JP6711704B2 - Protective device with bypass electrode - Google Patents

Description

The present invention relates to a circuit protection element for electric/electronic equipment.

2. Description of the Related Art In recent years, with the rapid spread of small electronic devices such as mobile devices, small and thin protective elements have been used as protective elements to be mounted in a protective circuit of a power supply to be mounted. For the protection circuit of the secondary battery pack, for example, a protection element for a surface mount component (SMD) as described in Patent Document 1 is preferably used. These protective elements detect abnormal conditions such as excessive heat generation and overvoltage caused by overcurrent of the protected equipment, or respond to abnormal overheating of the ambient temperature, and activate a fuse under a predetermined condition to cut off the electric circuit. There is a non-recoverable protection element. In order to ensure the safety of the equipment, the protection element causes the resistance element to generate heat by a signal current when the protection circuit detects an abnormality that occurs in the equipment, and the heat generation melts the fuse element made of a fusible alloy material to fuse the circuit. Or the fuse element is blown by an overcurrent to break the circuit.

According to Patent Document 1, there is a protective element using a fuse element material formed by laminating a low-melting metal material that melts at a soldering temperature and a low-melting metal material and a soluble metal structural material. The fuse element material of this protective element is to hold the low melting point metal material that has been liquefied in the soldering work by interfacial tension so that it does not melt for a certain period of time by adhering it to the solid phase metal structural material at that temperature. Thus, the shape of the fuse element is maintained at least during the soldering work to prevent the fuse element material from malfunctioning at the soldering work temperature. When the soldering is completed and the circuit protection element is mounted on the protected circuit, the metal structural material of the fuse element material is diffused or melted in the low melting point metal material that is the medium by the heat of soldering, so it becomes diluted. Further, it easily disappears due to abnormal overheating of the installation environment or heating of the built-in resistance heating element by the heater, and thereafter it operates without hindering fusing.

Japanese Unexamined Patent Application Publication No. 2015-079608

However, the above-mentioned protective element uses a fuse element material in which a metal structure material of silver or copper is laminated on a low melting point metal material of a tin-based solder alloy, but when the metal structure material dissolves in the low melting point metal material, the diffusion interface is formed. An intermetallic compound of silver or copper is produced. Therefore, there is a drawback that the high resistance intermetallic compound layer generated at the interface serves as a barrier and increases the electrical resistance of the protective element.

The present invention has been proposed in order to solve the above-mentioned problems, and in a surface mount type circuit protection device, even if a high resistance layer of an intermetallic compound is formed at a diffusion interface while having reflow resistance. It is an object of the present invention to provide a protection element whose internal resistance value does not increase.

According to the present invention, an insulating substrate, a plurality of pattern electrodes provided on the insulating substrate, a bypass electrode made of a low resistance material which electrically connects predetermined pattern electrodes, and a bridge electrode between the pattern electrodes And a fuse element provided close to the fuse element, wherein the bypass electrode is provided on the insulating substrate, has a higher melting temperature than the fuse element, and is made of a metal material that is soluble in the melted fuse element. Provided is a protection element with a bypass electrode. If necessary, a resistance heating element is provided on the insulating substrate of the protection element with the bypass electrode. The bypass electrode of the present invention comprises a sintered electrode formed by sintering a specific metal paste used for the internal electrode of the laminated ceramic substrate. The metal paste for the bypass electrode is characterized in that the glass frit content is not added or is less than 2% by mass. The term "proximity" as used herein means that the fused fuse element is close enough to quickly infiltrate the bypass electrode, and the fuse element is provided near the bypass electrode even when the fuse element is in contact with the bypass electrode ( For example, the bypass electrode may be covered with a fuse element so that there is a gap between the fuse element and the bypass electrode.

The protection element with a bypass electrode according to the present invention has a bypass electrode provided on an insulating substrate, and the bypass electrode is made of a metal having a higher melting temperature than the fuse element, and the molten fuse element wets the bypass electrode at the same time. Although the bypass electrode is melted, the liquid-phase fuse element is attached and held by utilizing the wetting of the solid-liquid interface so as not to melt for a certain period of time until the soldering work is completed with the solid-phase bypass electrode. Therefore, the shape of the fuse element can be maintained at least during the soldering work to prevent the fuse element from malfunctioning at the soldering work temperature.

Furthermore, since the bypass electrode of the present invention is formed by sintering a metal paste, it is a porous electrode material with many sponge-like cavities, and a fuse element in a liquid phase is quickly permeated to form a three-dimensional shape in the depth direction. After the protective element is reflow-soldered, the fuse element is quickly melted by reheating. Moreover, even if a high-resistance intermetallic compound layer is formed at the interface with the fuse element that has infiltrated the bypass electrode, the remaining bypass electrode is left in the middle of the intermetallic compound until the bypass electrode is dissolved (that is, the protective element operates). Since the conductive path between the pattern electrodes is maintained without interposing the layer, the internal resistance of the protective element is prevented from increasing.

The perspective view which decomposed|disassembled the component member of the protection element 10 with a bypass electrode which concerns on this invention is shown. It is the protection element 20 with a bypass electrode which concerns on this invention, (a) shows the top view which cut|disconnected the lid|cover along the d-d line of (b), (b) shows the D-D line of (a). FIG. 3C is a cross-sectional view taken along the line, and FIG. It is the protection element 30 with a bypass electrode which concerns on this invention, (a) shows the top view which cut|disconnected the lid body along the dd line of (b), (b) shows the D-D line of (a). FIG. 3C is a cross-sectional view taken along the line, and FIG.

As shown in FIG. 1, a protection element 10 with a bypass electrode according to the present invention includes an insulating substrate 11, a plurality of pattern electrodes 12 made of copper, silver, a copper alloy, and a silver alloy, which are provided on the insulating substrate 11, and a predetermined pattern. The bypass electrode 13 made of a low-resistance material such as copper, silver, copper alloy, or silver alloy electrically connected between the pattern electrodes 12 and the predetermined pattern electrode 12 are bridged and close to the bypass electrode 13. The bypass electrode is provided with at least one fuse element 14 provided, an operating flux (not shown) applied to the surface of the fuse element 14, and a lid 15 that covers the upper portion of the fuse element 14 together with the operating flux. 13 is provided on the insulating substrate 11, has a melting temperature higher than that of the fuse element 14, and is made of a metal material that is soluble in the melted fuse element 14. The bypass electrode 13 of the present invention is a sintered electrode formed by sintering a metal paste used for an internal electrode of a laminated ceramic substrate, and the bypass electrode metal paste does not contain a glass frit content. It is characterized by using less than 2% by mass. If the glass frit content exceeds 2% by mass, the glass material hinders the melting of the bypass electrode 13 and the permeation of the fused fuse element 14, so that the unmelted portion of the bypass electrode 13 is likely to occur. On the other hand, the pattern electrode 12 of the present invention is not particularly limited in material and the like. For example, the patterned electrode 12 of the present invention may be formed by sintering using the above-mentioned metal paste for a bypass electrode to have the same structure as the bypass electrode 13, or another conductive material that is not melted in the fused fuse element. Can also be selected. As an example, sintering is performed using another metal paste containing more glass frit than the metal paste for the bypass electrode (that is, containing 2% by mass or more, preferably 2 to 5% by mass of the glass frit). Alternatively, the pattern electrode 12 may be sintered and formed using the same metal paste for the bypass electrode, and only the pattern electrode 12 may be further covered with a coating material having a barrier property such as nickel that does not dissolve in the molten fuse element. The insulating substrate 11 of the protection element 10 with the bypass electrode is made of a heat-resistant insulating plate, for example, a glass epoxy substrate, a ceramics substrate, a glass substrate, or the like. Good. An insulation coating is applied to the resistance heating element as needed. When the resistance heating element is not provided, the central electrode of the pattern electrodes 12 connected to the fuse element 14 may be omitted. The lid 14 may cover the upper portions of the insulating substrate 11 and the fuse element 14 to secure a desired cavity space, and does not limit the shape or material. For example, for the lid body 14, a dome-shaped resin film cover, a plastic lid, a ceramics lid, or the like can be preferably used.

As shown in FIG. 2, the protection element 20 with a bypass electrode according to the present invention includes an insulating substrate 21, a plurality of pattern electrodes 22 made of copper, silver, a copper alloy, and a silver alloy, which are provided on the insulating substrate 21, and a predetermined pattern. The bypass electrode 23 made of a low resistance material such as copper, silver, copper alloy, or silver alloy electrically connected between the pattern electrodes 22 and the predetermined pattern electrode 22 are bridged and close to the bypass electrode 23. The bypass electrode 23 is provided with at least one fuse element 24 provided, an operating flux (not shown) applied to the surface of the fuse element 24, and a lid 25 that covers the upper portion of the fuse element 24 together with the operating flux. Is provided on the insulating substrate 21, has a higher melting temperature than the fuse element 24, and is made of a metal material that is soluble in the melted fuse element 24. The insulating substrate 21 of the protection element 20 with the bypass electrode is made of a heat resistant insulating plate, for example, a glass epoxy substrate, a ceramics substrate, a glass substrate or the like, and the resistance heating element 26 is provided on one surface of the insulating substrate 21. The resistance heating element 26 is provided with an insulating coating (not shown). The resistance heating element 26 may be provided on the other plate surface different from the mounting surface of the fuse element 24 as shown in FIG. 2, or may be provided on the same plate surface as the fuse element 34 as shown in FIG. May be. The lid body 25 may cover the upper portions of the insulating substrate 21 and the fuse element 24 to secure a desired cavity space, and does not limit the shape or material. For example, as the lid 25, a dome-shaped resin film cover, a plastic lid, a ceramics lid, or the like can be preferably used.

As shown in FIG. 2, a protective element 20 with a bypass electrode according to the first embodiment of the present invention includes an alumina/ceramic insulating substrate 21 and a plurality of silver alloy pattern electrodes 22 provided on the upper and lower surfaces of the insulating substrate 21. A resistance heating element 26 electrically connected to a predetermined pattern electrode 22 and provided on the lower surface of the insulating substrate 21, a silver bypass electrode 23 electrically connecting the predetermined pattern electrodes 22, and a predetermined pattern electrode 22. A fuse element 24 provided between the fuse electrode 24 and the bypass electrode 23 in a bridge manner, an operating flux (not shown) applied to the surface of the fuse element 24, and an upper portion of the fuse element 24 together with the operating flux. And a lid 25 made of liquid crystal polymer fixed to the insulating substrate 21, the bypass electrode 23 is provided on the upper surface of the insulating substrate 21, has a higher melting temperature than the fuse element 24, and is soluble in the melted fuse element 24. The pattern electrode 22 has a silver alloy half through hole 27 for electrically connecting the pattern electrodes 22 on the upper and lower surfaces of the substrate. Although not particularly shown, the surface of the resistance heating element 26 of Example 1 is glass overglaze.

A protection element 30 with a bypass electrode according to a second embodiment of the present invention is a modification of the circuit protection element 20 of the first embodiment. As shown in FIG. 3, an insulating substrate 31 made of alumina/ceramics and this insulating substrate 31 are used. The plurality of silver alloy pattern electrodes 32 provided on the upper and lower surfaces, the resistance heating element 36 electrically connected to the predetermined pattern electrode 32 and provided on the upper surface of the insulating substrate 31, and the predetermined pattern electrode 32 are electrically connected. A bypass electrode 33 made of a silver alloy, a fuse element 34 provided between the predetermined pattern electrode 32 and the fuse electrode 34 in the vicinity of the bypass electrode 33, and an operating flux (not shown) applied to the surface of the fuse element 34. ) And a lid 35 made of liquid crystal polymer that covers the upper portion of the fuse element 34 together with the operating flux and is fixed to the insulating substrate 31, and the bypass electrode 33 is provided on the upper side of the insulating substrate 31. Also has a high melting temperature and is formed by sintering a silver alloy paste which is composed of a silver alloy which is soluble in the melted fuse element 34 and glass frit is not added, and the pattern electrode 32 is formed on the upper and lower surfaces of the substrate. It has a silver alloy half through hole 37 for electrical connection. Although not particularly shown, the predetermined surface of the resistance heating element 36 of the second embodiment is glass overglaze.

In the protective elements with bypass electrodes of Examples 1 and 2, the wiring means for electrically connecting the pattern electrodes on the upper and lower surfaces of the insulating substrate was replaced with a half through hole, a conductor through hole penetrating the substrate, or a flat surface. You may change to the surface wiring by an electrode pattern.

The protection element with a bypass electrode according to the present invention can be mounted on a circuit board to be protected together with other surface mounting components, and can be collectively soldered and mounted by a reflow method or the like to be used as a protection device for a secondary battery such as a battery pack.

10, 20, 30... Protective element with bypass electrode,
11, 21, 31... Insulating substrate,
12, 22, 32... Pattern electrodes,
13, 23, 33... Bypass electrode,
14, 24, 34... Fuse element,
15, 25, 35... Lid,
26, 36... Resistance heating element,
17, 27, 37... Half through hole.

Claims (3)

An insulating substrate, a plurality of pattern electrodes provided on the insulating substrate, a bypass electrode made of a low resistance material that electrically connects the predetermined pattern electrodes, and a bridge between the predetermined pattern electrodes and the bypass electrode. And a fuse element provided in proximity to the fuse element, the bypass electrode is provided on the insulating substrate, has a higher melting temperature than the fuse element, and sinters a meltable metal paste to the melted fuse element. A protection element with a bypass electrode , comprising a formed metal material , wherein the metal paste is a glass frit content not added or less than 2% by mass . The protection element with a bypass electrode according to claim 1, further comprising a resistance heating element provided on one surface of the insulating substrate. The bypass electrode protection according to claim 1 or 2, wherein the bypass electrode is made of at least one soluble metal material selected from the group consisting of copper, silver, copper alloys, and silver alloys. element.

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