JPH0831605A - Surface-mount thermistor - Google Patents

Abstract

PURPOSE:To provide a surface-mount thermistor suitable for surface mounting of a thermistor element which is housed in a case. CONSTITUTION:The title surface-mount thermistor is composed of a case 12, having an aperture 12a on the upper part, a tabular thermistor element 1 on which electrodes 1a and 1b are formed on both opposing main surfaces, and a terminal 14 having a tabular cover 14, to be fixed to the aperture part 12a of the case, on one end, and each end of the terminals 11 and 14 are provided outside the lower surface of the case 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor element, and more particularly to a surface mount type thermistor in which a current controlling thermistor element that generates heat is suitable for surface mounting.

[0002]

2. Description of the Related Art A conventional surface mount type thermistor will be described with reference to FIG. There is a disk-shaped thermistor element 1 having electrodes 1a and 1b formed on both main surfaces. The thermistor element 1 is placed at a predetermined position on the circuit board 4 on which the cream solder 3 is printed and reflow-soldered so that the electrode 1a is electrically connected to one electrode 4a of the circuit board 4. Next, one end of the lead terminal 5 made of a conductor is attached to the electrode 1
Then, the other end of the lead terminal 5 is soldered to the other electrode 4b of the circuit board 4.

As described above, in the conventional surface mount type thermistor, the thermistor element 1 is directly connected to the circuit board 4 via the solder H.

[0004]

However, the surface mount type thermistor having such a structure has the following problems.

1. In order to mount the thermistor element 1 on the circuit board 4, the step of reflow-soldering the thermistor element 1 on the circuit board 4 and the lead terminals 5 on the circuit board 4 are performed.
And a step of soldering to the thermistor element 1 is required.

2. Electrodes 1 on both main surfaces of the thermistor element 1
Since a and 1b cannot be soldered at the same time, the heat generated when reflow soldering the electrode 1a first causes the electrode 1b to
The solderability of is deteriorated. Similarly, if the order of soldering is reversed, the solderability of the electrode 1a to be soldered later deteriorates.

3. The thermistor element 1, which is weak against heat stress, is subjected to heat stress twice by soldering, and cracks are likely to occur in the thermistor element 1.

4. Since the heat generated by the thermistor element 1 is directly transferred to the circuit board 4, the circuit board 4 and the circuit board 4
It may adversely affect the above electronic components.

An object of the present invention is to solve the above-mentioned problems, and to provide a surface mount type thermistor suitable for surface mounting by housing a thermistor element which generates heat in a case. .

[0010]

In order to achieve the above object, in the surface mount type thermistor of the present invention, a surface mounting type thermistor is opposed to a case having an opening at an upper portion and one end of one terminal is disposed inside a lower surface. A plate-like thermistor element having electrodes formed on both main surfaces thereof, and another terminal having a plate-like lid portion fixed to the opening at one end, the one terminal and the other terminal Each of the other ends is provided outside the lower surface of the case.

Further, a case having an opening in the upper portion, a contact portion higher than the lower surface on the inner side of the lower surface, and one terminal led out from the contact portion to the outer surface of the lower surface, and electrodes facing both main surfaces are provided. A plate-shaped thermistor element in which is formed,
The other terminal having a plate-shaped lid portion fixed to the opening at one end, and the thermistor element is loaded higher than the lower surface inside the case, and the lid of the other terminal is placed in the opening. Are fixed, and the other ends of the one terminal and the other terminal are bent and formed outside the lower surface of the case.

Further, in the method of locking the case and the lid, the end of the case opening has an end face on the inner side and a raised end face on the outer side, and the end of the other terminal is covered. It is characterized in that it is brought into contact with an inner end surface portion of the opening portion, the outer higher end surface portion is deformed, and the lid portion of the other terminal is integrally locked to the case.

Further, a protrusion is provided on the end surface near the opening of the case, a through hole is provided in the lid portion of the other terminal corresponding to the protrusion, and the protrusion is locked in the through hole. Is characterized by.

The one terminal is made of an elastic material folded back by 180 degrees and has a contact portion at one end.
The other end is provided outside the lower surface of the case.

The thermistor element is a semiconductor element for current control, which is any one of a positive characteristic thermistor element, a negative characteristic thermistor element and a sudden resistance change thermistor element.

[0016]

In the present invention, since the thermistor element is sandwiched between the terminals in the case as described above, it is not directly soldered to the electrode of the thermistor element. Also,
In order to solder the surface mount type thermistor to the circuit board, one reflow soldering is sufficient. Further, since the thermistor element has a space between the thermistor element and the circuit board, the heat generated by the thermistor element can be prevented from being directly transmitted to the circuit board.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, a surface mount type thermistor 10 is provided.
Is composed of a case 12 having one terminal 11, a thermistor element 1, and the other terminal 14.

The case 12 has a housing 15 made of an insulating material having an opening 12a at the top, and one terminal 11 led out from the inside of the lower surface of the housing 15 to the outside of the lower surface. One of the terminals 11 preferably has a contact portion 11a having a spring property at a position slightly higher than the lower surface of the case 12, and is folded 180 degrees from this contact portion 11a and then led out to the outside of the lower surface via the side surface of the housing 15. Has been done.
Further, the opening end of the case 12 has an inner opening end 1 inside thereof.
5a, an outer open end 15 which is a higher end face portion on the outside thereof
b is formed.

The plate-like thermistor element 1 has electrodes 1a and 1b formed on opposite main surfaces thereof, and is a thermistor element for current control, that is, a positive characteristic thermistor element, a negative characteristic thermistor element, or a resistance sudden change thermistor element. Is one of.

The other terminal 14 is formed with a lid portion 14a, one of which comes into contact with the inner opening end 15a of the case 12, and the other of which has a flat lead portion 14b.

In the surface mount type thermistor 10, the thermistor element 1 is loaded in the case 12, the lid portion 14a is brought into contact with the inner opening end 15a from above the case 12, and the outer opening end 15b is deformed inward. The lid 1
4a is fixed to the opening 12a of the case 12. The lead portion 14b of the other terminal 14 is led out to the bottom surface through the outside of the side surface of the case 12 so as to face the one terminal 11.

The surface mount type thermistor 10 having such a structure.
The thermistor element 1 is loaded in the case 12, the lower electrode 1a is the contact portion 11a, and the upper electrode 1b is the lid portion 1.
By making elastic contact with each of the terminals 4a, the terminals 11 and 14 are electrically connected without being soldered. The external connection terminal portions of both terminals 11 and 14 are arranged on the lower surface of case 12 so as to face each other. Therefore, for example, by mounting the surface mount type thermistor 10 on a circuit board coated with cream solder and performing reflow soldering, the external connection terminal portion arranged on the lower surface of the case 12 is soldered by heating once. Can be attached. Further, in the surface mount type thermistor 10, since the contact portion 11 a is located slightly higher than the lower surface of the case 12, a space S is formed between the lower surface of the case 12 and the thermistor element 1.

Another embodiment according to the present invention will be described with reference to FIGS.

Referring to FIG. 3, the surface mount type thermistor 20.
Is composed of one terminal 21, a case 22, a thermistor element 1, and the other terminal 24.

One of the terminals 21 is made of a spring material and has an arc-shaped contact portion 21a at one end, and the other end having a substantially U-shaped cross section from the contact portion 21a.

The case 22 is made of an insulating material having an opening 22a in its upper portion, has a space in which the thermistor element 1 can be loaded, and has a side surface on which one terminal 21 can be inserted. The notch K is formed to the bottom. The opening end of the case 22 has an inner opening end 22 inside thereof.
b, the outer open end 22c, which is a higher end face portion on the outside thereof
Are formed, and there are a plurality (4 in the figure) at the inner open end 22b.
22d is formed.

The other terminal 24 is composed of a lid portion 24a, one of which comes into contact with the inner opening end 22b of the case 22, and the other of which is a flat lead portion 24b.
Corresponding to the second projection 22d, a through hole 24c into which the projection 22d can be inserted is provided.

In the surface mount type thermistor 20, one terminal 21 is mounted so that its contact portion 21a is inside the lower surface of the case 22 and the substantially U-shaped section is sandwiched between the lower surfaces, and then the thermistor element 1 is mounted on the case 22. Insert inside and cover 2
4a is brought into contact with the inner opening end 22b from above the case 22 and the outer opening end 22c is deformed inward, whereby the lid portion 24a is fixed to the opening portion 22a of the case 22. Then, the lead portion 24 of the other terminal 24
b is drawn to the bottom through the outside of the side surface of the case 22 so as to face the one terminal 21.

The surface mount type thermistor 20 having the above structure.
The thermistor element 1 is loaded in the case 22, the lower electrode 1a is the contact portion 21a, and the upper electrode 1b is the lid portion 2.
By elastically contacting each of the terminals 4a, they are electrically connected to both terminals 21 and 24 without being soldered. The external connection terminal portions of both terminals 21 and 24 are arranged on the lower surface of the case 22 so as to face each other. Therefore, for example, by mounting the surface mount type thermistor 20 on a circuit board coated with cream solder and performing reflow soldering, the external connection terminal portion arranged on the lower surface of the case 22 is soldered by heating once. Can be attached. Further, in the surface mount type thermistor 20, since the contact portion 21 a is located slightly higher than the lower surface of the case 22, a space S is formed between the lower surface of the case 22 and the thermistor element 1.

The protrusion 22d of the case 22 is inserted into the through hole 24c of the lid 24, and the protrusion 22d is deformed to cover the lid 2
It is also possible to fix 4 to the case 22, and in this case, the outer open end 22c of the case 22 may be omitted.

[0032]

As described above, in the surface mount type thermistor according to the present invention, since the external connection terminal portion is arranged on the lower surface of the case, it can be soldered to the circuit board by one reflow soldering. it can. Further, since the thermistor element is not directly soldered, the electrode of the thermistor element is not heated and the solderability is not deteriorated. When soldering to the circuit board, the thermistor element is only subjected to thermal stress once, and since the heat of soldering is transferred to the thermistor element through the case and the space, the temperature is higher than that of direct soldering. Is low and cracks do not occur in the thermistor element.
Furthermore, the heat generated by the thermistor element during use is transmitted to the circuit board through the space inside the case bottom surface and the case, resulting in a low temperature and affecting the circuit board and other electronic components near the surface mount type thermistor. Can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a surface mount type thermistor according to the present invention.

2 is a top view of the surface mount type thermistor of FIG. 1. FIG.

FIG. 3 is a sectional view of another embodiment of the surface mount type thermistor according to the present invention.

FIG. 4 is a perspective view of a case in FIG.

FIG. 5 is a perspective view of the other terminal in FIG.

FIG. 6 is a partial side sectional view of a conventional surface-mounted thermistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermistor element 1a, 1b Electrode 10 Surface mount type thermistor 11 One terminal 11a Contact part 12 Case 12a Opening 14 Other terminal 14a Lid 15b One step higher end face (outer open end) 22d Protrusion 24c Through hole

Claims (6)

[Claims] 1. A case having an opening at an upper portion thereof, wherein one end of one terminal is arranged inside a lower surface, a plate-like thermistor element having electrodes formed on opposite main surfaces thereof, and fixed to the opening. The other terminal having a plate-shaped lid portion at one end, and the other ends of the one terminal and the other terminal are provided outside the lower surface of the case. Thermistor. 2. A case having an opening at the top, a contact portion higher than the lower surface inside the lower surface, and a terminal having one terminal led out from the contact portion to the outside of the lower surface, and electrodes on both main surfaces facing each other. A plate-shaped thermistor element formed, and the other terminal having a plate-shaped lid portion fixed to the opening at one end, the thermistor element is loaded inside the case higher than the lower surface, A surface mount type thermistor characterized in that a lid of the other terminal is fixed to the opening, and the other ends of the one terminal and the other terminal are bent and formed outside the lower surface of the case. 3. An end portion of the case opening portion has an end face portion inside thereof and a higher end face portion outside thereof, and a lid portion of the other terminal is in contact with an end face portion inside the opening portion. The surface mount type thermistor according to claim 1 or 2, wherein the outer end of the raised end face is deformed to integrally lock the cover of the other terminal to the case. 4. A protrusion is provided on an end surface near the opening of the case, a through hole is provided in a lid portion of the other terminal corresponding to the protrusion, and the protrusion is locked in the through hole. The surface mount type thermistor according to claim 1 or 2. 5. The elastic material is used for the one terminal.
The surface mount type thermistor according to any one of claims 1 to 4, wherein the surface mount type thermistor is formed by folding back, has a contact portion at one end, and has the other end provided on the outside of the lower surface of the case. 6. The thermistor element is a current control thermistor element, which is any one of a positive characteristic thermistor element, a negative characteristic thermistor element, and a rapid resistance change thermistor element. Surface mount type thermistor.