JP2000243200A - Safety device for electric circuit and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To surely prevent an accident by a thermal fuse when an overcurrent protection element is abnormally overheated. A PTC element (overcurrent protection element) 20 as first protection means for protecting an electric circuit from overcurrent, and a PTC element
A second protection means provided near the element, the first electrode 31a of the conductor pattern 31 connected to the PTC element 20;
And a second electrode 32a of the conductor pattern 32 insulated by a gap 33, and a thermal fuse 30 made of a solder 34 bridging the two electrodes and melting by the heat of the PTC element to separate the two electrodes.
And Alternatively, the solder may be loaded into the through hole of the circuit board, and the solder may have a concave portion on one opening side of the through hole and a convex portion on the other opening side, and bridge the two electrodes with the convex portion. The inner diameter of the through hole is larger than the thickness of the circuit board.
The outer diameter of the exposed conductor portion of the circuit board on the concave side may be larger than the outer diameter of the second electrode. The circuit board is arranged vertically or with the protrusions facing upward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for an electric circuit for preventing an accident due to an overcurrent of the electric circuit and a method of manufacturing the same. In this case, the present invention relates to a safety device for an electric circuit for surely preventing accidents by using a thermal fuse as a second protection means, and a method for manufacturing the same.

[0002]

2. Description of the Related Art An electric circuit such as a power supply box mounted on an electric vehicle is provided with an overcurrent protection element for preventing an accident due to an overcurrent. As an overcurrent protection element,
For example, PTC (Positive Temperture Coefficient)
Elements, varistors, aluminum electrolytic capacitors, and the like are used, all of which generate heat when an overcurrent flows, increase resistance, reduce or cut off the overcurrent, and maintain the safety of an electric circuit.

However, when the overcurrent continues to flow and the overcurrent protection element abnormally overheats, if this state is left unchecked, the overcurrent protection element may ignite and cause a vehicle fire. Therefore, various measures have conventionally been proposed to cope with abnormal overheating of the overcurrent protection element.

For example, in JP-A-8-250304,
As shown in FIG. 13, one of a pair of leads 112 and 113 soldered to the PTC element 111 has a PTC element 11 attached thereto.
A safety device 110 for an electric circuit which has a spring property in a separating direction with respect to the electric circuit 1 has been proposed.

According to such a configuration, P
When the TC element 111 is overheated abnormally, the solder melts and one of the leads 112 jumps up and separates from the PTC element 111. Thereby, the overcurrent flowing in the electric circuit is cut off.

[0006] In Japanese Utility Model Laid-Open No. 1-129744, as shown in FIG.
Safety device 12 for electric circuit using 121
0 has been proposed. Safety device 120 for this electrical circuit
Is formed by bending a lead 122 of a ZNR 121 at a right angle, soldering the lead 122 to one and other conductor patterns 123 and 124 which are insulated from each other on a circuit board, and connecting these one and other conductor patterns 123 and 124 to each other. It is configured to be electrically connected.

According to such a structure, FIGS.
As shown in (c), when the ZNR 121 is abnormally overheated due to the overcurrent, the solder for fixing the lead 122 is melted, the ZNR 121 falls off by its own weight, and the conduction between one and the other conductor patterns 123 and 124 is cut off. You. by this,
The overcurrent flowing in the electric circuit is also cut off.

[0008]

However, in the above-described conventional safety devices 110 and 120 for each electric circuit, accidents due to abnormal overheating of the overcurrent protection element can be prevented, but the following problems arise. there were.

In the safety device 110 for an electric circuit shown in FIG. 13, soldering must be performed against the elastic force of the lead 112, which requires time and labor for the soldering operation. There is a problem that it cannot be easily manufactured.

[0010] In the safety device 120 for an electric circuit shown in FIG.
As described above, there is a problem that the soldering operation requires labor and time, and cannot be easily manufactured by an automatic soldering device or the like.

Therefore, as a result of intensive studies by the present inventors, a temperature fuse is provided near the overcurrent protection element,
The technical idea has been reached that the overheating of the overcurrent protection element can be detected by the thermal fuse and the electric circuit can be interrupted.

Here, for a general thermal fuse,
This will be described with reference to FIGS. 15 (a), (b) and (c).
As shown in FIG. 15A, one conductor pattern 132 and another conductor pattern 133 are formed on the circuit board 131, and the electrodes 132a and 133a of the one and other conductor patterns 132 and 133 are , Gap (interval) 134
Is insulated. Then, as shown in FIG. 15B, the temperature fuse 130 is formed by bridging (connecting and connecting the electrodes 132a, 133a with a solder 135) so as to bridge.

According to such a configuration, when the ambient temperature around the one or other conductor patterns 132 and 133 and the solder 135 becomes high, the solder 135 is completely melted. Then, as shown in FIG.
Are repelled by the substrate surface in the gap 134 that is not easily wetted and are easily wetted by surface tension.
33a. As a result, conduction between the first and second conductor patterns 132 and 133 is interrupted, and accidents due to abnormal overheating of the electric circuit are prevented.

However, the conventional thermal fuse 1 described above
In step 30, when the thermal fuse 130 is formed, the solder 135 is brought into a state close to complete melting, and the electrodes 132a,
At this time, the solder 135 is separated into the electrodes 132a and 133a, and the solder 135 in a state of being almost completely melted is separated from the electrodes 132a and 133a.
a, 133a. Therefore, there is a problem that the thermal fuse 130 cannot be easily formed by an automatic soldering device or the like at the same time as the soldering of the other electric components.

Such a problem is caused by the gap 134 between the electrodes 132a and 133a, as shown in FIG.
Since it is continuous in the direction of the arrow in the figure, in other words, since there is no electrode to stop the solder 135 melted in the direction of the arrow in the figure,
On the surface of the substrate in the gap 134, the molten solder 1
It is considered that 35 is difficult to stabilize.

However, the molten solder 135 is
Since the property of being easily separated into 2a and 133a contributes to the reliability as a fuse at the time of abnormal overheating of the electric circuit, the molten solder 135 is applied to each of the electrodes 132a and 133a only when the thermal fuse 130 is formed. It is necessary to avoid separation.

Incidentally, in order to solve the above problem, Japanese Patent Laid-Open No.
No. 56028 proposes a thermal fuse in which each electrode of one and other circuit patterns separated and insulated on a circuit board is bridged by a porous solder layer in which a space between solder particles remains.

However, in order to form a porous solder layer,
A special process such as printing solder cream on the circuit board and then semi-melting this solder cream must be performed. Cannot be formed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and when an overcurrent protection element which is a first protection means is overheated abnormally, a reliable accident prevention is performed by a thermal fuse which is a second protection means. The temperature fuse can be quickly operated when the overcurrent protection element is abnormally heated, and the temperature fuse can be easily formed by an automatic soldering device or the like. An object of the present invention is to provide a safety device and a manufacturing method thereof.

[0020]

In order to achieve the above object, a safety device for an electric circuit according to claim 1 is a first protection means for protecting an electric circuit from an overcurrent. An overcurrent protection element that generates heat when a current flows to increase resistance and reduces or cuts off overcurrent, and a second protection means provided near the overcurrent protection element, A first electrode of one conductor pattern connected to the protection element, a second electrode of another conductor pattern insulated from the first electrode by a gap, and bridging the first and second electrodes to provide the overcurrent protection; It is configured to include a temperature fuse made of solder that is melted by heat from the element and separated on the first and second electrode sides.

According to such a configuration, when the overcurrent protection element is abnormally overheated by the overcurrent, the heat causes the thermal fuse to operate, thereby interrupting the electric circuit. Thus, an accident such as a vehicle fire due to abnormal overheating of the overcurrent protection element can be reliably prevented.

Preferably, the resist film around the thermal fuse is peeled off by the heat from the overcurrent protection element, as in a safety device for an electric circuit according to a second aspect of the present invention.

According to such a configuration, when the solder forming the thermal fuse is melted, the solder is sucked between the peeled resist film and the substrate surface, so that one conductor pattern is cut off more quickly. Can be. Thus, when the overcurrent protection element is abnormally overheated, the thermal fuse can be quickly operated to more reliably prevent an accident.

Preferably, when the circuit board on which the overcurrent protection element and the thermal fuse are mounted is installed vertically, as in the safety device for an electric circuit according to claim 3, the thermal fuse protects the overcurrent protection. The structure is such that it is located substantially the same as the element or above the overcurrent protection element.

According to such a configuration, heat conduction from the overcurrent protection element to the thermal fuse is improved due to the relationship between the overcurrent protection element as a heat source and the thermal fuse. That is, when the thermal fuse is provided at substantially the same position as the overcurrent protection element, the heat of the overcurrent protection element is directly transmitted to the thermal fuse, and when the thermal fuse is provided above the overcurrent protection element, the temperature is low. The heat of the overcurrent protection element at the position is efficiently transmitted to the thermal fuse at a higher position. In addition, since the circuit board is arranged vertically, the solder melted by the heat of the overcurrent protection element actively flows downward by its own weight. Thereby, when the overcurrent protection element is abnormally overheated, one and the other conductor patterns can be cut off more quickly, that is, the temperature fuse can be operated quickly, and more reliable accident prevention can be achieved. .

Preferably, a hole is formed in a gap between the first and second electrodes forming the thermal fuse, and a lead of an electric component is formed in the hole, as in the safety device for an electric circuit according to claim 4. And the first and second electrodes are bridged with solder together with the leads.

According to such a configuration, the solder for bridging the first and second electrodes adheres to the lead of the electric component, so that the solder can easily be put between the first and second electrodes, and the ordinary With solder, at the same time as soldering other electrical components,
A thermal fuse can be easily formed by an automatic soldering device or the like.

Further, it is not necessary to provide an independent thermal fuse, so that the number of soldering points on the entire circuit board is reduced, and workability and reliability can be improved.

Preferably, the electric component is configured as the overcurrent protection element, as in a safety device for an electric circuit according to a fifth aspect of the present invention.

According to such a configuration, the heat of the overcurrent protection element is transmitted to the lead and acts directly on the thermal fuse, so that when the overcurrent protective element is abnormally heated, the thermal fuse operates more quickly. Can be.

Preferably, the another conductor pattern forming the thermal fuse is formed on one surface of the circuit board, and the other conductor pattern is formed through the other conductor pattern. Via a hole, continuous with the land-shaped second electrode formed on the other surface of the circuit board,
On the other surface of the circuit board, the second electrode is continuously surrounded by the first electrode with a gap, and the first and second electrodes are bridged by solder.

According to such a configuration, if the inside of the first electrode is not interrupted, the solder in a state of almost complete melting can be stopped by the first electrode. On the gap, it is possible to stabilize the solder in a state close to complete melting. This makes it possible to easily form a thermal fuse with an automatic soldering device or the like at the same time as soldering other electrical components with ordinary solder.

When the overcurrent protection element is abnormally overheated,
Since the completely melted solder is separated into the first and second electrodes, and the conduction of one and the other conductor patterns is interrupted,
High reliability as a fuse.

Preferably, as in the safety device for an electric circuit according to claim 7, the second electrode forming the thermal fuse has a land shape formed on the periphery of a hole for inserting a lead of an electric component. The second electrode is surrounded by the first electrode with a gap therebetween without interruption, and the first and second electrodes are bridged with solder together with the leads of the electric component inserted through the holes.

According to such a configuration, the solder for bridging the first and second electrodes adheres to the lead of the electric component, so that the solder is compared with the thermal fuse in the safety device of the electric circuit according to the sixth aspect. Thus, the solder is more easily put between the first and second electrodes.

Further, both surfaces of the circuit board are used.
In contrast to the thermal fuse in the electrical circuit safety device according to the present invention, in the electrical circuit safety device according to the seventh aspect, the thermal fuse can be formed on only one surface of the circuit board, and the circuit board can be simplified. it can.

Preferably, as in the safety device for an electric circuit according to claim 8, the first electrode forming the thermal fuse is formed on a peripheral edge of a hole for inserting a lead of the overcurrent protection element. In a land shape, the first electrode is continuously surrounded with a gap by the second electrode, and the first and second electrodes are bridged with solder together with the lead of the overcurrent protection element inserted through the hole. Configuration.

According to such a configuration, the heat of the overcurrent protection element directly acts on the thermal fuse by transmitting through the lead. In comparison, when the overcurrent protection element is abnormally heated, the thermal fuse can be operated more quickly.

Preferably, the overcurrent protection element is a PTC element as in a safety device for an electric circuit according to a ninth aspect.

A PTC element, particularly a low-resistance PTC element, is an overcurrent protection element suitable for an electric circuit such as a power supply box mounted on an electric vehicle, and the PTC element is any one of claims 1 to 8. The safety device for an electric circuit according to the present invention can be made particularly suitable for an electric vehicle by using it as an overcurrent protection element constituting the safety device for an electric circuit.

To achieve the above object, a method for manufacturing a safety device for an electric circuit according to claim 10 is a method for manufacturing a safety device for an electric circuit according to any one of claims 4 to 8,
A device for automatically soldering electrical components on the circuit board including the overcurrent protection element, simultaneously with soldering these electrical components, bridging the first and second electrodes with solder, Is formed.

According to such a method, it is possible to easily form the thermal fuse with the same solder as the connection of the other electric components and at the same time as the soldering of the other electric components by an automatic soldering device or the like. It is possible to manufacture a safety device for an electric circuit at low cost without requiring any special manufacturing process as in the related art.

Further, as in the electric circuit safety device according to the eleventh aspect, the solder is loaded in the through hole of the circuit board, and the solder is recessed in one opening side of the through hole and in the other opening side. It is also effective to have a convex portion, and the convex portion bridges the first electrode and the second electrode.

According to this structure, when the solder is melted at an abnormally high temperature, the convex portion of the solder moves toward the concave portion side (pulls in) and the connection between the two electrodes is quickly and reliably performed. Will be released.

Preferably, the inner diameter of the through hole is set to be larger than the plate thickness of the circuit board. With such a configuration, the speed at which the solder protrusions are drawn into the through-holes is increased, and the interruption of the circuit is further expedited. Further, at the time of manufacturing, the concave portion and the convex portion are easily and reliably formed by the weight of the molten solder.

Preferably, the outer diameter of the exposed conductor portion of the circuit board on the concave side is at least larger than the outer diameter of the second electrode near the through hole. Set larger.

With this configuration, when the solder melted at an abnormally high temperature moves to the concave side, it is attracted to the exposed conductor having good wettability, so that the solder moving speed is increased, and the circuit breaking speed is reduced. As it increases, the interruption of the circuit is further ensured. Preferably, as in the safety device for an electric circuit according to claim 14, the circuit board is disposed vertically, or the circuit board is disposed with the convex portion facing upward.

By arranging the circuit board vertically, the solder melted at the time of abnormality is reliably sucked into the through hole.
Further, by arranging the circuit board with the convex portion facing upward, the convex portion moves quickly to the concave portion due to the weight of the solder, thereby increasing the circuit breaking speed and further ensuring the circuit breaking.

According to a fifteenth aspect of the present invention, there is provided a method of manufacturing a safety device for an electric circuit according to any one of the eleventh to fourteenth aspects, wherein the circuit board is positioned horizontally and vertically. The molten solder is loaded into the through hole, and the concave portion and the convex portion are formed by the own weight of the solder. According to this method, the concave portion and the convex portion can be easily formed by the own weight of the solder, and the manufacturing cost of the thermal fuse can be reduced.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an electric circuit safety device and a method of manufacturing the same according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a safety device for an electric circuit according to a first embodiment of the present invention. 2A and 2B show a safety device for the electric circuit, wherein FIG. 2A is a front view and FIG. 2B is a rear view. FIG. 3 is a sectional view of only the circuit board constituting the safety device for the electric circuit. FIG. 4 shows only the circuit board, and FIG.
FIG. 2B is a rear view. 5 (a), (b),
(C) is a front view showing an operation state of a thermal fuse constituting a safety device for the electric circuit.

In FIGS. 1 and 2 (a) and 2 (b), a safety device 1 for an electric circuit according to the present embodiment includes a PTC element (overcurrent protection element) 20 provided close to a circuit board 10 and a temperature. It consists of a fuse 30.

The PTC element 20 is a first protection means for protecting an electric circuit from an overcurrent, and generates heat when an overcurrent flows through the electric circuit to increase the resistance and reduce or cut off the overcurrent. Fulfill.

Such a PTC element 20 is connected to the circuit board 1
The leads 21 and 21 are inserted into the holes 11 and 11 formed in the circuit board 10 and the leads 21 and 21 are connected to the back surface (other surface) of the circuit board 10.
The electrodes are soldered to the electrodes of the two conductor patterns (one of which is one conductor pattern 31 described later) formed in 10B.

The thermal fuse 30 is a second protection means provided near the PTC element 20.
The one conductor pattern 31 connected to the PTC element 20
Of the first electrode 31a and the gap 33 with the first electrode 31a
Electrode 32 of another conductor pattern 32 insulated by
a is bridged by a solder 34.

Specifically, FIGS. 1 and 2 (a) and 2 (b),
3 and 4 (a) and (b) corresponding to these drawings.
As shown in the figure, one conductor pattern 31 is formed on the back surface 10B of the circuit board 10 as described above, and the other conductor pattern 32 is formed on the front surface (one surface) 10A of the circuit board 10 as described above. is there. The other conductor pattern 32
Is connected to the circuit board 1 through the elongated through hole 32b.
0 is continuous with the land-shaped second electrode 32a formed on the back surface 10B.

As shown in FIGS. 4B and 5A, the first electrode 31a of one conductor pattern 31 surrounds the second electrode 32a without a gap 33 with no gap. These first and second electrodes 31a, 32a
1 and 2 (b) and FIG.
As shown in (b), a thermal fuse 30 is formed.

Returning to FIG. 1, both sides 10 of the circuit board 10 will be described.
A and 10B are covered with a resist film 40 except for all electrodes and lands including the first and second electrodes 31a and 32a. In the present embodiment, when the PTC element 20 abnormally overheats, the PTC The resist film 40 around the thermal fuse 30 is peeled off by the heat from the element 20.

As a configuration for stripping the resist film 40 around the thermal fuse 30, first, the PT at the time of abnormal overheating is set.
The PTC element 20 and the thermal fuse 30 need to be provided close to each other so that the heat of the C element 20 can be sufficiently transmitted to the thermal fuse 30.

In addition to this, the resist film 40 is heated by the PTC element 20 at the time of abnormal overheating (generally, about 1000 ° C.).
Depending on the strength, it is necessary to have a strength capable of peeling. As a result of experiments performed by the inventors, the resist film 40 (a peel strength of に 対 し て with respect to heat of 300 ° C. or more) used for a normal circuit board can be sufficiently peeled.

In FIG. 1, in the present embodiment, the circuit is laid out so that the thermal fuse 30 is located above the PTC element 20 with the circuit board 10 installed vertically.

Here, a method of manufacturing the safety device for an electric circuit according to the present embodiment will be described. The safety device 1 for an electric circuit is configured by using an automatic soldering device (not shown) by using another electric component on a circuit board 10 (not shown). Is formed at the same time as soldering.

That is, the PTC element 2 is placed on the circuit board 10.
0, including all electrical components, for example, by a jet-type automatic soldering device, soldering these electrical components,
Formation of thermal fuse 30 (first and second electrodes 31a, 3a)
2a) and at the same time.

Next, the operation of the electric circuit safety device 1 according to the present embodiment having the above-described configuration will be described with reference to FIGS.
This will be described with reference to (b) and (c). In FIG.
When an overcurrent flows through the electric circuit, the PTC element 20 generates heat to increase the resistance and reduce or cut off the overcurrent. This usually keeps the electrical circuit safe.

However, the overcurrent continues to flow after that, and PT
When the C element 20 is overheated abnormally, heat from the PTC element 20 is transmitted through the lead 21 and the one conductor pattern 31.
The signal is transmitted to the thermal fuse 30 side. The heat at this time is efficiently transmitted from the PTC element 20 at a lower position to the thermal fuse 30 at a higher position on the circuit board 10 installed vertically.

When the heat from the PTC element 20 is transmitted to the thermal fuse 30, the first and second electrodes 31a, 32a
Is completely melted, and the resist film 40 around the thermal fuse 30 is peeled off by heat (see FIG. 5B). In particular, the resist film 40 below the thermal fuse 30 near the PTC element 20 as the heat source is remarkably peeled off.

Then, as shown in FIG. 5C, the molten solder 3 is placed between the peeled resist film 40 and the substrate surface.
4 and at the same time, the remaining solder 34
Is repelled. In particular, since the circuit board 10 is installed vertically, the peeled resist film 4 under the thermal fuse 30 is removed.
The molten solder 34a actively flows downward between the zero and the substrate surface by its own weight.

As a result, the first and second electrodes 31a, 32
The solder 34 bridging a is separated from the first and second electrodes 31a and 32a, which are easily wetted, so that conduction between the first and second conductor patterns 31 and 32 is cut off.

The safety device 1 for an electric circuit according to the present embodiment has the following excellent effects. First, even if the PTC element 20 serving as an overcurrent protection element is abnormally overheated due to an overcurrent, the heat causes the thermal fuse 30 to operate and cut off the electric circuit. Thus, an accident such as a vehicle fire due to abnormal overheating of the PTC element 20 can be reliably prevented.

Second, the PTC element 20 and the thermal fuse 3
0 are provided close to each other so that the resist film 40 around the thermal fuse 30 is peeled off when the PTC element 20 is abnormally overheated. It is sucked between the substrate surface and the first and other conductor patterns 31 and 32 can be cut off quickly. Thus, when the PCT element 20 is abnormally overheated, the thermal fuse 30 is quickly operated, and more reliable accident prevention can be achieved.

Third, the circuit board 10 is installed vertically, and the thermal fuse 30 is located above the PTC element 20, so that heat conduction from the PTC element 20 as a heat source to the thermal fuse 30 is good. When the solder 34 forming the thermal fuse 30 is melted, the solder 34
Flows positively downward by its own weight, and the lower resist film 40 is remarkably peeled off, so that one and the other conductor patterns 31 and 32 can be cut off more quickly. Thereby, when the PTC element 20 is abnormally overheated, the temperature fuse 3
0 can be operated more quickly, and more reliable accident prevention can be achieved.

Fourth, since the first electrode 31a forming the thermal fuse 30 surrounds the second electrode 32a without a gap with a gap 33, the first electrode 31a without a break is formed.
If it is inside a, the solder 34 in a state close to complete melting,
Since the first electrode 31a can be stopped, the solder 34 in a state close to complete melting can be stabilized on the gap 33 between the first and second electrodes 31a and 32a. Thus, the thermal fuse 30 can be easily formed by the automatic soldering device or the like simultaneously with the soldering of other electric components by the normal solder 34.

When the PTC element 20 is overheated abnormally,
The completely melted solder 34 is applied to the first and second electrodes 31a, 3a.
2a, and one and the other conductor patterns 31,
Since the conduction of 32 is cut off, the reliability as a fuse is high.

On the other hand, according to the method for manufacturing a safety device for an electric circuit according to the present embodiment, an automatic soldering device or the like is used.
The thermal fuse 30 can be easily formed with the same solder 34 as the connection of the other electric components and at the same time as the soldering of the other electric components, and does not require any special manufacturing process as in the prior art. Safety devices for electric circuits can be manufactured at low cost.

Next, a safety device for an electric circuit according to a second embodiment of the present invention will be described. FIG. 6 is a sectional view showing a safety device for an electric circuit according to a second embodiment of the present invention.
FIG. 7 is an explanatory view showing a conductor pattern of a thermal fuse in the safety device for an electric circuit.

In these figures, in the safety device 2 for an electric circuit of the present embodiment, the P
A first electrode 51a of one conductor pattern 51 connected to the TC element 20 and a second electrode 52a of another conductor pattern 52 insulated from the first electrode 51a by a gap 53 are formed.

The first and second electrodes 51a, 51a,
While drilling the hole 11 in the gap 53 between 52a,
A lead 61 of an electric component 60 is inserted through the hole 11, and the first and second electrodes 51 a and 52 a are bridged with the lead 61 by a solder 54 to form a thermal fuse 50.

According to such a configuration, the solder 54 for bridging the first and second electrodes 51a and 52a is not
Since the first and second electrodes 51a and 52a are attached to the lead 61, the solder 54 can be easily mounted between the first and second electrodes 51a and 52a. Thus, the soldering of the electric component 60 with the normal solder 54 and the temperature fuse 5 can be easily performed by an automatic soldering device or the like.
0 can be formed.

Further, it is not necessary to provide an independent thermal fuse (for example, the thermal fuse 30 in the first embodiment), so that the number of soldering locations on the entire circuit board 10 is reduced, and workability and reliability are improved. Can be.

Further, both sides 10A, 10A of the circuit board 10
In contrast to the thermal fuse 30 (see FIG. 1) in the electric circuit safety device 1 of the first embodiment utilizing the B, in the electric circuit safety device 2 of the present embodiment, only one side 10B of the circuit board 10 has a temperature. Fuse 50 can be formed;
The circuit board 10 can be simplified.

Next, a safety device for an electric circuit according to a third embodiment of the present invention will be described. FIG. 8 is a sectional view showing a safety device for an electric circuit according to a third embodiment of the present invention.
In these drawings, an electric circuit safety device 3 of the present embodiment is an electric circuit safety device 1 (FIG. 1) according to the first embodiment.
And the safety device 2 for an electric circuit according to the second embodiment.

In summary, the thermal fuse 70 having a configuration similar to the thermal fuse 30 in the first embodiment is
It is characterized in that it is formed around the hole 11 through which the lead 21 of the C element 20 is inserted.

Specifically, a land-like first electrode 71 a (= one conductor pattern 7) connected to the lead 21 of the PTC element 20 is provided on the periphery of the hole 11 on the back surface of the circuit board 10.
1) is formed. Then, the land-shaped first electrode 7
1a is surrounded by the second electrode 72a of the other conductor pattern 72 without gaps without gaps. The first and second electrodes 71a, 72
The appearances of a and the hole 11 are exactly the same as those in FIG. 5A of the first embodiment.

The first and second electrodes 71a, 72a
Is bridged with solder 74 together with the lead 21 of the PTC element 20 inserted through the hole 11, so that the temperature fuse 7
0 is formed.

According to such a configuration, the PTC element 20
Is applied to the thermal fuse 70 directly through the lead 21, so that the PTC element 20 differs from the thermal fuses 30 and 50 in the safety devices 1 and 2 of the electric circuit of the first and second embodiments. In the case of abnormal heating, the temperature fuse 70 can be operated more quickly.

Also, since the solder 74 for bridging the first and second electrodes 71a and 72a adheres to the lead 21 of the PTC element 20, the solder 74 in the safety devices 1 and 2 of the first and second embodiments can be used. Compared to the thermal fuses 30 and 50, the solder 7 is provided between the first and second electrodes 71a and 72a.
4 becomes easier to ride.

Further, similarly to the safety device 2 for an electric circuit according to the second embodiment, the number of soldering points of the circuit board 10 as a whole can be reduced, and workability and reliability can be improved. Can form the thermal fuse 70 only on one side 10B of the circuit board 10B.
Can be simplified.

The safety device for an electric circuit according to the present invention is not limited to the above embodiments.

First, the overcurrent protection element, which is the first protection means, is not limited to the above-described PTC element 20, but generates heat when an overcurrent flows through the electric circuit to increase the resistance, thereby reducing or reducing the overcurrent. As long as it can shut off, other elements such as a varistor and an aluminum electrolytic capacitor may be used.

The temperature fuse 50 in the safety device 2 for an electric circuit according to the second embodiment described above (see FIG. 6).
Is directly used as the safety device 3 for the electric circuit according to the third embodiment.
Of the thermal fuse 70 (see FIG. 8), and vice versa.

FIGS. 9 and 10 are sectional views showing a safety device for an electric circuit according to a fourth embodiment of the present invention. The PTC element 20 (FIG. 1) and the electric component 60 in the above-described embodiment are used.
(FIG. 2) and the like are not shown.

As shown in FIG. 9, the safety device 4 for an electric circuit includes a solder 8 in a through hole 81 provided in a circuit board 80.
2, a recess 83 is formed in the solder 82 on one opening 81a side of the through hole 81, and the through hole 81 is formed.
On the other opening 81b side, a convex portion 84 is formed in the solder 82, and as shown in FIG. 10, when the solder 82 is melted, the convex portion 82 flows into the through hole 81 toward the concave portion 83 (FIG. 9), and A temperature fuse 88 (FIG. 9) is configured to release the solder connection between the first electrode 85 and the second electrode 86 of the circuit board 80 by pulling the portion 84 side.

In FIG. 9, the circuit board 80 is disposed horizontally with the component mounting surface 80A facing upward. Components refer to the PTC element 20 (FIG. 1), the electrical component 60 (FIG. 2), and the like. The through-hole 81 is located vertically, and the solder 82 in the through-hole 81 is projected downward by the gravity during melting.
4 and a concave portion 83 is formed on the upper side. Convex part 84
Has a large-diameter curved surface 84a, and the concave portion 83 has a small-diameter curved surface 83a. Each of the curved surfaces 83a and 84a has a spherical shape, and is generated by the surface tension of the solder 82 at the time of melting. The inside of the through hole 81 has good wettability of the solder 82 due to the conductor portion 89 on the inner peripheral side, and the mobility of the solder 82 is good.

The conductor 89 in the through-hole 81 follows the second electrode 86 at the opening edge of the through-hole 81 on the solder surface 80B side (lower surface side) of the circuit board 80, and has a narrow gap outside the second electrode 86. The first electrode 85 is formed via the first electrode 85. The first electrode 85 follows the first conductor pattern 90, and the second electrode 86 is a short exposed conductor portion 9 on the component mounting surface side.
6 and continues to the second conductor pattern 91. The electrodes 85 and 86 and the gap 87 are annular as shown in the embodiment of FIG.

On the component mounting surface side of the circuit board 80, a solder resist film 92 is formed on the second (other) conductor pattern 91, and on the solder surface side, a solder resist film 92 is formed on the first (one) conductor pattern 90. A film 93 is formed. The solder resist film (hereinafter simply referred to as a resist film) 92 on the component mounting surface side is extended to a position near one opening 81a of the through hole 81, and the resist film 93 on the solder surface side is slightly extended from the other opening 81b of the through hole 81. It is located far away outside the gap 85. That is, the end 93a of the resist film 93 on the solder surface side is farther from the through hole 81 in the radial direction than the end portion 92a of the resist film 92 on the component mounting surface side.

As a result, the protrusion 84 on the lower side of the solder 82 extends over the gap 85 to a large diameter up to the end 93a of the resist film 93. The solder 82 does not enter the narrow gap 87 due to its surface tension. Even if it enters, the surface of the insulating substrate body 95 is
Molten solder 8 because of poor wettability (bonding property)
2 easily disengages from gap 87. The temperature fuse 88 is formed by connecting the first electrode 85 and the second electrode 86 with the solder 82 over the gap 87. Solder 8
The upper end of the recess 83 on the upper side is located at the opening end of the through hole 81, and does not protrude higher than the opening 81a.

The solder 82 is filled in the through hole 81 by, for example, jet soldering. By jet soldering, the molten solder 82 is blown up like a fountain in a flow furnace, and the surface of the circuit board 80 is brought into contact with the molten solder 82 while moving the circuit board 80 therein.
In this method, the solder 82 is attached to each metal conductor of the circuit board 80. At this time, the solder is sucked up and filled in the through hole 81 due to the wettability of the conductor 89 in the through hole 81. PTC element 20 in the jet soldering process (Fig. 1)
Are also soldered to the circuit board 80 at the same time.

In the jet soldering, the through holes 81
Inner diameter D₁Is the thickness T of the circuit board 80 ₁If less than
Fig. 9 shows the surface tension of the solder in the through hole.
Such a concave portion 83 is not formed, and conversely, the bulging portion 97 of FIG.
Will protrude like Therefore, the through hole 81
Inner diameter (Strictly, inner diameter of conductor 89 in through hole) D
Is the thickness of the circuit board 80 (strictly speaking, a board including a resist film).
Thickness) T₁It is set larger than. This is the manufacturing of FIG.
In the process, the surface tension of the molten solder 82 is overcome,
By the weight of the rice pad 82, the concave portion 83 is sufficient on the upper side and the convex portion 84 is
This is a necessary condition for forming a large size. Through Ho
Internal diameter D₁Is the thickness T of the circuit board 80 ₁Smaller than
In this case, the upper concave portion 83 is formed by the surface tension of the solder 82.
And the lower convex portion 84 are hardly formed. In this state,
Even if the solder 82 melts due to the constant heat generation, the circuit (conductor
Turns 90 and 91 are difficult to open. Also through
Inner diameter D of hole 81₁Is the thickness T of the circuit board 80.₁than
By setting a large value, it melts at an abnormally high temperature in FIG.
Solder 82 is easily drawn into through hole 81
As a result, the circuit breaking speed increases.

The temperature fuse 88 is formed with the circuit board 80 horizontal as shown in FIG. 9, and the circuit board 8 is formed as shown in FIG.
The thermal fuse 88 (FIG. 9) is used with 0 being vertical. FIG. 10 shows that the temperature of the PTC element 20 (FIG. 1) on the circuit board 80 becomes abnormally high, the solder 82 melts, and the connection portions of the electrodes 85 and 86 of the conductor patterns 90 and 91 are opened (the electrodes 85 , 86 are disconnected).

That is, when the solder 82 having the concave portion 83 and the convex portion 84 shown in FIG.
As shown in FIG. 10, the convex portion 84 is reduced in diameter, and the skirt portion 84b of the convex portion 84 is separated from the first electrode 85 inward and crosses the gap 87 so that the second electrode 82 is removed. Move to 86 side. As a result, the solder 82 is separated into the first electrode side and the second electrode side, the connection between the two electrodes 85 and 86 is released, and the two conductor patterns (circuits) 90 and 91 are separated by the gap 8.
7 is blocked. The concave portion 83 (FIG. 9) slightly bulges outward due to the inflow of the solder 82 on the convex portion 84 side. The end 97 a of the bulging portion 97 comes into contact with the end of the resist film 92 and stops.

The use state of the thermal fuse 88 (FIG. 9) is not limited to the case where the circuit board 80 is vertically (vertically placed). For example, the circuit board 80 may be turned upside down and the concave portion 83 of the solder 82 shown in FIG. Can be used on the lower side and the convex portion 84 on the upper side (not shown).

In this case, since the through hole 81 is located vertically, the molten solder 82 is more likely to flow into the concave portion 83 by its own weight than in the case of FIG. 10, and the circuit is more quickly and reliably shut off. . It goes without saying that the gap 87 between both electrodes is located on the upper convex portion 82 side. In addition,
It is also possible to use the circuit board 80 at an angle. Also in this case, the protrusions 8 of the solder 82 are provided on the upper side of the circuit board 80.
It goes without saying that the gap 87 between the electrode 4 and both electrodes is located.

FIGS. 11 to 12 are sectional views showing a safety device for an electric circuit according to a fifth embodiment of the present invention. The same components as those of the fourth embodiment are denoted by the same reference numerals, and detailed description is omitted.

The safety device 5 is, as in the fourth embodiment shown in FIG.
The thermal fuse 88 is formed by forming a concave portion 83 on the upper side and a convex portion 84 on the lower side. However, the resist film 99 on the surface of the circuit board 98 on the concave portion 83 side is larger than in the fourth embodiment. Retreat the edge 99 of the resist film 99
set to a large distance D ₂ between a, i.e. by largely exposed conductor portion 100 of the component mounting surface side, is characterized in that it has greater outer diameter D ₂ of the land shaped exposed conductor portion 100 . Other configurations are the same as those of the fourth embodiment.

In FIG. 11, the resist film 93 on the solder side below the circuit board 98 is largely separated from the through hole 81 as in the fourth embodiment, and is larger than the end 99a of the upper resist film 99. Slightly retreats in the radial direction. The first electrode 85, the gap 87, and the second electrode 86 are annularly located at the lower portion where the resist film 93 is not provided. Outer diameter D ₂ of the exposed conductor portion 100 of the component mounting surface side compared to the outer diameter D ₃ of the land-shaped second electrode 86 that follows the conductor portion 89 of the through-hole 81 is set larger.

The concave portion 83 of the solder 82 is located in the upper opening 81a of the through hole 81, and the convex portion 84 is formed in the lower opening 8a.
1b, it protrudes greatly (projects) from the solder surface and is in contact with the end 93a of the resist film 93 on the solder surface side. As in the fourth embodiment, the inner diameter of the through hole 81 is
Greater than the thickness T ₂ of the.

In a state where the circuit board 98 is set upright as shown in FIG. 12, when the solder 82 is melted due to an abnormally high temperature, the protrusion 84 of the solder 82 is moved so as to be attracted to the recess 83 in FIG. Is attracted to the exposed conductor portion 100 having a large land shape, and solder 8 is attached to the opening 81 a side of the through hole 81.
2 swells positively. This is because the exposed conductor portion 100 is excellent in the wettability of the solder 82.

In the case of FIG. 10 (fourth embodiment), the solder 82 immediately stops at the resist film 92 following the small-diameter exposed conductor portion 96. However, according to this embodiment, the solder 82 And the connection between the electrodes 85 and 86 is more reliably released. If the used amount of the solder 82 is the same as in the fourth embodiment, the gap 8
It is also possible to bring the position 7 closer to the through hole 81. Further, it is also possible to form the protrusions 84 of the solder 82 sufficiently large so that the two electrodes 85 and 86 can be reliably connected with a large area. Even in this case, the circuit can be quickly and reliably shut off.

The use form of the circuit board 98 may be inverted upside down with respect to FIG. 11, or may be used with an inclination as in the fourth embodiment. In any of these usage forms, the molten solder 82 is positively attracted to the land-shaped exposed conductor portion 100, so that the solder 82
The moving speed of the circuit is increased, and the circuit can be more quickly and surely cut off. However, it cannot be used with the concave portion 83 of FIG. 11 facing upward, and this is the same in the fourth embodiment.

In each of the embodiments shown in FIGS. 9 to 12, the circuit boards 80 and 98 are set horizontally, the molten solder 82 is loaded in the vertical through-hole 81, and the upper part is placed under the own weight of the solder 82. A concave portion 83 and a convex portion 84 are formed on the lower side, and a skirt portion 84b of the convex portion 84 is connected to both electrodes 85 and 86 over a gap 87 between both electrodes. It is also effective as a manufacturing method.

According to this method, the concave portion 83 and the convex portion 84 can be easily and reliably formed by utilizing the own weight of the solder 82, and the solder 8 is attached to the lower (solder surface side) electrodes 85 and 86.
2 can be positively adsorbed to improve the electrical connectivity between the electrodes 85 and 86.

According to the fourth and fifth embodiments of FIGS. 9 to 12, the resist film 40 (FIG. 1) is deteriorated at an abnormally high temperature as compared with the second embodiment of the first to third embodiments. Irrespective of the peeling, the connection between the electrodes 85 and 86 is released when the solder 82 melts and the circuit is cut off, so that the reliability as the thermal fuse 88 is further improved. That is, in the invention described in claim 2,
The resist film 40 (FIG. 1) is peeled off, and the solder 34 is sucked between the resist film 40 and the conductor portion 31 (FIG. 1) of the circuit board 10, whereby the solder 3 to both electrodes 31a and 32a is formed.
According to the fourth and fifth embodiments, the solder 82 is sucked into the through-hole 81 at the same time as the solder 82 is melted, without waiting for the peeling of the resist film 93. The connection between the electrodes 85 and 86 is released.

[0113]

As described above, according to the electric circuit safety device of the present invention, when the overcurrent protection element, which is the first protection means, is abnormally overheated, the thermal fuse, which is the second protection means, ensures the protection. In addition, it is possible to prevent accidents, and to operate the thermal fuse quickly when the overcurrent protection element is abnormally heated. On the other hand, according to the method for manufacturing a safety device for an electric circuit of the present invention, the thermal fuse can be easily formed by an automatic soldering device or the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a safety device for an electric circuit according to a first embodiment of the present invention.

FIGS. 2A and 2B show a safety device for the electric circuit, wherein FIG. 2A is a front view and FIG. 2B is a rear view.

FIG. 3 is a sectional view of only a circuit board constituting the safety device for the electric circuit.

FIGS. 4A and 4B show only the circuit board, and FIG. 4A is a front view and FIG. 4B is a rear view.

5 (a), 5 (b) and 5 (c) are front views showing operating states of a thermal fuse constituting a safety device of the electric circuit.

FIG. 6 is a sectional view showing a safety device for an electric circuit according to a second embodiment of the present invention.

FIG. 7 is an explanatory view showing a conductor pattern of a thermal fuse in the safety device for an electric circuit.

FIG. 8 is a sectional view showing a safety device for an electric circuit according to a third embodiment of the present invention.

FIG. 9 is a sectional view showing a safety device for an electric circuit according to a fourth embodiment of the present invention.

FIG. 10 is a sectional view showing an operation state of a thermal fuse constituting the safety device for the electric circuit.

FIG. 11 is a sectional view showing a safety device for an electric circuit according to a fifth embodiment of the present invention.

FIG. 12 is a sectional view showing an operation state of a thermal fuse constituting the safety device for the electric circuit.

FIG. 13 is an external view showing a conventional safety device for an electric circuit using a PTC element.

FIGS. 14 (a), (b) and (c) are explanatory diagrams showing the configuration and operation of a safety device for an electric circuit using a conventional voltage-dependent varistor.

FIGS. 15A, 15B, and 15C are explanatory diagrams showing the configuration and operation of a conventional thermal fuse.

[Explanation of symbols]

1, 2, 3, 4, 5 Safety device for electric circuit 10, 80, 98 Circuit board 10A Front surface (one surface) 10B Back surface (other surface) 11 holes 20 PTC element (overcurrent protection element) 21, 61 Lead 30, 50 , 70, 88 Thermal fuse 31, 51, 71, 90 One conductor pattern 31a, 51a, 71a, 85 First electrode 32, 52, 72, 91 Other conductor pattern 32a, 52a, 72a, 86 Second electrode 32b, 81 Through hole 33, 53, 73, 87 Gap 34, 54, 74, 82 Solder 40, 92, 93, 99 Resist film 60 Electrical component 83 Recess 84 Convex 100 Exposed conductor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02H 5/04 H02H 5/04 D 9/02 9/02 B (72) Inventor Naofumi Maruo Haibara-gun, Shizuoka 206-1 Nunobikibara, Haibara-cho Yazaki Parts Co., Ltd. F-term (reference) 5G004 AA01 AB02 BA04 DA02 5G013 AA09 BA01 CA02 5G502 AA01 AA02 BB13 CC04 CC28 EE05 EE08 JJ01

Claims (15)

[Claims] 1. A first protection means for protecting an electric circuit from overcurrent, wherein the overcurrent protection generates heat when an overcurrent flows through the electric circuit to increase resistance and reduce or cut off the overcurrent. An element, a second protection means provided near the overcurrent protection element, wherein the first electrode of one conductor pattern connected to the overcurrent protection element is insulated by a gap from the first electrode. The second electrode of the other conductor pattern, the first and second electrodes are bridged, melted by the heat from the overcurrent protection element, and the temperature of the solder separated to the first and second electrode sides. A safety device for an electric circuit, comprising a fuse. 2. The heat from the overcurrent protection element,
2. The safety device for an electric circuit according to claim 1, wherein the resist film around the thermal fuse is peeled off. 3. When the circuit board on which the overcurrent protection element and the thermal fuse are mounted is installed vertically, the thermal fuse is substantially the same as the overcurrent protection element or above the overcurrent protection element. Claim 1 which is located
Or the safety device for an electric circuit according to 2. 4. A hole is formed in a gap between the first and second electrodes forming the thermal fuse, a lead of an electric component is inserted through the hole, and the first and second electrodes are inserted together with the lead. The safety device for an electric circuit according to any one of claims 1 to 3, wherein the device is bridged with solder. 5. The safety device for an electric circuit according to claim 4, wherein the electric component is the overcurrent protection element. 6. A land in which the other conductor pattern forming the thermal fuse is formed on one surface of the circuit board, and the other conductor pattern is formed on the other surface of the circuit board via a through hole. The second electrode is continuous with the second electrode, and on the other surface of the circuit board, the second electrode is surrounded by the first electrode without any gap, and the first and second electrodes are bridged with solder. The safety device for an electric circuit according to claim 1. 7. The second electrode forming the thermal fuse is formed in a land shape formed on the periphery of a hole for inserting a lead of an electric component, and the second electrode is formed with a gap by the first electrode. The safety device for an electric circuit according to any one of claims 1 to 3, wherein the first and second electrodes are bridged with solder together with the leads of the electric component that are surrounded without interruption and inserted into the holes. 8. The first electrode forming the thermal fuse has a land shape formed on the periphery of a hole for inserting a lead of the overcurrent protection element, and the first electrode is formed by a gap by the second electrode. The safety device for an electric circuit according to any one of claims 1 to 3, wherein the first and second electrodes are bridged with solder, with the leads of the overcurrent protection element inserted into the holes without being interrupted. . 9. The safety device for an electric circuit according to claim 1, wherein the overcurrent protection element is a PTC element. 10. The method for manufacturing a safety device for an electric circuit according to claim 4, wherein the device for automatically soldering an electric component on the circuit board including the overcurrent protection element comprises: A method for manufacturing a safety device for an electric circuit, wherein the first and second electrodes are bridged with solder at the same time as the soldering of the electric components, thereby forming the thermal fuse. 11. A solder is loaded in a through hole of a circuit board, the solder having a concave portion on one opening side of the through hole and a convex portion on the other opening side, wherein the convex portion is the first electrode. 2. A bridge between the first electrode and the second electrode.
Safety device for the described electrical circuit. 12. The safety device for an electric circuit according to claim 11, wherein an inner diameter of the through hole is set larger than a thickness of the circuit board. 13. The circuit according to claim 11, wherein the outer diameter of the exposed conductor portion of the circuit board on the concave side is set to be at least larger than the outer diameter of the second electrode near the through hole. Safety device for electric circuit. 14. The safety device for an electric circuit according to claim 11, wherein the circuit board is arranged vertically, or the circuit board is arranged with the convex portion facing upward. 15. The method for manufacturing a safety device for an electric circuit according to claim 11, wherein the circuit board is positioned horizontally, and molten solder is loaded into the through holes in a vertical direction. A method for manufacturing a safety device for an electric circuit, wherein the concave portion and the convex portion are formed by the weight of the solder.