JPH01168093A - Structure of circuit board - Google Patents

Abstract

PURPOSE:To eliminate impedance mismatching, by forming a grounding layer at the surrounding part of a signal through hole, and providing a coaxial structure. CONSTITUTION:A signal through hole 2 is formed in a circuit board 1 comprising ceramics and the like. A position, whose center is the signal through hole 2, is obtained by the diameter of the signal through hole 2 and the dielectric constant of the material of the circuit board 1. A horseshoe type hole for forming a grounding layer is provided at said position at the surrounding part of the signal through hole 2. A conductor layer is formed on the circuit board 1, on which the signal through hole 2 and the horseshoe type hole are formed by a thick film method, a plating method and the like. A horseshoe type grounding layer 5 is formed in the circuit board 1. Signal patterns 3 such as strip lines, which are connected to the signal through holes 2, are formed on both surfaces of the circuit board 1. Grounding patterns 4 are formed on the surrounding parts of the signal pattern 3 and the signal through hole 2 and the rear surface of the circuit board 1. The horseshoe type grounding layer 5 is connected to the grounding pattern 4. The signal through hole 2 has a coaxial structure.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of a circuit board that has a coaxial structure by forming an annular ground surrounding a signal through hole that conducts in the thickness direction of the circuit board, the ground is connected around the signal through hole. The purpose is to form a coaxial structure in which impedance matching can be performed by forming layers, and to prevent signal reflection due to impedance mismatching. The configuration is such that the ground is formed inside the circuit board.

[Industrial application field]

The present invention relates to the structure of a circuit board in which an annular ground is formed surrounding a signal through hole that conducts in the thickness direction of the circuit board.

In recent years, with the rapid progress of communication devices and the expansion of the range of their use, the frequencies used in these communication devices have also tended to become higher and extend into ultra-high frequency bands.

By the way, the through-holes formed on the circuit board for transmitting high-frequency signals are not structured to perform impedance matching across the thickness of the circuit board, so there is a risk of signal reflection due to impedance mismatching in the through-holes. .

[Conventional technology]

6 and 7 are diagrams for explaining the structure of a conventional circuit board, and FIG. 6 is a perspective view of the main parts of the circuit board.

FIG. 7 is a sectional view taken along line A-A' in FIG.

In the figure, a ground pattern 4.4 and a signal pattern 3.3 are formed on both sides of a circuit board 1 made of fluororesin, ceramic, etc., and the signal patterns 3, 3 on both sides are formed on the inner surface of a signal through hole 2. connected by conductors.

[Problem that the invention seeks to solve]

In the structure of the conventional circuit board mentioned above, the signal pattern has a strip line (or triplate line) and is suitable for high frequencies, but the signal through holes are formed between the thickness of the circuit board and are suitable for high frequencies. Since this structure is not suitable, there is a problem in that signal reflection occurs due to impedance mismatching in this signal through-hole section, which adversely affects high frequency characteristics.

[Means for solving problems]

The present invention solves the above problems and provides a circuit board structure that eliminates impedance mismatching by forming a ground layer around the signal through hole to create a coaxial structure.

In other words, the signal line that conducts in the thickness direction of the circuit board has
This problem is solved by forming an annular ground inside the circuit board surrounding the signal line.

[For production]

The structure of the circuit board as described above makes it possible to eliminate impedance mismatching in the signal through-hole portion by making the signal through-hole of the circuit board coaxial across the thickness of the circuit board.

〔Example〕

1 and 2 are diagrams for explaining one embodiment of the present invention. FIG. 1 is a perspective view of the main part of the circuit board, and FIG.
In the -B' sectional view, the same parts as in FIG. 6 are designated by the same reference numerals.

In the figure, the area around a signal through hole 2 formed in a circuit board 1 made of ceramic or the like is determined from the diameter of the signal through hole 2 and the dielectric constant of the material of the circuit board 1, as shown in FIG. A horseshoe-shaped hole for forming a ground layer is provided in a green sheet at a position centered on the signal through-hole 2, and a thick film method or plating method is applied to the signal through-hole 2 and the circuit board 1 on which the horseshoe-shaped hole is formed. A signal pattern 3 such as a strip line connected to the signal through-hole 2 is formed on both sides of the circuit board l on which a conductive layer is formed and a horseshoe-shaped ground layer 5 is formed. Around through hole 2 and circuit board 1
A ground pattern 4 is formed on the back surface of the ground pattern 4, the horseshoe-shaped ground layer 5 is connected to the ground pattern 4, and the signal through hole 2 has a coaxial structure.

FIG. 3 is a perspective view of essential parts for explaining another embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals.

A signal through hole 2 is formed around a signal through hole 2 formed in a circuit board 1 made of ceramic or the like, as determined from the diameter of the signal through hole 2 and the dielectric constant of the material of the circuit board 1, as shown in the figure. A plurality of holes for forming a ground layer are provided in the form of a green sheet at the center position, and a conductive layer is formed by a thick film method, plating method, etc. on the circuit board 1 on which the signal through hole 2 and the horseshoe-shaped hole are formed. On the surface of the circuit board 1 on which the horseshoe-shaped ground layer 6 is formed,
A signal pattern 3 such as a strip line connected to the signal through hole 2 is formed, a ground pattern 4 is formed around the signal pattern 3 and the signal through hole 2, and on the back side of the circuit board 1, and the horseshoe-shaped arrangement ground The layer 5 is connected to the ground pattern 4, and the signal through hole 2 has a coaxial structure.

4 and 5 are diagrams for explaining other embodiments of the present invention, in which FIG. 4 is a perspective view of essential parts of a multilayer board, and FIG. 5 is a sectional view taken along line c-c' in FIG. Parts equivalent to those in FIG. 1 are given the same reference numerals.

FIG. 4 shows that a plurality of green sheets are laminated and placed around the signal via hole 2' of the multilayer board 7, as shown in FIG.
A circuit board 7 is provided with a plurality of holes arranged in a circle in a green sheet state, and a plurality of holes are formed around the signal via hole 2' and the signal via hole 2'. If the conductor layer is formed by a thick film method or a plating method, a circular ground layer 8 will be formed around the signal through hole 2'. A signal through hole 2 is provided on the surface of this multilayer board 7.
A signal pattern 3 such as a strip line connected to the signal pattern 3 is formed, and a ground pattern 4 is formed around the signal pattern 3 and the signal via hole 2' and on the back side of the multilayer board 7, and the circular ground N8 is connected to the ground pattern. 4, and the signal via hole 2' has a coaxial structure.

By doing so, the signal through hole 2 and the signal via hole 2' have a coaxial structure, and impedance mismatching in the signal through hole 2 and the signal via hole 2' can be eliminated.

The ground conductor of the present invention is not limited to a horseshoe shape, but includes a ring-shaped ground conductor that is continuous inside the board and is referred to as a ring-shaped ground conductor.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the signal through-hole part has a coaxial structure that allows impedance matching, which eliminates impedance mismatching, prevents signal reflection, and improves high frequency characteristics. Extremely effective.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining one embodiment of the present invention, in which FIG. 1 is a perspective view of the main parts of a circuit board, and FIG. 2 is a B of FIG. 1.
-B' sectional view; Figure 3 is a perspective view of main parts for explaining another embodiment of the present invention; Figures 4 and 5 are diagrams for explaining other embodiments of the present invention; The figure is a perspective view of the main parts of the circuit board, FIG. 5 is a sectional view taken along line c-c' in FIG. 4, FIGS. 6 and 7 are diagrams for explaining the structure of a conventional circuit board, and FIG. 2 is a perspective view of essential parts of a circuit board. FIG. 7 is a sectional view taken along line AA' in FIG. In the figure, 1 is a circuit board, 2 is a signal through hole,
2' is a signal via hole, 3 is a signal pattern, 4 is a ground pattern, 5 is a horseshoe-shaped ground layer, 6 is a horseshoe-shaped arranged ground layer, 7 is a multilayer substrate, and 8 is a circular ground layer. Figure 1 Figure 1 tr+B=8'R view Figure 2, l)〒5eJ(,I1=nee,0nlEjltrfJ
if=f'f f! l! ]Figure 3

Claims (1)

[Claims] A circuit board structure characterized in that a signal line conductive in the thickness direction of the circuit board (1) has an annular ground surrounding the signal line formed inside the circuit board (1).