JP4301474B2 - Protective element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a protective element, and more specifically, a resistor having a temperature fuse having a fusible alloy that melts at a specific temperature, and a resistor that forcibly blows the fusible alloy and the fusible alloy by energization heating. The present invention relates to a protective element such as a fuse with a body.
[0002]
[Prior art]
As a protection element that protects electronic devices and the like from overheating damage, a thermal fuse that operates at a specific temperature and interrupts a circuit is used. This type of temperature fuse uses an insulating temperature-sensitive pellet that melts at a specific temperature as a temperature-sensitive material, and a temperature-sensitive pellet type that separates the movable contact from the fixed contact by extension of the compression spring when the temperature-sensitive pellet melts (A) and a fusible alloy type (b) that uses a fusible alloy that melts at a specific temperature as a temperature sensitive material, energizes the fusible alloy, and interrupts the circuit by melting the fusible alloy. is there. There is also a protective element (c) called a fuse with a resistor that includes a fusible alloy and a resistor and forcibly blows the fusible alloy by energization heating of the resistor.
Since the present invention relates to improvement of the b-type and c-type protection elements, such a type will be described below. The b-type protective element is disclosed, for example, in Japanese Utility Model Laid-Open No. 57-141346. A c-type protection element is disclosed in, for example, Japanese Utility Model Laid-Open No. 58-52848. Some of the b-type and c-type protection elements have a thin structure.
[0003]
First, the thermal fuse as the b-type protection element will be described with reference to FIGS. 23 and 24. FIG.
FIG. 23 is a longitudinal sectional view of a conventional thermal fuse D having a thin structure, and FIG. 24 is a plan view of the thermal fuse D in which the insulating cap and the flux are removed so that the internal structure can be seen, that is, before the flux application. It is.
23 and 24, reference numeral 81 denotes a rectangular insulating substrate made of ceramic such as alumina, which is formed by applying and baking a conductive paste such as a silver paste or a silver-palladium paste at both ends in the longitudinal direction of one surface thereof. A pair of electrodes 82 and 83 is provided. Leads 84 and 85 are fixedly connected to the outer ends of the pair of electrodes 82 and 83 by solders 86 and 87, respectively. A fusible alloy 88 that melts at a specific temperature is bridged between the inner ends of the electrodes 82 and 83, and the surface of the low melting point alloy 88 is covered with a flux 89. The fusible alloy 88 and the flux 89 are sealed from above the sealing resin 90.
[0004]
Next, a method for using the thermal fuse D will be described.
The thermal fuse D is connected in series to an electronic device via its leads 84 and 85. Then, if the ambient temperature is within the normal range, the electronic device is energized via the lead 84-electrode 82-soluble alloy 88-electrode 83-lead 85. When the ambient temperature rises due to an abnormality of the electronic equipment and the like and becomes close to the melting point of the fusible alloy 88, the flux 89 softens and melts and activates the surface of the fusible alloy 88. Ready state. When the ambient temperature further rises and reaches the melting point of the fusible alloy 88, the fusible alloy 88 melts and is attracted to the electrodes 82 and 83 by its surface tension, and is melted from the central portion to be spheroidized (88a, 88b). ) And power is cut off. (The state after operation is not shown)
As a result, even when the ambient temperature is lowered, the fusible alloys 88a and 88b attracted to the electrodes 82 and 83 and spheroidized do not return to the original state, and thus function as a so-called non-recoverable protection element.
[0005]
[Problems to be solved by the invention]
In the thermal fuse D, since the leads 84 and 85 are connected via the electrode 82-soluble alloy 88-electrode 83, if the resistance value of the electrodes 82, 83 is large, the internal resistance of the thermal fuse D is also increased. Therefore, at a high current, the fusible alloy may be mismelted by self-heating, and the voltage drop to the electronic device may decrease due to the voltage drop. On the other hand, when the electrodes 82 and 83 are formed thick, the amount of expensive electrode paste used increases, and there is a problem that cost increases cannot be avoided.
[0006]
Although not intended to reduce the internal resistance of the thermal fuse, when the meltable alloy 88 is melted, if the melted melted alloy 88 is weakly attracted to the electrodes 82 and 83, the melted soluble alloy 88 is weak. In order to solve the problem that the fusible alloy 88 may not be cut in a severe case, the protection element E as shown in FIG. 25 and FIG. No. 4-36025).
Hereinafter, the protection element E will be described. 25 and 26, reference numeral 91 denotes an insulating substrate, and electrodes 92 and 93 are formed on the surface of the insulating substrate, and the tips of the electrodes 92 and 93 are close to the inner ends of the electrodes 92 and 93. Leads 94 and 95 are fixed by solder 96 and 97. A fusible alloy 98 that melts at a specific temperature is fixed between the electrodes 92 and 93 so that both ends thereof are in contact with the tips of the leads 94 and 95. A flux 99 is deposited on the fusible alloy 98, and a sealing resin 100 is covered and sealed on the flux 99.
According to such a protective element E, when the fusible alloy 98 is melted, the melted fusible alloy 98 is attracted not only by the electrodes 92 and 93 but also by the tip portions of the leads 94 and 95. The alloy 98 acts to surely melt from its central portion.
[0007]
However, in this thermal fuse E, not only the technical idea of cost reduction by reducing the amount of conductive paste used for forming the electrodes 92 and 93 is recognized, but also the leads 94 and 95 on the electrodes 92 and 93. Is fixed by extending the tip of the electrode 92 and 93 to the vicinity of the inner ends of the electrodes 92 and 93, and the fusible alloy 98 is brought into contact with the inner ends of the leads 94 and 95 between the electrodes 92 and 93. Such fixing is difficult due to the dimensional accuracy of the fusible alloy 98 and the positioning accuracy when the fusible alloy 98 is fixed.
If both ends of the fusible alloy 98 are not in contact with the inner ends of the leads 94 and 95, the expected effect cannot be obtained. Further, when only one end of the fusible alloy 98 is in contact with the inner end of either one of the leads 94 and 95, the attracting force of the melted fusible alloy 98 becomes unbalanced, and the fusing is performed. There is a problem that not only the characteristics are likely to vary but also the fusing characteristics are deteriorated as compared with the case where only the electrodes 92 and 93 are bridged.
[0008]
Such a problem has not only a so-called thermal fuse having a soluble alloy 98 as described above, but also a soluble alloy and a resistor, and is caused by energization heat generation to the resistor. This also occurs in a protective element called a fuse with resistance, which forcibly melts a fusible alloy.
[0009]
Accordingly, the present invention provides a protection element such as a temperature fuse or a resistance fuse in which the fusible alloy is surely and easily blown when the fusible alloy melts in the protection element referred to as the above-described temperature fuse or resistance temperature fuse. The purpose is to provide.
[0010]
[Means for Solving the Problems]
  According to the present inventionAn insulating substrate, electrodes formed on the insulating substrate, leads fixed on the electrodes, a fusible alloy bridged on the leads, and the fusible alloy Cover the flux and cover the fluxInsulation capA protective element having an insulating sealing materialWill be provided. According to such a protective element, the lead is fixed on the electrode, and the fusible alloy is fixedly connected to the lead. Therefore, the resistance value of the electrode can be ignored, and therefore, the electrode can be formed thin. The cost can be reduced by reducing the amount of conductive paste used. Further, even if the length of the fusible alloy varies slightly or the position where the fusible alloy adheres slightly, the fusible alloy can be fixed and connected to the lead easily and reliably.The insulating cap is fixed and sealed to the insulating substrate with a sealing resin, so that when the flux and the fusible alloy are melted, a space where they can flow is secured, and the fusible alloy responds accurately to the ambient temperature. Fusing. Furthermore, it is preferable that the lead has a shape covering almost the entire surface of the electrode, whereby the area of the lead is large, and the fusible alloy can be securely connected to the lead.
[0013]
Of the present inventionClaim 1The invention described in the above is a protective element in which the insulating cap has a top plate portion, a falling portion, and a protruding portion that protrudes corresponding to the thickness of the lead at a portion corresponding to the space between the leads. is there. According to such a protective element, when the flux and the fusible alloy are melted as described above, a space in which they can flow can be secured, and the fusible alloy not only blows out in response to the ambient temperature accurately, but also the protrusions. Due to the presence of the insulating substrate, the insulating substrate and the insulating cap can be fixedly sealed with the same thickness of sealing resin.
[0014]
Of the present inventionModified exampleThe width dimension of the inner end of the lead is set smaller than the inner dimension in the short direction of the insulating cap, and the protrusions at both ends in the short direction of the insulating cap are the longitudinal direction of the insulating cap. It is formed over the entire length of the protective element. According to such a protective element, the projecting portions at both ends in the short direction of the insulating cap are formed over the entire length in the longitudinal direction of the insulating cap, thereby sealing the both ends in the short direction of the insulating cap and the insulating substrate. A stop part becomes a linear form and the thickness of sealing resin can be made uniform easily.
[0015]
Of the present inventionClaim 2In the described invention, the inner dimension in the short direction of the insulating cap is formed substantially the same as the width dimension in the short direction of the insulating substrate, and the total dimension of the falling portion and the protruding portion is the insulating substrate. , Electrode, lead, fusible alloy and flux are set equal to or higher than the total heightClaim 1It is a protection element of description. According to such a protective element, the insulating cap, the electrode, the fusible alloy, the entire flux, etc. can be covered with the insulating cap.Here, the insulating cap can support the insulating substrate at the stepped portion of the insulating cap by providing a stepped portion for supporting the insulating substrate in the middle portion on the inner surface side of the falling portion and / or the protruding portion, and the flux In addition, when the fusible alloy is melted, a space for these to flow can be secured easily and reliably.
[0017]
Of the present inventionAnother variationIs a protective element having an electrode for a resistor on the insulating substrate, a resistor that is bridged between the electrodes and that forcibly melts the soluble alloy by heat generated by energization, and an insulating film that covers the resistor It is. According to such a protective element, by supplying electricity to the resistor to generate heat, the fusible body can be forcibly blown regardless of the ambient temperature, and is different from the thermal fuse that blows in response to the ambient temperature. Is obtained. In addition, since the fusing temperature of the fusible body can be set regardless of the ambient temperature, the selection range of the melting temperature and alloy composition is expanded.Here, the electrode for the resistor, the resistor, and the insulating film are preferably provided on the side of the insulating substrate opposite to the side on which the soluble alloy is fixed, so that the protective element can be made compact.
[0019]
Of the present inventionYet another variationThe electrode for soluble alloy formed on one surface of the insulating substrate and the electrode for resistor formed on the other surface of the insulating substrate are formed in a through hole formed in the insulating substrate. Through the conductive layerConnectedIt is a protection element. According to such a protective element, the number of leads can be reduced by connecting the electrodes on both sides of the insulating substrate via the conductive layer formed on the inner surface of the through hole formed in the insulating substrate, Costs can be reduced by reducing the number of parts and connecting man-hours.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1
FIG. 1 is a longitudinal sectional view of a protective element A composed of a thin resistor-equipped fuse according to a first embodiment of the present invention. 2 is a plan view of the protective element A, FIG. 3 is a front view, FIG. 4 is a left side view, and FIG. 5 is a plan view with the insulating cap and flux removed. FIG. 1 is a longitudinal sectional view taken along line AA in FIG. 6 to 11 show a plan view or a bottom view of the insulating substrate in each manufacturing process of the protective element A, and FIG. 12 shows a bottom perspective view of the insulating cap.
[0021]
In the protection element A shown in FIGS. 1 to 12, reference numeral 1 denotes a rectangular insulating substrate made of alumina ceramic, glass ceramic or the like, which is decentered near the longitudinal ends of the surface and from the central axis as shown in FIG. It has through-holes 2 and 3 drilled on the same short side end side. As shown in FIG. 7, three electrodes 4, 5, 6 are formed on both ends of the surface of the insulating substrate 1 by applying and baking a conductive paste made of silver paste, silver-palladium paste or the like. Here, the electrode 4 is formed in an inverted L shape in a region avoiding the through hole 3, the electrode 5 is formed in an L shape in a region including the through hole 2, and the electrode 6 Is formed in a rectangular shape in a region including the through hole 3. Of these electrodes 4, 5, 6, the electrodes 4, 5 are electrodes for fusible alloys, which will be described later, and the electrode 6 is an electrode for relay to a resistor, which will be described later. In the step of forming these electrodes 4, 5, 6, a conductive layer is formed by applying and baking a conductive paste on the inner surfaces of the through holes 2, 3.
[0022]
As shown in FIG. 8, at both ends of the back surface of the insulating substrate 1, a conductive paste made of silver paste, silver-palladium paste or the like is applied and baked to form two resistors electrodes 7 and 8. Yes. One electrode 7 is formed in a region including the through hole 2, and the other electrode 8 is formed in a region including the through hole 3. The electrodes 7 and 8 are connected to the electrodes 5 and 6 on the surface of the insulating substrate 1 through conductive layers formed on the inner surfaces of the through holes 2 and 3 of the insulating substrate 1, respectively.
[0023]
As shown in FIG. 8, a resistor 9 is formed by applying and baking a resistor paste containing, for example, ruthenium oxide over the electrodes 7 and 8 on the back surface of the insulating substrate 1. As shown in FIG. 9, an insulating film 10 made of solder resist, glass or the like is formed so as to cover the electrodes 7, 8 and the resistor 9 on the back surface of the insulating substrate 1.
[0024]
As shown in FIG. 10, on the electrodes 4, 5, 6 on the surface of the insulating substrate 1, leads 11, 12, 13 having substantially the same shape and slightly smaller dimensions as the respective electrodes are solders 14, 15, 16 is connected. “Slightly small” here refers to the amount of fillet formation for the solders 14, 15, and 16. The tip of the lead 11 connected to the electrode 4 has an inverted L shape. The lead 12 connected to the electrode 5 has an L-shape and is connected so as to cover the through hole 2. Further, the lead 13 connected to the electrode 6 is straight and connected so as to cover the through hole 3. When the leads 11, 12, 13 are connected, the molten solders 15, 16 connecting the leads 11, 13 pass through the through holes 2, 3 and are formed on the back surface of the insulating substrate 1. Therefore, the connection resistance due to the conductive paste between the front electrode 5 and the back electrode 7 and the front electrode 6 and the back electrode 8 of the insulating substrate 1 can be reduced.
[0025]
Each of the leads 11, 12, and 13 may be individually molded, but for example, a flat hoop material such as copper or nickel is formed into a lead frame shape by press punching, etching, etc. A method of cutting and removing a tie bar portion (not shown) in which the other ends of the leads 11, 12, 13 are connected and integrated after the free ends of the leads 11, 12, 13 are connected to the electrodes 4, 5, 6 respectively. By adopting, there is an advantage that positioning of the leads 11, 12, 13 on the electrodes 4, 5, 6 is easy and reliable. The tie bar portion may be cut before or after fixing and sealing the insulating cap 19 described later.
[0026]
As shown in FIG. 11, a fusible alloy 17 is bridged between the upper surfaces of the inner ends of the leads 11 and 12. The fusible alloy 17 may be in the shape of a round bar, but a flat shape in which the round bar shape is crushed and has an oval cross section or a flat plate shape can reduce the height of the protective element A. desirable. The bridging of the fusible alloy 17 to the leads 11 and 12 can be performed by welding. The entire surface of the fusible alloy 17 is covered with a flux 18 having a slightly lower softening point (see FIGS. 1 and 5).
[0027]
As shown in FIGS. 1 and 2, an insulating cap 19 formed by molding ceramic, glass ceramic, glass, resin or the like is fixedly sealed by a sealing resin 20 above the flux 18 with a slight gap therebetween. It has been stopped.
FIG. 12 is a bottom perspective view of the insulating cap 19 and includes a top plate portion 19a having a shape and dimension sufficient to cover the flux 18, and a falling portion 19b from the peripheral portion of the top plate portion 19a. The box corresponding to the recessed stepped portion between the electrodes 4, 5 and the leads 11, 12 has a projection 19 c having a protruding dimension corresponding to the total thickness of the electrodes 4, 5 and the leads 11, 12. It is of shape.
[0028]
In the front view shown in FIG. 3, the state in which the insulating cap 19 is fixedly sealed is clearly shown. That is, the protrusion 19c of the insulating cap 19 is fitted between the electrodes 4 and 5 and the leads 11 and 12, and is sealed with the sealing resin 20 without a gap.
[0029]
According to the protective element A, the fusible alloy 17 is bridged between the upper surfaces of the inner ends of the leads 11 and 12, so that the resistance between the leads 11 and 12 includes the resistance of the electrodes 4 and 5. Since the value is irrelevant and can be ignored, the internal resistance of the protection element A can be reduced. Further, since the resistance values of the electrodes 4 and 5 can be ignored, the electrodes 4 and 5 can be formed thin, and the amount of expensive conductive paste used can be reduced, thereby reducing the cost.
[0030]
FIG. 13 is an equivalent circuit diagram of the protection element A having the above-described configuration.
That is, reference numerals 11, 12, and 13 indicate leads 11, 12, and 13 (or electrodes 4, 5, and 6), respectively, and reference numerals 7 and 8 indicate electrodes 7 and 8, respectively. A fuse F (soluble alloy 17) is connected between the leads 11 and 12, and a heater H (resistor 9) is connected between the electrodes 7 and 8. Here, the electrodes 5 and 7 and the electrodes 6 and 8 are connected to each other through the conductive layers formed in the through holes 2 and 3 of the insulating substrate 1 and the solders 15 and 16, respectively. A fuse F (fusible alloy 17) is connected, and a heater H (resistor 9) is connected between the leads 12 and 13.
[0031]
Next, an example of how to use the protection element A will be described.
FIG. 14 is a circuit diagram showing a case where the protection element A is applied to overcharge prevention in a lithium battery charging circuit. In FIG. 14, 21 and 22 are DC power supply terminals, and 23 and 24 are load terminals. A lithium battery 25 is connected to the load terminals 23 and 24. The lead 12 of the protection element A is connected to the DC power supply terminal 21, the lead 11 is connected to the positive terminal of the lithium battery 25, and the negative terminal of the lithium battery 25 is connected to the DC power supply terminal 22. A series circuit of resistors 26 and 27 constituting a charging terminal voltage detection circuit of the lithium battery 25 is connected in parallel to the lithium battery 25, and the lead 13 of the protection element A is connected to one terminal of the switching element 28 such as a transistor (illustrated example). And the other terminal (emitter in the illustrated example) of the switching element 28 is connected to the DC power supply terminal 22 (the negative terminal of the lithium battery 25). The connection point 29 between the resistors 26 and 27 is connected to the control terminal (base in the illustrated example) of the switching element 28.
[0032]
Next, the overcharge prevention operation in the lithium battery charging circuit of FIG. 14 will be described.
First, since the terminal voltage is low immediately after the start of charging of the lithium battery 25, the control terminal voltage of the switching element 28 is low. Therefore, the switching element 28 is held in the OFF state, and the fuse F (the fusible alloy 17) is connected. Accordingly, the lithium battery 25 is charged.
When the terminal voltage of the lithium battery 25 rises to a predetermined value due to charging, the control terminal voltage of the switching element 28 reaches its threshold value, and the switching element 28 becomes conductive. Then, the heater H (resistor 9) is energized through the switching element 28, and the heater H (resistor 9) generates heat. Due to the heat generated by the heater H (resistor 9), the fuse F (fusible alloy 17) is forcibly blown, and charging of the lithium battery 25 is stopped to prevent overcharging.
[0033]
Embodiment 2
FIGS. 15 to 18 show a protection element B made of a thin resistor-equipped fuse according to a second embodiment of the present invention. FIG. 15 is a plan view of the insulating cap and flux removed, that is, before flux application, and FIG. 17 is a left side view, and FIG. 18 is a bottom perspective view of the insulating cap.
15 to 18, the same reference numerals are given to the same parts as those of the protection element A of the first embodiment shown in FIGS. 1 to 8, and the description thereof is omitted. The protection element B of this embodiment is different from the protection element A in that the shape of the fusible alloy electrodes 34 and 35 formed on both ends of the insulating substrate 31 having the through holes 32 and 33 and the lead 41 and 42 and the shape of the insulating cap 49. That is, the electrodes 4 and 5 of the protective element A have an inverted L shape and a rectangular shape, whereas the electrodes 34 and 35 in the protective element B of this embodiment have their respective inner portions as is apparent from FIG. The width dimension of the one end is reduced to form a modified inverted L shape and T shape. The leads 41 and 42 are formed in a deformed reverse L-shape and a T-shape following the shape of the electrodes 34 and 35, and the leads 34 and 35 and the leads 41 and 42 As the shape is changed, as shown in FIG. 18, protrusions 49 c continuing from the falling portions 49 b at both ends in the short direction of the insulating cap 49 are formed over the entire length in the length direction of the insulating cap 49.
[0034]
As a result of the shape change, the positional relationship between the electrodes 34 and 35 and the leads 41 and 42 and the insulating cap 49 is apparent from FIG. , 42 is fixed and sealed to the insulating substrate 31 with a sealing resin 50.
[0035]
Also in the protection element B of this embodiment, the fusible alloy 17 is bridged on the leads 41 and 42, so that not only the same operational effects as described above but also both ends of the insulating cap 49 in the short direction can be obtained. Since the protrusion 49c is formed over the entire length of the insulating cap 49 in the longitudinal direction, the shape of the insulating cap 49 is simplified, and there is a feature that the manufacture of the mold and the manufacture of the insulating cap 49 are facilitated. Further, the reliability of sealing the insulating cap 49 with the sealing resin 50 is improved, and the reliability is also improved.
[0036]
Embodiment 3
19 to 22 show a protective element C made of a thin resistor-equipped fuse according to a third embodiment of the present invention. FIG. 19 is a front view partially showing a section, FIG. 20 is a left side view, FIG. Is a bottom view, and FIG. 22 is a bottom perspective view of the insulating cap.
19 to 22, the same parts as those of the protection element A of the first embodiment shown in FIGS. 1 to 12 and the protection element B of the second embodiment shown in FIGS. The description is omitted. The protective element C of this embodiment is different from the protective elements A and B in the insulating cap 69. That is, the insulating cap 69 has an internal dimension a in the short direction substantially the same as a width dimension in the short direction of the insulating substrate 1 (31), and a length dimension b in the longitudinal direction of the insulating cap 1 (31). The total dimension c of the falling part 69b and the protruding part 69c at both ends in the short direction is larger than the length dimension in the longitudinal direction of the insulating substrate 1 (31), the electrodes 4, 5 (34, 35), and the lead 11. , 12, 13 (41, 42, 43), fusible alloy 17, flux 18 and appropriate gap between flux 18 and insulating cap, electrodes 7, 8 on the back side of insulating substrate 1 (31), resistor 9 and It is set to a dimension equal to or greater than the total height dimension with the insulating film 10, and a step part 69d for supporting the insulating substrate 1 (31) is provided in the middle of the falling part 69b. .
[0037]
If the insulating cap 69 having such dimensions is used, the electrodes 4, 5 (34, 35), the leads 11, 12, 13 (41, 42, 43), the fusible alloy 17, and the flux 18 are completely covered with the insulating cap. 69, since the insulating substrate 1 (31) is supported by the step portion 69d of the insulating cap 69, between the flux 18 and the inner surface (lower surface) of the top plate portion 69a of the insulating cap 69, Appropriate gaps are easily and reliably formed. However, unlike the protection elements A and B of the first and second embodiments, the side portions are vacant, so the gap is filled and sealed with the sealing resin 70.
In this embodiment, the sealing resin 70 is filled and sealed only in the gap portion between the insulating substrate 1 (31) and the insulating cap 69. However, if necessary, the insulating substrate 1 The entire back side of (31) may also be filled and sealed with the sealing resin 70. By doing so, there is a feature that the sealing work by the sealing resin 70 becomes easy. If necessary, the insulating film 10 on the resistor 9 (on the lower surface) can be omitted by using the sealing resin 70 also as the insulating film 10 of the resistor 9.
[0038]
Also in this embodiment, the resistance value of the electrodes 4 and 5 can be ignored by bridging the fusible alloy 17 on the leads 11 and 12, so that the electrodes 4 and 5 can be formed thin and effective. Costs can be reduced by reducing the amount of conductive paste used. Further, the equivalent resistance between the leads 11 and 12 and the fusible alloy 17 can be reduced, and the fuse F (the fusible alloy 17) does not melt by heat generated by the equivalent resistance. Further, the external appearance shape of the protective element C as a whole is simplified, and it is difficult for an external force to act on the insulating caps 21 and 41, and the insulating caps 21 and 41 are not peeled off.
[0039]
In addition, although each said embodiment of this invention demonstrated the protection element of a specific structure, this invention is not limited to the structure shown in the said embodiment, In the range which does not deviate from the mind of this invention, Needless to say, various modifications are possible.
[0040]
For example, in each of the above embodiments, the case where the resistor 9 formed on the back surface of the insulating substrate 1 is covered and protected with the insulating film 10 has been described. However, the electrodes 7 and 8 for the resistor, 9 and the insulating film 10 can also be formed. In such a case, fusible alloy electrodes 4, 5 (34, 35) are formed on the insulating film 10, and leads 11, 12, 13 (41) are formed on the electrodes 4, 5 (34, 35). , 42, 43) can be fixed, and the soluble alloy 17 can be bridged on the leads 11, 12 (41, 42).
Thus, when the resistor is provided on the same side as the fusible alloy, the through holes 2 and 3 (32 and 33) of the insulating substrate 1 (31) are unnecessary.
[0041]
In any of the above-described embodiments, the fuse with a resistance including the fusible alloy 17 and the resistor 9 that forcibly melts the fusible alloy 17 by energization heat generation has been described. However, the insulating substrate 1 (31) The fuses 7 and 8, the resistor 9 and the insulating film 10 on the back surface or the front surface are omitted, and the fusible alloy 17 is made of a fusible alloy that melts in response to a predetermined ambient temperature. You may implement in the protective element called.
In this case, the electrodes 6 for connecting to the through holes 2 and 3 (32 and 33) of the insulating substrate 1 (31) and the resistor electrode 8 are also unnecessary.
[0042]
Moreover, although the said embodiment demonstrated the case where the surface of the insulated substrate 1 was exposed directly under the fusible alloy 17, it melt | dissolved rather than the insulated substrate 1 (31) between the electrodes 4 and 5 (44, 45). An insulating layer made of a material having poor wettability of the fusible alloy 17 may be formed to have the same thickness as the electrodes 4 and 5 (44, 45).
In such a case, when the fusible alloy 17 is melted, the melted fusible alloy 17 is repelled by the insulating layer. Therefore, the fusible alloy 17 is easily melted and spheroidized, and the fusing operation is quick and reliable. is there.
[0043]
【The invention's effect】
As described above, the present invention provides an insulating substrate, electrodes formed separately on the insulating substrate, leads fixed on these electrodes, and a fusible alloy fixedly connected on these leads. And a flux covering this fusible alloy and an insulating sealing material covering the flux, the internal resistance can be obtained by directly fixing and connecting the lead and the fusible alloy. The melting alloy is not melted by heat generated due to internal resistance. In addition, since there is no voltage drop due to the internal resistance, the supply voltage to the electronic device does not decrease. Furthermore, since the resistance value of the electrode can be ignored and the electrode can be formed thin, various excellent effects such as reduction in the amount of expensive conductive paste used and cost reduction can be achieved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a protection element A according to a first embodiment of the present invention.
FIG. 2 is a plan view of the protection element A according to the first embodiment of the present invention.
FIG. 3 is a front view of the protective element A according to the first embodiment of the present invention.
FIG. 4 is a left side view of the protective element A according to the first embodiment of the present invention.
FIG. 5 is a plan view of the protective element A according to the first embodiment of the present invention in which the insulating cap and the flux are removed.
FIG. 6 is a plan view of an insulating substrate in the protection element A according to the first embodiment of the present invention.
FIG. 7 is a plan view of an insulating substrate after formation of a soluble alloy electrode in the protective element A according to the first embodiment of the present invention.
FIG. 8 is a bottom view of an insulating substrate after forming a resistance electrode and a resistor in the protection element A according to the first embodiment of the present invention.
FIG. 9 is a bottom view of an insulating substrate after an insulating film is formed in the protective element A according to the first embodiment of the present invention.
FIG. 10 is a plan view of an insulating substrate after leads are fixed in the protective element A according to the first embodiment of the present invention.
FIG. 11 is a plan view of an insulating substrate after a fusible alloy bridge is formed in the protective element A according to the first embodiment of the present invention.
FIG. 12 is a bottom perspective view of the insulating cap in the protection element A according to the first embodiment of the present invention.
FIG. 13 is an equivalent circuit diagram of the protection element A according to the first embodiment of the present invention.
FIG. 14 is a charging circuit diagram of a lithium battery using the protection element A of the first embodiment of the present invention as an overcharge prevention circuit.
FIG. 15 is a plan view of an insulating substrate after leads are fixed in the protective element B according to the second embodiment of the present invention.
FIG. 16 is a front view of a protection element B according to a second embodiment of the present invention.
FIG. 17 is a left side view of a protection element B according to a second embodiment of the present invention.
FIG. 18 is a bottom perspective view of an insulating cap in a protection element B according to a second embodiment of the present invention.
FIG. 19 is a front view showing a part of the protective element C according to the third embodiment of the present invention in cross section.
FIG. 20 is a left side view of a protection element C according to a third embodiment of the present invention.
FIG. 21 is a bottom view of the protection element C according to the third embodiment of the present invention.
FIG. 22 is a bottom perspective view of an insulating cap in a protection element C according to a third embodiment of the present invention.
FIG. 23 is a longitudinal sectional view of a conventional thin protective element D
FIG. 24 is a plan view of the conventional thin protective element D before flux application, that is, the state in which the insulating cap and the flux are removed so that the internal structure can be seen.
FIG. 25 is a longitudinal sectional view of another conventional thin protective element E.
FIG. 26 is a plan view of a state before flux application in another conventional thin protective element E, that is, a state in which the insulating cap and the flux are removed so that the internal structure can be seen.
[Explanation of symbols]
1,31 Insulating substrate
2, 3, 32, 33 Through hole
4, 5, 34, 35 Electrode for fusible alloy
6, 36 Relay electrode
7, 8 Electrodes for resistors
9 resistors
10 Insulating film
11, 12, 13, 41, 42, 43 Lead
14, 15, 16 Solder
17 Soluble alloy
18 Flux
19, 49, 69 Insulation cap
19a, 49a, 69a Top plate
19b, 49b, 69b Falling part
19c, 49b, 69c Projection
20, 50, 70 Sealing resin
69d Step

Claims (2)

Insulating substrate, electrodes formed on both ends of the surface of the insulating substrate , leads fixed on these electrodes, a fusible alloy bridged on these leads, and this fusible A flux covering the alloy; and an insulating cap fixed to the insulating substrate by a sealing resin covering the fusible alloy and the flux. The insulating cap includes a top plate portion, a falling portion, and the lead. A protective element having a protrusion corresponding to the lead thickness in a portion corresponding to the gap therebetween . The inner dimension of the insulating cap in the short direction is formed substantially the same as the width dimension in the short direction of the insulating substrate, and the total dimension of the falling part and the protruding part is the insulating substrate, electrode, The protective element according to claim 1, wherein the protective element is set to be equal to or greater than a total height dimension of the lead, the fusible alloy, and the flux.

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