JPH05121891A - Printed wiring board - Google Patents

Abstract

PURPOSE:To provide a printed wiring board capable of effectively taking a countermeasure to noises for a loaded electronic circuit while enabling the miniaturization of the whole printed wiring board. CONSTITUTION:Distributed constant type LC noise filters 20 are connected in series with the power line or signal line of a gate array 14 loaded on a printed wiring board 100 and a signal line through a connector 15 for a modem, a connector 16 for a printer, a connector 17 for a keyboard and an LCD driving cable 18. Accordingly, noises intruding from the outside into an electronic circuit in the printed wiring board 100 and noises generated in the printed wiring board 100 are damped and eliminated excellently by the distributed constant type LC noise filters 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a printed wiring board,
In particular, the present invention relates to a printed wiring board with noise countermeasures.

[0002]

2. Description of the Related Art With the development of electronic technology in recent years, electronic circuits have been widely used in various fields. Therefore, it is possible to operate these electronic circuits in a stable and reliable manner without being affected by the outside. desired.

However, noise enters the electronic circuit directly or indirectly from the outside. For this reason,
There is a problem that various electronic devices that use electronic circuits often cause post-operation.

In particular, electronic circuits often use a switching regulator as a DC power source. Therefore, due to transient current such as switching, or due to load fluctuation due to switching operation of the digital IC used,
Large noise with various frequency components is often generated in the power line of the switching regulator. Then, these noises are propagated to other circuits in the same device through the power supply line or by radiation, and malfunction or S
This may have a bad effect such as a decrease in the / N ratio, and may cause a malfunction of an electronic device that is being used even closer.

For this reason, in the conventional printed wiring board, an LC noise filter is mounted on the power supply line or the signal line of the electronic circuit as required to take measures against noise.

As this LC noise filter, for example, as shown in FIG. 9A and an equivalent circuit in FIG. 9B, two sets of windings 72 and 74 are wound around a core 70, and these windings are wound. It is known that capacitors 76 and 78 are connected in parallel to both ends of the lines 72 and 74, respectively.

In addition, the noise filter disclosed in Japanese Patent Laid-Open No. 56-50507 is known. In this composite electronic component according to the related art, as shown in FIG. 10, a laminated body is formed by forming a plurality of insulating layers 80a, 80b, 80c and the like. And each said insulator layer 80
Conductive patterns 82a, 82b, between layers a, 80b, etc.
82c is provided to form a coil L having a predetermined number of turns. In addition, conductive layers 84a and 84b are arranged between the insulating layers 80a and 80b and the like and spaced from the circumferential conductive patterns 82a and 82c, and the conductive layers 84a and 84b are disposed.
A capacitance C is formed between a and 84b and the conductive patterns 82a and 82c.

As a result, L and C as shown in FIG.
A lumped constant type noise filter consisting of Further, in this conventional technique, since L and C are incorporated in the laminated body, it can be used as a small and lightweight LC noise filter.

[0009]

The LC noise filter of the type in which the winding is wound around the above-described conventional core 70, the core 70 and the windings 72, 7 that form the inductor are used.
4 is large, and since the inductor and the capacitors 76 and 78 are formed as separate parts, the entire filter is large, which is unsuitable for mounting on a printed wiring board for electronic circuits. However, there is a problem in that it is not possible to satisfy the demand for reduction in size and weight of electronic devices.

Further, in this type of LC noise filter, since L and C are formed as lumped constants, good attenuation characteristics cannot be obtained, and noise countermeasures are not sufficient.

In addition, an L type in which conductive patterns are laminated
The C noise filter has a conductive pattern 8 forming a coil.
The conductive layers 84a and 84b forming a capacitance are simply provided adjacent to the linear portions of the portions 2a and 82c. For this reason, the capacitance C between the coil and the conductive layer 84 is extremely small, and the capacitance is formed in a lumped constant. Therefore, good attenuation characteristics cannot be obtained, and the electronic circuit mounted on the printed wiring board cannot be obtained. There was a problem that noise countermeasures were not sufficient.

The present invention was created in view of the above points, and can effectively take measures against noise in an electronic circuit mounted therein, and at the same time, it is possible to downsize the entire printed wiring board. It is intended to provide a printed wiring board.

[0013]

In order to solve the above-mentioned problems, the printed wiring board of the present invention is a printed wiring board for mounting an electronic circuit, and a distributed constant is provided on at least one of a signal line and a power supply line of the electronic circuit. A type LC noise filter is provided.

[0014]

In the present invention, noise generated from the outside or inside the printed wiring board that tries to enter the electronic circuit mounted on the printed wiring board is a distributed constant provided in the signal line or power supply line of the electronic circuit. Type LC
Since it is attenuated and removed by the noise filter, the mounted electronic circuit can operate stably without being affected by noise.

Further, even if noise generated from an electronic circuit is mixed in the signal line, this noise is attenuated and removed by the distributed constant type LC noise filter, and the noise is removed to another electronic circuit in the printed wiring board or to the printed wiring board. Output to the outside is prevented in advance.

As described above, according to the present invention, the noise penetrating into the electronic circuit mounted on the printed wiring board and the noise generated by the electronic circuit are removed, and the noise countermeasure of the mounted electronic circuit is effectively performed. It becomes possible.

Particularly, in the present invention, the distributed constant type L
The C noise filter includes a laminated body in which a plurality of insulating layers are laminated, and a plurality of conductors that circulate between the layers of the laminated body from one layer to another layer and face each other with an insulating layer interposed therebetween. It is preferable that each of the conductors independently functions as an inductor and is formed as a laminated filter in which capacitors are formed between the conductors in a distributed constant manner.

As a result, the capacitors and coils forming the LC noise filter are integrally formed, the LC noise filter can be downsized, and the entire printed wiring board can be downsized.

Further, in the present invention, it is preferable that the laminated filter is formed on the printed wiring board by using a film forming technique or a printing technique. This allows the printed wiring board itself to
LC noise filter will be built in where necessary,
It is possible to further reduce the size of the printed wiring board with noise countermeasures.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

First Embodiment FIG. 1 shows a preferred embodiment of a printed wiring board to which the present invention is applied. Printed wiring board 10 shown in FIG.
0 is used for a personal computer, a word processor or the like, and all processing functions such as a central processing unit (CPU) and a memory are mounted on one board.

In the printed wiring board 100, various electronic components are arranged and wired on a substrate made of ceramics or glass epoxy resin, etc., and constitutes a main part of an electronic circuit for a personal computer or a word processor as a whole. ing. The electronic components mounted on the printed wiring board 100 include the CPU 10, the memory 12, the gate array 14, various input / output ICs, and the like. The various input / output ICs are connected to the input / output devices via the various interfaces shown in FIG. Specifically, it is connected to an external modem (not shown) via the modem connector 15, connected to a printer (not shown) via the printer connector 16, and a keyboard via the keyboard connector 17. (Not shown), L
It is connected to an LCD (not shown) provided by a CD (liquid crystal display) drive cable 18.

Further, the printed wiring board 100 of the embodiment is
Distributed constant type LC noise filter 2 shown by the dotted line in FIG.
It has 0. The LC noise filter 20 uses a film forming technique or a printing technique to print the printed wiring board 100.
It is formed integrally with. In this embodiment, on the power supply line and signal line of the gate array 14, on the signal line via the modem connector 15, on the signal line via the printer connector 16, and the keyboard connector 1.
On the signal line via 7 and the LCD drive cable 18
The LC noise filter 20 is inserted in series on the signal line via.

As a result, it is possible to effectively remove the noise that enters the gate array 14 via the power supply line or the input signal line and the noise included in the signal output to the output signal line. In addition, noise included in a signal output from the signal line to the outside through the connectors 15 and 16 is effectively removed, which tends to enter the signal line through the modem connector 15 and the printer connector 16. be able to. Also,
It is possible to effectively remove noise that tends to enter the signal line via the keyboard connector 17. Further, it is possible to effectively remove the noise included in the drive signal output via the LCD drive cable 18.

In particular, since the LC noise filter 20 is formed as a distributed constant type LC noise filter, a better attenuation characteristic can be obtained as compared with the case where a lumped constant type LC noise filter is used. It becomes possible to satisfactorily remove various noises. Further, since the LC noise filter 20 is integrally formed by a film forming technique or a printing technique, compared with a case where a winding is wound around a core or a noise filter is formed by combining a coil and a capacitor, the device itself is Can be downsized,
As a result, the printed wiring board 100 can be downsized as a whole. In particular, recently, personal computers and word processors also tend to be downsized from desktop types to laptop types and notebook types.
The miniaturization of 00 makes it possible to easily cope with, for example, development of a notebook type and high functionality.

The LC noise filter 20 of the present embodiment is arranged such that a plurality of insulating layers are laminated, and the LC noise filter 20 circulates from one layer of the laminated body to another layer and is opposed to each other with an insulating layer interposed therebetween. Each of the conductors includes a plurality of conductors, and each conductor independently functions as an inductor and is formed as a laminated filter in which capacitors are formed between the conductors in a distributed constant manner.

Examples of such distributed constant type LC noise filters are, for example, Japanese Patent Application No. 2-11540 and Japanese Patent Application No. 2-140.
7590, Japanese Patent Application No. 2-143427, Japanese Patent Application No. 2-227
360, Japanese Patent Application No. 2-411247, Japanese Patent Application No. 2-2805
21 and Japanese Patent Application No. 3-50600 can be used.

In this embodiment, the LC noise filter 20 is formed integrally with the printed wiring board 100, as shown in FIG. Therefore, the printed wiring board 10
After forming this LC noise filter 20 as a part of 0, various electronic parts can be arranged on it.

2 to 5, a thin film forming technique is used.
A preferred example of the manufacturing process of the laminated LC noise filter 20 is shown. Although the laminated LC noise filters 20 corresponding to the signal lines and the power supply lines respectively are formed at the same time, only one LC noise filter 20 is illustrated here for easy understanding. The description of the other LC noise filters 20 is omitted. The printed wiring board 100 shown in FIGS.
Shows a part (dotted line part) of the printed wiring board 100 shown in FIG. 1.

In the LC noise filter 20 of the embodiment, first, as shown in FIG. 2A, the second conductive element 54-1 is formed on the surface of the printed wiring board 100 so as to be wound counterclockwise.

Next, as shown in FIG. 2B, the second conductive element 54-1 is formed on the surface of the printed wiring board 100.
The insulating thin film 200-1 is formed by coating so as to expose the ends of the.

Next, as shown in FIG. 2C, a second conductive element 54-2 electrically connected to the second conductive element 54-1 is formed by coating. At the same time,
The second conductive element 54 through the insulating thin film 200-1.
The first conductive element 44-1 opposite to -1 is formed by coating.

Next, as shown in FIG. 2D, an insulating thin film 200-2 is formed by coating so that the end portions of the conductive elements 54-2 and 44-1 are exposed.

Next, as shown in FIG. 3A, the conductive elements 44-1 and 54 are formed on the insulating thin film 200-2.
-2 and the second conductive element 54-3 and the first conductive element 44-2 are formed so as to face each other via the insulating thin film 200-2.

The thin film forming step and the element forming step are repeated as shown in FIGS. 3 (b) to 4 (b) to form the laminated body 30.

In this way, the laminated LC noise filter 20 is formed, and the terminals 42a, 42b (first conductive element 44-1, 4-1, which appear on the printed wiring board 100) are formed.
44-4) is inserted in series to the signal line or the power supply line, and the terminal 52 (one end of the second conductive element 54) is grounded.

Thereby, as shown in FIG. 5, in the laminated LC noise filter 20 of the embodiment, both ends of the first conductor 40 constituted by the first conductive element 44 are connected to the terminals 42a and 42b. Thus, it functions as a coil having a predetermined inductance L1. Similarly, one end of the second conductor 50 formed by the second conductive element 54 has a ground terminal 52a.
And functions as a coil having a predetermined inductance L2.

Moreover, as described above, it is presumed that the capacitance C is formed between the first and second conductors 40 and 50 substantially continuously and in a distributed constant manner.

Therefore, the laminated LC noise filter 20 of the present invention can exhibit excellent characteristics that the conventional lumped constant LC noise filter 20 does not have.
By using the C noise filter 20 as an LC noise filter, excellent attenuation characteristics can be exhibited over a wide band.

In addition to this, according to the present invention, the first and second conductors 40 and 50 face each other with the insulating thin film 200 interposed therebetween. Therefore, the conventional laminated type L shown in FIG.
A capacitance C that is sufficiently larger than that of a C noise filter
From this point, it can be understood that it can be used as an LC noise filter having better attenuation characteristics than the conventional laminated LC noise filter.

Further, by forming the distributed constant type LC noise filter 20 as in this embodiment on the printed wiring board 100 by using the film forming technique, the number of parts can be increased without increasing the number of parts.
Good noise countermeasures can be taken.

The LC noise filter 20 of each of the above-mentioned embodiments functions as a capacitor conductor as required by the second.
The conductor 50 may be divided into a plurality of parts, and one end side of each divided section may be connected to the ground terminal 52a.

Second Embodiment Next, a preferred second embodiment of the printed wiring board of the present invention will be described. The members corresponding to those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the first embodiment, the distributed constant type LC noise filter 20 is a laminated type filter using a film forming technique. On the other hand, the present embodiment is characterized in that a chip type filter is used as shown in FIG.

7 and 8 show a preferred example of the chip type LC noise filter 20 used in the circuit of this embodiment. The LC shown in FIG. 7 and FIG.
The noise filter 20 is one of a plurality of LC noise filters 20 used for each signal line and power supply line in FIG. 6.

As shown in FIG. 7, the LC noise filter 20 of the embodiment has a plurality of insulating plates 32-1, 32-2 ... 32-
A laminated body 30 formed by laminating 4 and the insulating plate 32.
Between the first conductor 40 which is provided in the interlayers 36-2, 36-3, 36-4 and forms a coil of a predetermined number of turns and the interlayers 36-1, 36-2, 36-3 of the insulating plate 32, The second conductor 50 is provided so as to face the first conductor 40 via the insulating plate 32.

Each of the insulating plates 32 may be formed by using various insulating materials as needed. In the embodiment, it is formed by using ceramics.

In the laminated body 30 of the embodiment, in order to prevent the first conductor 40 and the second conductor 50 from being short-circuited, the insulating plates 30 are connected to the interlayer insulating sheets 34-1, 34-2, 34-.
It is laminated through 3.

The first conductor 40 is formed on the surfaces of the uppermost insulating plate 32-1 and the lowermost insulating sheet 34-3.
42a, 42b of the second conductor 50 and the terminal 52a of the second conductor 50
Are coated.

Further, the first conductor 40 and the second conductor 50 have the interlayers 36-1, 36-2, ... Of the insulating plate 32.
36-4 includes a plurality of first conductive elements 44-1 and 44- that continuously circulate from one layer to another layer.
2, 44-3 and the second conductive element 54-1,
It is composed of 54-2 and 54-3.

A characteristic feature here is that the first and second conductive elements 44 and 54 are connected to the insulating plate 32.
It is to face each other via and to form a capacitance between them substantially continuously.

As a result, the first and second conductors 40,
Each of the capacitors 50 functions as a coil having a predetermined number of turns, and a capacitance C is formed substantially continuously between the first and second conductors 40 and 50 via the insulating plate 32. 1 and 2
It is presumed that the conductors 40 and 50 are formed in a distributed constant manner.

Here, the first and second conductive elements 44 and 54 of the embodiment are coated and formed on both surfaces of the insulating plate 32 so as to face each other by using a method such as printing, vapor deposition, plating or the like. There is. In addition, the conductive pattern 4 for connection
6, 56 are also formed by coating on the insulating plate 32.

The terminal 52a formed on the surface of the insulating plate 32-1 is connected to the insulating plate 32 through the through hole 33.
-2 is connected to the second conductive element 54-1 provided above.

Similarly, one of the input terminals 42-b provided on the surface of the insulating plate 32-1 is connected to each of the insulating plates 32-1 and 32.
-2 is connected to the end portion of the first conductive element 44-1 provided on the back surface side of the insulating plate 32-2 via the through hole 33 and the conductive pattern 46 provided on the -2 side. Similarly, the other input / output terminal 42a provided on the lowermost interlayer insulating sheet 34-3 is covered with the first conductive element 44-3 on the insulating plate 32-4 through the through hole 35. It is connected to the.

Further, the insulating plates 32-2, 32-3, 32
-4, the first conductive element 44 and the second conductive element 54, which are formed by coating, are formed on these insulating plates 3 respectively.
Through hole 33, conductive pattern 4 formed on 2
6, 56 and through holes 35 provided on the interlayer insulating sheet 34, from one interlayer 36 to another interlayer 3
It is electrically connected to circulate over 6.

As a result, the three-terminal type L having the distributed constant type equivalent circuit composed of L and C as shown in FIG.
The C noise filter 20 can be obtained. Therefore, the LC noise filter 20 of the present embodiment can exhibit good attenuation characteristics over a wide band.

The LC noise filter 20 of this embodiment is used.
Is used as a normal mode type, but it can also be used as a common mode type by providing input / output terminals 52a at both ends of the second conductor 50 if necessary.

FIG. 8 is an external perspective view of the normal mode LC noise filter 20 thus formed. In the embodiment, after the insulating plate 32 and the interlayer insulating sheet 34 shown in FIG. 7 are laminated and fixed to form the laminated body 30, the input terminals 42a, 42a formed on the front surface and the back surface side of the laminated body 30 are connected. A conductive material is coated so as to function as one terminal. Similarly, input / output terminal 4
2b and 42b are also coated with a conductive material so as to function as one terminal. Further, similarly, the terminal 52a is also covered with a conductive material.

As a result, a three-terminal type noise filter in which two input / output terminals 42a and 42b and one ground terminal 52 are provided on the outer peripheral surface of the laminated body 30 is formed. Moreover, since this noise filter is formed as an SMD type (surface mount device) element, its handling becomes extremely easy.

Third Embodiment Next, another example of the distributed constant type LC noise filter 20 used in the printed wiring board of the present invention will be described in Japanese Patent Application No. 2-28.
The filter according to 0521 will be described as an example. In addition,
Although the laminated body 30 is formed by laminating the insulating plates in each of the embodiments, the present embodiment is characterized in that the dielectric sheet is folded together with the conductor to form the laminated body.

12 and 13 show a preferred example of the chip type LC noise filter used in the circuit of this embodiment.

Example When manufacturing the LC noise filter, first, the first insulating sheet 120 shown in FIG. 13 is formed. The first insulating sheet 120 has a plurality of folding parts 122-1 122-2 ...
8 are continuously arranged via the bent portion 124. Perforations are formed in advance on each of the bent portions 124 in order to facilitate the bending. Also,
The folding part 122 of the embodiment is formed in a square shape, but if it is laminated with each other when folded, the shape thereof can be arbitrarily formed.

Then, the first conductor 40 and the second conductor 50 having the pattern shown in FIG. 13 are provided on the front surface 120a side and the back surface 120b side of the first insulating sheet 120.

The first conductor 40 is a ring-shaped conductor for inductors, a part of which is cut away on the surface 120a side of each of the folded portions 122-1 122-2 ... 122-8 which are continuously arranged. 142-1, 142-2 ... 142-7 are provided alternately and continuously in the opposite direction, and the first insulating sheet 2
A coil having a predetermined number of turns (4 turns in the embodiment) is formed when 0 is alternately folded and laminated in the opposite direction as shown in FIG. Input / output terminals 42a and 42b are provided at both ends of the first conductor 40.

Further, the second conductor 50 is provided with capacitor conductors 156-1 and 156-2 provided on the back surface side 20b of each of the folded portions 122-1 122-2 ... 122-7.
... 156-7. The capacitor conductors 156-1, 156-2, ... 156-7 are continuously provided so as to face the inductor conductors 142-1, 142-2, ... 142-7, and the first conductor 40 is provided. Forms a capacitance between and. And this conductor 5
The zero end side extends from the folded portions 22-7 to the center of 22-8, and the grounding terminal 52a is provided there.

The conductors 40 and the conductors 50 of this embodiment are
Is coated with an insulating layer on its surface, the conductor 5
Instead of forming an insulating layer on the surface of No. 0, a second insulating sheet 130 having the same structure as the first insulating sheet 120 is prepared.
0 may be laminated and adhered so as to be sandwiched between them. In addition, in order to simplify the following description, the following description will be given by taking the case where the second insulating sheet 130 is not used as an example.

Next, the conductor 40 and the conductor 50 are formed on both surfaces of the conductor 40.
As shown in FIG. 12 (A), the insulating sheet 120 coated with is bent in a zigzag shape through the bent portion 124, and the folded portions 122-1 122-2 ... 122-8 are laminated. As a result, the laminated body 30 shown in FIG.
Is formed. As a result, the partially cut ring-shaped conductors 142-1, 142-2 ... 142-7 overlap each other to form a coil in which one conductor wire is wound a plurality of turns (4 turns in the embodiment), It will function as an inductor having the inductance L1. At the same time, the conductor 50 is connected to the first conductor 40 and the insulating sheet 1.
They face each other through 20, and form a capacitance C therebetween.

Therefore, this LC noise filter is shown in FIG.
It functions as a three-terminal LC noise filter having an equivalent circuit as shown in FIG.

Next, as shown in FIG. 1 (C), this laminated body 30 is molded with a resin such as epoxy except for the terminals 42a, 42b and 52a to form a final LC noise filter. To do.

As described above, according to the LC noise filter of the present embodiment, the first insulating sheet 12 having the first conductor 40 and the second conductor 50 coated on both surfaces thereof is formed.
By folding 0 in a zigzag shape through the bent portion 124, a flat cubic shape is formed. For this reason, it is smaller and lighter than the conventional LC noise filter, and is extremely suitable as an electronic circuit component which has recently been required to be smaller and lighter.

The noise filter used in the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention.

For example, in each of the above-described embodiments, the case where the conductors face each other via the insulating layer has been described as an example. However, even if the conductors do not completely face each other, the capacitance is distributed between them. If they are formed in a constant number, there may be a deviation in the position where they face each other. Further, in each of the above-described embodiments, the case where a laminated filter is used as the LC noise filter 20 has been described as an example, but the present invention is not limited to this, and various distributed constant types other than this may be used as necessary. An LC noise filter can be used.

Further, in the above embodiment, the case where the noise on the signal input / output to / from the outside of the printed wiring board 100 was mainly considered was considered, but the present invention is not limited to this, and for example, on the printed wiring board 100. The LC noise filter 20 may be provided on the signal input / output line between the electronic components. In particular, when the printed wiring on the printed wiring board 100 is long, noise is likely to occur, and it is necessary to take such a noise countermeasure.

The present invention can be applied not only to personal computers and word processors, but also to various electronic devices, for example, monitor devices such as facsimile machines and televisions.

As described above, according to the present invention,
The noise generated from the outside or inside the printed wiring board, which tends to enter the electronic circuit mounted on the printed wiring board, can be removed by the distributed constant type LC noise filter provided in the signal line or the power supply line. In particular, since the LC noise filter used in the present invention is formed as a distributed constant type filter, it is more effective as a noise countermeasure for the electronic circuit mounted on the printed wiring board than when using a lumped constant type filter. Can be done.

According to the invention of claim (2), the LC
Since the coil and the capacitor that form the noise filter are integrally formed and can be downsized, the entire printed wiring board can be downsized as compared with the case where a filter including a plurality of discrete components is used.

Further, as in the third aspect of the present invention, the LC noise filter is laminated on the printed wiring board by using the film forming technique or the printing technique, whereby the filter can be built on the printed wiring board. Therefore, the entire printed wiring board can be made more compact, and since it is not necessary to attach the LC noise filter as a separate component on the surface of the printed wiring board, the wiring board itself can be handled easily.

Further, according to the invention of claim 4, by forming the LC noise filter as an SMD type, it becomes possible to automatically mount the LC noise filter on the printed wiring board.

[Brief description of drawings]

FIG. 1 is an external perspective view of a printed wiring board according to the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process of a distributed constant type LC noise filter used for the printed wiring board shown in FIG.

FIG. 3 is an explanatory diagram of a manufacturing process of a distributed constant type LC noise filter used for the printed wiring board shown in FIG. 1.

FIG. 4 is an explanatory diagram of a manufacturing process of a distributed constant type LC noise filter used for the printed wiring board shown in FIG. 1.

FIG. 5 is an equivalent circuit diagram of the distributed constant type LC noise filter shown in FIGS.

FIG. 6 is an external perspective view for explaining another embodiment of the present invention.

7 is an exploded perspective view showing a distributed constant type noise filter used in the printed wiring board shown in FIG.

FIG. 8 is a perspective view showing the appearance of the LC noise filter shown in FIG. 7 in an assembled state.

9A and 9B are explanatory views of a conventional LC noise filter, FIG. 9A is an explanatory view of a specific configuration, and FIG. 9B is an equivalent circuit diagram thereof.

10A to 10F are explanatory views showing an example of a manufacturing process of a conventional laminated LC element.

11 is an equivalent circuit diagram of the LC noise filter shown in FIG.

FIG. 12 is an explanatory diagram of a distributed constant type noise filter used in the printed wiring board of the present invention.

FIG. 13 is an exploded perspective view of the noise filter shown in FIG.

[Explanation of symbols]

10 Central Processing Unit (CPU) 12 Memory 14 Gate Array 15 Modem Connector 16 Printer Connector 17 Keyboard Connector 18 Liquid Crystal Display (LCD) Drive Cable 20 LC Noise Filter 100 Printed Wiring Board
IK013201

Claims (4)

[Claims] 1. A printed wiring board for mounting an electronic circuit, wherein a distributed constant type LC noise filter is provided on at least one of a signal line and a power supply line of the electronic circuit. 2. The distributed constant type LC noise filter according to claim 1, wherein the plurality of insulating layers are laminated, and a layered body is wound from one layer to another layer, and is insulated from each other. A plurality of conductors facing each other through a layer, and each conductor functions as an inductor by itself, and is formed as a laminated filter in which capacitors are distributedly formed between the conductors. Characterized printed wiring board. 3. The printed wiring board according to claim 2, wherein the distributed constant type LC noise filter is laminated and formed on the printed wiring board using a film forming technique or a printing technique. 4. The printed wiring board according to claim 2, wherein the distributed constant type LC noise filter is formed as an S, M, D type filter.