JP2011249177A - Fuse device and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuse device which is made compact while improving productivity.SOLUTION: A fuse device comprises: a ceramic substrate 1; a temperature fuse part 2 with a heating resistor including a heating resistor 21 and a first temperature fuse element 22; and a second temperature fuse element 31. The heating resistor 21 is provided in the ceramic substrate 1 integrally with the ceramic substrate 1. The first temperature fuse element 22 is provided on the surface of the ceramic surface 1 and is thermally connected to the heating resistor 21. The second temperature fuse element 31 is provided on the surface of the ceramic substrate 1, electrically connected to the first temperature fuse element 22 in series, and is thermally connected to a protection target.

Description

  The present invention relates to a fuse device or the like used for protecting an electronic circuit or the like in an overvoltage state or an overcurrent state.

  There is a thermal fuse device with a heating resistor as a protection device used to shut off an electronic circuit or the like from an electronic circuit or the like when an overvoltage is applied to the electronic circuit or the like to be protected. In addition, when an overcurrent flows through an electronic circuit or the like to be protected and the electronic circuit or the like generates heat due to the overcurrent, a thermal fuse device is used as a protection device used to shut off the electronic circuit or the like from the electronic circuit or the like. There is. Conventionally, these thermal fuse devices with heating resistors and thermal fuse devices have been provided on, for example, a mounting substrate as individually sealed devices.

JP 2009-48849 A

  In recent years, for example, electronic modules used for portable electronic devices and the like are required to be miniaturized. Therefore, in fuse devices used for such electronic modules and the like, a reduction in the area required for mounting is required. Yes. In particular, in order to add both a thermal fuse function with a heating resistor and a thermal fuse function to an electronic module, it is necessary to reduce the occupation area of the thermal fuse part with a heating resistor and the thermal fuse part while improving productivity. is there.

  According to one aspect of the present invention, a fuse device includes a ceramic base, a thermal fuse portion with a heating resistor including a heating resistor and a first thermal fuse element, and a second thermal fuse element. . The heating resistor is provided integrally with the ceramic base inside the ceramic base. The first thermal fuse element is provided on the surface of the ceramic substrate and is thermally coupled to the heating resistor. The second thermal fuse element is provided on the surface of the ceramic substrate, is electrically connected in series to the first thermal fuse element, and is thermally coupled to the protection target.

  According to another aspect of the present invention, a circuit board includes an insulating base, a circuit conductor provided on the insulating base, and a fuse portion provided on the insulating base. The fuse part includes a ceramic layer, a thermal fuse part with a heating resistor including a heating resistor and a first thermal fuse element, and a second thermal fuse element. The heating resistor is provided integrally with the ceramic layer inside the ceramic layer. The first thermal fuse element is provided on the surface of the ceramic layer and is thermally coupled to the heating resistor. The second thermal fuse element is provided on the surface of the ceramic layer, is electrically connected in series to the first thermal fuse element, and is thermally coupled to the protection target.

  According to one aspect of the present invention, a fuse device includes a thermal fuse portion with a heating resistor including a heating resistor and a first thermal fuse element, and a first electrically connected in series to the first thermal fuse element. 2 and the heat generating resistor is provided inside the ceramic substrate, so that it can have a temperature fuse function with a heat generating resistor and a temperature fuse function, and can be miniaturized. Productivity can be improved.

  According to another aspect of the present invention, a circuit board includes a thermal fuse portion with a heating resistor including a heating resistor and a first thermal fuse element, and a first electrically connected in series to the first thermal fuse element. 2 thermal fuse elements are included, and the heating resistor is provided inside the ceramic layer, thereby providing a thermal fuse function with a heating resistor and a thermal fuse function, and reducing the occupied portion of the fuse portion. Thus, a circuit board with improved productivity can be realized.

1 shows a perspective view of a fuse device according to a first embodiment of the present invention. FIG. 2 shows an exploded perspective view of the fuse device shown in FIG. 1. FIG. 3 is a longitudinal sectional view taken along line AA of the fuse device shown in FIG. 2. 4 schematically shows heat conduction in the fuse device shown in FIG. 3. It is a circuit diagram which shows the usage example of the fuse apparatus shown by FIG. The longitudinal cross-sectional view of the fuse apparatus in the 2nd Embodiment of this invention is shown. FIG. 7 schematically shows heat conduction in the fuse device shown in FIG. 6. The perspective view of the fuse apparatus in the 3rd Embodiment of this invention is shown. The perspective view of the electronic module containing the circuit board in the 4th Embodiment of this invention is shown.

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

(First embodiment)
As shown in FIGS. 1 to 3, the fuse device according to the first embodiment of the present invention includes a ceramic base 1, a thermal fuse portion 2 with a heating resistor provided in the ceramic base 1, and a temperature. The fuse part 3 is included.

  In FIG. 1, the fuse device is mounted on an xy plane in a virtual xyz space. In FIG. 1, the upward direction means the positive direction of the virtual z axis. In FIG. 1, the ceramic substrate 1 is shown in a partially transparent state for the purpose of showing the internal structure and the bottom surface structure of the fuse device. In FIG. 1, the internal structure of the fuse device and a part of the lower surface structure are indicated by dotted lines.

  The ceramic substrate 1 includes a first ceramic layer 11 to a third ceramic layer 13 each having a flat plate shape. The second ceramic layer 12 is provided on the first ceramic layer 11, and the third ceramic layer 13 is provided on the second ceramic layer 12. The first ceramic layer 11, the second ceramic layer 12, and the third ceramic layer 13 are integrally formed by firing. The ceramic substrate 1 has a hollow portion 14 provided corresponding to the thermal fuse portion 2 with a heating resistor. The ceramic substrate 1 is substantially made of alumina, for example.

  A thermal fuse portion 2 with a heating resistor is provided on the ceramic substrate 1 and includes a heating resistor 21 and a first thermal fuse element 22.

  The heating resistor 21 generates Joule heat for fusing the first thermal fuse element 22 when, for example, an overvoltage is applied to the electronic circuit. The heating resistor 21 is provided inside the ceramic base 1 and is integrally formed with the ceramic base 1 by firing. The heating resistor 21 is provided between the second ceramic layer 12 and the third ceramic layer 13. The heating resistor 21 is provided on the lower surface of the third ceramic layer 13 and is electrically connected to terminals 4 and 5 provided on the lower surface of the ceramic substrate 1. The heating resistor 21 includes a conductive material such as tungsten (W), molybdenum (Mo), or manganese (Mn). The heating resistor 21 is provided between the first thermal fuse element 22 and the hollow portion 14, and is at least partially exposed to the hollow portion 14.

  As schematically shown in FIG. 4, the Joule heat generated by the heating resistor 21 is conducted to the lower surface of the ceramic substrate 1 because the ceramic substrate 1 has the hollow portion 14. With respect to being conducted to the first thermal fuse element 22. Therefore, the fuse device is reduced with respect to the loss of Joule heat generated by the heating resistor 21. The hollow portion 14 is preferably in a reduced pressure state including a vacuum state. Since the hollow portion 14 is in a reduced pressure state, the conduction of Joule heat from the heating resistor 21 to the lower surface of the ceramic substrate 1 is reduced. In FIG. 4, a block arrow by a solid line schematically shows conduction of Joule heat from the heating resistor 21 to the first thermal fuse element 22, and a block arrow by a broken line shows from the heating resistor 21 to the ceramic substrate 1. The conduction of Joule heat to the lower surface of the substrate is schematically shown.

  Referring to FIGS. 1 to 3 again, the first thermal fuse element 22 is provided on the surface of the ceramic substrate 1 and is thermally coupled to the heating resistor 21. “Thermal coupling to the heating resistor 21” means that the heating resistor 21 and the first temperature fuse element 22 function integrally as a temperature fuse with a heating resistor. The heat transfer path from the heating resistor 21 to the first temperature fuse element 22 is provided so that the first temperature fuse element 22 is blown by the Joule heat generated by the above. The first thermal fuse element 22 is provided on the upper surface of the third ceramic layer 13 and is located immediately above the heating resistor 21. The first thermal fuse element 22 is electrically connected to the terminal 4 via a conductor pattern 71 provided on the upper surface of the ceramic substrate 1. An example of the material of the first thermal fuse element 22 is a low melting point fusible alloy.

  The thermal fuse portion 3 includes a second thermal fuse element 31. The second thermal fuse element 31 is provided on the surface of the ceramic substrate 1 and is electrically connected in series to the first thermal fuse element 22. The second thermal fuse element 31 is provided on the upper surface of the third ceramic layer 13. The second thermal fuse element 31 is electrically connected to the first thermal fuse element 22 via a conductor pattern 72 provided on the upper surface of the ceramic substrate 1 and provided on the upper surface of the ceramic substrate 1. It is electrically connected to the terminal 6 provided on the lower surface of the ceramic substrate 1 through the conductor pattern 73. An example of the material of the second thermal fuse element 31 is a low melting point fusible alloy.

  The second thermal fuse element 31 is reduced in terms of thermal coupling with the heating resistor 21 by the recess 17 provided on the upper surface of the ceramic substrate 1. The recess 17 is preferably deeper than the height position where the heating resistor 21 is provided.

  The fuse device further includes a flux member 81 covering each of the first thermal fuse element 22 and the second thermal fuse element 31 and an enclosing member 82 covering the flux member 81. 1 and 2, the flux member 81 and the enclosing member 82 are omitted for the purpose of showing the structure on the upper surface of the ceramic substrate 1. The enclosing member 82 includes, for example, a resin material or a ceramic material.

  With reference to FIG. 5, the usage example of the fuse apparatus in this embodiment is demonstrated. In FIG. 5, the fuse device in this embodiment is shown as a fuse circuit 53. The fuse circuit 53 is electrically connected to the power source 51, the electronic circuit 52 to be protected, and the overvoltage detection circuit 54. In FIG. 5, the arrow by a dotted line has shown thermal coupling | bonding.

  The fuse circuit 53 includes a thermal fuse portion 2 with a heating resistor and a thermal fuse portion 3. The thermal fuse portion 2 with a heating resistor includes a heating resistor 21 and a first thermal fuse element 2. The thermal fuse portion 3 includes a second thermal fuse element 31. The first thermal fuse element 22 is thermally coupled to the heating resistor 21. The second thermal fuse element 31 is thermally coupled to the electronic circuit 52 to be protected. The heating resistor 21 is electrically connected to the terminals 4 and 5. The terminal 4 is electrically connected to the power source 51. The first thermal fuse element 22 is electrically connected to the terminal 4 and is connected in series to the second thermal fuse element 31. The second thermal fuse element 31 is electrically connected to the terminal 6. Terminal 6 is electrically connected to node 501.

  The overvoltage detection circuit 54 is electrically connected to the nodes 501 and 502 and the terminal 5. The overvoltage detection circuit 54 operates when a voltage greater than the rating is applied to the electronic circuit 52. The overvoltage detection circuit 54 includes a Zener diode 541 and a transistor 542. Zener diode 541 has a cathode electrically connected to node 501 and an anode electrically connected to transistor 542 through a resistor. Transistor 542 has a base electrically connected to the Zener diode through a resistor, an emitter electrically connected to terminal 5, and a collector electrically connected to node 502.

  When the voltage applied to the electronic circuit 52 becomes equal to or higher than the breakdown voltage of the Zener diode 541, a base current flows through the transistor 542, and a collector current flows through the transistor 542 in accordance with the base current. When the collector current flows, Joule heat is generated in the heating resistor 21, and the first thermal fuse element 22 is blown by the Joule heat. The electronic circuit 52 is disconnected from the power source 51 by the first thermal fuse element 22 being blown. When an overcurrent flows through the electronic circuit 52 and the electronic circuit generates more heat than specified, the second thermal fuse element 31 that is thermally coupled to the electronic circuit 52 is blown. The electronic circuit 52 is disconnected from the power source 51 by the second thermal fuse element 31 being blown.

  The fuse device in the present embodiment includes a thermal fuse portion 2 with a heating resistor including a heating resistor 21 and a first thermal fuse element 22, and a second electrically connected in series to the first thermal fuse element 22. The thermal fuse element 31 is included, and the heating resistor 21 is embedded in the ceramic substrate 1, whereby the thermal fuse function with the heating resistor and the thermal fuse function can be provided, and the size can be reduced. Productivity can be improved.

  In the fuse device according to the present embodiment, the ceramic base 1 has the hollow portion 14, and the heating resistor 21 is provided between the hollow portion 14 and the first thermal fuse element 22. In the fuse device in the embodiment, the loss of Joule heat generated by the heating resistor 21 is reduced. Therefore, the fuse device in the present embodiment is improved with respect to the fusing characteristics of the first thermal fuse element 22 in the overvoltage state.

  In the fuse device of the present embodiment, the heating resistor 21 is exposed in the hollow portion 14, so that the fuse device in the present embodiment relates to conduction of Joule heat from the lower surface of the heating resistor 21 to the ceramic substrate 1. It is reduced and the fusing characteristics of the first thermal fuse element 22 in the overvoltage state are improved.

(Second Embodiment)
A fuse device according to a second embodiment of the present invention will be described with reference to FIG. In the fuse device according to the second embodiment, a configuration different from the fuse device according to the first embodiment is a position where the hollow portion 14 is provided in the ceramic substrate 1. About another structure, it is the same as that of the fuse apparatus in 1st Embodiment.

  The hollow portion 14 is provided below the heating resistor 21 so as to sandwich the heating resistor 21 between the first thermal fuse element 22 and the hollow portion 14, and is separated from the heating resistor 21.

  As schematically shown in FIG. 7, Joule heat generated by the heating resistor 21 is conducted to the lower surface of the ceramic substrate 1 by providing the hollow portion 14 below the heating resistor 21. And is improved with respect to conduction to the first thermal fuse element 22. Therefore, the fuse device is reduced with respect to the loss of Joule heat generated by the heating resistor 21. In FIG. 7, a block arrow by a solid line schematically shows the conduction of Joule heat from the heating resistor 21 to the first thermal fuse element 22, and a block arrow by a broken line shows from the heating resistor 21 to the ceramic substrate 1. The conduction of Joule heat to the lower surface of the substrate is schematically shown.

  The hollow portion 14 is preferably in a reduced pressure state including a vacuum state. Since the hollow portion 14 is in a reduced pressure state, the conduction of Joule heat from the heating resistor 21 to the lower surface of the ceramic substrate 1 is reduced.

(Third embodiment)
A fuse device according to a third embodiment of the present invention will be described with reference to FIG. In the fuse device according to the third embodiment, the structure different from the fuse device according to the first embodiment is the structure of the surface of the ceramic substrate 1. The ceramic substrate 1 has an upper surface including a plurality of recesses 15 and 16. About another structure, it is the same as that of the fuse apparatus in 1st Embodiment.

  The first thermal fuse element 22 is provided in the recess 15, and the second thermal fuse element 31 is provided in the recess 16. In FIG. 8, the enclosing member 82 is indicated by a broken line in a transparent state for the purpose of showing the structure on the upper surface of the ceramic substrate 1.

  In the fuse device of the present embodiment, the first thermal fuse element 22 is provided in the recess 15, and the second thermal fuse element 31 is provided in the recess 16. The fuse device is reduced with respect to the loss of heat conducted to the first thermal fuse element 22 or the second thermal fuse element 31, and the fusing characteristics of the first thermal fuse element 22 or the second thermal fuse element 31 are reduced. Has been improved.

  In the fuse device of the present embodiment, it is also possible to apply the technology relating to the hollow portion 14 in the fuse device of the second embodiment described with reference to FIG.

(Fourth embodiment)
A circuit board according to a fourth embodiment of the present invention will be described with reference to FIG. The circuit board in the present embodiment is used for an electronic module including the electronic components 81 and 82.

  The circuit board has a circuit conductor provided on the insulating base 83 and a fuse portion 90 embedded in the insulating base 83. The exemplary insulating base 83 is substantially made of ceramics. The circuit conductor electrically connects the electronic components 81 and 82. The fuse portion 90 is electrically connected to an electronic circuit including the electronic components 81 and 82 through a circuit conductor. In FIG. 9, the electronic component 81 is partially omitted for the purpose of showing the structure of the insulating base 83.

  The fuse portion 90 is provided below the electronic component 81. The fuse part 90 includes a ceramic layer 91, a temperature fuse part 92 with a heating resistor provided in the ceramic layer 91, and a temperature fuse part 93. In FIG. 9, the fuse part 90 is shown in a partially transparent state for the purpose of showing the internal structure, and a part of the internal structure is shown by a dotted line.

  The thermal fuse portion 92 with the heating resistor is provided in the ceramic layer 91, and includes the heating resistor 921 and the first thermal fuse element 922.

  The heating resistor 921 is embedded in the ceramic layer 91 and is integrally formed with the ceramic layer 91 by firing.

  The first thermal fuse element 922 is provided on the surface of the ceramic layer 91 and is thermally coupled to the heating resistor 921. “Thermal coupling to the heating resistor 22” means that the heating resistor 921 and the first thermal fuse element 922 function integrally as a thermal fuse with a heating resistor. The heat transfer path from the heating resistor 921 to the first thermal fuse element 922 is provided so that the first thermal fuse element 922 is blown by the Joule heat generated by the above. The first thermal fuse element 922 is located immediately above the heating resistor 921. The first thermal fuse element 922 is electrically connected to a conductor pattern 971 provided on the upper surface of the ceramic layer 91. An example of the material of the first thermal fuse element 922 is a low melting point fusible alloy.

  The thermal fuse portion 93 includes a second thermal fuse element 931. The second thermal fuse element 931 is provided on the surface of the ceramic layer 91 and is electrically connected in series to the first thermal fuse element 922. The second thermal fuse element 931 is electrically connected to the first thermal fuse element 922 via a conductor pattern 972 provided on the upper surface of the ceramic layer 91 and provided on the upper surface of the ceramic layer 91. The conductor pattern 973 is electrically connected. An example of the material of the second thermal fuse element 931 is a low melting point fusible alloy.

  The circuit board according to the present embodiment includes a heating fuse-provided temperature fuse portion 92 including a heating resistor 921 and a first thermal fuse element 922, and a first thermal fuse element 922 electrically connected in series. And the thermal resistor 921 is embedded in the ceramic layer 91, thereby providing a thermal fuse function with a thermal resistor and a thermal fuse function, and reducing the occupied portion of the fuse portion 90. Thus, a circuit board with improved productivity can be realized.

  In the circuit board according to the present embodiment, the technology relating to the hollow portion 14 in the fuse device according to the first embodiment described with reference to FIGS. 1 to 3 can be applied.

  In the circuit board of this embodiment, it is also possible to apply the technology relating to the hollow portion 14 in the fuse device of the second embodiment described with reference to FIG.

  In the circuit board of this embodiment, it is also possible to apply the technology relating to the recesses 15 and 16 in the fuse device of the third embodiment described with reference to FIG.

  As described above, the circuit board substantially made of ceramics has been described. However, in the present embodiment, the circuit board is formed inside or on the surface of the insulating base substantially made of an organic material. Including one provided with the fuse device shown in any of the embodiments.

DESCRIPTION OF SYMBOLS 1 Ceramic base | substrate 14 Concavity 2 Thermal fuse part 21 with a heating resistor 21 Heating resistor 22 1st thermal fuse element 3 Thermal fuse part 31 2nd thermal fuse element 4 Terminal 5 Terminal 6 Terminal

Claims (6)

A ceramic substrate;
A heating resistor and a first thermal fuse element, wherein the heating resistor is provided integrally with the ceramic base inside the ceramic base, and the first thermal fuse element is formed on the surface of the ceramic base. A thermal fuse portion with a heating resistor provided and thermally coupled to the heating resistor;
A fuse provided on the surface of the ceramic substrate and electrically coupled in series to the first thermal fuse element and thermally coupled to the object to be protected; apparatus.   2. The fuse device according to claim 1, wherein the ceramic base has a hollow portion, and the heating resistor is disposed between the hollow portion and the first thermal fuse element.   The fuse device according to claim 2, wherein the heating resistor is exposed in the hollow portion.   The fuse device according to claim 2, wherein the hollow portion is in a reduced pressure state.   2. The fuse device according to claim 1, wherein the first thermal fuse element and the second thermal fuse element are respectively disposed in recesses provided on a surface of the ceramic substrate. An insulating substrate;
A circuit conductor provided on the insulating substrate;
A fuse portion provided on the insulating base,
The fuse part is
A ceramic layer;
A heating resistor and a first thermal fuse element, wherein the heating resistor is provided integrally with the ceramic layer in the ceramic layer, and the first thermal fuse element is formed on the surface of the ceramic layer. A thermal fuse portion with a heating resistor provided and thermally coupled to the heating resistor;
And a second thermal fuse element that is provided on the surface of the ceramic layer and is electrically connected in series to the first thermal fuse element and is thermally coupled to a protection target. Circuit board.

Images