Self-positioning leadless packaging high-temperature pressure sensor and manufacturing method thereof

Abstract

The invention discloses a self-positioning leadless packaging high-temperature pressure sensor and a manufacturing method thereof, and belongs to the pressure sensor technology. The leadless packaging high-temperature pressure sensor comprises a cap, a base, a chip body, bonding slurry, a lead and a tube shell, the cap and the tube shell are in butt joint to form a cavity, the base and the chip body are both arranged in the cavity, and the chip body is located on one side of the base. The inner wall of the tube shell, the base and the chip main body jointly define an annular groove, the bonding slurry is arranged in the annular groove, and the lead respectively penetrates through the tube shell and the base and is connected with the chip main body. According to the leadless packaging high-temperature pressure sensor, the bonding strength of the chip main body can be improved, the stability of the pressure sensor is ensured, and the problem of air tightness between the base and the tube shell can be avoided.

Description

Technical Field

[0001] This invention relates to the field of pressure sensor technology, specifically to a self-positioning, leadless packaged high-temperature pressure sensor and its manufacturing method. Background Technology

[0002] Pressure sensors, as one of the most widely used sensors, have become indispensable key equipment in modern industrial applications. High-temperature pressure sensors, in particular, are widely used in aerospace, blasting, and process industries. Accurate pressure monitoring under these extreme conditions is crucial; for example, monitoring the operation of aircraft and spacecraft can improve engine combustion performance and propulsion efficiency, thereby reducing failure rates and maintenance costs. Typically, when high-temperature pressure sensors are applied to these harsh environments, they not only need to withstand high temperatures (above 300°C) but also the effects of high-frequency vibration and shock radiation. Therefore, researching and developing pressure sensors that can operate normally in harsh environments such as high temperatures is a current development trend and a key focus.

[0003] Currently, most common pressure sensor packaging solutions are oil-filled packages with leads. This type of packaging, due to the exposed pressure-sensitive chip and leads, suffers from poor corrosion resistance and stability, making it unsuitable for measuring high-dynamic pressure signals. To address the issue of lead-bonded joint failure caused by oil-filled packaging at high temperatures, leadless packaging technology has been proposed and has achieved significant development. Compared to traditional packaging methods, leadless packaging technology utilizes conductive pins and conductive paste sintering to achieve electrical connection between the chip and external electrical signals. It eliminates the lead bonding between the pressure-sensitive chip and the conductive pins, avoiding problems such as oxidation and increased resistance of metal leads under high-temperature conditions, thus ensuring the long-term reliability and stability of high-temperature pressure sensors operating in harsh environments.

[0004] However, existing leadless packaged high-temperature pressure sensors suffer from complex manufacturing processes and poor sealing. Summary of the Invention

[0005] The purpose of this invention is to provide a self-positioning leadless packaged high-temperature pressure sensor to solve the problems of complex manufacturing process and poor sealing performance of leadless packaged structures in the prior art.

[0006] One objective of this invention is to provide a self-positioning, leadless packaged high-temperature pressure sensor, comprising a cap, a base, a chip body, an adhesive paste, leads, and a housing. The cap and the housing are joined to form a cavity. The base and the chip body are both disposed within the cavity, with the chip body located on one side of the base. The inner wall of the housing, the base, and the chip body together define an annular groove. The adhesive paste is disposed within the annular groove. The leads pass through the housing and the base, respectively, and are connected to the chip body.

[0007] Optionally, the base has a positioning portion recessed into the base on the side facing the cap, and the chip body is disposed on the positioning portion.

[0008] Optionally, the shape of the positioning part is adapted to the outer shape of the chip body, and the positioning part is a positioning groove, the cross-sectional shape of the positioning groove and the cross-sectional shape of the chip body are both rectangular.

[0009] Optionally, the thickness of the adhesive slurry ranges from 0.1 mm to 0.3 mm.

[0010] Optionally, the adhesive paste has a through hole extending along the thickness direction of the chip body, and the adhesive paste is fitted onto the outer side wall of the chip body so that the chip body protrudes through the through hole in a direction away from the base.

[0011] Optionally, the coefficients of thermal expansion of the cap, the housing, the base, the adhesive paste, and the chip body are matched.

[0012] Optionally, the number of leads is multiple leads, and the base has through holes extending along the thickness direction of the base. Each through hole corresponds to one of the leads. The chip body has connection holes on the side facing the base that correspond to each of the leads. The leads pass through the through holes and extend into the connection holes, which are filled with conductive paste.

[0013] Optionally, the inner wall of the shell is provided with a stepped portion, and the base is disposed on the stepped portion.

[0014] Another object of the present invention is to provide a method for manufacturing a self-positioning, leadless packaged high-temperature pressure sensor, the method comprising: Provides cap, chip body, base, leads and casing; The lead wire is passed through the base and assembled into the tube shell, and the tube shell, base and lead wire are sintered into one piece; Connect the chip body to the base and connect it to the leads; The adhesive slurry is applied into the annular groove defined by the shell, the base and the chip body and surrounds the chip body, and the adhesive slurry is sintered and formed. Secure the cap and the casing together.

[0015] Optionally, the step of positioning the chip body onto the base and connecting it to the leads includes: A positioning groove is formed on the side of the base facing the cap, and the chip body is housed in the positioning groove.

[0016] Compared with related technologies, the leadless packaged high-temperature pressure sensor of this invention no longer prints the adhesive paste onto the back of the chip body using a screen printing process. This avoids the problems of difficult positioning and high cost associated with screen printing. By coating the adhesive paste around the chip body and ensuring that the adhesive paste simultaneously contacts the inner wall of the housing, the base, and the chip body, the chip body can be bonded to the housing and the base, enhancing the bonding strength of the chip body. Furthermore, since the annular groove is filled with adhesive paste, in addition to the adhesive force, the chip body is also subjected to the combined action of the housing and the adhesive paste, making it less likely to detach from the annular groove. Moreover, the adhesive paste applied to the annular groove can also fill the gap between the base and the housing, thereby improving the airtightness and reliability of the leadless packaged high-temperature pressure sensor. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the leadless packaged high-temperature pressure sensor provided in an embodiment of the present invention; Figure 2 This is an exploded view of the leadless packaged high-temperature pressure sensor provided in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the leadless packaged high-temperature pressure sensor provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the chip body of the leadless packaged high-temperature pressure sensor provided in an embodiment of the present invention; Figure 5 This is a cross-sectional view of the chip body provided in an embodiment of the present invention.

[0018] Reference numerals: 1-Cap; 2-Chip body; 3-Base; 4-Adhesive paste; 5-Lead; 6-Shell; 7-Silicon substrate; 8-Glass; 9-Conductive paste; 300-Positioning groove. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The inventors discovered in their research that traditional leadless packaging structures typically require screen printing to uniformly coat the back of the pressure-sensitive chip with adhesive paste. Since the back of the pressure-sensitive chip also has multiple lead holes for wires to pass through, the adhesive paste must be avoided during screen printing to prevent it from entering and clogging the lead holes. Furthermore, the screen area used for screen printing is much larger than the area of ​​the pressure-sensitive chip, making it difficult for the screen to accurately position the chip. In addition, the screen printing process requires adjusting the screen mesh count and paste thickness, and the paste flow during the later stages of printing can easily clog the lead holes, affecting the conductivity of the pressure-sensitive chip. In practice, to simplify the process, it is often necessary to fill the conductive paste and print the adhesive paste simultaneously. If the adhesive paste is coated on the back of the pressure sensor chip first, the conductive paste in the lead hole must be sintered with the lead first. However, after the lead is sintered, the back of the pressure sensor chip will have multiple leads, which will also provide a complete plane for screen printing. Therefore, the traditional leadless packaging structure has problems such as complex process, troublesome operation and difficult positioning.

[0021] like Figure 1 and Figure 2 As shown, the present invention provides a self-positioning leadless packaged high-temperature pressure sensor, which includes a cap 1, a base 3, a chip body 2, an adhesive paste 4, leads 5, and a housing 6.

[0022] The cap 1 can be made of alloy material, and the shell 6 can also be made of alloy material. The cap 1 and the shell 6 are joined together to form a cavity. By using alloy materials for the cap 1 and the shell 6, the cap 1 and the shell 6 can be fixed together by welding to improve the connection strength between the cap 1 and the shell 6. Specifically, the cap 1 and the shell 6 can be welded together by laser welding.

[0023] The cap 1 and the shell 6 can have any suitable shape. For example, the cap 1 and the shell 6 can be cylindrical or prismatic. Both the cap 1 and the shell 6 are hollow, so a cavity can be formed when they are joined together. The shape of the cavity can be adapted to the shape of the cap 1 and the shell 6. That is, when the cap 1 and the shell 6 are cylindrical, the cavity can also be cylindrical. The cap 1 has multiple pressure-introducing holes on the side away from the shell 5 to ensure pressure introduction and to protect the chip body 2.

[0024] Both the base 3 and the chip body 2 are disposed in the cavity. The chip body 2 is an SOI chip. The base 3 is connected to the shell 6. The chip body 2 is located on one side of the base 3. The base 3 is used to support the chip body 2.

[0025] The relative height of the base 3 is lower than the relative height of the shell 6. Thus, the inner wall of the shell 6, the base 3, and the chip body 2 together define an annular groove. Specifically, the annular groove has a bottom surface, an inner side surface, and an outer side surface. The outer circle of the bottom surface is circular, and the inner circle of the bottom surface is rectangular. The inner side surface of the annular groove surrounds the inner circle of the bottom surface, and the outer side surface of the annular groove surrounds the outer circle of the bottom surface. The bottom surface of the annular groove is part of the top surface of the base 3, the inner side surface of the annular groove is the outer side surface of the chip body 2, and the outer side surface of the annular groove is the inner wall of the shell 6. Thus, the annular groove can be formed by the inner wall of the shell 6, the base 3, and the chip body 2. It can be seen that the sides and bottom surface of the annular groove are closed, and the top surface of the annular groove is open.

[0026] The adhesive paste 4 is filled into the annular groove through the opening, and the leads 5 are respectively passed through the tube shell 6 and the base 3 and connected to the chip body 2.

[0027] Compared to existing technologies, the leadless packaged high-temperature pressure sensor of this invention no longer prints the adhesive paste 4 onto the back of the chip body 2 using a screen printing process. This avoids the problems of difficult positioning, complex operation, and high cost associated with screen printing. By coating the adhesive paste 4 around the chip body 2 and simultaneously contacting the inner wall of the housing 6, the base 3, and the chip body 2, the chip body 2 can be bonded to the housing 6 and the base 3. Compared to coating the adhesive paste 4 onto the bottom surface of the chip body 2, this increases the contact area between the chip body 2 and the adhesive paste 4, thereby enhancing the bonding strength of the chip body 2. Furthermore, since the annular groove is filled with adhesive paste 4, in addition to the adhesive force, the chip body 2 is also subjected to the combined action of the housing 6 and the adhesive paste 4. This ensures that the chip body 2 is not easily detached from the annular groove due to the lateral extrusion force of the housing 6 and the adhesive paste 4, thus enhancing the stability of the chip body 2. Furthermore, when using the leadless packaged high-temperature pressure sensor, it is necessary to keep the top of the chip body 2 and the bottom of the base 3 sealed; otherwise, pressure leakage will occur. By applying the adhesive paste 4 into the annular groove, compared to applying the adhesive paste 4 to the back of the chip body 2 (i.e., the side close to the base 3), the adhesive paste 4 can also fill the gaps between the base 3 and the housing 6, and between the base 3 and the chip body 2, thereby improving the airtightness and reliability of the leadless packaged high-temperature pressure sensor.

[0028] In this invention, the base 3 has a positioning part recessed into the base 3 on the side facing the cap 1. That is, the positioning part is formed by the base 3 itself being recessed into the base. A part of the chip body 2 is disposed in the positioning part. By setting the positioning part on the base 3, the chip body 2 and the base 3 can be accurately positioned, thereby improving the accurate alignment between the lead wire 5 and the chip body 2, which is beneficial to improving the manufacturing efficiency of the leadless packaged high temperature pressure sensor.

[0029] like Figure 2 As shown, the shape of the positioning part is adapted to the outer shape of the chip body 2. The positioning part is a positioning groove 300. The cross-sectional shape of the positioning groove 300 and the cross-sectional shape of the chip body 2 are both rectangular. By setting the shape of the positioning part and the chip body 2 to be the same, a part of the chip body 2 can be just accommodated in the positioning groove 300, preventing the chip body 2 from moving relative to the base 3, thereby achieving accurate alignment between the lead 5 and the chip body 2. The depth of the positioning groove 300 should be less than the thickness of the chip body 2 so that a part of the chip body 2 protrudes from the positioning groove 300, facilitating the bonding paste 4 to bond with a part of the chip body 2.

[0030] like Figure 3As shown, the thickness of the adhesive paste 4 can be in the range of 0.1mm-0.3mm. If the thickness of the adhesive paste 4 is too large, it will affect the output performance of the pressure sensor, and the sintering curve will be difficult to control. The adhesive paste 4 will also be difficult to sinter and mature, and the glassization of the adhesive paste 4 will not be achieved, which will affect the bonding performance of the adhesive paste 4. At the same time, if the thickness of the adhesive paste 4 is too small, the bonding strength will be reduced due to the small contact area with the chip body 2.

[0031] The adhesive paste 4 has through holes extending along the thickness direction of the chip body 2. The through holes are adapted to the shape of the chip body 2. For example, when the cross-sectional shape of the chip body 2 is rectangular, the cross-sectional shape of the through holes is also rectangular. The adhesive paste 4 is fitted onto the outer wall of the chip body 2 so that the chip body 2 protrudes through the through holes in a direction away from the base 3. By setting the through holes, the adhesive paste 4 can bond the chip body 2 from all four sides. That is, the four sides of the chip body 2 can be bonded to the adhesive paste 4 at the same time, which increases the contact area between the chip body 2 and the adhesive paste 4, thereby improving the bonding strength between the chip body 2 and the adhesive paste 4.

[0032] like Figure 4 and Figure 5 As shown, the thermal expansion coefficients of the cap 1, housing 6, base 3, adhesive paste 4, and chip body 2 are matched. Specifically, the cap 1 and housing 6 can be made of 4J34 ceramic sealing alloy, the base 3 can be made of aluminum nitride (AlN) material, the lead wire 5 can be made of 4J29 Kovar alloy, and the chip body 2 includes a silicon substrate 7 and a glass 8. The silicon substrate 7 and the glass 8 are connected to each other. Since the thermal expansion coefficients of the cap 1, housing 6, base 3, lead wire 5, and adhesive paste 4 are approximately the same or similar to those of the silicon substrate 7, thermal stress caused by the mismatch of thermal expansion coefficients at high temperatures can be avoided, thereby preventing damage to the pressure sensor and improving the durability and reliability of the pressure sensor under extreme conditions.

[0033] like Figure 2 As shown, there are multiple leads 5. The base 3 has through holes extending along its thickness direction, with each through hole corresponding to one of the leads 5. For example, Figure 2 The diagram shows five leads 5, therefore five vias are also present, allowing one lead 5 to pass through each via. The chip body 2, facing the base 3, has connection holes corresponding to each lead 5. These connection holes can be tapered. The lead 5 passes through the via and extends into the connection hole, which is filled with conductive paste 9. The conductive paste 9 is used to fix the lead 5 within the connection hole through a sintering process. The coefficient of thermal expansion of the conductive paste 9 matches that of the silicon substrate 7 to avoid thermal stress caused by mismatched coefficients of thermal expansion at high temperatures.

[0034] In this invention, the silicon substrate 7 and glass 8 are sealed using an anodic bonding process. A varistor on one side of the silicon substrate 7 is ion-implanted to form four resistors of equal resistance, thus constituting a Wheatstone bridge. Metal electrodes are sputtered onto the bottom surface of the silicon substrate 7, corresponding to tapered holes. A vacuum-sealed cavity is provided on the side of the glass 8 facing the silicon substrate 7 to accommodate the strain generated during the pressure application of the chip body 2. Conductive paste 9 is filled into the connection holes of the glass 8, enabling electrical signal connection between the lead 5 and the metal electrodes. This leadless packaged high-temperature pressure sensor eliminates the gold wire connection between the pads and gold-plated terminals of the chip body 2. Instead, the lead 5 is electrically connected to the metal electrodes via conductive paste 9. This avoids oxidation and increased resistance of the lead 5 under high-temperature conditions, thus ensuring the reliability and stability of the high-temperature pressure sensor operating in harsh environments.

[0035] In this invention, the inner wall of the shell 6 is provided with a stepped portion, which is an annular structure. The vertical cross-sectional shape of the stepped portion can be L-shaped. The base 3 is disposed on the stepped portion, so that the shell 6 can be supported on the base 3 and at the same time, it can fix the base 3.

[0036] The present invention also provides a method for manufacturing a self-positioning leadless packaged high-temperature pressure sensor, the method comprising: Step S1: Provide cap 1, chip body 2, base 3, lead wire 5 and casing 6; Among them, the number of lead wires 5 is multiple.

[0037] Step S2: Pass the lead wire 5 through the base 3 and assemble it into the tube shell 6, and sinter the tube shell 6, base 3 and lead wire 5 into one piece.

[0038] The base 3 is provided with through holes corresponding to the leads 5, and multiple leads 5 can pass through the through holes one by one, and then the shell 6, the base 3 and the leads 5 are sintered.

[0039] Step S3: Connect the chip body 2 to the base 3 and connect it to the lead wire 5.

[0040] The chip body 2 is connected to the base 3. The chip body 2 has connection holes on the side facing the base 3 that correspond one-to-one with the leads 5. The connection holes are filled with conductive paste 9. The leads 5 passing through the holes can be inserted into the conductive paste 9 in the connection holes of the chip body 2, thereby realizing the electrical signal connection between the chip body 2 and the leads 5.

[0041] Step S4: Apply adhesive paste 4 into the annular groove defined by the tube shell 6, the base 3 and the chip body 2 and surround the chip body 2, and sinter the adhesive paste 4 to form the chip body 2.

[0042] Since the chip body 2 is located at the center of the pressure sensor and is surrounded by the housing 6, with the base 3 located below the chip body 2, the inner wall of the housing 6, the top surface of the base 3, and the outer surface of the chip body 2 can together form an annular groove. Applying the adhesive paste 4 into this annular groove fills it, allowing the adhesive paste 4 to simultaneously bond to the inner wall of the housing 6, the top surface of the base 3, and the outer surface of the chip body 2. Then, a sintering process is used to simultaneously sinter the adhesive paste 4 and the conductive paste 9 at the same temperature, thereby enabling the adhesive paste 4 to bond the chip body 2 to the housing 6 and the base 3, improving the bonding strength. This process eliminates the need to apply the adhesive paste 4 to the side of the chip body 2 closest to the base 3, avoiding the difficulties, complexity, and high cost associated with screen printing. Furthermore, the adhesive paste 4 fills the gaps between the base 3 and the housing 6, and between the base 3 and the chip body 2, thereby improving the airtightness and reliability of the leadless packaged high-temperature pressure sensor.

[0043] Step S5: Securely connect the cap 1 and the tube shell 6.

[0044] One of the cap 1 and the shell 6 is provided with an annular step. For example, the annular step is provided on the shell 6, so that the cap 1 can be installed on the annular step of the shell 6, and the cap 1 and the shell 6 can be welded together by laser welding to achieve a fixed connection between the cap 1 and the shell 6.

[0045] Step S3 further includes step S31: A positioning groove 300 is formed on the side of the base 3 facing the cap 1, and the chip body 2 is housed in the positioning groove 300.

[0046] By forming a positioning groove 300 on the side of the base 3 facing the cap 1, the chip body 2 can be positioned in the positioning groove 300 to prevent the chip body 2 from moving. This makes it easier to insert the lead wire 5 into the connection hole of the chip body 2, thereby improving the alignment efficiency of the lead wire 5.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0048] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-positioning, leadless packaged high-temperature pressure sensor, characterized in that, The device includes a cap, a base, a chip body, an adhesive paste, leads, and a housing. The cap and the housing are joined together to form a cavity. The base and the chip body are both disposed within the cavity, with the chip body located on one side of the base. The inner wall of the housing, the base, and the chip body together define an annular groove. The adhesive paste is disposed within the annular groove. The leads pass through the housing and the base, respectively, and are connected to the chip body.

2. The leadless packaged high-temperature pressure sensor according to claim 1, characterized in that, The base has a positioning part recessed into the base on the side facing the cap, and the chip body is disposed on the positioning part.

3. The leadless packaged high-temperature pressure sensor according to claim 2, characterized in that, The shape of the positioning part is adapted to the shape of the chip body. The positioning part is a positioning groove, and the cross-sectional shape of the positioning groove and the cross-sectional shape of the chip body are both rectangular.

4. The leadless packaged high-temperature pressure sensor according to claim 1, characterized in that, The thickness of the adhesive slurry ranges from 0.1 mm to 0.3 mm.

5. The leadless packaged high-temperature pressure sensor according to claim 1, characterized in that, The adhesive paste has a through hole extending along the thickness direction of the chip body. The adhesive paste is fitted onto the outer wall of the chip body so that the chip body protrudes through the through hole in a direction away from the base.

6. The leadless packaged high-temperature pressure sensor according to claim 1, characterized in that, The thermal expansion coefficients of the cap, the shell, the base, the adhesive paste, and the chip body are matched.

7. The leadless packaged high-temperature pressure sensor according to claim 1, characterized in that, The number of leads is multiple leads. The base has through holes that extend along the thickness direction of the base. Each through hole corresponds to one of the leads. The chip body has connection holes on the side facing the base that correspond to each of the leads. The leads pass through the through holes and extend into the connection holes. The connection holes are filled with conductive paste.

8. The leadless packaged high-temperature pressure sensor according to claim 1, characterized in that, The inner wall of the tube shell is provided with a stepped portion, and the base is disposed on the stepped portion.

9. A method for manufacturing a self-positioning, leadless packaged high-temperature pressure sensor, characterized in that, The manufacturing method includes: Provides cap, chip body, base, leads and casing; The lead wire is passed through the base and assembled into the tube shell, and the tube shell, base and lead wire are sintered into one piece; Connect the chip body to the base and connect it to the leads; The adhesive slurry is applied into the annular groove defined by the shell, the base and the chip body and surrounds the chip body, and the adhesive slurry is sintered and formed. Secure the cap and the casing together.

10. The manufacturing method according to claim 9, characterized in that, The step of positioning the chip body onto the base and connecting it to the lead wire includes: A positioning groove is formed on the side of the base facing the cap, and the chip body is housed in the positioning groove.

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