Method for improving stability of absolute pressure type pressure sensor and absolute pressure type pressure sensor

Abstract

The invention discloses a method for improving the stability of an absolute pressure type pressure sensor and the absolute pressure type pressure sensor, and the method comprises the steps: placing an absolute pressure chip in a square groove of a sintering pedestal, and carrying out the positioning of the absolute pressure chip; dispensing glue on the periphery of the sintering base, and bonding the ceramic insulating cover in the inner cavity of the sintering base; a circuit on the absolute pressure chip is connected with a pin on the sintering base through a gold wire, and the pressing ring, the corrugated diaphragm and the sintering base are welded and fixed; a cavity between the corrugated diaphragm and the sintering base is filled with silicone oil, and the cavity is sealed through steel balls. According to the method, in the process of improving the stability of the absolute pressure type pressure sensor, the square groove is formed in the sintering base, and the absolute pressure chip is placed in the square groove of the sintering base, so that on one hand, the absolute pressure chip can be effectively positioned; the internal stress generated by thermal mismatch caused by material performance mismatch between the adhesive and the sintering base and between the adhesive and the chip is eliminated, and the stability of the absolute pressure chip sensor is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure sensor stability, and in particular relates to a method for improving the stability of an absolute pressure sensor and the absolute pressure sensor. Background Art

[0002] In the process of matching the absolute pressure chip with the sintered base, in order to position the absolute pressure chip, the existing technology usually uses an adhesive to bond the absolute pressure chip to the sintered base, then heats the entire structure to the solidification temperature, and finally cools it to room temperature to complete the matching of the absolute pressure chip and the sintered base. However, in this process, due to the poor matching of the thermal expansion coefficients of the materials between the absolute pressure chip, the adhesive and the sintered base, thermal mismatch is prone to occur, resulting in residual thermal stress, causing deformation of the chip, and thus seriously affecting the reliability and stability of the sensor measurement.

[0003] On the other hand, when using adhesive to bond chips, the thickness of the adhesive layer applied on the sintered base is inconsistent, resulting in uneven bonding quality, which can cause chip breakage or short circuit problems, making the stability of the absolute pressure chip poor. Summary of the invention

[0004] The object of the present invention is to provide a method for improving the stability of an absolute pressure sensor and an absolute pressure sensor, so as to solve the technical defects in the prior art that when the absolute pressure chip is positioned, an adhesive is used to bond the absolute pressure chip to a sintered base, and the thickness of the adhesive layer applied on the sintered base is inconsistent, causing the absolute pressure chip to rupture or short-circuit, resulting in poor stability.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, a method for improving the stability of an absolute pressure sensor is provided, comprising:

[0007] Placing the absolute pressure chip in the square groove of the sintered base to position the absolute pressure chip;

[0008] Dispensing glue around the sintered base to bond the ceramic insulating cover to the inner cavity of the sintered base;

[0009] The circuit on the absolute pressure chip is connected to the pins on the sintered base by using gold wire, and the pressure ring, the corrugated diaphragm and the sintered base are welded and fixed;

[0010] The cavity of the corrugated diaphragm and the sintered base is filled with silicone oil, and the cavity is sealed with steel balls.

[0011] Further, when placing the absolute pressure chip in the square groove of the sintered base, positioning the absolute pressure chip specifically includes:

[0012] The absolute pressure chip is placed in the square groove of the sintering base by an automatic crystal bonding machine, and the absolute pressure chip is positioned by using the square groove.

[0013] Furthermore, the length and width of the square groove are 2 mm.

[0014] Furthermore, glue is dispensed around the sintered base to bond the ceramic insulating cover to the inner cavity of the sintered base, which specifically includes:

[0015] Glue is dispensed around the sintered base to bond the ceramic insulating cover to the inner cavity of the sintered base, so that a square space is formed between the ceramic insulating cover and the sintered base, and the square space is used to limit the movement of the absolute pressure chip.

[0016] Furthermore, a circular hole and an incompletely penetrating groove are provided on the ceramic insulating cover, and the groove is used to prevent the ceramic insulating cover from pressing tightly against the surface of the absolute pressure chip to generate internal stress.

[0017] Furthermore, the depth of the groove is greater than the height of the absolute pressure chip.

[0018] Furthermore, after the circuit on the absolute pressure chip is connected to the pins on the sintered base by using gold wires, the method further includes:

[0019] During gold wire bonding, the curvature of the gold wire is modified to prevent the absolute pressure chip from moving in the square groove and damaging the gold wire, thereby causing sensor failure.

[0020] Furthermore, it also includes:

[0021] After the internal stress is released at high temperature, the resistance of the compensation circuit in the sintered base is adjusted using the resistance compensation principle.

[0022] Furthermore, the welding is laser welding.

[0023] In a second aspect, an absolute pressure sensor is provided, including a sensor body, wherein the sensor body adopts the method described above to improve stability.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. In the process of improving the stability of the absolute pressure pressure sensor, this method opens a square groove on the sintered base and places the absolute pressure chip in the square groove of the sintered base. On the one hand, it can effectively position the absolute pressure chip and eliminate the internal stress caused by the thermal mismatch caused by the mismatch in material properties between the adhesive and the sintered base and the chip; on the other hand, it avoids the contact between the insulating cover and the absolute pressure chip when it is placed, thereby improving the reliability and stability of the absolute pressure chip; at the same time, this method reduces the risk of rupture and short circuit of the absolute pressure chip in the later stage due to unstable bonding process, thereby improving the reliability of the absolute pressure chip sensor.

[0026] 2. Through the precise control of the automatic die bonding machine, the absolute pressure chip can be stably fixed in the square groove of the sintering base to ensure that the insulating cover does not contact the absolute pressure chip.

[0027] 3. Setting the size of the square groove to 2mm can better match the absolute pressure chip of corresponding specifications.

[0028] 4. The ceramic insulating cover is firmly bonded to the inner cavity of the sintered base by dispensing glue, forming a stable square space, providing a fixed boundary for the absolute pressure chip, effectively limiting the movement range of the absolute pressure chip when subjected to external shock or vibration, thereby enhancing the overall reliability of the sensor.

[0029] 5. By opening an incompletely penetrating groove on the ceramic insulating cover, a buffer area can be formed, so that when the ceramic absolute pressure chip is subjected to external pressure or temperature changes, the glass expansion can have a certain deformation space, thereby reducing the direct pressure on the surface of the absolute pressure chip and effectively reducing the generation of internal stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A flow chart of a method for improving the stability of an absolute pressure sensor provided by the present invention;

[0032] Figure 2 A schematic diagram of the cooperation between the ceramic insulating cover and the sintered base in the method for improving the stability of the absolute pressure sensor provided by the present invention;

[0033] Figure 3 A schematic diagram of the structure of a ceramic insulating cover in the method for improving the stability of an absolute pressure sensor provided by the present invention;

[0034] Figure 4 A schematic diagram of the first matching between the ceramic insulating cover and the absolute pressure chip in the method for improving the stability of the absolute pressure sensor provided by the present invention;

[0035] Figure 5 A second schematic diagram of the cooperation between the ceramic insulating cover and the absolute pressure chip in the method for improving the stability of the absolute pressure sensor provided by the present invention;

[0036] Figure 6 A schematic diagram of assembling an absolute pressure sensor in a method for improving the stability of an absolute pressure sensor provided by the present invention;

[0037] Figure 7 It is a schematic diagram of an absolute pressure sensor of the prior art;

[0038] Figure 8 It is a schematic diagram of the structure of a ceramic insulating cover in an absolute pressure sensor of the prior art;

[0039] Among them: 1. Pressure ring; 2. Corrugated diaphragm; 3. Ceramic insulation cover; 4. Absolute pressure chip; 5. Sintered base; 6. Steel ball; 7. Compensation circuit; 8. Traditional absolute pressure pressure sensor; 9. Traditional ceramic insulation cover. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0044] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the process of matching the absolute pressure chip with the sintered base, in order to effectively position the absolute pressure chip, the prior art generally uses an adhesive to connect the absolute pressure chip to the sintered base to achieve the positioning of the absolute pressure chip. Figure 7 and Figure 8 As shown; the conventional absolute pressure sensor 8 is then connected to the conventional ceramic insulating cover 9, and then the whole structure is heated to the solidification temperature, and finally cooled to room temperature to complete the connection between the absolute pressure chip and the sintered base. However, in this process, due to the poor matching of the thermal expansion coefficients of the materials between the absolute pressure chip, the adhesive and the sintered base, thermal mismatch occurs, resulting in residual thermal stress, causing deformation of the chip, which in turn seriously affects the reliability and stability of the sensor measurement.

[0047] On the other hand, when using adhesive to bond chips, the thickness of the adhesive layer applied on the sintered base is inconsistent, resulting in uneven bonding quality, which can cause chip breakage or short circuit problems, making the stability of the absolute pressure chip poor.

[0048] In order to solve the above technical defects, the inventor provides a method for improving the stability of an absolute pressure sensor and an absolute pressure sensor.

[0049] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0050] In a first aspect of an embodiment of the present invention, a method for improving the stability of an absolute pressure sensor is provided. Figure 1 As shown, including:

[0051] S101, placing the absolute pressure chip in the square groove of the sintered base, and positioning the absolute pressure chip; illustratively, the absolute pressure chip 4 is placed in the square groove of the sintered base 5 by an automatic crystal bonding machine, and the absolute pressure chip 4 is positioned by the square groove. Through the precise control of the automatic crystal bonding machine, the absolute pressure chip 4 can be stably fixed in the square groove of the sintered base 5; wherein the size of the square groove is determined according to the size of the absolute pressure chip 4, such as Figure 2 As shown, the length and width of the square groove are 2 mm, which can better match the absolute pressure chip 4 of corresponding specifications. When the absolute pressure chip 4 is installed in the square groove, the square groove can give the absolute pressure chip 4 a 0.1 mm activity margin.

[0052] S102, glue is applied around the sintered base to bond the ceramic insulating cover to the inner cavity of the sintered base; illustratively, after glue is applied around the sintered base 5, the ceramic insulating cover 3 is bonded to the inner cavity of the sintered base 5, so that a square space is formed between the ceramic insulating cover 3 and the sintered base 5, providing a fixed boundary for the absolute pressure chip 4, effectively limiting the movement range of the absolute pressure chip 4 when subjected to external shock or vibration, thereby enhancing reliability. Then, as Figure 3 and Figure 4 As shown, a circular hole and an incompletely penetrating groove are provided on the ceramic insulating cover 3 , and the groove is used to prevent the ceramic insulating cover 3 from pressing the surface of the absolute pressure chip 4 tightly to generate internal stress. The depth of the groove is greater than the height of the absolute pressure chip 4 .

[0053] S103, use gold wire to connect the circuit on the absolute pressure chip with the pin on the sintered base, and weld the pressure ring, corrugated diaphragm and sintered base together; illustratively, use gold wire to connect the circuit on the absolute pressure chip 4 with the pin on the sintered base 5, and transmit the pressure signal felt by the absolute pressure chip 4 to the outside through the gold wire and the pin for measurement; it is worth noting that when the gold wire is bonded, the arc of the gold wire is modified to prevent the absolute pressure chip 4 from moving in the square groove and damaging the gold wire, causing sensor failure. Finally, laser welding technology is used to weld and fix the pressure ring 1, corrugated diaphragm 2 and sintered base 5 together to ensure the sealing of the cavity and prevent the absolute pressure chip 4 from being contaminated when measuring the medium, which affects the reliability of the product.

[0054] S104, filling the cavity of the corrugated diaphragm and the sintered base with silicone oil, and sealing the cavity with steel balls; illustratively, Figure 5 and Figure 6As shown, after the cavity between the corrugated diaphragm 2 and the sintered base 5 is completely filled with silicone oil, it is sealed with a steel ball 6. Then, after the internal stress is released at high temperature, the resistance compensation principle is used to adjust the resistance of the compensation circuit 7 in the sintered base 5, so as to improve the stability of the absolute pressure sensor.

[0055] In the process of improving the stability of the absolute pressure type pressure sensor, the method ensures the accuracy and stability of the position of the absolute pressure chip 4 by placing the absolute pressure chip 4 in the square groove of the sintered base 5 and positioning it. On the one hand, the absolute pressure chip can be effectively positioned, eliminating the internal stress caused by the thermal mismatch caused by the mismatch between the material properties of the adhesive, the sintered base and the chip; on the other hand, it avoids the contact between the insulating cover and the absolute pressure chip when it is placed, thereby improving the reliability and stability of the absolute pressure chip; at the same time, this method reduces the risk of the absolute pressure chip breaking and short circuiting in the later stage due to the unstable bonding process, thereby improving the reliability of the absolute pressure chip sensor.

[0056] At the same time, this method reduces the risk of the absolute pressure chip 4 being cracked and short-circuited in the later stage due to the unstable bonding process, thereby improving the reliability of the absolute pressure chip 4 sensor.

[0057] According to a second aspect of an embodiment of the present invention, an absolute pressure sensor is provided, including a sensor body, wherein the sensor body adopts the above method to improve stability.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A method for improving the stability of an absolute pressure sensor, characterized in that: include: Placing the absolute pressure chip in the square groove of the sintered base to position the absolute pressure chip; Dispensing glue around the sintered base to bond the ceramic insulating cover to the inner cavity of the sintered base; The circuit on the absolute pressure chip is connected to the pins on the sintered base by using gold wire, and the pressure ring, the corrugated diaphragm and the sintered base are welded and fixed; The cavity of the corrugated diaphragm and the sintered base is filled with silicone oil, and the cavity is sealed with steel balls.

2. The method according to claim 1, characterized in that When placing the absolute pressure chip in the square groove of the sintered base, positioning the absolute pressure chip specifically includes: The absolute pressure chip is placed in the square groove of the sintering base by an automatic crystal bonding machine, and the absolute pressure chip is positioned by using the square groove.

3. The method according to claim 1 or 2, characterized in that: The length and width of the square groove are 2 mm.

4. The method according to claim 1, characterized in that: Gluing is applied around the sintered base to bond the ceramic insulating cover to the inner cavity of the sintered base, specifically comprising: Glue is dispensed around the sintered base to bond the ceramic insulating cover to the inner cavity of the sintered base, so that a square space is formed between the ceramic insulating cover and the sintered base, and the square space is used to limit the movement of the absolute pressure chip.

5. The method according to claim 4, characterized in that The ceramic insulating cover is provided with a round hole and an incompletely penetrating groove, and the groove is used to prevent the ceramic insulating cover from pressing tightly against the surface of the absolute pressure chip to generate internal stress.

6. The method according to claim 5, characterized in that The depth of the groove is greater than the height of the absolute pressure chip.

7. The method according to claim 1, characterized in that After connecting the circuit on the absolute pressure chip with the pins on the sintered base using gold wire, it also includes: During gold wire bonding, the curvature of the gold wire is modified to prevent the absolute pressure chip from moving in the square groove and damaging the gold wire, thereby causing sensor failure.

8. The method according to claim 1, characterized in that Also includes: After the internal stress is released at high temperature, the resistance of the compensation circuit in the sintered base is adjusted using the resistance compensation principle.

9. The method according to claim 1, characterized in that: The welding is laser welding.

10. An absolute pressure sensor, comprising a sensor body, characterized in that: The sensor body adopts the method described in any one of claims 1-9 to improve stability.

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