JP5294353B2 - Electromagnetic shielding structure - Google Patents

Description

  The present invention relates to an electromagnetic wave shielding structure.

  In a mobile device such as a mobile phone, a plurality of printed boards may be used. In order to reduce the size of a portable device, a plurality of printed circuit boards may be arranged in a stacked manner. Electronic components are mounted on the plurality of printed boards. Electronic components may generate electromagnetic waves. In order to shield electromagnetic waves, an electromagnetic shielding structure is used.

  FIG. 1 is a cross-sectional view schematically showing an example of an electromagnetic wave shielding structure. The electromagnetic wave shield structure 109 shown in FIG. 1 is provided in the wireless terminal 100. The electromagnetic wave shield structure 109 includes a main substrate 101, a sub substrate 106, a shield case frame 103, and a shield case lid 104. An electronic component group 102 is mounted on the upper surface of the main substrate 101. The shield case frame 103 is provided to shield electromagnetic waves generated by the electronic component group 102 and is disposed on the upper surface of the main substrate 101 so as to cover the electronic component group 102. A maintenance opening is provided on the top surface of the shield case frame 103. The shield case lid 104 is disposed on the shield case frame 103 so as to cover the maintenance opening. The sub board 106 is disposed on the shield case lid 104. The sub-board 106 is affixed to the shield case lid 104 with a double-sided tape 105. An electronic component group 110 is mounted on the upper surface of the sub-board 106. The sub board 106 and the main board 101 are electrically connected via a cable 107. According to the electromagnetic wave shielding structure 109, the electromagnetic wave emitted from the electronic component group 102 provided on the main board 101 is shielded by the shield case frame 103 and the shield case lid 104.

  FIG. 2 is a cross-sectional view showing another example of the electromagnetic shielding structure. This electromagnetic wave shield structure 109 is provided with a shield case 108. The shield case 108 is disposed on the upper surface of the sub-board 106 so as to cover the electronic component group 110 mounted on the sub-board 106. The other points are the same as in the example shown in FIG. According to the electromagnetic wave shield structure 109 shown in FIG. 2, even when the electronic component group 110 on the sub-board 106 emits an electromagnetic wave, the shield case 108 shields the electromagnetic wave.

  A related technique is described in Patent Document 1 (Japanese Patent Laid-Open No. 2002-353660). In Patent Document 1, a control circuit block includes a first circuit board on which an electrical component is mounted, and a shield case made of a rectangular frame-shaped metal plate attached on the first circuit board and having an upper surface opened. In addition, it is described that the upper surface opening portion of the shield case is closed and the mounted electrical component is constituted by a second circuit board that is attached by fixing with screws so that the electrical component is positioned in the shield case.

  Another related technique is described in Patent Document 2 (Japanese Patent Laid-Open No. 2006-147917). In Patent Document 2, an electrical shield is disposed on a substrate so as to surround the electrical component, and a perforated shield case having a maintenance opening on a surface facing the substrate is disposed at a position facing the opening of the perforated shield case. The plate-shaped wireless terminal component having conductivity and the hole-shaped shield case side surface of the plate-shaped component member having conductivity are attached to the surface of the shield case side, and the half-facing surface is opened when the wireless terminal is assembled. A shield structure for a wireless terminal having a conductive sheet material in close contact with the periphery of the opening of the shield case is described.

  Still another related technique is described in Patent Document 3 (Japanese Patent Laid-Open No. 2007-67279). In Patent Document 3, a first printed wiring board, a circuit chip having a bottom surface attached to the first printed wiring board, a circuit chip attached to the first printed wiring board and covering the side surface of the circuit chip are disclosed. A shielding frame that surrounds the chip and has an opening provided at a position corresponding to the top surface of the circuit chip, and a shielding pattern is formed on the surface facing the top surface of the circuit chip, and is laminated on the first printed wiring board. A shield structure including the second printed wiring board is disclosed.

  Still another related technique is described in Patent Document 4 (Japanese Patent No. 3853769). In Patent Document 4, an electromagnetic shield includes a first electronic component arranged on a printed circuit board and a second electronic component mounted on a flexible substrate and arranged three-dimensionally with respect to the first electronic component. An electronic component shielding structure is disclosed. The electronic component shield structure includes a first shield case that forms at least a part of a shield space for electromagnetically shielding the first electronic part and has an opening in a part of the wall surface, and an engagement means. A second shield case that is detachably attached to the first shield case and covers the second electronic component and the opening in a state of being attached to the first shield case. A hinge portion is provided between both the first shield case and the second shield case, and is formed in a cantilever shape that is elastically deformed and electrically connected between the two members in an elastically deformed state.

  Still another related technique is described in Patent Document 5 (Japanese Utility Model Publication No. 62-193783). In Patent Document 5, in which a sub printed circuit wiring board mounted with an electrical component is mounted opposite to a main printed circuit wiring board mounted with an electrical component, a shield case is mounted on the main printed wiring board and the shield case is attached. A printed circuit wiring board mounting structure is disclosed in which a sub printed circuit wiring board is fixed in close contact with the back side of a detachably mounted lid.

JP 2002-353660 A JP 2006-147917 A JP 2007-67279 A Japanese Patent No. 3853769 Japanese Utility Model Publication No. 62-193783

  In the example shown in FIGS. 1 and 2, it is necessary to provide a shield case lid 104 in order to close the top surface of the shield case frame 103. That is, the number of parts increases and the number of assembly steps also increases. Further, the thickness of the shield case cover 104 and the double-sided tape 105 increases the thickness of the entire shield structure, which is disadvantageous from the viewpoint of miniaturization.

  On the other hand, in the device described in Patent Document 1 (Japanese Patent Laid-Open No. 2002-353660), the upper surface opening of the shield case is closed by the second circuit board. The second circuit board is fixed with screws. In Patent Document 1, it is not necessary to use the shield case lid 104. However, it is unclear whether the second circuit board has a function of shielding electromagnetic waves. Moreover, since it fixes with a bis | screw, a clearance gap will arise between a shield case and a 2nd circuit board, and electromagnetic waves may leak through a clearance gap.

  Therefore, the subject of this invention is providing the electromagnetic wave shield structure which can suppress the increase in a number of parts and can prevent the leakage of electromagnetic waves reliably.

  Note that Patent Document 2 (Japanese Patent Laid-Open No. 2006-147917) discloses that a flat sheet-shaped component is provided with a conductive sheet material that adheres to the periphery of the opening of the shield case. However, it is not clear how the conductive sheet is closely attached to the periphery of the opening of the shield case, and no contrivance for reliably preventing leakage of electromagnetic waves is disclosed.

  Japanese Patent Application Laid-Open No. 2007-67279 discloses that a second printed wiring board on which a shield pattern is formed contacts a shield frame. However, no device for reliably preventing leakage of electromagnetic waves is disclosed. That is, when the second printed wiring board is simply in contact with the shield frame, a gap or the like may be generated between the shield frame and the second printed wiring board, and electromagnetic waves may leak. There is.

  In Patent Document 4 (Patent No. 3853769), a first shield case is attached on a printed circuit board, a flexible substrate is disposed on the first shield case, and a second shield case is disposed on the flexible substrate. This is disclosed. It is necessary to use two shield cases, which is disadvantageous from the viewpoint of the number of parts. Also, no particular consideration is given to electromagnetic waves leaking through a gap formed between the shield case and the printed circuit board. Moreover, since it is necessary to use a 2nd shield case, thickness and weight will become large.

  Further, in Patent Document 5 (Japanese Utility Model Laid-Open No. 62-193783), a main printed circuit wiring board and a sub printed circuit wiring board are arranged in a shield case. In order to arrange two printed circuit wiring boards in the shield case, it is necessary to use a large case as the shield case, which is disadvantageous from the viewpoint of miniaturization.

  The shield structure according to the present invention has a main board having a first electronic component group mounted on the upper surface, a side surface and a top surface, and is disposed on the upper surface of the main board so as to cover the first electronic component group. And a conductive shielding case frame, a sub board disposed on the top surface of the shielding case frame, and a sub board fixing frame for fixing the sub board on the shielding case frame. An opening is provided on the top surface of the shield case frame. The sub-board is disposed so as to close the opening. The sub-board has a ground plane. The sub-substrate fixing frame has a frame shape and is bent so as to contact the outer peripheral portion of the upper surface of the sub-substrate and the outer side surface of the shield case frame on the inner side.

  According to this invention, the first electronic component group is covered with the shield case frame. The electromagnetic wave emitted by the first electronic component group is shielded by the shield case frame. Further, the opening provided on the top surface of the shield case frame is closed by the sub-board. Since the sub-plane is provided with the ground plane, the electromagnetic wave is also prevented from leaking from the opening. That is, the shield case frame does not need to be configured to cover the sub-board, and the thickness of the electromagnetic wave shield structure can be reduced. Moreover, it is not necessary to use a lid for closing the opening, and an increase in the number of parts can be suppressed.

  In addition, according to the present invention, the sub-board fixing frame has a frame shape and is bent so as to be in contact with the outer peripheral portion of the upper surface of the sub-board and the outer side of the side surface of the shield case frame. The sub board is fixed by the sub board fixing frame. Therefore, even when a gap is generated between the sub board and the shield case frame, electromagnetic waves leaking through the gap are shielded by the sub board fixing frame. That is, electromagnetic wave leakage is reliably prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the electromagnetic wave shield structure which can suppress the increase in a number of parts and can prevent the leakage of electromagnetic waves reliably is provided.

It is sectional drawing which shows an example of an electromagnetic wave shield structure schematically. It is sectional drawing which shows the other example of an electromagnetic wave shield structure. It is sectional drawing which shows schematically the portable terminal provided with the electromagnetic wave shield structure which concerns on 1st Embodiment. It is sectional drawing which shows an example of a structure of the edge part of a sub board | substrate. It is sectional drawing which shows roughly a part of electromagnetic wave shield structure which concerns on the modification of 1st Embodiment. It is sectional drawing which shows roughly the electromagnetic wave shield structure which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 3 is a cross-sectional view schematically showing the mobile terminal 1 provided with the electromagnetic wave shielding structure according to the present embodiment. As shown in FIG. 3, the electromagnetic wave shielding structure 15 is disposed in the casing of the mobile terminal 1.

  The electromagnetic wave shield structure 15 includes a main board 2, a sub board 5, a shield case frame 13, and a sub board fixing frame 7.

  A first electronic component group 3 is mounted on the upper surface of the main substrate 2. The first electronic component group 3 includes, for example, an integrated circuit, a transistor, and a capacitor. The main board 2 is provided with a wiring group (not shown), and the wiring group is connected to the first electronic component group 3. The wiring group provided on the main board 2 includes ground wiring (not shown) that is grounded. Further, on the upper surface of the main board 2, main board terminals 9 connected to the wiring group are provided.

  The shield case frame 13 is provided to shield electromagnetic waves radiated from the first electronic component group 3. The shield case frame 13 has a side surface 16 and a top surface 17. The shield case frame 13 is attached on the upper surface of the main board 2 so as to cover the first electronic component group 3. The shield case frame 13 has conductivity, and is made of, for example, metal. The shield case frame 13 is connected to a ground wiring provided on the main board 2 by soldering. That is, the shield case frame 13 is grounded. The main board ground terminal 9 is not covered by the shield case frame 13. Further, the top surface 17 of the shield case frame 13 is provided with a maintenance opening.

  The sub-board 5 is disposed on the top surface 17 of the shield case frame 13 so as to close the opening for maintenance. A ground plane 6 is provided on the sub-board 5. The ground plane 6 is a layer in which a conductor is provided on the entire surface. The ground plane 6 is provided in the inner layer of the sub-board 5. However, the ground plane 6 may be provided on the surface layer of the sub-board 5. The ground plane 6 is exposed on the lower surface of the sub-board 5 at the outer periphery. The exposed portion of the ground plane 6 is in contact with the shield case frame 13 and is grounded via the shield case frame 13. Hereinafter, this point will be described in detail with reference to FIG.

  FIG. 4 is a cross-sectional view showing an example of the configuration of the end portion of the sub-board 5. In the example shown in FIG. 4, the ground plane 6 is provided in the inner layer of the sub-board 5. In the outer peripheral portion of the sub-board 5, the insulating layer on the ground plane 6 is deleted, and the ground plane 6 is exposed on the lower surface of the sub-board 5. The sub-board 5 is in contact with the shield case frame 13 at the exposed portion of the ground plane 6. By adopting such a configuration, the ground plane 6 and the shield case frame 13 can be electrically connected, and the ground plane 6 can be grounded. Thus, by providing the ground plane 6 on the sub-board 5, it is possible to prevent electromagnetic waves radiated from the first electronic component group 3 from leaking through the opening.

  As shown in FIG. 3, the second electronic component group 4 is mounted on the upper surface of the sub-board 5. A sub board terminal 8 is provided on the upper surface of the sub board. The sub board terminal 8 is connected to the main board terminal 9 via the cable 10. Thereby, the wiring group provided on the sub-board 5 is connected to the wiring group provided on the main board 2.

  The sub board fixing frame 7 is provided to fix the sub board 5 on the shield case frame 13. The sub-board fixing frame 7 is made of metal and has conductivity. The sub substrate fixing frame 7 has a frame shape. The sub substrate fixing frame 7 is bent so as to contact the outer peripheral portion of the upper surface of the sub substrate 5 and the side surface of the shield case frame 13 on the inner side. Thus, the sub board 5 is sandwiched between the top surface 17 of the shield case frame 13 and the sub board fixing frame 7 at the outer peripheral portion. Thereby, the sub-board 5 is fixed. Note that the end portion of the sub-board 5 is covered with the sub-board fixing frame 7 all around and is not exposed. Moreover, the sub board | substrate fixed frame 7 is attached to the edge part of the sub board | substrate 5 so that attachment or detachment is possible.

  In the electromagnetic wave shield structure 15 according to the present embodiment, the first electronic component group 3 is disposed in a space surrounded by the shield case frame 13 and the sub substrate 5. The shield case frame 13 is grounded via the main board 2. Further, the ground plane 6 provided on the sub-board 5 is grounded via the shield case frame 13. Therefore, the electromagnetic waves radiated from the first electronic component group 6 are shielded by the shield case frame 13 and the sub board 5. Further, at the time of maintenance, the sub board fixing frame 7 is removed, and the sub board 5 is removed. Thereby, the 1st electronic component group 3 can be exposed and a maintenance can be performed.

  Here, according to the present embodiment, since the ground plane 6 is provided on the sub-board 5, the sub-board 5 functions as a lid for the opening provided on the shield case frame 13. In order to close the opening, it is not necessary to prepare a separate lid, and the number of parts can be reduced. In addition, the thickness and weight required for the lid can be reduced.

  Further, according to the present embodiment, the sub board 5 is fixed by the sub board fixing frame 7. As shown in FIGS. 1 and 2, when the sub-board 5 is fixed using a double-sided tape, it is necessary to remove the double-sided tape during maintenance. Man-hours required for maintenance increase. On the other hand, according to the present embodiment, it is only necessary to remove the sub board fixing frame 7 during maintenance. Since the sub board | substrate 5 can be removed easily, the man-hour required at the time of a maintenance can be reduced.

  Furthermore, according to the present embodiment, the end portion of the sub-board 5 is covered by the sub-board fixing frame 7 over the entire circumference. Since the sub board fixing frame 7 is in contact with the shield case frame 13, it is grounded. Therefore, even when a gap is generated between the sub board 5 and the shield case frame 13, the electromagnetic waves leaking through the gap are shielded by the sub board fixing frame 7. That is, it is possible to reliably prevent leakage of electromagnetic waves emitted by the first electronic component group 6.

  Subsequently, an electromagnetic wave shield structure 15 according to a modification of the present embodiment will be described. FIG. 5 is a cross-sectional view schematically showing a part of the electromagnetic wave shielding structure 15 according to this modification. In this modification, the configuration of the sub-board 5 is changed. About another point, it is the same as that of the above-mentioned embodiment.

  As shown in FIG. 5, in this variation, the sub-substrate 5 is provided with conductive vias 18. The via 18 is connected to the ground plane 6 and is connected to the ground pattern exposed on the upper surface of the sub-board 5. The ground pattern is in contact with the sub-substrate fixing frame 7 on the upper surface of the sub-substrate 5.

  According to this modification, the ground plane 6 is grounded not only through the shield case frame 13 but also through the sub-board fixing frame 7. Therefore, the contact resistance between the ground plane 6 and the main board 2 can be reduced, and the ground plane 6 can be reliably grounded. Thereby, leakage of electromagnetic waves can be prevented more reliably.

(Second Embodiment)
Next, the second embodiment will be described. In the first embodiment, no consideration is given to the electromagnetic waves emitted by the second electronic component group 4 arranged on the sub-board 5. The second electronic component group 4 arranged on the sub-board 5 may also need to shield emitted electromagnetic waves. Therefore, in the present embodiment, a device is devised so that the electromagnetic waves radiated from the second electronic component group 4 are shielded.

  FIG. 6 is a cross-sectional view schematically showing the electromagnetic wave shielding structure 15 according to the present embodiment. In the present embodiment, the second electronic component group 4 is mounted on the lower surface of the sub-board 5. That is, the second electronic component group 4 is disposed in a space surrounded by the shield case frame 13 and the sub board 5. About another point, since the structure similar to 1st Embodiment is employable, detailed description is abbreviate | omitted.

  According to the present embodiment, since the second electronic component group 4 is disposed in the space surrounded by the shield case frame 13 and the sub-board 5, the electromagnetic waves radiated from the second electronic component group 4 are also shielded. Is possible. As shown in FIG. 2, when the second electronic component group 4 is mounted on the upper surface of the sub-board 5, a shield case must be attached so as to cover the second electronic component group 4. On the other hand, according to the present embodiment, it is not necessary to separately prepare a shield case that covers the second electronic component group 4. Therefore, it is possible to suppress the number of parts.

  The present invention has been described above using the first and second embodiments. Note that these embodiments and modifications are not independent, and can be used in combination with each other within a consistent range.

1 Wireless terminal (housing)
2 Main Board 3 First Electronic Component 4 Second Electronic Component 5 Sub Board 6 Ground Plane 7 Sub Board Fixing Frame 8 Sub Board Terminal 9 Main Board Terminal 10 Cable 12 Closed Space 13 Shield Case Frame 15 Electromagnetic Shield Structure 16 Side 17 Top DESCRIPTION OF SYMBOLS 100 Wireless terminal 101 Main board 102 Electronic component 103 Shield case frame 104 Shield case cover 105 Double-sided tape 106 Sub board 107 Cable 108 Shield case 109 Electromagnetic wave shield structure 110 Electronic component group

Claims (5)

A main board having a first electronic component group mounted on the upper surface;
A shield case frame having a side surface and a top surface, disposed on the upper surface of the main substrate so as to cover the first electronic component group, and having conductivity;
A sub-board disposed on the top surface of the shield case frame;
A sub-board fixing frame having conductivity and fixing the sub-board on the shield case frame;
Comprising
The top surface of the shield case frame is provided with an opening,
The sub-board is arranged to close the opening,
The sub-board has a ground plane,
The sub-substrate fixing frame has a frame shape, and is bent to be in contact with the outer peripheral portion of the upper surface of the sub-substrate and the outer side surface of the shield case frame on the inner side. The electromagnetic shielding structure according to claim 1,
A second electronic component group is mounted on the sub-board,
The electromagnetic shielding structure mounted on the lower surface of the sub board so that the second electronic component group is disposed in a closed space formed by the main board, the shield case frame, and the sub board. An electromagnetic wave shielding structure according to claim 1 or 2,
The main board is provided with a ground wiring to be grounded,
The shield case frame is an electromagnetic wave shield structure that is electrically connected to the ground wiring. An electromagnetic wave shielding structure according to any one of claims 1 to 3,
The electromagnetic wave shielding structure, wherein the ground plane is electrically connected to the shield case frame via a contact portion between the sub-board and the shield case frame. The electromagnetic shielding structure according to any one of claims 1 to 4,
The electromagnetic wave shield structure, wherein the ground plane is electrically connected to the sub-substrate fixing frame via a contact portion between the sub-substrate and the sub-substrate fixing frame.

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