JP2001015303A - Thermistor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermistor element having superior durability by reducing thermal stresses, when an electrode is electrically connected with a lead terminal for preventing solder leach of the electrode. SOLUTION: This thermistor element is provided with a thermistor element assembly 1, two electrodes 2a, 2b formed on both surfaces of the thermistor element assembly 1, two lead terminals 3a and 3b which are electrically connected with the electrodes 2a and 2b, respectively, and conductive adhesive agents 4a, 4b which electrically connect the electrodes 2a, 2b with the lead terminals 3a, 3b. The conductive adhesive agents 4a, 4b are composed of a resin and conductive material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to, for example, temperature detection,
The present invention relates to a thermistor element used for an electronic component for temperature compensation.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a lead terminal 3a, 3b is electrically connected to electrodes 2a, 2b of a plate-like thermistor element 1 by solder dips or the like, as shown in FIG. Was taken.

[0003]

In this configuration, since the solder is used for the electrical connection between the thermistor body 1 and the lead terminals 3a, 3b, the solder heated above the melting point when performing the solder dip is used. Since the thermistor body 1 is immersed in the thermistor element, there is a problem that a large thermal stress is applied to the thermistor body 1 or that the electrodes 2a and 2b are soldered after soldering, thereby deteriorating the durability performance of the thermistor element. Was.

Accordingly, an object of the present invention is to provide a thermistor element having excellent durability.

[0005]

In order to achieve this object, a thermistor element according to the present invention comprises a thermistor element, at least two electrodes formed on the thermistor element, and an electrically connected electrode. A thermistor element comprising at least two lead terminals to be connected, and a conductive adhesive for electrically connecting the electrodes and the lead terminals, wherein the conductive adhesive is formed of a resin and a conductive substance; Not to prevent solder cracking of the electrode, and to reduce the heat stress by electrically connecting the electrode and the lead terminal at a lower heating temperature than the solder, and to have excellent durability. Can be.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a thermistor element, at least two electrodes formed on the thermistor element, and at least two electrodes electrically connected to the electrodes. A thermistor element comprising two lead terminals and a conductive adhesive for electrically connecting the electrodes and the lead terminals, and the conductive adhesive is formed of a resin and a conductive substance. Can be reduced when electrically connected.

According to a second aspect of the invention, there is provided a thermistor element according to the first aspect, wherein the conductive substance is a metal powder.
Good electrical bonding properties can be obtained.

According to a third aspect of the present invention, the metal powder is A
The thermistor element according to claim 2, wherein the thermistor element is at least one of g, Au, Pt, Pd, Ni, Cu, and Zn.

The invention according to claim 4 is the thermistor element according to any one of claims 1 to 3, wherein the conductive adhesive is applied so as to cover only a part of the electrode surface. After the electrodes and the lead terminals are electrically connected, the thermal stress at the joint due to thermal shock or the like can be reduced.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view of a thermistor element according to the present embodiment.
2a and 2b of the plate-like thermistor body 1 on which
The lead terminals 3a, 3b are brought into contact with each other, conductive adhesives 4a, 4b using an epoxy resin are applied to the contact portions with a dispenser, and pre-dried at 80 ° C. with a drier, then at 150 ° C. It is solidified.

The important points about the thermistor element of the present invention are described below.

(1) When the conductive adhesives 4a and 4b are used, a treatment such as heating is performed in order to cure the resin constituting the conductive adhesive. In comparison, the thermal stress applied to the thermistor body 1 is small, and a change in the thermistor characteristics (resistance value, B constant) can be suppressed.

(2) The conductive adhesives 4a and 4b are
It is desirable to cover only a part of the surfaces of a and 2b. That is, the amount of the conductive adhesives 4a and 4b to be applied is minimized and the generation of stress due to the difference in thermal expansion of the components of the thermistor element is reduced. Because, when materials with different thermal expansions are bonded, the bonding distance (contact distance)
This is because the smaller the value is, the smaller the amount of expansion displacement when heat is applied, and as a result, the stress between the substances becomes smaller.
Accordingly, by minimizing the amount of the conductive adhesives 4a and 4b used, the bonding distance is reduced, which is advantageous for thermal stress.

(3) The lead terminals 3a and 3b are made of a material having good wettability with the conductive adhesives 4a and 4b, or the lead terminals 3a and 3b are coated with a material having good wettability. Is desirable.

(4) In the above embodiment, epoxy resin is used as the main resin component of the conductive adhesives 4a and 4b at a curing temperature of 150 ° C. This is because the use of the conventionally used eutectic point solder required heating to around 230 ° C., thereby reducing the thermal stress applied to the thermistor body 1. The epoxy resin is a thermosetting resin having a softening point equal to or higher than the operating temperature and in which the adhesive strength is hard to change even when heat is applied.
Instead of the epoxy resin, a thermosetting resin such as a silicone resin or a thermoplastic resin such as a polyurethane resin may be used. However, it is desirable to use a resin that cures at a low temperature in order to minimize thermal stress as much as possible. However, since the operating temperature of the thermistor element is around room temperature to 150 ° C., if the softening point is below the maximum operating temperature, the bonding strength is weakened. Therefore, it is desirable to select a resin having a softening point higher than the maximum operating temperature.

Further, flake silver powder was used as a metal component. This is because when the conductive adhesives 4a and 4b are cured to generate conductivity, conductivity is more easily exerted than spherical metal powder. In other words, before the curing, the silver powder is dispersed in the epoxy resin, and the silver powder does not contact each other, and the conductive adhesives 4a and 4b themselves do not have conductivity. This is because they have electrical conductivity. At this time, the resin is present in the gap between the metal components and generates a bonding force.

In the above embodiment, silver is used.
At least one metal component among Ag, Au, Pt, Pd, Ni, Cu, and Zn may be used.

(5) In the above embodiment, the electrode 2
Silver was used as the metal component in the conductive adhesives a and 2b and the conductive adhesives 4a and 4b, because the same kind of metal is more advantageous in electrical coupling. When the metal components of the electrodes 2a and 2b and the conductive adhesives 4a and 4b are a mixture of two or more components, the same effect can be expected by making the respective main components the same.

(6) In the above embodiment, rod-shaped lead terminals 3a and 3b are used. However, in order to increase bonding strength, plate-like lead terminals 3a and 3b are used.
Is more desirable.

(7) The surfaces of the electrodes 2a and 2b are preferably rougher than smoother because the bonding strength with the conductive adhesives 4a and 4b is higher. For example, the surface becomes rougher when formed by screen printing or metallikon than when the electrodes 2a and 2b are formed by vapor deposition or sputtering. Therefore, there is no need to provide a step of roughening the surface.

[0022]

As described above, the present invention can provide a thermistor element having excellent durability.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a thermistor element according to an embodiment of the present invention.

FIG. 2 is a front sectional view of a conventional thermistor element;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermistor body 2a Electrode 2b Electrode 3a Lead terminal 3b Lead terminal 4a Conductive adhesive 4b Conductive adhesive

Claims (4)

[Claims] 1. A thermistor body, at least two electrodes formed on the thermistor body, at least two lead terminals electrically connected to the electrodes, and an electrical connection between the electrodes and the lead terminals. A thermistor element comprising: a conductive adhesive connected to the conductive adhesive; and the conductive adhesive formed of a resin and a conductive substance. 2. The thermistor element according to claim 1, wherein the conductive substance is a metal powder. 3. The metal powder is Ag, Au, Pt, Pd, N
3. At least one of i, Cu, and Zn.
5. The thermistor element according to 1. 4. The thermistor element according to claim 1, wherein the conductive adhesive covers only a part of the electrode surface.