JPS63239900A - Radio frequency circuit board device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a high-frequency circuit board device in which a circuit board mounted with a printed circuit is housed in a shield case, and particularly relates to a high-frequency circuit board device having a circuit board mounted with a printed circuit and housed in a shield case. Feedthrough capacitors, which are used as electromagnetic shielding elements in
The present invention also relates to a high frequency circuit board that can be formed in a simple process.

(Prior art) A high-frequency circuit board device 2 such as a tuner or a high-frequency modulator is connected to electronic equipment such as audio/video equipment. In order to prevent interference electromagnetic waves from around the circuit and leakage of electromagnetic waves from the circuit itself, the entire circuit board is housed in a shield case, and the input/output terminals are passed through feed-through capacitors installed on the shield case. Place it in such a state that As a result, noise components are guided to the shield case (ground) through the feedthrough capacitor, suppressing noise superimposition on the voltage source and signal.

A commonly used feedthrough capacitor is shown in Figure 7(a).
, (b), it is constructed using a ceramic dielectric body 2 formed into an annular shape having a through hole 1 in the center. The attractant 2 shown in FIG. 7 is, as shown in FIG. 8(a),
Electrodes 3#3 are formed on both sides perpendicular to the through hole 1, and as shown in FIG. Solder the solder according to Step 5. The feedthrough capacitor from which the lead 114 is drawn out is constructed by inserting the lead wire 4 into the side wall of the shield case 6 and soldering or bonding with a conductive adhesive 7, as shown in FIG.

When applied to an actual circuit, it is attached to a shield case 6 as shown in FIG.

FIG. 9 shows a through-hole capacitor configured in a circuit device constructed by housing a thick wire substrate in a shield case 6, and the same parts as in FIG. 8 are given the same reference numerals.

Reference numeral 8 denotes an insulating substrate on which wiring conductors 9 and resistors 10 are formed using thick film technology. A through hole 11 is formed in a predetermined position of the insulating substrate 8, into which the feedthrough capacitor glue tii4 is inserted. The lead 114 of the feedthrough capacitor attached to the shield case 6 as shown in FIG.
It is inserted through the through hole 11 and electrically connected to the wiring conductor 9 by solder 5, and is further mounted through the flat side wall of the shield case facing the side to form a terminal portion 12.

However, since the feedthrough capacitor shown in FIG. 9 protrudes from the shield case 6, it has a defective appearance.

In addition, in the manufacturing process, as shown in FIG. 8, after configuring (installing) the feedthrough capacitor in the shield case 6, as shown in FIG. It becomes a complicated work to connect the wiring conductors.

Also, Fig. 10 is an equivalent circuit of the feedthrough capacitor shown in Fig. 9, and as can be seen from this circuit diagram, the feedthrough capacitor is
Centering on the opposite side of the terminal portion 12, that is, the connection point between the lead wire 4 and the wiring conductor 9, the feedthrough capacitor is separated on one side, and the terminal portion 12 is separated on the other side. Such a structure is not optimal in terms of electromagnetic shielding effect. In other words, the electromagnetic wave shielding effect becomes higher when the feedthrough capacitor is located between the terminal portion 12 and the connection point.

(Problems to be Solved by the Invention) As described above, the conventional feedthrough capacitor formation technology has a structure that does not fully achieve the original purpose (electromagnetic shielding), and the formation process is complicated. There was an inconvenience.

An object of the present invention is to provide a high frequency circuit board device that does not require a special process to form a feedthrough capacitor and has a high electromagnetic shielding effect.

[Structure of the Invention] (Means for Solving Problems) The present invention is constructed by housing a thick film circuit board on which a feedthrough capacitor portion is formed together with a normal bypass capacitor in a shield case.

(Function) According to the present invention, since the feedthrough capacitor section is formed on the side of the substrate housed in the shield case, the connection point between one electrode of the feedthrough capacitor section and the wiring conductor and the connection point of the feedthrough capacitor section and the wiring conductor protrude from the shield case. The terminal section faces each other with the feedthrough capacitor section in between, resulting in a circuit configuration that optimizes the N magnetic wave shielding effect. Further, since the feedthrough capacitor section can be formed simultaneously with other capacitors, no special process is required for forming the feedthrough capacitor.

(Example) The present invention will be described below with reference to an example shown in FIG.

In FIG. 1, (a) shows an insulating substrate 2 such as an alumina substrate.
1, and this insulating substrate 21 is formed with a shaft hole 22 through which a lead wire of a feedthrough capacitor is inserted.

Incidentally, the shaft hole 22 is formed using, for example, a carbon dioxide gas laser beam.

Next, as shown in FIG. 1(b), a silver-palladium paste is applied to both sides of the absolute R substrate 21 by a method such as screen printing. Conductors 23.23- are formed.

Thereafter, as shown in FIG. 1C, a thick film capacitor 1i24.24a is formed using a dielectric paste having a dielectric constant of a.

Here, the wiring conductor 23 constitutes a normal wiring pattern, and the wiring conductor 23' serves as a lower electrode of a single capacitor. Further, the thick film capacitor layers 24, 24 are 1
This is a dielectric layer for a conductive capacitor, and is formed in, for example, a rectangular shape. Note that 24a is a dielectric layer for other capacitors.

The insulating substrate 21 on which the thick film capacitor layer 24.24a is formed in this way is the thick film capacitor layer 24 for feedthrough capacitor.
Wiring conductor 25. as an upper electrode on top of the wiring conductor 25. A wiring conductor 25a, which also serves as an upper electrode, is formed on the thick film capacitor @24a for a normal capacitor (see FIG. 1d).

In this embodiment, the arrangement 1i! shown in FIG. 1(d) above is used. Conductor 25.
At the stage where 25a is formed, firing is performed in an atmosphere of 900'' to 950°.

In addition, in contrast to the absolute 8 substrate 21 in FIG. 1(d), FIG. 1(e)
A resistor 26 is formed as shown in FIG. 2, and fired at 850°C.

FIG. 1(f) shows a completed product of the high-frequency circuit board device according to the present embodiment. As shown in FIG. 1(f), the insulating substrate 21 on which each thick film layer has been formed and fired is used for carrying chip parts, etc. Discrete components 32 are soldered and housed in shield case 27. However, before the insulating substrate 21 is housed in the shield case 27, the lead tQ28 is inserted into the shaft hole 22 and connected to the wiring conductor 23 by solder 29. Further, the lead wire 28 and the AS body 25 are also soldered together as the other electrode of the feedthrough capacitor, and are connected to the shield case 27 by wire rods. A solder connection is made to the conductor 23'. Furthermore, the lead l1128 connects the insulating substrate 21 to the shield case.
When stored in the shield case 27, the terminal protrudes through the terminal protrusion hole 30 formed in the shield case 27, and protrudes to the outside of the case.
The protruding portion constitutes a terminal portion 31.

The high frequency circuit board device according to this embodiment is constructed as described above. In this way, since the feedthrough capacitor can be formed at the same time as other capacitors using thick film technology, the formation process is simplified, and the feedthrough capacitor layer (lower electrode 23', thick film capacitor 1FJ2
4. The upper electrode 25) fits inside the shield case 21 and does not protrude unlike the conventional case.

FIG. 2 is an explanatory diagram for explaining the planar shape of the feedthrough capacitor, and a plurality of feedthrough capacitors are formed assuming an actual high frequency circuit. Note that parts common to those in FIG. 1 are given the same reference numerals. As shown in FIG. 2, in this embodiment, the ring is not cut into an annular shape as in the conventional case, but is formed into a rectangular shape, but it may of course be formed into an annular shape. Incidentally, by using a high dielectric constant base as in this embodiment, the area of the lower electrode 23' is set to 2.01.
111'.

When the planar area of the thick film capacitor layer 24 is 2.411' and the area of the upper electrode 25 is 2.2mm, the capacitance after firing as shown in FIG. 1(d) is 2500 to 3500 P F. Ta.

Further, FIG. 3 shows an equivalent circuit of the present feedthrough capacitor corresponding to FIG. 2. As is clear from comparing this equivalent circuit diagram with the equivalent circuit diagram of FIG. 10, the feedthrough capacitor of FIG. In this case, a feedthrough capacitor is located between the terminal portion 31 and the wiring line 33, and the electromagnetic shielding performance is good.

Further, the mounting area of the feedthrough capacitor according to this embodiment was approximately half or less of that of a conventional capacitor having the same capacity.

FIG. 4 is a sectional view showing another embodiment of the invention. In FIG. 4, the same reference numerals are given to the same members as in FIG.
1 extends from the former capital of Kamidaira of the shield case 27, whereas in this embodiment, the terminal part 31 extends from the shield case 27.
It is designed to extend from the end side. In this case, the lead [141] supports the insulating substrate 21 inside the shield case, and also supports the terminal protruding hole 3 formed on the end side surface.
The portion that will become the terminal portion 31 protrudes from 0. Further, the upper electrode 25 of the feedthrough capacitor section is connected to the lead wire 41 inside the case.
An insulating metal 43 is formed so as not to come into contact with.

The second feature of this embodiment is that the lead $24 is attached to the insulating substrate 21.
1 is not directly connected to the wiring conductor 23' (lower electrode). Therefore, the lead wire 41 is attached to the insulating substrate 21.
There is no need to form a shaft hole for the lead I! to be inserted; instead, the lead I! 41 is connected to the distribution & I cross body 23' so that the solder 42 penetrates into the center of the square.

Incidentally, the upper electrode 25 of the feedthrough capacitor is soldered to the shield case 27 using a wire from the end of the substrate.

FIG. 5 shows the planar shape of the feedthrough capacitor shown in FIG.
The part surrounded by the point iK line is the insulating FI 43.1, and the part surrounded by the dotted chain line is the thick film capacitor layer 24. The dotted line portion shown as these lower members is the lower electrode 23', and the solid line portion is the upper electrode 25.

Further, FIG. 6 shows an equivalent circuit of the feedthrough capacitor shown in FIG. 4, and it can be seen that the circuit structure is similar to that in FIG. 3, and that the electromagnetic shielding effect is enhanced.

[Effects of the Invention] As described above, according to the present invention, the step of forming a through capacitor can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a manufacturing process diagram showing one embodiment of a high frequency circuit board device according to the present invention, FIGS. 2 and 3 are a plan view and an equivalent circuit diagram for explaining the device in FIG. 4 is a sectional view showing another embodiment of the present invention, FIGS. 5 and 6 are a plan view and an equivalent circuit diagram for explaining the device of FIG. 4 in detail, and FIGS. 7 and 821... Insulating substrate, 23, 23", 25... Wiring conductor/body, 24...
Thick film capacitor layer, 21... Shield case, 30... Hole for protruding terminal portion. 31... Lead wire. Agent Patent Attorney Nori Chika Ken Shu
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 (a) (b) Figure 7 Figure 8

Claims (1)

[Claims] A high frequency circuit board device using a thick film substrate on which a normal bypass capacitor is formed, characterized in that a feedthrough capacitor is formed in the process of forming the bypass capacitor.