JP2011222440A - Current fuse and package of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current fuse and a current fuse package which can contribute to improve operation characteristics.SOLUTION: The current fuse includes a circuit board, a pair of electrodes mounted on the circuit board, and a thermal fuse element mounted on the circuit board whose one end is to be connected to one of the pair of electrodes and the other end is to be connected to the other of the pair of electrodes. The circuit board is provided with a pair of protrusion portions whose upper surface is protruded upward, and the thermal fuse element is arranged to block in between the pair of protrusion portions.

Description

  The present invention relates to a current fuse and a current fuse package.

  In recent years, development for improving the operating characteristics of current fuses has been advanced (see, for example, Patent Document 1). The current fuse needs to control the melting temperature of the thermal fuse element provided on the substrate.

JP 2004-14224 A

  In the development of current fuses, there is a need for a technique for bringing the temperature at which the thermal fuse element melts close to a desired temperature.

  The present invention has been made in view of the above, and an object of the present invention is to provide a current fuse and a current fuse package that can contribute to an improvement in operating characteristics.

  A current fuse according to an embodiment of the present invention includes a substrate, a pair of electrodes provided on the substrate, and provided on the substrate, one end connected to one of the pair of electrodes and the other end A thermal fuse element connected to the other of the pair of electrodes, wherein the substrate is provided with a pair of protrusions whose upper surfaces protrude upward, and between the pair of protrusions The thermal fuse element is disposed so as to close the gap.

  A current fuse according to an embodiment of the present invention includes a substrate, a pair of electrodes provided on the substrate, and provided on the substrate, one end connected to one of the pair of electrodes and the other end A thermal fuse element connected to the other of the pair of electrodes, wherein the substrate has a recess provided between the pair of electrodes, and the recess further includes the pair of electrodes. A groove is provided from one of the electrodes to the other, and the thermal fuse element is disposed so as to close the groove.

  A current fuse package according to an embodiment of the present invention includes a substrate, a pair of electrodes provided on the substrate, and provided on the substrate, one end of which is connected to one of the pair of electrodes and the other end A mounting surface for mounting a thermal fuse element connected to the other of the pair of electrodes, and the substrate is provided with a pair of protrusions whose upper surfaces protrude upward The mounting surface is located between the pair of convex portions.

  A current fuse package according to an embodiment of the present invention includes a substrate, a pair of electrodes provided on the substrate, and provided on the substrate, one end of which is connected to one of the pair of electrodes and the other end A mounting surface for mounting a thermal fuse element connected to the other of the pair of electrodes, and the substrate is provided with a recess between the pair of electrodes, and The recess is provided with a groove from one to the other of the pair of electrodes, and the mounting surface is located in the groove.

  ADVANTAGE OF THE INVENTION According to this invention, the current fuse which can contribute to the improvement of an operating characteristic, and a current fuse package can be provided.

It is a perspective view which shows the external appearance of the current fuse which concerns on this embodiment. It is a perspective view which shows the state which removed the flux from the current fuse of FIG. It is a perspective view which shows the state which removed the flux and the thermal fuse element from the current fuse of FIG. FIG. 4 is a cross-sectional view of the current fuse taken along X-X ′ in FIG. 3. FIG. 4 is a cross-sectional view of the current fuse taken along Y-Y ′ in FIG. 3. It is a perspective view which shows the general appearance of a heating resistor. It is a perspective view which shows the external appearance of the current fuse which concerns on one modification. FIG. 8 is a cross-sectional view of the current fuse taken along Z-Z ′ in FIG. 7.

  Embodiments of a current fuse according to the present invention will be described below with reference to the accompanying drawings. In addition, this invention shall not be limited to the following embodiment.

<Configuration of current fuse>
The current fuse of this embodiment is used as a circuit protection element, and is incorporated in a specific circuit together with an abnormality detector. When an abnormality occurs in the circuit, an overcurrent flows through the current fuse, and the temperature fuse element of the current fuse is blown due to the heat, thereby urgently stopping the operation of the circuit.

  A resistance temperature fuse 1 according to the present embodiment is provided on a substrate 2, a pair of electrodes 3 provided on the substrate 2, and one end of one end connected to one of the pair of electrodes 3. Includes a thermal fuse element 4 connected to the other of the pair of electrodes 3.

  In addition, the current fuse package according to the present embodiment is obtained by removing the thermal fuse element 4 from the resistance thermal fuse 1. The substrate 2 is provided with a mounting surface R on which the thermal fuse element 4 is mounted. The mounting surface R is provided between a pair of convex portions 2A from which the upper surface of the substrate 2 protrudes upward.

  The substrate 2 has a pair of convex portions 2A whose upper surfaces protrude upward. The board | substrate 2 is set to the rectangular shape when planarly viewed. The substrate 2 is an insulating substrate and is made of, for example, a ceramic material such as alumina, mullite, or aluminum nitride, or a glass ceramic material. Or it consists of a composite material which mixed several materials among these materials. In addition, the thickness from the upper surface of the convex part 2A of the substrate 2 to the lower surface of the substrate 2 is set to 0.1 mm or more and 3 mm or less, for example. Moreover, the thickness of only the convex part 2A of the board | substrate 2 is set to 0.05 mm or more and 1 mm or less, for example. Furthermore, the thermal conductivity of the board | substrate 2 is set to 14 W / m * K or more and 200 W / m * K or less, for example.

  Each of the pair of convex portions 2A is set in a rectangular shape. And a pair of convex part 2A is arranged along with the board | substrate 2, and is arrange | positioned so that it may become fixed between both. Here, when the distance between the two is constant, the length from one inner wall surface of the pair of convex portions 2A to the other inner wall surface of the pair of convex portions 2A is, for example, 2.0 mm when viewed in plan. The state is set to 3.0 mm or less and the error is 0.05 mm or less.

  Moreover, the depth of the area | region pinched | interposed by a pair of convex part 2A is set to the fixed depth. Here, the constant depth is set, for example, from a height position of the upper surface of the convex portion 2A to a height position of a region sandwiched between the pair of convex portions 2A, for example, 0.1 mm or more and 1.0 mm or less. And the error is 0.05 mm or less.

  A pair of electrode layers 3 that are electrically connected to the thermal fuse element when the thermal fuse element 4 is mounted are formed on the upper surface of the substrate 2. Further, the pair of electrode layers 3 is not formed in a region protruding above the upper surface of the substrate 2.

  A part of each of the pair of electrode layers 3 is formed from the upper surface of the substrate 2 to the lower surface of the substrate 2 via the side surface of the substrate 2. In the present embodiment, the electrode layer 3 is formed so that the pair of electrode layers 3 are electrically opened when the thermal fuse element 4 is melted.

  The electrode layer 3 is, for example, a metal material such as tungsten, molybdenum, nickel, copper, silver, gold or aluminum, or an alloy thereof, or a composite material obtained by mixing a plurality of these materials, or a material thereof. It consists of a composite layer.

  As shown in FIG. 4, a part 3 </ b> A of the electrode layer 3 extends to a region where the thermal fuse element 4 is provided. The width of the part 3A of the electrode layer 3 corresponds to the length from one inner wall surface of the pair of convex portions 2A to the other inner wall surface of the pair of convex portions 2A. The length of the width is set to, for example, 0.5 mm or more and 1.0 mm or less.

  The width of the part 3A of the electrode layer 3 is set to be smaller than the width of the electrode layer 3 provided other than between the pair of convex portions 2A. In the current fuse 1, a current flows between the pair of electrode layers 3 through the temperature fuse element 4. When a current flows between the pair of electrode layers 3, when the current flows in a portion where the width of the electrode layer 3 is small, the portion has a large electric resistance value, so a part of the current is converted into heat and generates heat. . As a result, the amount of heat generated can be increased between the pair of convex portions 2A, and the thermal fuse element 4 can be easily melted.

  Further, in the region where the thermal fuse element 4 is provided, a heating resistor 5 is provided, one end of which is connected to one of the pair of electrodes 3 and the other end is spaced from the other of the pair of electrodes 3. Yes. FIG. 6 is a schematic perspective view of the heating resistor 5.

  The temperature fuse element 4 is transmitted to the temperature fuse element 4 to melt the temperature fuse element 4. The heating resistor 5 is an area that overlaps the thermal fuse element 4 in a plan view, and is provided between the thermal fuse element 4 and the upper surface of the substrate 2.

  The heating resistor 5 is provided with one end connected to one of the pair of electrode layers 3 and the other end spaced from the pair of electrode layers 3. The heating resistor 5 has a resistance value for securing a required heat generation amount. As an example of the resistance value securing method, the pattern shape is bent many times between the pair of convex portions 2A. Is formed. The width of the heating resistor 5 is set to be smaller than the width of the part 3A of the electrode layer 3 formed between the pair of convex portions 2A. By making the width of the heating resistor 5 smaller than the width of the part 3A of the electrode layer 3, the electrical resistance of the heating resistor 5 is increased, and the control of the Joule heat generated in the heating resistor 5 portion can be easily performed. can do.

  The heating resistor 5 is energized to the heating resistor 5 via the electrode layer 3 by detecting an abnormality of the circuit by an abnormality detector incorporated in the circuit together with the current fuse. And since the electrical resistance of the heating resistor 5 is large, the temperature of the heating resistor 5 rises. Further, the temperature is transmitted to the thermal fuse element 4 and blown when the thermal fuse element 4 reaches a predetermined temperature or higher. The heating resistor 5 is made of a material such as tungsten or platinum, for example.

  The thermal fuse element 4 is disposed so as to block between the pair of convex portions 2A whose upper surface protrudes upward. The thermal fuse element 4 is blown when the temperature exceeds a specific temperature. The thermal fuse element 4 is made of, for example, a low melting point conductive material such as indium, bismuth or tin, or a mixed material thereof. Further, the melting point at which the thermal fuse element 4 is melted is set to 80 ° C. or higher and 180 ° C. or lower, for example.

  Both ends of the thermal fuse element 4 are electrically connected to the pair of electrode layers 3. A part of the thermal fuse element 4 is electrically connected to the heating resistor 5. The thermal fuse element 4 is formed in a rectangular shape in plan view. The thermal fuse element 4 is provided so as not to protrude from between the pair of convex portions 2A. As a result, the thickness of the thermal fuse element 4 can be adjusted to a predetermined thickness. In addition, the thickness of the thermal fuse element 4 is set to 0.1 mm or more and 1.0 mm or less, for example.

  Further, in the place where the thermal fuse element 4 is disposed, the length between one inner wall surface of the pair of convex portions 2A and the other inner wall surface of the pair of convex portions 2A is adjusted to be constant in plan view. Has been. The temperature fuse element 4 is set to be a rectangular parallelepiped. As a result, the width of the thermal fuse element 4 when viewed in plan can be adjusted to a predetermined width. The width of the thermal fuse element 4 is set to 0.5 mm or more and 1.0 mm or less, for example.

  A current flows between the pair of electrode layers 3 through the thermal fuse element 4, but by adjusting the shape of the thermal fuse element 4 to be a rectangular parallelepiped, variation in the current flowing through the thermal fuse element 4 is suppressed. Can do. Then, by adjusting the shape of the thermal fuse element 4, the heat capacity of the thermal fuse element 4 can be made close to a constant value between one end and the other end of the thermal fuse element 4.

  The heat capacity per unit area of the thermal fuse element 4 can be made close to a constant value, and variations in the heat capacity per unit area can be reduced. As a result, a current flows through the thermal fuse element 4, and heat generated based on the current can be uniformly transmitted to the thermal fuse element 4.

  If the thermal capacities per unit area of the thermal fuse element 4 are greatly different in the thermal fuse element 4, the temperature rises at a location where the thermal capacity is small, so that heat tends to concentrate on a specific location on the thermal fuse element 4. Become. In the thermal fuse element 4, the thermal fuse element 4 is melted out at a location where heat is concentrated, and the thermal fuse element 4 is melted around the location. For this reason, even if the external circuit incorporating the thermal fuse 1 is operating normally, the thermal fuse element 4 may be melted and the external circuit may malfunction.

  Therefore, the shape of the thermal fuse element 4 is made rectangular so that current concentration does not easily occur in the thermal fuse element 4. And the heat capacity per unit area of the thermal fuse element 4 can be made constant, and it can suppress that heat concentrates on the specific location of the thermal fuse element 4. FIG.

  The thermal fuse element 4 is covered with a flux 6. The flux 6 is a material having excellent thermal conductivity, and is made of, for example, a material obtained by dissolving pine resin in turpentine oil to form a paste, or a material such as zinc chloride. The flux 6 makes it easy to transmit the temperature of the heating resistor 5 to the thermal fuse element 4. Then, the temperature difference between the temperature of the heating resistor 5 and the temperature fuse element 4 can be reduced.

  If the thickness of the thermal fuse element is not formed to be substantially constant, a portion having a small thickness is likely to be melted. Moreover, if the width | variety of a thermal fuse element is not formed substantially constant, the location where a width | variety is small will become easy to melt | fuse. Therefore, the shape of the thermal fuse element 4 provided in the current fuse 1 is set to a rectangular parallelepiped so that the thickness and width are made substantially constant. In the present embodiment, a desired shape is set between the pair of convex portions 2A, and the thermal fuse element 4 is filled and solidified between the pair of convex portions 2A so that the rectangular thermal fuse element 4 is formed. Can be formed. As a result, by setting the heat transmitted from the heating resistor 5 to the thermal fuse element 4 to be transmitted to the thermal fuse element 4 substantially uniformly, the difference in the heat capacity per unit area of the thermal fuse element 4 is reduced, and the temperature Concentration of heat on the fuse element 4 can be suppressed.

  As described above, according to the present embodiment, the current fuse 1 incorporated in a device suppresses the concentration of heat at a specific location of the thermal fuse element 4, thereby improving the fusing characteristics of the thermal fuse element 4. can do. As a result, the thermal fuse element 4 can be blown at a desired temperature, and the operating characteristics of the current fuse 1 can be improved.

  In this embodiment, since the thermal fuse element 4 is provided between the pair of convex portions 2A, the material melted by the thermal fuse element 4 leaks onto the electrode layer 3 from between the one or more convex portions 2A. And can be adjusted so that it solidifies again on the electrode layer 3. Here, the leaked thermal fuse element 4 on the electrode layer 3 is solidified in a region outside the pair of convex portions 2A as compared with a region in the pair of convex portions 2A where the heating resistor 5 exists. However, it is easier to solidify because of its low temperature. As a result, the melted temperature fuse element 4 can be prevented from adhering to the external device, and the possibility of malfunction of the external device can be reduced.

  In addition, this invention is not limited to the above-mentioned form, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention. Hereinafter, modifications of the present embodiment will be described. Note that, among the current fuses according to the modified example of the present embodiment, portions similar to those of the current fuse according to the present embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

<Modification>
FIG. 7 is a schematic perspective view of a current fuse according to a modification. FIG. 7 shows a state where the flux is removed from the current fuse. FIG. 8 is a cross-sectional view of the current fuse taken along the line ZZ ′ of FIG.

  In the above-described embodiment, the thermal fuse element 4 is disposed so as to block between the pair of convex portions 2 </ b> A provided on the substrate 2, but is not limited thereto.

  In the current fuse 1 according to a modification, the substrate 2 is provided with a recess 2B between a pair of electrodes 3, and the recess 2B is provided with a groove 2BX from one of the pair of electrodes 3 to the other. Yes. And the thermal fuse element 4 is arrange | positioned so that the groove part 2BX may be plugged up.

  The recess 2 </ b> B is provided from one inner wall surface of the pair of electrodes 3 to the other inner wall surface of the pair of electrodes 3.

  The recess 2B is set in a rectangular shape except for the portion of the groove 2BX. When viewed in plan, the length from one inner wall surface of the pair of electrode layers 3 to the other inner wall surface of the pair of electrode layers 3 is set to, for example, 2.0 mm or more and 3.0 mm or less. The state where the error is 0.05 mm or less.

  Further, the depth of the recess 2B is set to a constant depth except for the location of the groove 2BX. Here, the constant depth is set such that the height from the top surface of the electrode layer 3 to the bottom surface of the recess 2B is set to, for example, 0.1 mm or more and 1.0 mm or less. It means a state where the error is 0.05 mm or less.

  The groove 2BX is formed in a part of the bottom surface of the recess 2B. The groove 2BX is continuously formed from one inner wall surface of the pair of electrode layers 3 to the other inner wall surface of the pair of electrode layers 3 in plan view. The depth of the groove 2BX is the length from the height position of the region where the groove 2BX of the recess 2B is not provided to the height position of the bottom surface of the groove 2BX, for example, 0.1 mm or more and 1.0 mm. It is set as follows.

  In the thermal fuse of this modification, the thickness of the entire current fuse is reduced by setting the region in which the thermal fuse element 4 is provided to be lower than the height position of the region in which the electrode layer 3 is formed. Can contribute to downsizing of the entire apparatus.

<Current fuse manufacturing method>
Here, a method of manufacturing the current fuse 1 shown in FIG. 1 will be described.

  First, the substrate 2 is prepared. When the material constituting the substrate 2 is made of, for example, an aluminum oxide sintered body, an organic binder, a plasticizer, a solvent, and the like are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, magnesium oxide and calcium oxide. The resulting mixture is obtained.

  And the mixture is filled in the mold of the substrate 2, and the green body of the substrate 2 is taken out from the mold. In addition, the board | substrate 2 can be shape | molded and produced by making the formwork of the board | substrate 2 into the shape of the board | substrate 2 which has a pair of convex part 2A previously.

  Moreover, a high melting point metal powder such as nickel or molybdenum is prepared, and an organic binder, a plasticizer, a solvent, or the like is added to and mixed with the powder to obtain a high melting point metal paste. Then, a refractory metal paste is applied to the upper surface of the unsintered substrate 2 to pattern the pair of electrode layers 3. Furthermore, the electrode layer 3 can be patterned by applying a metal paste to the side surface of the substrate 2 and the lower surface of the substrate 2.

  Moreover, a high resistance metal powder such as tungsten or platinum is prepared, and an organic binder, a plasticizer, a solvent, or the like is added to and mixed with the powder to obtain a high resistance metal paste. A high resistance metal paste is applied to a predetermined portion between the pair of convex portions 2A of the substrate 2 to pattern the heating resistor 5.

  Next, the substrate 2 on which the electrode layer 3 and the heating resistor 5 are patterned is baked at a temperature of about 1600 degrees. Further, the thermal fuse element 4 made of solder paste is filled in the area between the pair of convex portions 2A on the upper surface of the substrate 2 after firing, for example, using a screen printing method. Here, the solder paste is composed of a low melting point conductive material. The thermal fuse element 4 may be formed by embedding a preform-formed thin film in the pair of convex portions 2A.

  Then, the thermal fuse element 4 and the electrode layer 3 are electrically connected. Further, a flux 6 is formed on the substrate 2 so as to cover the thermal fuse element 4. In this way, the current fuse 1 can be manufactured. Note that a current fuse according to one modification can also be manufactured by using this manufacturing method.

1 Current fuse 2 Substrate 2A Convex 3 Electrode 4 Thermal fuse element 5 Heating resistor 6 Flux

Claims (7)

A substrate,
A pair of electrodes provided on the substrate;
A thermal fuse element provided on the substrate and having one end connected to one of the pair of electrodes and the other end connected to the other of the pair of electrodes;
The current fuse is characterized in that the substrate is provided with a pair of protrusions whose upper surfaces protrude upward, and the thermal fuse element is disposed so as to close the space between the pair of protrusions. A substrate,
A pair of electrodes provided on the substrate;
A thermal fuse element provided on the substrate and having one end connected to one of the pair of electrodes and the other end connected to the other of the pair of electrodes;
The substrate is provided with a recess between the pair of electrodes, and further, the recess is provided with a groove from one to the other of the pair of electrodes,
The current fuse, wherein the thermal fuse element is disposed so as to close the groove. The current fuse according to claim 2,
The pair of electrodes extends to the inside of the groove portion, and the pair of electrodes are provided with a gap in the groove portion. A current fuse according to any one of claims 1 to 3,
The region where the thermal fuse element is provided further comprises a heating resistor having one end connected to one of the pair of electrodes and the other end spaced from the other of the pair of electrodes. Characteristic current fuse. A current fuse according to any one of claims 1 to 4,
The current fuse, wherein the thermal fuse element is covered with a flux. A substrate,
A pair of electrodes provided on the substrate;
A current fuse package provided on the substrate, the mounting surface mounting a thermal fuse element having one end connected to one of the pair of electrodes and the other end connected to the other of the pair of electrodes. Because
The substrate is provided with a pair of convex portions whose upper surfaces protrude upward, and the mounting surface is located between the pair of convex portions. A substrate,
A pair of electrodes provided on the substrate;
A current fuse package provided on the substrate, the mounting surface mounting a thermal fuse element having one end connected to one of the pair of electrodes and the other end connected to the other of the pair of electrodes. Because
The substrate is provided with a recess between the pair of electrodes, and further, the recess is provided with a groove from one to the other of the pair of electrodes,
The current fuse package, wherein the mounting surface is located in the groove.

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