JPH11144913A - Thermistor temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a thermal shock resistance and an environment resistance, by coating a thermistor element and a terminal board with an insulating resin, then covering the surface thereof with a thermal contraction insulator and then covering the insulator with a mold resin. SOLUTION: After iron terminal boards 2a and 2b on which corrosion-proof processing is performed are connected at connections 3a and 3b by soldering to an electrode surface of a thermistor element 1 having an electrode formed on its main plane, an epoxy-based insulating resin 4 is applied to cover the thermistor element 1, the connections 3a and 3b of the terminal boards 2a and 2b and a part of the terminal boards 2a and 2b, and then hardened at a temperature of 120 deg.C, thus carrying out coating. Next, the coating part of the insulating resin 4 is covered with a double-layer thermal contraction insulator 5 having an inner layer made of a polyamide-based insulating adhesive and having an outer layer made of a silicon resin, and contraction and fixation are carried out at 150 deg.C, thus producing a thermistor unit. After that, the entire thermistor unit including a part of the terminal boards 2a and 2b is covered with a PBT- based mold resin 6 by injection molding, thus providing a thermistor sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a temperature sensor utilizing thermistor characteristics, for example, from -40.degree.
The present invention relates to a thermistor temperature sensor that detects a temperature in a severe use environment where a high temperature, humidity, and high vapor pressure are applied, such as between 5 ° C., and performs a temperature alarm or system control.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a conventional thermistor temperature sensor. Terminal plates 2a and 2b having Vickers hardness Hv: 135 to 180 are connected to electrodes of the thermistor element 1 at connection portions 3a and 3b, respectively. The connection portions 3a and 3b to be connected to the thermistor element 1 and the terminal plates 2a and 2b were coated with an epoxy-based insulating resin 4 to a thickness of about 0.2 mm, and injection-molded with a molding resin 5.

[0003]

In the thermistor temperature sensor, the stress caused by the thermal expansion and contraction of the components in a use environment where a severe thermal shock load at a temperature between -40.degree. There is a problem that the connection portions 3a and 3b are broken by concentrating on the connection portions 3a and 3b between the first and the terminal plates 2a and 2b, and the electrical conduction with the thermistor element 1 is impaired.

An object of the present invention is to provide a thermistor temperature sensor having excellent thermal shock resistance and environmental resistance.

[0005]

In order to solve the above-mentioned problems, the present invention provides a method for coating a thermistor element and a terminal plate with an insulating resin, further covering the surfaces with a heat-shrinkable insulator, and then covering with a mold resin. By doing so, the intended purpose is achieved.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention is directed to a thermistor element having a pair of electrodes, a terminal plate connected to each of the electrodes, and an insulating member coated with the thermistor element and the terminal plate. A thermistor temperature sensor comprising a resin, a heat-shrinkable insulator covering a part of the insulating resin and a terminal plate protruding from the insulating resin, and a mold resin covering the heat-shrinkable insulator, By further protecting the surface of the insulating resin with a heat-shrinkable insulating material, the thermal expansion of the components can be improved in the use environment such as oil with severe thermal shock, high temperature, high humidity and severe atmosphere with high vapor pressure. The stress caused by the shrinkage is absorbed to suppress the concentration of stress at the connection between the thermistor element and the terminal plate, thereby ensuring the electrical conduction between the thermistor element and the terminal plate.

According to a second aspect of the present invention, there is provided a thermistor temperature sensor according to the first aspect, wherein the hardness of the terminal plate is adjusted to a Vickers hardness of less than 100. The terminal board absorbs part of the thermal expansion and contraction stress applied to the joint surface between the insulating resin for molding and the terminal board, and the connection between the thermistor element and the terminal board. The concentration of stress on the joint surface and the connection portion is reduced.

According to a third aspect of the present invention, the connecting portion between the thermistor element and the terminal plate is coated with an insulating resin having a thickness of 0.5 mm or more. 2. The thermistor temperature sensor according to 2 above, which firmly protects the thermistor element and the connection between the thermistor element and the terminal board, and partially absorbs the stress applied to the terminal board by severe thermal shock with the insulating resin. This alleviates the concentration of stress at the connection between the thermistor element and the terminal plate.

An embodiment of the present invention will be described below. (Embodiment 1) FIG. 1 shows a thermistor temperature sensor according to an embodiment of the present invention. In FIG. 1, 1 is a thermistor element, 2a and 2b are terminal plates, 3a and 3b are connection parts, 4 is an insulating resin for coating, and 5 is a two-layer type heat-shrinkable insulator whose inner layer is made of an insulating adhesive. , 6 are mold resins.

Next, the manufacturing method will be described. First, a thermistor element 1 having an electrode formed on a main plane is prepared.

Next, terminal plates 2a, 2b made of rust-proof iron (SPCC) are connected to the electrode surfaces of the thermistor element 1 by soldering at connecting portions 3a, 3b, respectively. Connecting portions 3a, 3b of the plates 2a, 2b,
Further, an epoxy-based insulating resin 4 is applied to cover a part of the terminal plates 2a and 2b, and the epoxy resin is cured at a temperature of 120 ° C. to perform coating. The terminal plates 2a and 2b have Hv hardness of 100 and 1 respectively.
The material tempered to 50, and the insulating resin for coating 4 were prepared with a thickness of 0.2 mm and 0.5 mm, respectively.

Next, the coated portion of the insulating resin 4 is covered with a two-layer heat-shrinkable insulator 5 whose inner layer is a polyamide-based insulating adhesive and whose outer layer is a silicone resin, and is shrunk and fixed at a temperature of 150 ° C. to form a thermistor unit. Make it.

Thereafter, as shown in FIG.
The entire thermistor unit including part b was injection-molded with PBT-based mold resin 6 to complete the thermistor sensor.

The obtained thermistor temperature sensor of the present invention and a thermistor temperature sensor manufactured by a conventional method (made with a terminal plate 2a, 2b having an Hv hardness of 150 and a resin coating 4 having a thickness of 0.2 mm) are described. The results of the implemented thermal shock cycle test are shown in Table 1 and the results of the humidity cycle test are shown in FIG.

The thermal shock cycle conditions are as follows: oil in -40 ° C. for 5 minutes → room temperature in air for 10 seconds → oil in 165 ° C. for 5 minutes →
A durability test was performed for 1,000 cycles with one cycle of 10 seconds at room temperature in the atmosphere, and a 2,000 cycle durability test with holding at -20 ° C and 85Rh% for 1 minute and holding at + 80 ° C and 85Rh% for 1 minute under moisture-resistant cycle conditions.

[0016]

[Table 1]

As shown in (Table 1), the conventional product is 500
Thermistor element 1 and terminal plate 2
The connection portions 3a and 3b with the a and 2b are broken, and 100
At 0 cycles, all samples break. On the other hand, when the terminal boards 2a and 2b of the present invention were tempered to have a hardness of 100 and the insulating resin 4 was applied to a thickness of 0.5 mm, no breakage was observed even after 1000 cycles. On the other hand, when the hardness of the terminals 2a and 2b was adjusted to 100 and the insulating resin 4 was applied to a thickness of 0.2 mm, two breaks were observed after 1000 cycles. On the other hand, when the terminal plates 2a, 2b have been hardened to a hardness of 150, no abnormality is found in the connection portions 3a, 3b up to 500 cycles regardless of the thickness of the resin coating 4.
Breakage has occurred at 1000 cycles. This is because, at the time of injection molding of the molding resin 6, the insulating adhesive of the two-layer heat-shrinkable insulator 5 absorbs the injection pressure at the time of molding the molding resin 6, and stresses the thermistor element 1 and the connecting portions 3a and 3b. -40 ° C to 165 ° C
The thermal expansion and contraction stresses of the molded resin 6 at the temperature between them are absorbed, and the thermistor element 1 and the connecting portions 3a and 3b are absorbed.
This indicates that there is an effect of alleviating concentration of stress.

As shown in FIG. 2, the thermistor temperature sensor of the present invention has almost no change in the resistance value of the thermistor element 1 even after a lapse of 2000 cycles of the moisture resistance test, whereas the conventional thermistor element 1 has a larger number of thermistors as the cycle number increases. It can be seen that the resistance value of the element 1 gradually increases. This is because the insulating adhesive of the heat-shrinkable insulator 5 firmly wraps and protects the joint between the insulating resin 4 and the terminal plates 2a and 2b, and the difference in thermal expansion between the terminal plates 2a and 2b and the insulating resin 4. This indicates that moisture and foreign substances that degrade the characteristics of the thermistor element 1 are prevented from entering from the interface gap generated by this, and that there is an effect of stabilizing the durability performance as a thermistor temperature sensor.

From the above results, in order to clear a severe thermal shock of -40.degree. C. to 165.degree. C., a terminal plate 2a, 2b having a hardness of less than 100 is used. In order to cover the connection portions 3a and 3b with the insulating resin 4 having a thickness of at least 0.5 mm or more and improve the moisture resistance, the insulating resin 4 and the terminal plates 2a and 2b are required.
It can be seen that it is necessary to further cover the joint b with the heat-shrinkable insulator 5. Thereby, a thermistor temperature sensor having excellent durability performance can be provided.

[0020]

According to the present invention, the thermistor element and the thermistor element and the terminal plate are covered with an insulating resin.
By further covering the surface and part of the terminal board with a heat shrink insulator, and further covering the outside with a mold resin,
A highly reliable thermistor temperature sensor having excellent thermal shock resistance and moisture resistance can be provided.

[Brief description of the drawings]

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

FIGS. 2 (a) and (b) are graphs of a moisture resistance cycle test of a product of the present invention and a conventional product.

FIG. 3 is a cross-sectional view of a conventional thermistor temperature sensor.

[Explanation of Signs] 1 Thermistor element 2a, 2b Terminal plate 4 Insulating resin 5 Heat-shrink insulator 6 Mold resin

Continued on the front page (72) Inventor Tsunemasa Hashimoto 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] A thermistor element having a pair of electrodes;
A terminal plate connected to each of the electrodes, an insulating resin coating the thermistor element and the terminal plate, and a heat-shrinkable insulator covering a part of the insulating resin and the terminal plate protruding from the insulating resin. And a mold resin covering the heat-shrinkable insulator. 2. The hardness of the terminal plate is Vickers hardness Hv: 1.
2. The thermistor temperature sensor according to claim 1, wherein the temperature of the thermistor is less than 00. 3. The thermistor temperature sensor according to claim 1, wherein a connection portion between the thermistor element and the terminal plate is coated with an insulating resin having a thickness of 0.5 mm or more.