JP4573865B2 - Protective device using temperature fuse - Google Patents

Description

The present invention provides a protection circuit in which a lead member is disposed on one surface of a ceramic substrate, a lead member is disposed on the other surface, a temperature fuse protection component suitable for thinning and downsizing, and a control element for detecting an abnormal signal on the mounting substrate. protection apparatus comprising, in particular, lead-Li ceramic substrate - on the protection device using a thermal fuse that allows downsizing equipped with a protection component via the de member mounted on the substrate for the protection circuit.

Conventionally, temperature fuses are known to be operated by excessive heat generated by the overcurrent of the protected device, as well as temperature fuses that operate by detecting an abnormal signal generated in the device and generating resistance by this signal. Yes. For example, high-density energy lithium-ion secondary batteries with excellent storage characteristics and leakage resistance are used as the main power source for electronic devices that are portable information terminal devices, but thermal fuses are used as protective components to ensure their safety. Used as. In general, in secondary batteries, it is desirable to provide a reset circuit and a non-reset type protection circuit to prevent overcharge and overdischarge. When the battery voltage exceeds a preset voltage, the charging current is cut off. a return-type protection circuit, patent that the protection circuit constituting the high protection device safety with a non-return type protection circuit for blowing the thermal fuse when the battery voltage does not operate for some reason abnormally elevated literature 1 is disclosed .
The temperature fuse used in the non-recoverable protection circuit is a resistance built-in temperature composed of two fusible elements connected in series between the charger and the battery and the resistance of a heating element that is thermally coupled to these elements. The fuse is a fuse that detects the battery voltage and operates in response to an ON signal of a voltage detection circuit that outputs an ON signal when the battery voltage exceeds a set value.

On the other hand, the present inventor, entitled “Development of Resistor Built-in Thermal Fuse” in p93-p96 of Non-Patent Document 1, describes the development point and mounting method of this type of thermal fuse, Describe the problem. FIG. 8 shows a side view of a part of the structure of a resistance built-in thermal fuse 1 conventionally used in this type of protection circuit. The ceramic substrate 2 and a low melting point alloy mounted on the surface side of the substrate are shown. The fusible element 3 and a ceramic cap 5 covering the fusible element 3, a lead 4 for soldering to the electrode to which the fusible element is welded, and a resistor 6 formed on the back side of the substrate 2. . This built-in resistor temperature fuse is incorporated as a non-recoverable protection circuit for the secondary battery described above, and when an abnormality such as overcharge is detected, the resistor 6 thermally coupled to the fusible element 3 is energized. The resistance is heated to forcibly melt the fusible element and break the circuit. Usually, the protection circuit is configured to be mounted on a printed board together with a control element such as a dedicated control IC including a switching element such as a MOSFET for controlling charging and discharging. For example, a resistance built-in thermal fuse is stacked on the upper side of the switching element of the control circuit component or arranged side by side on the lateral side.
JP-A-10-56742 NEC Technical Report Vol. 53No. 10

  As described above, the conventional resistance built-in thermal fuse has mounted a single element or two fusible elements together with a lead on one surface of an insulating substrate. Requires a large space for installation. This has resulted in inconvenience when applied to portable information devices and the like that require a reduction in size and thickness, and has become a problem in assembly. In addition to the thermal fuse, it has been desired to realize a thin and small size as much as possible in order to make it compact not only for the devices after incorporation. In addition, in order to increase the temperature detection sensitivity of the thermal fuse and operate it with high accuracy, it is desirable to have a mounting arrangement that is in close proximity to a switching element that may be abnormally overheated. It has been desired to present an improved mounting structure on a circuit component.

Therefore, the present invention has been proposed in view of the fact that the above-described conventional unsolved thermal fuse main body structure is enlarged and the mounting space is increased. It is an object of the present invention to provide a thermal fuse and a protection device using the same .

An object of the present invention is to provide a thermal fuse reduced in size by arranging a fuse element on one surface of an insulating substrate and a lead member for lead-out on the other surface, and to provide a protection circuit with an improved mounting method. to built more is achieved to provide a protective device using a new and improved temperature-use more effective use can be achieved even more space surface causes efficiently operated in performance.

As means for achieving the above-mentioned object, the present invention provides a ceramic insulating substrate having a pattern electrode and a through hole, a fuse element disposed on the surface side of the insulating substrate, and a back surface side. There is provided a thermal fuse comprising a lead member arranged and having a fuse element and a lead member respectively connected to a predetermined pattern electrode . Fuse element will be sealed by the fusible insulation cap of the low melting alloy, the fuse element and the thermal coupling to the heater element is disposed on the insulating substrate, the low melting point alloy fusible operation temperature the same or different for fusing Disclosed is a thermal fuse, which can be composed of a plurality of parts set to a temperature, and is fused by heat generated by a heating element. Preferably, the heating element is a resistor arranged on the back side of the insulating substrate or in the through hole, and the lead member is a temperature fuse in which a solder-plated rectangular copper wire is bonded to a predetermined pattern electrode and fixed. It is a protection device using That is, a temperature at which a fuse element of a low melting point alloy fusible body is sealed on one side of a ceramic substrate with an insulating cap of approximately the same size as the ceramic substrate, and a lead member and a resistor heating element are arranged on the other side A non-returnable protection device in which a fuse protection component and a protection circuit mounted with a control element for detecting an abnormal signal on the mounting substrate are combined with the mounting substrate of the protection circuit via a lead member of the protection component, Lead members are solder-connected to pattern electrodes formed on both surfaces of the ceramic substrate and interconnected by conductive through holes, and the heating element is a thin film resistor provided in a thermally coupled state with the fuse element. Provides a protective device using a thermal fuse, wherein the thin film resistor is energized when the protective circuit detects an abnormal signal. That. Here, the protection circuit includes two control elements mounted in parallel on the mounting substrate, and the protection device using a thermal fuse is combined so that the fuse element is disposed between the control elements Is disclosed.

  According to another aspect of the present invention, in a non-returnable protective device mounting structure using a temperature fuse, a fuse disposed on the surface side of an insulating substrate having a pattern electrode and a through hole. A thermal fuse having a lead element disposed on the back surface side and a protection circuit having a control element for generating an abnormal signal, and the fuse element on the surface side of the insulating substrate is mounted in a gap near the element A protection device using is provided. Here, at least two control elements are used, and the thermal fuse includes a fuse element in which a fusible element of a low melting point alloy is sealed with an insulating cap, and a heating element mounted on an insulating substrate in a thermally coupled state with the fuse element. In this non-return type protective device, the insulating cap of the fuse element is fitted in the gap between the two control elements. Specifically, the protection circuit is applied to a charge / discharge control circuit for a battery pack including two control elements, and this control circuit detects an abnormal signal and causes resistance heating in the heating element. A protective device using a temperature fuse is disclosed.

The temperature fuse used in the protective device of the present invention exerts a very remarkable effect on the miniaturization, and is advantageous not only for the protective component but also for the miniaturization and compactness of the protective device to be mounted. The temperature fuse - When showing the external dimensions (mm) and the like by comparing's protection components and their traditional products and traditional market product is shown in Table 1. Therefore, as a protective component, the size and area of the insulating substrate are greatly different from those of the conventional product, and the manufacturing economical effect is exhibited by the reduction of the amount of insulating material used and the processing of the pattern electrode.

The temperature fuse used in the protective device of the present invention is greatly reduced in outer dimensions, particularly in the occupied area, as compared with the conventional product. This is based on the fact that the fuse element and the lead member on the insulating substrate are divided on both sides, thereby reducing the insulating substrate to be used by about 30%. In addition, by applying a cap type to the sealing structure of the fuse element, the insulation structure on the surface side is accurately regulated, and mounting in the air gaps of the protective circuit parts is facilitated during mounting, thereby protecting The device itself can be made compact. As described above, the temperature fuse used in the protective device of the present invention is useful for practical use by downsizing and compacting, and has an effect of increasing industrial value.

In the present invention, a fuse element of a low-melting-point alloy fusible body is sealed on one surface of a ceramic substrate with an insulating cap having a cover covering area that is substantially the same as or slightly smaller than that of the ceramic substrate, and a lead member and a resistor on the other surface. A thermal fuse provided with a body heating element is used as a protective component. On the other hand, a protection circuit having a control element for detecting an abnormal signal is prepared on the mounting printed board. This protection circuit is combined with a protection circuit mounting board via a lead member of a protection component to form a non-returnable protection device. Here, the lead member is solder-connected to the pattern electrode formed on both surfaces of the ceramic substrate and interconnected by the conductive through hole, and the heating element is formed of a thin film resistor provided in a thermally coupled state with the fuse element. When the protective circuit detects an abnormal signal, the thin film resistor is energized. The protective circuit includes two control elements mounted in parallel on the mounting printed board, and is assembled and combined so that a fuse element is disposed between the control elements. That is, a ceramic substrate having a plurality of through-holes, a plurality of electrodes connected to each other on both sides of the substrate via the through-holes, and a low melting point alloy fusible body mounted on one side of the substrate A fuse element sealed with a ceramic cap, a lead member mounted on the other surface of the substrate, and a heating element disposed on the ceramic substrate so as to be thermally coupled to the fuse element, the fuse element on the ceramic substrate a temperature fuse and compact by separating the arrangement surface of the lead member - a protective component's, coverage for sealing the insulating cap is placed on one surface of the ceramic substrate pattern - emission electrode and a low melting alloy The covering area including the fusible body is made smaller than the area of the entire ceramic substrate, and the lead member is made thin using a flat copper wire. Masui.

Another embodiment according to the present invention is a charge / discharge control circuit for a battery pack in which the protection device uses a thermal fuse, and the control circuit detects an abnormality and energizes a signal to the heating element to cause resistance heating. This is a non-recoverable protection circuit that melts the fusible body of the thermal fuse. The temperature fuse used here includes a ceramic substrate having a plurality of pattern electrodes on both sides and a conductive through hole connecting the pattern electrodes on both sides, and the surface of the ceramic substrate. A fuse element composed of a ceramic cap that covers and seals a fusible body of a low-melting-point alloy that is welded to a pattern electrode disposed on the side, a thin film resistor of a heating element formed on the ceramic substrate, and a back surface side pattern of the ceramic substrate A plurality of lead members soldered to the lead electrodes;

Embodiments relating to a thermal fuse protection component used in the protection device of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, FIG. 2, or FIG. 3, the temperature fuse 10 of the present invention is disposed on the ceramic substrate 12 made of alumina, the fuse element 13 disposed on one surface thereof, and the other surface. Lead-out lead members 14a, 14b, and 14c. The fuse element 13 is formed by sealing a fusible element of a low melting point alloy with a ceramic cap 15. In addition, the ceramic substrate 12 has a resistive heating element 16 disposed in thermal coupling with the fuse element 13. Here, each component is formed and processed so as to be as small and thin as possible. Specifically, the resistance of the heating element 16 is a thin film resistance on the back surface or a resistor mounted on the through holes e, f, and g. The lead members 14a, 14b, and 14c are used by soldering a flat copper wire to a pattern electrode. The ceramic substrate 12 and the cap 15 are formed into a predetermined shape at the green sheet stage before the sintering process, and the edges of the cap and the through holes e, f, and g of the substrate are processed. Processing is performed. A predetermined pattern electrode is formed by heating on the sintered ceramic substrate 12, and the thin film resistor of the heating element 16 is similarly formed in this step as needed. As for the resistance of the heat generating element 16, a resistor may be soldered to a predetermined pattern electrode, and through holes e, f, and g can be used at the arrangement place. The ceramic substrate 12 may be an insulating material other than alumina as long as it maintains good insulating properties, and pattern electrodes are formed in a predetermined shape on each surface of the insulating substrate. At a predetermined position, a conductive through hole is formed so that the pattern electrodes on both sides are electrically connected through three through holes e, f, and g.

4 and 5, three pattern electrodes 21, 22, and 23 are formed on the surface of the ceramic substrate 12 so as to be connected to the three through holes 31, 32, and 33, respectively. In addition to the three pattern electrodes 21, 22, 23 connected to the three through holes 31, 32, 33, an independent electrode pattern 27 is formed on the back surface. The fusible element 17 of a low melting point alloy is bridged to the pattern electrodes 21, 22, and 23 on the surface side of the substrate to be welded to the three pattern electrodes 21, 22, and 23, A dual type thermal fuse element having the second fusible body 19 is formed. The fusible element 17 welded to each pattern electrode is sealed and sealed with an insulating ceramic cap 15 that is slightly smaller than the insulating ceramic substrate 12 including the three pattern electrodes 21 to 23 after the flux is deposited. Covered. The fuse element 13 may be a single type fusible element, and in the case of a dual type fusible element, the operating temperatures of the respective fusible elements can be made the same or different. For dual types with different operating temperatures, it is desirable that the temperature difference be within the range of variations in operating temperature.

On the other hand, in FIG. 5 which shows the back surface side of the ceramic substrate 12, two pattern electrodes 26 and 27 are formed in the central portion, and the heating element 16 is disposed between them. The pattern electrode 26 and the pattern electrodes 24 and 25 are connected to the surface side pattern electrodes 23, 21, and 22 through the through holes 32, 31 and 33, respectively. Three lead member 14 disposed on the back side, the flat rectangular copper wire solder plating is employed, sul - ho - patterns independent of the pattern electrodes 24 and 25 connected to the surface side by the interposition of Le 31-33 Each electrode 27 is fixed by soldering. The thermal fuse has a rated DC of 32 V, 10 A, an operating temperature of 135 ° C., and a heating resistance of 50Ω, and the external dimensions of the finished product are extremely small, with the ceramic substrate body being 4 mm long, 5 mm wide, and 1.5 mm thick. The ceramic substrate 12 set in a square shape is an alumina substrate having a thickness of 0.4 mm, and the required capacity of the alumina ceramic is greatly reduced by downsizing, and an economical merit in terms of cost can be obtained. In the case of forming the film by screen printing, since it is a small substrate, it is possible to obtain an economical effect in manufacturing such that a large number of printing processes can be simultaneously performed by one printing. Furthermore, since the lead member 14 uses a flat Sn-Ag plated copper wire having a width of 0.7 to 1.0 mm and a thickness of 0.2 to 0.4 mm, the lead member 14 contributes to a reduction in the thickness of the main body and is made thinner. Useful.

6 and 7 are a partial plan view and a side view showing the non-returnable protective device according to the present invention. The temperature fuse 10 of the protective component used in the present invention relates to a structure for mounting a secondary battery on an overcharge protection circuit, and the ceramic cap side between active elements 36 and 37 such as MOSFETs mounted on a printed circuit board 35 for mounting. It is attached so as to be fitted with the face down. Since the fuse element of the thermal fuse 10 is sealed with a ceramic cap on one surface of the ceramic substrate as described above, this part can be mounted close to the heat sensitive part of the active element. In addition, since the temperature fuse is mounted using the gap space between the circuit component elements, the portable information communication device using this kind of protection circuit is compact and advantageous for reduction in size and thickness. Therefore, the separation arrangement of the lead member for lead and the fuse element with respect to the insulating substrate, which is the focus of the present invention, realizes the miniaturization of components and effectively uses the space between the protection circuit control elements by the mounting method. Helps to make the whole compact.

It is a front view of the resistance built-in temperature fuse used for the protection apparatus of this invention . FIG. 2 is a side view showing a partial cross section of the resistor built-in temperature fuse of FIG. 1 . It is a rear view of the temperature fuse with a built- in resistor of FIG. It is a top view of the ceramic substrate of the protection component used for the protection apparatus of this invention . FIG. 5 is a rear view of the ceramic substrate of the protective component of FIG. 4 . It is a top view which shows the mounting structure which united the protection circuit and the protection apparatus with the protection apparatus which concerns on this invention . It is a side view which similarly shows the mounting structure of the protection apparatus of FIG. It is a side view which shows the partial cross section of the mounting state of the conventional resistance built-in temperature fuse .

Explanation of symbols

10 ... Thermal fuse with built-in resistor (protection part)
12 ... Ceramic substrate (insulating substrate)
13 ... Fuse element 14a, 14b, 14c ... Lead member 15 ... Ceramic cap (insulating cap)
16 ... resistor (heating element)
17 ... soluble element (low melting point alloy soluble element)
21, 22, 23, 24, 25 , 26 , 27 ... pattern electrodes e, f, g, 31 , 32 , 33 ... through holes
35 ... Printed circuit board (mounting board)
36, 37 ... Active elements (control elements)

Claims (2)

A ceramic substrate, a low melting point alloy fusible fuse element disposed on one surface of the ceramic substrate, an insulating cap of substantially the same size as the ceramic substrate on which the fuse element is sealed, and the other surface of the ceramic substrate A thermal fuse protection component comprising a lead member and a resistor heating element disposed on the substrate, and a protection circuit comprising a mounting substrate and a control element capable of detecting an abnormal signal mounted on the mounting substrate, the lead member and the A non-returnable protection device in which the protection component and the protection circuit are combined with the insulating substrate side of the ceramic substrate facing the mounting substrate through the mounting substrate , wherein the lead member is formed on both surfaces of the ceramic substrate. are soldered to the interconnect pattern electrodes in the conducting through-hole is formed on said heat generating element is the human A protective device using a thermal fuse, wherein the thin-film resistor is provided in a state of being thermally coupled to a light-emitting element, and the thin-film resistor is energized when the protective circuit detects an abnormal signal. .   2. The thermal fuse according to claim 1, wherein the protection circuit includes two control elements mounted side by side on the mounting substrate, and the fuse element is combined so that the fuse element is disposed between the control elements. The protective device used.

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