JP2024058882A - Manufacturing method for temperature detector - Google Patents

Abstract

To provide a method enabling the manufacture of a temperature measuring device that, in addition to having excellent heat resistance and mechanical strength, is capable of contacting a relatively large area with a temperature measuring target and is sufficiently thin, in a relatively simple manner and with a significantly reduced amount of inner insulating synthetic resin compared to conventional methods.SOLUTION: The method for manufacturing a temperature detector with a thermistor chip, a pair of lead wires connected directly to the thermistor chip or via extension wires, and an insulating coating covering at least from the thermistor chip to the connection end of the lead wires includes the steps for coating an insulating thermosetting synthetic resin in an uncured state at least from the thermistor chip to connection ends of the lead wires and pressurizing a pair of sheets in a mutually approaching direction and perpendicular to their planes and heating the thermosetting synthetic resin by interposing, after the coating step, at least from the thermosetting synthetic resin-coated thermistor chip to the connection ends of the lead wires between the pair of insulating synthetic resin sheets.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a temperature detector, and more specifically, to a method for manufacturing a temperature detector having a thermistor chip, a pair of lead wires connected to the thermistor chip directly or via a lead wire, and an insulating coating that covers at least the thermistor chip to the connection end of the lead wires.

As is well known to those skilled in the art, temperature detectors having a thermistor chip, a pair of lead wires connected to the thermistor chip directly or via a lead wire, and an insulating coating covering at least the thermistor chip to the connection end of the lead wires are widely used. When such a temperature detector is used as a temperature detector for a secondary battery mounted in an automobile, for example, it is desired that the temperature detector has excellent heat resistance and mechanical strength, and that it can contact the object to be measured over a relatively wide area and is sufficiently thin. The following Patent Document 1 discloses a method for manufacturing a temperature detector that satisfies such requirements, in which the thermistor chip, a pair of lead wires connected to the thermistor chip via a lead wire, and at least the thermistor chip to the connection end of the lead wires are disposed between a pair of inner insulating synthetic resin sheets and a pair of outer insulating synthetic resin sheets, and the pair of inner insulating synthetic resin sheets and the pair of outer insulating synthetic resin sheets are pressurized and heated in a direction approaching each other and perpendicular to their planes. Each of the pair of inner insulating synthetic resin sheets is made of fluorinated ethylene propylene, which is a fluorine-based synthetic resin with a relatively low melting point, and each of the pair of outer insulating synthetic resin sheets is made of polytetrafluoroethylene, which is a fluorine-based synthetic resin with a relatively high melting point. The pair of inner synthetic resin sheets and the pair of outer synthetic resin sheets each have a rectangular planar shape and have the same dimensions and planar shape. Heating is performed at a temperature higher than the melting point of fluorinated ethylene propylene but lower than the melting point of polytetrafluoroethylene, so that the pair of outer insulating synthetic resin sheets do not melt, but the pair of inner insulating synthetic resin sheets melt and then harden. After melting and hardening, the inner insulating synthetic resin sheet and the outer insulating synthetic resin sheet form an insulating coating.

Republished Patent WO2019/087755

The method disclosed in the above-mentioned Patent Document 1 has the following problems to be solved: (1) it is necessary to position the pair of outer insulating synthetic resin sheets together with the pair of inner insulating synthetic resin sheets with sufficient precision when applying pressure and heat, which makes the operation complicated; and (2) the use of the pair of inner insulating synthetic resin sheets results in the amount of inner insulating synthetic resin used being greater than necessary, which increases the manufacturing cost.

The present invention was made in consideration of the above facts, and its main technical objective is to provide a new and improved method that makes it possible to manufacture a temperature measuring device that is excellent in heat resistance and mechanical strength, and that is thin enough to contact the object to be measured over a relatively wide area, in a relatively easy manner and with a significantly reduced amount of inner insulating synthetic resin used compared to conventional methods.

As a result of extensive research and experimentation, the inventors have found that the above-mentioned main technical objective can be achieved by applying uncured insulating thermosetting synthetic resin at least from the thermistor chip to the connection end of the lead wire, and then placing at least the area from the thermistor chip to the connection end of the lead wire to which the thermosetting synthetic resin has been applied between a pair of insulating synthetic resin sheets, and applying pressure to the pair of sheets in a direction in which they approach each other and in a direction perpendicular to their planes while heating the thermosetting synthetic resin.

That is, according to the present invention, a method for achieving the above-mentioned main technical object is as follows:
A method for manufacturing a temperature detector including a thermistor chip, a pair of lead wires connected to the thermistor chip directly or via a lead wire, and an insulating coating covering at least an area extending from the thermistor chip to a connection end of the lead wires, comprising the steps of:
a coating step of coating an uncured insulating thermosetting synthetic resin at least from the thermistor chip to the connection end of the lead wire;
a pressurizing and heating step of, after the application step, placing at least the thermistor chip coated with the thermosetting synthetic resin to the connection end of the lead wire between a pair of insulating synthetic resin sheets, and pressurizing the pair of sheets in a direction in which they approach each other and in a direction perpendicular to their planes while heating the thermosetting synthetic resin;
A method is provided comprising:

Preferably, in the coating step, at least the thermistor chip to the connection end of the lead wire is immersed in uncured thermosetting synthetic resin, and then removed from the thermosetting synthetic resin, thereby coating at least the thermistor chip to the connection end of the lead wire with thermosetting synthetic resin. The thermosetting synthetic resin is preferably an epoxy-based synthetic resin mixed with silica particles to impart thixotropy. Each of the pair of sheets is preferably a polycarbonate-based synthetic resin sheet. Preferably, each of the pair of sheets has a thickness of 0.1 to 0.8 mm. It is convenient for each of the pair of sheets to have a rectangular planar shape.

In the method of the present invention, instead of using a pair of inner insulating synthetic resin sheets, uncured thermosetting synthetic resin is applied at least from the thermistor chip to the connection end of the lead wire, making it possible to manufacture a temperature detector relatively easily and with a significantly reduced amount of inner insulating synthetic resin used compared to conventional methods.

FIG. 2 is a perspective view showing a thermistor chip used in the method of the present invention and a pair of lead wires connected to the thermistor chip via lead wires. FIG. 2 is a perspective view showing the thermistor chip shown in FIG. 1 and a state in which an insulating thermosetting synthetic resin is applied to connection ends of a pair of lead wires connected to the thermistor chip via lead wires. FIG. 2 is a front view showing a state in which a thermistor chip coated with a thermosetting synthetic resin and connection ends of a pair of lead wires connected to the thermistor chip via lead wires are positioned between a pair of insulating synthetic resin sheets. FIG. 1 is a front view showing a state in which a pair of insulating synthetic resin sheets are pressed in a direction in which they approach each other and in a direction perpendicular to their planes, and the thermosetting synthetic resin is heated. 1 is a perspective view of a temperature measuring device manufactured by a preferred embodiment of the method of the present invention;

The method of the present invention will now be described in more detail with reference to the accompanying drawings, which show a preferred embodiment of the method.

Preparation of thermistor and lead wires connected to thermistor Referring to FIG. 1, in a preferred embodiment of the method of the present invention, first, a thermistor chip 2 and a pair of lead wires 6a and 6b connected to the thermistor chip 2 via lead wires 4a and 4b are prepared. The illustrated thermistor chip 2 is composed of a thermistor, an element electrode layer laminated on both surfaces of the thermistor, and a cover electrode layer laminated on the element electrode layer, although not shown. Such a thermistor chip 2 itself is a well-known form and is described, for example, in JP-A-2020-21861, so its details will not be described in this specification. The tips of a pair of lead wires 4a and 4b are connected to the thermistor chip 2 by appropriate connecting means such as welding or soldering, and the tips of the lead wires 6a and 6b are connected to the rear ends of the lead wires 4a and 4b by appropriate connecting means such as welding or soldering. The lead wires 4a and 4b may be made of copper-nickel alloy wire, and the lead wires 6a and 6b may be made of a core material made of multiple twisted copper wires and a coating made of insulating synthetic resin covering the core material. The coating is removed from the tip end, i.e., the connection end, of the lead wires 6a and 6b, and the core material is connected to the lead wires 4a and 4b. In the illustrated embodiment, the thermistor elements to which the tip ends of the lead wires 4a and 4b are connected are further sealed with glass.

In the illustrated embodiment, the lead wires 6a and 6b are connected to the thermistor element via the lead wires 4a and 4b, but the method of the present invention can also be applied to a configuration in which the lead wires 6a and 6b are directly connected to the thermistor element.

Next, in the method of the present invention, as shown in Fig. 2, at least the thermistor chip 2, the lead wires 4a and 4b, and the connection ends of the lead wires 6a and 6b, i.e., at least from the thermistor chip 2 to the connection ends of the lead wires 6a and 6b, are coated with the insulating thermosetting synthetic resin 8. Such coating can be suitably carried out by dip coating, that is, by immersing the thermistor chip 2 to the connection ends of the lead wires 6a and 6b (including the connection ends from which the coating has been removed and the adjacent portions of the lead wires 6a and 6b where the coating is present) in the insulating thermosetting synthetic resin in an uncured state, and then removing them from the thermosetting synthetic resin. The amount of the thermosetting synthetic resin applied can be appropriately adjusted by adjusting the speed at which the thermistor chip 2 to the connection ends of the lead wires 6a and 6b (and the adjacent portions of the lead wires 6a and 6b where the coating is present) are removed from the thermosetting synthetic resin. When the thermosetting synthetic resin is taken out from the thermistor chip 2 to the connection ends of the lead wires 6a and 6b (and the adjacent portions where the coating of the lead wires 6a and 6b is present) at a relatively slow speed, a relatively large amount of thermosetting synthetic resin can be applied, and when it is taken out at a relatively high speed, a relatively small amount of thermosetting synthetic resin can be applied. As for the amount of application of the thermosetting synthetic resin, it is preferable that the thermosetting synthetic resin 8 is not present over the entire surface of the pair of insulating synthetic resin sheets described later, but is present only in the center of the pair of insulating synthetic resin sheets, and that the amount of application of the thermosetting synthetic resin is approximately such that the thermosetting synthetic resin 8 substantially surrounds the connection ends of the thermistor chip 2 to the connection ends of the lead wires 6a and 6b (and the adjacent portions where the coating of the lead wires 6a and 6b is present). As a suitable example of the thermosetting synthetic resin to be applied, there can be mentioned an epoxy-based synthetic resin mixed with silica particles to impart thixotropy to a thixotropy index of about 3.0 to 3.9.

If desired, instead of applying the thermosetting synthetic resin 8 by dip coating, a suitable applicator such as a paintbrush can be used to apply the uncured thermosetting synthetic resin from the thermistor chip 2 to the connection ends of the leads 6a and 6b (and the adjacent portions of the leads 6a and 6b where the coating is present).

Pressurizing and Heating Step After the above-mentioned coating step, in the method of the present invention, the thermistor chip 2 to the connection ends of the lead wires 6a and 6b (and the adjacent portions of the lead wires 6a and 6b where the coating is present) are interposed between a pair of insulating synthetic resin sheets 10a and 10b, and the pair of sheets 10a and 10b are pressed in a direction in which they approach each other and in a direction perpendicular to their planes, while the thermosetting synthetic resin applied as described above is heated and hardened. To explain a preferred form of such pressurizing and heating step, first, as shown in Figure 3, the insulating synthetic resin sheet 10b is placed on a suitable stationary support 12, and then the thermistor chip 2 to the connection ends of the lead wires 6a and 6b (and the adjacent portions of the lead wires 6a and 6b where the coating is present) where the thermosetting synthetic resin 8 is applied are placed on the insulating synthetic resin sheet 10b, and then the insulating synthetic resin sheet 10a is further laminated. 4, the movable pressure table 14 is lowered onto the insulating synthetic resin sheet 10a, and the sheets 10a and 10b are pressed between the stationary support table 12 and the movable pressure table 14 in a direction in which they approach each other and in a direction perpendicular to their planes. At the same time, the sheets 10a and/or 10b, as well as the thermosetting synthetic resin 8 located therebetween, are heated via the movable pressure table 14 and/or the stationary support table 12. The heating temperature must be sufficiently lower than the melting temperature of the sheets 10a and 10b (and therefore does not adversely affect the sheets 10a and 10b) but sufficient to harden the thermosetting resin 8. Thus, the thermosetting synthetic resin 8 is flattened to reduce the thickness between the sheets 10a and 10b to a required value, which may be about 0.5 to 2.0 mm, and the thermosetting synthetic resin 8 is hardened, thereby manufacturing the temperature detector. The thermosetting synthetic resin 8 and the insulating synthetic resin sheets 10a and 10b constitute an insulating coating from the thermistor chip 2 to the connection ends of the lead wires 6a and 6b (and the adjacent portions of the lead wires 6a and 6b where the coating is present). If desired, instead of heating the thermosetting synthetic resin 8 via the movable pressure table 14 and/or the stationary support table 12 and the sheets 10a and/or 10b, the thermosetting synthetic resin 8 can also be directly heated by a suitable heating method that acts directly on the thermosetting synthetic resin 8.

A suitable example of the insulating synthetic resin sheets 10a and 10b is a polycarbonate-based resin sheet that has excellent mechanical properties as well as insulating properties, and is preferably transparent or semi-transparent. The thickness of each of the insulating synthetic resin sheets 10a and 10b is preferably about 0.1 to 0.8 mm. In addition, the planar shape of each of the insulating synthetic resin sheets 10a and 10b is rectangular, and the planar dimensions may be about 7.0 to 15.0 x 15.0 to 30.0 mm. It is preferable that the insulating synthetic resin sheets 10a and 10b are substantially identical.

Figure 5 illustrates the final product, i.e., a temperature detector, manufactured by a preferred embodiment of the method of the present invention. The thermistor chip 2 to the connection ends of the lead wires 6a and 6b (and the adjacent portions of the lead wires 6a and 6b where the coating is present) are surrounded by a thermosetting synthetic resin 8, and are further covered by a pair of insulating synthetic resin sheets 10a and 10b. It is not necessary that the entire area from the thermistor chip 2 to the connection ends of the lead wires 6a and 6b be surrounded by the thermosetting synthetic resin 8, and since it is covered by a pair of insulating synthetic resin sheets 10a and 10b, even if a portion from the thermistor chip 2 to the connection ends of the lead wires 6a and 6b is locally exposed without being surrounded by the thermosetting synthetic resin 8, no particular problem will occur depending on the environment in which the temperature detector is used.

2: Thermistor chip 4a: Lead wire 4b: Lead wire 6a: Lead wire 6b: Lead wire 8: Thermosetting synthetic resin 10a: Insulating synthetic resin sheet 10b: Insulating synthetic resin sheet 12: Stationary support 14: Movable pressure table

Claims (6)

A method for manufacturing a temperature detector including a thermistor chip, a pair of lead wires connected to the thermistor chip directly or via a lead wire, and an insulating coating covering at least an area extending from the thermistor chip to a connection end of the lead wires, comprising the steps of:
a coating step of coating an uncured insulating thermosetting synthetic resin at least from the thermistor chip to the connection end of the lead wire;
a pressurizing and heating step of, after the application step, placing at least the thermistor chip coated with the thermosetting synthetic resin to the connection end of the lead wire between a pair of insulating synthetic resin sheets, pressurizing the pair of sheets in a direction in which they approach each other and in a direction perpendicular to their planes, and heating the thermosetting synthetic resin;
The method according to claim 1, further comprising: The method according to claim 1, wherein in the coating step, the thermosetting synthetic resin is coated at least from the thermistor chip to the connection end of the lead wire by immersing the area from the thermistor chip to the connection end of the lead wire in uncured thermosetting synthetic resin and then removing the area from the thermosetting synthetic resin. The method according to claim 1 or 2, wherein the thermosetting synthetic resin is an epoxy-based synthetic resin to which silica particles have been mixed to impart thixotropy. The method according to claim 1, wherein each of the pair of sheets is a polycarbonate-based synthetic resin sheet. The method of claim 1 or 4, wherein each of the pair of sheets has a thickness of 0.1 to 0.8 mm. 5. The method according to claim 1 or 4, wherein the planar shape of each of the pair of sheets is rectangular.

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