JPH0951208A - Multi-layer board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a multi-layer board in which the change in a characteristic impedance caused by micro via-holes is reduced. SOLUTION: In the multi-layer board 10 in plural layers of which a strip line or a microstrip line is formed, the width of a conductor path in micro via-holes 121, 131 used to interconnect signal lines 21, 22 formed in different layers, that is, the circumferential length of each of the micro via-holes 121, 131 is formed nearly equal to a width (w) of the signal lines 21, 22. Thus, the characteristic impedance of the micro via-holes 121, 131 is made almost equal to the characteristic impedance of the signal lines 21, 22 so as to improve the transmission and reflection characteristic of a signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer substrate, and more particularly to improvement of a multilayer substrate in which strip lines or microstrip lines are formed in a plurality of layers.

[0002]

2. Description of the Related Art Conventionally, electric circuits for processing high frequency signals are often constructed using a multilayer substrate. Further, as the signal line, a strip line or a microstrip line in which the width of the signal line is set so as to have a characteristic impedance corresponding to the frequency of the signal is used, and the strip line or the microstrip formed on different layers of the multilayer substrate is used. The signal lines of the strip line are connected via micro via holes.

[0003]

However, in the above-mentioned conventional multilayer substrate, the size and the number of the micro via holes for connecting the signal lines are different depending on the design of the multilayer substrate, and the ground conductor and The ground conductor corresponding to the micro via hole connecting the paired signal lines was not provided. For this reason, there has been a problem that the characteristic impedance changes in the micro via hole portion and the signal transmission / reflection characteristics deteriorate.

In view of the above problems, it is an object of the present invention to provide a multilayer substrate which can reduce the change in characteristic impedance due to microvia holes.

[0005]

In order to achieve the above-mentioned object, the present invention provides a strip line or a microstrip line in a plurality of layers, and between the signal lines of the lines in different layers. In the multi-layer substrate in which the micro via hole for connecting to each other is formed, the width of the conductive path in the micro via hole is approximately equal to the width of the signal line or wider than the width of the signal line.

According to the multilayer substrate, the width of the conductive path in the micro via hole is formed to be substantially equal to or wider than the width of the signal line. For example, when the signal lines are connected by one micro via hole, the circumference of the micro via hole is formed to be substantially equal to or wider than the width of the signal line. When connecting the signal lines by two or more micro via holes, the total length of the peripheries of the individual micro via holes is formed to be substantially equal to or wider than the width of the signal lines. Here, for example, in a high-frequency signal, the signal current flows near the surface of the conductor due to the skin effect, and the characteristic impedance of the strip line or the microstrip line is greatly influenced by the line width of the signal line, and the same applies to the micro via hole. Become. Therefore, by setting the perimeter of the micro via hole to be approximately equal to or wider than the line width of the signal line,
It is possible to reduce the difference in high frequency resistance and the like between the signal line and the micro via hole. As a result, the characteristic impedance in the micro via hole is brought close to the characteristic impedance in the strip line or the micro strip line formed in each layer.

Further, according to a second aspect of the present invention, a strip line or a microstrip line composed of a ground conductor and a signal line is formed in a plurality of layers, and a signal microvia hole for connecting the signal lines of the lines in different layers. In the multi-layered substrate in which is formed a grounding micro via hole connected to a grounding conductor corresponding to the signal line in the vicinity of the signal micro via hole, corresponding to the signal micro via hole. To propose.

According to the multilayer substrate, the grounding micro via holes connected to the grounding conductors corresponding to the signal lines are provided corresponding to the signal micro via holes connecting between the signal lines formed in different layers. It is provided. This allows
The grounding micro via hole is paired with the signal micro via hole, and the signal micro via is formed in the same manner as the electromagnetic field distribution in the signal line is formed between the grounding conductor corresponding to the signal line. Since the electromagnetic field distribution in the hole is formed between the grounding microvia hole and the grounding microvia hole, the characteristic impedance in the signal microvia hole is brought close to the characteristic impedance in the strip line or the microstrip line formed in each layer.

[0009]

1 is an exploded perspective view showing a multi-layer substrate according to a first embodiment of the present invention. A multi-layer substrate 10 includes five insulating layers made of ceramics having a thickness d of about 0.2 mm. It is formed by stacking layers 11 to 15. further,
On the upper surfaces of the second and fourth insulating layers 12 and 14, signal lines 21 and 22 each made of a printed wiring conductor and having a line width w of, for example, about 0.6 mm are formed, respectively.
Grounding conductors 23 to 25 are formed by printing on the upper surfaces of the insulating layers 11, 13, and 15 almost all over. As a result, the multi-layer substrate 10 in which two strip lines are laminated is formed.

Also, the respective one ends 21a and 22a of the signal lines 21 and 22 are formed so as to overlap with each other, and the micro via holes 121 and 131 formed in the second and third insulating layers are formed.
It is electrically connected through. Here, each of the micro via holes 121 and 131 has a cylindrical shape as shown in FIG. 2, and its diameter D is equal to that of the micro via holes.
The circumference length of 121, 131 is set to about 0.2 mm so as to be equal to the line width w of the signal lines 21, 22.

According to the above structure, the line width w of the signal lines 21 and 22 and the circumference of the micro via holes 121 and 131 are set to be substantially equal to each other, so that the characteristic impedance and the micro via holes in the signal lines 21 and 22 are set. 121,131
And becomes substantially equal to the characteristic impedance at. As a result, the signal transmission / reflection characteristics are improved as compared with the conventional case.

That is, in a high frequency signal, the signal current flows near the surface of the conductor due to the skin effect. Therefore, the characteristic impedance of the strip line is the signal line 2
It is well known that the line width w of 1 and 22 is greatly influenced. Similarly, the micro via holes 121, 131
Also in the above, the signal current flows near the surface of the conductor due to the skin effect. Therefore, the micro via holes 121,131
By setting the length of the circumference of the signal line substantially equal to the line width w of the signal lines 21 and 22, it is possible to reduce the difference in the electromagnetic field environment such as the high frequency resistance between the signal lines 21 and 22 and the micro via holes 121 and 131. So micro via hole
The characteristic impedances at 121 and 131 are set to the signal lines 21 and 2
It can be made substantially equal to the characteristic impedance in 2 and the signal transmission / reflection characteristics can be improved.

Next, a second embodiment of the present invention will be described. FIG. 3 is an exploded perspective view showing the second embodiment.
In the figure, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted. Also, the first
The difference between this embodiment and the second embodiment is that micro via holes 122, 132 for grounding are formed near the micro via holes 121, 131 in parallel with them.

That is, as shown in FIG. 4, the second insulating layer 12
, A micro via hole 122 that is electrically connected to the ground conductors 23 and 24 is formed substantially parallel to the micro via hole 121. Similarly, in the third insulating layer 13, a micro via hole 132 electrically connected to the ground conductor 24 is formed substantially parallel to the micro via hole 131.
Further, the distance t between the outer peripheral surface of the micro via hole 121 and the outer peripheral surface of the micro via hole 122, and the distance between the outer peripheral surface of the micro via hole 131 and the outer peripheral surface of the micro via hole 132 are the same as those of the insulating layers 11 to 15, respectively. It is set to be equal to the thickness d.

According to the above-described structure, the micro via holes 122 and 132 are paired with the micro via holes 121 and 131, respectively, and the electromagnetic field distribution in the signal lines 21 and 22 corresponds to the signal lines 21 and 22. Micro via holes 121,131 as well as formed between
The electromagnetic field distribution in each of the
Since it is formed between the micro via holes 121 and 131, the characteristic impedance in the micro via holes 121 and 131 is the strip formed by the signal lines 21 and 22 and the ground conductors 23 to 25 formed in the second and fourth insulating layers 12 and 14. It is almost equal to the characteristic impedance of the line. Therefore, by providing the grounding microvia holes 122 and 132 paired with the signal microvia holes 121 and 131, it is possible to reduce the change in the characteristic impedance in the microvia holes 121 and 131 and improve the signal transmission / reflection characteristics. it can.

In the first and second embodiments, the micro via holes 121, 122, 131, 132 have a cylindrical shape, but the shape is not limited to this. For example, it may have a long hole shape as shown in FIG. 5, or as shown in FIG.
The shape may be one in which two cylinders are connected in the lateral direction, or substantially the same effect can be obtained by forming the micro via hole 121 wider than the width of the signal line 21 as shown in FIG.

Further, in the second embodiment, the circumference length of the micro via holes 121 and 131 is set to be equal to the line width w of the signal lines 21 and 22, and the micro via holes 122 and 132 for grounding are provided. , The shape of the micro via holes 121, 131 for signals is arbitrary as in the conventional case,
Even if the micro via holes 122 and 132 for grounding are provided, the change in the characteristic impedance in the micro via holes 121 and 131 can be reduced and the signal transmission / reflection characteristics can be improved.

Next, a third embodiment of the present invention will be described. FIG. 8 is a plan view showing the third embodiment. In the figure, the same components as those of the above-described second embodiment are denoted by the same reference numerals, and description thereof will be omitted. The difference between the second embodiment and the third embodiment is that the width of the grounding microvia holes 122, 132 is formed wider than the width of the microvia holes 121, 131 of the signal line 21.

With this structure as well, the micro via holes 122 and 132 are paired with the micro via holes 121 and 131, respectively, and the electromagnetic field distributions in the signal lines 21 and 22 are connected to the ground conductors 23 and 24 corresponding to the signal lines 21 and 22. The electromagnetic field distribution in each of the micro via holes 121 and 131 is similar to that formed between the micro via holes 12 and 131.
Formed between 2,132, so micro via hole 1
The characteristic impedance of 21,131 is substantially equal to the characteristic impedance of the strip line formed by the signal lines 21 and 22 and the ground conductors 23 to 25 formed on the second and fourth insulating layers 12 and 14.

Therefore, by providing the grounding microvia holes 122 and 132 as described above, the change in the characteristic impedance in the microvia holes 121 and 131 can be reduced, and the signal transmission / reflection characteristics can be improved.

Next, a fourth embodiment of the present invention will be described. FIG. 9 is a plan view showing the fourth embodiment. In the figure, the same components as those of the above-described second embodiment are denoted by the same reference numerals, and description thereof will be omitted. The difference between the second embodiment and the fourth embodiment is that the grounding microvia holes 122 and 132 are formed so as to surround the microvia holes 121 and 131 of the signal line 21.

Also according to this structure, the micro via holes 122 and 132 are paired with the micro via holes 121 and 131, respectively, and the electromagnetic field distributions in the signal lines 21 and 22 form the ground conductors 23 and 24 corresponding to the signal lines 21 and 22. The electromagnetic field distribution in each of the micro via holes 121 and 131 is similar to that formed between the micro via holes 12 and 131.
Formed between 2,132, so micro via hole 1
The characteristic impedance of 21,131 is substantially equal to the characteristic impedance of the strip line formed by the signal lines 21 and 22 and the ground conductors 23 to 25 formed on the second and fourth insulating layers 12 and 14.

Therefore, by providing the grounding microvia holes 122 and 132 as described above, the change in the characteristic impedance in the microvia holes 121 and 131 can be reduced, and the signal transmission / reflection characteristics can be improved.

Next, a fifth embodiment of the present invention will be described. FIG. 10 is a plan view showing the fifth embodiment. In the figure, the same components as those of the above-described second embodiment are denoted by the same reference numerals, and description thereof will be omitted. Further, the difference between the second embodiment and the fifth embodiment is that a plurality of grounding microvia holes 122a to 122c, 132a to 132c are formed so as to surround the microvia holes 121 and 131 of the signal line 21. It is in.

Also with this configuration, the electromagnetic field distribution in the signal lines 21 and 22 is formed between the ground conductors 23 and 24 corresponding to the signal lines 21 and 22, as well as the electromagnetic fields in the micro via holes 121 and 131, respectively. Since the field distribution is formed between the micro via holes 122a to 122c and 132a to 132c, the characteristic impedance in the micro via holes 121 and 131 is equal to the second and fourth insulating layers 12 and 1.
Signal lines 21 and 22 and the ground conductors 23 to 2 formed in 4
It is assumed to be substantially equal to the characteristic impedance in the strip line constituted by 5.

Therefore, by providing the grounding microvia holes 122a to 122c and 132a to 132c as described above, it is possible to reduce the change in the characteristic impedance in the microvia holes 121 and 131 and improve the signal transmission / reflection characteristics. be able to.

Next, a sixth embodiment of the present invention will be described. FIG. 11 is a plan view showing the sixth embodiment. In the figure, the same components as those of the above-described second embodiment are denoted by the same reference numerals, and description thereof will be omitted. Further, the difference between the second embodiment and the sixth embodiment is that the micro via holes 122, 132 wider than the width of the signal line 21 are formed, and the ground micro via holes 122, 132 having a width corresponding to this are formed. It is in the point where it was formed.

With this structure as well, the micro via holes 122 and 132 are paired with the micro via holes 121 and 131, respectively, and the electromagnetic field distribution in the signal lines 21 and 22 and the ground conductors 23 and 24 corresponding to the signal lines 21 and 22 are formed. The electromagnetic field distribution in each of the micro via holes 121 and 131 is similar to that formed between the micro via holes 12 and 131.
Formed between 2,132, so micro via hole 1
The characteristic impedance of 21,131 is substantially equal to the characteristic impedance of the strip line formed by the signal lines 21 and 22 and the ground conductors 23 to 25 formed on the second and fourth insulating layers 12 and 14.

Therefore, by providing the grounding microvia holes 122 and 132 as described above, the change in the characteristic impedance in the microvia holes 121 and 131 can be reduced, and the signal transmission / reflection characteristics can be improved.

[0030]

As described above, according to the first aspect of the present invention, the characteristic impedance in the micro via hole is brought close to the characteristic impedance in the strip line or the micro strip line formed in each layer, so that the signal transmission. -Reflectivity can be improved.

According to the second aspect, the grounding microvia hole is paired with the signaling microvia hole, and the electromagnetic field distribution in the signal line is formed between the grounding conductor and the grounding conductor corresponding to the signal line. Similarly, since the electromagnetic field distribution in the signal micro via hole is formed between the signal micro via hole and the grounding micro via hole, the characteristic impedance in the signal micro via hole is the strip formed on each layer of the multilayer substrate. It has an extremely excellent effect that it can be approximated to the characteristic impedance of the line or the microstrip line and the transmission / reflection characteristics of the signal can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a multilayer substrate according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a main part of the first embodiment.

FIG. 3 is an exploded perspective view showing a multilayer substrate according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a main part of a second embodiment.

FIG. 5 is a view showing another embodiment of a micro via hole shape.

FIG. 6 is a view showing another embodiment of a micro via hole shape.

FIG. 7 is a diagram showing another embodiment of a micro via hole shape.

FIG. 8 is a plan view showing a third embodiment of the present invention.

FIG. 9 is a plan view showing a fourth embodiment of the present invention.

FIG. 10 is a plan view showing a fifth embodiment of the present invention.

FIG. 11 is a plan view showing a sixth embodiment of the present invention.

[Explanation of symbols]

10 ... Multilayer substrate, 11-15 ... Insulating layer, 21, 22 ... Signal line, 23-25 ... Grounding conductor, 121, 122, 122a-122c, 1
31,132,132a to 132c… Micro via holes.

Claims (2)

[Claims] 1. A multi-layer substrate in which strip lines or microstrip lines are formed in a plurality of layers, and micro via holes for connecting signal lines of the lines in different layers are formed. A multi-layer substrate characterized in that the width of the path is formed to be substantially equal to or wider than the width of the signal line. 2. A multilayer structure in which a strip line or a microstrip line composed of a ground conductor and a signal line is formed in a plurality of layers, and a signal microvia hole for connecting the signal lines of the lines in different layers is formed. In the substrate, a ground micro via hole connected to a ground conductor corresponding to the signal line is provided in the vicinity of the signal micro via hole, corresponding to the signal micro via hole. .