JP2000323308A - Surface mounting device and its mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mounting device wherein a device element like fusible alloy is accommodated in an insulating case, terminal parts are arranged on the back, and the inner device element is not damaged by infrared ray irradiation when mounting is performed via an infrared ray furnace, i.e., a mounting method is not restricted. SOLUTION: Electrodes 2, 3 are arranged on the surface of an insulating board 1 formed in a black system color, terminal parts 4, 5 connected with the electrodes 2, 3 are arranged on the back, fusible alloy 6 which is to be fused at a specified temperature is connected and fixed to both inside ends of the electrodes 2, 3, as a device element, the fusible alloy 6 is covered with flux 7, and the surface side of the insulating board 1 is covered and sealed with an insulating cap 8 formed in a white system color. Since the insulating cap 8 is formed in the white system color, heat absorption of the insulating cap is small when a mounting method passing an infrared ray furnace is adopted, and the fusible alloy 6 as the device element is not fused erroneously, so that a mounting method is not restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount device, and more particularly, to a surface mount device in which a device element containing a fusible material which is adversely affected by heating and which melts at a specific temperature, for example, is accommodated in an insulating case. Type device. The present invention also relates to a method of mounting a surface-mounted device, and more particularly, to a surface-mounted device including a device element containing a fusible material that is adversely affected by heating and that melts at a specific temperature, for example, in an insulating case. The present invention relates to a mounting method for mounting on a mounting body such as a printed circuit board.

[0002]

2. Description of the Related Art Recently, protection elements have been used to protect electronic devices and household goods from fire caused by overheating of electronic devices. As this type of protection element, there is a thermal fuse using a temperature-sensitive material that melts at a specific temperature. The thermal fuse is roughly classified into a thermal sensitive pellet type and a fusible alloy type according to the type of the temperature sensitive material. The former uses, as a temperature-sensitive material, a temperature-sensitive pellet made of an insulating chemical substance that melts at a specific temperature, and the movable contact is pressed against the fixed contact by holding the predetermined shape of the temperature-sensitive pellet. Electric current is supplied through the movable contact and the fixed contact, and the melting of the thermosensitive pellet causes the movable contact to separate from the fixed contact, thereby opening the circuit. On the other hand, the latter fusible alloy type uses a fusible alloy that melts at a specific temperature as a temperature-sensitive material, energizes through the fusible alloy, and opens the circuit by melting the fusible alloy. Things. Further, in addition to the above-mentioned thermal fuse, a fusible alloy that melts at a specific temperature and a resistor for heating the fusible alloy are provided, and the fusible alloy is forcibly blown by the heat generated by energizing the resistor. There is a composite type protection element that opens a circuit by opening the circuit. As these protection elements, those having leads are generally used. On the other hand, surface mounting of electronic components has been progressing, and surface protection type protection elements have been developed. About such surface mount type protection element,
This will be described below with reference to the drawings.

FIG. 15 is a longitudinal sectional view of a conventional surface mount type protection element, and FIG. 16 is a plan view showing the internal structure of the surface mount type protection element by removing an insulating cap and a flux. In FIG. 15 and FIG.
Is a rectangular insulating substrate made of a ceramic such as alumina, and has a pair of electrodes 72 and 73 formed by applying and baking silver paste or the like on both ends in the longitudinal direction of one surface thereof. The pair of electrodes 72 and 73 are connected to a pair of terminal portions 74 and 75 formed on the back surface through the end surface of the insulating substrate 71. A fusible alloy 76, which melts at a specific temperature, is connected and fixed between the inner ends of the electrodes 72, 73 on the front surface.
7. Then, the pair of electrodes 72, 7
The flux 3 and the flux 77 are covered and sealed with an insulating cap 78 made of a molding resin or the like. Here, the insulating substrate 71 is generally of a white system color, while the insulating cap 8 is generally formed of a black system color, and the type name, rating, manufacturer's mark, etc. are stamped on the surface with white ink. Is displayed.

Next, an example of a mounting method of the protection element will be described. FIG. 17 shows a method of mounting the above-described protection element. That is, in FIG. 17, reference numeral 79 denotes an attachment body such as a printed board on which the protection element is mounted, and has terminal sections 80 and 81 made of copper or the like for fixing the terminal sections 74 and 75 on the back surface of the protection element. Although not shown,
Solder is previously applied to the terminals 74 and 75 of the protection element and / or the terminals 80 and 81 of the mounting body 79 by plating or other methods. And the terminal 7 of the protection element.
4, 75 are aligned with the terminal portions 80, 81 of the mounting body 79, and a hot air reflow furnace, an N2 reflow furnace, a VPS (Vapo
r Phase Soldering) Pass through a furnace etc.
5 and / or the solder applied to the terminal portions 80 and 81 of the mounting body 79 is heated and melted at about 230 to 240 ° C. so that the terminal portions 74 and 75 of the protection element are connected to the terminal portions 80 and 81 of the mounting body 79. 81 is fixedly connected. Among the above various mounting methods, the infrared reflow furnace is radiant heating by infrared rays, so it has excellent features such as rapid temperature rise and good heating efficiency, and may be adopted as a mounting method for electronic components. Many.

However, in the conventional protection element, since the insulating cap 78 is formed in a black color, the insulating cap 78 is mounted through an infrared reflow furnace that irradiates infrared rays 82 from above the insulating cap 78 as described above. Cap 7
8, there is a problem that the fusible alloy 76 inside is liable to be erroneously melted due to the large infrared absorption.

Therefore, in order to prevent erroneous melting of the fusible alloy 76, it is conceivable to set the melting point of the fusible alloy 76 to a high melting point of 300 ° C. or higher with respect to a reflow temperature of about 230 to 240 ° C. However, in such a method,
Since the operating temperature of the protection element itself changes, the original function of the protection element, which protects electronic devices and the like by fusing at a predetermined temperature, is impaired, and the device falls over. In addition, in a composite protection element provided with a resistor that forcibly blows this fusible alloy by energizing heat generation in addition to the fusible alloy, if the melting point of the fusible alloy is increased as described above, Since the fusible alloy is forcibly blown by the heat generated by the current flowing through the body, changing the melting point of the fusible alloy itself does not cause the above-mentioned problem of the thermal fuse, but the fusible alloy is blown from the start of energization to the resistor. However, there is a problem in that the time required to perform the operation is long, and the function as a protection element is deteriorated. further,
If the resistance value of the resistor is reduced in order to shorten the time required to melt the fusible alloy, there is a problem that power consumption increases.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a device for mounting a surface mounted device having a device element which is affected by heating of a fusible alloy or the like by an infrared ray reflow method using infrared irradiation. It is an object of the present invention to provide a surface mount device in which device elements are not adversely affected, that is, the mounting method is not limited. In addition, the present invention does not adversely affect the internal device elements even when a surface-mounted device having device elements that are affected by heating of a fusible alloy or the like is mounted by an infrared reflow method using infrared irradiation. That is, an object of the present invention is to provide a surface mounting method in which a mounting method is not limited.

[0008]

According to the present invention, there is provided a surface mount type device comprising: an insulating case; a device element housed in the insulating case; and a terminal formed on a lower surface of the insulating case. The surface mounting type device is characterized in that the color of the upper part of the insulating case is white. Further, the mounting method of the surface-mounted device of the present invention includes the step of mounting the surface-mounted device having an insulating case, a device element housed in the insulating case, and a terminal portion formed on the lower surface of the insulating case. A method of mounting on a terminal portion, wherein solder is interposed between a terminal portion on a lower surface of the surface-mounted device and a terminal portion of a mounting body to align them, and the surface is mounted by irradiating infrared rays. This is a method for mounting a surface mount device.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION
In a surface mount device having an insulating case made of an insulating substrate and an insulating cap, a device element housed in the insulating case, and a terminal formed on the lower surface of the insulating case, the color of the insulating cap is changed to white. This is a surface-mounted device characterized by the following.

According to a second aspect of the present invention, the device mounted in the insulating case contains a fusible alloy which melts at a specific temperature. Type device.

According to a third aspect of the present invention, the device element accommodated in the insulating case includes a fusible alloy that melts at a specific temperature and a resistor that melts the fusible alloy by heat generated by energization. 2. The method according to claim 1, wherein
20 is a surface-mounted device as described.

According to a fourth aspect of the present invention, as a device element housed in the insulating case, a fusible alloy that melts at a specific temperature and a plurality of resistors that melt the fusible alloy by heat generated by energization are provided. The surface mount device according to claim 1, further comprising:

[0013] The invention according to claim 5 of the present invention is the surface mount type device according to claims 1 to 4, wherein the fusible alloy has a melting point of 250 to 300 ° C.

According to a sixth aspect of the present invention, in the surface mount device according to any one of the first to fifth aspects, the color of the insulating cap is white, and the color of the insulating substrate is dark. is there.

The invention according to claim 7 of the present invention is characterized in that the color of the insulating cap has a lightness of 7 or more and / or a saturation of 0 to 2 in a color solid diagram.
7. A surface-mounted device according to any one of items 6 to 6.

[0018] The invention according to claim 8 of the present invention is directed to an insulating case in which the color of the insulating cap is formed in a white system, a device element housed in the insulating case, and a terminal formed on the lower surface of the insulating case. A method of mounting a surface-mounted device having a terminal portion of a mounting body, comprising: interposing a solder between a terminal portion on a lower surface of the surface-mounting device and a terminal portion of the mounting body to form the two terminal portions. This is a method for mounting a surface-mounted device, characterized in that the surface is mounted by irradiating infrared rays after alignment.

According to a ninth aspect of the present invention, there is provided an insulating case in which the color of an insulating cap is formed in a white system, a device element housed in the insulating case, and a terminal formed on a lower surface of the insulating case. A method of mounting a surface-mounted device having a terminal portion of a mounting body, comprising: forming a solder layer on a terminal portion on a lower surface of the surface-mounting device and / or a terminal portion of the mounting body; Align,
This is a method for mounting a surface mounting device, which is characterized in that the surface mounting is performed by irradiating infrared rays.

According to a tenth aspect of the present invention, there is provided an insulating case comprising an insulating substrate formed in a dark color and an insulating cap formed in a white color, and a device element accommodated in the insulating case. A method of mounting a surface-mounted device having a terminal portion formed on a lower surface of an insulating case on a terminal portion of a mounting body, wherein the terminal portion on the lower surface and the terminal portion of the mounting body in the surface-mounted device. A method for mounting a surface-mounted device, characterized in that the two terminal portions are aligned with a solder interposed therebetween and surface-mounted in an infrared reflow furnace.

The invention according to claim 11 of the present invention is characterized in that the color of the insulating cap has a lightness of 7 or more and / or a saturation of 0 to 2 in a color solid diagram. It is a mounting method of the surface mounting device described.

[0020]

Embodiments of the present invention will be described below. FIG. 1 is a longitudinal sectional view of a surface mount device A of a first embodiment in which the present invention is applied to a protection element, and FIG. 2 shows a state before the flux application in the surface mount device A of FIG. It is the top view of the state which removed and made the internal structure visible. 1 and 2
Wherein 1 is a trade name such as black ceramic obtained by mixing a black colored filler into a ceramic green sheet of alumina or the like and sintered, polybutylene terephthalate (PBT) containing a black colored filler, liquid crystal polymer, 46 nylon or 66 nylon A pair of electrodes formed by applying and baking a conductive material such as a silver paste or a silver palladium paste on both ends in the longitudinal direction of one surface of a rectangular and black insulating substrate made of a molding resin such as polyamide known as It has a few. The pair of electrodes 2 and 3 are formed so as to extend to the back surface through the end surface of the insulating substrate 1, and are formed by applying and firing a conductive material such as a silver paste or a silver palladium paste on the back surface. The terminals 4 and 5 are connected. The terminal portions 4 and 5 may be made of silver or silver palladium which is a conductive material, or a conductive layer having good solderability such as a silver layer or a gold layer may be formed thereon. A specific temperature, for example, 250-300, between the inner ends of the electrodes 2 and 3 on the surface.
A fusible alloy 6 which melts at a temperature of 0 ° C. is connected and fixed, and this fusible alloy 6 is covered with a flux 7. The pair of electrodes 2 and 3 and the flux 7 are covered and sealed with an insulating cap 8 made of molding resin such as white alumina ceramic or white polybutylene terephthalate (PBT) or liquid crystal polymer. Here, the insulating cap 8 is formed in a white color as described above, and the type name, rating, manufacturer's mark, and the like are stamped and marked on the surface with black-based ink.

Next, an example of a mounting method of the surface mount device A of the first embodiment will be described. FIG. 3 shows a mounting method of the above-mentioned surface mount device A. That is, in FIG. 3, reference numeral 9 denotes an attachment body such as a printed circuit board on which the surface mount device A is mounted, and copper, nickel, and the like for fixing the terminal portions 4 and 5 on the back surface of the surface mount device A.
Terminal part 1 made of conductive material having good solderability such as silver or gold
0 and 11 are provided. And the surface mount device A
The terminal portions 4 and 5 of the mounting body 9 are aligned with the terminal portions 10 and 11 with solder therebetween, and infrared rays are irradiated from above the surface mount device A at a set temperature of 230 to 240 ° C. Through which the solder interposed between the terminal portions 4 and 5 and the terminal portions 10 and 11 of the mounting body 9 is heated and melted so that the terminal portions 4 and 5 of the surface mount device A are connected to the terminal portions 10 and 11 of the mounting body 9. 11 is fixedly connected. here,
As solder to be interposed between the terminal portions 4 and 5 of the surface mount device A and the terminal portions 10 and 11 of the mounting body 9, a solder different from the surface mounting device A and the mounting body 9 may be inserted at the time of mounting. Immediately before mounting, for example, the terminal portions 10, 1 of the mounting body 9
1, a solder layer may be applied to the terminals 4 and 5 of the surface mount device A and / or the terminals 10 and 11 of the mounting body 9 in advance by plating or other method. It is desirable to wear it.

In the surface mount device A according to the first embodiment of the present invention, since the insulating cap 8 is formed in a white color, the infrared reflow furnace for irradiating infrared rays from above the insulating cap 8 as described above is used. Even if the mounting method in which the furnace is passed is adopted, since the heat absorption of the insulating cap 8 is small, there is a feature that the fusible alloy 6 inside is not heated and erroneously melted. When the insulating substrate 1 is formed in a black color as in the above-described embodiment, the heat absorption of the insulating substrate 1 increases, and the terminal portions 4 formed on the back surface of the surface mount device A are formed. 5 and / or the solder layer pre-applied to the terminal portions 10 and 11 of the mounting body 9 is effectively heated and can be mounted in a short time, so that the fusible alloy 6 is heated through the insulating cap 8 accordingly. It also has the advantage that erroneous melting due to heat is reduced.

Next, a second embodiment of the present invention is applied to a composite type protection element including a fusible alloy and a resistor for forcibly blowing the fusible alloy by energization and heat generation. The device B will be described. FIG. 4 is a longitudinal sectional view along the central axis in the longitudinal direction of the surface mount device B, and FIG. 5 is a longitudinal sectional view along the central axis in the lateral direction. 6 to 11
FIG. 9 is a plan view or a bottom view of an insulating substrate and the like along a manufacturing process of the surface mount device B of the second embodiment. FIG.
FIG. 4 is a bottom view of the insulating cap.

A description will be given below with reference to FIGS. First, reference numeral 21 denotes an insulating substrate of a black color obtained by mixing a black coloring filler into a green sheet of alumina ceramic or the like and sintering the same, as shown in FIG. , 23, and has convex portions 24, 25, 26, 27 on both sides at both ends in the longitudinal direction. A concave portion 28 is formed between the convex portions 22, 24, and convex portions 23, 2
5, a concave portion 30 between the convex portions 22 and 26, and a concave portion 31 between the convex portions 23 and 27.

As shown in FIG. 7, an electrode formed by applying and firing a conductive material such as a silver paste or a silver-palladium paste is applied to the convex portions 22 to 27 and the vicinity thereof on the surface of the insulating substrate 21. 32 to 37.
A "T-shaped" connection conductor 38 connecting between the electrodes 34 and 35 is formed, and a "T-shaped" connection conductor 38 connecting between the electrodes 36 and 37 is formed between the electrodes 36 and 37. 39 are formed. In addition, both "T-shaped"
An “I-shaped” relay conductor 40 is formed between the connection conductors 38 and 39 of the first embodiment so as to be separated from the connection conductors 38 and 39. The connection conductors 38 and 39 and the relay conductor 40 are:
Using the same conductive material as each of the electrodes 32 to 37,
In addition, it is formed by coating and firing at the same time.

As shown in FIG. 8, terminals formed by applying and baking a conductive material such as a silver paste or a silver-palladium paste are applied to the convex portions 22 to 27 on the back surface of the insulating substrate 21 and the vicinity thereof. It has parts 41 to 46. These terminal portions 41 to 46 are connected to the respective electrodes 32 to 37 on the front surface through the end surfaces of the respective convex portions 22 to 27 of the insulating substrate 21, as is apparent from FIG. That is, the terminal 41 is the electrode 32, the terminal 42 is the electrode 33, the terminal 43 is the electrode 34, the terminal 44 is the electrode 35, the terminal 45 is the electrode 36, the terminal 46 is the electrode 37, Each is connected. The terminal portions 43 and 4
4, an "I-shaped" connection conductor 47 connecting the two is provided.
Are formed, and an "I-shaped" connection conductor 48 connecting between the terminal portions 45 and 46 is formed. Further, an "I-shaped" connection conductor 49 for connecting the two connection conductors 47, 48 is formed between the two "I-shaped" connection conductors 47, 48. Each of the connection conductors 47, 4
8, 49 are formed by using the same conductive material as the electrodes 41 to 46 and simultaneously applying and firing.

As shown in FIG. 9, between the connecting conductors 38 and 40 on the surface of the insulating substrate 21 and between the connecting conductors 40 and 39, for example, resistor fine particles such as ruthenium oxide are mixed in a glass paste. Resistors 50 and 51 are formed by applying and firing the resist paste thus formed. In FIG. 9, for reference, the central axis X in the longitudinal direction of the insulating substrate 21 at the cutting position in the longitudinal sectional view shown in FIG.
5 and the center axis Y in the lateral direction of the insulating substrate 21 at the cutting position in the longitudinal sectional view shown in FIG. 5 and the arrow direction BB looking at the cross section. It is shown.

Further, as shown in FIG.
An insulating layer 52 is formed by coating and baking a glass paste or the like so as to cover the connection conductors 47, 48 and 49 on the back surface. The insulating layer 52 is formed of the connection conductor 4
Reference numerals 7, 48, and 49 are for preventing a short circuit or insulation withstand voltage failure from occurring with other terminal portions or wiring layers of the mounting body 9, or mounted components. If necessary, an insulating layer such as a black epoxy resin may be laminated on the insulating layer 52. The black insulating layer prevents a reduction in commercial value due to the internal connection conductors 47 to 49 being visible through the transparent insulating layer 52.

Further, as shown in FIG.
Solder layers 54 to 59 are applied to the upper surface (lower surface) of each of the terminal portions 41 to 46 on the back surface of the mounting member 1 for surface mounting on the terminal portions of the mounting body described later. This solder layer 54
4 and 5, the lower surfaces of the insulating layers 52 project from the lower surfaces of the insulating layers 52 covering the connection conductors 49. The solder layer for surface mounting may be formed not only on the terminal portions 41 to 46 of the surface mounting device B, but also on the terminal portions of the mounting body.
It may be formed on both the terminal portions 41 to 46 of the surface mount device B and the terminal portion of the mounting body. Alternatively, a solder paste may be applied to the terminal portion of the mounting body immediately before mounting.

Further, as shown in FIG. 9, a fusible alloy 53 that melts at a specific temperature is fixedly connected between the electrodes 32 and 33 on the surface of the insulating substrate 21. As is clear from FIGS. 4 and 5, it is covered with the flux 60.

On the surface side of the insulating substrate 21, an insulating cap 61 made of a white resin such as alumina ceramic of white color or polybutyl terephthalate (PBT) or a liquid crystal polymer is covered, and an adhesive 62 is formed. Is fixedly sealed to the insulating substrate 21. This insulating cap 6
As shown in FIG. 12, 1 is a wall 61
a and recesses 61b, 61b at locations corresponding to the electrodes 32, 33. These recesses 61b, 6
1b is for receiving the above-mentioned fusible alloy 53 and the flux 60 deposited thereon.

Also in the surface mount type device B of the second embodiment of the present invention, the insulating substrate 21 is formed in a dark color (black) and the insulating cap 61 is formed in a white color (white). As described above, even when mounting is performed through an infrared reflow furnace during surface mounting, the heat absorption of the insulating cap 61 is small and the heat absorption of the insulating substrate 21 is large, so that the internal fusible alloy 53 is erroneously melted. Surface mounting can be performed without the need for mounting, that is, there is a feature that the mounting method is not limited. As described above, when an insulating layer made of black epoxy resin or the like is formed on the insulating layer 52 covering the connection conductors 47 to 49 formed on the back surface of the insulating substrate 21, the black insulating layer There is a feature that surface mounting can be performed in a shorter time by heat absorption.

Incidentally, as shown in the second embodiment, the projections 22 to 27 are provided on the insulating substrate 21 so that each of the projections 22 to 27 is provided.
If the electrodes 32 to 37 and the terminal portions 41 to 46 are formed on the electrodes 27 to 27, adjacent electrodes and / or terminal portions are partitioned by the concave portions 28 to 31,
There is also a feature that a short circuit between adjacent electrodes and / or terminal portions can be reliably prevented.

FIG. 13 is an equivalent circuit diagram of the surface mount device B of the second embodiment. That is, in the surface-mounted device B of the second embodiment, the electrodes 32, 33 on the center surface in the longitudinal direction of the insulating substrate 21 are connected to the terminal portions 41, 42 on the back surface, respectively, and have the same potential. . Therefore, in FIG. 13, 32 (41), 33 (4
It is written as 2). The electrodes 34, 35 at one end in the longitudinal direction of the insulating substrate 21 are connected to terminal portions 43, 44 on the back surface, respectively.
It is described as (44). Further, the insulating substrate 21
The electrodes 36 and 37 at the other end in the longitudinal direction are connected to the terminal portions 45 and 46 on the back surface, respectively.
37 (46). And, between the electrodes 32 and 33 at the central part in the longitudinal direction of the insulating substrate 21,
As shown in FIG. 9, the fusible alloy 53 is connected,
Under the central part of the fusible alloy 53 in the longitudinal direction, the “I-shaped” relay conductor 40 traverses, so as shown in FIG. 13, there is a gap between the electrodes 32 (41) and 33 (42). This means that the two thermal fuses TF1 and TF2 are connected in series. Further, as shown in FIG. 9, a “T-shaped” connection conductor 38 connected to the electrodes 34 and 35 and the “I-shaped”
Is formed between the electrodes 34 (43) and 35 (44) and the two thermal fuses TF1 and TF2 connected in series.
, A resistor R50 is connected. Similarly, FIG.
As shown in the figure, "T-shaped" connected to the electrodes 36 and 37
Since the resistor 51 is formed between the connection conductor 39 and the "I-shaped" relay conductor 40, the electrode 36 (4
5), 37 (46) and the connection point a of the two series-connected thermal fuses TF1 and TF2.
Is connected. Further, as shown in FIGS. 8, 10 and 11, an electrode 34 at one end in the longitudinal direction of the insulating substrate 21 is provided.
(43), 35 (44) and the other end electrode 36 (45),
37 (46) are connected by connection conductors 47, 48, 49, and therefore, as shown in FIG.
(43), 35 (44) and 36 (45), 37 (46)
Is short-circuited by the short-circuit line 63.

FIG. 14 is an equivalent circuit diagram obtained by further simplifying the equivalent circuit diagram of FIG. That is, as described above, the electrodes 34 (4
3), 35 (44), 36 (45), and 37 (46) are all connected. Therefore, for simplicity, the terminal portions 41 and 42 are described with reference to the terminal portions 41 to 46 on the back surface.
Two thermal fuses TF1 and TF2 are connected in series between the two thermal fuses TF1 and TF2, and the two thermal fuses TF1 and TF2 are connected between the connection point a and the terminal portions 43 (45) and 44 (46). This means that the resistors R50 and R51 are connected in parallel. Now, assuming that the resistance values of these two resistors R50 and R51 are R50 and R51, respectively, the resistance value R0 of the parallel equivalent resistance R can be expressed by the following equation. R0 = (R50 · R51) / (R50 + R51)

As is clear from the equivalent circuit diagram of FIG. 14, the surface mount device B according to the second embodiment of the present invention comprises:
It has two thermal fuses TF1 and TF2 and one equivalent resistance R. Further, not only is there no directionality in the longitudinal direction of the insulating substrate 21, but also there is no directionality in the short direction of the insulating substrate 21. For this reason,
In mounting this surface mount type device B, there is a feature that it is not necessary to consider the directionality at all, and it is possible to assemble in any direction.

Next, an example of using the surface mount device B of the second embodiment will be described. In the above surface mount device B, the fusible alloy 53 (that is, the two thermal fuses TF1 and TF2) is connected to an electronic device (not shown) or the like by using the terminal portions 41 and 42 so as to conduct electricity. Keep it. In addition, the resistors 50 and 51 (that is,
Equivalent resistance R) is applied to the terminal 43 (45) or 44 (46).
Is connected to a power supply via a switching element (not shown) that is turned on by a detection operation of a detection element such as temperature, voltage, current, or the like. Then, if the temperature, voltage, current, and the like of the detection target are within the predetermined normal ranges, the detection element does not perform the detection operation, and thus the switching element remains in the non-conductive state.
Since the resistors 50 and 51 (equivalent resistance R) are not energized, and therefore the fusible alloy 53 is not heated, the fusible alloy 53 (ie, the temperature fuses TF1 and TF2) is continuously supplied to the electronic device. It is energized. However,
When the temperature, voltage, current, or the like of the detection target is in an abnormal state that exceeds a normal range set in advance, the detection element detects the abnormality and makes the switching element conductive, and the resistors 50 and 5 are turned off.
1 (equivalent resistance R) is energized. This resistor 50,
When the current flows through the resistor 51, the resistors 50 and 51 start generating heat, and the generated heat is transmitted to the fusible alloy 53 through the insulating substrate 21 and / or the rod-shaped connection conductor 40, and the fusible alloy 53 is melted. Therefore, the power supply to the electronic device is cut off. Here, as shown in FIG.
1 and the fusible alloy 53 is located between
Since the fusible alloy 53 is heated from the resistors 50 and 51 on both sides by the start of energization at 0 and 51, the fusible alloy 53 not only melts in a short time but also attaches the surface mount device B. Irrespective of the direction, since the fusible alloy 53 is reliably blown by one of the resistors 50 and 51, there is a feature that the protection function at the time of abnormality is improved.

In the first and second embodiments, the case where the present invention is applied to a protective element having a specific structure has been described. However, various modifications can be made without departing from the spirit of the present invention. Needless to say.

For example, in each of the above embodiments, the case where the insulating caps 8 and 61 are formed in a white color and the insulating substrates 1 and 21 are formed in a black color has been described. , 21 may be other colors.

In the present invention, the white-based color means
Although white is the most preferable, it is not limited to strictly white but also includes a color having a small infrared absorption such as cream or yellow. Such materials include
For example, a liquid crystal polymer that exhibits yellow as a natural color can be used. The white system color in the present invention refers to, for example, a range in which the lightness is about 7 or more and / or the saturation is about 0 to 2 in terms of lightness and saturation in a color solid diagram.

Further, in the present invention, the color of the dark system refers not only to strict black but also to a black system such as gray and a dark color such as dark green and dark blue which has a large infrared absorption. Incidentally, the color of the dark system in the present invention,
For example, in terms of lightness and saturation in a color three-dimensional diagram, the lightness is about 1 to 5 or the saturation is 0 or more.

[0042]

As described above, the present invention provides a surface mount having an insulating case comprising an insulating substrate and an insulating cap, a device element housed in the insulating case, and a terminal formed on the lower surface of the insulating case. In the type device, since it is a surface mounting type device characterized in that the color of the insulating cap is a white system, even if a mounting method of passing through an infrared reflow furnace that irradiates infrared light from above the surface mounting device is adopted, Since the amount of heat absorbed into the inside through the insulating cap is small, the device elements housed therein are not adversely affected by the heat, and a surface mounting type device without any limitation in mounting method can be provided. The present invention also provides
Terminals on the lower surface of a surface mount device having an insulating case in which the color of the insulating cap is formed in a white system, device elements housed in the insulating case, and terminals formed on the lower surface of the insulating case, and / or A method for mounting a surface-mounted device, comprising forming a solder layer on a terminal portion of a mounting body to which the surface-mounted device is to be assembled, aligning the two terminal portions, and irradiating infrared rays to perform surface mounting. Therefore, even when irradiating infrared light, the amount of heat received by the internal device element through the insulating cap is small, so that the device element is not adversely affected by the infrared irradiation, enabling surface mounting by infrared irradiation which could not be adopted conventionally. A method for mounting a surface mount device can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a surface mount device A according to a first embodiment of the present invention.

FIG. 2 is a plan view of the surface mount device A according to the first embodiment of the present invention before flux application, that is, a state in which the insulating cap and the flux are removed so that the internal structure is visible.

FIG. 3 shows a surface mount device A according to a first embodiment of the present invention.
Front view explaining how to mount

FIG. 4 is a longitudinal sectional view of a surface mount device B according to a second embodiment of the present invention along a central axis in a longitudinal direction.

FIG. 5 is a longitudinal sectional view of a surface-mounted device B according to a second embodiment of the present invention, taken along the central axis in the lateral direction.

FIG. 6 is a plan view of an insulating substrate of a surface mount device B according to a second embodiment of the present invention.

FIG. 7 is a plan view showing a surface-mounted device B according to a second embodiment of the present invention in which electrodes and connection conductors are formed on the surface of an insulating substrate.

FIG. 8 is a bottom view of the surface mounting device B according to the second embodiment of the present invention in which terminals and connection conductors are formed on the back surface of the insulating substrate.

FIG. 9 is a plan view of a surface mount device B according to a second embodiment of the present invention in which a resistor and a fusible alloy are formed on electrodes and connection conductors formed on the surface of an insulating substrate.

FIG. 10 shows a surface mount device B according to a second embodiment of the present invention.
Bottom view with insulating layer formed on connection conductors formed on the back side of insulating substrate

FIG. 11 shows a surface mount device B according to a second embodiment of the present invention.
Bottom view with solder layer formed on the terminal part formed on the back surface of the insulating substrate of FIG.

FIG. 12 shows a surface mount device B according to a second embodiment of the present invention.
Bottom view of insulation cap

FIG. 13 shows a surface mount device B according to a second embodiment of the present invention.
Equivalent circuit diagram

FIG. 14 shows a surface mount device B according to a second embodiment of the present invention.
Simplified equivalent circuit diagram of

FIG. 15 is a longitudinal sectional view of a conventional surface mount type protection element taken along a central axis in a longitudinal direction.

FIG. 16 is a plan view of a conventional surface mount type protection element with an insulating cap and a flux removed.

FIG. 17 is a front view for explaining a mounting method of a conventional surface mount protection element.

[Explanation of symbols]

1, 21 Insulating substrate 2, 3, 32, 33, 34, 35, 36, 37 Electrode 4, 5, 41, 42, 43, 44, 45, 46 Terminal section 6, 53 Fusing alloy 7, Reference Signs List 60 Flux 8, 61 Insulating cap 9 Attachment body 10, 11 Terminal part 38, 39 Attachment body Connection conductor 40 Surface relay conductor 47, 48, 49 Connection conductor 50, 51 Resistor 52 Insulating layer 54, 55 , 56, 57, 58, 59 Solder layer 62 Adhesive TF1, TF2 Thermal fuse R50, R51 Equivalent resistance (value)

Claims (11)

[Claims] An insulating case including an insulating substrate and an insulating cap; a device element housed in the insulating case;
A surface-mounted device having a terminal portion formed on a lower surface of an insulating case, wherein the color of the insulating cap is white. 2. The surface-mounted device according to claim 1, wherein the device element contained in the insulating case contains a fusible alloy that melts at a specific temperature. 3. The device element housed in the insulating case includes a fusible alloy that melts at a specific temperature and a resistor that forcibly blows the fusible alloy by heat generated by energization. Item 2. A surface-mounted device according to item 1. 4. A device element housed in the insulating case includes a fusible alloy that melts at a specific temperature and a plurality of resistors that forcibly melt the fusible alloy by heat generated by energization. The surface mount device according to claim 1. 5. The method according to claim 1, wherein said fusible alloy has a melting point of 250 to 300 ° C.
A surface-mounted device as described. 6. The surface-mounted device according to claim 1, wherein the color of the insulating cap is white, and the color of the insulating substrate is dark. 7. The surface-mounted device according to claim 1, wherein the color of the insulating cap has a lightness of 7 or more and / or a saturation of 0 to 2 in a color stereogram. 8. An insulating case in which the color of the insulating cap is formed in a white system, a device element housed in the insulating case,
A method for mounting a surface-mounted device having a terminal portion formed on a lower surface of an insulating case on a terminal portion of a mounting body, the method comprising: A method for mounting a surface-mounted device, comprising positioning the two terminal portions with solder interposed therebetween and irradiating infrared rays to perform surface mounting. 9. An insulating case in which the color of the insulating cap is formed in a white system, a device element housed in the insulating case,
A method for mounting a surface-mounted device having a terminal portion formed on a lower surface of an insulating case on a terminal portion of a mounting body, wherein the terminal portion on the lower surface and / or the terminal portion of the mounting body in the surface-mounted device are provided. A method for mounting a surface mounting device, comprising forming a solder layer, aligning the two terminal portions, and irradiating infrared rays to perform surface mounting. 10. An insulating case comprising an insulating substrate formed in a dark system color and an insulating cap formed in a white system color, device elements housed in the insulating case, and formed on a lower surface of the insulating case. A method of mounting a surface-mounted device having a terminal portion with a terminal portion of a mounting body, wherein solder is interposed between a terminal portion of a lower surface of the surface-mounting device and a terminal portion of the mounting body. A method for mounting a surface-mounted device, comprising positioning both terminals and surface mounting the same in an infrared reflow furnace. 11. A method for mounting a surface-mounted device according to claim 8, wherein the color of the insulating cap has a lightness of 7 or more and / or a saturation of 0 to 2 in a color solid diagram. .