CN209607522U - A Linear PTC Thermistor - Google Patents

Abstract

The utility model discloses a kind of linear PTC thermal resistors; including substrate; substrate upper surface middle position is equipped with resistor layer; protective film is equipped with above the resistor layer; it is equipped with face electrode at left and right sides of the resistor layer, is equipped with back electrode at left and right sides of the substrate lower end surface, the substrate, face electrode and back electrode are wrapped with internal electrode; the internal electrode is wrapped with target, and the target is wrapped with external electrode.The utility model compared with prior art the advantages of be: good linearity, stability is good, small in size, light-weight, long service life.

Description

A Linear PTC Thermistor

technical field

The utility model relates to the technical field of thermistors, in particular to a linear PTC thermistor.

Background technique

PTC thermistor is a sensitive component whose resistance value increases linearly with the increase of temperature. It is often used in temperature measurement, temperature control and temperature compensation. The resistance value of the existing PTC thermistor has poor linearity, and at a certain temperature, the resistance value tends to change in steps, and linear compensation measures are required, and the circuit design is relatively complicated; at the same time, the existing PTC thermistor Most of the protective films are rectangular parallelepiped. After long-term use, the protective film of the rectangular parallelepiped is easy to fall off and cannot protect the resistor layer.

Utility model content

The technical problem to be solved by the utility model is the structural and functional problems of the traditional PTC thermistor, providing a linear PTC thermistor with good linearity, good stability, small volume, light weight and long service life .

In order to solve the above technical problems, the technical solution provided by the utility model is: a linear PTC thermistor, including a substrate, a resistor body layer is arranged in the middle of the upper end surface of the substrate, and a protective layer is arranged above the resistor body layer. Surface electrodes are provided on the left and right sides of the resistor body layer, and back electrodes are provided on the left and right sides of the lower end surface of the substrate. The substrate, the surface electrodes and the back electrodes are wrapped with internal electrodes, and the external electrodes of the internal electrodes are A middle electrode is wrapped, and the middle electrode is wrapped with an outer electrode.

Compared with the prior art, the utility model has the advantages that: the linear PTC thermistor has superior stability and reproducibility, the characteristic curve remains unchanged, and the resistance value increases with the increase of temperature, showing a linear change. Good linearity, compared with the thermistor synthesized by PTC polymer ceramics, the linearity is good, no need to take linear compensation measures, which simplifies the circuit design, the temperature coefficient can reach 2000ppm to 3000ppm in general, and the highest temperature coefficient can reach 3500ppm at present, with high sensitivity , High reliability, small size, light weight, standardized appearance, suitable for automatic installation of printed circuit boards.

As an improvement, the protective film is in a trapezoidal shape, and the internal electrodes, intermediate electrodes and external electrodes cover the side surfaces of the protective film.

As an improvement, the internal electrode is made of palladium-silver material.

As an improvement, the intermediate electrode is made of nickel material.

As an improvement, the external electrode is made of tin material.

As an improvement, the substrate is made of aluminum oxide.

Description of drawings

Fig. 1 is a schematic structural view of a linear PTC thermistor of the present invention.

Fig. 2 is a sectional view of a linear PTC thermistor of the present invention.

Fig. 3 is a typical schematic diagram of the resistance value changing with temperature when the temperature coefficients of a linear PTC thermistor of the present invention are 1000, 2000, 3000ppm/°C respectively.

Fig. 4 is a derating curve diagram of a linear PTC thermistor of the present invention.

As shown in the figure: 1. Substrate, 2. Resistor body layer, 3. Protective film, 4. Surface electrode, 5. Back electrode, 6. Internal electrode, 7. Intermediate electrode, 8. External electrode.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in further detail.

When the utility model is actually implemented, it provides a linear PTC thermistor, including a substrate 1, which is characterized in that: a resistor body layer 2 is provided at the middle position of the upper end surface of the substrate 1, and a resistor body layer 2 is arranged above the resistor body layer 2. A protective film 3 is provided, surface electrodes 4 are provided on the left and right sides of the resistor body layer 2, back electrodes 5 are provided on the left and right sides of the lower end surface of the substrate 1, and the substrate 1, the surface electrodes 4 and the back electrodes 5 are The inner electrode 6 is wrapped with the inner electrode 6 , the middle electrode 7 is wrapped with the inner electrode 6 , and the outer electrode 8 is wrapped with the middle electrode 7 .

The protective film 3 is in the shape of a terrace, and the internal electrode 6, the intermediate electrode 7 and the external electrode 8 are covered on the side of the protective film 3, so that the protective film is not easy to fall off, so that it can effectively protect the resistor body layer and prolong the service life.

The internal electrode 6 is made of palladium-silver material, so that it has good oxidation resistance at room temperature, and its oxidation resistance increases with the increase of palladium content in a high-temperature environment.

The intermediate electrode 7 is made of nickel material, so that it has a certain degree of ductility, and has an oxide film on its surface, which can prevent further oxidation reaction and has better oxidation resistance.

The external electrode 8 is made of tin material, so that it does not react with air and water, and at the same time facilitates welding and fixing.

The substrate 1 is made of aluminum oxide material, so that it has good thermal conductivity.

The working principle of the utility model: when the linear PTC thermistor is in use, the external electrode is welded on the circuit board, because the external electrode is made of tin, making the welding of the linear PTC thermistor more convenient and firm , the protective film is in a trapezoidal shape, and the sides of the protective film are covered by external points, intermediate electrodes and internal electrodes, so that the protective film is not easy to fall off, and the resistor body layer is always in a protected state, thereby prolonging the service life of the linear PTC thermistor. When the linear PTC thermistor is used in circuit protection, when the circuit is in a normal state, the current passing through the PTC thermistor for overcurrent protection is less than the rated current, and the PTC thermistor for overcurrent protection is in normal state, and the resistance The value is small and will not affect the normal operation of the protected circuit. When the circuit fails and the current greatly exceeds the rated current, the PTC thermistor for overcurrent protection suddenly heats up and is in a high-impedance state, making the circuit in a relatively "off" state, thereby protecting the circuit from damage. When the fault is eliminated, the PTC thermistor for overcurrent protection will automatically return to a low resistance state, and the circuit will resume normal operation.

The utility model and its implementation have been described above. This description is not restrictive. What is shown in the drawings is only one implementation of the utility model, and the actual structure is not limited thereto. All in all, if a person of ordinary skill in the art is inspired by it, without departing from the purpose of the utility model, without creatively designing a structural method and embodiment similar to the technical solution, it shall be protected by the utility model scope.

Claims (6)

1. a linear PTC thermistor, comprising a substrate (1), is characterized in that: the middle position of the upper end face of the substrate (1) is provided with a resistor body layer (2), and the resistor body layer (2) A protective film (3) is provided above, surface electrodes (4) are provided on the left and right sides of the resistor body layer (2), and back electrodes (5) are provided on the left and right sides of the lower end surface of the substrate (1). The substrate (1), the surface electrode (4) and the back electrode (5) are wrapped with an inner electrode (6), and the inner electrode (6) is wrapped with an intermediate electrode (7), and the outer electrode (7) is Wrapped with external electrodes (8). 2. a kind of linear PTC thermistor according to claim 1, is characterized in that: described protective film (3) is terraced shape, and described internal electrode (6), intermediate electrode (7) and external electrode ( 8) Cover on the side of the protective film (3). 3. A linear PTC thermistor according to claim 1, characterized in that: the internal electrode (6) is made of palladium-silver material. 4. A linear PTC thermistor according to claim 1, characterized in that: the intermediate electrode (7) is made of nickel. 5. A linear PTC thermistor according to claim 1, characterized in that: said external electrode (8) is made of tin material. 6. A linear PTC thermistor according to claim 1, characterized in that: the substrate (1) is made of aluminum oxide.