JP6040581B2 - Fuse and manufacturing method thereof - Google Patents

Description

The present invention relates to a fuse for cutting a current path when an overcurrent is applied, and a method for manufacturing the fuse.

  Fuses are used to protect electronic circuits and electronic components from overcurrent. When an overcurrent is applied to the electronic circuit in which the fuse is placed, the fuse generates heat, melts, and breaks the current path. Thereby, the electronic circuit and the electronic component are protected from heat generation or damage due to overcurrent. Conventional fuses are disclosed in Patent Documents 1 and 2, for example.

  The fuse described in Patent Document 1 includes a substantially flat substrate, a first electrode, a second electrode, and a fusible metal. The first electrode is formed at one end of the substrate, and the second electrode is formed at the other end of the substrate. The fusible metal is formed on the main surface of the substrate and is joined to the first and second electrodes. When an overcurrent is applied between the first and second electrodes, the fusible metal generates heat and melts. As a result, the fuse described in Patent Document 1 cuts the current path.

  The fuse described in Patent Document 2 includes a substantially flat plate-like first electrode, a substantially flat plate-like second electrode, and a substantially rectangular parallelepiped fusible metal. The end portion of the first electrode and the end portion of the second electrode face each other. The fusible metal is located in a portion where the first electrode and the second electrode are opposed to each other. The fuse described in Patent Document 2 also cuts the current path by the same mechanism as that of the fuse described in Patent Document 1.

JP 2007-165086 A JP-A-64-17349

  In the case of the fuse described in Patent Document 1, the fusible metal melted by the overcurrent is scattered to the outside, and there is a risk of causing problems such as a short circuit in surrounding electronic devices. Moreover, since the meltable fusible metal may remain between the first and second electrodes, there is a possibility that the first and second electrodes are short-circuited again. Furthermore, when the fuse includes a protective layer, the meltable fusible metal does not scatter to the outside and tends to stay between the first and second electrodes, so that the first and second electrodes may be short-circuited again. Get higher.

  Even in the case of the fuse described in Patent Document 2, the fusible metal melted by the overcurrent is scattered to the outside, and there is a risk that a short circuit or the like may occur in surrounding electronic devices. In addition, when the first and second electrodes sandwich the fusible metal from above and below, the current path is reliably cut, but when the first and second electrodes sandwich the fusible metal from the lateral direction, There is a possibility that the molten metal stays between the first electrode and the second electrode, and the retained fusible metal short-circuits again between the first and second electrodes.

An object of the present invention is to provide a highly reliable fuse and a method of manufacturing the same regardless of the mounting mode.

The fuse according to the present invention is characterized by the following configuration. The fuse includes a substrate, a first electrode, a second electrode, a support portion, and a fusible metal portion. The first electrode is formed on the main surface of the substrate. The second electrode is opposed to the first electrode. The support portion fixes the position of the second electrode with respect to the first electrode. The fusible metal part is located between the first electrode and the second electrode. The support portion surrounds the fusible metal portion when viewed from a direction perpendicular to the main surface of the substrate. When the fusible metal part melts in all parts between the first electrode and the second electrode and between the support part and the fusible metal part , the fusible metal part spreads space Ru is formed. The first electrode and the second electrode are larger than the fusible metal portion when viewed from the direction perpendicular to the main surface of the substrate.

  In this configuration, the molten fusible metal spreads into the surrounding space and resolidifies. Thereby, the meltable fusible metal part does not short-circuit between the first and second electrodes again. Therefore, it is possible to realize a fuse that reliably cuts the current path regardless of the mounting mode.

  The fuse according to the present invention may be configured as follows. The substrate includes a first substrate and a second substrate. The first electrode is formed on the main surface of the first substrate. The second electrode is formed on the main surface of the second substrate.

  In the fuse according to the present invention, the first substrate, the second substrate, and the support portion may form a casing, and the fusible metal portion may be disposed in the casing. In this configuration, the molten fusible metal remains in the housing. Therefore, it is possible to reliably prevent the molten fusible metal portion from being scattered outside.

  The fuse according to the present invention may be configured as follows. The first substrate, the first electrode, a part of the fusible metal part, and a part of the support part form a first structure. The second substrate, the second electrode, the other part of the fusible metal part, and the other part of the support part form a second structure. The first structure body and the second structure body are the same. In this configuration, the fuse can be realized with a simple structure.

The fuse according to the present invention may be configured as follows. Fusible metal portion comprising a plurality of fusible metal, the plurality of fusible metal is formed in layers in a direction perpendicular to the main surface of the board. The fusible metal in contact with the first and second electrodes has a lower melting point than other fusible metals.

  The fuse according to the present invention may include a heating part for heating the fusible metal part. In this configuration, by causing the heater electrode to generate heat, the fusible metal part can be melted at an arbitrary timing to cut the current path.

The fuse manufacturing method according to the present invention is characterized by the following configuration. In the first step, a first low melting point fusible metal is formed on the first substrate on which the first electrode is formed. In the second step, a second low melting point fusible metal is formed on the second substrate on which the second electrode is formed. In the third step, the first electrode and the second electrode are opposed to each other, and a support portion for fixing the position of the second electrode with respect to the first electrode is provided, and the first electrode and the second electrode are provided. A high melting point fusible metal is provided between them. In the third step, the support portion is provided so that the support portion surrounds the refractory metal as viewed from the direction perpendicular to the main surface of the first substrate. When the high melting point fusible metal is melted in all the portions between the first electrode and the second electrode and between the support portion and the high melting point fusible metal, the high melting point fusible metal is Form a space to spread. The high melting point fusible metal is provided so that the first electrode and the second electrode are larger than the high melting point fusible metal when viewed from the direction perpendicular to the main surface of the first substrate.

  In this configuration, since a necessary structure is formed on the substrate, productivity can be improved.

The method for manufacturing a fuse according to the present invention may be configured as follows. Refractory fusible metal is formed first and second high melting fusible metals or al. The third step includes the following steps. The first high melting point fusible metal is fixed to the surface of the first low melting point fusible metal. The second high melting point fusible metal is fixed to the surface of the second low melting point fusible metal. The first refractory metal and the second refractory metal are brought into contact with each other.

  In this configuration, since the fuse can be manufactured by combining the structures formed on the substrate, the productivity can be further improved.

  Regardless of the embodiment, the fuse that reliably cuts the current path can be realized with a simple configuration.

1 is an external perspective view of a fuse according to a first embodiment. It is sectional drawing of the fuse which concerns on 1st Embodiment. It is A-A 'arrow sectional drawing which shows the manufacturing process of the fuse which concerns on 1st Embodiment. It is A-A 'arrow sectional drawing of the fuse which concerns on 2nd Embodiment. It is A-A 'arrow sectional drawing which shows the manufacturing process of the fuse which concerns on 2nd Embodiment. It is A-A 'arrow sectional drawing which shows 1 process of the manufacturing method of the fuse which concerns on 3rd Embodiment.

  A fuse according to a first embodiment of the present invention will be described. In the following figures, hatching notation is adopted for the conductive members. In the following description, the upper side of FIG. 2A is referred to as the top surface side, and the lower side of the drawing is referred to as the bottom surface side.

  FIG. 1 is an external perspective view of the fuse according to the first embodiment. FIG. 2 is a cross-sectional view of the fuse according to the first embodiment. FIG. 2A is a cross-sectional view taken along the line A-A ′. FIG. 2B is a cross-sectional view taken along arrow B-B ′.

  The fuse 1 according to the first embodiment includes substrates 10A and 10B, electrodes 14A and 14B, fusible metals 15A, 15B, and 17, support portions 16, via electrodes 13A and 13B, and external connection electrodes 12A and 12B. ing. The fusible metals 15A, 15B, and 17 constitute the fusible metal part according to the first embodiment.

  The substrate 10A is a rectangular flat plate-like insulating substrate. The substrate 10A is made of, for example, an FR-4 substrate (glass cloth base epoxy resin substrate), a ceramic substrate, a glass substrate, and other resin substrates. The substrate 10B has the same shape and material as the substrate 10A. The substrate 10A and the substrate 10B are arranged so that their main surfaces face each other.

  The electrode 14A is formed on the top surface of the substrate 10A. The electrode 14A has a rectangular flat plate-like outer shape. The area of the flat plate surface of the electrode 14A is smaller than the area of the flat plate surface of the substrates 10A and 10B. The electrode 14B is formed on the bottom surface of the substrate 10B. The electrode 14B has the same shape and material as the electrode 14A.

  The support portion 16 is located between the substrates 10A and 10B, and fixes the position of the substrate 10B with respect to the substrate 10A. Thereby, the flat surface of electrode 14A, 14B opposes each other. The support portion 16 has a substantially rectangular tube-like outer shape, and the end surface of the support portion 16 is in contact with the outer periphery of the substrates 10A and 10B. Thereby, the support part 16 forms the housing | casing with board | substrate 10A, 10B. The support portion 16 is made of, for example, a thermosetting resin such as an epoxy resin.

  The fusible metal 15A is formed on the top surface of the electrode 14A. The fusible metal 15A has a rectangular flat plate-like outer shape. The area of the flat plate surface of the fusible metal 15A is smaller than the area of the flat plate surface of the electrodes 14A and 14B. The fusible metal 15A is, for example, a solder paste such as Sn-3.5Ag-0.5Cu. The fusible metal 15A is used for mounting the fusible metal 17 on the electrode 14A.

  The fusible metal 15B is formed on the bottom surface of the electrode 14B. The fusible metal 15B is used for mounting the fusible metal 17 on the electrode 14B. The fusible metal 15B has the same shape and material as the fusible metal 15A.

  The fusible metal 17 is formed between the electrodes 14A and 14B via the fusible metals 15A and 15B. That is, the fusible metals 15A, 15B, and 17 are formed in layers in a direction perpendicular to the main surface of the electrode 14A, and are positioned between the electrodes 14A and 14B. The fusible metal 17 has a substantially rectangular parallelepiped outer shape. The bottom surface of the fusible metal 17 has the same shape as the top surface of the fusible metal 15A, and the top surface of the fusible metal 17 has the same shape as the bottom surface of the fusible metal 15B. The fusible metal 17 is made of, for example, a solder alloy such as a Sn-10Sb alloy.

  As described above, the area of the top and bottom surfaces of the fusible metal 17 and the area of the flat plate surfaces of the fusible metals 15A and 15B are smaller than the area of the flat plate surfaces of the electrodes 14A and 14B. Thereby, a space for spreading the meltable fusible metals 15A, 15B, 17 is formed between the electrodes 14A, 14B.

  The fusible metal 17 may be composed of a plurality of parts.

  The via electrode 13A penetrates the substrate 10A and is connected to the electrode 14A. The via electrode 13B penetrates the substrate 10B and is connected to the electrode 14B.

  The external connection electrode 12 </ b> A covers one end of a housing composed of the substrates 10 </ b> A and 10 </ b> B and the support portion 16. The external connection electrode 12B covers the other end of the casing. The external connection electrode 12A is connected to the electrode 14A through the via electrode 13A. The external connection electrode 12B is connected to the electrode 14B through the via electrode 13B.

  The fuse 1 has a current path connected in the order of the external connection electrode 12A, the via electrode 13A, the electrode 14A, the fusible metals 15A, 17, 15B, the electrode 14B, the via electrode 13B, and the external connection electrode 12B.

  When overcurrent flows through the fuse 1, the fusible metals 15A, 15B, and 17 generate heat and melt. The meltable fusible metals 15A, 15B, 17 are spread in the surrounding space along the electrodes 14A, 14B, and are divided in a direction perpendicular to the main surface of the substrate 10A by surface tension.

  When the fuse 1 is arranged with the substrate 10A facing downward, the meltable fusible metals 15A, 15B, and 17 are mainly spread and wetted in the space around the electrode 14A, and re-solidify. When the fuse 1 is arranged with the substrate 10A substantially vertical, the meltable fusible metals 15A, 15B, and 17 are mainly spread in the lower space and re-solidified.

  Thereby, the meltable fusible metals 15A, 15B, and 17 do not short-circuit again between the electrodes 14A and 14B. Therefore, the fuse 1 can reliably cut the current path regardless of the mounting mode.

  In addition, the fusible metals 14A, 14B, and 17 are disposed in a housing formed of the substrates 10A and 10B and the support portion 16. Therefore, the meltable fusible metals 14A, 14B, and 17 stay in the casing and do not scatter outside.

  Further, when the fuse 1 is divided by a surface having the same distance between the main surface of the substrate 10A and the main surface of the substrate 10B, the structure of the surface on the substrate 10A side and the structure of the surface on the substrate 10B side are the same. Therefore, the fuse 1 is realized with a simple structure.

In addition, the shape of each part which comprises the fuse 1 is not limited above. For example,
The support unit 16 may include a plurality of columns, and the position of the substrate 10B with respect to the substrate 10A may be fixed by the columns. For example, without providing the substrate 10B, the support portion 16 may directly fix the position of the electrode 14B with respect to the electrode 14A.

  Next, an example of a method for manufacturing the fuse 1 will be described. FIG. 3 is a cross-sectional view taken along the line A-A ′ showing the manufacturing process of the fuse 1 step by step.

  In the step shown in FIG. 3A, a predetermined via electrode 13A is formed inside the substrate 10A, and a predetermined electrode pattern is formed by thermocompression bonding a metal foil to a predetermined position of the substrate 10A. Thereby, the electrode 14A is formed on the substrate 10A.

  In the step shown in FIG. 3A, a predetermined via electrode 13A is formed inside the substrate 10A, and a predetermined electrode pattern is formed by thermocompression bonding a metal foil to a predetermined position of the substrate 10A. Thereby, the electrode 14A is formed on the substrate 10A.

  In the step shown in FIG. 3B, a solder paste is printed on the electrode 14A using a metal mask or the like. For example, Sn-3.5Ag-0.5Cu may be used as the solder paste.

  In the step shown in FIG. 3C, a solder alloy formed in a predetermined shape is placed on the solder paste. For example, Sn-10Sb may be used as the solder alloy. Then, the substrate 10A on which the solder alloy is arranged is heated by a reflow furnace or the like. At this time, the heating temperature is higher than the melting point of the solder paste and lower than the melting point of the solder alloy. Thereby, the fusible metals 15A and 17A are formed on the substrate 10A. Thereafter, the substrate 10A is cleaned with a cleaning agent at 70 ° C. for 10 minutes to remove flux and the like contained in the solder paste.

  In the step shown in FIG. 3D, a thermosetting resin is applied by a dispenser. Then, the substrate 10A is heated at 180 degrees for 10 minutes to semi-cure the thermosetting resin. Thereby, the support portion 16A is formed on the substrate 10A.

  In addition, the formation method of the support part 16 is not limited to the process shown to FIG 3 (D). For example, a thermosetting resin formed in a predetermined shape in advance may be formed on the flat surface of the substrate 10A.

  Structures 1A and 1B are formed by repeating the steps shown in FIGS.

  The structures 1A and 1B may be formed in parallel. Alternatively, the structures 1A and 1B may be obtained by forming a large number of structures 1A on a large substrate and cutting the large substrate for each structure 1A. Moreover, when the structures 1A and 1B have different structures, either may be formed first.

  In the step shown in FIG. 3E, the structure 1B is arranged on the structure 1A so that the end surface of the support portion 16A and the end surface of the support portion 16B are aligned. Then, the structural bodies 1A and 1B are heated at 180 ° C. for 60 minutes, and the semi-cured support portions 16A and 16B are finally cured in FIG. Thereby, the support portions 16A and 16B are integrated to form the support portion 16. Furthermore, the structures 1A and 1B are heated by a reflow furnace or the like, and the contact surfaces of the fusible metals 17A and 17B are joined by solder paste or the like. At this time, the heating temperature is higher than the melting point of the solder paste and lower than the melting point of the solder alloy. Thereby, the fusible metal 17 is formed.

  In the step shown in FIG. 3F, the external connection electrodes 12A and 12B are formed by metal plating or the like.

  Through the above steps, the fuse 1 can be manufactured.

  Next, a fuse according to a second embodiment of the present invention will be described. The appearance of the fuse according to the second embodiment is the same as that of FIG. FIG. 4 is a cross-sectional view taken along the line A-A ′ of the fuse according to the second embodiment. A current path from the outside to the heater electrode 46 is not shown.

  The fuse 41 according to the second embodiment includes an electrode 44A, a resin film 45, and a heater electrode 46. Other configurations are the same as those of the first embodiment. Hereinafter, differences from the first embodiment will be described.

  The electrode 44A, the resin film 45, and the heater electrode 46 are laminated in the order of the heater electrode 46, the resin film 45, and the electrode 44A. The resin film 45 insulates between the electrode 44 </ b> A and the heater electrode 46. The heater electrode 46 is a heating unit according to the second embodiment, and heats the electrode 44A.

  When an external current is applied to the heater electrode 46, the heater electrode 46 generates heat. The heated heater electrode 46 heats and melts the fusible metals 15A, 15B, and 17. Therefore, the current path cutting timing can be controlled by applying a current to the heater electrode 46.

  Next, an example of a method for manufacturing the fuse 41 will be described. FIG. 5 is a cross-sectional view taken along the line A-A ′ showing the manufacturing process of the fuse 41 step by step. A current path from the outside to the heater electrode 46 is not shown.

  In the step shown in FIG. 5A, a predetermined via electrode is formed inside the substrate 10A, and a predetermined wiring is formed on both surfaces of the substrate 10A. Thereby, via electrodes 13A and the like are formed on the substrate 10A.

  5B, a resistor paste such as a carbon paste is printed at a predetermined position on the substrate 10A. Then, the substrate 10A is heated at 150 ° C. for 20 minutes in an oven or the like to cure the resistor paste. Thereby, the heater electrode 46 is formed.

  In the step shown in FIG. 5C, a thermosetting resin such as an epoxy resin is applied to the surface of the resistor paste by printing. Then, the substrate 10A is heated at 180 ° C. for 60 minutes to cure the thermosetting resin. Thereby, the resin film 45 is formed on the surface of the heater electrode 46.

  In the step shown in FIG. 5D, a metal foil is thermocompression bonded to the surface of the resin film 45. Thereby, the electrode 44 </ b> A is formed on the surface of the resin film 45. The subsequent steps are the same as those in FIG.

  Through the above steps, the fuse 41 can be manufactured.

  Next, a fuse according to a third embodiment of the present invention will be described. The fuse 51 according to the third embodiment has the same configuration as the fuse 1 according to the first embodiment, but is manufactured by a different method. Hereinafter, an example of a method for manufacturing the fuse 51 will be described while referring to differences from the first embodiment.

  FIG. 6 is a cross-sectional view taken along the line A-A ′ showing one step of the method for manufacturing the fuse 51. The structure 5B is formed by the steps shown in FIGS. A structure 5A is formed by the steps shown in FIGS. The structure 5B is disposed on the structure 5A so that the fusible metal 15B and the fusible metal 17 are in contact with each other. The structural bodies 5A and 5B are heated by a reflow furnace or the like to bond the fusible metals 15B and 17 and bond the substrate 10B and the support portion 16 together. The subsequent steps are the same as those in FIG.

  Through the above steps, the fuse 41 can be manufactured.

  The configuration of the fuse according to the present invention is not limited to the above. Further, the method for manufacturing a fuse according to the present invention is not limited to the above.

1,41 Fuse 10A, 10B Substrate 12A, 12B External connection electrode 13A, 13B Via electrode 14A, 14B, 44A Electrode 15A, 15B, 17, 17A, 17B, 57A, 57B Fusible metal 16, 16A, 16B, 56A, 56B Support part 45 Resin film 46 Heater electrode

Claims (8)

A substrate,
A first electrode formed on the main surface of the substrate;
A second electrode facing the first electrode;
A support for fixing the position of the second electrode with respect to the first electrode;
A fusible metal portion positioned between the first electrode and the second electrode;
The support portion surrounds the fusible metal portion when viewed from a direction perpendicular to the main surface of the substrate,
When the fusible metal part is melted in all parts between the first electrode and the second electrode and between the support part and the fusible metal part, the fusible metal part is melted. A space for the metal part to spread is formed ,
The fuse, wherein the first electrode and the second electrode are larger than the fusible metal portion when viewed from a direction perpendicular to the main surface of the substrate . The substrate includes a first substrate and a second substrate,
The first electrode is formed on a main surface of the first substrate;
The fuse according to claim 1, wherein the second electrode is formed on a main surface of the second substrate.   The fuse according to claim 2, wherein the first substrate, the second substrate, and the support portion form a casing, and the fusible metal portion is disposed in the casing. The first substrate, the first electrode, a part of the fusible metal part, and a part of the support part form a first structure,
The second substrate, the second electrode, the other part of the fusible metal part, and the other part of the support part form a second structure,
Wherein the first structure and the second structure, a fuse according to claim 2 or 3, characterized in that it is identical. The fusible metal portion includes a plurality of fusible metals,
Wherein the plurality of fusible metal is formed in layers in a direction perpendicular to the main surface of the front Kimoto plate,
Wherein the fusible metal in contact with the first and second electrodes, the fuse according to any one of claims 1 to 4, characterized in that it has a lower than other of said fusible metal melting point. Fuse according to any one of claims 1 to 5, characterized in that it comprises a heating section for heating the fusible metal part. A first step of forming a first low melting point fusible metal on a first substrate on which a first electrode is formed;
A second step of forming a second low melting point fusible metal on the second substrate on which the second electrode is formed;
The first electrode and the second electrode are provided so as to face each other, and a support portion for fixing the position of the second electrode with respect to the first electrode is provided, and the first electrode and the second electrode are provided. and a third step of providing a refractory fusible metal between,
In the third step,
Providing the support portion so that the support portion surrounds the refractory fusible metal as viewed from a direction perpendicular to the main surface of the first substrate;
When the high melting point fusible metal is melted in all parts between the first electrode and the second electrode and between the support part and the high melting point fusible metal, Form a space for the high melting point fusible metal to spread,
It is seen from the direction perpendicular to the main surface of said first substrate, such that the first electrode and the second electrode is larger than the high-melting-point fusible metal, Rukoto provided the refractory fusible metal A method of manufacturing a fuse characterized by the above . It said refractory fusible metal is formed first and second high melting fusible metals or al,
The third step includes
Fixing the first high melting point fusible metal to the surface of the first low melting point fusible metal;
Fixing the second high melting point fusible metal to the surface of the second low melting point fusible metal;
The method for manufacturing a fuse according to claim 7, further comprising a step of bringing the first refractory metal into contact with the second refractory metal.

Images