JP4330138B2 - Shield case with heat generation safety countermeasure function and electronic device using the same - Google Patents

Description

  The present invention relates to a shield case, and more particularly to a shield case with a heat generation safety countermeasure function suitable for use in a portable electronic device and an electronic device using the shield case.

Electronic parts that dislike the influence of electromagnetic waves and electronic parts that emit electromagnetic waves are often used while being shielded. There exists (patent document 1) as an example of such a shield structure. However, in this shield structure, no means for detecting the heat generation of the electronic component is taken.
Electronic parts that generate heat, such as power amplifiers used in wireless units such as mobile phones, are required to take safety measures against heat in order to detect abnormal heat generation of electronic parts and avoid the dangers associated with abnormal heat generation.

Japanese Utility Model Publication No. 61-173198

  Therefore, the present invention provides a shield case with a heat generation safety measure that forms a resistance thin film in a shield case that shields an electronic component, and that can detect an abnormality caused by heat generation of the electronic component that the shield case wraps by a change in resistance of the resistance thin film, and the shield It is to provide an electronic device using a case.

  According to the present invention, there is provided a shield case with a heat generation safety measure function including a resin mold member, a shield member formed on the surface of the resin molding member, and a resistance thin film member formed on a portion of the surface of the resin mold member. Thus, a shield case with a heat generation safety function capable of detecting heat generation by changing the resistance value of the resistance thin film member is obtained.

  According to the embodiment of the present invention, four resistive thin film members are formed on the surface of the resin mold member.

  According to the embodiment of the present invention, the shield member and the resistive thin film member are formed on the inner surface of the resin mold member.

According to one aspect of the present invention, the shield member is formed of a metal thin film. According to another aspect, the shield member and the resistance thin film member are formed of a conductive paint.
Further, according to the present invention, a shield case including a shield member formed on the surfaces of the resin mold member and the resin molding member and a resistance thin film member formed on a portion of the surface of the resin mold member, and a circuit on which an electronic component is mounted A shield structure for an electronic component is obtained in which a substrate and a shield case are disposed on the circuit board so as to cover the electronic component and are electrically connected to a grounding conductive thin film disposed in parallel to the surface of the circuit board.

  Further, according to the present invention, the electronic component comprises a main circuit, an electronic component, a shield member formed on the surface of the resin mold member and the resin molding member, and a resistance thin film member formed on a portion of the surface of the resin mold member. An electronic device including a shield case that covers the device, and includes means for detecting a change in resistance of the resistance thin film member, and means for stopping the supply of power to the main circuit when the resistance exceeds a predetermined reference. Electronic equipment is obtained.

  According to the present invention, the main circuit, the electronic component, the resin mold member, the shield member formed on the surface of the resin molding member, and the four resistance thin film members formed on one part of the surface of the resin mold member, An electronic device including a shield case covering an electronic component, wherein the balance between the four resistive thin film members connected to the four sides of the Wheatstone bridge and the Wheatstone bridge is more than a predetermined reference In this case, an electronic device including means for stopping the supply of power to the main circuit is obtained.

  Further, according to another aspect of the present invention, the main circuit, the electronic component, the shield member formed on the surface of the resin mold member and the resin molding member, and the four resistors formed on a part of the surface of the resin mold member A Wheatstone bridge circuit in which four resistive thin film members are connected so as to be four sides of a Wheatstone bridge, and a pair of power supplies for the Wheatstone bridge circuit. A power source connected to the supply terminal; means for detecting an equilibrium state of the Wheatstone bridge connected to a pair of terminals of the Hortonstone bridge; and means for stopping the supply of the previous power source to the main circuit by the output of the detection means Can be obtained.

  Furthermore, according to the present invention, a casing of a portable electronic device including a shield member formed on the surfaces of the resin mold member and the resin molding member and a resistive thin film member formed on a portion of the surface of the resin mold member, An electronic device comprising: a main circuit built in the body; means for detecting a change in resistance of the resistive thin film member; and means for stopping the supply of power to the main circuit when the resistance exceeds a predetermined reference. available.

  In the present invention, a shield member is formed on the surface of the resin mold member to provide a shielding effect and a resistive thin film is formed on a part of the surface of the resin mold member. Can be detected by a change in the resistance of the conductive thin film. Further, since the resistive thin film is formed on the surface of the resin mold, a special space for the arrangement is not newly required, and a heat generation safety circuit can be mounted in a small space. Furthermore, since the heat generation can be detected by covering the electronic component which is the heat generation source with the shield case, the heat generation can be detected near the heat generation source.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a partially cutaway perspective view showing the shield case of the first embodiment. In the figure, a shield case 100 includes wide conductive thin films 121, 122, 123, 124, and 125 and thin strip-shaped conductive thin films 131, 132, 125 on the inner surface of a resin-molded mold 110 made of an insulating material. 133 and 134 are formed. The wide conductive thin film is for providing an electromagnetic wave shielding function, and the four thin thin conductive films are used as resistors, and are used for safety measures of the shield case. .

  These thin films are formed by attaching a conductive paint to the entire inner surface of the mold or by depositing a conductive material, and then removing the thin film to a depth reaching the inner surface of the insulating mold 110 to obtain grooves 141A, 141B, 142A, 142B, 143A and 143B, 144A and 144B are formed to form a plurality of wide conductive thin films and thin strip-shaped conductive thin films that are electrically separated from each other. The conductive thin film may be formed of the same material as that for the shield and the resistance portion. However, since the shield portion has as little electrical resistance as possible, the resistance portion needs to provide a certain resistance value. A small metal thin film may be used, and a conductive thin film having a higher resistivity may be used for the resistance portion.

  Inside the shield case 100, an electronic component that generates an electromagnetic wave or an electronic component that should be protected from the influence of the electromagnetic wave is disposed.

Referring to FIG. 2, there is shown a circuit board 200 which has an excellent connection effect when combined with a shield case and is electrically connected to detect the influence on the shield case due to heat generated by electronic components contained in the shield case. Has been. On the insulating substrate 210, shield connection pads 220 to 227 and resistance connection electrode pads 230 to 237 are provided. Furthermore, the conductor wiring 240 that connects the electrode pads 230 and 231, the conductor wiring 241 that connects the electrode pads 232 and 233, the conductor wiring 242 that connects the electrode pads 237 and 234, and the electrode pads 236 and 235 on the substrate 210. Conductor wiring 243 is formed to connect the two.

  3A and 3B show the AA cross section and the BB cross section of FIG. As is clear from FIG. 3A, a ground (GND) conductive layer 310 is disposed on the lower surface of the substrate 210, and the shield connection pads 220 and 224 are electrically connected to the metal pins 321 and 3220, respectively. Has been. Further, as shown in FIG. 3B, the shield connection pads 227, 226, and 225 are electrically connected to the ground conductive layer by metal pins 325, 323, and 322. The resistance connection electrode pad 236 is connected to the ground conductive layer 310 by a metal pin 324. Instead of metal pins, via holes may be used for electrical connection by applying copper foil or gold plating.

  In the shield case 100 shown in FIG. 1, electronic components are mounted on a circuit board before being placed on the circuit board 200. FIG. 4 is a plan view showing a mounted circuit board 400 in which electronic components are mounted on the circuit board 200, and for example, a power amplifier 410 that generates noise is mounted thereon. Wiring and lead terminals for the power amplifier are omitted.

  Referring to FIG. 5, the shield case 100 is disposed so as to cover the electronic component mounted circuit board 400. The arrangement state of the shield case 100 with respect to the circuit board is shown in FIG. 6 showing a CC cross section of FIG. That is, the end portions 131A, 132A, 133A and 134A of the resistance thin film portion of the shield case are electrically connected to the resistance electrode pads 237, 236, 235 and 235 of the circuit board, and the shielding thin film Each of the parts 121, 122, 123, 124 and 125 is electrically connected to the shielding pads 220, 227, 226, 225 and 224. These connections are made by applying cream solder on the pads and then melting the solder. Similarly, the thin film portion for resistance and the thin film portion for shielding that extend on the opposite side surfaces of the shield case are connected to the pads at the positions facing the pads described above on the substrate.

  Referring to FIG. 7, the resistance thin film portions 131, 132, 133 and 134 provided on the inner surface of the resin molding of the package 100 are combined with the wiring of the circuit board to form a Wheatstone bridge, and the resistance thin film portion is a bridge. It becomes resistance of 4 sides. The resistance values of these four sides are R1, R2, R3 and R4. The connection point A between the resistor R1 (resistance thin film portion 131) and the resistor R2 (resistance thin film portion 132) and the connection point between the resistor R3 (resistance thin film portion 134) and the resistor R4 (resistance thin film portion 133) of this bridge. A positive terminal and a negative terminal of the battery 710 are respectively connected to B, and the negative terminal is grounded. A galvanometer 720 is connected to a connection point C between the resistors R1 and R3 and a connection point D between the resistors R2 and R4. Connection points A, C, and D correspond to A, C, and D in FIG. 5, respectively, and connection point B corresponds to a grounding conductive layer.

  The Wheatstone bridge is balanced when the relationship of R1 · R4 = R2 · R3 is established between the resistance values of the four sides, and the current value of the galvanometer becomes zero. It may be designed so that each resistance value is the same, and the bridge is balanced in that state.

  In a balanced state, the current flowing through the galvanometer is zero, the control unit receives the output of the galvanometer, closes the switch 740, and current is supplied from the battery 710 to the main circuit 750 via the switch. The main circuit is a main part of the circuit, and operates with power supplied from the battery. The main circuit also includes electronic components in the shield case.

  When the electronic components in the shield case generate heat, the shield case also generates heat, and the resin mold constituting the shield case is deformed, and the resistive thin film on the mold is deformed or disconnected. Deformation or disconnection of the resistive thin film occurs in the resistive thin film that is closest to the place where the electronic component generates heat most. For this reason, the resistance values constituting the four sides of the bridge change and the balance is lost, and current flows through the galvanometer. By detecting the current flowing through the galvanometer, the control unit 730 opens the switch and stops the supply of current from the battery 710 to the main circuit 750. For this reason, it is possible to prevent the power supply to the electronic component from being stopped and becoming important.

  Since the shield case of the present invention is provided with a shield thin film member and a resistive thin film on a resin mold, it has a function of a safety device against abnormal heat generation of the electronic component as well as a shield function of the electronic component.

  This embodiment of the present invention is a shield case in which a shield member is formed on the surface of the resin mold member to provide a shielding effect and a resistive thin film is formed on a part of the surface of the resin mold member. Can be detected by a change in resistance of the resistive thin film. Moreover, since the resistive thin film is formed on the surface of the resin mold, a special space for the arrangement is not newly required.

  Further, this embodiment of the present invention is a shield case in which a conductive thin film for shielding and a resistance thin film serving as a resistance of the four sides of the Wheatstone bridge are formed in a resin mold case by electrically separating them. Abnormal heat generation of the electronic component arranged in the case can be detected by a change in the resistance value of the resistive thin film of the shield case, and the power supply to the main circuit can be stopped.

  In this embodiment, the connection of the resistive thin film constituting the Wheatstone bridge is performed on the substrate, but it may be performed on a resin mold.

  FIG. 8 is a schematic view showing a second embodiment of the present invention. In the first embodiment, in order to form the resistive thin film on the four sides of the Wheatstone bridge on the inner surface of the resin mold case, the thin film of the shield portion is divided into a plurality of parts, but in the second embodiment, a simpler safety device is provided. Provide a shielding case.

  In the figure, reference numeral 900 denotes a shield case, and reference numeral 910 denotes a part of the shielding thin film applied to the inner surface of the resin mold, which is separated into a thin strip-like resistance thin film. Although a perspective view of the shield case is omitted, for example, a thin resistive thin film is formed on the shield case having the shape shown in FIG. 1, and the other thin film portion is a shield thin film. This single thin film for resistance is connected to both ends of the battery 710 via pads on the circuit board. The current flowing through this resistor is monitored by the detection resistor 920. By monitoring this current, the resistance value of the resistor 910 can be monitored. The comparison circuit 930 inverts a control signal output to the control unit 940 when the resistance value of the thin film resistor exceeds a predetermined value compared with a reference resistance value provided in advance in the comparison circuit, and opens the switch 950. Stop supplying power to the main circuit.

  In the case of the shield case of the second embodiment, since the resistive thin film formed thereon is in the form of a single strip, the connection state to the pads on the circuit board changes. As the connection state, it is sufficient if the wiring can take the circuit configuration of FIG. The resistance value of the resistive thin film changes greatly due to a change in the shape of the thin film resistor due to abnormal heat generation of the electronic components in the shield case, or the cutting of the resistive part, and the value of the current flowing therethrough changes significantly. Can be detected and the abnormalities can be dealt with.

  Since the shield case of this embodiment is also provided with a shield thin film member and a resistive thin film on a resin mold, it has a function of a safety device against abnormal heat generation of the electronic component as well as a shield function of the electronic component.

  This embodiment of the present invention is a shield case in which a shield member is formed on the surface of the resin mold member to provide a shielding effect and a resistive thin film is formed on a part of the surface of the resin mold member. Can be detected by a change in resistance of the resistive thin film. Moreover, since the resistive thin film is formed on the surface of the resin mold, a special space for the arrangement is not newly required.

In this embodiment, since only one strip-like resistive thin film has to be formed, the shield case can be easily created. Also, the wiring can be simplified as compared with the first embodiment.
In Examples 1 and 2 described above, the resistance thin film is described as detecting a change in the resistance value due to deformation or cutting depending on the temperature. A change in value may be used.

It is a partially cutaway perspective view of the shield case of the first embodiment of the present invention. It is a top view of the circuit board used for the 1st example of the present invention. It is AA sectional drawing and BB sectional drawing of FIG. It is a top view of the circuit board which mounted the electronic component of the 1st Example of the present invention. It is a top view of the state which covered and fixed the electronic component of the circuit board of the 1st Example of this invention with the shield case. It is CC sectional drawing of FIG. 1 is a block diagram of a first embodiment of the present invention showing a mechanism for monitoring deformation of a shield case due to abnormal heat generation of an electronic component. FIG. 5 is a block diagram of a first embodiment of the present invention, showing a mechanism for monitoring deformation of a shield case due to abnormal heat generation of an electronic component.

Explanation of symbols

100 Shield Case 110 Resin Molds 121, 122, 123, 124, 125 Shielding Thin Films 132, 133, 134, 135 Resistance Thin Films 131A, 132A, 133A, 134A Resistance Thin Film Ends 141A, 141B, 142A, 142B, 143A, 143B, 144A, 144B Separation groove 200 Circuit board 210 Substrate 220, 221, 222, 223, 224, 225, 226, 227 Shield thin film pad
230, 231, 232, 233, 234, 235, 236, 237 Resistance pad 410 Electronic component 710 Battery 720 Galvanometer 730, 940 Control unit 740 Switch 750 Main circuit 930 Comparison circuit

Claims (4)

A shield case comprising a shield member formed on the surface of the resin mold member and a resistance thin film member formed on a portion of the surface of the resin mold member;
An electronic component covered with the shield case;
An electronic device including a main circuit ,
Means for detecting a change in resistance of the resistive thin film member;
Means for stopping the supply of power to the main circuit when the resistance exceeds a predetermined reference. A shield case comprising a shield member formed on the surface of the resin mold member and four resistance thin film members formed on a portion of the surface of the resin mold member;
An electronic component covered with the shield case;
An electronic device including a main circuit ,
A circuit in which the four resistive thin film members are connected to form four sides of the Wheatstone bridge;
And an electronic device including means for stopping the supply of power to the main circuit when the balance of the Hortonstone bridge is more than a predetermined reference. A shield case comprising a shield member formed on the surface of the resin mold member and four resistance thin film members formed on a portion of the surface of the resin mold member;
An electronic component covered with the shield case;
An electronic device including a main circuit ,
A Wheatstone bridge circuit in which the four resistive thin film members are connected to form four sides of the Wheatstone bridge;
A power source connected to a pair of power supply terminals of the Wheatstone bridge circuit; and means for detecting an equilibrium state of the Wheatstone bridge connected to a pair of terminals of the Wheatstone bridge;
Means for stopping the supply of the power to the main circuit by the output of the detection means. A housing comprising a shield member formed on the surface of the resin mold member and a resistance thin film member formed on a portion of the surface of the resin mold member;
A main circuit built in the housing;
Means for detecting a change in resistance of the resistive thin film member;
Means for stopping the supply of power to the main circuit when the resistance exceeds a predetermined reference.

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