JPH04296095A - Multilayer circuit board - Google Patents

Abstract

PURPOSE:To enable a coaxial circuit to be surely formed inside a circuit board at a low cost by a method wherein a first coaxial pattern and a second coaxial pattern are shielded by surrounding them with earth patterns of boards. CONSTITUTION:A first coaxial line pattern 33 is formed in line on a first coaxial board 31. An earth pattern 35 is formed on all both the sides of the first coaxial line pattern 33. A second coaxial line pattern 41 is formed in a second coaxial board 39 the same as the first coaxial line pattern 33, and an earth the pattern 35 is formed on both the sides of the first coaxial line pattern 41. An intermediate earth board 43 where the earth pattern 35 is formed is arranged between the first and the second coaxial board, 31 and 39. Outer earth boards 45 and 47 where an earth pattern is provided respectively are arranged outside the first and the second coaxial board, 31 and 39. The earth patterns 35 of the boards 31, 39, 45, and 47 are electrically connected together with a through- hole 37.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer circuit board, and more particularly to a multilayer circuit board in which a coaxial line pattern forming a coaxial circuit is formed within the board.

0002

2. Description of the Related Art Conventionally, in transmission equipment that handles high frequency bands of GHz or higher, for example, as shown in FIG. It is being combined into a signal. That is, in FIG. 5, reference numeral 11 indicates a printed circuit board, and this printed circuit board 11 is formed with a circuit A for inputting a signal a and a circuit B for inputting a signal b.

Circuits A and B each have an input terminal 13, a connection terminal 15, and a coaxial wire 17 arranged on a printed circuit board 11, and signals a and b are arranged on the printed circuit board 11. Connection terminal 15 and coaxial wire 1
7 to the output terminal 19, and this output terminal 19
In the step shown in FIG. 6, the signals are combined into one output signal.

[0004] In such a coaxial circuit, when considering noise, crosstalk, loss, etc., circuit A and circuit B have a completely balanced mounting arrangement and a balanced pattern route. It is desired that

[0005]

[Problems to be Solved by the Invention] However, in such a conventional coaxial circuit, an expensive coaxial wire 17 is used, which increases manufacturing costs.
Since it requires a relatively large space for mounting, it is not suitable for high-density mounting. The present invention has been made to solve these conventional problems, and an object of the present invention is to provide a multilayer circuit board in which a coaxial circuit can be formed within the board at low cost and reliably.

[0006]

[Means for Solving the Problems] The multilayer circuit board of the present invention includes a first coaxial line board on which ground patterns are formed on both sides of a first coaxial line pattern, and a ground pattern formed on both sides of a second coaxial line pattern. an intermediate grounding board on which a grounding pattern is formed is placed between the second coaxial line board and the second coaxial line board, and an outer grounding board is placed outside the first coaxial line board and the second coaxial line board; , the ground patterns of each of the substrates are electrically connected through via holes.

[0007]

In the multilayer circuit board of the present invention, the first coaxial line pattern and the second coaxial line pattern are surrounded and shielded by the ground pattern of each board.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of the present invention will be explained with reference to embodiments shown in the drawings. 1 to 3 show an embodiment of the multilayer circuit board of the present invention. In the figures, reference numeral 31 indicates a first coaxial line board, and this first coaxial line board 31 includes a linear A first coaxial line pattern 33 is formed on.

On both sides of this first coaxial line pattern 33,
A ground pattern 35 is formed on the entire surface, and a large number of via holes 37 are formed at predetermined intervals along the first coaxial line pattern 33 at positions on both sides of the first coaxial line pattern 33 of this ground pattern 35. ing. Reference numeral 39 indicates a second coaxial line board, and this second coaxial line board 3
9 is formed in exactly the same way as the first coaxial line board 31.

That is, the second coaxial line board 39 has a first
The second coaxial line pattern 4 is exactly the same as the coaxial line pattern 33.
1 is formed, ground patterns 35 are formed on both sides of this second coaxial line pattern 41, and via holes 37 are formed on both sides of the second coaxial line pattern 41, just like the first coaxial line board 31. has been done. First coaxial line board 3
1 and the second coaxial line board 39, there is a ground pattern 3
A via hole 37 is formed in the intermediate ground substrate 43 at a position corresponding to the via hole 37 of the first coaxial line substrate 31.

Outside the first coaxial line board 31 and the second coaxial line board 39, outer grounding boards 45 and 47 on which the grounding pattern 35 is formed are disposed, and these outer grounding boards 45 and 47 have the following features: A via hole 37 is formed at a position corresponding to the via hole 37 of the first coaxial line board 31. Then, as shown in FIG.
It is electrically connected by 7.

That is, each substrate 31, 39, 43, 45
, 47 are formed with ground patterns 35 as shown in FIG. In addition, FIG. 3 shows an outline of the multilayer circuit board viewed from the top. In FIG. The line pattern 41 is internally connected to predetermined input and output sections within the multilayer circuit board 51 .

FIG. 4 shows details of the coaxial circuit formed by the first coaxial line pattern 33, the second coaxial line pattern 41, etc., and shows the distance from the top surface of the outer ground board 45 to the center of the intermediate ground board 43. , and outer ground board 4
The distance from the bottom surface of 7 to the center of the intermediate ground board 43 is
Each is rated L. In addition, the first coaxial line pattern 3
3 and the second coaxial line pattern 41 are respectively d.
Furthermore, the distance between the lower surface of the outer ground board 45 and the upper surface of the first coaxial line board 31, and the interval between the lower surface of the outer ground board 45 and the upper surface of the first coaxial line board 31,
The distance between the lower surface of 3 and the upper surface of the second coaxial line board 39 is D, respectively.

In such a coaxial circuit, the impedance Z0 (ohm) can be determined by the following approximate equation. Z0 = [138/(εr)1/2]・log 1
0.{(D+1.5d)/K1 d} Here, εr is the relative dielectric constant, K1 is the internal conductor effective diameter coefficient, and d and D are the dimensions shown in FIG. 4.

In the multilayer circuit board configured as described above, the first coaxial line board 31 has the ground patterns 35 formed on both sides of the first coaxial line pattern 33, and the ground patterns 35 are formed on both sides of the second coaxial line pattern 41. The ground pattern 35 is connected between the ground pattern 35 and the second coaxial line board 39 on which the ground pattern 35 is formed.
An intermediate grounding board 43 is disposed on the outside of the first coaxial line board 31 and the second coaxial line board 39,
The outer ground boards 45 and 47 are arranged, and each board 3
1, 39, 43, 45, 47 earth patterns 35,
Since electrical continuity is achieved through the via hole 37, a coaxial circuit can be formed within the substrate at low cost and reliably.

That is, in the multilayer circuit board configured as described above, the coaxial circuit is formed by the first coaxial line pattern 33 and the second coaxial line pattern 41 without using expensive coaxial wires as in the conventional case. Therefore, it is very cheap. Further, the first coaxial line pattern 33 and the second coaxial line pattern 41 are arranged on each substrate 31, 39, 43, 4.
Since it is surrounded by the ground patterns 35 of No. 5 and 47 and is reliably shielded, it becomes a stable coaxial circuit with no noise, crosstalk, loss, etc.

Furthermore, the circuit formed by the first coaxial line pattern 33 and the circuit formed by the second coaxial line pattern 41 are arranged in a completely balanced manner, and the pattern route is also balanced. This becomes possible easily. Furthermore, since the coaxial circuit is formed within the multilayer circuit board, no special mounting space is required.
This makes it extremely suitable for high-density packaging.

Furthermore, in the multilayer circuit board constructed as described above, by changing the thickness d of the first coaxial line pattern 33 and the second coaxial line pattern 41 and the above-mentioned interval D, the above-mentioned formula can be satisfied. It becomes possible to easily determine impedance based on .

[0019]

As described above, in the multilayer circuit board of the present invention, the first coaxial line board has the ground pattern formed on both sides of the first coaxial line pattern, and the ground pattern is formed on both sides of the second coaxial line pattern. An intermediate grounding board on which a grounding pattern is formed is placed between a second coaxial line board on which a ground pattern is formed, and an outer grounding board is placed on the outside of the first coaxial line board and the second coaxial line board, Furthermore, since the ground patterns of each board are electrically connected through the via holes, there is an advantage that a coaxial circuit can be formed within the board at low cost and reliably.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a multilayer circuit board of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1;

FIG. 3 is a top view schematically showing the multilayer circuit board of FIG. 1;

FIG. 4 is a cross-sectional view showing details of the coaxial circuit of FIG. 2;

FIG. 5 is a perspective view showing a printed circuit board on which a conventional coaxial circuit is formed.

FIG. 6 is an explanatory diagram showing signal synthesis by the coaxial circuit of FIG. 5;

[Explanation of symbols]

31 First coaxial line board 33 First coaxial line pattern 35 Earth pattern 37 Beer hall 39 Second coaxial line board 41 Second coaxial line pattern 43 Intermediate ground board 45, 47 Outer ground board

Claims (1)

[Claims] Claim: 1. Between a first coaxial line substrate in which ground patterns are formed on both sides of a first coaxial line pattern, and a second coaxial line board in which ground patterns are formed on both sides of a second coaxial line pattern, An intermediate grounding board on which a grounding pattern is formed is arranged, and an outer grounding board is arranged outside the first coaxial line board and the second coaxial line board, and further,
A multilayer circuit board characterized in that the ground patterns of each board are electrically connected through via holes.