JPS63172402A - Manufacture of organic positive characteristic thermistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing an organic positive temperature coefficient thermistor that utilizes the positive resistance/temperature characteristics exhibited by an organic polymer material mixed and dispersed with conductive particles. In particular, the present invention relates to a method of soldering electrodes and leads in the organic positive temperature coefficient thermistor.

<Prior Art> Conventionally, an organic positive temperature coefficient thermistor having a structure as shown in FIG. 1 has been known. This organic positive temperature coefficient thermistor 10 includes an element body 11 made of an organic polymer material such as polyethylene mixed and dispersed with conductive particles such as carbon black. And this element 1
1 are provided with electrodes 12.1 made of nickel or the like on both main surfaces.
2 is formed by means such as thermocompression bonding or plating of metal foil.

Moreover, each inner end of a lead M13.13 is connected to the outer surface of each of these electrodes 12.12 by soldering.

Conventionally, in manufacturing such an organic positive temperature coefficient thermistor lO, the electrode 12.12 and the lead wire 13 are generally connected.
．． Soldering with 13 is performed under the following conditions. That is, while 4/6 eutectic solder having a melting point of 183°C is used as the soldering material, the working temperature of this soldering, that is, the soldering temperature is about 210 to 230°C.

<Problems to be Solved by the Invention> By the way, the following problems occurred in the soldering of the electrodes 12.12 and the leads wA13.13. In other words, since the melting point of the element material made of organic polymer material mixed and dispersed with conductive particles is generally used at 100 to 125°C, the melting point of this element material is sometimes 210 to 230°C when soldering. However, if the electrodes 12 and 12 formed on both main surfaces of the element body 11 are exposed to high temperature conditions, they will undergo rapid thermal expansion.
Since the thermal expansion coefficient of the metal material is much smaller than that of the element material, the expansion of these electrodes 12 and 12 cannot follow the rapid expansion of the element body 11. Electrode 12.12 from the main surface of element body 11
peeling is likely to occur, increasing its resistance value.

Moreover, the high temperatures encountered during such soldering alter and deteriorate the properties of the element material itself, causing a change in its resistance value. Therefore, in the conventional organic positive temperature coefficient thermistor 10, the resistance value changes due to soldering, and the resistance value varies widely from product to product, causing problems in its reliability.

In view of these conventional problems, the present invention provides a method for manufacturing a resistor with a long-lasting characteristic that can prevent changes and variations in resistance value due to soldering and improve reliability. With the goal.

Means for Solving the Problems> In order to achieve the above object, the present invention provides a conductive material formed on both main surfaces of an element body made of an organic polymer material in which conductive particles are mixed and dispersed. In a method for manufacturing an organic positive temperature coefficient thermistor in which lead wires are connected to electrodes by soldering,
The melting point of the solder material used for the soldering is set at a temperature range of 5°C to 45°C higher than the melting point of the element material, and the temperature for soldering is set at a temperature range of 30°C to 70°C higher than the melting point of the element material.
This method is characterized in that soldering is performed at a temperature range that is higher than 10°C.

<Example> Hereinafter, the present invention will be explained in detail based on examples.

Since the organic positive temperature coefficient thermistor used to carry out the method of the present invention has the same structure as the conventional example, its structure will be explained based on FIG. That is, the organic positive temperature coefficient thermistor 10 of the present invention includes the element body 11, the electrodes 12.12, and the lead wires 13.1.
It is composed of 3.

The element body 11 is formed of an element material made of an organic polymer material in which conductive particles are mixed and dispersed.

Carbon black, graphite, metal powder, etc. are used as such conductive particles, and polyethylene, polypropylene, or polybutadiene resin materials are used as the organic polymer material.

Electrodes 12 and 12 are formed on both main surfaces of this element body 11 by thermocompression bonding or plating of metal foil made of nickel, for example.
2. Each outer surface of 12 has a lead &I13. ．． The inner ends of 13 are connected to each other by soldering. Note that the reference numeral 14 in the figure indicates the element body 11 and the lead wires 13 and 13.
This is an insulating resin for sealing the inner end of the

Next, a method of soldering the electrode 12.12 and the lead wire 13.13 according to the present invention will be described.

(Condition I) The solder materials used for soldering are ■tin (Sn) and lead (
(1) A material whose main component is tin and lead with a predetermined amount of bismuth (B) added to it and a predetermined amount of cadmium (Cd);
i) A material whose main components are tin and lead, and a predetermined amount of both cadmium and bismuth added thereto, the melting point of which is the same as that of the element material. The temperature range is set to be 5°C to 45°C higher than the melting point of 100°C to 125°C. The lowest temperature of the melting point of this solder material is set to be 5°C higher than the melting point of the element material because when the organic positive temperature coefficient thermistor 10 is used and the element 11 is energized to generate self-heating, the solder material In order to prevent the inconvenience of melting,
It has been confirmed through experiments that no problem occurs if the melting point of the solder material is 5° C. higher than the melting point of the element material. Regarding the maximum temperature, it has been experimentally confirmed that the temperature of soldering, which will be described later, is the upper limit temperature at which the soldering temperature can be avoided from becoming too high.

(Condition ①) Then, using such solder material, the electrode 12°12
Solder the inner end of lead wire 13.13.
At this time, the soldering temperature is 30°C higher than the melting point of the base material.
The temperature range is 70 degrees Celsius higher than the average temperature. The reason for this soldering is that the lowest temperature is 30°C higher than the melting point of the base material, or 25°C higher than the melting point of the solder material, because the temperature of the workpiece is low. This is to prevent the material from coagulating during work and impairing workability, and the temperature of 25°C was determined through experiments. In addition, the reason why the maximum temperature for soldering was set to 70°C higher than the melting point of the base material was because
If soldering is performed at a temperature that is 70°C or more higher than the melting point of the element material, it may cause deterioration of the element material or electrode 1.
This is because separation from the element body 11 of 2.12 is likely to occur, and this is also based on experimental results.

By the way, in order to compare the organic positive temperature coefficient thermistor manufactured by the present invention with conventional products, the inventors of the present invention conducted tests on the variation range of resistance value and the rate of change in resistance on a large number of samples. The test results shown in the table were obtained. In addition, in this table, the code X is the average value of the resistance value of the previous sample for soldering, the code y is the average value of the resistance value of the sample after soldering, and the code σ is the resistance value of the sample after soldering. It shows the range of variation.

The following samples are used in this test. First, in Example 1, the melting point is 125°C.
Electrodes 12 and 12 made of nickel were formed on both main surfaces of the element body 11 made of the element material of , to form a sheet with a thickness of 0.4 fi, and this was cut into a size of 10 Tsuru angle. , the inner ends of lead wires 13.13 are soldered to the outer surfaces of the electrodes 12.12, respectively. In this soldering, it is made of 5n-Pb-Cd and has a melting point of 145°C.
Use a soldering material that is
℃.

The second embodiment has the same configuration as the first embodiment, with the only difference being the soldering. That is, in this soldering, it is made of 5n-Pb-Bi and has a melting point of
A soldering material heated to 130°C is used, and the soldering temperature is 160°C.

Next, Comparative Example 1 has the same structure as Example 1, and the solder material used therein is 5n-Pb-Cd having a melting point of 145 DEG C., as in Example 1.

However, in Comparative Example 1, the soldering temperature is 200° C., which is 75° C. higher than the melting point of the base material, 125° C.

Comparative Example 2 also has the same configuration as Example 1, and differs only in soldering.

That is, in this soldering, 476 eutectic solder with a melting point of 183°C is used, and the soldering temperature is 220°C.
It is said that Therefore, this comparative example 2 is a conventional product.

(Hereinafter, blank space) Table 1 The experimental results shown in Table 1 reveal the following. That is, when Example 1 and Example 2 are compared with Comparative Example 2, which is a conventional product, the variation range (σ) of the resistance value is from 25.0-Ω to 3.0 mΩ or less, and the resistance change rate is has also significantly decreased from 60.6% to less than 10%. In Comparative Example 2, some of the electrodes sometimes peeled off from the element body during soldering.

Comparative Example 1 and Example 1 differ only in soldering temperature from Example 1. When comparing Example 1.2, the resistance value variation range (σ) of Example 1.2 is from 6.38 mΩ to 3.38 mΩ. O
The resistance change rate is approximately 1/2 of mΩ or less, and the resistance change rate is 26.4.
% to less than 10%. From this, it can be seen that even if the solder material is the same, if the soldering temperature is too high, the range of variation in resistance value and the rate of change in resistance will increase.

Next, a 0N-OFF cycle (lifetime) test was conducted on each of the samples described above, and the following results were obtained. That is, in Example 1 and Example 2, the resistance value change in 500 cycles was 20% or less, whereas
In Comparative Example 1, the resistance value change exceeds 50%, and in Comparative Example 2, which is a conventional example, it exceeds 150%.

From the results of the various tests explained above, it can be confirmed that the resistance value of an organic positive temperature coefficient thermistor is greatly affected by the melting point of the solder material and its soldering temperature. It was confirmed that there is less variation and change in resistance value than with conventional products, and that the lifespan is longer.

<Effects of the Invention> As described above, according to the manufacturing method of the present invention, the melting point of the solder material and its soldering temperature are set lower than conventional ones, based on the melting point of the element material, so that organic positive properties are achieved. Changes in the resistance value of the thermistor and variations in resistance value between products can be reduced, and its lifespan can be extended, and its soldering does not cause any trouble to the work. The reliability of such an organic positive temperature coefficient thermistor can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an organic positive temperature coefficient thermistor. 10...Organic positive temperature coefficient thermistor, 11... elemental body, 12... Electrode, 13... Lead wire.

Claims (1)

[Claims] (1) A method for manufacturing an organic positive temperature coefficient thermistor in which lead wires are connected by soldering to electrodes formed on both main surfaces of an element body made of an organic polymer material in which conductive particles are mixed and dispersed, The melting point of the solder material used for soldering is set to a temperature range of 5 to 45 degrees Celsius higher than the melting point of the element material, and the soldering temperature is set to a temperature range of 30 to 70 degrees Celsius higher than the melting point of the element material.
A method for manufacturing an organic positive temperature coefficient thermistor, characterized in that soldering is performed at a temperature range higher than 0.degree.