JP5466887B2 - Shield plate, portable communication terminal, and method for identifying a portion of a through hole established in a shield plate - Google Patents

Description

  The present invention relates to a shield plate for suppressing electromagnetic wave noise, and a portable communication terminal including the shield plate, and more particularly to a shield plate for preventing electromagnetic wave noise generated from an IC from returning to an antenna.

  In order to avoid a phenomenon that electromagnetic wave noise generated from a digital IC (Integrated Circuit: integrated circuit) mainly responsible for digital signal processing in the mobile communication terminal is fed back to the antenna and the communication status of the mobile communication terminal deteriorates. By covering the digital IC with a shield plate, a countermeasure is taken to suppress feedback of electromagnetic noise generated from the digital IC to the antenna (for example, see Patent Document 1).

In addition, in order to realize more functions with a smaller terminal, mobile communication terminals can reduce the number of parts by integrating multiple parts into one part and reduce the distance between parts. Efforts are being made to mount components in smaller volumes.
As for ICs that are parts of portable communication terminals, the above-described digital ICs and RFICs (Radio Frequency Integrated Circuits) mainly responsible for communication-related high-frequency analog signal processing are combined into one IC (hereinafter referred to as a digital-analog mixed IC). Is being integrated.

JP 2004-72051 A

  However, by making the digital IC and the RFIC into one digital / analog mixed IC, electromagnetic noise generated from the digital IC portion of the digital / analog mixed IC propagates through the shield plate, and the LNA in the RFIC portion of the same digital / analog mixed IC A phenomenon occurs in which the feedback sensitivity of the RFIC unit deteriorates due to feedback to (Low Noise Amplifier).

It has been confirmed that this reception sensitivity deterioration can be improved by separating the digital-analog mixed IC and the shield plate by 2 mm or more, or by inserting an electromagnetic wave absorber between the digital-analog mixed IC and the shield plate. This method has a problem that the size of the mobile communication terminal becomes large, and the latter method has a problem that the cost of the mobile communication terminal increases.
Therefore, the present invention has been made in view of such problems, and a shield plate that suppresses the return of electromagnetic wave noise of an IC, a mobile communication terminal using the shield plate, and a through hole established in the shield plate. An object is to provide a method for identifying a site.

  In order to solve the above-described problem, an IC including a digital circuit and an analog circuit is mounted on a substrate, and the shield plate according to the present invention is configured to suppress transmission of electromagnetic noise emitted by the digital circuit of the IC. A through-hole is formed in a portion corresponding to a region on the main surface of the IC that is a region on the main surface of the IC that reduces the performance of the analog circuit of the IC when receiving a predetermined electromagnetic wave. It is characterized by that.

  Here, the predetermined electromagnetic wave is caused by the electromagnetic wave reapplied to the IC when the electromagnetic wave noise emitted by the digital circuit of the IC propagates through the shield plate without the through hole and is applied to the IC again. The strength, frequency, etc. are determined so as to reproduce the influence of the IC on the analog circuit.

  The shield plate according to the present invention having the above-described configuration can suppress the return of IC electromagnetic noise.

It is a perspective view of the portable communication terminal housing | casing 100 which has notched a part so that an internal structure may be shown. 2 is an exploded perspective view of a structure housed in a mobile communication terminal housing 100. FIG. It is a top view of the main surface of digital-analog mixed IC130. 6 is a plan view of the vicinity of the digital / analog mixed IC 130 as viewed from above the shield plate 120. FIG. 6 is a plan view of the vicinity of the digital / analog mixed IC 130 with the shield plate 120 removed, as viewed from above the shield frame 110. FIG. It is a figure which shows the condition which is measuring the AGC value of digital / analog mixed IC130. 5 is a flowchart illustrating a method for specifying a portion of a through hole 140. It is a figure which shows the correspondence of a small area | region name and an AGC value. It is a figure which shows the condition which is measuring the electromagnetic wave noise of Digiana mixed IC130. It is a flowchart which shows the method of specifying the position which arrange | positions the chucking flat plate part 110B.

<Embodiment>
Hereinafter, as an embodiment of a shield plate and a mobile communication terminal according to the present invention, a mobile communication terminal using a shield plate having a through hole will be described.
<Overview>
In the mobile communication terminal according to the present embodiment, in order to suppress the adverse effect that electromagnetic wave noise emitted from the digital / analog mixed IC arranged on the substrate returns to the antenna and affects the communication of the mobile communication terminal, A shield plate is arranged at a position covering the whole, and a shield frame is arranged so as to surround a digital / analog mixed IC sandwiched between the substrate and the shield plate.

  This shield plate has a through-hole, and the part where this through-hole is open is electromagnetic noise generated from the digital signal processing unit mainly responsible for digital signal processing of the digital / analog mixed IC propagates on the surface of the shield plate, The main surface of the digital / analog mixed IC faces an area that adversely affects the RF circuit when receiving an electromagnetic wave so as not to return to the RF circuit that mainly handles high-frequency analog signal processing of the same digital / analog mixed IC.

  In addition, the shield frame has a plate-like structure for chucking (sucking) by a chucking tool represented by a suction disk, etc., necessary for carrying the shield frame in the mobile communication terminal assembly process. There is a flat plate portion, and the position of the chucking flat plate portion is a position that covers a region of the main surface of the IC excluding a region that, when receiving a predetermined electromagnetic wave, degrades the performance of the RF circuit below the predetermined performance. The chucking flat plate portion also serves as a shield that suppresses propagation of electromagnetic wave noise generated by the digital signal processing portion of the digital / analog mixed IC to the shield plate.

This portable communication terminal uses electromagnetic waves in the 800 MHz band and the 2 GHz band having wavelengths of about 375 mm and about 150 mm, respectively, for communication.
With respect to the size of this wavelength, the size of the through hole is only about the size of a 12 mm square, which is the size of the main surface of the digital / analog mixed IC. Therefore, since the size of the through hole is sufficiently smaller than the wavelength of the electromagnetic wave used for communication, electromagnetic waves in these frequency bands cannot pass through the through hole.
<Configuration>
The configuration of the mobile communication terminal according to the present embodiment will be described below with reference to the drawings.

FIG. 1 is a perspective view of a state in which a foldable mobile communication terminal 1000 is opened, and a part of the mobile communication terminal housing 100 is cut out to show the internal structure.
FIG. 2 is an exploded perspective view of a structure housed in the mobile communication terminal housing 100.
As can be seen from the figure, the substrate 150 is a circuit board in which electronic components are arranged on the surface and the terminals of the electronic components are electrically connected.

The shield plate 120 is a metal plate having a thickness of 0.1 mm, and is disposed at a position covering the entire main surface of the digital / analog mixed IC 130 disposed on the substrate 150.
The shield wall portion 110A is a metal wall with a height of 1.3 mm and a thickness of 0.2 mm that stands on the substrate 150, and is sandwiched between the substrate 150 and the shield plate 120 to surround the digital / analog mixed IC 130. Yes.

The shield plate 120 is provided with a through hole 140 at a predetermined site. The part of the through hole 140 will be described later.
The chucking flat plate portion 110 </ b> B has a plate-like structure in order to facilitate suction by a suction disk or the like necessary for carrying the shield frame 110 in the assembly process of the mobile communication terminal 1000.

  The electromagnetic wave noise generated by the digital signal processing unit of the digital / analog mixed IC 130 is reduced by placing the chucking flat plate portion 110 </ b> B necessary in the assembly process at a position between the digital / analog mixed IC 130 and the shield plate 120. Propagation to 120 is suppressed. The positional relationship between the chucking flat plate portion 110B and the digital / analog mixed IC 130 will be described later.

The shield frame 110 is fixed by soldering to the ground wiring of the substrate 150, and the shield plate 120 is fixed by inserting 40 protrusions into the 40 insertion openings of the shield frame 110, and the shield frame 110 and the shield frame 110 are shielded. The potential of the plate 120 is the ground potential of the substrate.
The antenna 220 is an antenna for performing wireless communication between the mobile communication terminal 1000 and the base station, and is connected to the substrate 150 via the antenna connection module 210.

By adopting a structure that surrounds the digital / analog mixed IC 130 with the substrate 150, the shield frame 110, and the shield plate 120, electromagnetic wave noise emitted by the digital signal processing unit of the digital / analog mixed IC 130 is prevented from returning to the antenna 220. .
Hereinafter, the positional relationship between the digital / analog mixed IC 130, the through hole 140 in the shield plate 120, and the chucking flat plate portion 110B will be described with reference to FIGS.

FIG. 3 is a diagram showing that the main surface of the digital / analog mixed IC 130 is virtually divided into 16 small regions.
Virtually categorizing does not actually divide the main surface of the digital / analog mixed IC 130, but when processing to search for electromagnetic wave fragile regions, the system guarantees that each small region can be searched. It means being.

The digital / analog mixed IC 130 is a rectangular parallelepiped whose main surface is a square having a side of 12 mm and a height of 1.0 mm. This main surface is virtually divided into 16 small areas with names A to P each having a square of 3 mm on a side, and electromagnetic waves are applied spot-wise to each of these small areas.
FIG. 4 is a plan view of a state in which the digital / analog mixed IC 130, the shield frame 110, and the shield plate 120 are assembled on the substrate 150 as viewed from above the shield plate 120.

The through-hole region 410 is a region composed of the small regions A, B, C, and E of the digital / analog mixed IC 130 and is a fragile region that reduces the performance of the RFIC portion of the digital / analog mixed IC 130 to a predetermined level or less when a predetermined electromagnetic wave is applied. .
The through-hole 140 is a through-hole opened at a position facing the through-hole region 410, and is drilled with an accuracy of several tens of μm by a metal plate punching device so as to have the same shape as the through-hole region 410. ing.

In FIG. 4, in order to make the relationship between the through hole 140 and the through hole region 410 easy to understand, the through hole 140 is expressed so as to be slightly larger than the through hole region 410. As you can see, they are the same size.
A method for specifying that the through-hole region 410 is composed of the small regions A, B, C, and E of the digital / analog mixed IC 130 will be described later.

As shown in FIG. 4, the chucking flat plate portion 110 </ b> B is arranged at a position covering the upper right portion of the main surface of the digital / analog mixed IC 130 from the through-hole region 410 so as not to cover the through-hole region 410. It has become.
Details of the positional relationship between the chucking flat plate portion 110B and the digital / analog mixed IC 130 will be described below with reference to FIG.

FIG. 5 is a plan view of the state where the shield plate 120 is removed from the state shown in FIG. 4 as viewed from above the shield frame 110, and cannot be directly seen by being shielded by the shield frame 110. The part of the mixed IC is indicated by a broken line.
The chucking flat plate portion 110B has a thickness of 0.2 mm, and includes all of the small areas K, L, O, and P of the digital / analog mixed IC, and some areas of the small areas N, J, F, G, and H. It is arranged at a position to cover.

A method for specifying that the position at which the chucking flat plate portion 110B is disposed is the position described above will be described later.
The left arm portion 110C and the right arm portion 110D are reinforcing members for reinforcing the strength of the shield frame 110 by connecting them to the shield wall portion 110A with a thickness of 0.2 mm extending from the chucking flat plate portion 110B to the left and right.
<Method of creating a through hole>
Hereinafter, a specific person who specifies the part of the through hole 140 specifies the part of the through hole 140 by manual operation, and an operator who opens the through hole 140 in the shield plate 120 includes several parts in the specified part of the through hole 140. A method of making a hole using a metal plate punching apparatus capable of making a hole in a metal plate with an error of 10 μm will be described with reference to the drawings.

  6 is processed so as not to affect the operation of the mobile communication terminal 1000, a hole is formed in a part of the mobile communication terminal housing 100, and the shield plate 120 of the mobile communication terminal 1000 shown in FIG. It is a figure which shows the condition where the power of the portable communication terminal 1000 is turned on and the performance of the portable communication terminal 1000 is measured with the shield frame 110 removed. However, here, in order to make the explanation easy to understand, the size of the hole formed in a part of the mobile communication terminal housing 100 is greatly emphasized. Instead of opening the hole, for example, the upper lid of the mobile communication terminal housing 100 may be removed.

The signal generator 520 is an electromagnetic wave generator that generates an electromagnetic wave by setting a frequency and an intensity. Here, the signal generator 520 has an intensity of −50 dBm at a frequency of 870 MHz from the tip of the rod-shaped antenna 510 by the signal generator 520. Set to generate electromagnetic waves.
When the shield plate 120 does not have the through hole 140, the electromagnetic wave noise emitted from the digital circuit of the digital / analog mixed IC 130 propagates through the shield plate 120 and is applied to the digital / analog mixed IC 130 again. The setting is determined so as to reproduce the influence on the RF circuit section of the digital / analog mixed IC 130 by the electromagnetic wave applied again.

The rod-shaped antenna 510 can receive the electromagnetic wave generated by the signal generator 520 via the cable 550 and individually apply it to each of the small areas on the main surface of the digital / analog mixed IC 130.
The connector 540 is a component that configures the mobile communication terminal 1000 outside the mobile communication terminal 1000 by connecting to the socket at the bottom of the mobile communication terminal housing 100 in order to adjust the components that configure the mobile communication terminal 1000. The information of is output.

  The digital / analog mixed IC 130 includes an AGC value output terminal that outputs an AGC (Automatic Gain Control) value used by the LNA in the RF circuit unit of the digital / analog mixed IC 130. The connector 540 can output the AGC value as an output via the socket of the substrate 150 and the portable communication terminal housing 100.

The AGC value output from the connector 540 is sent to the AGC value display device 530 via the cable 560, and the AGC value display device 530 displays the received AGC value.
This AGC value is a value that is displayed by converting the level difference from the reference to dB with reference to an intensity of −90 dBm. The larger the AGC value, the more the degradation of the performance of the RF circuit section of the digital / analog mixed IC. It shows that it is big.

By taking the above-described configuration, the specific person operates the rod-shaped antenna 510 to operate the mobile communication terminal 1000 in a state where a specific electromagnetic wave is applied to each of the small areas on the main surface of the digital / analog mixed IC 130. The AGC value used by the LNA in the RF circuit section of the digital / analog mixed IC 130 can be displayed on the AGC value display device 530.
FIG. 7 is a flowchart for specifying a portion of the through hole 140 opened in the shield plate 120 by the specific person.

The specific person turns on the mobile communication terminal 1000 to activate the mobile communication terminal 1000, and sets the reception mode that is a standby state from the base station (step S100).
Next, as shown in FIG. 3, the specific person sees a virtual partition diagram that is an enlarged view showing that the main surface of the digital / analog mixed IC 130 is virtually partitioned into 16 small regions A to P. Thus, an electromagnetic wave having an intensity of −50 dBm at a frequency of 870 MHz is applied to the region of the main surface of the digital / analog mixed IC 130 corresponding to the small region A on the small region division diagram.

The AGC value displayed by the AGC value display device 530 is measured in a state where an electromagnetic wave is applied, and the measured AGC value is recorded (step S110).
When the recording of the AGC value of the main surface area of the digital / analog mixed IC 130 corresponding to the small area A is completed, the AGC value of the main surface area of the digital / analog mixed IC 130 corresponding to the small area B of the small area division diagram is calculated in the same manner. (Step S120: Yes, Step S130, Step S110).

  In order according to the alphabetical order, the AGC value of the area of the main surface of the digital / analog mixed IC 130 corresponding to each small area on the small area division diagram is measured and recorded (step S120: Yes, step S130, and step S110 are repeated) When the measurement and recording of the AGC value of the main surface area of the digital / analog mixed IC 130 corresponding to the small area P is completed (step S120: No), the AGC value measurement is ended.

The specific person determines whether or not the AGC value recorded for each small area is equal to or greater than a predetermined AGC value, and the digital / analog mixed IC 130 does not satisfy the predetermined performance for the small area that is equal to or greater than the predetermined AGC value. It determines with it being a small area | region and specifies with a through-hole area | region (step S140).
Finally, a specific person specifies that the part of the shield plate which opposes a through-hole area | region is a site | part of a through-hole (step S150).

In the following, a method for specifying the site of the through-hole will be described by taking as an example the case where the small regions having the predetermined AGC value of 10 dB and the AGC value of 10 dB or more are the small regions A, B, C, and E. .
The specific person activates the mobile communication terminal 1000 (step S100), and as described above, the AGC value of the main surface area of the digital / analog mixed IC 130 corresponding to each small area is changed from the small area A to the small area P in alphabetical order. Measure and record (step S110, step S120: Yes, repeat step S130, and finally step S120: No).

FIG. 8 is a table in which AGC values recorded by a specific person measured and recorded for each of the small areas A to P are listed, and in the “part of the through-hole area” column in the figure, When the measured AGC value is 10 dB or more, ◯ is entered when it is less than 10 dB.
Here, as shown in FIG. 8, since the through hole region 410 having an AGC value of 10 dB or more is the small regions A, B, C, and E, the specific person can reduce the through hole region 410 in FIG. It is specified that the region is composed of regions A, B, C, and E (step S140), and the portion of the shield plate that faces this through-hole region 410 is specified as the portion of the through-hole 140 (step S150).

  According to the above-described method, when the through hole 140 is not formed in the shield plate 120, the electromagnetic noise emitted by the digital circuit of the digital / analog mixed IC 130 propagates through the shield plate 120 so that the digital / analog mixed again. When applied to the IC 130, it can be specified that the part of the shield plate 120 is opposed to the part where the influence on the RF circuit part of the digital / analog mixed IC 130 is 10 dB or more due to the re-applied electromagnetic wave.

Thereafter, the operator inputs the coordinates on the shield plate 120 indicating the part of the through hole 140 specified by the specific person into the metal plate punching apparatus capable of punching the metal plate with an accuracy of several tens of μm. By punching the coordinate portion input to the plate 120, the through-hole 140 is formed in the same shape as the through-hole region 410 with an accuracy of several tens of μm.
<Method of specifying the position where the chucking flat plate portion is disposed>
Hereinafter, the person who specifies the position where the chucking flat plate portion 110B is arranged manually specifies the position where the chucking flat plate portion 110B is arranged, and the operator who creates the shield frame chucks the specified position. A method of creating the flat plate portion 110B will be described with reference to the drawings.

  9 is processed so as not to affect the operation of the mobile communication terminal 1000, a hole is formed in a part of the mobile communication terminal housing 100, and the shield plate 120 of the mobile communication terminal 1000 shown in FIG. It is a figure which shows the condition which turns on the power supply of the portable communication terminal 1000 in the state which removed the shield frame 110, and is measuring the electromagnetic waves which the digital-analog mixed IC130 discharge | releases. However, as in FIG. 6, the size of the hole opened in a part of the mobile communication terminal housing 100 is greatly emphasized for easy understanding. Instead of opening the hole, for example, the top cover of the mobile communication terminal housing 100 may be removed.

The spectrum analyzer 610 is a device that can display an input electrical signal on a screen as a two-dimensional graph with the horizontal axis representing frequency and the vertical axis representing power, and the frequency of electromagnetic waves input from the cable 640 The power is displayed on the screen as a two-dimensional graph.
The rod-shaped antenna 650 receives electromagnetic waves emitted from each of the small regions on the main surface of the digital / analog mixed IC 130, and transmits the received electromagnetic waves to the amplifier 620 via the cable 630.

The amplifier 620 amplifies the electromagnetic wave sent from the cable 630 with a gain of 20 dBm and outputs it to the cable 640.
With the above-described configuration, the specific person can visually check the electromagnetic wave emitted from each of the small regions on the main surface of the digital / analog mixed IC 130 with the spectrum analyzer 610.

Hereinafter, the specific person who specifies the position where the chucking flat plate portion 110B is arranged manually specifies the position where the chucking flat plate portion 110B is arranged, and the operator who creates the shield frame specifies the chucking flat plate portion 110B. A method of creating a shield frame in which the chucking flat plate portion is arranged at the position will be described with reference to the drawings.
FIG. 10 is a flowchart showing a method of specifying a position where the specific person manually places the chucking flat plate portion 110B.

The specific person turns on the mobile communication terminal 1000 to activate the mobile communication terminal 1000, and sets the reception mode that is a standby state from the base station (step S200).
Next, as shown in FIG. 3, the specific person looks at the virtual section diagram which is an enlarged view showing that the main surface of the digital / analog mixed IC 130 is virtually partitioned into 16 small regions A to P. Then, by operating the rod-shaped antenna 650, the electromagnetic wave emitted from the main surface of the digital / analog mixed IC 130 corresponding to the small area A on the small area division diagram is visually confirmed on the screen of the spectrum analyzer 610 (step S210). .

  When the specific person confirms that an electromagnetic wave having a predetermined intensity or more is emitted from the area of the digital / analog mixed IC 130 corresponding to the small area A (step S220: Yes), the digital / analog mixed corresponding to the small area A It is confirmed whether the region of the main surface of the IC 130 is a part of the through-hole region 410 or a small region adjacent to the through-hole region 410, and the small surface adjacent to the through-hole region 410 is not the through-hole region 410. If it is not an area (step S225: Yes), the area of the main surface of the digital / analog mixed IC 130 corresponding to the small area A is specified as a part of the chucking area and recorded (step S230).

  When it is not confirmed that the electromagnetic wave having a predetermined intensity or higher is emitted from the area of the digital / analog mixed IC 130 corresponding to the small area A (step S220: No), the main area of the digital / analog mixed IC 130 corresponding to the small area A is displayed. When the surface region is a part of the through-hole region 410 or a small region adjacent to the through-hole region 410 (step S225: No), the main surface of the digital / analog mixed IC 130 corresponding to the small region A Is not specified as a part of the chucking area.

  When it is confirmed whether or not electromagnetic waves having a predetermined intensity or more are emitted from the main surface area of the digital / analog mixed IC 130 corresponding to the small area A, the small areas on the small area division diagram are sequentially displayed in alphabetical order. It is confirmed whether or not an electromagnetic wave having a predetermined intensity or more is emitted from the main surface area of the digital / analog mixed IC 130 corresponding to the area (step S240: Yes, step S250, step S210, step S220, step S225, When step S230 is repeated), when it is confirmed whether or not electromagnetic waves having a predetermined intensity or higher have been emitted from the main surface area of the digital / analog mixed IC 130 corresponding to the small area P (step S240: No), End measurement.

A specific person specifies the position which covers all the area | regions identified as a part of chucking area | region among the area | regions of the main surface of a digital-ana mixed IC as a position which arrange | positions the chucking flat plate part 110B (step S260).
Hereinafter, the area of the main surface of the digital / analog mixed IC 130 corresponding to a small area that emits an electromagnetic wave having a strength equal to or greater than the intensity of a predetermined electromagnetic wave corresponds to the digital / analog mixed IC 130 corresponding to the small areas D, G, K, L, O, and P. A method of specifying the position where the chucking flat plate portion is arranged will be described by taking the case of the region of the main surface as an example.

The specific person activates the mobile communication terminal 1000 (step S200), and, as described above, the electromagnetic waves emitted from the main surface area of the digital / analog mixed IC 130 corresponding to each small area are displayed in alphabetical order from the small area A to the small area P. (Steps S210 to S250 are repeated, and finally step S240: No).
At this time, an electromagnetic wave having a strength greater than or equal to a predetermined strength is emitted from the main surface region of the digital / analog mixed IC 130 corresponding to the small regions A, B, C, E, F, H, I, J, M, and N. Since this is not confirmed (step S220: No), it is not specified to be a part of the chucking area.

Since the main surface area of the digital / analog mixed IC 130 corresponding to the small areas D and G is a small area adjacent to the through-hole area 410 (step S225: No), it is specified as a part of the chucking area. There is no.
The main surface area of the digital / analog mixed IC 130 corresponding to the small areas K, L, O, and P is confirmed to emit an electromagnetic wave having a predetermined intensity or more (step S220: Yes). However, since it is not a small region adjacent to the through-hole region 410 (step S225: Yes), it is specified as a part of the chucking region.

Since the area of the main surface of the digital / analog mixed IC 130 corresponding to the small areas K, L, O, and P is specified to be a part of the chucking area, the position of the chucking flat plate portion 110B in FIG. A position that covers the entire area of the main surface of the digital / analog mixed IC 130 corresponding to the small areas K, L, O, and P is specified as a position where the chucking flat plate portion 110B is disposed (step S260).
In FIG. 5, the chucking flat plate portion 110 </ b> B covers a part of the main surface area of the digital / analog mixed IC 130 corresponding to the small areas F, G, H, J, and N, but the small areas K, L, O, Only the region of the main surface of the digital / analog mixed IC 130 corresponding to P may be covered.

Of the positions that do not cover the through-hole area 410 and its adjacent areas, the position that covers the small area that generates electromagnetic wave noise is identified as the position at which the chucking flat plate portion 110B is disposed.
Accordingly, the chucking flat plate portion 110B can be disposed at a position where electromagnetic wave noise generated by the digital / analog mixed IC 130 is prevented from propagating to the shield plate 120, and the chucking flat plate portion 110B covers the through-hole region 410. Since the electromagnetic noise generated by the digital / analog mixed IC is propagated through the chucking flat plate portion 110B and is not applied to the through-hole region 410 again, the chucking flat plate portion 110B is arranged. It can be identified as a position.

Thereafter, the operator creates a mold for the shield frame 110 in accordance with the position where the chucking flat plate portion 110B specified by the specific person is arranged, and uses this mold to create the shield frame 110, thereby specifying the specific person. The shield frame in which the chucking flat plate portion 110B is arranged at the position where the chucking flat plate portion 110B specified by is created.
The shield plate having the above-described configuration has a through hole, and the region on the main surface of the IC corresponding to the through hole is a region that reduces the performance of an analog circuit such as an RF circuit of the IC when receiving a predetermined electromagnetic wave. It has become.

By opening a through hole in the shield plate, electromagnetic noise emitted by the digital circuit of the IC does not propagate through the shield plate covering the IC to the region of the main surface of the IC that is to face the through hole. .
Accordingly, it is possible to suppress the amount of propagation of electromagnetic noise emitted by the digital circuit of the IC through the shield plate to a region where the performance of the analog circuit of the IC is deteriorated when receiving a predetermined electromagnetic wave. It is possible to provide a shield plate that suppresses the performance of the analog circuit from deteriorating from a predetermined performance.

By using this shield plate as, for example, a shield plate for a portable communication terminal equipped with a digital / analog mixed IC, there is no need to leave a gap of 2 mm or more between the digital / analog mixed IC and the shield plate, and the gap between the digital / analog mixed IC and the shield plate is not necessary. Therefore, there is no need to insert an electromagnetic wave absorber, so that it is possible to provide a shield plate without increasing the size of the mobile phone terminal and without increasing the cost of the mobile communication terminal.
<Supplement>
As described above, as an embodiment of the shield plate and the mobile communication terminal according to the present invention, the mobile communication terminal using the shield plate with the through hole and the shield frame with the chucking flat plate portion, and the shield plate according to the present invention Although the method for specifying the position of the through hole of the shield plate used in the mobile communication terminal has been described as one embodiment of the creation method, the present invention can be modified as follows, and the present invention is the embodiment described above. Of course, it is not limited to the shield plate, the mobile communication terminal, and the shield plate creation method as shown.
(1) In the embodiment, the main surface of the digital / analog mixed IC 130 has been described as virtually divided into 16 square small areas A to P. However, the main surface is virtually divided into small areas having other numbers and shapes. It doesn't matter.

By dividing into more than 16 small regions, it is possible to specify the portion where the through-hole is opened more finely.
In addition, the number of small regions is substantially meaningful due to the relationship between the size of the main surface of the digital-analog mixed IC 130 and the size of the rod-shaped antenna 510, the performance of the rod-shaped antenna 510, the configuration of the digital-analog mixed IC 130, and the like. In such a case, even if the number is less than 16, it is possible to specify the site where the through-hole is opened with sufficient accuracy.

With regard to the shape of the small region, there may be a case where the shape of the shape other than the square can be specified more finely by the relationship between the shape of the digital / analog mixed IC 130 and the shape of the rod-shaped antenna 510. In such a case, it is possible to specify a portion where the through hole is opened with sufficient accuracy even if the shape is other than a square.
(2) In the embodiment, the case where the shape of the through-hole 140 is an L-shape has been described. However, the shape and number of small areas that divide the main surface of the digital / analog mixed IC 130, the internal shape of the digital / analog mixed IC 130, and the inside Since the part where the through hole 140 is opened is determined depending on the configuration and the like, there is a possibility of taking various shapes other than the L shape, and as a result, the shape of the through hole 140 is not limited to the L shape. In some cases, there may be a plurality of through holes.
(3) In the embodiment, the position of the chucking flat plate portion 110B is a position that covers the entire chucking area, but may be a position that covers a part of the chucking area instead of the entire chucking area.

The effect of shielding the electromagnetic wave emitted by the digital / analog mixed IC 130 becomes more conspicuous when the entire chucking area is covered. However, the digital / analog mixed IC 130 emits only by covering a part rather than the entire chucking area. In order to bring about an effect of shielding the electromagnetic wave to be performed, it may be preferable that the position of the chucking flat plate portion 110B covers a part of the chucking region instead of the whole of the chucking region for reasons of assembly process.
(4) In the embodiment, the setting of the signal generator 520 generates an electromagnetic wave having an intensity of −50 dBm at a frequency of 870 MHz from the rod-shaped antenna 510 toward each of the small areas on the main surface of the digital / analog mixed IC 130. Although described as being set as such, it is not limited to these values. For example, it may be set to generate an electromagnetic wave having an intensity of −50 dBm at a frequency of 2 GHz.

At this time, the frequency and intensity of the electromagnetic wave to be set is a case where it is assumed that there is no through hole in the shield plate, and the electromagnetic wave noise emitted by the digital circuit of the digital / analog mixed IC 130 is reduced to the shield plate without the through hole. When the signal is propagated through the digital signal and again applied to the digital / analog mixed IC 130, the frequency and intensity are set so as to reproduce the influence on the RF circuit unit of the digital / analog mixed IC 130 caused by the electromagnetic wave applied again to the digital / analog mixed IC 130. Any setting can be used.
(5) In the embodiment, as an index for determining whether or not the small region is a part of the through-hole region, the AGC value used by the LNA, and the level difference from the reference on the basis of the intensity −90 dBm Is a value that is 10 dB in terms of dB, but a value other than 10 dB may be used as an index, an AGC value determined by a method other than this may be used as an index, and a value other than an AGC value may be used. Even if it is an index, any index may be used as long as it indicates the degree of deterioration of the performance of the RF circuit unit of the digital / analog mixed IC 130.
(6) In the embodiment, it is a necessary condition for the chucking area not to be a small area adjacent to the through-hole area 410. However, this condition may not be used.

As a result, the position where the electromagnetic wave noise generated by the digital / analog mixed IC 130 propagates through the chucking flat plate portion 110B and is not applied to the through-hole region 410 again is specified as the position of the chucking flat plate portion 110B. Any condition can be used as long as it is possible.
(7) In the embodiment, the metal has been described as the material of the shield plate 120 and the shield frame 110, but any material other than metal may be used as long as the material suppresses transmission of electromagnetic waves.
(8) In the embodiment, the shape of the through-hole 140 is the same shape as the through-hole region 410 with an accuracy of several tens of μm. However, if the portion facing the chucking region is not included, the target electromagnetic wave The shape may be larger than the through-hole region 410 within a range that is sufficiently smaller than the wavelength.

When the shape is larger than the through-hole region 410, the electromagnetic noise generated by the digital / analog mixed IC 130 propagates through the chucking flat plate portion 110B, and the electromagnetic wave applied to the through-hole region 410 again does not increase. If the chucking region, which is an electromagnetic wave generating region, does not include a portion where the through hole 140 is opposed, the through hole 140 is sufficiently small compared to the wavelength of the electromagnetic wave, so that the electromagnetic wave passes through the through hole 140. There is no end to it.
(9) In the embodiment, the case where the specific person manually specifies the portion of the through hole 140 has been described. However, all or part of the automatic operation is automatically performed using a device that operates according to a program described in software. You may make it process it. In addition, the case where the specific person manually specifies the position where the chucking flat plate portion 110B is arranged has been described. However, all or part of the specification is automatically performed using a device that operates according to a program described in software. You may make it process.
(10) In the embodiment, the shield frame 110 has been described as including the left arm portion 110C and the right arm portion 110D as reinforcing materials for reinforcing the strength. However, the shield frame 110 may not include the reinforcing material. A reinforcing material having a shape other than this may be provided.
(11) In the embodiment, the thickness of the shield plate 120 is 0.1 mm, the thickness of the chucking flat plate portion 110B is 0.2 mm, the height of the shield wall portion 110A is 1.3 mm, and the thickness is 0.2 mm. However, it may be other sizes.
(12) Although the case where the shield plate 120 is used for the mobile communication terminal 1000 has been described as an example in the embodiment, it may be used for devices other than the mobile communication terminal.

For example, when there is a digital / analog mixed IC that emits electromagnetic wave noise in a device such as a medical device that is inconvenienced by receiving electromagnetic wave noise at a specific site, the shield plate 120 may be used for this device. Conceivable.
(13) The mobile communication terminal is disposed so as to cover an IC in which a digital circuit and an analog circuit that performs analog signal processing are incorporated, a substrate on which the IC is disposed, and a main surface of the IC. A portable communication terminal comprising a shield plate for electromagnetic noise emitted by the digital circuit of the IC, wherein the shield plate is a region on the main surface of the IC, and when receiving a predetermined electromagnetic wave, the analog circuit of the IC It is good also as a feature that the through-hole is opened in the site | part corresponding to the area | region which reduces the performance of this.

The shield plate provided in the mobile communication terminal having the above-described configuration is provided with a through hole, and the region on the main surface of the IC corresponding to the through hole receives the predetermined electromagnetic wave, and the performance of the analog circuit of the IC is set to the predetermined performance. It has become a more vulnerable area.
By opening a through hole in the shield plate, electromagnetic noise emitted by the digital circuit of the IC is generated in the region of the main surface of the IC corresponding to the through hole of the shield plate through the shield plate covering the IC. Because it does not propagate, the amount of propagation through the shield plate of the electromagnetic noise emitted by the digital circuit of the IC to the area where the performance of the RF circuit is lowered below a predetermined level when receiving a predetermined electromagnetic wave can be suppressed. Thus, there is an effect that it is possible to provide a mobile communication terminal that suppresses a decrease in the performance of the RF circuit from a predetermined performance.
(14) The mobile communication terminal further includes a shield frame erected on the substrate, and the shield frame is transported by chucking the shield frame with a chucking tool and a wall portion surrounding the side peripheral surface of the IC. A chucking flat plate portion to be used when the shield plate is attached to the upper end side of the wall portion, and the chucking flat plate portion is sandwiched between the IC and the shield plate, and the IC It may be characterized in that it is present at a position that covers a part of the main surface of the material and does not cover the region.

Here, the chucking flat plate portion is a plate-like structure that is chucked (sucked) by a chucking tool represented by a suction disk or the like necessary for transporting the shield frame in the assembly process of the mobile communication terminal. A part of the shield frame.
As a result, the area covered by the chucking flat plate portion is the area excluding the area that reduces the performance of the RF circuit below the predetermined performance when receiving a predetermined electromagnetic wave on the main surface of the IC. The electromagnetic wave noise propagating to the antenna can be suppressed, and the wall portion surrounds the IC, whereby the electromagnetic wave noise returning to the antenna can be further suppressed.

Furthermore, since the chucking flat plate portion used in the assembly process of the mobile communication terminal is also used as a shield for suppressing the electromagnetic wave noise propagating from the IC to the shield plate, it is compared with the assembly process of the conventional mobile communication terminal. Thus, there is an effect that the electromagnetic wave noise returning to the antenna can be suppressed without requiring new parts and processes.
(15) A method for specifying a portion of a through-hole to be opened in a shield plate is a through-hole that is disposed so as to cover the main surface of the IC on the substrate and that opens in the shield plate that suppresses transmission of electromagnetic wave noise emitted by the IC. In the method of identifying the part of the IC, an electromagnetic wave application step of applying an electromagnetic wave in a spot manner to each of the plurality of small regions on the main surface of the IC, and each of the plurality of small regions by the electromagnetic wave application step, For each period of applying a predetermined electromagnetic wave, a performance measurement step for measuring the performance of the IC and a determination as to whether or not the predetermined performance is satisfied for each performance of the IC measured in the performance measurement step And the shield corresponding to the small area where it is determined that the performance of the IC is not satisfied every time the performance determination step is negative. Site of, may be characterized by comprising a through-hole portion specifying step of specifying as a part of the through hole.

  As a result, by measuring the IC performance for each small area, the part where the through hole is opened in the shield plate can be specified in units of small areas. Therefore, the shield can be accurately controlled according to the size of the small area. It has the effect that the part which opens a through-hole in a board can be specified now.

DESCRIPTION OF SYMBOLS 100 Mobile communication terminal housing 110 Shield frame 110A Shield wall part 110B Chucking flat plate part 120 Shield board 130 Digital / analog mixed IC
140 Through-hole 150 Substrate 220 Antenna 1000 Mobile communication terminal

Claims (2)

An IC incorporating a digital circuit and an analog circuit for performing analog signal processing;
A substrate on which the IC is disposed;
A shield plate for electromagnetic noise emitted by the digital circuit of the IC, disposed so as to cover the main surface of the IC ;
A mobile communication terminal comprising a shield frame standing on the substrate ,
The shield plate is a region on the main surface of the IC, and a through hole is opened in a portion corresponding to a first region that reduces the performance of the analog circuit of the IC when receiving a predetermined electromagnetic wave ,
The shield frame has a wall portion that surrounds a side peripheral surface of the IC, and a flat plate portion,
The shield plate is attached to the upper end side of the wall portion,
The flat plate portion is sandwiched between the IC and the shield plate, covers at least a part of the second region that can emit the predetermined electromagnetic wave, and covers the first region, on the main surface of the IC. A mobile communication terminal characterized by being present at a position not present . A shield structure that shields electromagnetic noise emitted from an IC in which a digital circuit and an analog circuit that performs analog signal processing are incorporated ,
A substrate on which the IC is disposed;
A shield plate for electromagnetic noise emitted by the digital circuit of the IC, disposed so as to cover the main surface of the IC ;
A shield frame standing on the substrate ,
The shield plate is a region on the main surface of the IC, and a through hole is opened in a portion corresponding to a first region that reduces the performance of the analog circuit of the IC when receiving a predetermined electromagnetic wave ,
The shield frame has a wall portion that surrounds a side peripheral surface of the IC, and a flat plate portion,
The shield plate is attached to the upper end side of the wall portion,
The flat plate portion is sandwiched between the IC and the shield plate, covers at least a part of the second region that can emit the predetermined electromagnetic wave, and covers the first region, on the main surface of the IC. It is characterized by being present at no position
Shield structure.

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