Corrosion-resistant pressure sensor

Abstract

The utility model provides a corrosion-resistant pressure sensor comprising a substrate which is used as a main body bearing platform and is provided with a through hole which is used as a sensing channel between a pressure chip and the outside; the pressure chip serves as a sensing unit, is fixedly connected to the substrate at the position of the through hole, and converts physical quantities into electric signals to be output. The box dam is of a hollow cylindrical structure, covers the pressure chip and comprises a side wall and a top wall which are integrally connected, the bottom of the side wall is fixedly connected with the substrate, a glue injection hole is formed in the top wall, and the side wall and the top wall jointly define a glue injection cavity; and the pouring sealant is poured into the glue injection cavity from the glue injection hole to seal the pressure chip in the glue injection cavity and is used for blocking the permeation of corrosive substances. By improving the structure of the box dam, the exposed area of the medium surface can be reduced, and the thickness of the protective glue right above the pressure chip can be increased, so that the permeation track is changed, and the permeation path of a destroying substance is limited, so that the corrosion resistance of the sensor is improved, and the service life of a device is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of sensors, in particular to a corrosion-resistant pressure sensor. Background Art

[0002] The silicon pressure sensor fabricated by MEMS process has the characteristics of simple structure, high sensitivity, high reliability, etc., and is widely used for pressure monitoring and data acquisition in various environments. According to market applications, some sensors work in highly acidic or alkaline environments for a long time, and will be corroded by acids and alkalis, resulting in the disappearance of the circuit and the failure of functions.

[0003] The typical structural form in the current market is an open form, such as Figure 1 shown, fluorosilicone rubber is used to block the penetration of corrosive substances. However, due to the physical properties of the glue, there will be bonding molecular gaps, and some corrosive substances will penetrate through the glue under the combined action of pressure and temperature, reaching the inside of the components to cause damage and resulting in function failure. In addition, after the glue is cured, a sunken dielectric surface will be formed on the top, which not only increases the exposed area, but also makes the thickness of the protective layer in the area directly above the pressure chip relatively thin, increasing the risk of penetration. Its penetration trajectory is as Figure 2 shown, when the pressure sensor is working, the corrosive substance first acts on the dielectric surface of the potting glue (i.e., fluorosilicone rubber) 8, and at high temperatures, the molecules are more active, and the corrosive substance can easily penetrate through the potting glue 8 directly downward (in the direction of the arrow) to reach the surface of the chip 5, reacting with the metal layer on its surface to cause damage and resulting in function failure. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is: in order to overcome the deficiencies in the prior art, the utility model provides a corrosion-resistant pressure sensor.

[0005] The technical solution adopted by the utility model to solve its technical problem is: a corrosion-resistant pressure sensor, comprising

[0006] a substrate, serving as a main body bearing platform, and the substrate is provided with a through hole;

[0007] the through hole, serving as a sensing channel between the pressure chip and the outside;

[0008] a pressure chip, serving as a sensing unit, fixedly connected to the upper part of the substrate at the position of the through hole, converting physical quantities into electrical signals for output; air or medium cannot penetrate from one side of the through hole to the other side.

[0009] The dam, serving as a support for the protective cover and the glue, is a hollow cylindrical structure that covers the pressure chip. It has a side wall and a top wall integrally connected. The bottom of the side wall is fixedly connected to the substrate, and a glue injection hole is provided on the top wall. The side wall and the top wall jointly enclose a glue injection cavity. On the one hand, the dam can serve as a protective cover for the pressure chip and cover it above the chip. On the other hand, it provides support for the protective glue to prevent the glue from overflowing.

[0010] The potting glue is potted into the glue injection cavity through the glue injection hole, and the pressure chip is sealed in the glue injection cavity to prevent the penetration of corrosive substances, which may cause functional failure.

[0011] Preferably, the substrate is a copper clad laminate, a circuit board, or a metal frame formed by injection molding.

[0012] Furthermore, in order to reduce the exposed area of the dielectric surface and ensure the efficiency of glue injection, the diameter of the glue injection hole ranges from 0.5 to 2 mm, and more preferably, from 1 to 2 mm.

[0013] Preferably, the potting glue uses an elastic fluorosilicone gel.

[0014] Furthermore, the bottom of the side wall of the dam is adhesively fixed to the substrate through an adhesive glue.

[0015] Furthermore, the pressure chip is adhesively fixed to the substrate through a chip glue.

[0016] Furthermore, it also includes a wire, which electrically connects the pressure chip to the metal part on the substrate to complete the functional conduction from the component to the metal part.

[0017] The beneficial effects of the present utility model are as follows: The corrosion-resistant pressure sensor provided by the present utility model can reduce the exposed area of the dielectric surface and increase the thickness of the protective glue directly above the pressure chip by improving the structure of the dam, thereby changing the penetration trajectory and restricting the penetration path of the destructive substances, so as to improve the corrosion resistance of the sensor and extend the service life of the device. Description of the Drawings

[0018] The following further illustrates the present utility model in conjunction with the drawings and embodiments.

[0019] Figure 1 is a schematic structural diagram of a sensor in the prior art.

[0020] Figure 2 is a schematic diagram of the penetration trajectory of the dielectric surface of a sensor in the prior art.

[0021] Figure 3 is a schematic structural diagram of the corrosion-resistant pressure sensor of the present utility model.

[0022] Figure 4It is a schematic diagram of the penetration trajectory of the medium surface of the corrosion-resistant pressure sensor of the present utility model.

[0023] In the figure: 1. Substrate, 2. Through hole, 3. Dam, 3.1 Side wall, 3.2 Top wall, 4. Lead wire, 5. Pressure chip, 6. Chip glue, 7. Bonding glue, 8. Potting glue. Specific embodiments

[0024] Now, the present invention will be further described in detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner. Therefore, they only show the components related to the present invention. Directions and references (such as up, down, left, right, etc.) can only be used to assist in the description of the features in the drawings. Therefore, the following specific embodiments are not adopted in a restrictive sense, and the scope of the claimed subject matter is only defined by the appended claims and their equivalents.

[0025] As Figure 3 shown, a corrosion-resistant pressure sensor of the present utility model includes a substrate 1 as a main body bearing platform, and the substrate 1 is provided with a through hole 2 penetrating therethrough; preferably, the substrate 1 is a copper-clad board, a circuit board or a metal frame formed by injection molding. The through hole 2, as a sensing channel between the pressure chip 5 and the outside world, has holes or no holes according to the application scenario. The pressure chip 5, as a sensing unit, is fixedly connected to the substrate 1 at the position of the through hole 2 and converts a physical quantity into an electrical signal output; air or medium cannot penetrate from one side of the through hole 2 to the other side. Preferably, the pressure chip 5 is bonded and fixed to the substrate 1 by the chip glue 6. The dam 3, as a support for the protective cover and glue, is a hollow cylindrical structure, covering the upper part of the pressure chip 5, and includes an integrally connected side wall 3.1 and a top wall 3.2. The bottom of the side wall 3.1 of the dam 3 is fixedly connected to the substrate 1, and the bottom of the side wall 3.1 of the dam 3 is bonded and fixed to the substrate 1 by the bonding glue 7. A glue injection hole is provided on the top wall 3.2. In order to extend the penetration trajectory, the glue injection hole is opened as far as possible from the pressure chip 5. Preferably, in this embodiment, the glue injection hole is opened at the outer edge position of the top wall 3.2; generally, the area of the top wall of the dam is 10 - 30 mm 2, in order to reduce the exposed area of the medium surface and ensure the glue injection efficiency, the diameter of the glue injection hole ranges from 0.5 to 2 mm, and further preferably, 1 to 2 mm, and the area of the hole accounts for 3% to 30% of the area of the top wall. The side wall 3.1 and the top wall 3.2 together enclose a glue injection cavity; the dam 3 can, on the one hand, serve as a protective cover for the pressure chip 5 and cover it above the chip, and on the other hand, provide support for the protective glue to prevent the glue from overflowing; the potting glue 8 is potted into the glue injection cavity from the glue injection hole to seal the pressure chip 5 in the glue injection cavity, and is used to block the penetration of corrosive substances, resulting in functional failure. Preferably, the potting glue 8 is made of elastic fluorosilicone gel. It also includes a wire 4, and the wire 4 electrically connects the pressure chip 5 to the metal part on the substrate 1 to complete the functional conduction from the component to the metal part.

[0026] Working principle:

[0027] As Figure 4 shown, this design is based on the Wheatstone bridge principle. The pressure chip 5 is made of 4 strain resistors etched on the sensing film by semiconductor process to complete the conversion from physics to electric energy, and the product design and packaging are completed through semiconductor packaging technology.

[0028] When this pressure sensor is working, the corrosive substance only acts on the medium surface at the glue injection hole of the potting glue 8, reducing the exposed area and the penetration area; in the high-temperature state, since the distance between the glue injection hole and the pressure chip 5 is relatively far, that is, the thickness of the glue layer is relatively thick, the penetration path of the corrosive molecules is extended. Therefore, it is very difficult for the corrosive substance to penetrate through the potting glue 8 layer to reach the position of the pressure chip 5, thereby avoiding the damage to the metal layer on the surface of the pressure chip 5, avoiding component failure, improving the corrosion resistance, and extending the service life.

[0029] Inspired by the above ideal embodiments according to the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the scope of the present invention. The technical scope of this utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A corrosion-resistant pressure sensor, characterized in that: Comprising A substrate, serving as a main bearing platform, and having through holes penetrating therethrough; The through holes, serving as sensing channels between the pressure chip and the outside world; A pressure chip, serving as a sensing unit, fixedly connected to the substrate at the position of the through hole, and converting a physical quantity into an electrical signal for output; A dam, serving as a support for the protective cover and the glue, being a hollow cylindrical structure, covering the upper part of the pressure chip, having a side wall and a top wall integrally connected, the bottom of the side wall being fixedly connected to the substrate, and having a glue injection hole formed in the top wall, and the side wall and the top wall jointly enclosing a glue injection cavity; Potting glue, potted into the glue injection cavity from the glue injection hole, sealing the pressure chip in the glue injection cavity, and used to block the penetration of corrosive substances.

2. The corrosion-resistant pressure sensor according to claim 1, wherein: The substrate is a copper clad laminate, a circuit board or a metal frame formed by injection molding.

3. The corrosion-resistant pressure sensor according to claim 1, characterized in that: The diameter range of the glue injection hole is 0.5 - 2 mm.

4. The corrosion-resistant pressure sensor according to claim 1, wherein: The potting glue uses elastic fluorosilicone gel.

5. The corrosion-resistant pressure sensor according to claim 1, wherein: The bottom of the side wall of the dam is adhesively fixed to the substrate through adhesive glue.

6. The corrosion-resistant pressure sensor according to claim 1, wherein: The pressure chip is adhesively fixed to the substrate through chip glue.

7. The corrosion-resistant pressure sensor according to claim 1, characterized in that: Further comprising a wire, the wire electrically connecting the pressure chip to a metal part on the substrate.

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