JP2009032606A - Protective device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective device principally used for a battery unit of various electronic appliances and capable of securely protecting electronic circuits with a simple configuration. <P>SOLUTION: The protective device with a simple configuration and of less inconsistency in heat conduction as well as capable of securely protecting electronic circuits is provided by: disposing a framed wall portion 13 interconnecting an outer circumference of a thermal fuse 5 and a switching element 2 on an upper surface of a wiring substrate 11; and coating a heat conductive resin 8 within the framed wall portion 13, so that the heat conductive resin 8 can be formed only on required portions between the outer circumference of the thermal fuse 5 and the switching element 2 and so that heat generated in the switching element 2 can be efficiently transferred to the thermal fuse 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a protection device mainly used for battery units of various electronic devices.

  In recent years, portable devices such as notebook computers and video cameras are equipped with a rechargeable battery, and various operations have been performed using this battery power source when being carried. Also in battery units used for these devices, There is a need for an inexpensive and reliable electronic circuit protection.

  Such a conventional protection device will be described with reference to FIGS.

  FIG. 7 is a perspective view of a conventional protective device. In FIG. 7, reference numeral 1 denotes a wiring board on which a plurality of wiring patterns (not shown) are formed on the upper and lower surfaces, and 2 denotes a switching element such as an FET or a transistor. A plurality of terminals 4 of the switching element 2 are mounted and connected to the plurality of lands 3 on the upper surface of the substrate 1 by soldering, and the switching element 2 is connected to a battery (not shown) or an electronic circuit of a device (Fig. (Not shown).

  5 is a thermal fuse, and the left and right terminals 6 are soldered to the lands 7, connected between the switching element 2 and the battery, and placed on the upper surface of the wiring board 1 near the left side of the switching element 2, A thermal conductive resin 8 such as silicone is applied between the outer periphery of the switching element 2 and the thermal fuse 5 to constitute a protective device.

  When manufacturing such a protective device, first, as shown in the exploded perspective view of FIG. 8, after the cream solder is printed on the lands 3 and 7 on the upper surface of the wiring substrate 1, the switching element 2 is applied to the lands 3. The terminal 4 is placed and heated, and the switching element 2 is soldered to the wiring board 1 as shown in the perspective view of FIG.

  Then, as shown in the exploded perspective view of FIG. 10, the thermal conductive resin 8 is applied to the left side surface of the switching element 2 and the left upper surface of the wiring substrate 1, and then the thermal fuse 5 is placed in the thermal conductive resin 8. The terminal 6 is soldered to the land 7 by manual work, and the heat conductive resin 8 is dried to complete the protective device as shown in FIG.

  In the above configuration, when the device is carried, power is supplied from the battery to the electronic circuit through the switching element 2 to perform various operations of the device, and when the battery is charged, the switching element 2 is used. The battery is charged from a charger or the like through the switching element 2.

  In the event that such a device is operated or a battery is charged, if a short circuit occurs and an overcurrent flows through the switching element 2, the overcurrent causes the switching element 2 to generate heat, and this heat Is transmitted to the thermal conductive resin 8 and further transmitted to the thermal fuse 5 through the thermal conductive resin 8.

  When the overcurrent flows to some extent and the heat transmitted to the thermal fuse 5 reaches a predetermined temperature or more, the thermal fuse 5 is melted and the power supply from the battery to the switching element 2 and the electronic circuit is cut off. The

  That is, the thermal fuse 5 connected between the battery and the switching element 2 detects the heat generation of the switching element 2 due to overcurrent or the like, and when this heat exceeds a predetermined temperature, the power supply from the battery is turned off. By blocking, it is configured to prevent damage to the device due to a short circuit or the like.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 11-330665

  However, in the above-described conventional protection device, when the thermal conductive resin 8 is applied to the upper surface of the wiring board 1 on the left side of the switching element 2 at the time of manufacturing the device, the thermal conductive resin 8 that has a certain degree of viscosity but is in a liquid state is used. Since it spreads on the upper surface of the wiring board 1, the heat conductive resin 8 of the dried and completed device has a large area.

  For this reason, the amount of use of the heat conductive resin 8 is increased, and when the heat generated by the switching element 2 is transmitted, heat is also generated between the switching element 2 and the temperature fuse 5 that are originally required, and also in portions other than the outer periphery of the temperature fuse 5. Therefore, depending on the conditions in which the apparatus is used, there is a problem that the heat transmission may vary.

  The present invention solves such a conventional problem, and an object of the present invention is to provide a protection device capable of reliably protecting an electronic circuit with a simple configuration.

  In order to achieve the above object, the present invention has the following configuration.

  According to the first aspect of the present invention, a frame wall portion for connecting the outer periphery of the thermal fuse and the switching element is provided on the upper surface of the wiring board, and a thermally conductive resin is applied and formed in the frame wall portion. The protective device is configured to prevent the thermal conductivity resin from being applied to the unnecessary part of the upper surface of the wiring board by the frame wall, and to the necessary part between the outer periphery of the thermal fuse and the switching element. Only a thermally conductive resin is formed, and the heat generated by the switching element can be efficiently transmitted to the thermal fuse, so that a protection device capable of reliably protecting electronic circuits can be obtained with a simple configuration with little variation in thermal conduction. Has the effect of being able to

  According to a second aspect of the present invention, in the first aspect of the invention, a heat conductive pattern extending from the lower surface of the thermal fuse to the lower surface of the switching element is provided on the upper surface of the wiring board, and a frame wall portion is provided on the upper surface of the heat conductive pattern. In addition to the thermally conductive resin, the heat of the switching element can be transmitted to the thermal fuse by means of the thermal conductive pattern, so there is less variation and the electronic circuit can be reliably protected Have

  As described above, according to the present invention, it is possible to obtain an advantageous effect that it is possible to realize a protective device capable of reliably protecting an electronic circuit with a simple configuration.

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

  In addition, the same code | symbol is attached | subjected to the part of the structure same as the structure demonstrated in the term of background art, and detailed description is simplified.

(Embodiment)
FIG. 1 is a cross-sectional view of a protective device according to an embodiment of the present invention, FIG. 2 is a perspective view thereof, in which 11 is a wiring board such as paper phenol or epoxy containing glass, and copper and the like are provided on the upper and lower surfaces. Thus, a plurality of wiring patterns (not shown) are formed, and a plurality of lands 3 and 7 are provided on the upper surface.

  Reference numeral 2 denotes a switching element such as an FET or a transistor. A plurality of terminals 4 are mounted and connected to a plurality of lands 3 on the upper surface of the wiring board 11 by soldering, and the switching element 2 is connected to a battery (not shown) via the wiring pattern. ) Or an electronic circuit (not shown) of the device.

  Reference numeral 5 denotes a temperature fuse having a substantially cylindrical shape in which a fusible metal is built in a cylinder such as a ceramic. The left and right terminals 6 are soldered to the lands 7 and connected between the switching element 2 and the battery. The switching element 2 is arranged near the left side.

  A substantially T-shaped heat conduction pattern 12 extending from the lower surface of the thermal fuse 5 to the lower surface of the switching element 2 is formed on the upper surface of the wiring board 11. A substantially U-shaped frame wall 13 that connects the outer periphery and the switching element 2 is provided.

  Further, an insulating layer (not shown) such as polyester or epoxy covers the entire surface of the wiring board 11 except for the heat conductive pattern 12 and the lands 3 and 7, and the frame wall portion 13 has a heat conductive resin 8 such as silicone. Is applied to form a protective device.

  When manufacturing such a protective device, first, as shown in the exploded perspective view of FIG. 3, cream solder was printed on the entire surface of the lands 3 and 7 on the upper surface of the wiring board 11 and the upper surface of the outer periphery of the heat conduction pattern 12. Thereafter, the terminal 4 of the switching element 2 is placed on the land 3 and heated, and the switching element 2 is soldered to the wiring board 11 as shown in the perspective view of FIG.

  At this time, the outer periphery of the thermal fuse 5 and the switching element 2 are formed on the outer peripheral upper surface of the substantially T-shaped heat conduction pattern 12 extending from the lower surface of the thermal fuse 5 to the lower surface of the switching element 2 by printed and melt-cured solder. The substantially U-shaped frame wall portion 13 that connects the two is formed on the top surface of the land 7 with protrusions 7A at both ends.

  Then, as shown in the exploded perspective view of FIG. 5, the thermal conductive resin 8 is applied to the left side surface of the switching element 2 and the left frame wall portion 13, and then the thermal fuse 5 is placed in the thermal conductive resin 8. , The terminals 6 are soldered to the lands 7 by manual work, and the thermally conductive resin 8 is dried to complete the protective device as shown in FIGS.

  When the thermal fuse 5 is soldered to the lands 7, the left and right terminals 6 are placed between the protrusions 7A because the protrusions 7A are formed at both ends on the upper surfaces of the left and right lands 7, respectively. Thus, the thermal fuse 5 can be arranged in a state of positioning with little deviation, and the soldering of the terminal 6 to the land 7 can be performed only by melting the protruding portion 7A with a soldering iron or the like without using new solder. It can be performed.

  Moreover, since the frame wall part 13 is formed in the location to which the thermal conductive resin 8 on the left side of the switching element 2 is applied, the liquid thermal conductive resin 8 reaches an unnecessary location on the upper surface of the wiring board 1. The thermal conductive resin 8 is applied and formed only on the necessary area between the outer periphery of the thermal fuse 5 and the switching element 2 simply by applying the thermal conductive resin 8 in the frame wall portion 13 to prevent spreading. It is possible to do that.

  Further, as shown in FIGS. 3 and 4, the frame wall portion 13 is formed by printing cream solder on the upper surface of the outer periphery of the heat conductive pattern 12 at the same time as printing cream solder on the lands 3 and 7. Therefore, it can be easily formed without increasing the number of manufacturing steps.

  In the above configuration, when the device is carried, power is supplied from the battery to the electronic circuit through the switching element 2 to perform various operations of the device, and when the battery is charged, the switching element 2 is used. The battery is charged from a charger or the like through the switching element 2.

  In addition, when an overcurrent flows through the switching element 2 due to a short circuit or the like when operating such a device or charging a battery, the switching element 2 generates heat due to this overcurrent, and this heat Is transmitted to the thermal conductive resin 8 and further transmitted to the thermal fuse 5 through the thermal conductive resin 8.

  When the overcurrent flows to a certain extent, for example, 5A or more, and the heat transmitted to the thermal fuse 5 reaches a predetermined temperature or higher, for example, 135 ° C. or higher, the thermal fuse 5 is blown and The power supply to the switching element 2 and the electronic circuit is cut off.

  At this time, as described above, the upper surface of the wiring board 11 is provided with the substantially U-shaped frame wall portion 13 connecting the outer periphery of the thermal fuse 5 and the switching element 2, and the outer periphery of the thermal fuse 5. Since the thermal conductive resin 8 is applied and formed only at a necessary location between the switching element 2 and the switching element 2, the heat generated by the switching element 2 can be efficiently transmitted to the thermal fuse 5.

  In other words, by forming the heat conductive resin 8 only in a necessary area between the outer periphery of the thermal fuse 5 and the switching element 2 by the frame wall portion 13, heat conduction and heat dissipation to an extra portion can be prevented and heat conduction can be prevented. Thus, the electronic circuit can be surely protected.

  Further, a heat conductive pattern 12 extending from the lower surface of the thermal fuse 5 to the lower surface of the switching element 2 is provided on the upper surface of the wiring substrate 11, and a frame wall portion 13 is formed on the upper surface, whereby in addition to the heat conductive resin 8, Since the heat of the switching element 2 can be transmitted to the thermal fuse 5 also by the conductive pattern 12, the heat generation of the switching element 2 can be transmitted to the thermal fuse 5 more reliably.

  That is, when an overcurrent flows and the switching element 2 generates heat, this heat is transmitted to the thermal fuse 5 through the thermal conductive resin 8 and at the same time, from the thermal conductive pattern 12 having good thermal conductivity such as copper. 5, the thermal fuse 5 is surely blown at a predetermined temperature, and the power supply from the battery is surely cut off, thereby preventing the device from being damaged due to a short circuit or the like.

  Although the heat conduction effect by the heat conduction pattern 12 as described above is lost, when the heat generation of the switching element 2 is transmitted to the thermal fuse 5 only by the heat conductive resin 8, as shown in the exploded perspective view of FIG. Alternatively, a substantially U-shaped wiring pattern 14 extending from the outer periphery of the thermal fuse 5 to the lower surface of the switching element 2 may be provided, and the frame wall portion 13 may be formed on the upper surface by solder.

  As described above, according to the present embodiment, the frame wall portion 13 that connects the outer periphery of the thermal fuse 5 and the switching element 2 is provided on the upper surface of the wiring board 11, and the thermal conductivity is provided in the frame wall portion 13. By applying and forming the resin 8, the heat conductive resin 8 is formed only at a necessary portion between the outer periphery of the thermal fuse 5 and the switching element 2, and heat generated by the switching element 2 is efficiently transmitted to the thermal fuse 5. Therefore, it is possible to obtain a protective device capable of reliably protecting an electronic circuit with a simple configuration and less variation in heat conduction.

  Further, a heat conductive pattern 12 extending from the lower surface of the thermal fuse 5 to the lower surface of the switching element 2 is provided on the upper surface of the wiring substrate 11 and a frame wall portion 13 is formed on the upper surface of the heat conductive pattern 12, thereby providing a heat conductive resin. In addition to 8, the heat conduction pattern 12 can also transfer the heat of the switching element 2 to the thermal fuse 5, so that variation is further reduced and the electronic circuit can be reliably protected.

  The protection device according to the present invention has a simple configuration and can reliably protect an electronic circuit, and is useful for battery units of various electronic devices.

Sectional drawing of the protection apparatus by one embodiment of this invention Same perspective view Exploded perspective view Same perspective view Exploded perspective view Exploded perspective view according to another embodiment A perspective view of a conventional protection device Exploded perspective view Same perspective view Exploded perspective view

Explanation of symbols

2 Switching element 3, 7 Land 4, 6 Terminal 5 Thermal fuse 7A Protrusion 8 Thermal conductive resin 11 Wiring board 12 Thermal conduction pattern 13 Frame wall 14 Wiring pattern

Claims (2)

A wiring board having a plurality of wiring patterns and lands formed on the upper surface, a switching element for switching the battery power source, and a thermal fuse mounted in the vicinity of the switching element. And a protective device in which a frame wall portion is provided to connect the switching element and the thermally conductive resin is applied and formed in the frame wall portion. The protection device according to claim 1, wherein a heat conduction pattern extending from the lower surface of the thermal fuse to the lower surface of the switching element is provided on the upper surface of the wiring board, and a frame wall portion is formed on the upper surface of the heat conduction pattern.

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