JPH02217012A - Noise filter for face mounting - Google Patents

Abstract

PURPOSE:To improve a noise reducing effect and to easily produce the noise filter by arraying noise filters by means of a bonding mold to constitute the filters as a single part moded as a chip. CONSTITUTION:Plural chip type capacitors 5 are used for capacitors constituting respective noise filters, a multi-hole type ferrite block 3 in common with respective filters is used for ferrite and a common ground pattern 2b is used to connect plural capacitors 5 to the ground. Thereby, respective noise filters can be easily produced, arrayed by using the bonding mold 4 and constituted as a single part moded as a chip. Consequently, connection between the capacitors and the ground can be minimized, the generation of a harmful inductance component can be prevented and noise on a signal line can be effectively reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface-mount noise filter that reduces noise generation in electronic equipment using a surface-mount board.

[Prior Art] In order to reduce noise generated from the main body and the cables connected to it, many electronic devices insert ferrite beads or capacitors on the signal pattern of the circuit to form a noise filter. We are trying to reduce the When forming such noise filters on a plurality of signal lines, the filters are integrated for the purpose of increasing the efficiency of pattern design and improving processability.

A conventional noise filter for surface mounting of this type is shown in FIGS. 6 to 10 and disclosed in, for example, Japanese Unexamined Utility Model Publication No. 136419/1983. FIG. 6 is a perspective view showing the external structure of a conventional surface-mount noise filter, and FIG. 7 is a side sectional view thereof. In each figure, (1a) is a signal connection terminal, (1b) is a signal lead, (2a) is a ground connection terminal, (6) is a ferrite bead, (7) is an electrode, (8
) is a dielectric substrate, and as shown in the equivalent circuit of FIG. 8, an inductor (9) is formed with ferrite beads (6), and a capacitor (1
0) is formed.

Conventional surface-mount noise filters are configured as shown in Figures 6 and 7, and are installed on the signal pattern of electronic equipment to eliminate unnecessary high frequencies contained in the signal, as shown in Figure 8. The component is attenuated by an inductor (9) formed of ferrite beads (6), and bypassed to ground by a capacitor (10) formed of an electrode (7) and a dielectric substrate (8). Therefore, unnecessary noise components generated from electronic equipment and the cables connected thereto are removed from the signal line, and only the necessary signal components are transmitted after passing through the noise filter, reducing noise. .

[Problems to be Solved by the Invention] As described above, the conventional surface-mount noise filter as described above separates the ferrite beads and the electrodes on the dielectric substrate, which are each configured as a single component, from each signal line. Therefore, as the number of signal lines on the surface mount board increases and the density increases, the number of parts increases, and the device becomes larger and cannot be used on a fine surface mount board.

Furthermore, each component constituting the noise filter must be mounted and manufactured one by one, resulting in a complicated manufacturing process and a large area occupied on the board.

Furthermore, as the circuit becomes more complex, the pattern length from the ground connection terminal to the ground becomes longer, resulting in the formation of an inductance component (L) as shown in the equivalent circuit in Figure 9, and as shown in Figure 10. It becomes impossible to obtain a sufficient noise reduction effect.

Furthermore, in some cases, a resonant circuit may be formed between the capacitor (10) and this inductance component (L), and there is even a risk of increasing noise.

The present invention was made to solve this problem, and aims to provide a surface-mount noise filter that has a high noise reduction effect, can be easily manufactured, and occupies a small area on a substrate.

[Means for Solving the Problems] The surface-mount noise filter according to the present invention uses a plurality of chip capacitors as the capacitors constituting each noise filter, and uses a multi-hole ferrite block common to each noise filter as the ferrite. We decided to use a common ground pattern to connect multiple chip capacitors and the ground.

[Operation] In this invention, a plurality of chip capacitors are used as the capacitors constituting each noise filter, a multi-hole ferrite block common to each noise filter is used as the ferrite, and the plurality of chip capacitors and the ground are connected. Since we decided to use a common ground pattern, we used an adhesive mold to create an array.
It becomes possible to configure it as a single component molded into one chip.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
5 to 5 are diagrams showing the configuration of the surface-mount noise filter in this embodiment, respectively. FIG. 1 is a perspective view, and FIG.
The figure is a plan view, Figure 3 is a front view, Figure 4 is a side view, and Figure 5 is an exploded perspective view. In each figure, (1a) is a signal connection terminal, (1b) is a signal lead, (2a) is a ) shows a ground connection terminal, (2b) a ground pattern, (3) a multi-hole ferrite block, (4) an adhesive mold, and (5) a chip capacitor.

As shown in FIG. 5, the surface-mount noise filter in this embodiment has chip capacitors (5) placed on each ground pattern (2b), and signal leads (
lb) for electrical continuity, and connect the signal lead (
Each person should use a multi-hole ferrite block (3) with holes equal to the number of holes in 1b).
) are passed through and fixed with adhesive on both sides.

That is, in this invention, by using the ferrite block (3), filter circuits for the required number of signal lines (4 in the embodiment) are arrayed and configured as a single component molded into one chip. There is. Therefore, the ground pattern (2b) can be built in with the shortest length, and even when mounting on multiple signal lines, the ground connection terminal (2a) can be used to connect the capacitor (5) and the ground in the shortest possible length. can be connected, prevent the generation of harmful inductance components, and obtain a filter effect similar to the designed filter effect as shown in Figures 8 and 10, effectively suppressing noise on the signal line. can be reduced to

In addition, since the entire structure is molded into a single component, the number of components can be reduced when assembling electronic equipment, and mounting on a surface-mounted board can be done easily and with a small footprint. . Furthermore, by using the multi-hole ferrite block (3) and the chip capacitor (5), it becomes easy to create the noise filter itself.

In the above embodiment, the filter circuit is composed of four circuits, but it may be composed of a necessary number of circuits according to the number of signal lines.

[Effects of the Invention] As explained above, the present invention uses a plurality of chip capacitors as the capacitors constituting each noise filter,
A multi-hole ferrite block that is common to each filter is used for the ferrite, and a common ground pattern is used to connect multiple chip capacitors to the ground, making it easy to manufacture and requiring no adhesive mold. It is now possible to configure the capacitor as an array and as a single component molded into one chip, allowing the shortest connection between the capacitor and ground, preventing the generation of harmful inductance components, and effectively reducing noise on the signal line. In addition, the number of parts can be reduced when assembling an electronic device, the area occupied when mounting on a surface mount board can be reduced, and mounting can be facilitated.

[Brief explanation of the drawing]

FIGS. 1 to 5 are diagrams for explaining an embodiment of the present invention, and FIGS. 6 to 10 are diagrams for explaining a conventional surface-mount noise filter, respectively. (1a) is a signal connection terminal, (1b) is a signal lead,
(2a) is a ground connection terminal, (2b) is a ground pattern, (3) is a multi-hole ferrite block, (4) is an adhesive mold, and (5) is a chip capacitor. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A plurality of noise filters formed by combining a capacitor and a ferrite are integrated, and each of the above-mentioned noise filters is connected to each signal line that requires a noise filter on a surface mount board. In a surface mount noise filter that aims to reduce noise on a line, a plurality of chip capacitors used as capacitors constituting the plurality of noise filters are placed on the top surface and directly connected. It has one common grounding pattern that electrically connects each of these chip-type capacitors and the ground, and a plurality of holes through which each signal lead connected to each of the plurality of chip-type capacitors passes through. A multi-hole type ferrite block common to the plurality of noise filters is provided, which is integrated with each of the chip capacitors and the grounding pattern by passing each signal lead through these holes, and the multi-hole type ferrite block that is common to the plurality of noise filters is integrated with each of the chip type capacitors and the grounding pattern. A noise filter for surface mounting, characterized in that a plurality of chip-type capacitors, the grounding pattern, and the multi-hole ferrite block are arrayed and molded into one chip as a single component.