JP2767998B2 - Electronic component shield structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield structure of an electronic component installed near an antenna in a mobile communication device or the like that simultaneously performs transmission and reception.

[Conventional technology]

The portable mobile communication device is configured as shown in FIG. Reference numeral 1 denotes a radio unit, whose box and lid are made of aluminum die-cast and shielded from radio waves. 2
Is a portable cover made of plastic, which has a battery (not shown) inside. An antenna 3 for transmission and reception is exposed from a part of the portable cover 2. Reference numeral 4 denotes a handset which houses a circuit board for transmitting and receiving.

FIG. 7 shows a conventional handset 4 provided with a shield structure.
The internal structure of is shown. An upper cover 41 and a lower cover 42 made of plastic are fitted to the handset 4, and both inner surfaces are painted with a conductive paint. On the circuit board 43 in the upper cover 41, electric components such as a central processing unit (CPU) IC 44 for processing a key signal on the handset 4 and a signal of a display unit, and a crystal oscillator 45 for clock generation are mounted. Have been.

In the conventional portable mobile communication device, when transmitting and receiving at the same time using the transmitting frequency and the receiving frequency, the handset 4 is brought closer to the antenna 3, and when the antenna output is large, the earpiece or the speaker in the handset 4 is cycled from the earpiece or speaker. Often, noise is generated and reception sensitivity is suppressed.

This will be described below. A CPU IC 44 is mounted on the circuit board 43 shown in FIG. 7, and a clock frequency is generated by an oscillator amplifier built in the IC and a crystal oscillator 45 connected thereto. It is working.
The clock waveform is generally a square wave and contains many harmonics of the clock frequency.In addition, since this IC44 operates on a digital signal created by a combination of a LOW voltage and a HIGH voltage with a fixed period, This digital signal also contains frequencies of all components.

As described with reference to FIG. 7, a conductive paint is applied to the inner surfaces of the upper cover 41 and the lower cover 42 in order to prevent external unnecessary radio waves. Has a shield structure surrounded by a conductor.

Radio waves transmitted from the antenna 3 in FIG. 6 are attenuated at a fixed rate by a shield structure made of a conductive material made of a conductive paint inside the handset 4, but the upper cover 41 and the lower cover 42 are fitted. In the fitting, the entire fitting portion cannot be completely formed due to the engagement structure (because a part of the fitting forms a gap), and the shield is incomplete. Furthermore, since the conductive paint is applied only in a grid pattern on the keypad portion on the inner surface of the upper cover 41, the shielding effect is insufficient. For these reasons, if the handset 4 approaches the antenna 3 during a call or the transmission output is large, the circuit board
The transmission wave level reaching 43 reaches a certain level or more.

As described above, the IC44 handles cloak frequencies including harmonics and digital signals including many frequency components, so when a transmission wave level exceeding a certain level reaches the IC44, this transmission frequency and Some of the clock harmonics generated in the IC 44 or some frequency components in the digital signal are mixed in the non-linear portion of the semiconductor in the IC 44. As a result, a reception frequency component of the mobile communication device is generated. If the desired reception wave level reaching the antenna 3 is small, the reception frequency component generated by the IC 44 reaches the antenna 3 and its level is close to or higher than the desired reception wave level reaching the antenna 3. In such a case, the reception sensitivity may be deteriorated, or the frequency or level fluctuation of the digital signal may be demodulated by the radio unit 1 as an audible frequency. As a result, reception may not be possible in a weak electric field area, or noise may be annoying. Also, when the level of the transmission wave reaching the IC 44 is even higher, the IC 44 is rectified by the internal semiconductor, causing a bias fluctuation or the like, causing a malfunction or breakage.

[Problems to be solved by the invention]

In the conventional shield structure of the handset 4 of the portable mobile communication device as described above, the conductive paint is applied to the inner surfaces of the upper cover 41 and the lower cover 42. The problem is that the amount of reduction of wave radiation is insufficient or the dispersion is large, and the conductive paint is expensive, and the coating is applied to the entire inner surface of the upper cover and the lower cover, which is troublesome, time-consuming, and heavy. There was. Furthermore, there is a problem that the means for connecting to the ground plane for releasing the interference wave to the conductive mounting surface is only contact means, and is unstable or difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a shield structure of an electronic component in which the weight is reduced and the cost is reduced as compared with the conventional one, and the interference wave reduction amount is stably obtained. It is intended to be.

[Means for solving the problem]

The shield structure of an electronic component according to the present invention is an electronic component of a mobile radio device, in which a conductive thin film is adhered to a surface of a package thereof, and the conductive thin film is connected to a ground lead or a conductive thin film and a ground surface of a substrate. They are connected by a conductive connector.

[Action]

In the present invention, even if there is an undesired incoming radio wave to the electronic component of the mobile radio device, the incoming wave is captured by the conductive thin film on the surface of the insulating package of the electronic component, and is grounded through the conductor, The interference level can be reliably reduced,
In addition, since the conductive thin film is applied only to the parts that are affected by the unnecessary arriving wave, the implementation is easy.

〔Example〕

FIG. 1 is a perspective view of a handset of a mobile communication device showing a shield structure of an electronic component according to an embodiment of the present invention, and reference numerals 41 to 45 are the same as those in FIG. The IC 44 on the circuit board 43 is provided with a conductive thin film 441 on the upper surface. As the conductive thin film 441, a thin film piece or a thin plate piece made of a good conductor such as a copper thin piece is used.

FIG. 2 shows the IC 44 in a perspective view. IC44 is an insulation package
Leads 44b are protruded from four sides of the side surface 44a, and a plurality of the leads 44b are ground leads 44c. An adhesive is applied to the back surface of the conductive thin film 441, and is adhered to the surface of the package 44a. Reference numeral 442 denotes a linear conductive connector such as a soft copper wire, and the conductive thin film 441 is connected to each ground lead 44c by soldering or the like. Reference numeral 443 denotes a conductive connector made of an annealed copper wire or the like, and which connects the conductive thin film 441 and a ground pattern on the circuit board 43 by soldering or the like.

Unnecessary jamming waves incident on the IC44, which is an electronic component,
Reflected or captured by the conductive thin film 441, the ground plane of the circuit board 43 by the conductive connectors 442 and 443,
That is, the level of the unnecessary interference wave guided to the ground plane and arriving at the element inside the IC 44 is greatly attenuated, and the malfunction does not occur.

In addition, the level of arrival at the internal elements of IC44 is greatly reduced, and the operating range of unwanted wave generation in the non-linear region of the internal elements is narrow and not enough. Does not occur. Further, even if an unnecessary wave is generated by the mixing, the generated unnecessary wave is also radiated from the element itself. However, the unnecessary wave is again captured by the conductive thin film 441 and guided to the ground plane. Therefore, the reception sensitivity is not deteriorated and noise is not generated even in the reception weak electric field area.

The conductive thin film 441 is close to the internal elements of the IC 44 via a package 44a such as a plastic made of an insulating material.
In addition, since it is large with respect to the size of the internal element, it is very effective for the shield to adhere the conductive thin film 441 to the surface of the IC 44 as wide as possible.

In addition, in the ground connection means according to the above-described embodiment, the work becomes more troublesome, especially as the number of the leads 44b increases.

In such a case, the procedure is as shown in FIG. 444 is I
A conductive thin film formed on the surface of the package 44a of C44 by metal plating, and is insulated from the lead 44b outside the ground lead 44c. A conductive connection portion 444a is protruded from the conductive thin film 444, and is connected to the ground lead 44c at a joining point by soldering or the like.

FIG. 4 shows a third embodiment of the present invention. 445 is a so-called flexible conductive plate in which a conductive thin film 447 such as copper foil is formed on one side of a flexible plastic film 446,
It is adhered to the surface of the package 44a with an adhesive. A protruding connection portion 445a is protruded from the flexible conductive plate 445, and is connected to the ground lead 44c and the conductive connection body 443 by soldering or the like.

The means by this flexible conductive plate 445 is suitable when a shielding problem occurs after an electronic component is commercialized, and when a shielding means is added later,
When the number of leads increases, the ground connection operation can be easily performed.

Further, if there is a margin around the component mounting surface on the circuit board 43, it may be configured as shown in FIG. On one side of the flexible plastic film 446, which is slightly larger than the IC 44, a conductive thin film 447 is formed on the surface excluding the vicinity of the end, and a conductive film 449 is formed on both surfaces only at the place to be grounded, thereby forming the conductive thin film on one side. The flexible conductive plate 448 connected to 447 is constituted. This flexible conductive plate 448
Over the IC 44 and soldered to the ground pattern on the circuit board 43 via the through hole 450. According to this means, unnecessary interference radio waves mixed in from the lead 44b of the IC 44 are also shielded.

In the above embodiment, the case of the flat package IC is shown, but the present invention can be applied to a dual-in-line package IC.

In the above embodiment, the conductive thin film is provided on the upper surface of the IC package 44a. However, the conductive thin film may be provided only on the lower surface or on both surfaces.

Further, in the above-described embodiment, the case where an IC is used as an electronic component has been described. However, the present invention can be applied to other types of electronic components that need to shield unwanted interference radio waves.

〔The invention's effect〕

As described above, according to the present invention, it is an electronic component of a mobile radio device, which is provided on a substrate and includes an insulating element having a built-in electric element or circuit for generating a reception frequency component from a transmission wave received therein. A conductive thin film is adhered to the surface of the package, and the conductive thin film and the grounding lead or the conductive thin film and the grounding surface of the substrate are connected by a conductive connector, so that sufficient shielding can be achieved and the internal element is incident or radiated. Unnecessary disturbances can be reliably reduced, or variations can be reduced.Furthermore, connecting means to the ground plane for releasing disturbances to the conductive surface can be stably and easily implemented, resulting in low cost and reduced weight. You.

[Brief description of the drawings]

FIG. 1 is a perspective view of a handset provided with a shield structure according to one embodiment of the present invention with an upper cover removed.
FIG. 3 is a perspective view showing the shield structure of the IC shown in FIG.
4 and 5 are perspective views showing the shield structure of the IC according to the second, third and fourth embodiments of the present invention, FIG. 6 is a perspective view of a portable mobile communication device, and FIG. FIG. 6 is a perspective view of the handset of FIG. 6 in a state where an upper cover using a conventional shield structure is removed. 4 ... Hand set, 41 ... Top cover, 42 ... Bottom cover, 43 ... Circuit board, 44 ... IC, 44a ... Package, 4
4b lead, 44c ground lead, 441 conductive thin film, 442, 443 conductive connector, 444 conductive thin film, 444a
… Conductive connecting portion, 445 flexible conductive plate, 446 plastic film, 447 conductive thin film, 448 flexible conductive plate The same reference numerals in the drawings denote the same or corresponding parts.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-115145 (JP, A) JP-A 63-65344 (JP, U) JP-A 53-24449 (JP, U) JP-A 2- 41449 (JP, U) Actually open sho 64-6097 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05K 9/00

Claims (2)

(57) [Claims] 1. A package provided on a substrate and made of an insulating material containing an electric element or a circuit for generating a reception frequency component from a transmission wave received inside, and a signal input / output or a power supply from the package. In the electronic component of the mobile radio device from which each of the lead to be applied and the ground lead are taken out, a conductive thin film adhered to the surface of the package, and a contact between the conductive thin film and the ground lead or the conductive thin film and the substrate. A shield structure for an electronic component, comprising: a conductive connector connected to the ground. 2. A package provided on a substrate and having a built-in electric element or circuit for generating a reception frequency component from a transmission wave received therein, and a signal input / output or power supply applied from the package. In the electronic component of the mobile radio device from which the lead and the grounding lead are exposed, a flexible conductive plate adhered to the surface of the package and formed on a flexible plastic film with a conductive thin film,
An electronic component, comprising: a conductive connection body connected to a ground plane of the substrate; and a protruding connection portion connecting the conductive thin film of the flexible conductive plate and the grounding lead or the conductive connection body. Shield structure.