JPH02184001A - Manufacture of positive property thermistor - Google Patents

Abstract

PURPOSE:To simplify a manufacturing process by injecting crystalline resin material including conductive powder in a mold after placing a lead wire in this mold beforehand so as to unite both in a body. CONSTITUTION:Crystalline resin material including generally-used conductive powder is prepared. A mold 7 for forming which is equipped with an injection port 5 is prepared, and a pair of lead wires 8 and 9 are so arranged beforehand as to oppose at a desired space L in this mold 7. Curved parts 8a and 9a for falling prevention are made in advance near the tips of the lead wires 8 and 9. Crystalline resin material 11 is injected as shown by an arrow from an injection port 6 into the mold 7 with a guide jig 10. Hereby, a pair of lead wires 8 and 9, which are arranged in advance, are covered with crystalline resin material 11. By removing the mold 7 next, a unit element, where a pair of lead wires 8 and 9 and crystalline resin material 11 are united, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a positive temperature coefficient thermistor.

(Prior art) A positive temperature coefficient thermistor has a positive temperature coefficient in the region 1 or W2 above the Curie temperature TC in the resistance-temperature characteristic shown in Fig. 7, and the resistance value gradually decreases as the temperature rises. Since it becomes large, it has a function to limit the current. On the other hand Ki1
In the region W1 below the temperature TC, it has a negative temperature coefficient, and the resistance value gradually decreases as the humidity increases, so it has the function of passing a large current, so it can be used as a heater element. Can be used.

Such positive characteristic thermistors are conventionally shown in Figs. 5(a) to (
It is manufactured by the method shown in i).

First, the crystalline resin material containing conductive powder prepared in step (a>) is kneaded in step (b) and then formed into a sheet in step (C). The sheet 1-1 is cross-linked in the step (d) of FIG. 5, and then the sheet 1 is crosslinked in the step (e) as shown in FIG.
Electrodes 2.3 are formed on the front and back surfaces of. Subsequently, in step (f), each unit element is punched out as shown in FIG. 6(C), and then
In step (9), the lead wires 4 and 5 are soldered to the respective electrodes 2 and 3. FIG. 6(d) shows a unit element to which lead wires 4 and 5 are soldered. Furthermore, such a unit element is (
After being painted in the h) process, measurement is performed in the (i) process, and only non-defective thermistors are treated as positive temperature coefficient thermistors.

(Problems to be Solved by the Invention) However, the conventional manufacturing method of a positive temperature coefficient thermistor requires many manufacturing steps, so there is a problem that an increase in manufacturing cost is unavoidable. In particular, the electrode bonding process and the lead attaching process are required separately, which causes an increase in the manufacturing process.

The present invention has been made in response to the above-mentioned problems.
It is an object of the present invention to provide a method for manufacturing a positive temperature coefficient thermistor that simplifies the manufacturing process.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a method of placing a pair of lead wires in a molding die in advance, and then adding conductive powder kneaded into the mold. The mold is fixed by injecting a crystalline resin material containing the mold, and then the mold is removed.

(Function) After a lead wire is placed in a mold in advance, a crystalline resin material containing conductive powder is injected into the mold and solidified. This eliminates the need to perform the electrode contacting process and the c-pue culm with leads separately. Therefore, the manufacturing process can be simplified.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Figures 1 (a> to (f) are block diagrams showing an embodiment of the method for manufacturing a positive temperature coefficient thermistor of the present invention, and will be explained in the order of the steps below. A crystalline resin material containing a commonly used conductive powder is prepared and kneaded in step (b).

Next, in step (C), casting is performed to integrate the crystalline resin material and the lead wire. In this process, first see Figure 2 (
As shown in a), a molding mold 7 equipped with an injection port 6 is prepared, and a pair of lead wires 8 and 9 are arranged in the mold 7 so as to face each other at a desired interval. It is desirable that curved portions 8a, 9a for preventing falling off are formed in advance near the tips of the lead wires 8, 9, for example. Next, as shown in FIG. 2 (b>), the crystalline resin material 11 guided by the guide jig 10 is injected into the mold 7 from the injection port 6 in the direction of the arrow. The pair of lead wires 8 and 9 are covered with a crystalline resin material 11.

Subsequently, after crosslinking is performed in step (d), the mold 7 is removed as shown in FIG. 2(C), and the pair of lead wires 8
, 9 and the crystalline resin material 11 are integrated into a unit element. Next, in step (e), the unit elements are painted, and then in step (f), measurement is performed to select only good products and exclude defective products.

According to the manufacturing method of this embodiment, a mold 7 is prepared, and a pair of lead wires 8 and 9 are placed in advance in the mold 7, and a mold containing conductive powder necessary for manufacturing a positive characteristic nermistor is prepared. Since the crystalline resin material 11 is injected into the mold 7 and integrated with the pair of lead wires 8 and 9 to manufacture the unit device, the electrode adhesion process and lead attaching are performed in the same process as in the past. It is no longer necessary to do both separately; they can be done at the same time. Also, a punching process is not necessary. That is, in this example (
C) Conventional (c) and (e) in Figure 5 depending on the process
, (f), (g>) can be combined. Therefore, the manufacturing process can be simplified, and the manufacturing cost (-) can be reduced. In the positive temperature coefficient thermistor according to this embodiment, the curved portions 3a and 9a are provided in advance on the pair of lead wires 8 and 9 as shown in FIG. 2(C), so the lead wires 8 and 9 are
can be prevented from falling off.

Figure 3 <a> and (b) show lead wires 8 and 9 to prevent them from falling off.
FIG. 3(a) shows a modification of the above, and FIG. 3(a) shows a projection 8b in the middle of a pair of lead wires 8, 9.

9b is shown. Also, Figure 3(b)
There are through holes 8c and 9c in the middle of the pair of lead wires 8 and 9.
By injecting the crystalline resin material 11 into these circulation holes 8c and 9c, it is possible to prevent one drop.

These lead wires 8, 9 can be easily deformed by using ordinary processing techniques, and other deformations other than the shapes described above can also be adopted.

FIGS. 4(a) and 4(b) show another embodiment of the manufacturing method of the present invention, in which multiple pairs of lead wires are arranged as the lead wires applied to the step (C) in FIG. An example is shown below. That is, a molding die 7' equipped with an injection port 6'
is prepared, and a plurality of pairs of lead wires 8A and 9A, 8B and 9B, 8C and 9C, . They are arranged in a bonded state using adhesive paper 13. FIG. 4(b) shows the side shape of multiple pairs of lead wires. According to the manufacturing method of this example, a structure in which a plurality of unit elements are continuous is obtained after crosslinking is performed in step (d) in FIG. do.

According to this embodiment as well, it is not necessary to carry out the electrode bonding process and the lead attaching process separately as in the conventional case, but they can be carried out simultaneously. Therefore, since the manufacturing process can be simplified, the cost can be reduced by 1) as in the previous embodiment.Furthermore, according to this embodiment, multiple unit elements can be molded at the same time by using a common mold. Therefore, the purpose can be achieved with a mold having a simpler structure than that of the previous embodiment.

Further, according to each embodiment of the present invention, since the distance between the pair of lead wires can be arranged wide in advance, there is an advantage that a positive characteristic-Leamister with relatively high resistance can be obtained. Manufacturing of the current limiting element becomes easy.

[Effects of the Invention] As mentioned above, according to the present invention, the lead wire is placed in the mold in advance and then the crystalline resin material is injected into the mold to integrate the two. The manufacturing process can be simplified and assembly costs can be reduced.

[Brief explanation of the drawing]

FIGS. 1(a) to (-f') are block diagrams showing an embodiment of the method for manufacturing a positive temperature coefficient thermistor of the present invention in the order of steps, and FIGS. 2(a) to (C) show the main steps of FIG. 1. The sectional views to be explained, FIGS. 3(a) and 3(b) are sectional views of two main modifications of FIG. 1, and FIGS. 4(a) and (b) are sectional views of other embodiments of the present invention. A cross-sectional view illustrating the main process of μ2, Fig. 5(a)
6(a> to d) are explanatory diagrams of conventional main steps, and FIG. 7 is a resistance-temperature characteristic illustrating a positive temperature coefficient thermistor. 7.7'... Molding jig, 8.8A to 8D, 9.9A to 9D... Lead wire 11... Crystalline resin material, 8a, 9a... Curved portion, 8b, 9b. ··protrusion,
8c, 9c... through holes. Figure (b) Figure (a) Figure

Claims (3)

[Claims] (1) After placing a pair of lead wires in a molding mold in advance, a crystalline resin material containing conductive powder kneaded into the mold is injected to solidify it, and then the mold is removed. A method for manufacturing a characteristic positive temperature coefficient thermistor. (2) The method of manufacturing a positive temperature coefficient thermistor according to claim 1, wherein a plurality of pairs of lead wires are arranged in a molding die. (3) The method for manufacturing a positive temperature coefficient thermistor according to claim 1, wherein a bent portion is provided at the tip of the lead wire to prevent it from falling off.