JPH10336985A - Radiating device for driving circuit in brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a contact between a printed board and a metal plate by locating the plate so that it may overlap one face of the printed board, and cutting a part of the plate upward so that it may thermally conduct with an IC on the printed board at the other face of the printed board. SOLUTION: A printed board 12 and a plate 17 are pasted to each other with an adhesive. Other than using an adhesive, coining calking, screwing, or a combination of these methods would be used for joining the printed board 12 and the plate 17. The plate 17 has a hook-like section cut upward 18, which is in contact with a GND pattern 13 for IC formed on the printed board 12. The area of the GND pattern 13 is set larger than the one necessary for soldering for conduction between the cut section 18 and an IC 16, and the cut section 18 of the plate 17 is so located that it may be brought into contact with the GND pattern 13. By this method, a sure contact can be obtained between the printed board 12 and the plate 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiator for a drive circuit in a brushless motor.

[0002]

2. Description of the Related Art Heretofore, a radiating fin has been known as a radiating device of a drive circuit in a brushless motor. A heat radiating device can be realized by attaching metal radiating fins to the heat-generating electronic components by screws or the like. This method is possible with a relatively large motor such as a power motor, but a relatively small FDD motor or the like requires a thin shape, so that a radiation fin cannot be attached due to space limitations. There is also a problem that the number of parts increases.

Conventionally, as a heat radiating device for a drive circuit in a brushless motor, other than a heat radiating fin, Japanese Patent Application Laid-Open No.
No. 259,666 is known. 3 and 4 show the structure of a heat radiator of a drive circuit in a conventional brushless motor. In FIGS. 3 and 4, the printed circuit board 21 near the IC 20 is notched, and the metal plate 22 on the opposite side of the printed circuit board 21 is bent at the notched portion so that the height is equal to the soldering surface of the heat dissipation lead frame of the IC 20. And a heat dissipation lead frame is soldered to the plate to constitute a heat dissipation device of the drive circuit.

[0004]

In the above-mentioned conventional configuration,
When an error occurs between the soldering surface of the printed circuit board 21 and the height of the metal plate 22, or when one of the superimposed printed circuit board 21 and the metal plate 22 warps, the strength of the soldered portion is insufficient. There was a problem that.

An object of the present invention is to solve such a conventional problem and to ensure a contact state between a printed board and a metal plate.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a rotor unit comprising a shaft, a rotor frame rotating integrally with the shaft, and a main magnet fixed inside the outer periphery of the rotor frame. And a printed circuit board, a bearing, a wound stator core, and a stator unit including a plate to which the stator core is attached.The plate overlaps one surface of the printed circuit board, and a part of the plate includes a printed circuit board. This is a heat dissipation device for a drive circuit in a brushless motor provided with a cut-and-raised portion that is thermally conductive with an IC on a printed circuit board on the other surface.

This makes it possible to dissipate the heat generated by the IC of the drive circuit by the plate. Further, since the printed circuit board is sandwiched between the plate and the cut-and-raised portion from both sides, the contact state between the heat-generating portion and the heat-radiating portion can be ensured. it can.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be embodied in the form described in each claim. As described in claim 1, a shaft, a rotor frame rotating integrally with the shaft,
A rotor portion composed of a main magnet fixed to the inside of the outer periphery of the rotor frame, a printed circuit board, a bearing, a wound stator core, and a stator portion composed of a plate to which they are attached; The I on the printed circuit board overlaps with one surface of the printed circuit board and is partially provided on the other surface of the printed circuit board.
By providing a cut-and-raised portion that is thermally conductive with C,
The heat dissipation function is provided without increasing the number of parts, and the printed circuit board is sandwiched between the plate and the cut-and-raised portion from both sides, so that the contact between the heat-generating portion and the heat-radiating portion can be more reliably achieved.

In addition, the cut-and-raised portion is directly soldered to a GND pattern for an IC which is set to be larger than an area fixed on a printed circuit board of the IC, so that the number of parts is not increased. The heat generating part and the heat radiating part can be connected to each other.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. An example of an FDD motor, which is required to be thin and for which the present invention is particularly effective, will be described. According to the present invention, a relatively large power motor or the like can be reduced in size, and the present invention can be applied to brushless motors in general.

(Embodiment 1) In FIG. 1, for example, FDD
The configuration of a brushless motor such as a motor will be described. A shaft 1 that engages with a center hole of a disk hub that forms a center of a disk-type storage medium, a rotor frame 2 that rotates integrally with the shaft 1, and a hub magnet that is fixed to an outer surface of the rotor frame 2 and attracts the disk hub. 3, a leaf spring 4 of an elastic material fixed to the inner surface side of the rotor frame 2,
A rotor pin comprising a drive pin fixed to the leaf spring and protruding to the outer surface side of the rotor frame through a hole of the rotor frame; and a main magnet fixed to an inner periphery of the rotor frame. Further, the printed circuit board 7, a plate 8 that overlaps with the back surface of the printed circuit board 7, a part of which is bent into a hook shape to be in contact with the surface of the printed circuit board 7, a bearing 9 fixed to the plate 8, and a coil The brushless motor is configured by including a stator unit including the stator core 10 formed as described above.

A drive circuit is formed on the printed circuit board 7, and the IC 11 in the circuit is important for controlling the number of rotations of the motor. While the motor is being driven, the IC 11 generates heat. However, the IC 11 is weak to heat and needs to radiate heat.

Therefore, in the present embodiment, in the brushless motor shown in FIG. 1, a heat radiating device of a drive circuit in the brushless motor is formed as shown in FIG. In FIG.
The heat dissipation device is an IC in which a GND terminal 15 is connected to a printed circuit board 12 and a GND pattern 13 thereon by soldering 14.
16 and a plate 17 overlapping the back surface of the printed circuit board 12. Printed circuit board 12 and plate 1
7 is bonded with an adhesive. In addition to the adhesive, the printed circuit board 12 and the plate 17 may be made by coining or screwing, or a combination thereof.
Can be joined. The plate 17 has a hook-shaped cut-and-raised portion 18 and a G for IC on the printed circuit board 12.
It is in contact with the ND pattern 13. Thus, the plate 17 plays a role not only as a reinforcing means of the original printed circuit board 12 but also as a radiator. The area of the GND pattern 13 for the IC on the printed circuit board 12 is
Printed circuit board 1 necessary for soldering for conduction with
2 is set to be larger than the area above, so that the cut-and-raised portion 18 of the plate 17 contacts this GND pattern. The hook-shaped cut-and-raised portion 18 of the plate 17 can be referred to as a hook heat sink. With the above configuration, a heat dissipation device can be realized without increasing the number of components. Furthermore, the cut-and-raised portion 18 of the plate 17 can be realized at low cost. In addition, since the front and back surfaces of the printed circuit board 12 are cut and raised so that the cutout portion 18 and the plate 17 are sandwiched therebetween, the contact state between the heat generating portion and the heat radiating portion can be ensured.

(Embodiment 2) In FIG. 2, a heat radiator is mounted on a printed circuit board 12 and a GND pattern 13 on the printed circuit board 12.
4 includes an IC 16 to which a GND terminal 15 is connected, and a plate 17 overlapping the back surface of the printed circuit board 12. The plate 17 has a hook-shaped cut-and-raised portion 18 and is in contact with the IC GND pattern 13 on the printed circuit board 12. By bonding the hook-shaped cut-and-raised portion 18 and the GND pattern 13 by solder 14, the IC 16 serving as a heat generating portion and the plate 17 serving as a heat radiating portion are joined.
Can be more reliably contacted, and the heat dissipation function can be enhanced. Also, by soldering, the plate 17
Plays a role of GND. However, since the plate 17 is used as the heat radiator, the GN of the plate 17 and the IC 16 is used.
No jumper or the like other than the GND pattern 13 is interposed between the D terminals 15. When there are two or more GND terminals 15 of the IC 16, there are two or more GND patterns 13.
At least one cut-and-raised portion 18 of the plate 17 is brought into contact. For this plate 17, for example, a tin-plated steel plate is used. With the above configuration, a heat dissipation device can be realized without increasing the number of components.

In the above description, the connection between the cut-and-raised portion 18 of the plate 17 and the GND pattern 13 for the IC on the printed circuit board 12 has been described by way of soldering. Connection, or a combination of a plurality of them, can be similarly implemented.

[0016]

As is apparent from the above description, claim 1
According to the invention described in (1), the plate is originally a reinforcing means for the printed circuit board, and a cut-and-raised portion is provided on the plate overlapping the back surface of the printed circuit board, and the plate is brought into contact with the GND pattern of the IC on the surface of the printed circuit board. An advantageous effect of playing a role of a heat radiating device and preventing malfunction of the IC due to high temperature can be obtained. Further, since the plate and the cut-and-raised portion of the plate sandwich the front and back surfaces of the printed circuit board, an advantageous effect that a contact state between the heat generating portion and the heat radiating portion can be ensured can be obtained.

According to the second aspect of the present invention, the cut-and-raised portion of the plate, which is a heat radiating device of the drive circuit in the brushless motor of the first aspect, and the GND pattern for the IC on the surface of the printed circuit board in contact with the plate. By soldering, there is obtained an advantageous effect that the contact state between the plate and the GND pattern for the IC is made more reliable, heat conduction is improved, and the IC does not malfunction due to high temperature. In particular, since the area of the GND pattern is set to be larger than the fixing area of the IC to the printed circuit board surface,
The heat dissipation of the IC is effective.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a brushless motor according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a heat radiating device of a drive circuit in the brushless motor according to the first embodiment of the present invention.

FIG. 3 is a side sectional view of a heat dissipation device of a drive circuit in a conventional brushless motor.

FIG. 4 is a top view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft 2 Rotor frame 7, 12 Printed circuit board 8, 17 Plate 9 Bearing 11, 16 IC 13 GND pattern 14 Solder 15 GND terminal 18 Cut-and-raised part

Claims (2)

[Claims] 1. A rotor comprising a shaft, a rotor frame rotating integrally with the shaft, a main magnet fixed inside the outer periphery of the rotor frame, a printed circuit board, a bearing, and a wound stator core. A stator part comprising a plate for attaching them, wherein the plate overlaps one surface of the printed circuit board, and a part of the plate is thermally conductive to an IC on the printed circuit board on the other surface of the printed circuit board. Radiator for drive circuit in brushless motor with raised part. 2. A heat radiation device for a drive circuit in a brushless motor according to claim 1, wherein the cut-and-raised portion is directly soldered to a GND pattern for the IC, which is set to be larger than an area fixed to the printed circuit board of the IC.