JPH0817352B2 - Electronic parts - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component installed in a mobile communication device or the like in the vicinity of an antenna and shielded from electromagnetic waves.

[Conventional technology]

FIG. 5 is an external view showing a portable mobile communication device.
In the figure, reference numeral 1 is a radio unit, and its housing and lid are made of aluminum die-cast, and the inside is shielded.
Reference numeral 2 denotes a plastic portable cover, which has a battery (not shown) built therein. Reference numeral 3 is an antenna for transmitting and receiving, which is emitted from the portable cover. Reference numeral 4 denotes a plastic handset, which has a circuit board inside.

FIG. 6 is an external view showing the internal structure of the handset 4. The handset 4 is configured by combining an upper cover 41 and a lower cover 42, and conductive paint is applied to the inside of the upper cover 41 and the lower cover 42. Then, on the circuit board 40, an IC 43 including a processor for processing key signals and display signals is provided.
And a crystal oscillator 44 that supplies a frequency signal to the IC 43. Further, although not shown in FIG. 6, a circuit pattern for receiving the ON / OFF signal of the key button and other circuit patterns are present on the circuit board 40.

Next, the operation will be described. The operator can talk using the handset 4. In this case, the mobile communication device simultaneously transmits and receives using the transmission frequency and the reception frequency. At that time, when the handset 4 is brought close to the antenna 3 or the antenna output is large,
Noise may be periodically emitted from the earpiece or speaker in the handset 4, or the reception sensitivity may be suppressed.

Next, a phenomenon in which noise occurs or reception sensitivity is suppressed will be described. The IC 43 including the processor is mounted on the circuit board 40 as described above. Then, in the processor, the oscillation amplifier incorporated in the IC 43 operates according to the clock signal created from the frequency signal input from the crystal oscillator 44. Since this clock signal is generally a rectangular wave, it contains harmonic components of the clock frequency. Further, inside the IC 43, digital signals generated by a combination of high level and low level go back and forth. The frequency of every component is also included in this digital signal.

In addition, the upper cover 41 and the lower cover 42 of the handset 4
Since a conductive paint is applied to the inner side of the circuit board in order to prevent interference waves from the outside, when the upper cover 41 and the lower cover 42 are combined, the circuit board 40 has a shield structure surrounded by a conductor. . Therefore, the radio wave transmitted from the antenna 3 is attenuated by the shield structure at a constant rate before reaching the circuit board 40. However, when the upper cover 41 and the lower cover 42 are combined with each other, the inside cannot be completely sealed due to a part of the bending or the like. Therefore, the shield is incomplete. In addition, since the conductive coating material can be applied only in a grid pattern to the portion where the key pads are arranged, as a result, the shielding effect is also lowered. Therefore, when the handset 4 is brought close to the antenna 3 during a call or the transmission output from the antenna 3 is large, the level of the transmission wave reaching the circuit board 40 becomes a certain level or more. When the circuit pattern from the key contact to the IC 43 is long, this circuit pattern also easily picks up the transmitted wave, and the transmitted wave reaching the circuit pattern also reaches the IC 43.

As described above, the IC 43 handles a clock signal containing harmonics and a digital signal containing many frequency components. Therefore, when a transmission wave of a certain level or more arrives at this IC43, the frequency of this transmission wave and the IC
The harmonics of the clock signal of 43 or some frequency components in the digital signal are mixed in the non-linear region of the semiconductor in the IC 43. As a result, a component having the same frequency as the reception frequency of this mobile communication device is also generated. If the level of the original received wave reaching the antenna 3 is low,
If the level of the received frequency component generated by the IC 43 and reaching the antenna 3 is higher or closer to the original received wave level, the reception sensitivity is deteriorated. In addition, the generated audible frequency may be demodulated by the wireless device section 1.
As a result, phenomena such as the inability to receive in a weak electric field region and noise from the earpiece occur. Further, when the level of the transmission wave reaching the IC 43 is higher, the transmission wave is rectified by the internal semiconductor, which may cause a bias fluctuation or the like to cause malfunction or damage.

[Problems to be Solved by the Invention]

Since the electronic components mounted on the conventional circuit board are configured as described above, if conductive paint is used to shield the electronic component surrounded by the plastic cover and the circuit board containing it, the conductive paint will be metal. Since the components are included, the apparatus becomes heavy, and the apparatus becomes expensive due to the price of the conductive paint and the time and effort required for coating. In addition, even if conductive paint is applied to the inside of the plastic cover, it is not possible to realize a perfect shield structure, so there is
It was impossible to completely prevent the arrival at the IC43, and there was the problem that unwanted waves were radiated from the IC43. Further, the connection between the conductive coating surface and the ground surface for releasing the interference radio wave that has reached the conductive coating surface is only due to contact, and there is a problem that the connection becomes unstable.

The present invention has been made to solve the above problems, and eliminates the need for a step of shielding the periphery of an electronic component or a circuit board including the same, such as applying a conductive paint to a plastic cover. It is an object of the present invention to obtain an electronic component that can reduce the weight of the existing device and reduce the cost thereof and that does not radiate unnecessary waves.

[Means for solving the problem]

An electronic component according to the present invention covers an outer surface of an insulating material and has a conductive thin film divided into two regions, one region of the conductive thin film and a grounding lead wire of the electronic component, or a conductive thin film. Connect one area of the conductive thin film to a nearby ground surface such as a ground surface of a circuit board on which electronic components are mounted, or connect one area of the conductive thin film to a grounding lead wire and a nearby ground surface of an electronic component. A ground connection line, a capacitor with one electrode connected to one area of the conductive thin film and the other electrode connected to the other area of the conductive thin film, and the other area of the conductive thin film and the signal input of electronic parts. An output lead wire or a capacitor connection line for connecting the other region of the conductive thin film and a neighboring signal line such as a signal line on a circuit board on which an electronic component is mounted is provided.

[Operation] The conductive thin film according to the present invention captures the interference radio waves arriving at the electronic parts and makes them flow to the ground side, and makes the interference waves intruding from the signal line flow to the ground side via the capacitor and radiates from the electronic parts. The unwanted radio waves are captured and sent to the ground side.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an external view showing a handset including a circuit board 40 on which electronic parts are mounted. In this case, an IC 43 in a plastic flat package is shown as an electronic part. FIG. 2 is an enlarged perspective view of IC43. In the figure, 431 is a thin film piece or a thin plate of a good electric conductor such as a copper foil piece adhered to the surface of the package with an adhesive (hereinafter referred to as a copper thin piece), 432 is a grounding lead wire of IC43, and 433 is a grounding wire. A good conductor in the form of a wire such as an annealed copper wire (hereinafter referred to as annealed copper wire) connected to the lead wire 432 and the copper foil 431 by soldering or the like, and 434 are the copper foil 431 and the ground plane on the circuit board 40. 435 is an annealed copper wire connected to, a signal input / output lead wire of the IC 43 (hereinafter, referred to as a signal lead wire), and 436 is an annealed copper wire connected to the copper thin piece 431 and the signal lead wire 435. Further, the copper thin piece 431 is partially cut to be divided into a ground conductor region and a capacitor electrode conductor region. Then, the capacitor 437 having one electrode connected to the grounding conductor and the other electrode connected to the capacitor electrode conductor,
It is placed on a copper foil 431. The annealed copper wires 433 and 434 are ground connecting wires connected to the grounding conductor of the copper thin piece 431, and the annealed copper wires 436 are capacitor connecting wires connected to the capacitor electrode conductor of the copper thin piece 431.

Next, the operation will be described. Interfering radio waves arriving at the IC 43 from the antenna 1 etc. are reflected by the copper flakes 431.
Or is captured. The captured radio waves are annealed copper wires 433,434.
Guided to the ground plane. As a result, the level of the interfering wave reaching the inside of IC43 is greatly attenuated. Therefore, malfunction of the IC 43 due to the interfering wave does not occur. Further, in the non-linear region of the semiconductor in the IC43, the mixing of the interfering wave and the frequency component in the digital signal does not occur, or even if the mixing occurs, the level of the unnecessary wave generated by the mixing is very small. . This unwanted wave is radiated from IC43,
Since it is captured by and guided to the ground plane, the antenna 3
Does not reach. Therefore, reception sensitivity does not deteriorate and noise does not occur in the weak electric field region.

Since the copper thin piece 431 is close to the chip inside the IC 43 via the plastic, which is an insulating material, and is larger than the chip size, the shielding effect is large. Copper flakes 431
The larger the area of, the greater the shielding effect. In the one shown in FIG. 2, the copper thin piece is bonded to the upper surface of the package, but it may be bonded to the back surface or the side surface of the package. However, when adhering to the side,
It is necessary to avoid contact with the leads of IC43. Although the copper thin piece 431 is connected to the grounding lead wire 432 and the ground plane of the circuit board 40 in the above embodiment, the copper thin piece 431 may be connected to only one side.

In addition, the interfering wave that has entered the circuit pattern of the circuit board 40 is generated by the capacitor 437 mounted on the upper part of the IC 43.
As it is bypassed before entering the inside of C43, I
It does not affect the C43 chip. Especially when bypassing high frequencies, it is necessary to provide a bypass capacitor 437 as close as possible to the IC43 in order to remove the parasitic inductance component and enhance the interference wave removal effect. Placing 437 is effective. In addition, the annealed copper wire 436 is replaced with the copper thin piece 431.
And the portion of the signal pattern on the circuit board 40 near the IC 43 may be connected.

In the above embodiment, the copper foil 43 is formed on the outer surface of the package of the IC43.
Bond 1 to ground lead wire 432 of IC43 or circuit board
40 copper planes (or both) and copper strips 431
Connect with 33, 434, IC43 signal lead wire 435
I tried to connect the copper thin piece 435 and the copper thin piece 435 with the annealed copper wire 436.
If the number of lead wires of 43 is large, connection work may be difficult. In such a case, as shown in FIG.
Metal plating 438 may be applied instead of the copper flakes 431. The portions corresponding to the annealed copper wires 433 and 436 are also formed by metal plating. In the case of such a configuration, a package having heat resistance such as ceramic is preferable as the package. Further, the grounding lead wire 432 and the signal lead wire 435 may be connected to the metal plating 438 by soldering.

Further, as shown in FIG. 4, a conductive film such as a copper foil is formed on one surface of a flexible plastic, and a capacitor 437 is formed on the conductive film.
The flexible substrate 439 on which is mounted may be bonded to the package of the IC 43. In this case, flexible board 439
Can be easily adhered, which is convenient when a problem occurs after the product such as the handset 4 is completed, and the problem can be dealt with.

In addition, in each of the above-described embodiments, the IC43 of the flat package has been described, but the IC43 of the dual-in-line package can be configured in the same manner and the same effect can be obtained.

〔The invention's effect〕

As described above, according to the present invention, an electronic component is provided with a conductive thin film on the outer surface of an insulating material, and the conductive thin film is connected to a grounding lead wire or a nearby grounding surface to prevent interference with a signal lead wire. Since a capacitor that bypasses the wave is mounted, it is possible to reliably prevent an interfering wave that enters the electronic component and an unnecessary wave that radiates from the electronic component, and also reduce the weight of the device incorporating the electronic component. There is an effect that the thing which makes the price low can be obtained.

[Brief description of drawings]

FIG. 1 is an external view showing a handset on which an electronic component according to an embodiment of the present invention is mounted, FIG. 2 is a perspective view showing an electronic component according to an embodiment of the present invention, and FIGS. FIG. 5 is a perspective view showing an electronic component according to another embodiment of the present invention, FIG. 5 is an external view showing a portable mobile communication device, and FIG.
FIG. 1 is an external view showing a handset having a shield structure in which a conventional electronic component is mounted. 40 is a circuit board, 43 is an IC (electronic component), 431 is a copper thin piece (conductive thin film), 432 is a ground lead wire, 433 and 434 are annealed copper wires (ground connection wire), 435 is a signal lead wire, and 436 is annealed copper. Line (capacitor connection line), 437 is a capacitor. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An electronic component having lead wires for signal input / output, a power supply, and a ground, the surface of which is covered with an insulating material, the outer surface of the insulating material being covered and divided into two regions. A conductive thin film, one region of the conductive thin film and the lead wire for grounding, or one region of the conductive thin film and a nearby ground plane, or one region of the conductive thin film and the A ground connecting wire connecting the grounding lead wire and the neighboring ground plane, and one electrode connected to one region of the conductive thin film and the other electrode connected to the other region of the conductive thin film. A capacitor and a capacitor connecting line connecting the other region of the conductive thin film and a lead wire for inputting and outputting the signal, or a capacitor connecting line connecting the other region of the conductive thin film and a neighboring signal line. Characteristic electronic parts.