JPH09178571A - Thermistor and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the waterproofness and moisture resistance of a glass sealed thermistor. SOLUTION: A glass beads 1 encapsulating a thermistor element 2 is combined with a tubular body 4 inserted with both lead wires 3, 3 of thermistor led out from the glass beads 1. A heat resistant, moisture resistant and chemical resistant resin coating 5 is then applied onto the entire surface of glass beads 1, a part of both lead wires 3, 3 exposed between the glass beads 1 and the tubular body 4 and the end face on the inserting side of lead wires 3, 3 including the circumferential surface at the drum part thereof. Furthermore, the coating resin 5 permeates into the holes 6 of tubular body 4 and cured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor sensor which is effective mainly for measuring hot water temperature, oil temperature, steam temperature, and gas temperature, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A thermistor temperature sensor, which is inserted in hot water or oil or exposed to high-temperature gas or steam to measure liquid temperature and gas temperature, is required to have moisture resistance and chemical resistance.

A glass-sealed thermistor has been known as a waterproof thermistor, and further, a lead wire drawn out from the glass-sealed thermistor is covered with a coating tube, which is housed in a metal protective tube having a bottom. There is known a structure in which an electrical insulating material such as epoxy resin is filled and sealed. The glass-sealed thermistor is a glass thermistor element sealed in a glass bead.The lead wire pulled out from the glass bead is protected by a coating tube, and the whole is isolated from the environment in which the thermistor sensor is used by a protective tube. It has a waterproof structure. However, according to Japanese Utility Model Application Laid-Open No. 5-79902, in the thermistor sensor having the above structure, when the cyclical change of temperature is constantly repeated in a high humidity atmosphere, the filling resin inside the protective tube, the metal protective tube, the coated tube, Pointing out the disadvantage that the adhesion between glass beads deteriorates and water easily enters inside,
In order to eliminate this drawback, the lead portions of the thermistor element 11 and the lead wire 12 are melted into a glass sealing body (glass beads) 13 as shown in FIG. 5, and the glass sealing body 13 and the fine ceramics, tempered glass or the like are used. An attempt has been proposed to prevent the electrical corrosion of the lead wire 12 due to moisture by fusion-bonding the ceramic body 14 together.

[0004]

In the above-mentioned prior art, the method of fusion-bonding the glass sealing body 13 and the ceramic body 14 is not clear, but it is possible that the glass sealing body 13 and the ceramic body 14 are probably in a molten state. It seems that they will be pressed and then solidified and integrated. Although it is possible to adhere molten glass to ceramics more firmly, it is not clear whether the ceramic body secures the adhesion of all contact surfaces in the fused and sealed glass encapsulant. I can't.

If a gap is formed between the glass sealing body and the ceramic body, water may enter to cause electrical corrosion, or lead wires may be broken or a short circuit between lead wires may occur. .

For example, even if the adhesion between the outer peripheral portion of the ceramic body and the glass sealing body is ensured, water may intrude through the lead wire holes of the ceramic body, and the moisture intrudes from both outer peripheral portions. It doesn't have to be able to prevent.

Further, when a low melting point glass is used for the thermistor element sealing glass of a thermistor used in a high humidity atmosphere such as steam, a part of the glass sealing body is dissolved in water to form a ceramic body. When the thermistor peels off the adhesion from the glass encapsulant, and the lead wire of the thermistor that is immersed in oil is incompletely sealed and the usage time is several hundred hours, sulfur in the oil Reacts with the copper component of the lead wire to deposit sulfur sulfide, which causes insulation failure between lead wires or occurrence of a short circuit accident.

An object of the present invention is to provide a thermistor and a method for manufacturing the thermistor, in which the lead wires of the glass-sealed thermistor are completely shielded from the external environment so that insulation failure of the lead wires or short circuit between the lead wires does not occur. It is in.

[0009]

In order to achieve the above object, in a thermistor according to the present invention, a thermistor having a thermistor element sealed in glass beads, a tubular body, and a coating resin is provided. The body is a ceramic cylinder, which has two holes that penetrate the entire length, and the two lead wires of the thermistor element that are pulled out from the glass beads are individually inserted into the holes of the cylinder and covered. The resin is applied across the glass beads and a part of the cylindrical body, and covers the entire surface of the glass beads, the lead wire portion between the glass beads and the cylindrical body, and a part of the cylindrical body. It penetrates into the holes through which the wires are inserted and solidifies.

Further, in the method of manufacturing a thermistor according to the present invention, there is provided a method of manufacturing a thermistor in which the thermistor is sealed with a resin, the method including a through treatment, a dipping treatment, and a curing treatment. The glass beads are sealed and have two lead wires pulled out from the glass beads, and the insertion process is a process of inserting the lead wires of the thermistor into the cylinder, and the cylinder is ceramics,
It has two independent holes in the length direction, two lead wires of the thermistor are individually inserted into each hole of the cylinder, and the dipping treatment is a treatment for coating the glass beads and a part of the cylinder with resin. And consists of a glass bead coating process and a cylindrical body coating process,
The glass bead coating treatment is a treatment in which the glass beads are immersed in a molten resin to deposit the resin on the entire surface of the glass beads, and the tubular body coating treatment is performed by immersing the tubular body together with the glass beads in a molten resin liquid. , Is a process of depositing resin on the end face of the tubular body and a part of its outer periphery over a certain range in the length direction from the end face of the tubular body. In this state, the glass beads and the resin adhered to a part of the cylindrical body are integrated and solidified.

Further, in the tubular body coating treatment, when the tubular body is immersed in the molten resin, the resin is received in the hole of the tubular body through which the lead wire of the thermistor element is inserted, and the tubular body is made to utilize the capillary phenomenon. The process of filling the resin in the holes of a certain height range is included.

The hardening treatment is a heating reaction treatment of the adhered resin, and includes a treatment of infiltrating and filling the resin softened by heating into the holes of the cylindrical body.

In the present invention, the entire surface of the glass beads for sealing the thermistor element and the end face of the tubular body through which both the lead wires drawn from the glass bead are inserted are resin-sealed to provide a space between the glass beads and the tubular body. The lead wire exposed at the end is also resin-coated and completely isolated from the external environment.

In the cylindrical body coating process, if the coating resin is deeply filled into the hole of the cylindrical body, moisture or the like can be prevented from entering from the end face of the cylindrical body into the hole, and the lead inserted into the hole of the cylindrical body. The wire is covered with a coating resin to improve water resistance and moisture resistance.

When the glass-sealed thermistor is planned to be used in a temperature environment of 300 ° C. or lower, a polyamide resin is used as the coating resin.
When used in a high temperature environment, the coating resin is required to have higher heat resistance. The coating resin suitable for use in a high temperature environment of 300 ° C. to 400 ° C. includes, for example, heat-resistant cement (eg, Daimo Mach (trade name) Topy S-200).
2) is preferred.

The coating thickness of the coating resin is about 0.1 mm, 3 when used at a temperature of 300 ° C. or less.
0.3-for those used at temperatures over 00 ° C
0.5 mm is necessary.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the glass coat type thermistor of the present invention. In the thermistor according to the present invention, the two lead wires 3 and 3 of the thermistor element 2 sealed in the glass beads 1 are inserted into the cylindrical body 4 so as to cover the entire surface of the glass beads and the cylindrical resin 4. 5 is attached.

The coating resin 5 covers the entire surface of the glass beads 1 and the thermistor element 2 pulled out from the glass beads 1.
The lead wires 3 and 3 are attached to the open end face of the hole 6 and a part of the peripheral surface of the body, including the lead-out portions of the lead wires 3 and 3 and the hole 6 of the cylinder 4 into which the lead wires 3 and 3 are inserted.

The tubular body 4 is a ceramic tubular body made of fine ceramics, tempered glass or the like, has two holes 6 and 6 penetrating the entire length thereof, and has two lead wires 3 of the thermistor element 2. 3 is individually inserted into each hole 6 from one opening end surface of the tubular body 4, and is drawn out from the other opening end.

The coating resin 5 is a resin having excellent heat resistance, moisture resistance and chemical resistance, for example, a polyamide resin, and when high temperature heat resistance is required, moisture resistant cement is used.

Next, a method of manufacturing the thermistor of the present invention will be described in the order of steps.

(1) Insertion processing step In FIG. 2 (a), the lead wires 3 and 3 of the thermistor element 2 are inserted into the tubular body 4, and the spacing between the tubular body 4 and the glass beads 1 is set to a predetermined interval. The thermistor element 2 is held in the tubular body 4 by holding it, and the tubular body 4 is vertically attached to the holder 7 to suspend the glass beads 1 downward.

(2) Immersion treatment (glass bead coating treatment)
Process In FIG. 2B, the holder 7 is lowered, and the entire glass beads 1 are immersed in the molten resin 5a of the coating resin 5 filled in the dip tank 8.

(3) Immersion Treatment (Cylinder Covering) Step In FIG. 2 (b), the holder 7 is further lowered and a part of the body of the cylinder 4 is immersed in the molten resin 5a in the dip tank 8. Then, the glass beads 1 are pulled up from the dip tank 8. At the time of pulling up, the molten resin 5a is first pulled up quickly so that the molten resin remains between the lead wires 3 and 3, and then the amount of the molten resin 5a attached to the surface of the glass beads 1 is increased. The molten resin 5a is slowly pulled up to reduce the amount of the molten resin 5a, and the entire surface of the glass beads 1, the surfaces of both lead wires 3 and 3 drawn from the glass beads 1, and the end surface of the tubular body 4 are partially covered. It is attached over the entire area. When the molten resin 5a is not sufficiently adhered between the lead wires 3 and 3 in the above series of treatments, the covering resin 5 adhered between the lead wires 3 and 3 and the covering resin 5 adhered to the cylindrical body are completely removed. Connect to glass beads 1
The above series of steps is repeated until the space between the cylindrical body 4 and the cylindrical body 4 is completely covered without a gap.

(4) Curing Treatment Step In FIG. 3, the molten resin 5a applied between the glass beads 1 and the cylindrical body 4 is air-dried, temporarily dried, and then finally dried to be solidified.

In the present invention, when the tubular body 4 is immersed in the molten resin 5a during the dipping treatment (cylindrical coating treatment) step, the molten resin 5a penetrates into the hole 6 of the tubular body 4 to the immersion depth. However, as shown in FIG. 4, the molten resin can be permeated deeply into each hole 6 of the cylindrical body 4 at a height of 3 to 5 mm above the liquid surface by a capillary phenomenon.

When a polyamide resin is used as the coating resin, temporary drying is carried out at 105 ° C. for 60 minutes and main drying is carried out for 20 minutes.
The coating resin 5 is solidified by heating at 0 ° C. for 60 minutes, but before the coating resin 5 is heated and hardened, the coating resin 5 once softens and expands into the holes 6 of the cylindrical body 4, so that the coating resin 5 expands. Hole 6
The coating resin 5 can penetrate deeper into the inside.

As described above, FIG. 2 shows an example in which the glass beads 1 and the cylindrical body 4 are spaced apart from each other and the lead wire is exposed for a long time in order to make the explanation easy to understand. In many cases, as shown in FIG. 1, the glass beads 1 and the cylindrical body 4 are substantially brought into contact with each other. Even in this case, the glass beads 1 and the cylindrical body are first immersed in the molten resin 5a by the two-step immersion treatment, and then the cylindrical body 4 is immersed in the molten resin 5a. It is possible to avoid a situation in which bubbles are trapped between the four.

[0030]

According to the present invention, the entire surface of the glass beads, the portion of the lead wire connecting between the glass beads and the cylinder, and the end surface of the cylinder are covered with a coating resin, and the lead wire is inserted. Since the coating resin is deeply dipped into each hole, the insulation between the lead wires, heat resistance, water resistance, moisture resistance, and chemical resistance are improved, and the temperature of the automotive mission oil measurement sensor, water heater, or microwave oven is improved. It can be used in applications such as measurement hermetic sensors to improve its reliability.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

2 (a) to (c) are views showing a manufacturing process of the thermistor of the present invention in process order.

FIG. 3 is a diagram showing a state in which a coating resin is adhered by a curing treatment.

FIG. 4 is a diagram showing a state in which molten resin permeates into the holes of the cylinder by the dipping treatment.

FIG. 5 is a diagram showing an example of a conventional waterproof / moisture-proof thermistor sensor.

[Explanation of symbols]

 1 Glass Bead 2 Thermistor Element 3 Lead Wire 4 Cylindrical Body 5 Covering Resin 6 Hole 7 Holder 8 Dip Tank

Claims (4)

[Claims] 1. A thermistor having a thermistor element sealed in glass beads, a tubular body, and a coating resin, the tubular body being a ceramic tube having two holes penetrating its entire length. The two lead wires of the thermistor element, which are pulled out from the glass beads, are individually inserted into the holes of the cylindrical body, and the coating resin is applied across the glass beads and a part of the cylindrical body. It is characterized by covering the entire surface of the glass beads, the lead wire portion between the glass beads and the cylinder, and a part of the cylinder, and further penetrating into the hole through which the lead wire is inserted and solidified. And the thermistor. 2. A method of manufacturing a thermistor, which comprises an insertion process, a dipping process, and a hardening process, wherein the thermistor is resin-sealed, wherein the thermistor element is sealed in a glass bead, and the glass bead is sealed. With the two lead wires pulled out, the insertion process is the process of inserting the lead wire of the thermistor into the cylinder. The cylinder is ceramics and has two independent holes in the length direction. The two lead wires of the thermistor are individually inserted into each hole of the cylindrical body, and the dipping treatment is a resin coating of the glass beads and a part of the cylindrical body. The glass bead coating process is a process in which the glass beads are immersed in a molten resin to deposit the resin on the entire surface of the glass beads. Is a process of applying resin to the end face of the tubular body and a part of its outer periphery over a certain range in the length direction from the end face of the tubular body. A method of manufacturing a thermistor, characterized in that the thermistor is a process in which the glass beads and the resin adhered to a part of the cylindrical body are integrated and solidified in a state of being filled. 3. The tubular body coating treatment, when the tubular body is immersed in a molten resin, receives the resin in the hole of the tubular body through which the lead wire of the thermistor element is inserted, and utilizes the capillary phenomenon to take advantage of the tubular body. 3. The method for manufacturing a thermistor according to claim 2, further comprising the step of filling the hole with the resin over a range of a certain height. 4. The curing treatment is a heating reaction treatment of a resin to be adhered, which includes a treatment of infiltrating and filling the resin softened by heating into the holes of the cylindrical body. 3. The method for manufacturing the thermistor according to item 3.