JPH08204341A - Printed board built-in type bypass capacitor - Google Patents

Abstract

PURPOSE: To reduce the inductance of a pattern, to effectively ground it and to easily wire a signal pattern by incorporating a bypass capacitor in a printed board. CONSTITUTION: A dielectric 30 is provided between the pattern 3 of the power terminal 2 of an IC 1 mounted on the surface layer of a multilayer printed board and the inner layer ground pattern 11 of the printed board. Thus, the inductance of the pattern is reduced to suppress high frequency noise and necessary signal. In addition, the bypass capacitor of surface mounting is eliminated and the wiring of the signal pattern is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bypass capacitor with a built-in printed circuit board, and more particularly to a bypass capacitor with a built-in printed circuit board for microwave band ICs.

[0002]

2. Description of the Related Art Conventionally, when mounting an IC on a printed circuit board, a bypass capacitor is inserted. That is, it is necessary to insert a bypass capacitor in the power supply terminal of the IC for the purpose of suppressing the mixing of noise and unnecessary signals. Further, it is necessary to insert a bypass capacitor for the purpose of preventing the abnormal oscillation of the IC due to the feedback.

FIG. 5 is a perspective view showing an example of a conventional bypass capacitor mounting method. A power supply pattern 3 is connected to the power supply terminal portion 2 of the IC 1 on the printed circuit board 4 of this figure. Further, a chip capacitor 20 used as a bypass capacitor is connected to the power supply pattern 3, and opposite terminals of the bypass capacitor are connected to the ground pattern 5.

When power is supplied to the IC 1 from the power supply pattern 3, noise and an AC component which is an unnecessary signal are mixed in addition to the DC component. Since the AC component passes through the bypass capacitor 20 and is released to the ground pattern 5, the IC
Only the DC component is supplied to the power supply No. 1.

In FIG. 3, since the bypass capacitor 20 is arranged on the printed circuit board, it has a problem that it occupies a mounting area and increases the number of mounted parts in view of recent high-density mounting. It was In order to solve this problem, for example, a mounting method of a bypass capacitor with a built-in ceramic substrate disclosed in Japanese Patent Laid-Open No. 01-155643 is known. In this mounting method, a bypass capacitor is provided in a ceramic package material of an integrated circuit. It is a method of forming and cannot be applied to existing integrated circuits.

[0006]

In addition to the mounting area and the number of mounting components described above, there are electrical problems. That is, in the conventional mounting method, the distance between the power supply terminal of the IC and the bypass capacitor is always generated. When connecting with a pattern between these, since the inductance is generated in the power supply pattern in proportion to the above distance, at a frequency where the inductance can be ignored, it acts as a bypass capacitor, but in a high frequency band, particularly in a microwave band or higher, Noise and unnecessary signals are not sufficiently suppressed. When mounting the inductance as small as possible, the IC and the bypass capacitor are mounted side by side,
It is conceivable to complicate the signal pattern other than the power source of the IC. As described above, the present invention has been made in view of the mounting problem and the electrical problem that deteriorates the high frequency characteristics. In addition to reliably eliminating the inductance by the power supply pattern, the bypass that does not disturb other signal patterns is provided. It is intended to provide a method for mounting a capacitor.

[0007]

In order to achieve the above object, a power supply terminal pattern of a surface mounted IC of a bypass capacitor with a built-in printed circuit board according to the present invention and an inner layer ground (GND) pattern of a multilayer printed circuit board are provided. In addition, it has a structure including a dielectric.

[0008]

Next, a mounting method of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a mounting method of a bypass capacitor according to the present invention, and FIG. 2 is a sectional view showing an internal structure of a printed circuit board taken along the line AA ′ in FIG.

In FIGS. 1 and 2, the invention is based on a surface layer portion of a multilayer printed circuit board 8 comprising a first layer 6 and a second layer 7, and a first layer.
A blind via through-hole type dielectric 30 is provided between the layer 6 and the layer 6.

The dielectric 30 is provided with a print pattern which is narrowed so as to cover the top and bottom. The board surface layer pattern 3 is a power supply pattern 3 on which the power supply terminal 2 of the surface mount type IC 1 is mounted, and is in contact with the upper portion of the dielectric 30. At this time, the insulating portion 9 in the surface layer portion of the multilayer printed circuit board 8 is cut out in the upper shape of the dielectric 30 so that the dielectric 30 and the power supply pattern 30 are connected.

As a result, the power supply terminal 2 of the surface mount type IC 1 and the installation layer 11 are connected at the shortest distance by the dielectric 30 (bypass capacitor) with a built-in multilayer printed circuit board.

The multi-layer printed board 8 described above is shown as two layers for simplification, but it is needless to say that it is not limited to this. That is, if a brand via through-hole type dielectric is provided on the surface layer of the multilayer printed circuit board 8 and the inner layer closest to the surface layer, the other plurality of inner layers may be exactly the same as a normal multilayer printed circuit board. In addition, it goes without saying that the same structure can be obtained by changing the surface layer to the back surface layer.

Further, although the brand-via through-hole type dielectric is used in this embodiment, it is not limited to this.

For example, as shown in FIG. 3, a printed circuit board 8
The entire first layer is a dielectric layer 10, and the insulating portion 9 is cut out at the portion to be connected to the power supply pattern 3. The dielectric layer 10 is connected to the ground layer 11 and grounded to form a bypass capacitor.

[0015]

As described above, according to the present invention, the inductance due to the power source pattern is reduced by minimizing the distance between the power source terminal of the IC and the bypass capacitor, so that noise of frequencies above the microwave band and unnecessary signals are eliminated. It has the effect of suppressing.

In addition, by incorporating the bypass capacitor in the printed circuit board, there is also an effect that wiring of signal patterns other than the power source can be facilitated.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a bypass capacitor of the present invention.

FIG. 2 is a cross-sectional view showing an internal configuration of the printed circuit board shown in FIG.

FIG. 3 is a perspective view showing a second embodiment of the bypass capacitor of the present invention.

FIG. 4 is a cross-sectional view showing an internal configuration of the printed circuit board shown in FIG.

FIG. 5 is a perspective view showing a configuration of a conventional bypass capacitor.

[Explanation of symbols]

 1 Surface Mount Type IC 2 Power Supply Terminal of IC 3 Power Supply Pattern 4 Printed Circuit Board 5 Ground Pattern 6 First Layer Printed Circuit Board 7 Second Layer Printed Circuit Board 8 Multilayer Printed Circuit Board 9 Insulating Part 10 Dielectric Layer 11 Ground Layer 20 Chip Capacitor 30 Dielectric body

Claims (3)

[Claims] 1. A printed circuit board built-in type wherein a dielectric is provided inside a multilayer printed circuit board, and the dielectric is connected to a power source pattern on the surface of the multilayer printed circuit board and a ground pattern inside the multilayer printed circuit board. Bypass capacitor. 2. The dielectric is formed in a blind via through hole between a front surface layer or a back surface layer of the multilayer printed circuit board and a nearest inner layer, and one of the blind via through holes is formed in the multilayer printed circuit board. 2. The bypass capacitor with a built-in printed circuit board according to claim 1, wherein the bypass capacitor is connected to the power supply pattern of the above, and one of them is connected to the ground pattern of the inner layer. 3. The printed circuit board built-in type bypass capacitor according to claim 1, wherein the dielectric is formed on an inner layer surface of the multilayer printed circuit board.