阅读说明：本技术 一种dfn封装的数字式红外温度传感器 (Digital infrared temperature sensor of DFN encapsulation ) 是由 杨明鹏 鹿永琪 冯李航 姚敏 于 2020-06-24 设计创作，主要内容包括：本发明公开一种DFN封装的数字式红外温度传感器,包括顶部带有开窗的DFN封装外壳,DFN封装外壳内设有热电堆、TC模板和ASIC模块,DFN封装外壳开窗处设有红外滤光片,所述红外滤光片与DFN封装外壳围成密闭空间；DFN封装外壳上设有引气孔和排气孔,DFN封装外壳底部设有引脚,DFN封装外壳内壁上设有金属屏蔽层和SiO<Sub>2</Sub>薄膜。具有微型化,低成本,电磁屏蔽效能好,测量精度高,易读性好,成型工艺简单,适合大规模的生产,应用广泛的优点。(The invention discloses a DFN packaged digital infrared temperature sensor, which comprises a DFN packaging shell with a window at the top, wherein a thermopile, a TC template and an ASIC module are arranged in the DFN packaging shell; the DFN packaging shell is provided with air guiding holes and air exhaust holes, and the bottom of the DFN packaging shellThe inner wall of the DFN packaging shell is provided with a metal shielding layer and SiO 2 A film. The device has the advantages of miniaturization, low cost, good electromagnetic shielding efficiency, high measurement precision, good readability, simple forming process, suitability for large-scale production and wide application.)

1. A DFN packaged digital infrared temperature sensor is characterized in that: the infrared light source module comprises a DFN packaging shell (1) with a window at the top, wherein a thermopile (7), a TC template (5) and an ASIC (application specific integrated circuit) module (8) are arranged in the DFN packaging shell (1), an infrared filter (2) is arranged at the window of the DFN packaging shell, and a closed space is enclosed by the infrared filter (2) and the DFN packaging shell (1); the DFN packaging shell is provided with an air guiding hole (3) and an air exhaust hole (4), the bottom of the DFN packaging shell is provided with a pin, and the inner wall of the DFN packaging shell is provided with a metal shielding layer and SiO₂A film thermal insulation layer.

2. The DFN packaged digital infrared temperature sensor of claim 1, wherein: the metal shielding layer is formed by sequentially evaporating a Cu metal layer and a Ni metal layer on the inner wall of a DFN-packaged shell, wherein the thickness of the copper coating is 0.5-3.8 mu m, and the thickness of the nickel coating is 0.2-0.5 mu m.

3. The DFN packaged digital infrared temperature sensor according to claim 1 or 2, wherein: SiO 2₂The film thickness is 500 nm or 1 μm.

4. The DFN packaged digital infrared temperature sensor of claim 3, wherein: the thermopile (7) is a micro thermopile, and can realize conversion from infrared radiation energy to voltage signals.

5. The DFN packaged digital infrared temperature sensor of claim 4, wherein: the wavelength pass band of the infrared filter (2) is 2-14 mu m, and the corresponding temperature measurement range is about-65-200 ℃.

6. The DFN packaged digital infrared temperature sensor of claim 5, wherein: the TC module (5) adopts a metal thermal resistor, a PTC thermistor or an NTC thermistor.

7. The DFN packaged digital infrared temperature sensor of claim 6, wherein: the TC module (5) adopts a miniature metal thermal resistor, the size of the miniature metal thermal resistor is 0.2 mm-0.3 mm, and the metal material of the miniature metal thermal resistor is platinum.

8. The DFN packaged digital infrared temperature sensor of claim 6, wherein: the width of the Pt thermistor wire is 2 mu m, the distance is 8 mu m, and the detection precision is +/-0.05 ℃.

9. The DFN packaged digital infrared temperature sensor of claim 8, wherein: an enclosed space enclosed by the infrared filter (2) and the DFN packaging shell (1) is filled with inert gas, and the inert gas is argon.

10. The DFN packaged digital infrared temperature sensor of claim 9, wherein: five pins are installed to the outside bottom of packaging shell, and the pin is SDA, VDD, GND, SCL, ADDR respectively.

Technical Field

The invention belongs to the technical field of infrared temperature sensors, and particularly relates to a digital infrared temperature sensor packaged by a DFN (distributed feedback network).

Background

After a sensitive unit of the infrared temperature sensor absorbs infrared radiation of a target to be measured, an infrared absorption area of the infrared temperature sensor generates temperature rise, so that changes of certain physical quantities of the temperature sensor, such as changes of thermal voltage or thermal resistance, are caused. One advantage of the infrared temperature sensor is that non-contact measurement can be realized, and contact temperature measurement can be avoided in the situation that the infrared temperature sensor is not suitable for being in contact with a target to be measured, for example, the non-contact temperature measurement plays an important role in epidemic prevention work of infectious diseases. In addition, the infrared temperature sensor also has the advantages of high response speed, safe use, long service life and the like.

At present, a thermopile is more selected as a temperature sensing element of an infrared temperature sensor and is generally formed by connecting a plurality of thermocouples in series, the temperature of the hot end of the thermopile is increased by infrared radiation of a target to be detected, and due to the Seebeck effect, thermoelectromotive force can be generated at the hot end and the cold end of the thermopile. And compensating the cold end temperature of the thermoelectromotive force to obtain the real-time temperature of the target to be measured.

Common infrared temperature sensor's packaging mode on the market at present is the TO can encapsulation, encapsulates the infrared thermopile of high accuracy in the metal TO can, but the TO encapsulation volume is great, is difficult for integrating.

The DFN plastic packaging method is mainly used in the packaging process of the traditional IC integrated circuit at present, and has the advantages of small volume, batch production and the like; however, DFN plastic encapsulation methods are currently less used in thermopile infrared temperature sensors. The following technical difficulties mainly exist: (1) the thermopile receives less infrared radiation energy, and has high heat insulation requirement on heat; (2) DFN plastic packaging, electromagnetic shielding efficiency is weak. In addition, although some domestic companies have successfully developed micro-packaged infrared thermopile sensors, the output signals are still analog voltage signals, which is not favorable for popularization and application of the product.

Disclosure of Invention

In view of the problems with the prior art described above, the present invention provides a digital infrared temperature sensor packaged with a DFN.

In order to achieve the purpose of the invention, the specific technical scheme of the invention is as follows:

a DFN packaged digital infrared temperature sensor comprises a DFN packaging shell with a window at the top, wherein a thermopile, a TC template and an ASIC module are arranged in the DFN packaging shell, an infrared filter is arranged at the window of the DFN packaging shell, and a closed space is enclosed by the infrared filter and the DFN packaging shell; the DFN packaging shell is provided with an air guiding hole and an air exhaust hole, the bottom of the DFN packaging shell is provided with a pin, and the inner wall of the DFN packaging shell is provided with a metal shielding layer and SiO₂A film thermal insulation layer.

Furthermore, the metal shielding layer is formed by evaporating a copper coating and a copper coating on the inner wall of the DFN-packaged shell, wherein the thickness of the copper coating is 0.5-3.8 μm, and the thickness of the nickel coating is 0.2-0.5 μm.

Further, the SiO₂The film thickness is 500 nm or 1 μm.

Furthermore, the thermopile is a micro thermopile, and conversion of infrared radiation energy to a voltage signal can be realized.

Further, the wavelength pass band of the infrared filter is 2-14 μm, and the corresponding temperature measurement range is about-65-200 ℃.

Further, the TC module adopts a metal thermal resistor, a PTC thermistor or an NTC thermistor.

Furthermore, the TC module adopts a miniature metal thermal resistor, the size of the miniature metal thermal resistor is 0.2 mm-0.3 mm, and the metal material of the miniature metal thermal resistor is platinum.

Furthermore, the width of the Pt thermistor wire is 2 μm, the distance is 8 μm, and the detection precision is +/-0.05 ℃.

Furthermore, an enclosed space enclosed by the infrared filter and the DFN packaging shell is filled with inert gas, and the inert gas is argon.

Furthermore, five pins, namely SDA, VDD, GND, SCL, ADDR, are installed at the bottom end outside the package.

The digital infrared temperature sensor packaged by the DFN has the following beneficial effects:

(1) the digital infrared temperature sensor packaged by the DFN is based on the MEMS technology, is internally provided with the miniature thermopile, adopts a plastic DFN packaging mode, realizes the miniaturization of the infrared temperature sensor, and has the advantages of miniaturization, low cost, simple molding process, suitability for large-scale production and wide application on the premise of equivalent reliability to metal or ceramic materials.

(2) According to the invention, the inert gas is filled in the DFN shell through the two air holes, so that the thermal resistance in the shell is increased, the heat loss rate of the hot end of the thermopile is reduced, and the detection precision is improved.

(3) According to the invention, the metal shielding layer is evaporated on the inner wall of the DFN, so that the electromagnetic shielding efficiency of the infrared temperature sensor is improved; the Cu/Ni double plating layer adopted by the invention has good electromagnetic shielding function, and the nickel plating layer has better wear resistance and corrosion resistance, can protect the internal copper layer from being oxidized, and is durable for a long time.

(4) The invention continues to evaporate a layer of SiO outside the DFN metal shielding layer₂The film plays a role of preventing short circuit of the connecting line and simultaneously is SiO₂The thermal resistance is higher, the heat loss rate is further reduced, and the detection precision is improved;

(5) the coating process adopted by the invention can be used for mass production. Compared with the common film pasting process, the production automation can be realized, and film pasting errors, such as electromagnetic leakage and the like caused by incomplete film pasting in the film pasting process, can be avoided;

(6) the ASIC module is simultaneously packaged in the shell, signal processing and temperature compensation of the thermopile and the TC module are realized, a voltage input port and a digital output port are provided, and the readability and the easy integration of the temperature sensor are improved.

Drawings

FIG. 1 is a schematic diagram of the overall structure of the present invention (also referred to as abstract figure);

FIG. 2 is a top view of the present invention;

FIG. 3 is a shell view of the present invention;

FIG. 4 is a Pt thermal resistor of the present invention;

in the figure: 1. a DFN package housing; 2. an infrared filter; 3. an air vent; 4. an exhaust hole; 5. a TC module; 6. assembling welding spots; 7. a thermopile; 8. an ASIC module; 201. a window; 202. SDA; 203. VDD; 204. GND; 205. an SCL; 206. ADDR; 301. a DFN package housing; 302. SiO 2₂A film; 303. Cu/Ni plating layer.

Detailed Description

In order to better understand the method and system of the present invention for those skilled in the art, the present invention is further described below with reference to the accompanying drawings.