JPH10270208A - Thermistor temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly durable thermistor temperature sensor which has less characteristic variations and can be manufactured at a low cost. SOLUTION: A thermistor temperature sensor is formed by inserting a chip- type thermistor element 8 connected with insulated covered wires 5 into a protective case 6 and molding the case 6 with a resin 9. On the thermistor element 8, insulating coating films 10 composed of glass of a high polymer material (for example, an epoxy) are formed on the side faces of a rectangular parallelepiped thermistor blank body 9 which are elongated in the length direction and electrode layers 11 are formed on the pair of the end faces of the blank body 9, separated from each other in the length direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor temperature sensor used for an air conditioner, a refrigerator and the like.

[0002]

2. Description of the Related Art As a thermistor temperature sensor, FIG.
As shown in (a) to (d), the disk-type thermistor element 1, the flake-type thermistor element 2, the radial-lead-type glass-filled thermistor element 3, the axial-lead-type glass-filled thermistor element 4, etc. Are inserted into a protective case 6 made of metal or resin and molded with a resin 7.

[0003]

[Problems to be solved by the invention]

I. The thermistor temperature sensor using the disk-type thermistor element and the flake-type thermistor element has a low thermistor element cost, but has the following problems.

Since the thermistor element between the electrodes is exposed, the characteristics are likely to be degraded due to corrosion due to water intrusion into the element or an interface between the element and the electrode. Further, since the electrode containing silver is exposed on the element surface, migration of silver is likely to occur. As a measure to prevent migration, it is effective to plate a metal that hardly causes migration on the electrode surface containing silver, but the thermistor body is eroded by the plating solution. Forming an insulating material film such as a glass film on the surface of the exposed element is effective in increasing reliability, but disk-type thermistor elements and flake-type thermistor elements are inexpensive at practical costs. Is difficult to form. Since the disk-type thermistor element is manufactured by the powder press molding method, the dimensional variation is large, and therefore, the thermistor resistance value is large.

II. A thermistor temperature sensor using a radial lead type or axial lead type element has a problem that the element cost is high.

III. An object of the present invention is to provide a thermistor temperature sensor which solves such various problems, has good durability, has small characteristic variations, and is inexpensive to manufacture.

[0007]

A thermistor temperature sensor according to the present invention comprises a thermistor element and a lead wire connected to the thermistor element, wherein the thermistor element is formed by resin coating or resin molding. The present invention is characterized in that a chip-type thermistor element having a terminal electrode formed at an end in a longitudinal direction of a rectangular parallelepiped is used as the thermistor element.

The chip type thermistor element employed in the present invention is manufactured in a uniform shape and size for surface mounting. Therefore, the automatic machine can be easily used in the assembly process of the sensor, and the assembly cost can be reduced. Further, since the chip-type thermistor element is cut and formed, for example, from a wafer obtained by slicing a fired block, the dimensional accuracy is higher than that of a disk-type thermistor element, and thus the variation in resistance value is small.

This chip-type thermistor element can be coated at a practical cost by a screen printing method or the like at a rod-like stage after the wafer is cut. (The insulating coat is preferably an inorganic substance such as glass, but may be a polymer material such as an epoxy or the like.) The insulating coat can prevent corrosion of the element body due to a plating solution, and therefore, an electrode containing silver can be used. It is possible to plate a metal such as nickel which is unlikely to cause migration on the surface. Further, formation of the insulating coat can prevent water from entering the element body.

As another method of manufacturing the chip type thermistor element, there is a method in which a thermistor powder material is formed into a sheet, the sheets are stacked, cut into chips, and fired. Is disadvantageous in that it is difficult to form an insulating coat;

In the present invention, it is preferable that the chip type thermistor element uses AgPd for the base electrode and has a Pd of 20% or more. In this case, as the electrode material, an electrode paste (metal powder material, glass frit and organic solvent) on which an electrode is formed by sintering, or a conductive resin paste (metal powder material, resin and Organic solvent) can be used.

According to the present invention, if the resistance adjusting electrode is formed on the thermistor element, the shape is constant and the resistance value can be freely adjusted with high precision.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as shown in FIG.
A chip thermistor element 8 is used as the thermistor element. FIG. 1B is a perspective view of the chip thermistor element 8, and FIG. 1C is a schematic sectional view of the chip thermistor element 8.

The chip-type thermistor element 8 has a rectangular parallelepiped thermistor element 9 formed on a side surface extending in the longitudinal direction with an insulating coat 10 made of glass or a polymer material (for example, epoxy). The terminal electrode 11 is formed on the end face of the substrate.

The terminal electrode 11 includes a base electrode 12, a nickel (Ni) plating 13 covering the base electrode 12, and a solder plating 14 covering the nickel plating 13.

The base electrode 12 has a Pd content of 20.
% (For example, 20 to 50%) of AgPd is preferably used. In addition, migration of Ag can be prevented by the Ni plating 13. Cr plating may be adopted instead of Ni plating.

The insulated wire 5 is connected to the chip type thermistor element 8 and inserted into a protective case 6 made of metal (for example, SUS, copper) or resin (for example, epoxy, ABS, PBT, etc.), and the resin 9 is molded. , A thermistor temperature sensor is formed.

Instead of the chip-type thermistor element 8 shown in FIG. 1C, chip-type thermistor elements 8A and 8 having resistance adjusting electrodes shown in FIGS. 1D, 1E and 1F.
B, 8C may be used. Chip type thermistor element 8A
Is provided with a resistance adjusting electrode 15 on a side surface extending in the longitudinal direction of the thermistor element body 9. The chip type thermistor elements 8B and 8C are provided with resistance adjusting electrodes 16 extending in the longitudinal direction inside the thermistor element body 9. 17 is provided.
It is preferable that the chip type thermistor element 8A is provided with the insulating coat 10 so as to cover the resistance adjusting electrode 15. In the chip thermistor element 8B, the insulation is omitted because the resistance adjusting electrode is not exposed. However, in order to further improve the reliability, the insulating coat 10 is formed on the element body surface like the chip thermistor element 8C. It is desirable.

[0019]

As described above, the thermistor temperature sensor of the present invention uses a chip-type thermistor element as the thermistor element, and has a low assembling cost, a small variation in sensor characteristics, and a high durability (in particular, water resistance). sex)
Is good.

[Brief description of the drawings]

1A is a cross-sectional view of a thermistor temperature sensor according to an embodiment, FIG. 1B is a perspective view of a chip-type thermistor element, and FIGS. 1C, 1D, 1E, and 1F are respectively; It is sectional drawing of a chip type thermistor element.

FIG. 2 is a cross-sectional view of a conventional thermistor temperature sensor.

[Explanation of symbols]

 Reference Signs List 5 Insulated wire 6 Protective case 7 Mold resin 8, 8A, 8B, 8C Chip thermistor element 9 Thermistor element 10 Insulating coat 11 Terminal electrode 12 Base electrode 13 Ni plating 14 Solder plating

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaki Koshimura 2270 Yokoze, Yokoze-cho, Chichibu-gun, Saitama Pref.

Claims (6)

[Claims] 1. A thermistor temperature sensor comprising a thermistor element and a lead wire connected to the thermistor element, wherein the thermistor element is resin-coated or resin-molded. A thermistor temperature sensor using a chip-type thermistor element having terminal electrodes formed thereon. 2. The terminal according to claim 1, wherein the terminal electrode of the thermistor element has a base electrode containing silver and a surface plating layer covering the base electrode, and the surface plating layer causes migration of nickel or the like. A thermistor temperature sensor comprising a difficult layer. 3. The chip thermistor element according to claim 1, wherein the metal contained in the base electrode of the terminal electrode is AgPd and Pd is 20% or more as the chip thermistor element. Thermistor temperature sensor. 4. The thermistor temperature sensor according to claim 1, wherein the surface of the rectangular parallelepiped chip type thermistor element other than the terminal electrodes is covered with an insulating material. 5. The thermistor temperature sensor according to claim 1, wherein an electrode for adjusting a resistance is formed inside the rectangular parallelepiped chip thermistor element. 6. The thermistor according to claim 4, wherein an electrode for resistance adjustment is formed on a surface of the element body other than the terminal electrode, and surfaces other than the terminal electrode including the resistance adjustment electrode are covered with an insulating material. A thermistor temperature sensor using an element.