JP2000286512A - Printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed board of a structure wherein the amount of work and cost of a part are reduced, relating to connection of signal lines of the inside and the outside of a shielding case mounted on a board. SOLUTION: A printed board 16 has a multilayered structure, and on an uppermost layer (1/4 layer) on which a shielding case 1 is mounted and signal patterns 17 and 23 are formed on the inside and the outside of the shielding case 1, capacitors 18 and 19 that are connected to the signal patterns formed on the inside and the outside of the shielding case, respectively, are provided, and printed coils 20 and 21 that are connected to the capacitors provided on the uppermost layer via through-holes 24 and 25 for constituting a filter circuit are formed on a lower layer, and the signal patterns 17 and 23 formed on the inside and the outside of the shielding case 1 are connected to each other via the filter circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a printed circuit board for connecting an external signal line to a circuit on a substrate shielded by metal.

[0002]

2. Description of the Related Art FIG. 5 shows a first example for explaining a signal line connection structure in a conventional printed circuit board. A through capacitor 6 is mounted on a metal shield case 1 mounted on a printed circuit board 7. FIG. An example is shown in which a signal pattern 2 from outside the shield case 1 is connected to a signal pattern 3 inside the shield case 1 via a feedthrough capacitor 6.

[0003] A conventional configuration for connecting a signal line from the outside to a circuit on a substrate shielded by a metal as described above consists of a shield case 1, a signal pattern 2 located outside the shield case 1, and a signal pattern 2 inside the shield case 1. Printed circuit board 7 having signal pattern 3 located, leads 4 and leads 5
And a feedthrough capacitor 6 having The lead 4 of the feedthrough capacitor 6 is connected to the signal pattern 2 by soldering, and the lead 5 is connected to the signal pattern 3 by soldering.

When the feedthrough capacitor 6 is used in the above-described printed circuit board, a hole is formed in the shield case 1 for mounting the feedthrough capacitor 6. At the time of assembling, the work of mounting the feedthrough capacitor 6, the work of soldering the lead 4 of the feedthrough capacitor 6 to the signal pattern 2 from outside the shield case 1, the work of mounting the lead 4 of the feedthrough capacitor 6 and the signal pattern 2 from the outside of the shield case 1. And the soldering of the leads 5 of the feedthrough capacitor 6 and the signal pattern 3 from the inside of the shield case 1 occur, so that the number of processing and assembly steps is increased.

FIG. 6 shows a second example for explaining a conventional signal line connection structure, in which a low-pass filter composed of a capacitor and a coil is used (circuit diagram) without using a feedthrough capacitor. is there. The circuit shown in FIG. 6 includes a low-pass filter 8 having a coil L1 and capacitors C1 and C2, and a low-pass filter 9 having a coil L2 and capacitors C3 and C4. Low-pass filter 8
Is mounted outside the shield case, and the low-pass filter 9 is mounted inside the shield case.

Here, the connection between the points A and B in FIG. 6 is connected, for example, as shown in FIG. That is, the connection structure between the low-pass filter 8 and the low-pass filter 9 is based on the signal pattern 10, the through-hole 13, the signal pattern 11, the through-hole 14, formed on the outside of the shield case 1 on the printed board 15. The connection is made via a signal pattern 12 formed inside the shield case 1. In this connection structure, since the low-pass filters 8 and 9 are provided inside and outside the shield case 1, when there are a plurality of signal lines, the number of parts increases and the parts cost increases.

[0007]

As described above, FIG.
In the conventional example shown in (1), the use of the feedthrough capacitor 6 has a problem that drilling, mounting, and soldering of the shield case 1 occur, which increases the number of processing and assembly steps. Further, in the conventional example shown in FIGS. 6 and 7, since the low-pass filters 8 and 9 are provided inside and outside the shield case 1, when there are a plurality of signal lines, the number of parts increases and the parts cost increases. There was a point.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a method of forming a hole in a shield case by using a feedthrough capacitor to connect the inside of a shield case mounted on a substrate to an external signal line is provided. An object of the present invention is to provide a printed circuit board having a structure capable of preventing an increase in man-hours and assembling man-hours such as wiring and mounting, and reducing component costs.

[0009]

In order to achieve the above object, a printed circuit board according to the present invention has a multilayer structure of a printed circuit board, a shield case is attached, and a signal pattern is formed inside and outside the shield case. The uppermost layer provided with capacitors respectively connected to the signal patterns formed inside and outside the shield case, and the lower layer is connected to the capacitor provided in the uppermost layer through a through hole to form a filter circuit. Are formed, and signal patterns formed inside and outside the shield case are connected via the filter circuit.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The printed circuit board of the present invention uses a capacitor and a printed coil without using a conventional feedthrough capacitor and without providing a filter circuit inside and outside a shield case. It has a signal line connection structure that can configure a circuit and connect an external signal line to a circuit in the shield case.

Embodiment 1 FIG. 1 is a partial sectional view showing a signal line connection structure of a printed circuit board according to the first embodiment. In the printed circuit board shown in FIG.
6, the shield case 1 is attached to the uppermost 1/4 layer, a low-pass filter equivalent to the low-pass filter composed of L3, C5, and C6 in FIG. 2 is formed, and a signal line is connected. .

That is, the printed circuit board according to the first embodiment has four layers (1/4 layer, 2/4 layer, 3/4 layer, 4/4 layer).
), The shield case 1 provided on the uppermost layer, the signal pattern 17 from the outside of the shield case 1, the capacitors 18 and 19, the print coils 20 and 21 formed on the lower layer, and the uppermost layer. It is composed of a signal pattern 23 from inside the shield case 1 and through holes 24, 25, 26, 27 penetrating between layers.

The printed coils 20 and 21 are formed on 2/4 and 3/4 layers of the four-layer printed circuit board 16, and the capacitor 18, the printed coil 20 and the printed coil 2 are formed.
0 and 21 are connected via through holes 24 and 25, respectively. The print coil 21 is connected to the capacitor 19 provided on the uppermost layer via the through hole 26, the signal pattern 22, and the through hole 27.

Here, as shown in FIG. 3, the printed coil has a printed pattern in which square sides are continuous in a spiral shape, and the inductance in this case is
It is determined by equation (1). L = 0.141 × a × n ^5/3 × log (8 × a / c) [μH] (1) Note that a = (Di + Do) / 4, c = (Do−Di) /
2, n: number of turns, Do, Di: lengths of outermost and innermost sides (unit is inch)

In the equation (1), Di = 3 mm, Do =
Assuming that 15 mm and n = 7, the inductance per print coil is 0.497 [μH], so that the total of two print coils is 0.994 [μH].
Becomes Therefore, in the case of the structure shown in FIG.
By configuring the low-pass filter with the individual components and the print coil, connection between the external circuit of the shield case 1 and the circuit in the shield case 1 becomes possible. The change of the inductance is performed by changing the shape of the print coil (D in equation (1)).
i, Do, n) or by combining a plurality of print coils.

Embodiment 2 FIG. 4 shows a signal line connection structure of a printed circuit board according to the second embodiment, in which a four-layer printed circuit board 28 is used, the shield case 1 is attached to the uppermost ４ layer, and the shielding effect is further enhanced. 2 shows a case where the shield case 30 is attached to the 4/4 layer to form a low-pass filter equivalent to the low-pass filter composed of L3, C5, and C6 in FIG.

The second embodiment has four layers (1/4 layer, 2 /
Printed circuit board 2 consisting of 4 layers, 3/4 layers, 4/4 layers)
8, shield case 1, shield case 30, signal pattern 17 from outside shield case 1, capacitor 18
And 19, print coils 20, 21, signal pattern 23 inside shield case, through holes 24, 25,
29.

The printed coils 20 and 21 are located on 2/4 and 3/4 layers of the four-layer printed circuit board. The capacitor 18 and the printed coil 20, and the printed coil 20 and the printed coil 21 pass through through holes 24 and 25, respectively. Connected. The print coil 21 is connected to the capacitor 19 via the through hole 29. The capacitor 18 has a signal pattern 17 from the outside of the shield case 1.
Is connected to the capacitor 19, and a signal pattern 23 to the inside of the shield case is connected to the capacitor 19.

As described above, if a low-pass filter using a printed coil is used, a signal outside the shield case and a signal inside the shield case can be easily connected.

Therefore, according to each of the above embodiments, since the printed coil is used, the component cost of the coil itself is zero. Therefore, the components used for the low-pass filter can be realized with only two capacitors, and the component cost can be reduced. In addition, there is no need to drill holes in the shield case for realizing the feedthrough capacitor, to mount the feedthrough capacitor, and to connect the signal lines, so that the number of processing steps and the number of assembly steps can be reduced.

[0021]

As described above, according to the present invention, the printed circuit board has a multilayer structure, and the shield case is attached to the uppermost layer on which a signal pattern is formed inside and outside the shield case. Since the capacitors connected to the signal patterns formed inside and outside of the device were provided, and the lower layer was connected to the capacitor provided on the uppermost layer via a through hole, the printed coil forming the filter circuit was formed. , Formed inside and outside the shield case via the above filter circuit, without using a feedthrough capacitor, and therefore without the need for drilling the shield case, mounting work of the feedthrough capacitor and connection work of the signal lines. Connected signal patterns can be easily connected, and the cost of parts can be reduced. It is possible to obtain a printed substrate having a structure capable of and.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a signal line connection structure of a printed circuit board according to Embodiment 1 of the present invention.

FIG. 2 is an equivalent circuit diagram showing the filter circuit of FIG.

FIG. 3 is an explanatory diagram showing a pattern of the print coil of FIG. 1;

FIG. 4 is a partial cross-sectional view showing a signal line connection structure of a printed circuit board according to Embodiment 2 of the present invention.

FIG. 5 is an explanatory diagram showing a signal line connection structure of a printed circuit board according to a conventional example.

FIG. 6 is an explanatory view showing a signal line connection structure of a printed circuit board according to another conventional example.

FIG. 7 is an explanatory diagram showing a connection structure between points A and B in FIG. 6;

[Explanation of symbols]

 1,30 Shield case 16,28 Printed circuit board 17 Signal pattern 18,19 Capacitor 20,21 Print coil 22,23 Signal pattern 24,25,26,27 Through hole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E351 BB15 BB19 BB22 BB26 BB31 BB49 GG11 GG20 5E321 AA02 AA32 GG01 GG05 5E338 AA03 BB75 CC01 CC05 CD02 CD17 EE13 EE31 5E346 AA11 AA15 AA60 BB02 H01H20H

Claims (1)

[Claims] 1. A printed circuit board having a multilayer structure, a shield case is attached, and a signal pattern is formed on the inside and outside of the shield case. The signal pattern is formed on the inside and outside of the shield case. Along with the capacitors connected to each other, the lower layer forms a printed coil which forms a filter circuit by being connected to the capacitor provided in the uppermost layer through a through hole, and forms the inside of the shield case and the inside through the filter circuit. A printed circuit board for connecting a signal pattern formed outside.