JPH10261508A - Thermistor element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermistor element capable of ensuring an electric connection of the thermistor base to lead electrodes against a thermal stress if applied. SOLUTION: One force of a thermistor base 1 is tacked to a thermistor base-supporting flat top end face of a lead terminal 2, which is then connected to the base 1 through a wire 3a, an electrode on the other face of the base 1 is electrically connected to an L-shaped lead terminal 4 through a wire 3b, and the wires 3a, 3b connected to the base 1 and the terminal 2, and part of the led terminals 2, 4 are coated with an epoxy resin to form a cover layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor element used for, for example, an electronic component for temperature detection and temperature compensation, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a thermistor element is shown in FIGS.
As shown in FIG. 1, lead terminals 52a and 52b are electrically connected to both surfaces of a plate-like thermistor body 51 by using solder 54, and thereafter, one end of the thermistor body 51 and one of the lead terminals 52a and 52b are formed by resin 53 or the like. Part was coated.

[0003]

In this configuration, when thermal stress is applied to the thermistor element many times, the solder deteriorates,
There has been a problem that the lead terminals 52a and 52b are detached from the thermistor body 51 and electrical connection cannot be established.

Accordingly, an object of the present invention is to provide a thermistor element capable of securing electrical connection between a thermistor element and a lead terminal even when a thermal stress is applied.

[0005]

In order to achieve this object, a thermistor element according to the present invention comprises a first lead terminal having a support, a thermistor element fixed to the support, and a thermistor element. And the second using a wire
And a cover that covers the thermistor body, the wire, and a part of the first and second lead terminals, even if thermal stress is applied to the thermistor element. The above object can be achieved because the wire is buffered.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention uses a first lead terminal having a support, a thermistor element fixed to the support, a thermistor element and a wire. A thermistor element comprising: a second lead terminal connected to the first and second terminals; and a covering body covering the thermistor body, the wire, and a part of the first and second lead terminals. Even if it does, the electrical connection between the thermistor element and the lead terminal can be ensured.

According to a second aspect of the present invention, there is provided a thermistor element according to the first aspect, wherein the support portion has a flat surface, and the thermistor element can be stably fixed.

According to a third aspect of the present invention, there is provided a thermistor element according to the second aspect, wherein the corners of the plane are obtuse or curved, and the lead terminals can be prevented from damaging the thermistor body.

According to a fourth aspect of the present invention, the electrical connection between the first lead terminal and the thermistor body is made by using a wire. It is an element that can secure electrical connection between the thermistor element and the lead terminal even when thermal stress is applied.

According to a fifth aspect of the present invention, there is provided a thermistor element according to any one of the first to fourth aspects, wherein a bent portion is provided at an end of the second lead terminal in the covering. Even if the lead terminal is pulled from the outside of the covering, it is hard to come off.

[0011] The invention according to claim 6 is the first aspect of the present invention, wherein the first
The thermistor element according to any one of claims 1 to 5, wherein a protrusion is provided on at least one of the second lead terminal and the protrusion even if the lead terminal is pulled from outside the cover. Hateful.

According to a seventh aspect of the present invention, the linear expansion coefficient of the covering is equal to or less than the linear expansion coefficient of the wire.
The thermistor element according to claim 7, wherein even if a thermal stress is applied, cracking of the thermistor body, coating, and cutting of the wire due to a difference in linear expansion can be suppressed.

[0013] In the invention according to claim 8, the thermistor body is fixed to the support portion using a conductive adhesive, and the application area of the conductive adhesive is set between the support portion and the thermistor body. The thermistor element according to any one of claims 1 to 7, wherein the conductive adhesive does not adhere to the side surface of the thermistor body, so that a change in the resistance value of the thermistor element is reduced. Can be.

According to a ninth aspect of the present invention, there is provided a thermistor element according to the eighth aspect, wherein the maximum thickness of the conductive adhesive is set to 20 μm or less. It is possible to suppress a change in shape due to the above, and to suppress cracking and peeling of the thermistor body and the conductive adhesive.

According to a tenth aspect of the present invention, the thermistor body is made larger than the supporting portion.
The change in the resistance value of the thermistor element due to the adhesion of the conductive adhesive to the side surface of the thermistor element body can be reduced.

According to an eleventh aspect of the present invention, there is provided a first step of fixing a plate-like thermistor body to a support plane of a first lead terminal having a support plane, and then determining a resistance value of the thermistor body. A second step of measuring, then a third step of trimming the thermistor body to a desired resistance value, and then electrically connecting a second lead terminal and the thermistor body using a wire A fourth step of connecting, and then the thermistor body, the wire and the first and second
And a fifth step of covering a part of the lead terminal with a covering body. A method of manufacturing a thermistor element, wherein the resistance value can be adjusted before completion, so that the yield can be increased.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view of a thermistor element according to the present embodiment, in which lead terminals 2 and 4 are connected to wires 3a and 3b on a square plate-like thermistor element 1 having electrodes on both sides.
To form a coating layer 5.

FIG. 2 is a front and rear view of the thermistor body 1 to which the lead terminals 2 and 4 are connected. First, as shown in FIG. 2B, a thermistor body 1 having electrodes on both sides and having a negative characteristic.
Is temporarily fixed with an adhesive or the like on a lead terminal 2 having a flat surface serving as a support portion of the thermistor body 1 at its tip, and then the electrode of the thermistor body 1 and the lead terminal 2 are connected to a wire 3.
a and electrically connected. By supporting the thermistor body 1 on the plane portion of the lead terminal 2, the lead terminal 2 and the thermistor body 1 can be easily connected by the wire 3a.

Next, as shown in FIG. 2A, the electrode on the surface on the opposite side of the thermistor body 1 and the L-shaped lead terminal 4 were electrically connected by a wire 3b.

Next, the thermistor body 1 and the lead terminals 2
The wires 3a and 3b connecting the wire 4 and a part of the lead terminals 2 and 4 were coated with an epoxy resin to form a coating layer 5, thereby obtaining a thermistor element as shown in FIG.

In the present embodiment, the two lead terminals 2 and 4 are formed on the same plane, but between the lead terminals 2 and 4 so that the wire 3b on the back side does not interfere with the wire bonding. A step may be formed.

(Embodiment 2) FIG. 3 is a rear view of a thermistor body 1 to which lead terminals 6 and 7 according to the present embodiment are connected.

The difference from the first embodiment is that a plurality of wires 3a are used to connect the thermistor body 1 and the lead terminals 6, and the thermistor body 1 and the lead terminals 6
And the electrical connection with it can be made more reliable.

(Embodiment 3) FIG. 4 is a back view of the thermistor body 1 to which the lead terminals 8 and 9 are connected in the present embodiment.

In the first and second embodiments,
A through hole is provided in a plane portion of each of the lead terminals 2 and 6, and a portion exposed from the through hole of the thermistor body 1 and the lead terminals 2 and 6 are connected to each other with the wire 3a. A notch is provided in the flat support portion of the terminal 8 instead of a through-hole, and the thermistor body 1 and the lead terminal 8 are electrically connected using the wire 3a.

(Embodiment 4) FIG. 5 is a sectional view of a thermistor element according to the present embodiment, and FIG.
FIG. 6B is a front view showing a connection form between the lead terminals 12 and 14 and the thermistor body 11, and FIG.

First, as shown in FIG. 6 (a), a conductive adhesive 20 is uniformly applied by screen printing onto a support surface of a lead terminal 12 having a support surface of a thermistor element body 11 at its tip. One electrode surface of the thermistor body 11 having negative characteristics and having electrodes on both surfaces was bonded and electrically connected.

Here, as shown in FIG.
Is smaller than the adhesion area between the support plane and the thermistor element 11, prevents the conductive adhesive 20 from adhering to the side surface of the thermistor element 11, and changes the resistance value of the thermistor element due to the conductive adhesive 20. Was reduced.

As shown in FIG. 6B, by making the area of the support plane of the lead terminal 12 smaller than the area of the bonding surface of the thermistor body 11 to the support plane, the thermistor element of the conductive adhesive 20 is formed. Adhesion to the side surface of the body 11 can be prevented, and a change in resistance value due to the conductive adhesive 20 can be reduced. Further, the method of applying the conductive adhesive 20 can be performed not only by screen printing or a dispenser method but also by a method such as dip, and the workability can be improved.

Further, the thickness of the conductive adhesive 20 applied is made as thin as 20 μm or less, and even if a thermal stress is applied to the thermistor element, a change in shape due to thermal expansion of the conductive adhesive 20 is suppressed. Cracking and peeling of the conductive adhesive 20 were suppressed.

Next, the resistance value of the thermistor body 11 is measured. If the resistance value is not the desired resistance value, the electrodes of the thermistor body 11 are deleted by a laser so that the desired resistance value is obtained. I made it.

Next, the electrode on the other surface of the thermistor body 11 and the L-shaped lead terminal 14 were electrically connected by a wire 13. Thereafter, the periphery of the wire 13 was coated with a silicon-based resin to form a buffer layer 17.

Next, the thermistor body 11 and the lead terminal 1
The wire 13 connected to the wire 2 and a part of the lead terminals 12 and 14 were coated with an epoxy resin to form a coating layer 15 to obtain a thermistor element as shown in FIG.

The key points in the present invention are described below. (1) Lead terminals 2, 4, 6, 7, 8, 9, 12, 14
Is formed of a Fe-based material such as an Fe-Ni alloy or a Cu-based material such as brass, and at least an end portion on a side to be a connection portion with the thermistor bodies 1 and 11 is plated with Ag or Au, whereby gold is formed. The connection with the wires 3a, 3b, 13 was facilitated. Further, the lead terminals 2, 4, 6, 7, 8, 9, 12, 14 are formed by using Fe-based or Cu-based materials.
When connecting to another terminal or the like, welding is facilitated.

(2) The reason why the L-shaped lead terminals 4, 7, 9, 14 are used for connecting to the thermistor element bodies 1, 11 is that the lead terminals 4, 7, 9, 14 are temporarily provided with thermistors. This is because even if a force is applied to pull out the lead terminals 4, 7, 9, 14 from the side opposite to the side connected to the element bodies 1, 11, the lead terminals 4, 7, 9, 14 are hardly removed from the coating layers 5, 15.

For this purpose, even if the shape is not L-shaped, the same effect can be obtained by providing a bent portion at the tip.

Further, as shown in FIGS. 2, 3, 4, and 6, projections 2a and 12a are formed on the portions of the lead terminals 2, 4, 6, 7, 8, 9, 12, and 14 which are covered with the coating layers 5 and 15, respectively. The same effect can be obtained by providing the same.

(3) Lead terminals 2, 4, 6, 7, 8,
The lead terminals 2, 4, 6, 7 are formed by making the corners of the ends connected to the thermistor bodies 1, 11, 12 and 14 obtuse or curved as shown in FIG. ,
8, 9, 12, and 14 can prevent the thermistor bodies 1, 11 from being damaged. As a result, the shapes of the coating layers 5 and 15 can be made almost elliptical, and the lead terminals 2, 4, 6, 7, 8, 9, 12, and 14 cover the coating layers 5, 15.
This makes it difficult to form a thin region, and the strength of the coating layers 5 and 15 can be improved.

(4) The electrodes provided on the surfaces of the thermistor bodies 1, 11 are made of Au, Ag, Ag-Pd, Ag-Pt, Ag-A so as to be easily connected to the gold wires 3a, 3b, 13.
u, Au-Pt and the like.

(5) The coating layers 5 and 15 were formed using a heat-resistant phenol-based or epoxy-based resin or glass. At this time, the coefficient of linear expansion of the coating layers 5, 15 is set to be equal to or less than the coefficient of linear expansion of the wires 3a, 3b, 13, so that even if thermal stress is applied to the thermistor element, the thermistor bodies 1, 11 due to the difference in linear expansion , Coating layer 5, 1
5 and cutting of the wires 3a, 3b, 13 can be suppressed.

(6) As shown in FIG. 5, by providing the buffer layer 17 around the wire 13, the thermal stress applied to the wire 13 can be reduced. As a result, it is possible to widen the selection range of the physical property values of the coating layer 15.
At this time, it is preferable to use a buffer layer 17 having a coefficient of linear expansion smaller than the coefficient of linear expansion of the wire 13. In the embodiment, since a gold wire is used, the buffer layer 17 is formed using an elastic resin of 14 ppm or less. .

It is also effective to provide the buffer layer 17 only around the connection portion where the thermal stress of the wire 13 is concentrated.

(7) As shown in FIG. 7, the thermistor body 1
By providing a plurality of wires 13 for connecting 1 to the L-shaped lead terminal 14, even if the wire 13 is cut, conduction can be obtained. In this case, by making each wire 13 not parallel,
It is possible to secure the strength in various directions of vibration and tensile direction.

(8) As shown in FIG.
The contact area between the thermistor element body 11 and the lead terminal 12 can be reduced by providing the cavity 18 in the support plane of. As a result, the movement of heat from the thermistor body 11 in the direction of the lead terminal 14 can be suppressed.
Responsiveness can be increased.

(9) Moisture resistance, heat resistance, strength and the like can be further improved by forming the coating layers 5 and 15 in a multi-layer structure. At this time, the layer that comes into contact with the wires 3a, 3b, 13 needs to be formed using a material having a linear expansion coefficient equal to or less than the linear expansion coefficient of the wires 3a, 3b, 13.
The upper layer may be formed of a material capable of improving moisture resistance, heat resistance, strength, and the like. In addition, by coating the surfaces of the coating layers 5 and 15 with silicone, wax, or the like, it is possible to suppress infiltration of moisture into the inside and improve moisture resistance.

(10) FIG. 9 shows that the bumps 19 are formed on the second bond portions of the wires 13 so that the peeling and cutting of the wires 13 at the second bond portions can be suppressed.

[0047]

As described above, the thermistor element of the present invention can secure the electrical connection between the thermistor element and the lead terminal due to the buffering effect of the wire even when thermal stress is applied.

In recent years, the use of Sb has been restricted as an environmental problem. Therefore, a demand for a thermistor element that does not require solder containing a large amount of Sb is increasing. On the other hand, the thermistor element of the present invention does not require soldering, and thus is excellent in terms of environmental protection.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a thermistor element according to Embodiment 1 of the present invention.

FIG. 2A is a front view illustrating a connection form between a thermistor element and a lead terminal according to the first embodiment of the present invention;

FIG. 3 is a back view for explaining a connection form between a thermistor element and a lead terminal according to the second embodiment of the present invention;

FIG. 4 is a back view illustrating a connection form between a thermistor element and a lead terminal according to the third embodiment of the present invention;

FIG. 5 is a sectional view of a thermistor element according to a fourth embodiment of the present invention.

FIG. 6 (a) is a front view illustrating a connection form between a thermistor element and a lead terminal according to the fourth embodiment of the present invention.

FIG. 7 is a back view for explaining a connection form between a thermistor element and a lead terminal according to one embodiment of the present invention;

FIG. 8 is a back view illustrating a connection form between a thermistor element and a lead terminal according to one embodiment of the present invention;

FIG. 9 is a side view illustrating a connection form between a thermistor element and a lead terminal according to an embodiment of the present invention.

FIG. 10 is a longitudinal sectional view of a conventional thermistor element.

FIG. 11 is a transverse sectional view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermistor body 2 Lead terminal 2a Projection 3a Wire 3b Wire 4 Lead terminal 5 Coating layer 6 Lead terminal 7 Lead terminal 8 Lead terminal 9 Lead terminal 11 Thermistor body 12 Lead terminal 12a Projection 13 Wire 14 Lead terminal 15 Coating layer 17 Buffer Layer 18 cavity 19 bump 20 conductive adhesive

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kotaro Suzuki 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] A first lead terminal having a support, a thermistor element fixed to the support, a second lead terminal connected to the thermistor element using a wire,
A thermistor element comprising: the thermistor body; the wire; and a coating covering a part of the first and second lead terminals. 2. The thermistor element according to claim 1, wherein the support portion is a flat surface. 3. The thermistor element according to claim 2, wherein the corners of the plane are obtuse or curved. 4. The thermistor element according to claim 1, wherein the electrical connection between the first lead terminal and the thermistor element is made by using a wire. 5. The thermistor element according to claim 1, wherein a bent portion is provided at an end of the coating of the second lead terminal. 6. The thermistor element according to claim 1, wherein a projection is provided on at least one of the first and second lead terminals in the covering. 7. The thermistor element according to claim 1, wherein a linear expansion coefficient of the covering is equal to or less than a linear expansion coefficient of the wire. 8. The thermistor element body is fixed to the support portion using a conductive adhesive, and the application area of the conductive adhesive is smaller than the contact area between the support portion and the thermistor element body. Thermistor element according to any one of claims 1 to 7. 9. The maximum thickness of the conductive adhesive applied is 20 μm.
The thermistor element according to claim 8, wherein: 10. The thermistor element according to claim 8, wherein the thermistor element body is larger than the supporting portion. 11. A first step of fixing a plate-shaped thermistor element to a support plane of a first lead terminal having a support plane, and a second step of measuring a resistance value of the thermistor element. A third step of trimming the thermistor element so as to have a desired resistance value, and a fourth step of electrically connecting a second lead terminal and the thermistor element using a wire. And a fifth step of covering the thermistor body, the wire, and a part of the first and second lead terminals with a covering.