JP6912314B2 - Protective element - Google Patents

Description

The present invention relates to a protective element for electrical / electronic equipment.

In recent years, with the rapid spread of small electronic devices such as mobile devices, small and thin protective elements mounted on the protection circuit of the power supply to be mounted have been used. For the protection circuit of the secondary battery pack, for example, a protection element of 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 the overcurrent of the protected device, or respond to abnormal overheating of the ambient temperature and operate the fuse under predetermined conditions to cut off the electric circuit. There is a non-resettable protective element. In order to ensure the safety of the equipment, the protection element heats the resistance element by the signal current when the protection circuit detects an abnormality that occurs in the equipment, and the heat generation blows the fuse element made of a fusible alloy material. The fuse element is blown by an overcurrent to cut off the circuit.

For example, as described in Patent Document 1 and the like, a protective element using a low melting point metal material that melts at a soldering temperature and a fuse element material formed by laminating a soluble metal structural material on a low melting point metal material is provided. be. The fuse element material of this protective element is to support and hold a low melting point metal material that has been liquid-phased by soldering work to a solid-phase metal structural material at that temperature so that it will not melt for a certain period of time. The shape of the fuse element is maintained at least during the soldering operation to prevent the fuse element material from malfunctioning during reflow soldering. 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 which is the medium by the heat of soldering and becomes thin. Therefore, 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 can operate without hindering fusing.

JP-A-2015-079608

As the fuse element used for the protection element, it is preferable to use a material having a low electric resistance value as much as possible from the viewpoint of coping with high current and standby energy loss of the rechargeable battery. However, the types of easily fused gold that can be applied to the fuse element of the protective element are limited, and it is not always possible to select one with a low electrical resistance value. In reality, in order to ensure practicality such as operating performance, it is often necessary to use a fuse element having a relatively large electric resistance value.

The present invention has been proposed to solve the above-mentioned problems and further improve the circuit protection element, and is a new configuration capable of reducing the internal resistance value of the circuit protection element without being influenced by the intrinsic resistance value of the fuse element material. It is an object of the present invention to provide a protective element provided with.

According to the present invention, an insulating substrate, a plurality of electrodes provided on the insulating substrate, a low melting point metal electrode filler filled between the predetermined electrodes, and electrodes bridged between the predetermined electrodes. A protective element with an electrode filler is provided with a fuse element covering the upper part of the filler, and the electrode filler is made of a metal material whose melting temperature is equal to or lower than the liquidus temperature of the fuse element. Provided. The protective element of the present invention may be provided with a heat generating element on an insulating substrate, if necessary. The electrode filler of the present invention reduces the internal resistance value by being provided so as to fill the gap between the electrodes for bridging the fuse element. The gap between the electrodes is a groove-shaped portion formed of the opposite electrode ends and the insulating substrate surface between them. As the electrode filler, any metal material may be used as long as the melting temperature is equal to or lower than that of the fuse element, and a material having an electric resistance smaller than that of the fuse element is more preferable. An example is tin or tin-based soldering material.

The electrode filler of the present invention fills the gap (hollow space) between the electrodes in which the fuse element is bridged, thereby expanding the cross-sectional area of the current-carrying path of the fuse element and reducing the internal resistance of the protective element. Let me. Since the electrode filler is made of a metal material having a temperature equal to or lower than the melting temperature of the fuse element, it does not interfere with the blowing operation of the fuse element. Moreover, as the electrode filler, easily fused gold such as a solder material can be used as it is, and it is not necessary to use a precious metal material such as a sterling silver material or a silver-based alloy (high silver content alloy), which is economical.

The perspective view which disassembled the component member of the protection element 10 with an electrode filler which concerns on this invention is shown. The protective element 20 with an electrode filler according to the present invention, (a) shows a plan view in which a lid is cut along the dd line of (b), and (b) is a DD of (a). A cross-sectional view cut along the line is shown, and (c) shows a bottom view thereof. A cross-sectional view of a main part of the protective element 20 with an electrode filler according to the present invention is shown. In FIG. 3, the lid body, the electrodes on the back surface of the insulating substrate, and the heat generating element are omitted.

As shown in FIG. 1, the protective element 10 with an electrode filler according to the present invention is filled between an insulating substrate 11, a plurality of electrodes 12 provided on the insulating substrate 11, and a predetermined electrode among the electrodes 12. An electrode filler 13 made of a low melting point metal, a fuse element 14 that bridges between the predetermined electrodes and covers the upper part of the electrode filler 13, and an operating flux (not shown) applied to the surface of the fuse element 14. The electrode filler 13 is provided with a lid 15 that covers the upper part of the fuse element 14 together with the operating flux, and the electrode filler 13 is characterized in that the melting temperature thereof is made of a metal material whose melting temperature is equal to or lower than the liquidus temperature of the fuse element 14. do. The insulating substrate 11 may be of any material and composition as long as it is an insulating material, and for example, plastic, glass, glass ceramic, ceramic and the like are suitable. The electrode 12 provided on the insulating substrate 11 may be of any material and composition as long as it is a conductive material, and for example, copper, silver, a copper alloy, and a silver alloy are suitable. The electrode filler 13 may be of any material and composition as long as it can be filled and formed in the electrode gap of the electrode 12 and the melting temperature is equal to or lower than that of the fuse element 14. For example, a tin-based alloy or tin. Metallic materials filled with solder paste consisting of −lead alloys, tin-copper alloys, tin-silver alloys, tin-silver-copper alloys, tin-based alloys, tin-lead alloys, tin-copper alloys, tin-silver alloys, Filled and formed by a metal material filled with a solder ball made of a tin-silver-copper alloy, a tin-based alloy, a tin-lead alloy, a tin-copper alloy, a tin-silver alloy, and a partial plating made of a tin-silver-copper alloy. Metal materials can be used. The electrode filler 13 can be integrally integrated with the fuse element 14 as the protective element 10 with the electrode filler is mounted on the surface. When the fuse element 14 is blown, the fuse element 14 is spherically formed together with the liquid-phased fuse element 14, so that the electrode filler 13 does not interfere with the blowing operation. The fuse element 14 may be of any material and composition as long as it is an easily meltable metal material. For example, tin-based alloy, tin-lead alloy, tin-copper alloy, tin-silver alloy, tin-silver-copper Alloys and the like can be preferably used. Further, the fuse element 14 may use a metal material having a single composition or may be used as a composite material by combining a plurality of metal materials having different compositions. The protective element 10 with an electrode filler of the present invention may be provided with a heat generating element on one side of the insulating substrate 11 as needed. The heat generating element is coated with an insulating coating as needed. When the heat generating element is not provided, the central electrode of the electrodes 12 connected to the fuse element 14 may be omitted. The shape and material of the lid 15 are not limited as long as they can cover the upper parts of the insulating substrate 11 and the fuse element 14 to secure a desired cavity space. For example, a dome-shaped resin film cover, a plastic lid, a ceramic lid, or the like can be preferably used for the lid body 15.

As shown in FIGS. 2 and 3, the protective element 20 with an electrode filler according to the first embodiment of the present invention includes an alumina-ceramic insulating substrate 21 and a plurality of silver alloy electrodes 22 provided on the insulating substrate 21. A resistance heating element 26 electrically connected to the electrode 22 and provided on the lower surface of the insulating substrate 21, and an electrode filler 23 of a 96.5 Sn-3Ag-0.5Cu alloy filled between the predetermined electrodes of the electrodes 22. A fuse element 24 made of a clad material of 92Pb-Sn alloy 24-1 and 99.3Sn-0.7Cu alloy 24-2, which bridges between the predetermined electrodes and covers the upper part of the electrode filler 23. The electrode filler 23 includes an operating flux (not shown) applied to the surface of the fuse element 24 and a lid 25 made of a liquid crystal polymer that covers the upper part of the fuse element 24 together with the operating flux, and the melting temperature of the electrode filler 23 is high. It is characterized in that it is made of a metal material having a temperature equal to or lower than the liquidus temperature of the fuse element 24. The electrode 22 has a silver alloy half through hole that electrically connects the electrodes 22 on the upper and lower surfaces of the substrate. The surface of the resistance heating element 26 of Example 1 is overglaze with insulating glass. Here, for the purpose of comparison with the protective element 20 with the electrode filler of the first embodiment, a protective element of the comparative example manufactured by using the same parts and members as the first embodiment without providing the electrode filler is prepared. The internal resistance values of both were measured. The internal resistance value of the protective element 20 with the electrode filler in Example 1 was 0.45 mΩ (corresponding to the rated current of 25 A), whereas the internal resistance value of the protective element of the comparative example without the electrode filler was 0.45 mΩ (corresponding to the rated current 25 A). It was 0.60 mΩ (corresponding to a rated current of 20 A). It can be seen that the present invention reduces the internal resistance of the protective element and thus improves the rated current value.

In the protective element with an electrode filler of the present invention, voids may be generated at the interface between the electrode filler and the insulating substrate due to heating, but this is not a problem because the conduction path is maintained.

The protective element with an electrode filler of the present invention can be mounted on a protected circuit board together with other surface mount components, and can be collectively soldered and mounted by a reflow method or the like, and can be used as a protective device for a secondary battery such as a battery pack.

10, 20 ... Protective element with electrode filler,
11, 21 ... Insulated substrate,
12, 22 ... Electrodes,
13, 23 ... Electrode filler,
14, 24 ... Fuse element,
15, 25 ... lid,
26 ... Heat generating element.

Claims (5)

An insulating substrate provided with heat generating elements on one side, filling the plurality of electrodes provided on the insulating substrate, between the opposing electrode end between them insulation consists substrate surface a groove-like gap of predetermined electrodes of the electrode The electrode filler is provided with a low melting point metal electrode filler and a fuse element made of an easily meltable metal that bridges between the predetermined electrodes and covers the upper part of the electrode filler. The electrode filler has a melting temperature of the above. A protective element with an electrode filler made of a metal material that is below the liquidus temperature of the fuse element. The protective element with an electrode filler according to claim 1 , wherein the electrode filler is selected from the group of tin-based alloys, tin-lead alloys, tin-copper alloys, tin-silver alloys, and tin-silver-copper alloys. The fuse element includes the electrode filler according to claim 1 or 2 , which is selected from the group of tin-based alloys, tin-lead alloys, tin-copper alloys, tin-silver alloys, and tin-silver-copper alloys. Protective element. The protective element with an electrode filler according to claim 3 , wherein the fuse element is made of a composite material in which a plurality of metal materials having different compositions are combined. A groove-like gap composed of an insulating substrate provided with a heat generating element on one surface, a plurality of electrodes provided on the insulating substrate, opposite electrode ends of predetermined electrodes among these electrodes, and an insulating substrate surface between them was filled. The electrode filler is provided with an electrode filler of a low melting point metal and a fuse element of a flexible metal material that bridges between the predetermined electrodes and covers the upper part of the electrode filler. The electrode filler has a melting temperature of the fuse. A method for manufacturing a protective element with an electrode filler, which is made of a metal material having a liquidus temperature or lower of the element.
The electrode filler is filled with a solder paste, filled with a solder ball, or filled with a partial plating, or a protection with an electrode filler manufactured by a method. Method of manufacturing the element.

Images