JP5142573B2 - Electronics - Google Patents

Description

  The present invention relates to an electronic device. In particular, the present invention relates to a printed circuit board on which an integrated circuit element such as an IC, CPU, ASIC or the like is mounted and a metal plate facing the printed circuit board. In particular, static electricity or high voltage noise is applied to the metal plate. It is related to the structure in the situation.

As a conventional metal plate facing the printed circuit board, there is one in which the printed circuit board is covered with a metal plate for the purpose of shielding electromagnetic noise generated from the printed circuit board and external electromagnetic noise (for example, patents). Reference 1). In addition, a metal plate is used as a heat radiating plate of a circuit element (for example, see Patent Document 2), and is used for fixing a printed circuit board (for example, see Patent Document 3).
JP 2001-291986 A JP-A-11-145656 JP 2006-133650 A

  However, although the above-described conventional example is effective for electromagnetic wave shielding (shielding), there are the following problems.

  (1) In order to ground the shielding metal frame (shell) of the device external connection connector to the chassis, the metal frame of the connector is electrically connected to a metal plate facing the printed circuit board. At this time, if electrostatic noise is applied to the metal shell of the connector, the potential of the metal plate facing the substrate may fluctuate abruptly, and as a result, the integrated circuit element electrostatically coupled to the metal plate may cause malfunction. is there.

  (2) When static electricity is applied to a metal plate facing the outside of the device, the inside of the integrated circuit element that is electrostatically coupled to the metal plate may cause a malfunction as in (1).

  The present invention has been made paying attention to the above points, and it is an object of the present invention to provide an electronic device capable of preventing the malfunction of an integrated circuit element due to noise such as static electricity applied to a metal plate. To do.

  In order to solve the above problems, an electronic apparatus of the present invention has the following configuration.

(1) an electronic circuit board on which an integrated circuit element is mounted; a connection part mounted on the electronic circuit board and electrically connected to the integrated circuit element to connect an external device and the integrated circuit element; A metal plate that is opposite to the surface of the electronic circuit board opposite to the surface on which the integrated circuit element is mounted, and that is electrically connected to the electronic circuit board and the connection portion; electronic apparatus comprising a Turkey which have a said integrated circuit opening of the outer shape or size of the elements in a position corresponding to the mounting position of the integrated circuit element mounted on an electronic circuit board.

  According to the present invention, the opening corresponding to the shape of the integrated circuit element is provided, so that the metal plate and the integrated circuit element are not electrostatically coupled, and the integrated circuit element is not affected by noise such as static electricity applied to the metal plate. The occurrence of malfunction can be prevented. Further, since the electrostatic coupling force between the metal plate and the internal semiconductor of the integrated circuit element is weakened, the malfunction of the integrated circuit element due to noise such as static electricity applied to the metal plate can be prevented.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  1 to 3 are diagrams for explaining the present embodiment. FIG. 1 is an exploded perspective view of a printed board mounting portion according to the present embodiment. FIG. 2 is an explanatory diagram of a main part of the printed circuit board according to the present embodiment. FIG. 3 is a perspective view for explaining the positional relationship between the printed circuit board and the substrate holding sheet metal according to this embodiment. In FIG. 1, 101 is an electrophotographic printer (electronic device), 102 is a drive gear, 103 is an exterior cover (exterior member), 104 is a USB connector hole, 105 is a printed circuit board (electronic circuit board), and 106 is a CPU (integrated circuit). Element). Also, 107 is a USB connector (connection means), 108 is a substrate holding sheet metal (metal plate), 109 is a sheet metal opening (opening), and 110 is a screw. In FIG. 2, 201 is a board screw hole, 202 is a soldering portion of the metal shell of the USB connector 107, 203 is an FG pattern for connecting the metal shell of the USB connector 107 to the board holding metal plate 108 which is a frame ground (FG). 204 are signal patterns.

  An electrophotographic printer 101 has an electrophotographic engine unit (not shown), and a part of the mechanism is a drive gear 102. The drive gear 102 and the printed circuit board 105 are fixed by screws 110 through a substrate holding sheet metal 108. These members are fixed and covered with an exterior cover 103 to obtain a product. The printed circuit board 105 is equipped with a USB connector 107 and a CPU 106, and constitutes an interface for communication with a personal computer (hereinafter referred to as a personal computer). The printed circuit board 105 is connected to an engine control circuit (not shown) by wiring (not shown). The USB connector 107 is covered with a metal shell (a metal frame for shielding) that is a shield cover, and this metal shell is soldered to the FG pattern 203 of the printed circuit board 105 by a metal shell soldering portion 202. The FG pattern 203 extends to the board screw hole 201 and is electrically connected to the board holding metal plate 108 by using a screw 110. The substrate holding sheet metal 108 is electrically connected to the electrophotographic printer 101 by being fixed to the electrophotographic printer 101 made of sheet metal with screws 110. Therefore, the metal shell of the USB connector 107 is electrically connected to the FG of the electrophotographic printer 101. A signal line of the USB connector 107 is connected to the CPU 106 by a signal line pattern 204. In FIG. 2, wirings and parts other than these are omitted.

  The substrate holding sheet metal 108 has a sheet metal opening 109. As indicated by a broken line in FIG. 3, this is substantially the same size as the outer shape of the CPU 106, the size of the same shape (outer shape), and substantially the same position in the top view of the printed board 105. The sheet metal opening 109 may have a substantially similar shape larger than the CPU 106. That is, in order to eliminate the electrostatic coupling between the CPU 106 and the substrate holding sheet metal described below, the shape of the sheet metal opening 109 may be larger than the outer shape of the CPU 106.

  The substrate holding metal plate 108 has a function of holding the printed circuit board 105 and fixing it to the electrophotographic printer 101 while avoiding the drive gear 102, and also has a function of FG wiring of the metal shell of the USB connector 107 described above. Yes. Here, when static electricity charged on the human body of the user is applied to the USB connector 107, a discharge path is formed to the electrophotographic printer 101 through the FG pattern 203 and the substrate holding sheet metal 108. At this time, the entire electric potential of the substrate holding metal plate 108 changes suddenly due to the current flowing at a stroke by the energy of static electricity. At this time, if the sheet metal opening 109 is not present, the CPU 106 may be electrostatically coupled with the substrate holding sheet metal 108 to cause the CPU 106 to malfunction. However, the sheet metal opening 109 of the present invention eliminates the electrostatic coupling between the CPU 106 and the substrate holding sheet metal 108, thereby preventing malfunction due to static electricity.

  A part of the exterior of the electrophotographic printer 101 is formed of sheet metal. In this state, when static electricity is applied to the exterior sheet metal of the electrophotographic printer 101, the potential of the substrate holding sheet metal 108 may change abruptly in some cases. Also in this case, the CPU 106 is not affected by static electricity by providing the sheet metal opening 109 according to the present invention.

  In the present embodiment, the package of the CPU 106 is shown as QFP (Quad Flat Package). In addition, it can be applied to any package such as SOP (Small Outline Package), DIP (Dual Inline Package).

  FIG. 4 to FIG. 6 are diagrams for explaining the present embodiment, and parts different from the first embodiment will be described. FIG. 4 is a diagram for explaining the positional relationship between the printed circuit board and the substrate holding sheet metal according to this embodiment. FIG. 5 is a diagram illustrating the CPU according to the present embodiment. 6A and 6B are diagrams for explaining the shape of the sheet metal opening according to the present embodiment, in which FIG. 6A is a view showing a case of a round opening, FIG. 6B is a view showing a case of an oval opening, and FIG. These are figures which show the case of a polygonal opening. FIG. 6D is a view showing the case of the slit opening, FIG. 6E is a view showing the case of the slit opening, and FIG. 6F is a view showing the case of the mesh opening. In FIG. 4, 401 is a small sheet metal opening. In FIG. 5, reference numeral 501 denotes a semiconductor chip (internal semiconductor) inside the CPU 106, and 502 denotes a lead frame of the CPU 106. The CPU 106 is electrically connected from the lead frame 502 to the semiconductor chip 501 by a gold or aluminum wire (not shown).

  As shown in FIG. 4, by setting the size of the metal plate opening 401 of the substrate holding metal plate 108 to the size of the semiconductor chip 501, it is possible to minimize the metal plate opening 401 without causing malfunction due to static electricity.

  Further, as schematically shown in FIG. 6, the sheet metal opening 401 may be as follows as long as the size of the sheet metal opening is equal to or larger than the size of the semiconductor chip 501 (indicated by a broken line in the drawing). That is, a round opening 601 (FIG. 6A), an elliptic opening 602 (FIG. 6B), a polygon opening 603 (FIG. 6C), and a cut opening 604 (FIG. 6D). )). Further, a plurality of small openings such as a slit opening 605 (FIG. 6E), a mesh opening 606 (FIG. 6F), and the like may be used.

  Also in this embodiment, the sheet metal openings 401 and 601 to 606 eliminate the electrostatic coupling between the semiconductor chip 501 of the CPU 106 and the substrate holding sheet metal 108, and can prevent malfunction due to static electricity.

  7 to 8 are diagrams for explaining the present embodiment, and different portions from the first embodiment will be described. FIG. 7 is a vertical sectional view for explaining attachment of a printed circuit board on which the USB connector and the CPU according to the present embodiment are mounted on the same surface. FIG. 8 is a vertical sectional view for explaining the positional relationship between the printed circuit board and the substrate holding metal plate according to this embodiment. In FIG. 7, reference numeral 701 denotes a printed board on which the CPU 106 is mounted on the surface of the USB connector 107. In FIG. 8, reference numeral 801 denotes a substrate holding sheet metal that holds the printed circuit board 105 from the exterior cover 103 side, contrary to the substrate holding sheet metal 108. In the substrate holding metal plate 801, the portion of the foot 802 to be assembled to the electrophotographic printer 101 is further widened, and a hole 803 is opened so that the tip portion of the USB connector 107 protrudes. The foot 802 has a function as a cover of the USB connector 107 by filling the gap between the USB connector hole 104 and the USB connector 107 with the hole 803.

  As shown in FIG. 7, the positional relationship between the CPU 106 and the sheet metal opening 109 may be on the back side of the printed circuit board 701 or on the front side. Further, as shown in FIG. 8, the positional relationship between the printed circuit board 105 and the substrate holding metal plate 801 may face either side of the exterior cover 103. Further, the substrate holding sheet metal 108 may be a sheet metal inside the apparatus as in the first embodiment, or may be a part of the exterior cover 103 like the substrate holding sheet metal 801 in the present embodiment.

  Also in this embodiment, the sheet metal opening 109 eliminates the electrostatic coupling between the CPU 106 and the substrate holding sheet metal 801, thereby preventing the malfunction due to static electricity.

  In the first to third embodiments, the semiconductor integrated circuit element is the CPU 106, but the present invention can be applied regardless of the type or field of semiconductor such as ASIC and LSI.

It is a disassembled perspective view of the printed circuit board attachment part which concerns on Example 1 of this invention. It is principal part explanatory drawing of the printed circuit board which concerns on Example 1 of this invention. It is a perspective view explaining the positional relationship of the printed circuit board which concerns on Example 1 of this invention, and a board | substrate holding metal plate. It is a figure explaining the positional relationship of the printed circuit board which concerns on Example 2 of this invention, and a board | substrate holding metal plate. It is a figure explaining CPU which concerns on Example 2 of this invention. It is a figure explaining the shape of the sheet-metal opening part concerning Example 2 of this invention, (a) is a figure which shows the case of a round opening, (b) is a figure which shows the case of an elliptical opening, (c) Is a diagram showing a case of a polygonal opening, (d) is a diagram showing a case of a slit opening, (e) is a diagram showing a case of a slit opening, and (f) is a diagram showing a case of a mesh opening. is there. It is a vertical sectional view explaining attachment of a printed circuit board on which a USB connector and a CPU according to Example 3 of the present invention are mounted on the same surface. It is a vertical sectional view explaining the positional relationship between the printed circuit board and the substrate holding metal plate according to the third embodiment of the present invention.

Explanation of symbols

101 Electrophotographic printer (electronic equipment)
105 Printed circuit board (electronic circuit board)
106 CPU (Integrated Circuit Element)
107 USB connector (connection means)
108 Substrate holding sheet metal (metal plate)
109 Sheet metal opening (opening)
203 FG pattern 401 Small sheet metal opening 501 Semiconductor chip (internal semiconductor)

Claims (1)

An electronic circuit board having integrated circuit elements mounted thereon;
A connection part mounted on the electronic circuit board and electrically connected to the integrated circuit element to connect the external circuit and the integrated circuit element;
A surface of the electronic circuit board opposite to the surface on which the integrated circuit element is mounted, and a metal plate electrically connected to the electronic circuit board and the connection part,
The metal plate is characterized by a Turkey which have a said electronic circuit and the integrated circuit opening of the outer shape or size of the elements in a position corresponding to the mounting position of the IC element mounted on a substrate Electronics.

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