JP2009043815A - Protection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection device which is used mainly for a battery cell unit in various types of electronic devices and which can reliably protect an electronic circuit with a simple arrangement. <P>SOLUTION: A heat conductive pattern 10 is provided on the upper surface of a wiring circuit board 1 to extend from the lower surface of a switching element 2 to the inner edge of a through hole 8, a heat conductive resin 9 is coated and formed between the outer periphery of a temperature fuse 5 and the switching element 2, so that heat generated by the switching element 2 can be reliably transmitted to the temperature fuse 5 with less variations, not only from the heat conductive resin 9 but also from the heat conductive pattern 10 having a good thermal conductivity. Consequently, the protection device capable of reliably protecting an electronic circuit can be obtained with a simple arrangement. <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.

  7 is a cross-sectional view of a conventional protective device, and FIG. 8 is a perspective view thereof. In FIG. 7, reference numeral 1 denotes a wiring board having a plurality of wiring patterns (not shown) formed on the upper and lower surfaces, and 2 denotes an FET or transistor. A plurality of terminals 4 of the switching element 2 are mounted and connected to a plurality of lands 3 on the upper surface of the wiring board 1 by soldering, and the switching element 2 is connected to a battery (not shown) via a wiring pattern. And an electronic circuit (not shown) of the device.

  Reference numeral 5 denotes a thermal fuse. The left and right terminals 6 are soldered to the lands 7 and connected between the switching element 2 and the battery, and are attached to the through holes 8 of the wiring board 1 near the left side of the switching element 2. At the same time, a thermal conductive resin 9 such as silicone is applied between the outer periphery of the thermal fuse 5 and the switching element 2 and in the through hole 8 to constitute a protective device.

  Further, when manufacturing such a protective device, first, as shown in the exploded perspective view of FIG. 9, after solder cream (not shown) is printed on the lands 3 and 7 on the upper surface of the wiring substrate 1, 3, the terminal 4 of the switching element 2 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. 11, the through-hole 8 is closed from the back surface of the wiring board 1 with a tape (not shown) or the like, and the thermal conductivity between the inside of the through-hole 8 and its periphery and the switching element 2. After applying the resin 9, as shown in the perspective view of FIG. 12, the thermal fuse 5 is embedded in the thermally conductive resin 9 and the left and right terminals 6 are placed on the lands 7.

  Further, after that, the terminal 6 is soldered to the land 7 by manual work so that a large heat is not applied to the thermal fuse 5, the heat conductive resin 9 is dried, and the tape etc. which closes the back surface of the through hole 8 is peeled off. Thus, the protection device as shown in FIGS. 7 and 8 is completed.

  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 9 and further transmitted to the thermal fuse 5 through the thermal conductive resin 9.

  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 shutting off, the device is prevented from being damaged due to a short circuit or the like.

  Further, by mounting the thermal fuse 5 in the through hole 8 of the wiring board 1, the overall height of the apparatus can be reduced compared to the case where the thermal fuse 5 is placed on the upper surface of the wiring board 1, and the outer periphery of the thermal fuse 5 The heat conductive resin 9 applied between the switching element 2 and the switching element 2 is configured to reliably transmit the heat generated by the switching element 2 to the thermal fuse 5.

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, the thermal fuse 5 is mounted in the through hole 8 of the wiring board 1 so that the overall height of the device can be reduced. Since the heat of the switching element 2 is dissipated from the upper surface and the lower surface of the heat conductive resin 9 applied in the through-hole 8, depending on the conditions in which the device is used, the heat transmission may vary. There was a problem that there was.

  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 provides a thermal conductive pattern extending from the lower surface of the switching element to the inner edge of the through hole on the upper surface of the wiring board, and a thermal conductive resin between the outer periphery of the thermal fuse and the switching element. The protection device is configured by coating and forming, and in addition to the heat conductive resin, the heat generated by the switching element is extended by the heat conductive pattern with good heat conductivity, such as copper, extending from the lower surface of the switching element to the inner edge of the through hole. Therefore, it is possible to obtain a protective device capable of reliably protecting an electronic circuit with a simple configuration.

  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 1 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 substrate 1 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 mounted in the through hole 8 of the wiring board 1 near the left side.

  Further, 10 is a substantially T-shaped heat conduction pattern such as copper foil or silver, and the upper surface of the wiring board 1 extends from the lower surface of the switching element 2 to the through hole 8 as shown in the exploded perspective views of FIGS. And a hollow cylinder portion 10B provided in a through hole shape at the inner edge of the through hole 8.

  The entire surface of the wiring board 1 excluding the heat conduction pattern 10 and the lands 3 and 7 is covered with an insulating layer (not shown) such as polyester or epoxy, and between the outer periphery of the thermal fuse 5 and the switching element 2 and through holes. In 8, a heat conductive resin 9 such as silicone is applied and formed to constitute a protective device.

  When manufacturing such a protective device, first, as shown in the exploded perspective view of FIG. 3, after solder cream (not shown) is printed on the lands 3 and 7 on the upper surface of the wiring substrate 1, The terminal 4 of the switching element 2 is placed on 3 and heated, and the switching element 2 is soldered to the wiring board 1 as shown in the perspective view of FIG.

  At this time, the solder 7 is printed on the lands 7 not on the entire upper surface but on both ends, so that the protrusions 7A are formed on both ends of the upper surface by the solder that is printed and melted and hardened after heating.

  Then, as shown in the exploded perspective view of FIG. 5, the through-hole 8 is closed from the back surface of the wiring board 1 with a tape (not shown) or the like, and the thermal conductivity between the inside of the through-hole 8 and its periphery and the switching element 2. After applying the resin 9, as shown in the perspective view of FIG. 6, the thermal fuse 5 is embedded in the thermally conductive resin 9 and the left and right terminals 6 are placed between the protruding portions 7 </ b> A of the land 7.

  Further, after that, the terminal 6 is soldered to the land 7 by manual work so that a large heat is not applied to the thermal fuse 5, the heat conductive resin 9 is dried, and the tape etc. which closes the back surface of the through hole 8 is peeled off. Thus, the protection device as shown in FIGS. 1 and 2 is completed.

  When the thermal fuse 5 is soldered to the lands 7, the left and right lands 7 have protrusions 7A at both ends as shown in FIG. The thermal fuse 5 can be placed in a state where it is placed between 7A and positioned with little displacement, and the terminal 6 is simply melted with a soldering iron or the like without using new solder. Soldering to the land 7 can be performed.

  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.

  When 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. Is transmitted to the thermal conductive resin 9 and further transmitted to the thermal fuse 5 through the thermal conductive resin 9.

  At the same time, in the present invention, the heat generated by the switching element 2 is also generated from the flat portion 10A of the heat conduction pattern 10 extending to the lower surface of the switching element 2 through the hollow cylinder portion 10B at the inner edge of the through hole 8. Go to 5.

  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.

  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 9, and at the same time, the thermal fuse of the thermal conductive pattern 10 having good thermal conductivity such as copper. Heat is also transmitted from the hollow cylinder portion 10B close to 5, so that the thermal fuse 5 is surely blown at a predetermined temperature.

  That is, even when the gap between the switching element 2 and the thermal fuse 5 and the conditions under which the device is used vary and the heat of the switching element 2 is dissipated somewhat from the upper surface of the thermal conductive resin 9 and the lower surface of the through hole 8, the switching is performed. By the heat conduction pattern 10 extending from the lower surface of the element 2 to the inner edge of the through hole 8, the heat generation of the switching element 2 is reliably transmitted to the thermal fuse 5, and the power supply from the battery is surely cut off, so It is configured to prevent damage.

  As described above, according to the present embodiment, the heat conduction pattern 10 extending from the lower surface of the switching element 2 to the inner edge of the through hole 8 is provided on the upper surface of the wiring board 1 and between the outer periphery of the thermal fuse 5 and the switching element 2. By applying and forming the heat conductive resin 9, in addition to the heat conductive resin 9, also the heat conduction pattern 10 having a good heat conductivity such as copper causes the heat generation of the switching element 2 to vary in the temperature fuse 5. Since the information can be reliably transmitted with a small amount, it is possible to obtain a protection device capable of reliably protecting an electronic circuit with a simple configuration.

  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 Same perspective view Cross-sectional view of a conventional protection device Same perspective view Exploded perspective view Same perspective view Exploded perspective view Same perspective view

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wiring board 2 Switching element 3, 7 Land 4, 6 Terminal 5 Thermal fuse 7A Protrusion part 8 Through-hole 9 Thermal conductive resin 10 Thermal conductive pattern 10A Flat part 10B Hollow cylinder part

Claims (1)

A wiring board having a plurality of wiring patterns formed on the upper surface, a switching element for switching the battery power source, and a thermal fuse mounted in a through hole in the vicinity of the switching element. A protective device in which a heat conductive pattern extending to the inner edge of the through hole is provided and a heat conductive resin is applied and formed between the outer periphery of the thermal fuse and the switching element.

Images