JP5550436B2 - Current fuse device and circuit board - Google Patents

Description

  The present invention relates to a current fuse device used for protecting an electronic circuit or the like during an overcurrent and a circuit board including a current fuse portion.

  Some conventional current fuse devices have a conductor pattern for a current fuse element formed on the upper surface of a ceramic substrate by firing. The conductor pattern for a current fuse element is obtained by directly applying a conductor paste on the upper surface of a green sheet for a ceramic substrate and then firing it. Therefore, in the conventional current fuse device, the current fuse element conductor pattern is in contact with the upper surface of the ceramic substrate over the entire length.

JP 2003-151425 A

  In the conventional current fuse device, the current fuse element conductor pattern is in contact with the upper surface of the ceramic substrate over the entire length, so that the conventional current fuse device relates to the loss of Joule heat at the fusing point of the current fuse element conductor pattern. Has a problem. Therefore, the conventional current fuse device has a problem regarding the fusing characteristics in an overcurrent state.

According to one aspect of the present invention, a current fuse device includes a ceramic structure and a conductor pattern for a current fuse element. The ceramic structure includes a base portion having an upper surface including an opening portion of a concave portion, a frame portion provided on the base portion and surrounding the opening portion, and a lid provided on the frame portion. Part. The conductor pattern for current fuse elements is formed on the upper surface of the base portion by firing and is provided so as to straddle the opening. And the recessed part is made into the pressure reduction state.

According to another aspect of the present invention, the circuit board includes a current fuse portion, and the current fuse portion includes a ceramic layer and a current fuse element conductor pattern. The ceramic layer has an upper surface including the opening of the recess. Moreover, it has the some groove part provided so that the said recessed part might be pinched | interposed from both sides in the extension direction of the conductor pattern for current fuse elements. The conductor pattern for current fuse elements is formed on the upper surface of the ceramic layer by firing and is provided so as to straddle the opening.

  In the current fuse device according to one aspect of the present invention, the conductor pattern for the current fuse element is formed on the upper surface of the base portion by firing and is provided so as to straddle the opening of the base portion. The current fuse device of one aspect of the invention is reduced with respect to the loss of Joule heat at the fusing location of the conductor pattern for the current fuse element, and improved with respect to the fusing characteristics in an overcurrent state.

  In the circuit board according to another aspect of the present invention, the conductor pattern for the current fuse element is formed on the upper surface of the ceramic layer by firing and is provided so as to straddle the opening of the ceramic layer. The circuit board according to another aspect is reduced with respect to the loss of Joule heat at the fusing location of the conductor pattern for the current fuse element, and is improved with respect to the fusing characteristics in an overcurrent state.

1 shows a perspective view of a current fuse device according to a first embodiment of the present invention. FIG. 2 shows an exploded view of the current fuse device shown in FIG. 1. FIG. 2 is a longitudinal sectional view taken along line AA of the current fuse device shown in FIG. 1. 2 shows a method of manufacturing the current fuse device shown in FIG. It is a figure explaining the manufacturing method shown by FIG. The exploded view of the current fuse apparatus in the 2nd Embodiment of this invention is shown. 7 shows another example of the current fuse device shown in FIG. 6. The perspective view of the electronic module containing the circuit board in the 3rd 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 in the first embodiment of the present invention includes a ceramic structure 1 and a current fuse element conductor pattern 2 provided in the ceramic structure 1. And terminals 3 and 4 provided on the lower surface of the ceramic structure 1. 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 structure 1 is shown in a partially transparent state for the purpose of showing the internal structure. In FIG. 1, a part of the internal structure is indicated by a broken line.

  The ceramic structure 1 includes a base body portion 11, a frame body portion 12 provided on the base body portion 11, and a lid body portion 13 provided on the frame body portion 12. The ceramic structure 1 includes a cavity portion 14 that is provided between the base body portion 11 and the lid body portion 13 and that is positioned inside the frame body portion 12.

  The base portion 11 includes a ceramic material and has a flat plate shape. The exemplary base portion 11 is substantially made of alumina. The base portion 11 has an upper surface 111 including the opening of the recess 112. The opening is a region inside the opening edge indicated by reference numeral 113.

  The frame body portion 12 includes a ceramic material and has an annular shape. The exemplary frame 12 is substantially made of alumina. The space inside the frame body 12 corresponds to the cavity 14 of the ceramic structure 1. The frame body portion 12 surrounds the opening of the base body portion 11. In the present embodiment, surrounding the opening means that the opening is positioned inside the frame body portion 12 in plan perspective. In the base body portion 11 shown in FIG. 2, the position corresponding to the inner peripheral edge of the frame body portion 12 is indicated by a two-dot chain line. In FIG. 2, the opening is arranged in a region surrounded by a two-dot chain line.

  The lid portion 13 includes a ceramic material and has a flat plate shape. The exemplary lid portion 13 is substantially made of alumina. The lid part 13 covers the cavity part 14.

  The 1st example of the ceramic structure 1 has the structure where the base | substrate part 11, the frame part 12, and the cover part 13 are integrated by baking. The second example of the ceramic structure 1 has a structure in which the base portion 11 and the frame portion 12 are integrated by firing. In the second example of the ceramic structure 1, the lid portion 13 is joined to the frame portion 12. A third example of the ceramic structure 1 is a structure in which the frame body portion 12 and the lid body portion 13 are integrated by firing. In the third example of the ceramic structure 1, the lower end of the frame body portion 12 is joined to the base body portion 11.

  The cavity 14 and the recess 112 are preferably in a reduced pressure state including a vacuum state. Since the cavity 14 and the recess 112 are in a reduced pressure state, the loss of Joule heat generated in the current fuse element conductor pattern 2 is reduced. The cavity 14 and the recess 112 are preferably an inert gas atmosphere, a reducing gas atmosphere, or a mixed gas atmosphere of an inert gas and a reducing gas.

  The current fuse element conductor pattern 2 is provided so as to straddle the opening of the base portion 11 and is formed on the upper surface 111 of the base portion 11 by firing. The phrase “provided so as to straddle the opening” means that the current fuse element conductor pattern 2 is partially provided immediately above the opening and partially exposed to the recess 112.

  The current fuse element conductive pattern 2 includes a conductive material such as tungsten (W), molybdenum (Mo), or manganese (Mn). The current fuse element conductor pattern 2 is electrically connected to connection conductor patterns 5 and 6 provided on the upper surface 111 of the base portion 11. The connection conductor patterns 5 and 6 include, for example, a conductive material such as tungsten (W), molybdenum (Mo), or manganese (Mn), and are formed on the upper surface 111 of the base portion 11 by firing.

  When the pattern width of the current fuse element conductor pattern 2 is narrower than the pattern width of the connection conductor patterns 5 and 6, for example, when the current fuse element conductor pattern 2 and the connection conductor patterns 5 and 6 are made of the same material. However, the electrical resistance in the current fuse element conductor pattern 2 is larger than the electrical resistance in the connection conductor patterns 5 and 6. Therefore, when an overcurrent flows through the connection conductor patterns 5 and 6 and the current fuse element conductor pattern 2, the current fuse element conductor pattern 2 is blown. In FIG. 2, the pattern width of the current fuse element conductor pattern 2 refers to the width in the y-axis direction of the current fuse element conductor pattern 2. The pattern width of the connection conductor patterns 5 and 6 refers to the width in the y-axis direction of each of the connection conductor patterns 5 and 6.

  The terminals 3 and 4 are provided on the lower surface 114 of the base portion 11 and are electrically connected to the current fuse element conductor pattern 2. The terminals 3 and 4 include a conductive material such as tungsten (W), molybdenum (Mo), or manganese (Mn), and are formed on the lower surface 114 of the base portion 11 by firing. The fuse device in the present embodiment is a surface mount type device. The terminal 3 is electrically connected to the connection conductor pattern 5 by a castellation conductor 7. The terminal 4 is electrically connected to the connection conductor pattern 6 by a castellation conductor 8. The castellation conductors 7 and 8 are formed on the side surface 115 of the base portion 11 by firing.

  For example, a nickel plating film and a gold plating film are formed on the surfaces of the terminals 3 and 4 and the surfaces of the castellation conductors 7 and 8 so as to be mounted on the circuit board by, for example, solder bonding.

  Hereinafter, a method for manufacturing the current fuse device in the present embodiment will be described.

  As shown in FIG. 4, the method for manufacturing a current fuse device includes steps 401 to 403. Here, the manufacturing method of the current fuse device will be described with particular attention paid to the opening of the base portion 11 in the current fuse device.

  Step 401 includes embedding a burnable member 512 in the ceramic green sheet 51. A burnout member refers to a member that is removed by burning in the firing process of the ceramic green sheet. An exemplary burnable member includes a resin material. As shown in the upper part of FIG. 5, in step 401, a composite including the ceramic green sheet 51 and the burnable member 512 is obtained. In the upper part of FIG. 5, the burnout member 512 is shown in a transparent state, and the transparent part is shown by a dotted line.

  Step 402 includes applying the conductor paste 52 to the composite obtained by step 401. As shown in the middle part of FIG. 5, in step 402, an unfired structure including the composite and the conductive paste 52 is obtained. The conductive paste 52 is applied to the upper surface of the ceramic green sheet 51 and is also partially applied to the upper surface of the burnable member 512.

  Step 403 includes firing the green structure obtained by step 402. As shown in the lower part of FIG. 5, the structure having the current fuse element conductor pattern 2 provided so as to straddle the opening of the concave portion 112 in the base portion 11 is obtained in step 403.

  In the current fuse device of the present embodiment, the current fuse element conductor pattern 2 formed on the upper surface 111 of the base body portion 11 by firing is provided so as to straddle the opening of the recess 112. In the current fuse device, the loss of Joule heat at the fusing location of the conductor pattern 2 for the current fuse element is reduced. Therefore, the current fuse device according to the present embodiment is improved with respect to the temperature rise characteristic at the fusing portion of the current fuse element conductor pattern 2 in the overcurrent state, and is improved with respect to the fusing characteristic in the overcurrent state. The blowout portion of the current fuse element conductor pattern 2 refers to a portion of the current fuse element conductor pattern 2 that is designed to be blown when an overcurrent occurs.

  In the current fuse device according to the present embodiment, the recess 112 is in a reduced pressure state, so that the current fuse device according to the present embodiment is reduced with respect to the loss of Joule heat at the fusing portion of the current fuse element conductor pattern 2. Therefore, the current fuse device in the present embodiment is improved with respect to the fusing characteristics in an overcurrent state.

(Second Embodiment)
A current fuse device according to a second embodiment of the present invention will be described with reference to FIG. In the current fuse device according to the present embodiment, a configuration different from the current fuse device according to the first embodiment is that the base portion 11 has a plurality of heat transfer suppression portions 116. Other configurations are the same as those of the current fuse device according to the first embodiment.

  The plurality of heat transfer suppression portions 116 are provided so as to sandwich the recess 112 in the extending direction of the current fuse element conductor pattern 2. The extending direction of the current fuse element conductor pattern 2 is the direction in which the current flows in the current fuse element conductor pattern 2 or in the opposite direction. In FIG. That is. In FIG. 6, the plurality of heat transfer suppression portions 116 are indicated by dotted lines, and are provided so as to sandwich the recess 112 in the left-right direction.

  Each of the plurality of heat transfer suppressing portions 116 includes a plurality of groove portions 117. The plurality of groove portions 117 are provided so as to sandwich the current fuse element conductor pattern 2 in the width direction of the current fuse element conductor pattern 2. The width direction of the current fuse element conductor pattern 2 is a direction perpendicular to the direction of current flow in the current fuse element conductor pattern 2, and is a virtual y-axis direction in FIG. The plurality of grooves 117 are provided so as to sandwich the current fuse element conductor pattern 2 from both sides.

  As shown in FIG. 7, the present embodiment includes a structure in which the groove 117 is provided so as to be continuous with the recess 112. Each of the plurality of grooves 117 is formed so as to be continuous with the recess 112 in the extending direction of the current fuse element conductor pattern 2.

  In the current fuse device of the present embodiment, the base body portion 11 has a plurality of heat transfer suppression portions 116 provided so as to sandwich the recess 112 in the extending direction of the current fuse element conductor pattern 2. The current fuse device according to this embodiment is reduced in terms of conduction of Joule heat from the melted portion of the current fuse element conductor pattern 2 to the extending direction of the current fuse element conductor pattern 2. Therefore, the current fuse device according to the present embodiment is improved with respect to the temperature rise characteristic at the fusing portion of the current fuse element conductor pattern 2 in the overcurrent state, and is improved with respect to the fusing characteristic in the overcurrent state.

  In the current fuse device of the present embodiment, each of the plurality of heat transfer suppression portions 116 includes a plurality of groove portions 17 provided so as to sandwich the current fuse element conductor pattern 2 in the width direction of the current fuse element conductor pattern 2. By including the current fuse device in this embodiment, the conduction of Joule heat from the current fuse element conductor pattern 2 to the width direction of the current fuse element conductor pattern 2 is reduced. Therefore, the current fuse device in the present embodiment is improved with respect to the fusing characteristics in an overcurrent state.

(Third embodiment)
A circuit board according to a third 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 current fuse portion 84 embedded in the insulating base 83. In FIG. 8, a part of the insulating base 83 is omitted for the purpose of showing the current fuse portion 84. The current fuse portion 84 includes a ceramic layer 85 and a current fuse element conductor pattern 86. The ceramic layer 85 has an upper surface including the opening of the recess 851. The opening of the recess 851 is an inner region of the opening edge indicated by reference numeral 852. The current fuse element conductor pattern 86 is formed on the upper surface of the ceramic layer 85 by firing and is provided so as to straddle the opening.

  In the circuit board according to the present embodiment, the current fuse element conductor pattern 86 formed on the upper surface of the ceramic layer 85 by firing is provided so as to straddle the opening of the recess 851, whereby the circuit board according to the present embodiment. Is reduced with respect to the loss of Joule heat at the melting point of the conductor pattern 86 for the current fuse element. Therefore, the circuit board according to the present embodiment is improved with respect to the temperature rise characteristic at the fusing position of the current fuse element conductor pattern 86 in the overcurrent state, and is improved with respect to the fusing characteristic in the overcurrent state.

  In the circuit board of the present embodiment, it is also possible to apply a structure related to the plurality of heat transfer suppression units 116 in the current fuse device of the second embodiment.

  In the circuit board of this embodiment, a plurality of current fuse portions can be embedded.

DESCRIPTION OF SYMBOLS 1 Ceramic structure 11 Base part 12 Frame part 13 Cover part 111 Upper surface 112 of base part 11 Recessed part 2 Conductive pattern for current fuse elements

Claims (2)

A base part having an upper surface including an opening part of a concave part, a frame part provided on the base part and surrounding the opening part, and a lid part provided on the frame part A ceramic structure
A current fuse device which is formed on the upper surface of the base portion by firing and includes a conductor pattern for a current fuse element provided so as to straddle the opening , and the concave portion is in a decompressed state . A current fuse portion, and the current fuse portion is formed on the upper surface of the ceramic layer by firing and straddling the opening portion, the ceramic layer including an opening portion of a recess circuit board viewed including the conductor pattern current fuse element, characterized in that it has a plurality of grooves provided so as to sandwich the concave portion from both sides in the extending direction of the conductor pattern for said current fuse element .

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