JPH0155592B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hollow insulated metal wiring board.

In recent years, for circuit boards, a glassy glaze is coated on the surface of a metal core such as a steel plate, and this is fired to form an enamel layer on the surface of the metal core, and this enamel layer is used as an insulating layer. The enamel insulated metal wiring board (hereinafter simply referred to as the enamel board) has a conductive pattern formed on it.
It is attracting attention because of its excellent heat dissipation effect and mechanical strength.

In particular, enamel boards with steel cores,
Since the core is made of a magnetic material, it is more effective when used in motors, etc. In view of this, for example,
A technique such as that disclosed in the above publication has been proposed.

By the way, when fixing such a hollow substrate to an object to be attached such as a motor, conventionally there have been problems as described below.

Here, in FIG. 1, enamel insulating layers 2, 2 are uniformly formed on both the front and back surfaces of the metal core 1, as shown in FIG. 2, and on the surface of the upper enamel insulating layer 2, A conductor pattern 4 forming a circuit such as a motor speed control circuit is formed.

Now, the enamel board 5 shown in FIG. A plurality of claw pieces 7a of the stator case 7 arranged at intervals
By bending it inward and biting it into the hollow base plate 5, it is caulked and fixed to the stator case 7.

Now, the part of the enamel insulating layer 2 that is pressed down by the claw piece 7a is referred to as the fixed part of the enamel substrate 5, and this fixed part is the part of the enamel insulating layer 2 that is pressed by the claw piece 7a.
When crimped, since the enamel insulating layer 2 is glassy, a crack as shown by symbol C occurs in this layer.
When it advances to the corresponding part of the conductor pattern 4, the insulation between it and the metal core 1 may be broken, or
Alternatively, the conductor pattern itself may break, which poses a serious problem in practice.

In view of the above-mentioned points, the present invention has been devised to provide a hollow insulating layer which prevents the crack from propagating to the corresponding part of the conductor pattern when a crack occurs in the enameled insulating layer starting from the part to be fixed when the enameled board is fixed. The purpose is to provide an insulated metal wiring board.

Embodiments of the present invention will be described below with reference to FIG. 3 and subsequent figures.

FIG. 3 shows a cross-sectional configuration of a small motor equipped with an enamel substrate according to an embodiment of the present invention. The stator case 7 of the motor 6 is made by forming a magnetic material such as an iron plate into a cup shape. A stator magnet 11 made of an annular permanent magnet is fitted onto the inner peripheral surface of the stator case 7.

The bearing holding portion 7b formed in the center of the stator case 7 has an oil-impregnated metal 12 containing lubricating oil.
The oil-impregnated metal 12 rotatably supports the output shaft portion 13a of the rotating shaft 13. The rotating shaft 13 has a rotor core 14 having a plurality of salient poles.
is fitted onto the rotor core 14, and a coil 15 is further wound around the rotor core 14.

Further, a commutator 16 is fitted onto the rotating shaft 13, and each winding end of the coil 15 is connected to the commutator 16. The upper opening of the stator case 7 has a hollow substrate 17 according to the present invention.
is inserted, and this hollow base plate 17 is engaged with an engaging stepped portion 7c provided at the back of the opening end of the stator case 7.

On the other hand, in the center of the hollow substrate 17,
A bearing holder 18 formed in a cup shape is press-fitted, and an oil-impregnated metal 19 stored in this bearing holder 18 is attached to the other shaft end 13b of the rotating shaft 13.
is rotatably supported. A seat plate 21 mounted in the bearing holder 18 is adapted to come into contact with the shaft end 13b of the rotating shaft 13.
is adapted to receive the thrust force of the rotating shaft 13. In addition, what is designated by the reference numeral 22 is a brush whose base end is attached to the hollow substrate 17 and connected to the circuit of this substrate.

The enamel substrate 17 is formed by forming a enamel insulating layer 17b on both the front and back surfaces of a substantially disk-shaped metal core 17a made of a magnetic material such as a steel plate, and on the upper enamel insulating layer 17b, as shown in FIG. , a conductor pattern 17 made of silver or copper paste
It is shaped like c. The enamel insulating layer 17b is formed to have a thickness of about 50 to 200 μm by applying a glassy glaze to the surface of the metal core 17a and firing it. Further, the conductor pattern 17c is configured as a control circuit that controls the rotational speed of the motor 6 using a semiconductor such as a film resistor, a capacitor, or an integrated circuit.

As shown in FIG. 6, the enamel board 17 has a terminal piece 17d protruding from a part of the outer periphery, and the outer periphery end face excluding the terminal piece 17d is arranged so that the metal core 17a is exposed. After the enamel insulating layer 17b is formed, its outer peripheral end surface is punched out using a press or the like, and the exposed outer peripheral end surface of the metal core 17a and the inner peripheral surface of the opening of the stator case 7 are brought into contact with each other. By doing so, both are set at the same potential (earth), thereby preventing the generation of electrical noise.

Here, the features of the enamel board of the present invention are as shown in FIGS. 4 and 5, the enamel board 17 has a fixed part 17f which is a part to be fixed to the stator case 7, and a conductor pattern 17c. The reason is that a step as shown by the reference numeral 17g is provided on the surface portion of the metal core 17a located between the two.

That is, similar to the example shown in FIG. 1, the enamel board 17 is crimped and fixed at multiple locations by locally applying pressure using a crimping punch or the like so that the claw pieces 7a dig into the metal core 17a. A fixed part 17f is formed, and this fixed part 17
On the f side, a step 17g is provided in advance so that the thickness of the metal core 17a itself becomes thinner, and this step 17g allows the metal core 1 to be separated from the fixed portion 17f.
The hollow insulating layer 17b reaching the surface of 7a is bent. As shown in Fig. 6, these steps may be provided at multiple intervals in the circumferential direction, or they may be provided all around the circumference as shown in Fig. 7. It's okay.

Therefore, such a step of 17 g is replaced by a metal core 17.
By providing the crack C in a itself, when a crack occurs in the enamel insulating layer 17b from the fixed part 17f toward the right in FIG. 4 during fixation by caulking, as shown in FIG.
Since the hollow insulating layer 17b is bent at the step 9g, it turns 90 degrees and progresses upward, so the crack stops progressing at this part and does not reach the lower part of the conductor pattern 17c. do not have.

Note that the height h of this step 17g should be equal to or greater than the thickness of the enamel insulating layer 17b, and the length l of the lower step should be about the thickness of the enamel substrate 17 to achieve the intended purpose. This has also been confirmed experimentally. Note that in FIGS. 5 and 6, the reference numeral 17h is a through hole provided in the hollow substrate 17, and the hollow insulating layer 17b is formed even inside this hole.

8 to 10 show different embodiments, and the embodiment shown in FIG.
In the embodiment shown in FIG. 9, the cross section of the metal core 17a is bent into a crank shape to provide a step 17g, and in the embodiment shown in FIG. In the example, a fixed part 17f is provided in the center of the hollow substrate 17,
Fixing members 23 such as eyelets, rivets, or screws
Accordingly, the enamel substrate 17 is fixed to the object to be attached 24, and in either embodiment, it is possible to prevent cracks occurring in the enamel insulating layer from reaching the conductor pattern.

In all of the above embodiments, regarding the fixed portion 17f, a step 1 is formed in advance on the metal core 17a.
7g is provided, and then a hollow insulating layer is formed on the metal core. In addition, in the other embodiments shown in FIG. 7 and after, the same reference numerals as in the first embodiment are used for convenience in order to avoid complication of explanation.

As described above, according to the present invention, the enameled insulating layer made of glass is bent by the step provided in advance on the metal core itself of the enameled insulated metal wiring board, so that when the fixed part is fixed to the board, local pressure is applied. When a crack occurs in the fixed part of the enamel insulating layer due to the addition of a Therefore, there is no risk that the insulation between the conductor pattern and the metal core will be broken, and there is no risk that the conductor pattern itself will break.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional enamel insulated metal wiring board attached to a stator case of a motor, Fig. 2 is a sectional view showing a part of the same wiring board, and Fig. 3 is an enamel insulating metal wiring board according to an embodiment of the present invention. 4 is a sectional view of a motor equipped with a metal wiring board; FIG. 4 is a sectional view showing a part of the above wiring board; FIG. 5 is a sectional view showing the same wiring board installed in the stator case of the motor; FIG. 7 is a perspective view of another embodiment of the enamel insulated metal wiring board, and FIGS. 8 to 10 are sectional views showing other embodiments of the enamel insulated metal wiring board. . 7... Stator case of a motor as an object to be attached, 17a... Metal core, 17b... Enameled insulating layer, 17c... Conductor pattern, 17f... Fixed part, 17g... Step.

Claims (1)

[Claims] 1. A enamel insulated metal wiring board that is fixed to a pair to be attached and has an enamel insulating layer formed on the surface of a metal core, and a conductor pattern forming a circuit on this enamel insulating layer, A step is provided in advance on the surface of the metal core itself, which is located between the fixed part of the enamel insulated metal wiring board fixed to the mounted body and the conductor pattern, and this step allows the fixed part to be fixed to the fixed part. A enamel insulating metal wiring board, characterized in that the enamel insulating layer from the enamel to the surface of the metal core is bent.