Pyroelectric infrared sensor with low heat loss

Abstract

The utility model relates to the technical field of pyroelectric infrared sensors, and discloses a pyroelectric infrared sensor with low heat loss, which comprises a main pin, a packaging base arranged at the upper end of the main pin, a circuit board arranged at the upper end of the packaging base and used for reading signals, and a pyroelectric sensitive element arranged at the center of the surface of the upper end of the circuit board. A packaging cap is arranged outside the circuit board and the pyroelectric sensitive element, the pyroelectric sensitive element is composed of an infrared absorption layer, an upper electrode, a detection element, a lower electrode and a heat insulation layer, the heat insulation layer is arranged at the lowermost end of the pyroelectric sensitive element, and small holes are reserved in the surface of the heat insulation layer. According to the pyroelectric infrared sensor with the low heat loss, the heat insulation layer and the conductive small holes are arranged, the heat loss of a detector can be effectively reduced by adding the heat insulation layer, meanwhile, the most basic electrical conduction can be ensured by the reserved small hole structure, the precision of elargol in the sensitive element pasting process is relaxed, and the sensitivity of the sensor is improved. And the process difficulty in the production process is greatly simplified.

Description

Technical Field

[0001] The utility model relates to the technical field of pyroelectric infrared sensors, in particular to a pyroelectric infrared sensor with low heat loss. Background Art

[0002] A pyroelectric infrared sensor is a device that uses the principle that a substance generates heat after absorbing radiation for detection. The core structure includes pyroelectric materials, insulation structures, compensation structures, absorption layers, and readout signals. Certain materials will produce temperature changes after being exposed to infrared radiation, and then generate electrical signals. By measuring the heat changes generated by the material, the infrared radiation in the surrounding environment is detected, thereby realizing the detection and identification of the target. Due to its advantages such as fast response, high detection rate, no need for refrigeration, and ease of use, pyroelectric infrared detectors have been widely used in industry, agriculture, military, environmental monitoring, and medical fields.

[0003] The heat loss of pyroelectric infrared sensors is one of the main limiting factors of pyroelectric detector performance, including the effects caused by heat conduction and heat radiation. In order to suppress this effect, some researchers have proposed a microbridge structure, which reduces the direct contact between the sensitive element and the circuit board, thereby reducing the impact of heat transfer to the circuit board on device performance.

[0004] At present, the construction of this microbridge structure does reduce the heat loss of the sensitive element to a certain extent, but it involves complex MEMS processing technology, which undoubtedly increases the difficulty and cost of detector production. Therefore, it is necessary to provide a pyroelectric infrared sensor with low heat loss to solve the above problems. Utility Model Content

[0005] In view of the deficiencies of the prior art, the utility model provides a pyroelectric infrared sensor with low heat loss, which solves the problems mentioned in the above background.

[0006] The utility model provides the following technical solution: a pyroelectric infrared sensor with low heat loss, comprising a main pin, a packaging base is arranged on the upper end of the main pin, a circuit board for reading signals is arranged on the upper end of the packaging base, a pyroelectric sensitive element is arranged at the center of the upper end surface of the circuit board, and a packaging cap is arranged outside the circuit board and the pyroelectric sensitive element;

[0007] The pyroelectric sensitive element is composed of an infrared absorption layer, an upper electrode, a detection element, a lower electrode and a heat insulation layer. The heat insulation layer is placed at the lower end of the pyroelectric sensitive element. There are reserved small holes on the surface of the heat insulation layer for electrical conduction between the pyroelectric sensitive element and a circuit board for reading signals.

[0008] Preferably, the upper electrode and the lower electrode are respectively plated on two sides of the detection element, and the infrared absorption layer is arranged on a side of the upper electrode facing away from the detection element.

[0009] Preferably, the heat insulating layer is arranged on a side of the lower electrode facing away from the detection element, and the heat insulating layer is provided with small holes for electrical conduction through a mask.

[0010] Preferably, the pyroelectric sensitive element is made of pyroelectric material, and the thermal insulation layer is made of insulating material.

[0011] Preferably, a resistor is disposed on the upper surface of the circuit board and located on one side of the pyroelectric sensitive element, and a field effect transistor is disposed on the side of the pyroelectric sensitive element away from the resistor.

[0012] Preferably, the resistor and the field effect transistor are both welded to pads on a circuit board via pins, and an insulating material layer is provided on the surface of the package base.

[0013] Preferably, a filter is embedded in the center of the upper end of the packaging cap.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] 1. This low heat loss pyroelectric infrared sensor forms a heat-insulating layer with small holes by placing a mask on the lower electrode layer and using magnetron sputtering silicon dioxide. Different from the traditional MEMS microbridge structure, this method is convenient, fast, simple and easy to operate. Adding a heat-insulating layer can effectively reduce the heat loss of the detector. At the same time, the reserved small hole structure can also ensure the most basic electrical conduction, thus ensuring the normal operation of the pyroelectric infrared sensor. This method relaxes the accuracy of silver glue during the pasting process of the sensitive element, greatly simplifying the process difficulty in the production process.

[0016] 2. The low heat loss pyroelectric infrared sensor improves the stability and life of the infrared filter by embedding the filter on the package cap shell, and effectively ensures the insulation between the pad and the package base by providing an insulating material layer on the surface of the package base. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an exploded view of the overall structure of the pyroelectric infrared sensor with low heat loss of the utility model;

[0018] Figure 2 It is a structural schematic diagram of the circuit board of the utility model;

[0019] Figure 3 This is a schematic diagram of the structure of the pyroelectric sensitive element of the utility model;

[0020] Figure 4 It is a structural schematic diagram of the packaging cap of the utility model.

[0021] In the figure: 1. main pin; 2. package base; 3. circuit board; 4. pyroelectric sensitive element; 401. infrared absorption layer; 402. upper electrode; 403. detection element; 404. lower electrode; 405. thermal insulation layer; 5. package cap; 501. filter; 6. resistor; 7. field effect transistor. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] See also Figure 1-4 A pyroelectric infrared sensor with low heat loss comprises a main pin 1, a package base 2 is arranged on the upper end of the main pin 1, a circuit board 3 for reading signals is arranged on the upper end of the package base 2, a pyroelectric sensitive element 4 is arranged at the center of the upper end surface of the circuit board 3, and a package cap 5 is arranged outside the circuit board 3 and the pyroelectric sensitive element 4;

[0024] The pyroelectric sensitive element 4 is composed of an infrared absorption layer 401, an upper electrode 402, a detection element 403, a lower electrode 404 and a heat insulation layer 405. The heat insulation layer 405 is placed at the lower end of the pyroelectric sensitive element 4. There are reserved small holes on the surface of the heat insulation layer 405 for electrical conduction between the pyroelectric sensitive element 4 and the circuit board 3 for reading signals.

[0025] Among them; the upper electrode 402 and the lower electrode 404 are respectively plated on both sides of the detection element 403, the infrared absorption layer 401 is arranged on the side of the upper electrode 402 away from the detection element 403, and the heat insulation layer 405 is arranged on the side of the lower electrode 404 away from the detection element 403. The heat insulation layer 405 is reserved with small holes for electrical conduction through a mask. The pyroelectric sensitive element 4 is made of pyroelectric material, and the heat insulation layer 405 is made of insulating material. A mask is placed on the lower electrode 404 layer, and magnetron sputtering silicon dioxide is used to form a heat insulation layer 405 with small holes. Different from the traditional MEMS microbridge structure, this method is convenient, fast, simple and easy to operate. Adding the heat insulation layer 405 can effectively reduce the heat loss of the detector. At the same time, the reserved small hole structure can also ensure the most basic electrical conduction, thereby ensuring the normal operation of the pyroelectric infrared sensor. In addition, this method relaxes the accuracy of silver glue during the pasting process of the sensitive element, greatly simplifying the process difficulty in the production process.

[0026] Among them, a resistor 6 is arranged on the upper surface of the circuit board 3 and located on one side of the pyroelectric sensitive element 4, and a field effect transistor 7 is arranged on the side of the pyroelectric sensitive element 4 away from the resistor 6. The resistor 6 and the field effect transistor 7 are both welded to the pads on the circuit board 3 through pins, and an insulating material layer is arranged on the surface of the package base 2. Since the three pins of the field effect transistor 7 are sequentially welded to the corresponding pads on the lower surface of the circuit board 3, the insulating material layer is arranged on the surface of the package base 2 to effectively ensure that the pads and the package base 2 are insulated.

[0027] Among them, a filter 501 is embedded in the center of the upper end of the packaging cap 5. By embedding the filter 501 in the housing of the packaging cap 5, the stability and life of the infrared filter 501 are improved.

[0028] Working principle: by placing a mask on the lower electrode 404 layer, a heat-insulating layer 405 with small holes is formed by magnetron sputtering silicon dioxide. Different from the traditional MEMS micro-bridge structure, this method is convenient, fast, simple and easy to operate. Adding the heat-insulating layer 405 can effectively reduce the heat loss of the detector. At the same time, the reserved small hole structure can also ensure the most basic electrical conduction, thereby ensuring the normal operation of the pyroelectric infrared sensor. In addition, this method relaxes the accuracy of the silver glue during the pasting of the sensitive element, which greatly simplifies the process difficulty in the production process.

[0029] Furthermore, by embedding the filter 501 on the housing of the packaging cap 5 , the stability and life of the infrared filter 501 are improved, and by providing an insulating material layer on the surface of the packaging base 2 , the insulation between the pad and the packaging base 2 is effectively ensured.

[0030] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pyroelectric infrared sensor with low heat loss, characterized in that: It comprises a main pin (1), a packaging base (2) is arranged at the upper end of the main pin (1), a circuit board (3) for reading out signals is arranged at the upper end of the packaging base (2), a pyroelectric sensitive element (4) is arranged at the center of the upper end surface of the circuit board (3), and a packaging cap (5) is arranged outside the circuit board (3) and the pyroelectric sensitive element (4); The pyroelectric sensitive element (4) is composed of an infrared absorption layer (401), an upper electrode (402), a detection element (403), a lower electrode (404) and a heat insulation layer (405). The heat insulation layer (405) is placed at the bottom of the pyroelectric sensitive element (4). A small hole is reserved on the surface of the heat insulation layer (405) for electrical conduction between the pyroelectric sensitive element (4) and a circuit board (3) for reading out signals.

2. A pyroelectric infrared sensor with low heat loss according to claim 1, characterized in that: The upper electrode (402) and the lower electrode (404) are respectively plated on two sides of the detection element (403), and the infrared absorption layer (401) is arranged on a side of the upper electrode (402) facing away from the detection element (403).

3. A pyroelectric infrared sensor with low heat loss according to claim 2, characterized in that: The heat insulation layer (405) is arranged on a side of the lower electrode (404) facing away from the detection element (403), and the heat insulation layer (405) is provided with electrically conductive small holes reserved through a mask.

4. The pyroelectric infrared sensor with low heat loss according to claim 1, characterized in that: The pyroelectric sensitive element (4) is made of a pyroelectric material, and the heat insulation layer (405) is made of an insulating material.

5. The pyroelectric infrared sensor with low heat loss according to claim 1, characterized in that: A resistor (6) is provided on the upper surface of the circuit board (3) and located on one side of the pyroelectric sensitive element (4), and a field effect tube (7) is provided on the side of the pyroelectric sensitive element (4) away from the resistor (6).

6. The low heat loss pyroelectric infrared sensor according to claim 5, characterized in that: The resistor (6) and the field effect tube (7) are both welded to pads on the circuit board (3) via pins, and an insulating material layer is provided on the surface of the packaging base (2).

7. The low heat loss pyroelectric infrared sensor according to claim 1, characterized in that: A filter (501) is inlaid at the centre of the upper end of the packaging cap (5).

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