JP7320341B2 - wiring board - Google Patents

Description

The present invention relates to a multi-layer wiring board in which insulating layers and conductor layers are alternately laminated.

2. Description of the Related Art Conventionally, multilayer wiring boards are widely known in which insulating layers and conductor layers are alternately laminated, and signal wiring and ground wiring are formed on each conductor layer. This type of wiring board is generally used for transmission of high-frequency signals, and it is desirable to suppress the influence of noise on signal wiring as much as possible. As a measure for this, for example, as shown in FIG. 2 of Patent Document 1, signal wiring formed in a conductor layer above an insulating layer and ground wiring formed in a conductor layer adjacent to that conductor layer. A wiring board structure has been proposed in which a high dielectric constant portion is formed in an area between the wiring substrates. By adopting such a structure, noise due to high-frequency signals can be reduced by interposing a region with a high dielectric constant between the signal wiring and the ground wiring.

JP 2003-289184 A

When applying the above-described conventional technology to a wiring board, no particular structural problem occurs when manufacturing by a build-up method using an insulating layer made of resin. When forming a high dielectric constant portion (FIG. 2 of Patent Document 1), there is a possibility of causing structural problems. Specifically, when a hole corresponding to a high dielectric constant portion is filled with a high dielectric constant material during the fabrication of a wiring board, there is a risk that a gap may be formed between the high dielectric constant portion and the upper and lower wiring due to insufficient filling. (see Figure 4). Since the dielectric constant of such a gap is almost the same as that of air, the effective dielectric constant between vertically opposed wirings is lowered. Also, if lamination misalignment of each layer occurs in the lamination process of the wiring board, the position of the wiring and the high dielectric constant portion that face each other vertically will be misaligned, resulting in a state in which part of the wiring does not overlap the high dielectric constant portion (see FIG. 5). , the part becomes susceptible to noise.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a wiring board can be produced while suppressing the influence of noise by covering a pair of wirings formed on the wiring board with a pair of high dielectric constant portions. Disclosed is a wiring board that can prevent deterioration in performance due to a gap between a high dielectric constant portion and a wiring and lamination misalignment in a lamination process.

In order to solve the above problems, the wiring board of the present invention comprises a first conductor layer (21) having a first wiring (30) and a predetermined insulating layer (21) laminated on the first conductor layer ( 11), and a second conductor layer (22) laminated on the first conductor layer with the predetermined insulating layer interposed therebetween and having a second wiring (31), the wiring board comprising: a first high dielectric constant portion (50) having a dielectric constant higher than that of a predetermined insulating layer and covering at least the predetermined insulating layer side of the first wiring; a second high dielectric constant portion (51) having a higher dielectric constant than the dielectric constant and covering at least the predetermined insulating layer side of the second wiring; The second wiring is arranged to face each other in the thickness direction with the first high dielectric constant portion, the predetermined insulating layer, and the second high dielectric constant portion interposed therebetween. there is

According to the wiring board of the present invention, in the multilayer wiring board, the first and second conductor layers adjacent to each other with a predetermined insulating layer interposed therebetween include the first conductor layer covered with the first high dielectric constant portion. A wiring and a second wiring covered with a second high dielectric constant portion are arranged to face each other. It has the effect of suppressing noise in high-frequency signals. Since the first and second wirings have a structure in which the first high dielectric constant portion, the predetermined insulating layer, and the second high dielectric constant portion are sandwiched in the thickness direction, a predetermined wiring board can be fabricated. Even if ceramics are sometimes used, gaps due to poor filling of high-permittivity materials are less likely to occur, and misalignment due to lamination misalignment is less likely to occur, thereby reliably reducing noise while maintaining high reliability. can do.

In the present invention, in plan view in the thickness direction, the first high dielectric constant portion is arranged in a region including the first wiring, and the second high dielectric constant portion includes the second wiring. placed in the area. In this case, the first high dielectric constant portion covers the surface and side surfaces of the first wiring facing the predetermined insulating layer, and the second high dielectric constant portion covers the predetermined insulating layer of the second wiring. Cover the surface and sides facing the layer. By arranging in this way, even if lamination misalignment occurs in the wiring substrate, the first and second high dielectric constant portions can be prevented from deviating from the regions of the first and second wirings, and good durability can be achieved. noise performance can be maintained.

In the present invention, the first high dielectric constant part is arranged in a non-contact state with the second wiring and the second high dielectric constant part, respectively, and the second high dielectric constant part is arranged between the first wiring and the second high dielectric constant part. It may be arranged in a non-contact state with each of the first high dielectric constant portions. With such a structure, it is possible to effectively prevent the occurrence of gaps caused by insufficient filling, which is a problem in the high dielectric constant portion that penetrates the insulating layer and contacts both the first and second wirings.

In the present invention, the first high dielectric constant portion covers the other wiring adjacent to the first wiring in the first conductor layer in addition to the first wiring, and the second high dielectric constant portion covers the first wiring. In addition to the second wiring, the second conductor layer may cover another wiring adjacent to the second wiring. Such a structure can further suppress the influence of noise generated between the first and second wirings and other wirings within the same conductor layer.

In the present invention, various types of wiring can be used as the first and second wirings, but it is desirable that at least one of them is a signal wiring. For example, one of the first and second wirings can be a signal wiring and the other can be a ground wiring. Alternatively, the first and second wirings may be two different signal wirings.

According to the present invention, in the wiring board, by forming a pair of high dielectric constant portions respectively covering a pair of wirings facing each other in the thickness direction with a predetermined insulating layer interposed therebetween, It is possible to avoid problems caused by insufficient filling of the high dielectric constant portion and lamination misalignment, and to reliably suppress the influence of noise due to high frequency signals.

1 is a diagram showing a schematic cross-sectional structure of a wiring board according to an embodiment to which the present invention is applied; FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a manufacturing process from preparing a ceramic green sheet to forming a conductor layer in an outline of a method for manufacturing a wiring board according to the present embodiment; FIG. 3 is a diagram showing manufacturing steps up to the completion of the wiring board of the present embodiment following FIG. 2 in the outline of the method of manufacturing the wiring board of the present embodiment; This is a first comparative example for explaining the effects obtained with the wiring board having the structure shown in FIG. 1 in this embodiment. This is a second comparative example for explaining the effects obtained with the wiring board having the structure shown in FIG. 1 in this embodiment.

A preferred embodiment of a wiring board to which the present invention is applied will be described below with reference to the drawings. However, the embodiment described below is an example of a form embodying the technical idea of the present invention, and the present invention is not limited by the content of this embodiment.

FIG. 1 is a diagram showing a schematic cross-sectional structure of a wiring board according to one embodiment to which the present invention is applied. The wiring board shown in FIG. 1 is a multilayer wiring board in which insulating layers and conductor layers are alternately laminated. Specifically, conductor layer 20, insulating layer 10, conductor layer 21 (first conductor layer of the present invention), insulating layer 11 (predetermined conductor layer of the present invention), and conductor layer 22 are laminated in order from the bottom. (second conductor layer of the present invention), an insulating layer 12 and a conductor layer 23 . In addition, the wiring 30 (first wiring of the present invention) included in the second conductor layer 21, the wiring 31 (second wiring of the present invention) included in the third conductor layer 22, and the respective conductor layers 20 to 23, respectively, a high dielectric constant portion 50 (first high dielectric constant portion of the present invention) covering the wiring 30 on the lower side, and a high dielectric constant portion covering the wiring 31 on the upper side. A dielectric constant portion 51 (second high dielectric constant portion of the present invention) is formed.

The three insulating layers 10 to 12 are formed using a dielectric material such as ceramic, for example, and have a predetermined dielectric constant. The conductor layers 20-23 are formed on the surfaces of the insulating layers 10-12, respectively, using a conductive material such as copper. Among them, the conductor layer 20 is arranged on the lower surface of the lower insulating layer 10, the conductor layer 23 is arranged on the upper surface of the upper insulating layer, and the conductor layers 20 and 23 are exposed on both surfaces of the wiring board. A conductor layer 21 is arranged between the insulating layers 10 and 11 , and a conductor layer 22 is arranged between the insulating layers 11 and 12 . Via conductors 40 to 42 are formed by filling via holes opened in each insulating layer 10 to 12 with a conductive material. Conductor 41 electrically connects conductor layers 21 and 22 , and via conductor 42 electrically connects conductor layers 22 and 23 .

The wiring 30 described above is formed in the center of the conductor layer 21 below the insulating layer 11, and another wiring 32 separated from the wiring 30 is formed around it. Similarly, in the conductor layer 22 on the upper side of the insulating layer 11, the wiring 31 described above is formed in the center, and another wiring 33 separated from the wiring 31 is formed around it. As shown in FIG. 1, the pair of wirings 30 and 31 vertically face each other at the same position when viewed from above in the thickness direction of the wiring board. The pair of wirings 30 and 31 can be of various types, but for example, one can be a signal wiring and the other can be a ground wiring. Alternatively, the pair of wirings 30 and 31 can be, for example, two different signal wirings.

The upper and side surfaces of the lower wiring 30 are covered with the high dielectric constant portion 50 . Similarly, the wiring 31 on the upper side is covered with a high dielectric constant portion 51 on its lower surface and side surfaces. These high dielectric constant portions 50 and 51 are formed using a dielectric material having a dielectric constant higher than that of the insulating layers 10-12. As shown in FIG. 1, the high dielectric constant portions 50 and 51 are vertically opposed at the same position in a plan view viewed from the thickness direction of the wiring substrate, similarly to the wirings 30 and 31, and include the wirings 30 and 31. spread over the area to In addition, the structure is such that the central region of the insulating layer 11 is interposed between the pair of high dielectric constant portions 50 and 51 facing each other vertically. Therefore, the pair of wirings 30 and 31 are arranged to face each other in the thickness direction with the high dielectric constant portion 50, the insulating layer 11, and the high dielectric constant portion 51 interposed in order from the bottom.

Here, the lower high dielectric constant portion 50 is arranged in a wider range than the wiring 30 in plan view in the thickness direction of the wiring board, and in addition to the wiring 30 in the center of the conductor layer 21, It covers the top surface and side surface of part of the other wiring 32 . Similarly, the high dielectric constant portion 51 on the upper side is arranged in a wider range than the wiring 31 in plan view in the thickness direction of the wiring board, and in addition to the wiring 31 in the center of the conductor layer 22, covers part of the lower surface and side surface of the wiring 33 of the . In other words, in the conductor layer 21, the high dielectric constant portion 50 is interposed between the wiring 30 and the other wiring 32 adjacent to each other, and in the conductor layer 22, the wiring 31 and the other wiring 33 adjacent to each other are interposed. A high dielectric constant portion 51 is interposed between them.

In the wiring substrate of FIG. 1, the role of the high dielectric constant portions 50 and 51 is to suppress noise in the wirings 30 and 31 based on high frequency signals. For example, when one of the wirings 30 and 31 is a signal wiring and the other is a ground wiring, the high dielectric constant portions 50 and 51 between the wirings 30 and 31 strengthen the coupling between the signal wiring and the ground wiring, The influence of noise from the signal wiring is reduced, and unnecessary radiation noise from the signal wiring is reduced. Further, when the wirings 30 and 31 are signal wirings different from each other, the high dielectric constant portions 50 and 51 reduce mutual crosstalk noise and unwanted radiation noise. The effects of the high dielectric constant portions 50 and 51 of the present embodiment related to the manufacturing process of the wiring board will be described later.

Although the dielectric constant of the high dielectric constant portions 50 and 51 is not particularly limited, for example, when a dielectric material having a dielectric constant of about 6 is used as the insulating layers 10 to 12, the dielectric constant of the high dielectric constant portions 50 and 51 is About 10 to 20 dielectric materials can be used. In this case, since the insulating layer 11 is interposed between the wirings 30 and 31 in addition to the high dielectric constant portions 50 and 51, the substantial dielectric constant between the wirings 30 and 31 is It is slightly lower than the dielectric constant of 51. At this time, the substantial dielectric constant changes according to the relative thicknesses of the high dielectric constant portions 50 and 51 and the insulating layer 11 therebetween. In any case, if the substantial dielectric constant between the wirings 30 and 31 can be made sufficiently high, the aforementioned effect of suppressing noise can be enhanced.

It should be noted that the cross-sectional structure of FIG. 1 is merely an example when applying the present invention, and there are actually various modifications to which the present invention is applied. For example, in FIG. 1, the pair of wirings 30 and 31 have the same size and shape in plan view, but they may differ in size and shape to some extent as long as they are actually opposed to each other in the thickness direction. . The pair of high dielectric constant portions 50 and 51 are not limited to the same size and shape, and may have different sizes and shapes as long as they cover the wirings 30 and 31 . Also, the high dielectric constant portions 50 and 51 may have a structure that does not cover the wirings 32 and 33 other than the wirings 30 and 31, or may have a structure that covers a larger number of other wirings. Furthermore, although the pair of high dielectric constant portions 50 and 51 are not in contact with each other in the structural example of FIG.

Next, the outline of the method for manufacturing the wiring board of this embodiment will be described with reference to FIGS. 2 and 3. FIG. Here, a manufacturing process for manufacturing a wiring substrate having the structure shown in FIG. 1 will be exemplified. First, three ceramic green sheets 10a, 11a, 12a made of a predetermined ceramic material to be used as the three insulating layers 10 to 12 are prepared. A plurality of via holes 40a, 41a and 42a are opened by punching at predetermined positions of 12a. The positions and number of the via holes 40a to 42a in the ceramic green sheets 10a to 12a can be freely set.

Next, as shown in FIG. 2B, a plurality of via holes 40a to 42a opened in each of the ceramic green sheets 10a to 12a is filled with a conductive paste containing Cu by screen printing. A plurality of via conductors 40, 41, 42 are formed. Subsequently, as shown in FIG. 2(C), a conductive paste containing Cu is applied to both surfaces of the lower ceramic green sheet 10a by screen printing to form conductor layers 20 and 21, respectively. . Similarly, conductor layers 22 and 23 are formed by applying a conductive paste containing Cu to both surfaces of the upper ceramic green sheet 12a by screen printing. At this time, in the conductor layers 21 and 22, as described above, a pair of wirings 30 and 31 are formed in the center and other wirings 32 and 33 are formed around them.

Next, as shown in FIG. 3A, a predetermined ceramic paste is applied by screen printing so as to cover the wiring 30 of the conductor layer 21 and part of the wiring 32 therearound, thereby forming a high dielectric constant portion. form 50; Similarly, the high dielectric constant portion 51 is formed by applying a predetermined ceramic paste by screen printing so as to cover the wiring 31 of the conductor layer 22 and part of the wiring 33 therearound. Then, as shown in FIG. 3(B), the three ceramic green sheets 10a, 11a, 12a in the state of FIG. 3(A) are stacked in this order and then heated and pressed to form a laminate. Thereafter, by degreasing and firing the laminate obtained in FIG. 3B, the wiring board of the present embodiment is completed as described above with reference to FIG.

Hereinafter, in the present embodiment, the effects obtained by the wiring substrate manufactured as described above having the structure shown in FIG. 1 will be described in comparison with FIGS. 4 and 5. FIG. FIG. 4 is a first comparative example showing a partial cross-sectional structure of a wiring board manufactured by a conventional method. In the first comparative example, a conductor layer 70 is formed between two insulating layers 60 and 61 made of ceramic green sheets, and the central wiring 80 of the conductor layer 70 and the upper wiring 81 of the insulating layer 61 are thick. One high dielectric constant portion 90 is arranged between a pair of wirings 80 and 81 facing each other in the direction.

Here, the high dielectric constant portion 90 in FIG. 4 is formed by filling a hole formed in the ceramic green sheet that becomes the insulating layer 61 with a high dielectric constant material. In this case, after forming the high dielectric constant portion 90 on the ceramic green sheet, a pair of wirings 80 and 81 are formed, and the ceramic green sheets to be the insulating layer 60 are laminated and fired to fabricate the wiring board. Therefore, as shown in FIG. 4, the high dielectric constant portion 90 may be inadequately filled, and a gap 90a may be generated between the high dielectric constant portion 90 and the upper and lower wirings 80 and 81 . Since the gap 90a has a dielectric constant substantially equal to that of air, it acts to reduce the effective dielectric constant between the pair of wirings 80 and 81, resulting in deterioration of noise suppression performance due to high-frequency signals. It is a factor that makes

Also, FIG. 5 is a second comparative example showing a partial cross-sectional structure of a wiring board manufactured by a conventional method. In the second comparative example, lamination misalignment occurs when two layers of ceramic green sheets forming the two layers of insulating layers 60 and 61 are laminated, resulting in a state in which the upper and lower wirings 80 and 81 are displaced from each other. ing. As a result, part of the surface of the wiring 80 on the lower side is not covered with the high dielectric constant portion 90 formed in the insulating layer 61, so that it is susceptible to noise due to high frequency signals.

On the other hand, since the wiring board of the present embodiment has a cross-sectional structure as shown in FIG. 1, the problem caused by insufficient filling as shown in FIG. Both can be avoided. That is, since the two high dielectric constant portions 50 and 51 and the insulating layer 11 are sandwiched between the wirings 30 and 31, there is no gap above and below one high dielectric constant portion. Since the high dielectric constant portions 50 and 51 are arranged in a wide area including the wirings 30 and 31 and their surroundings in a plan view from the top, the wirings 30 and 30 are protected by the high dielectric constant portions 50 and 51 even if lamination misalignment occurs. 31 can be avoided from being uncovered. As described above, the structure of the wiring board according to the present embodiment can reliably prevent deterioration of noise suppression performance caused by problems during fabrication.

Although the content of the present invention has been specifically described above based on the present embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the material of the wiring board, the number of insulating layers and conductor layers, the structure of the conductor pattern, and the like can be changed as appropriate as long as the effects of the present invention can be obtained. Further, the individual steps of the wiring board manufacturing method are not limited to the explanation using FIGS. Furthermore, the content of the present invention is not limited by the above-described embodiment with respect to other points, and as long as the effects of the present invention can be obtained, the content disclosed in the above-described embodiment is not limited and can be changed as appropriate. It is possible.

10, 11, 12... insulating layers 20, 21, 22, 23... conductor layers 30, 31, 32, 33... wirings 40, 41, 42... via conductors 50, 51... high dielectric constant portions

Claims (5)

a first conductor layer having a first wiring; a predetermined insulating layer laminated on the first conductor layer; A wiring board comprising a second conductor layer having two wirings,
a first high dielectric constant portion having a dielectric constant higher than that of the predetermined insulating layer and covering at least the first wiring on the predetermined insulating layer side;
a second high dielectric constant portion having a dielectric constant higher than that of the predetermined insulating layer and covering at least the second wiring on the predetermined insulating layer side;
with
The first wiring and the second wiring are arranged to face each other in the thickness direction with the first high dielectric constant portion, the predetermined insulating layer, and the second high dielectric constant portion interposed therebetween. is,
The first high dielectric constant portion is arranged in a region including the first wiring in plan view in the thickness direction , and faces the predetermined insulating layer of the first wiring. covering the side face and sides ,
The second high dielectric constant portion is arranged in a region including the second wiring in plan view in the thickness direction , and faces the predetermined insulating layer of the second wiring. covering the side faces and sides ,
A wiring board characterized by: the first high dielectric constant portion is arranged in a non-contact state with each of the second wiring and the second high dielectric constant portion;
The second high dielectric constant portion is arranged in a non-contact state with each of the first wiring and the first high dielectric constant portion,
The wiring board according to claim 1 , characterized in that: the first high dielectric constant portion covers, in addition to the first wiring, another wiring adjacent to the first wiring in the first conductor layer;
The second high dielectric constant portion covers, in addition to the second wiring, another wiring adjacent to the second wiring in the second conductor layer,
3. The wiring board according to claim 1 , wherein: 4. The wiring board according to claim 1, wherein at least one of said first and second wirings is a signal wiring. 5. The wiring board according to claim 4 , wherein one of said first and second wirings is a signal wiring and the other is a ground wiring.

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