JPH07105609B2 - Circuit device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a circuit device provided with noise countermeasures.

[Prior Art] As shown in FIG. 6, a T-type LC filter has two inductance elements L1 and L2 connected in series to a signal transmission line.
And a capacitor C1 connected between these midpoints and ground. The inductance elements L1 and L2 of this LC filter have already been constructed by inserting conductor wires into ferrite beads.

[Problems to be Solved by the Invention] By the way, when there are many signal transmission lines like a computer circuit and it is necessary to connect a T-type LC filter to each signal transmission line, As many as twice as many ferrite beads are required, which makes the filter assembly troublesome. Further, it is difficult to make ferrite beads extremely compact with mass productivity, and there is a limit to the miniaturization of the T-type LC filter. Further, as the ferrite beads are downsized, the volume of ferrite decreases, and it becomes impossible to obtain a sufficient noise absorbing effect.

Therefore, an object of the present invention is to provide a circuit device in which a large number of filters having an excellent noise absorption effect can be easily configured.

[Means for Solving Problems] The present invention for solving the above problems and achieving the above objects will be described with reference to the reference numerals of FIGS. 1 to 5 showing an embodiment. 1 and a circuit component 2 arranged on the substrate 1, and a connector 3 for connecting an electric circuit including the circuit component 2 to an external circuit, and the connector 3 is a plurality of parts derived from a connector body 5. In the circuit device having the lead 7 of the above, and the lead 7 is electrically connected to the substrate 1, a plurality of leads corresponding to the lead 7 are provided between the main body portion 5 of the connector 3 and the substrate 1. Through hole
One or a plurality of magnetic substance blocks 11 and 14 having 15 and a plurality of individual electrodes 18 and a ground electrode having a plurality of through holes 17 corresponding to the leads 7 and for obtaining a plurality of capacitors.
At least one or a plurality of dielectric substrates 12 provided with 19 are arranged, and the leads 7 are connected to the magnetic block 1.
The individual electrodes 18 are connected to the leads 7 through the through holes 15 of 1 and 12 and the through holes 17 of the dielectric substrate 12, and the ground electrode 19 is connected to the ground conductor 21 of the circuit board 1 by a conductor member. The present invention relates to a circuit device characterized by the above.

[Operation] In the above invention, the magnetic body block 11 surrounding the lead 7,
14 functions as a magnetic core of the inductance element, and leads 7
An inductance element is formed by a combination of the magnetic blocks 11 and 14 with each other, and a noise and / or a radiation noise conducted through the lead 7 is suppressed by a combination of the inductance element and a capacitor. Further, the magnetic body blocks 11 and 14 also function as absorbers of electromagnetic wave noise, and suppress noise radiated from the lead 7 to the outside, noise entering the lead 7 from the outside, and electromagnetic wave interference between the leads 7.

[Embodiment] Next, an electronic circuit device according to an embodiment of the present invention will be described with reference to FIGS. In this electronic circuit device, a plurality of circuit components 2 are mounted on an insulating circuit board 1, and a connector 3 for connecting an electric circuit including the circuit components 2 to an external electronic circuit device is provided. It is configured by mounting the LC filter assembly 4.

The connector 3 includes a main body 5 made of an insulating material, a large number of joints 6 held by the main body 5, and the joints 6.
7 leads (20 in this example) derived from
Consists of. Each lead 7 has a portion 7a led out in parallel with the substrate 1 and a portion 7b extending perpendicularly to the substrate 1, and is inserted into the through hole 8 of the substrate 1 and provided with the connection conductor 9 provided on the substrate 1. It is fixed with solder 10 on. The pitch of the leads 7 is 2 mm, and the diameter of the leads 7 is 0.9 mm.

The filter assembly 4 includes a first magnetic block 11, a capacitor block including a dielectric substrate 12, a ground plate 13,
And a second magnetic block 14.

The first and second magnetic blocks 11 and 14 are composed of ferrite cores, and a large number (in this example, corresponding to the arrangement of the leads 7).
20) through holes 15 and 16 respectively. The first and second magnetic blocks 11 and 14 are granulated by adding a binder to a Ni-Zn ferrite material, granulated by dry molding, and drilled according to the lead 7 of the connector 3 in consideration of shrinkage due to firing. The through holes 15 and 16 are formed and then fired,
It has a magnetic permeability of about 1000, and measures 45 mm long, 5 mm wide, and 3 mm thick.

The dielectric substrate 12 forming the capacitor block has a large number of through holes 17 corresponding to the leads 7, and further has one main surface 12
The a has a large number of individual electrodes 18 so as to surround the through hole 17, and the other main surface 12b has a common ground electrode 19. Individual electrode 1
8 are separated from each other as shown in FIG. 4 and arranged so as to be adjacent to the through hole 17. The ground electrode 19 is provided at a position slightly separated from the through hole 17 as shown in FIG. 5, and has a portion facing each individual electrode 18. This dielectric substrate 12
Is a green sheet with a thickness of about 1 mm made of SrTiO3 based material by wet molding, and after allowing for shrinkage, the through holes 17 are formed by punching in accordance with the pitch of the leads 7, and then fired. It is a porcelain dielectric substrate with a length of 50 mm, a width of 7 mm and a thickness of 0.85 mm. The dielectric constant of this dielectric substrate 12 is about 30,0.
00. The individual electrode 18 and the ground electrode 19 are dielectric substrates.
12 is formed by screen-printing Ag paste and firing. The capacitance of each capacitor corresponding to each lead 7 is about 1000 pF.

The ground plate 13 has a cutout groove 20 for inserting the lead 7, and a main surface portion 13a corresponding to the ground electrode 19 of the dielectric substrate 12.
Have. Further, the ground plate 13 has a pair of legs 13b and 13c for connecting to the ground wiring conductor 21 of the circuit board 1.

When assembling the filter assembly 4, the leads 7 of the connector 3 are inserted into the through holes 15 of the first magnetic body block 11, respectively. On the other hand, the one in which the ground plate 13 is soldered to the ground electrode 19 of the dielectric substrate 12 is prepared, and the individual electrode 18
Apply cream solder (not shown) to the. Then, each lead 7 is inserted into each through hole 17 of the dielectric substrate 12 and heat-treated to melt the cream solder and solder each individual electrode 18 to each lead 7. The individual electrodes 18 may be connected to the leads 7 by using a solder plating layer or a solder ring instead of using the cream solder.

Next, each lead 7 is inserted into each through hole 16 of the second magnetic block 14, and each lead 7 is further inserted into each through hole 8 of the circuit board 1.
, And connect to the wiring conductor 9 with solder 10. At this time, the legs 13b and 13c of the ground plate 13 are also inserted into the through holes 22 and 23 of the circuit board 1 and connected to the ground conductor 21 by the solder 24.

In order to examine the noise absorption effect of the unit filter in the filter assembly 4, the electronic circuit device configured by using the circuit board 1 is a personal computer, and the connector 3 is connected to the interface circuit shown by a broken line in FIG. cable
25 connector terminals 26 were connected, the other end of this cable 25 was kept open, and the amount of radiated noise from 30 MHz to 240 MHz in accordance with FCC regulations was measured by the 3 m method at an open site. For the open site, we excluded external incident broadcast waves and calculated only typical noise levels.
The results shown in Figure (C) were obtained. That is, 60MHz-70MHz,
The clock noise suppressed to about 24 to 30 dBμV / m was observed between 120MHz and 160MHz.

For comparison, when the noise was measured by the same method without the filter assembly 4, the result of FIG. 7 (A) was obtained. Also, instead of the magnetic blocks 11, 14, the outer diameter is 1.
A ferrite bead with a diameter of 9 mm, an inner diameter of 1 mm, and a height of 5 mm was attached to each lead 7, and a 1000 pF individual porcelain capacitor was connected between the lead 7 and ground. Noise was measured in the same way. The results shown in Figure (B) were obtained. When ferrite beads are attached to each lead 7 in FIG. 7 (B), clock noise of about 30 to 40 dBμV / m is observed. Therefore, by using the filter assembly 4 of the present embodiment, it is 10 to 20 dBμV / m as compared with the case of no noise countermeasure of FIG. 7 (A), and compared with the case of ferrite beads of FIG. 7 (B). 5 to 10 dBμV / m is improved. Further, there is also an effect of suppressing noise (interference noise of various noises) that appears between clock noises. The solid line in FIG. 8 shows the clock noise in the case where no noise is taken and the noise in between, and the dotted line shows the noise in this embodiment. As described above, the suppression of the radiation noise means that the conduction noise that enters the external electronic circuit device through the lead 7 and the cable 25 is also suppressed. It also means that noise that enters the electric circuit on the circuit board 1 from the external electronic circuit device through the connector 3 can be suppressed.

The noise absorbing device of this embodiment has the following advantages.

(1) Even if the pitch of the leads 7 of the connector 3 is small, it is only necessary to provide the through holes 15 and 16 corresponding to the leads 7 in the first and second magnetic body blocks 11 and 14, so that the ferrite It can be manufactured more easily than beads.

(2) The volume of ferrite surrounding the lead 3 is
Since the size is larger than that of beads, a large noise absorption effect can be obtained. Further, since the space between the leads 7 is filled with ferrite, the effect of suppressing the electromagnetic interference between the leads 7 becomes large.

(3) Since the through holes 15 and 16 of the magnetic blocks 11 and 14 and the through hole 17 of the dielectric substrate 12 are formed so as to correspond to the leads 7, a large number of leads 7 are formed in the through holes 15 at a time. 16,
Can be inserted in 17. Therefore, the filter assembly 4
Can be easily achieved.

(4) Since the filter assembly 4 is arranged between the main body portion 5 of the connector 3 and the substrate 1, integration with the connector 3 can be easily achieved. In addition, the first and second magnetic substance blocks 1 are formed so that the exposed portions of the leads 7 are reduced.
Since the leads 1 and 14 surround the lead 7, it is possible to suppress the emission of noise from the lead 7.

(5) Since the ground plate 13 is arranged below the dielectric substrate 12,
Not only can the ground be reliably obtained, but the dielectric substrate 12 can be reinforced.

(6) Prepare a connector 3 that can be used for both an electronic circuit device that requires noise prevention and an electronic circuit device that does not, and install the filter assembly 4 only when noise prevention is required. Therefore, the mass productivity of the connector 3 is improved and the cost of the circuit device is reduced.

[Modification] The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example.

(1) The ground plate 13 is provided with a portion 13d that stands up opposite to the legs 13b and 13c, and the key 13e of the rising portion 13d here limits the upper position of the first magnetic body block 11. You may

(2) In order to stabilize the coupling between the main body 5 of the connector 3 and the board 1, a cutout may be provided in the board 1 and a protrusion provided with the main body 5 may be inserted therein.

(3) The connector 3 may be fixed to the circuit board 1 with an adhesive. In addition, the first and second magnetic substance blocks 11 and 14
May be fixed to the lead 7 with an adhesive.

(4) The first and second magnetic substance blocks 11 and 14 may be formed of a mixture of magnetic powder and resin or a magnetic substance other than ferrite.

(5) One of the first and second magnetic body blocks 11 and 14 may be omitted to form an L-shaped filter structure. Further, the number of dielectric substrates 12 having capacitor electrodes is two or more, or two dielectric substrates 12 and one magnetic block 11 are provided.
It is also possible to combine and to form a π-type filter.

(6) Instead of the groove 20, the ground plate 13 may be provided with a hole having a large diameter corresponding to the lead 7.

(7) The dielectric substrate 12 may be provided with a through hole for grounding, a pin connected to the ground conductor 21 of the circuit board 1 may be passed through this through hole, and the ground electrode 19 may be connected to this pin.

[Effects of the Invention] As is apparent from the above, according to the present invention, a circuit device including a filter having a large noise absorption effect can be easily configured.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a part of a circuit device according to an embodiment of the present invention, FIG. 2 is a front view of the circuit device, and FIG. 3 is a part of line III-III in FIG. 4 is a plan view showing a part of a dielectric substrate having individual electrodes, FIG. 5 is a bottom view showing a part of a dielectric substrate having an earth electrode, and FIG. 6 is a T-shaped LC. FIG. 7 is a circuit diagram showing a filter, FIG. 7 is a diagram showing a relationship between frequency and noise level, FIG. 8 is a diagram showing noise level in a part of frequency region, and FIG. 9 is a part of a ground plate of a modified example. FIG. 1 ... Circuit board, 3 ... Connector, 4 ... Filter assembly, 5
... body part, 6 ... coupling part, 7 ... lead, 8 ... through hole, 9 ...
Conductor, 11 ... First magnetic block, 12 ... Dielectric substrate, 13
… Grounding plate, 14… Second magnetic block, 15,16,17… Through hole, 18… Individual electrode, 19… Grounding electrode.

Claims (1)

[Claims] 1. A circuit board (1), a circuit component (2) arranged on the substrate (1), and a connector (3) for connecting an electric circuit including the circuit component (2) to an external circuit. A circuit in which the connector (3) has a plurality of leads (7) led out from a connector body (5), and the leads (7) are electrically connected to the substrate (1). In the device, a plurality of through holes (1) corresponding to the leads (7) are provided between the main body (5) of the connector (3) and the substrate (1).
A magnetic block or blocks (11) (1) having
4) and a plurality of through holes (1) corresponding to the leads (7).
7) and at least one dielectric substrate (12) provided with a plurality of individual electrodes (18) for obtaining a plurality of capacitors and a ground electrode (19), and the leads ( 7) through the through holes (15) of the magnetic block (11) (14) and the through hole (17) of the dielectric substrate (12), and connecting the individual electrodes (18) to the leads (7). A circuit device, wherein the ground electrode (19) is connected to the ground conductor (21) of the circuit board (1) by a conductor member.