JPS6344317B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for installing and wiring various electrical components on a printed circuit board to form an electronic circuit, and to prevent the above-mentioned high frequency This invention relates to a connection structure between circuits for eliminating the influence of

For example, in an electronic circuit such as a radiosonde that converts weather elements into frequency signals in response to changes in the weather elements, modulates the frequency or amplitude of a carrier wave with the frequency signal, and transmits the same, the weather elements are converted into frequency signals. Since the low-frequency circuit for conversion and the high-frequency oscillation circuit for sending the carrier wave are generally placed close to each other, the signal sent from the low-frequency oscillation circuit is easily influenced by the carrier wave, and normal transmission of observation data may not be possible. There are some things I can't do.

In order to avoid such a situation, generally a high frequency circuit or a low frequency circuit affected by the high frequency circuit is covered with a shielding case to prevent the emission of unnecessary signals (noise) from the high frequency circuit or the low frequency circuit etc. This prevents unnecessary signals from being mixed in.

When a shielded circuit section (circuit covered by a shield case) is covered with a shield case in this way, the above-mentioned unnecessary signals may be emitted or mixed from the connection path with other circuit sections (circuits not covered with a shield case). Therefore, conventionally, the shielded circuit section and the other circuit section are connected via a feedthrough capacitor. In other words, a feed-through capacitor has a lead wire surrounded by ceramic, and is widely used as a terminal to remove high-frequency noise for transmitting and receiving signals between circuits inside and outside the shield case. A connection structure is adopted in which a connection path between the shielded circuit section and other circuit sections is led out from the printed circuit board by a lead wire and connected to the lead terminal of the feedthrough capacitor.

However, with this conventional connection structure,
Since the mounting position of the feedthrough capacitor is usually set on the side of the shield case, the feedthrough capacitor is fixed at a certain distance from the printed circuit board, and the fixing point of the feedthrough capacitor is Since the printed conductive foil surface of the printed circuit board is no longer at the same potential at high frequencies, the performance of the feedthrough capacitor as a noise removal filter is impaired, and a satisfactory result is not necessarily obtained.

In addition, the lead wires that connect the lead terminals of feed-through capacitors and the connection paths with each circuit section are not only easily affected by high frequencies, but also because the lead wires connect the connection paths of each circuit section and the feed-through capacitors. However, this method requires a lot of wiring work, and the feedthrough capacitor is also expensive.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional drawbacks and provide a connection structure that prevents the emission or incorporation of high frequency noise with a simple structure without using a feedthrough capacitor.

Embodiments of the present invention will be described below with reference to the drawings.
The drawings are for explaining embodiments of the present invention, and FIG. 1A shows the component mounting surface (front surface) of the printed circuit board, and FIG. 1B shows the opposite component mounting surface (back surface) of the printed circuit board. Figure 2 is a perspective view of the shield case, Figure 3 is a plan view of components and shield case mounted on a printed circuit board, and Figure 4 is an enlarged view of the main part of the A-A cross section in Figure 3. The sectional view and FIG. 5 are print pattern diagrams of main parts showing another embodiment.

In FIGS. 1A, B to 5, each symbol is as follows.

1: Printed circuit board 101... Planar conductor, 102... Shield case fixed conductor, 103... Shielded component connection conductor, 104... Component connection conductor, 105... Shielded circuit part wiring conductor, 106... Outgoing wiring conductor, 107... Through hole connection Part, 108... Solder resist, 109... Screw hole, 110... Shield conductor, 111... Base, 112... Notch, A... Shielded circuit part, B... Connection circuit part, C... Other circuit parts 2: Shield case 201... Electrode part, 202... Shield case main body, 203... Fixing part, 204... Screw hole 3: Screws 4 to 6: Component 7: Solder First, the configuration of the printed circuit board 1 will be explained. Incidentally, all the conductors on the printed circuit board surface described below are formed by printed wiring techniques. Figure 1A
As shown in FIG. 1 and B, the printed circuit board 1 is composed of a double-sided printed circuit board, and as shown in FIG. A connection circuit portion B connecting A and C is formed by each printed pattern, and as shown in FIG. 1B, at least the above-mentioned shielded circuit portion A and A shield conductor 110 is formed over the entire surface of the portion corresponding to the connection circuit portion B.

A shielded component connection conductor 103 is formed in the shielded circuit portion A.
Shielded circuit wiring conductor 1 derived from
05 is made of a thin and relatively long conductive foil for the purpose of forming an inductance portion of a high frequency noise removal filter to be described later. Therefore, the wiring conductor 105 is led out to the connection circuit portion B in a detour. For example, four plane conductors 101 are formed in the connection circuit portion B, as many as the number of connections from the shielded circuit portion B to the other circuit portions C, and all the connections between both circuit portions AC are the same. This is done via a planar conductor 101. This planar conductor 101 is formed into a rectangular shape having a size of approximately (15 mm x 10 mm), for example, and constitutes a capacitance portion of a high frequency noise removal filter to be described later.

In addition, screw holes 109 are provided in two places, for example, through the back surface of the connection circuit portion B, in order to bring the electrode portion 201 of the shield case 2, which will be described later, into close contact with the connection circuit portion B.

A component connection conductor 104 is formed in the other circuit portion C that is not shielded, and is connected to the planar conductor 101 by a lead-out wiring conductor 106.

A shield case fixed conductor 102 is formed around the shielded circuit portion A and the connection circuit portion B except for the portion where the lead-out wiring conductor 106 is arranged, and the shield case fixed conductor 102 has through-hole connections 107 everywhere, and the shield conductor 11 on the back side.
It is electrically connected to 0.

In addition, the printed pattern portion of the printed circuit board 1 includes soldered parts (shield case fixed conductor 102, shielded component connection conductor 103,
A solder resist 108 is applied to substantially the entire surface except for the component connection conductor 104), and in particular, the solder resist 108 of the connection circuit portion B constitutes the dielectric of the capacitance portion.

Next, the configuration of the shield case 2 will be described.
The shield case 2 is made of a conductive plate material, and has a volume that covers the shielded circuit portion A of the printed circuit board 1 and includes the components 4 and 5 of the shielded circuit (see FIG. 3), as shown in FIG. A main body 202 and a fixing part 203 formed by extending the hem portion of the main body 202 outward in the plane direction of the printed circuit board 1.
and the electrode section 201 are integrally constructed.

Shield case body 202 of the fixing part 203
The extension length from the shield case fixing conductor 102 of the printed circuit board 1 is set to an appropriate length that allows the shield case 2 to be soldered and fixed, and the area of the electrode part 201 is set to the area formed in the connection circuit part B. The area is set to cover all of the planar conductor 101 and allow its end portion to reach the shield case fixed conductor 102 and be fixed by soldering.

Further, the electrode portion 201 of the shield case 2 is provided with screw holes 204 at two locations corresponding to the screw holes 109 provided in the printed circuit board 1 for closely contacting the electrode portion 201 with the connection circuit portion B.

The shield case 2 is placed on the printed circuit board 1.
The fixed state is shown in FIGS. 3 and 4. That is, after the components 4, 5, and 6 are soldered and connected to predetermined connection conductors 103, 104, the shield case 2 is covered with the main body 202 so that the components 4, 5 constituting the shielded circuit section are included. After the electrode part 201 is closely fixed to the connection circuit part B of the printed circuit board 1 with the screw 3 through the screw hole 204 of the electrode part 201 of the shield case 2 and the screw hole 109 of the printed circuit board 1, the surrounding area and the fixing part 203 are fixed. and the shield case fixing conductor 102 of the printed circuit board 1 are electrically connected to each other by the solder 7 and fixed.

When looking at the connecting circuit portion B in cross section, as shown in FIG.
is sandwiched between the base 111 (for example, a glass epoxy resin plate) of the printed circuit board 1, and the electrode section 201 of the shield case 2 is tightly attached to the upper surface of the solder resist 108 by tightening with the screw 3. ), a shield conductor 110 is attached to the back surface of the base 111, and the shield conductor 1
10 and the electrode part 201 are the through-hole connection part 10
7 and the shield case fixed conductor 102 .

With the above configuration, the connecting circuit part B has the planar conductor 101 as one electrode, the electrode part 201 of the shield case 2 as the other electrode, and the solder resist applied to the printed circuit board 1. A capacitor with 108 as a dielectric and a capacitor with the planar conductor 101 as one electrode, the shield conductor 110 pasted on the back side of the printed circuit board 1 as the other electrode, and the base 111 of the printed circuit board 1 as the dielectric. will be formed, and the 2
In this type of capacitor, one electrode is a planar conductor 101
The other electrode is the shield conductor 110 and the electrode part 201 and is not common, but
They are connected to each other by a through-hole connection portion 107. And the plane conductor 101
The shielded circuit wiring conductor 105 is connected to the shielded circuit, and as described above, high frequency noise is removed between the shielded circuit and other circuits by the inductance of the wiring conductor 105 and the capacitance of the capacitor. A filter is configured.

In addition to the above, a Teflon film, a mica plate, etc. can also be used as the dielectric material, and the use of the solder resist described above is only one embodiment of the present invention. However, when a solder resist is used as the dielectric material, there is an advantage that the step of sandwiching the dielectric material is not required when mounting the shield case 2 on the printed circuit board 1.

In addition, several protrusions are provided in the thickness direction of the printed circuit board from the bottom part of the shield case body 202 and the end of the electrode part 201, and the printed circuit board 1 has through holes corresponding to the protrusions that reach the shield conductor on the back side. If the protrusion is passed through the through hole and soldered to the shield conductor, there is no need to form the shield case fixed conductor 102 and the through-hole connection portion 107 on the printed circuit board 1.

Next, another embodiment of the present invention will be described with reference to FIG. 5 regarding the connection circuit portion B.

That is, in the embodiment, there are several locations on the planar conductor 101, and in the embodiment, there are three locations, and one end is connected to the planar conductor 101.
The effective length of the planar conductor 101 is increased by removing the conductor in a slit shape that reaches the end of the conductor 101 and providing the notch 112. I am trying to configure it as well.

With this configuration, there is no need to configure an inductance portion in the shielded circuit wiring conductor 105 as in the above embodiment, and it is possible to reduce the volume occupied by the shielded circuit due to mounting design, etc. This embodiment is particularly effective.

In the above embodiments, the shielded circuit section and other circuit sections are configured on the same printed circuit board, but the present invention can be applied even if the shielded circuit section and other circuit sections are configured on separate printed circuit boards. It can be implemented. In this case, the connecting circuit portion B is naturally formed on the printed circuit board on which the shielded circuit portion A is formed.

As is clear from the above description with reference to the embodiments, according to the present invention, the connection between the internal and external circuits of the shield case is made using a conductive foil (print pattern) formed on the printed circuit board. Moreover, since the high-frequency noise removal filter installed there is also formed of conductive foil on the printed circuit board surface, the ground potential of the filter can be maintained at the potential of the shielding case even at high frequencies, and the shielding effect, that is, the noise A connection structure can be obtained which has an extremely good effect of preventing release or mixing of .

Further, according to the present invention, since a feed-through capacitor is not required, it is possible to downsize the device and reduce component costs.Moreover, the wiring of the connection circuit is completed by mounting the shield case on the printed circuit board, and the feed-through capacitor is not required. Since wiring to capacitors etc. is not required, it greatly contributes to reducing the wiring man-hour.

As described above, the present invention brings great benefits in terms of both electrical characteristics and device manufacturing, and its effects are extremely large.

[Brief explanation of drawings]

The drawings are for explaining embodiments of the present invention, and FIG. 1A shows the component mounting surface (front surface) of the printed circuit board, and FIG. 1B shows the opposite component mounting surface (back surface) of the printed circuit board. Figure 2 is a perspective view of the shield case, Figure 3 is a plan view of components and shield case mounted on a printed circuit board, and Figure 4 is an enlarged view of the main part of the A-A cross section in Figure 3. The sectional view and FIG. 5 are print pattern diagrams of main parts showing another embodiment. Main symbols: 1: Printed circuit board, 101... Planar conductor, 102... Shield case fixed conductor, 105...
Shielded circuit part wiring conductor, 107... Through-hole connection part, 108... Solder resist, 110... Shield conductor, 111... Base, 112... Notch part,
2: Shield case, 201...electrode part, 202...
Shield case body.

Claims (1)

[Claims] 1. In an apparatus in which a shielded circuit section that requires shielding and other circuit sections that do not require shielding are mounted on a printed board, A planar conductor having a set area is formed in the connection path between the shielded circuit section and other circuit sections, and a planar conductor having a set area is formed on the surface opposite to the component mounting surface at least between the shielded circuit section and the planar conductor. A shield conductor is formed at a corresponding location, and an electrode portion is provided in the shield case that is electrically conductive with the shield case and has an area that covers the planar conductor, and the electrode portion of the shield case and the planar conductor of the printed circuit board are connected. A shielded circuit part characterized in that the shield case is mounted on the printed circuit board by interposing a dielectric between the shield case and the shield conductor of the printed circuit board, and electrically conducting the shield case and the shield conductor of the printed circuit board. Connection structure with circuit section. 2. A connection structure between a shielded circuit section and other circuit sections according to claim 1, characterized in that the dielectric is formed of a solder resist coated on a planar conductor. 3. A connection structure between the shielded circuit section and other circuit sections as set forth in claim 1, characterized in that the bottom portion of the shield case extends in the planar direction of the printed circuit board to constitute an electrode section. . 4. The shielded device according to claim 1, characterized in that a conductor for fixing the shield case is formed surrounding the shielded circuit portion and the planar conductor, and the conductor and the shield conductor are connected through a hole. Connection structure between the circuit section and other circuit sections. 5. A connection structure between a shielded circuit section and another circuit section as set forth in claim 1, characterized in that a slit-like cut portion is formed in an end portion of the planar conductor by removing the conductor.