press-fit a pin, and there is a problem that man-hours are required. Also, in order to firmly fix the pin to the substrate and to ensure electrical continuity, it is necessary to have a configuration in which the pin is passed through the substrate and solder is placed in the gap between the pin and the substrate. There was a problem of becoming.

  Moreover, in the structure described in the said patent document 2, even if it piled up solder, it was unable to confirm whether the solder was surely joined, and there existed a subject that long-term reliability could not be guaranteed.

  An object of the present invention is to solve such a conventional problem, and to provide a spindle motor having a ground joint structure with a low cost, a small number of steps, and a reduced height and area.

  In order to solve the above-mentioned problems, the present invention forms a projection on a plate made of a plated steel plate by half-pressing with a die while forming a hole in the ground pattern of the substrate. A land portion having an asymmetrical shape with respect to the center is formed around the hole portion, the protrusion portion is inserted into the hole portion, and the protrusion side surface and the land portion of the ground pattern are connected to the protrusion portion. It is a brushless motor provided with the earth connection structure formed by soldering connection in the state where a part of side surface is exposed.

  According to the first aspect of the present invention, the plating layer of the projection of the plate is peeled off by half pressing to expose the bare metal, and the soldering connection is performed at the land portion of the ground pattern of the substrate. Since the portion is configured, it is possible to easily connect to the ground without using a member such as a screw. Moreover, since only the height of the solder piled up on the land portion defines the overall height of the ground connection portion, the thickness can be reduced. In addition, the shape of the land portion of the substrate is formed in an asymmetrical shape with respect to the center of the hole in the land portion, and soldered connection is performed with a part of the side surface of the protruding portion exposed, thereby connecting the solder Therefore, it is possible to provide a brushless motor having a highly reliable ground joint structure.

  According to the invention described in claim 2, in the motor described above, by forming the land portion into a half-moon shape, the flow of solder is uniform in at least the circular portion of the land portion. It can be carried out.

  According to the invention described in claim 3, in the motor described above, a part of the outer periphery of the protruding portion is exposed from the solder while securing the solder joint strength by covering the solder with more than half of the land portion. Thus, it is possible to easily check the solder bonding state, and it is possible to provide a brushless motor having a highly reliable ground bonding structure.

According to the invention described in claim 4, by making the plate a galvanized steel sheet that has been subjected to a thin organic film treatment, an improvement in rust prevention effect and soldering workability can be realized simultaneously, and the fastening strength of solder is increased. be able to. Further, by improving the wettability of the solder, the solder height can be lowered, and a brushless motor having a ground connection structure suitable for thinning can be provided.

  According to the fifth aspect of the present invention, a DVD-ROM having a small area, a low height, and a highly reliable ground connection structure, which can stably take measures against noise, and can be reduced in size and thickness. A spindle motor for rotationally driving a recording medium such as the above can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a longitudinal sectional view of a disk drive spindle motor according to an embodiment of the present invention. As shown in FIG. 1, the spindle motor for driving the disk that rotates the disk 24 is constituted by a brushless motor having an outer diameter of about 10 mm. This disk drive spindle motor includes a stator 18 and a rotor 17 that rotates integrally with a rotary shaft 19.

  The stator 18 is a substantially cylindrical bearing 7 that rotatably holds the rotary shaft 19, a housing 8 that is erected on the plate 1 in a state where the bearing 7 is press-fitted inside, and is externally fitted to the housing 8. The stator core 9 is composed of a winding assembly 11 including a stator coil 10, and the end of the stator coil 10 is soldered and electrically connected to a flexible substrate 4 attached on the plate 1. .

A disc-shaped thrust plate 21 is disposed in the hole formed in the plate 1 to rotatably support the rotary shaft 19 in contact with the thrust direction from the base end side. Is attached to the lower surface of the plate 1.
A retaining member 23 that prevents the rotating shaft 19 from coming off the bearing 7 of the stator 18 is fixed in the vicinity of the thrust plate 21 of the rotating shaft 19.

  The rotor 17 includes a rotor frame 13 attached to the tip end of the rotary shaft 19, an annular and rectangular clamping magnet 14 attached to the rotor frame 13, and a disk mounting that is an upper surface portion of the clamping magnet 14. The disk 24 is mounted and attached to the inner part of the rotor frame 13 so as to face the stator core 9 and the anti-slip material 15 made of rubber having a friction coefficient larger than that of the clamp magnet 14. The drive magnet 16 is formed.

  The ground connection structure, which is a feature of the present embodiment, will be described below.

  FIG. 2 shows a ground connection structure according to the first embodiment of the present invention. 2A is a plan view of the ground connection structure according to the first embodiment of the present invention, and FIG. 2B is a longitudinal sectional view of the ground connection structure according to the first embodiment of the present invention. In FIG. 2B, the plate 1 is made of a galvanized steel plate, and a flexible substrate 4 on which a ground pattern is formed is fixed on the plate 1 by adhesion or the like. A hole 12 is formed in the ground pattern, and a land portion 3 having an asymmetric shape with respect to the center of the hole 12 of the ground pattern is formed around the hole 12 of the ground pattern. Further, the plate 1 is formed with a protrusion 6 by being half-pressed by pressing and protruding to a height of 100 μm. Although the plating layer 2 of several μm is formed on the surface of the plate 1, the protruding portion 6 is formed by pressing halfway by pressing, so that the plating layer 2 on the outer peripheral portion of the protruding portion 6 is peeled off and the base metal Is exposed. As a result, the bare metal part appearing from the side surface of the protrusion 6 and the land part 3 of the ground pattern can be electrically connected by the solder 5.

  Thus, the ground portion 20 is formed. As shown in FIG. 2A, the land portion 3 of the ground pattern has a length a from the center of the land portion 3 to the string that is larger than the radius of the land portion 3 and larger than the radius r of the protrusion 6. It is formed in a small meniscus shape and is configured such that a part of the outer periphery of the protrusion 6 is exposed from the solder 5. With this configuration, the solder 5 is covered so that it covers more than half of the land portion 3 and the strength of the solder joint is secured, as shown in FIG. Therefore, a highly reliable ground part can be configured.

  In the present embodiment, the land portion 3 has a half-moon shape, but the shape is not limited to this as long as a part of the outer periphery of the projection portion 6 is exposed from the solder 5. That is, if the land portion 3 is formed around the hole portion 12 of the ground pattern in an asymmetrical shape with respect to the center of the hole portion 12, a part of the side surface of the projection portion 6 is exposed. Soldering connection is possible, and the joining state of solder can be confirmed.

  However, since the height of the protrusion 6 can protrude only about 100 μm in order to reduce the thickness of the motor, the solder 5 is not only the side surface of the protrusion 6 but also the upper plating layer as shown in FIG. The surface covered with 2 must be covered. The surface of the galvanized steel sheet, which is the material of the plate 1, is further subjected to surface treatment for improving fingerprint resistance, good conductivity, paintability, slidability, etc., on the surface of the plated layer formed for rust prevention. ing. Depending on the surface treatment, as shown in FIG. 2C, the solder does not conform to the surface covered with the plating layer 2 on the upper side of the protrusion 6, and there is no gap between the surface and the plating layer 2 on the upper side of the protrusion 6. The so-called tempura solder state is likely to occur. In order to prevent this, the surface treatment of the material of the plate 1 is made as thin a thin film as possible (film thickness is 3 μm or less, preferably 1.5 μm to 2 μm), thereby improving the wettability of the solder. Since the familiarity of the solder on the upper surface of the protrusion is improved, the solder workability is stabilized and the fastening strength of the solder can be increased.

  The resin for forming the organic film must be a resin that melts and softens within 3 to 5 seconds at the soldering temperature. In this case, since the wettability of the solder is improved, the height of the solder can be reduced and a ground structure having a low height can be provided. Specifically, the solder height dimension could be 0.5 mm or less.

  As a thin organic film treated product, for example, Nippon Steel's gin coat 21 (registered trademark) QS material is available. The QS material of ZINCOAT 21 (registered trademark) is excellent in corrosion resistance even in a thin film, has a small resistance value of the coating layer, and has excellent weldability. Therefore, it is suitable for the configuration of this motor and provides a highly reliable motor. be able to. In addition, since it is a chromate-free film treatment, it is possible to avoid environmental load problems.

  The spindle motor configured as described above can be configured to be extremely small and thin while being provided with the ground portion 20, and can also provide a highly reliable motor.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various application developments are possible within the scope of the gist of the invention.

  The present invention provides a stable ground connection structure having a low height, thereby enabling stable noise countermeasures, and a spindle for rotationally driving a recording medium such as a DVD-ROM that can be reduced in size and thickness. Useful as a motor.

1 is a longitudinal sectional view of a disk drive device according to an embodiment of the present invention. (A) A plan view of the ground connection structure according to the embodiment of the present invention, (b) a longitudinal sectional view of the ground connection structure according to the embodiment of the present invention (c) a ground connection structure according to the embodiment of the present invention Vertical sectional view for explanation Longitudinal section of conventional earth connection structure Vertical section of another conventional earth connection structure

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plate 2 Plated layer 3, 33 Ground part of earth pattern 4 Flexible board 5, 32, 44 Solder 6, 42a Protrusion part 7 Bearing 8 Housing 9 Stator core 10 Stator coil 11 Winding assembly 12 Hole part of earth pattern 13 Rotor frame 14 Clamping magnet 15 Non-slip material 16 Drive magnet 17 Rotor 18 Stator 19 Rotating shaft 20 Ground part 21 Thrust plate 22 Thrust cover 23 Retaining member 24 Disc 31 Metal pin 34 Insulating layer 35 Substrate 36 Hole 41 Printed circuit board 41a Conductor 41b Through hole 42 Metal plate 43 Adhesive a Length from center of land to chord r Radius of protrusion

Claims (5)

A rotating shaft, a bearing that supports the rotating shaft, a bearing housing that holds the bearing, and a plate that is a mounting surface for a device that holds the bearing housing and mounts a motor made of a plated steel plate; A brushless motor comprising a substrate having a ground pattern formed on a layer and having a ground portion for electrically connecting the plate and the ground pattern of the substrate. Forming a hole in the ground pattern, forming a land part having an asymmetrical shape with respect to the center of the hole, around the hole, and inserting the protrusion into the hole, A brush having a ground connection structure in which a protrusion side surface and a land portion of the ground pattern are connected by soldering in a state where a part of the side surface of the protrusion is exposed. Sumota. 2. The brushless motor according to claim 1, wherein the land portion has a half-moon shape. The brushless according to any one of claims 1 to 2, wherein a length a from the center of the land portion to the string is larger than a radius of the land portion and smaller than a radius r of the protrusion portion. motor. The brushless motor according to any one of claims 1 to 3, wherein the plate is made of a galvanized steel sheet and is subjected to a thin film organic film treatment. The brushless motor according to any one of claims 1 to 4, wherein the brushless motor is used in a spindle motor for rotationally driving a recording medium such as a disk in a field of optical media such as a DVD.

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