CN118645411A - Protection components - Google Patents

Abstract

The present invention is provided with: an insulating substrate; a first electrode and a second electrode provided on one surface of the insulating substrate so as to face each other; a heating element provided on one surface of the insulating substrate; a third electrode connected to one end of the heating element; a heating element extraction electrode connected to an end portion of the heating element opposite to the one end portion; and a fuse element having one end portion facing each other connected to the first electrode, the other end portion connected to the second electrode, a central portion between the one end portion and the other end portion being in contact with the heat generating element extraction electrode, at least a part of a side surface of the first electrode facing the second electrode and an upper surface connected to the side surface being covered with a first insulating member, and at least a part of a side surface of the second electrode facing the first electrode and an upper surface connected to the side surface being covered with a second insulating member.

Description

Protection components

This application is a divisional application; the application number of the parent application is "2020800609066", and the name of the invention is "Protection Element".

Technical Field

The present invention relates to a protection element.

This application claims priority based on Japanese Patent Application No. 2019-161178 filed in Japan on September 4, 2019, the contents of which are cited herein.

Background Art

The circuit board generally has a protection element. The protection element cuts off the current path when an abnormality occurs, such as when an overcurrent exceeding the rated value occurs in the current path. As a protection element, for example, a protection element of the following structure is known, which includes: an insulating substrate; a first electrode and a second electrode, which are arranged on one surface of the insulating substrate in a mutually opposed manner; a heating element, which is arranged on one surface of the insulating substrate; a third electrode, which is connected to one end of the heating element; a heating element lead-out electrode, which is connected to the end of the heating element on the opposite side of the end connected to the third electrode; and a fuse element, one end of which is opposite to each other is connected to the first electrode, the other end is connected to the second electrode, and the center between the ends is connected to the heating element lead-out electrode (see patent document 1). In the protection element of this structure, there is a space between the first electrode and the heating element lead-out electrode and between the second electrode and the heating element lead-out electrode. Therefore, by using heat to melt the fuse element, the fuse element is blown in the space between the first electrode and the heating element lead-out electrode or in the space between the second electrode and the heating element lead-out electrode.

In the above-mentioned protection element, when an overcurrent flows between the first electrode and the second electrode, Joule heat is generated in the fuse element. The fuse element melts and blows due to the heat, thereby cutting off the current path of the circuit substrate. In addition, when an abnormality other than overcurrent occurs in the circuit substrate, current flows through the third electrode, thereby generating heat in the heating element. The heat is transferred to the fuse element via the heating element lead-out electrode, and the fuse element melts and blows. As a result, the current path of the circuit substrate is cut off.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2017-174592

Summary of the invention

Problems to be solved by the invention

With the recent increase in power and miniaturization of electronic devices, it is expected that the protection element will have a further lower resistance and be miniaturized. In order to reduce the resistance of the protection element, it is considered to increase the cross-sectional area of the fuse element. However, in this case, it is necessary to ensure a space for holding the molten fuse element, so it is difficult to miniaturize the protection element.

In addition, in order to reduce the resistance and miniaturization of the protection element, it is considered to narrow the distance between the first electrode and the heating element lead-out electrode and between the second electrode and the heating element lead-out electrode, thereby shortening the width of the fuse element. However, in this case, an internal short circuit is easily caused between the first electrode and the heating element lead-out electrode or between the second electrode and the heating element lead-out electrode.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a protection element having a structure that can easily reduce resistance and size and that is unlikely to cause an internal short circuit.

Solutions to Solve Problems

The present invention provides the following solutions in order to solve the above-mentioned problems.

(1) A protection element according to one embodiment of the present invention comprises: an insulating substrate; a first electrode and a second electrode, which are arranged on one surface of the insulating substrate in a manner opposite to each other; a heating element, which is arranged on one surface of the insulating substrate; a third electrode, which is connected to one end of the heating element; a heating element lead-out electrode, which is connected to the end of the heating element on the opposite side of the one end; and a fuse element, wherein one end of the heating element is connected to the first electrode and the other end is connected to the second electrode, and the center between the one end and the other end is connected to the heating element lead-out electrode, and at least a portion of the side surface of the first electrode opposite to the second electrode and the upper surface connected to the side surface are covered by the first insulating component, and at least a portion of the side surface of the second electrode opposite to the first electrode and the upper surface connected to the side surface are covered by the second insulating component.

(2) In the aspect described in (1) above, it is preferable that the heat generating body lead-out electrode is extended to the upper surfaces of the first insulating member and the second insulating member.

Effects of the Invention

According to the present invention, it is possible to provide a protection element having a structure that can easily reduce resistance and size and in which an internal short circuit is unlikely to occur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a protection element according to a first embodiment of the present invention.

FIG. 2 is a bottom view of the protection element according to the first embodiment of the present invention.

Fig. 3 is a cross-sectional view taken along line III-III' of Fig. 1 .

Fig. 4 is a longitudinal sectional view taken along line IV-IV' of Fig. 1 .

5 is a cross-sectional view showing a state in which the protection element according to the first embodiment operates and the fuse element is melted.

FIG. 6 is a cross-sectional view of a protection element according to a second embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a protection element according to a second embodiment of the present invention.

FIG. 8 is a plan view of a protection element according to a third embodiment of the present invention.

FIG. 9 is a bottom view of a protection element according to a third embodiment of the present invention.

Fig. 10 is a cross-sectional view taken along line X-X' of Fig. 9 .

Fig. 11 is a longitudinal sectional view taken along line XI-XI' of Fig. 9 .

FIG. 12 is a cross-sectional view of a protection element produced in Comparative Example 1. FIG.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings used in the following description, in order to facilitate understanding of the features, the features are sometimes enlarged for convenience. The dimensional ratios of the components of the drawings are sometimes different from the actual ones. The materials, dimensions, etc. illustrated in the following description are examples, and the present invention is not limited thereto, and can be implemented by appropriately changing within the scope of achieving the effects of the present invention.

First embodiment

The structure of the protection element of the first embodiment of the present invention is shown in Figures 1 to 4. Figure 1 is a top view (plan view) of the protection element. Figure 2 is a bottom view (bottom view) of the protection element. Figure 3 is a cross-sectional view along the line III-III' of Figure 1. Figure 4 is a longitudinal cross-sectional view along the line IV-IV' of Figure 1.

The protection element 1 of the first embodiment includes: an insulating substrate 10; a first electrode 11 (first upper surface electrode 11a) and a second electrode 12 (second upper surface electrode 12a) provided on the upper surface 10a of the insulating substrate 10 in a manner facing each other; a heating element 20 provided on the lower surface 10b of the insulating substrate 10; a third electrode 13 connected to one end of the heating element 20; a heating element lead-out electrode 14 connected to the end opposite to the one end of the heating element 20; and a fuse element 30 connected to the first electrode 11, the second electrode 12, and the heating element lead-out electrode 14. The first electrode 11 is connected to one end 30a of the fuse element 30 facing each other via a first terminal 18a. The second electrode 12 is connected to the other end 30b via a second terminal 18b. Furthermore, the heating element lead-out electrode 14 is connected to the center portion 30c between the end 30a and the end 30b of the fuse element 30 via a conductive member 15. The first terminal 18 a and the fuse element 30 , the second terminal 18 b and the fuse element 30 , and the conductive member 15 and the fuse element 30 are bonded together by solder paste 32 .

The insulating substrate 10 is not particularly limited as long as it is made of an insulating material, and for example, in addition to substrates used for printed wiring boards such as ceramic substrates and glass epoxy substrates, glass substrates, resin substrates, insulating metal substrates, etc. can also be used. It should be noted that among them, an insulating substrate excellent in heat resistance and thermal conductivity, that is, a ceramic substrate, is preferred.

The first electrode 11 is composed of a first upper surface electrode 11a, a first lower surface electrode 11b and a first conductive portion 11c. The first upper surface electrode 11a is formed on the upper surface 10a of the insulating substrate 10. The side surface of the first upper surface electrode 11a opposite to the second upper surface electrode 12a and at least a portion of the upper surface connected to the side surface are covered by the first insulating component 17a. The portion of the first upper surface electrode 11a not covered by the first insulating component 17a is covered by the first terminal 18a. The first lower surface electrode 11b is formed on the lower surface 10b of the insulating substrate 10. The first lower surface electrode 11b is connected to the wiring of the circuit substrate. The first conductive portion 11c penetrates the insulating substrate 10 and electrically connects the first upper surface electrode 11a and the first lower surface electrode 11b.

The second electrode 12 is composed of a second upper surface electrode 12a, a second lower surface electrode 12b and a second conductive portion 12c. The second upper surface electrode 12a is formed on the upper surface 10a of the insulating substrate 10. The side surface of the second upper surface electrode 12a opposite to the first upper surface electrode 11a and at least a portion of the upper surface connected to the side surface are covered by the second insulating component 17b. The portion of the second upper surface electrode 12a not covered by the second insulating component 17b is covered by the second terminal 18b. The second lower surface electrode 12b is formed on the lower surface 10b of the insulating substrate 10. The second lower surface electrode 12b is connected to the wiring of the circuit substrate. The second conductive portion 12c penetrates the insulating substrate 10 and electrically connects the second upper surface electrode 12a and the second lower surface electrode 12b.

The third electrode 13 is connected to one end of the heating element 20. A portion of the third electrode 13 is covered by the heat insulating member 21. The portion of the third electrode 13 not covered by the heat insulating member 21 is connected to a switching element of the circuit board. The switching element operates when an abnormality other than overcurrent occurs in the circuit board, and supplies current to the third electrode 13.

Metal materials such as Ag and Cu can be used as materials constituting the first electrode 11, the second electrode 12, and the third electrode 13. The surfaces of the first electrode 11, the second electrode 12, and the third electrode 13 may be covered with metals such as Ag, Ag-Pt, Ag-Pd, Au, Ni-Au, or alloys.

The heating element 20 has a relatively higher resistance than the third electrode 13. The heating element 20 is formed of a high-resistance conductive material that easily generates heat when electricity is passed through it. As a material constituting the heating element 20, ruthenium oxide or carbon black can be used.

The heat generating element 20 is covered with a heat insulating member 21. As a material of the heat insulating member 21, for example, an insulating material such as ceramics or glass can be used.

The heating body lead-out electrode 14 is composed of a heating body lead-out upper surface electrode 14a, a heating body lead-out lower surface electrode 14b, and a heating body lead-out electrode conductive portion 14c. The heating body lead-out upper surface electrode 14a is formed on the upper surface 10a of the insulating substrate 10. A conductive component 15 is stacked on the upper surface of the heating body lead-out upper surface electrode 14a. The heating body lead-out lower surface electrode 14b is formed on the lower surface 10b of the insulating substrate 10 and is connected to the heating body 20. The heating body lead-out electrode conductive portion 14c passes through the insulating substrate 10 to electrically connect the heating body lead-out upper surface electrode 14a and the heating body lead-out lower surface electrode 14b.

The heating element lead-out electrode 14 and the conductive member 15 preferably have high thermal conductivity and electrical conductivity. Metal materials such as Ag and Cu can be used as materials constituting the heating element lead-out electrode 14 and the conductive member 15. The surfaces of the heating element lead-out electrode 14 and the conductive member 15 may also be covered with metals or alloys such as Ag, Ag-Pt, Ag-Pd, Au, and Ni-Au.

A space 19a is formed between the heating element lead-out upper surface electrode 14a and the first terminal 18a. In addition, a space 19b is formed between the heating element lead-out upper surface electrode 14a and the second terminal 18b. The first upper surface electrode 11a below the space 19a is covered by the first insulating component 17a. The second upper surface electrode 12a below the space 19b is covered by the second insulating component 17b. Therefore, even if the heating element lead-out upper surface electrode 14a is extended to the upper surface of the first insulating component 17a, especially to the position where the heating element lead-out upper surface electrode 14a overlaps with the first upper surface electrode 11a via the first insulating component 17a, it is not easy to cause an internal short circuit. Similarly, even if the heating element lead-out upper surface electrode 14a is extended to the upper surface of the second insulating component 17b, especially to the position where the heating element lead-out upper surface electrode 14a overlaps with the first upper surface electrode 11a via the second insulating component 17b, it is not easy to cause an internal short circuit. Therefore, the widths of the space 19a and the space 19b can be narrowed. The width Wa of the space 19a and the width Wb of the space 19b are preferably within a range of 0.02 mm or more and 1.0 mm or less, respectively.

As long as the fuse element 30 can be melted by heat, the structure and material are not particularly limited. The fuse element 30 may also be a metal monomer. The fuse element 30 may also be a laminated body with a high melting point metal layer having a relatively high melting point on the outside and a low melting point metal layer having a relatively low melting point on the inside.

In the case where the fuse element 30 is a metal monomer, In, Pb, Ag, Cu or an alloy with any of them as the main component can be used as its material. In the case of a laminate, the low melting point metal layer preferably has a melting point in the range of above the heating temperature (usually about 220°C) during the reflow soldering performed when the protection element 1 is installed and below 280°C. The material of the low melting point metal layer is preferably tin or a tin alloy with tin as the main component. The tin content of the tin alloy is preferably 40% by mass or more, and more preferably 60% by mass or more. As examples of tin alloys, Sn-Bi alloys, In-Sn alloys, and Sn-Ag-Cu alloys can be cited. The high melting point metal layer is a layer composed of a metal material dissolved in the melt of the low melting point metal layer. In the case where the material of the low melting point metal layer is tin or a tin alloy, the material of the high melting point metal layer is preferably silver or an alloy with silver as the main component. The silver content of the silver alloy is preferably 40% by mass or more, and more preferably 60% by mass or more. As examples of silver alloys, Ag-Pd alloys can be cited.

Fig. 5 is a cross-sectional view showing a state where the protection element of the first embodiment operates and the fuse element is melted. The cross-sectional view of Fig. 5 is a cross-sectional view taken along the line III-III' of Fig. 3 at the same position.

If an overcurrent flows through the wiring of the circuit substrate, the overcurrent flows through the fuse element 30 via the first electrode 11 and the first terminal 18a and the second electrode 12 and the second terminal 18b of the protection element 1. When an overcurrent flows through the fuse element 30, Joule heat is generated in the fuse element 30. The fuse element 30 melts and blows due to the heat, so that the current path of the circuit substrate is cut off. In addition, when an abnormality other than overcurrent occurs in the circuit substrate, the current flows through the third electrode 13, thereby the heating element 20 generates heat. The heat is transferred to the fuse element 30 via the heating element lead-out electrode 14, and the fuse element 30 melts and blows, so that the current path of the circuit substrate is cut off. The melted fuse element molten solidified product 31 is held on the solder paste 32.

Next, a method for manufacturing the protection element 1 will be described.

The protection element 1 can be produced, for example, as follows.

First, the insulating substrate 10 is prepared.

On the prepared insulating substrate 10 , the first conductive portion 11 c of the first electrode 11 , the second conductive portion 12 c of the second electrode 12 , and the heat generating body lead-out electrode conductive portion 14 c are formed.

Next, a first upper surface electrode 11a is formed around the first conductive portion 11c of the upper surface 10a of the insulating substrate 10, and a second upper surface electrode 12a is formed around the second conductive portion 12c. Furthermore, a heating element lead-out upper surface electrode 14a is formed between the first upper surface electrode 11a and the second upper surface electrode 12a. In addition, a first lower surface electrode 11b is formed around the first conductive portion 11c of the lower surface 10b of the insulating substrate 10, and a second lower surface electrode 12b is formed around the second conductive portion 12c. Furthermore, a heating element lead-out lower surface electrode 14b is formed around the heating element lead-out electrode conductive portion 14c of the lower surface 10b of the insulating substrate 10. A third electrode 13 is formed at a position opposite to the heating element lead-out lower surface electrode 14b.

These electrodes can be formed by known methods used as electrode forming methods, such as printing, plating, vapor deposition, sputtering, etc. The printing method is a method of printing a metal or alloy paste for electrode formation in a desired pattern and firing it as needed.

Next, the heating element 20 is formed on the lower surface 10b of the insulating substrate 10. The heating element 20 is formed so that one end is connected to the third electrode 13 and the other end is connected to the heating element lead-out lower surface electrode 14b. Next, the heating element 20 is covered with a heat insulating member 21.

The heating element 20 can be formed, for example, by applying a high-resistance conductive paste containing a high-resistance conductive material and an adhesive, and firing it as needed. As an adhesive, an inorganic adhesive such as water glass or an organic adhesive such as a thermosetting resin can be used. In addition, the heating element 20 can be formed by a known method used as a formation method of a conductive film, such as a plating method, a vapor deposition method, and a sputtering method. In addition, as a formation method of the heating element 20, a method of pasting or laminating a high-resistance conductive film obtained by the above method can also be used.

The heat insulating member 21 can be formed by a known method used as a method for forming an electrode, such as printing, plating, vapor deposition, sputtering, etc. The printing method is a method of printing a paste of the heat insulating member in a desired pattern and firing it as needed.

Next, a first insulating component 17a is formed on the side surface of the first upper surface electrode 11a that is opposite to the second upper surface electrode 12a and a portion of the upper surface connected to the side surface. A first terminal 18a is formed on the portion of the first upper surface electrode 11a where the first insulating component 17a is not formed. Similarly, a second insulating component 17b is formed on the side surface of the second upper surface electrode 12a that is opposite to the first upper surface electrode 11a and a portion of the upper surface connected to the side surface. A second terminal 18b is formed on the portion of the second upper surface electrode 12a where the second insulating component 17b is not formed. In addition, there is no particular restriction on the order in which the first insulating component 17a and the first terminal 18a and the second insulating component 17b and the second terminal 18b are formed. The first terminal 18a and the second terminal 18b may also be formed before the first insulating component 17a and the second insulating component 17b.

The first insulating member 17a and the second insulating member 17b can be formed by, for example, a printing method. The printing method is a method of printing an insulating material paste in a desired pattern and firing it as necessary.

The first terminal 18a and the second terminal 18b can be formed by a known method used as a method for forming electrodes, such as printing, plating, vapor deposition, or sputtering. The printing method is a method of printing a metal or alloy paste for forming terminals in a desired pattern and firing it as needed.

Next, the conductive member 15 is formed on the upper surface of the heating element lead-out upper surface electrode 14a. The conductive member 15 can be formed by a known method used as a method for forming an electrode, such as printing, plating, vapor deposition, or sputtering.

The fuse element 30 is stacked on the upper surfaces of the first terminal 18a, the conductive member 15 and the second terminal 18b. The fuse element 30 can be stacked by applying solder paste 32 on the upper surfaces of the first terminal 18a, the conductive member 15 and the second terminal 18b and then placing the fuse element 30 on the solder paste 32.

According to the protection element 1 of the present embodiment constructed as above, since the first upper surface electrode 11a and the second upper surface electrode 12a are covered by the first insulating part 17a and the second insulating part 17b respectively, it is difficult to cause an internal short circuit even if the width Wa of the space 19a and the width Wb of the space 19b are narrowed. Therefore, the protection element 1 of the present embodiment is easy to be miniaturized. In addition, by narrowing the width Wa of the space 19a and the width Wb of the space 19b, the width of the fuse element 30 can be shortened, so that the resistance between the first electrode 11 and the second electrode 12 of the protection element 1 can be reduced. Therefore, the protection element 1 of the present embodiment is easy to be low-resistance and miniaturized, and is not easy to cause an internal short circuit.

[Second Embodiment]

The structure of the protection element of the second embodiment of the present invention is shown in Figures 6 and 7. Figure 6 is a cross-sectional view of the protection element of the second embodiment of the present invention, and Figure 7 is a longitudinal cross-sectional view of the protection element. The cross-sectional view of Figure 6 is equivalent to the cross-sectional view along the line III-III' of Figure 3, and the longitudinal cross-sectional view of Figure 7 is equivalent to the longitudinal cross-sectional view along the line IV-IV of Figure 4.

In the protection element 2 of the second embodiment, the heating element lead-out upper surface electrode 14d is set to a shape in which the heating element lead-out upper surface electrode 14a of the protection element 1 of the first embodiment and the conductive component 15 are integrated, and is connected to the fuse element 30 without passing through the conductive component 15. In this regard, the protection element 2 of the second embodiment is different from the protection element 1 of the first embodiment. In addition, the common parts of the protection element 2 of the second embodiment and the protection element 1 of the first embodiment are marked with the same symbols and the description is omitted.

The protection element 2 can be manufactured in the same manner as the protection element 1 of the first embodiment except for the following points, for example.

The heat generating element lead-out upper surface electrode 14 a is not formed on the upper surface 10 a of the insulating substrate 10 .

A heating element lead-out upper surface electrode 14d is formed on the upper surface 10a of the insulating substrate 10 instead of forming the conductive component 15. The heating element lead-out upper surface electrode 14d can be formed by a known method used as an electrode forming method, such as printing, plating, evaporation, sputtering, etc.

According to the protection element 2 of the present embodiment constructed as above, since the first upper surface electrode 11a and the second upper surface electrode 12a are covered by the first insulating component 17a and the second insulating component 17b respectively, it is easy to reduce resistance and miniaturize, and it is not easy to cause internal short circuit, as with the protection element 1 of the first embodiment. In addition, since the upper surface electrode 14d of the heating element is connected to the fuse element 30 without passing through the conductive component 15, the heat generated by the heating element 20 can be more efficiently transferred to the fuse element 30. Therefore, according to the protection element 2, the melting speed when the current flows through the third electrode 13 can be made faster.

[Third Embodiment]

The structure of the protection element of the third embodiment of the present invention is shown in Figures 8 to 11. Figure 8 is a top view (plan view) of the protection element, and Figure 9 is a bottom view (bottom view) of the protection element. Figure 10 is a cross-sectional view taken along the line X-X' of Figure 8, and Figure 11 is a longitudinal cross-sectional view taken along the line XI-XI' of Figure 8. In addition, the same reference numerals are used for the common parts of the protection element 3 of the third embodiment and the protection element 1 of the first embodiment, and the description thereof is omitted.

In the protection element 3 of the third embodiment, the heating element 20 is provided on the upper surface 10a of the insulating substrate 10. The heating element 20 is covered by a heat insulating member 21. The heat insulating member 21 covers the side surface of the first upper surface electrode 11a opposite to the second upper surface electrode 12a and a portion of the upper surface connected to the side surface, and the side surface of the second upper surface electrode 12a opposite to the first upper surface electrode 11a and a portion of the upper surface connected to the side surface. That is, the heat insulating member 21 also functions as an insulating member that insulates the first upper surface electrode 11a from the second upper surface electrode 12a.

One end of the heating element 20 is connected to the third electrode 13. The third electrode 13 is composed of a third upper surface electrode 13a, a third lower surface electrode 13b and a third conductive portion 13c. The third upper surface electrode 13a is formed on the upper surface 10a of the insulating substrate 10. The third upper surface electrode 13a is connected to one end of the heating element 20. The third lower surface electrode 13b is formed on the lower surface 10b of the insulating substrate 10. The third lower surface electrode 13b is connected to the switching element of the circuit substrate. The third conductive portion 13c passes through the insulating substrate 10 to electrically connect the third upper surface electrode 13a and the third lower surface electrode 13b.

The end of the heating element 20 opposite to the third lower surface electrode 13b is connected to the heating element lead-out electrode 14. The heating element lead-out electrode 14 is led to the upper surface of the heat insulating member 21. The heating element lead-out electrode 14 is connected to the fuse element 30 via solder paste 32.

Next, a method for manufacturing the protection element 3 will be described.

The protection element 3 can be produced, for example, as follows.

First, the insulating substrate 10 is prepared.

The first conductive portion 11 c of the first electrode 11 , the second conductive portion 12 c and the third conductive portion 13 c of the second electrode 12 are formed on the prepared insulating substrate 10 .

Next, the first upper surface electrode 11a is formed around the first conductive portion 11c of the upper surface 10a of the insulating substrate 10, and the second upper surface electrode 12a is formed around the second conductive portion 12c. Furthermore, the third upper surface electrode 13a is formed around the third conductive portion 13c of the upper surface 10a of the insulating substrate 10, and the third lower surface electrode 13b is formed around the third conductive portion 13c of the lower surface 10b.

Next, a heat insulating component layer having a width equal to or wider than that of the heating element 20 is formed between the first upper surface electrode 11a and the second upper surface electrode 12a on the upper surface 10a of the insulating substrate 10. Next, the heating element 20 is formed on the heat insulating component layer. The heating element 20 is formed in such a way that one end is connected to the third upper surface electrode 13a.

Next, a first terminal 18a is formed on a side surface of the first upper surface electrode 11a that is not opposite to the second upper surface electrode 12a and a portion of the upper surface connected to the side surface. A second terminal 18b is formed on a side surface of the second upper surface electrode 12a that is not opposite to the first upper surface electrode 11a and a portion of the upper surface connected to the side surface. Next, a heat insulating member 21 is formed between the first upper surface electrode 11a and the second upper surface electrode 12a.

Next, the heat-generating body lead-out electrode 14 is formed on the upper surface of the heat-insulating member 21. The heat-generating body lead-out electrode 14 is formed so that one end thereof is connected to the heat-generating body 20.

Then, the fuse element 30 is stacked on the upper surfaces of the first terminal 18 a , the heat-generating body lead-out electrode 14 , and the second terminal 18 b using the solder paste 32 .

According to the protection element 3 constructed as above, since the first upper surface electrode 11a and the second upper surface electrode 12a are respectively covered by the heat insulating member 21, it is a structure that is easy to reduce resistance and miniaturize, and is difficult to cause internal short circuit, similar to the protection element 1 of the first embodiment. In addition, since the heating element 20 is arranged on the upper surface 10a side of the insulating substrate 10, the heat generated by the heating element 20 can be more efficiently transferred to the fuse element 30. Therefore, the melting speed when the current flows through the third electrode 13 can be further accelerated.

Example

Next, the present invention will be described by way of examples.

[Example 1]

The protection element 1 of the first embodiment was produced. The constituent materials of each member are as follows.

Insulating substrate 10: Alumina substrate, length: 2mm, width: 4mm, thickness: 0.2mm

First electrode 11: Ag whose surface is covered by Ni-Au plating

Second electrode 12: Ag whose surface is covered by Ni-Au plating

Third electrode 13: Ag whose surface is covered by Ni-Au plating

Heater lead-out electrode 14: Ag coated with Ni-Au on the surface

Conductive member 15: Ag whose surface is covered by Ni-Au plating

First insulating member 17a, second insulating member 17b: glass

First terminal 18a, second terminal 18b: Silver

Total width of space 19a and space 19b (Wa+Wb): 0.5 mm

Heating element 20: Ruthenium oxide

Fuse element 30: A laminated body using Ag as the high melting point metal layer on the outside and Sn alloy as the low melting point metal layer on the inside, length: 1.6 mm, width: 2.0 mm, thickness: 0.6 mm

Solder paste 32: Sn alloy

(evaluate)

The resistance value between the first electrode 11 and the second electrode 12 of the fuse element 30 of the protection element 1 was measured. In addition, the time from when the power of 11 W and the power of 12 W were supplied to the third electrode 13 until the fuse element 30 was blown was measured. These results are shown in Table 1 together with the longitudinal and lateral dimensions of the fuse element 30 and the total width of the space 19a and the space 19b.

[Example 2]

A protection element 2 of the second embodiment was produced in the same manner as in Example 1 except that a heat generating element lead-out upper surface electrode 14d was formed instead of the heat generating element lead-out upper surface electrode 14a and the conductive member 15. The obtained protection element 2 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]

The protection element 3 of the third embodiment was produced using the same materials as in Example 1. The obtained protection element 3 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]

12 is a cross-sectional view of a protection element produced in Comparative Example 1. The protection element 4 produced in Comparative Example 1 is different from the protection element 1 produced in Example 1 in the following respects.

The first insulating component 17a is not formed on the upper surface of the first upper surface electrode 11a, and the second insulating component 17b is not formed on the upper surface of the second upper surface electrode 12a. The conductive component 15 covers the periphery of the heating element lead-out upper surface electrode 14a. The width of the conductive component 15 is the same as that of the protection element 1 of Example 1. In addition, the position of the first upper surface electrode 11a is offset to the outside by 0.5mm in such a way that the width Wa of the space 19a between the conductive component 15 and the first upper surface electrode 11a is 0.25mm. The position of the second upper surface electrode 12a is offset to the outside by 0.5mm in such a way that the width Wa of the space 19b between the conductive component 15 and the second upper surface electrode 12a is 0.25mm. Thus, the total width (Wa+Wb) of the space 19a and the space 19b is 0.5mm, which is the same as that of the protection element 1, but the width of the fuse element 30 is 3mm, which is 1mm wider than that of the protection element 1. The obtained protection element 4 was evaluated in the same way as in Example 1. The results are shown in Table 1.

[Table 1]

As shown in Table 1, the resistance between the first electrode 11 and the second electrode 12 of the protection elements 1 to 3 of Examples 1 to 3 is smaller than that of the protection element 4 of Comparative Example 1. This is probably because the width of the fuse element 30 is narrowed, and the distance between the first electrode 11 and the second electrode 12 is shortened.

In addition, the protection element 2 of Example 2, in which the heat-generating body lead-out upper surface electrode 14d is formed instead of separately forming the heat-generating body lead-out upper surface electrode 14a and the conductive component 15, has a shorter melting time when current flows through the third electrode 13 than the protection element 1 of Example 1, and the melting speed becomes faster.

The protection element 3 of Example 3 in which the heating element 20 is arranged on the upper surface 10 a side of the insulating substrate 10 has a shorter melting time when a current flows through the third electrode 13 than the protection element 2 of Example 2, and the melting speed is further increased.

Explanation of symbols

1, 2, 3—protection element, 10—insulating substrate, 10a—upper surface, 10b—lower surface, 11—first electrode, 11a—first upper surface electrode, 11b—first lower surface electrode, 11c—first conductive portion, 12—second electrode, 12a—second upper surface electrode, 12b—second lower surface electrode, 12c—second conductive portion, 13—third electrode, 13b—third lower surface electrode, 13c—third conductive portion, 14—heating element lead-out electrode, 14a, 14d—heating element lead-out upper surface electrode, 14b—heating element lead-out lower surface electrode, 14c—heating element lead-out electrode conductive portion, 15—conductive component, 17a—first insulating component, 17b—second insulating component, 18a—first terminal, 18b—second terminal, 19a, 19b—space, 20—heating element, 21—insulating component, 30—fuse element, 30a, 30b—ends, 30c—central portion, 31—molten solidified product of fuse element, 32—solder paste.

Claims (2)

1. A protective element, comprising:

An insulating substrate;

A first electrode and a second electrode provided on one surface of the insulating substrate so as to face each other;

A heating element provided on the other surface of the insulating substrate;

a third electrode connected to one end of the heating element;

a heat-generating-element extraction electrode provided on one surface of the insulating substrate; and

A fuse element having one end portion connected to the first electrode and the other end portion connected to the second electrode, wherein a central portion between the one end portion and the other end portion is in contact with the heat-generating element extraction electrode,

One end of the heat-generating body extraction electrode is connected to an end of the heat-generating body opposite to the one end,

At least a part of a side surface of the first electrode facing the second electrode and an upper surface connected to the side surface is covered with a first insulating member,

At least a part of a side surface of the second electrode facing the first electrode and an upper surface connected to the side surface is covered with a second insulating member,

One end of the heat-generating body extraction electrode is disposed so as to overlap a portion of the first electrode, and the other end of the heat-generating body extraction electrode is disposed so as to overlap a portion of the second electrode, in the thickness direction of the insulating substrate.

2. The protective member as claimed in claim 1, wherein,

The heat-generating body extraction electrode extends to the upper surface of the first insulating member and the second insulating member.