A packaging structure for a strain gauge and a pressure sensor, and the pressure sensor thereof.

Abstract

This utility model discloses a strain gauge, a pressure sensor packaging structure, and a pressure sensor. The strain gauge includes multiple strain gauge units so that multiple pressure sensors can be obtained by printing onto a substrate. The strain gauge can be divided into multiple square regions corresponding to the multiple strain gauge units. The shape of each strain gauge unit is consistent with the shape of the four corners of the square region being removed, so that each strain gauge unit is octagonal. The strain gauge has a strain gauge blind slit at the dividing line of the multiple square regions.

Description

Technical Field

[0001] This utility model relates to the field of pressure detection, and in particular to a strain gauge, a pressure sensor packaging structure, and a pressure sensor. Background Technology

[0002] Absolute pressure ceramic pressure sensors, as a new type of strain gauge pressure sensor, are playing an increasingly important role in many fields such as automotive, industrial control, and aerospace due to their unique performance advantages. They are primarily developed using the piezoresistive and force-sensitive effects of thick-film resistors. Specifically, the strain gauge is a thick-film ruthenium salt resistor with a piezoresistive effect, which is directly printed and sintered onto a ceramic elastomer using thick-film processing technology and then assembled, thereby achieving accurate pressure detection.

[0003] Currently, the common manufacturing method for absolute pressure ceramic pressure sensors is mainly based on thick-film printing technology. In this process, the fabrication of the thick-film resistor is particularly crucial. However, existing thick-film printing processes face several pressing problems in practical applications. During printing, if the printing area is too large, it is difficult to ensure the uniformity of the screen printing and the stability of the sheet size. Conversely, if the printing area is too small, it will affect production efficiency to some extent. Furthermore, to improve sheet accuracy, some manufacturing processes use laser-pre-cut ceramic sheet arrays for printing and sheeting, but this method places extremely high demands on the screen printing and sheeting processes. Slight errors can easily lead to problems such as excessive zero-point output voltage and poor sheet size, resulting in inaccurate product calibration or even assembly failure. These problems severely affect the production quality and yield of absolute pressure ceramic pressure sensors, limiting their application and development in a wider range of fields. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model aims to provide a packaging structure for a strain gauge and a pressure sensor, as well as a pressure sensor in general, which can achieve better printing uniformity, stress control, panelization accuracy, and assembly reliability.

[0005] The technical solution of this utility model is implemented as follows: In a first aspect, the present invention provides a strain gauge comprising a plurality of strain gauge units, which are printed onto a substrate to obtain a plurality of pressure sensors. The strain gauge is capable of being divided into a plurality of square regions corresponding to the plurality of strain gauge units. The shape of each strain gauge unit is consistent with the shape of the four corners of the square region being removed, such that each strain gauge unit is octagonal. The strain gauge has a strain gauge blind slit formed at the boundary line of the plurality of square regions.

[0006] In some examples, the plurality of strain gauge units are distributed in a 3×3 array.

[0007] Secondly, embodiments of this utility model provide a packaging structure for a pressure sensor, the packaging structure comprising: According to the strain gauge described in the first aspect; and The strain gauge is printed onto the substrate.

[0008] In some examples, the substrate is formed as follows: The first substrate blind slot corresponding to the strain gauge blind slot; and Base through seam, The first base blind slit and the base through slit together divide the base into a plurality of first base units corresponding to the plurality of square regions of the strain gauge.

[0009] In some examples, the strain gauge blind slot and the first substrate blind slot have the same opening direction.

[0010] In some examples, the substrate is formed with a second substrate blind seam, which serves to provide a positioning reference for the substrate.

[0011] In some examples, the substrate is formed with through holes for inserting conductive terminals.

[0012] In some examples, the encapsulation structure further includes a glass sealing layer between the strain gauge and the substrate.

[0013] In some examples, the substrate is composed of a plurality of second substrate units, each having the same shape as the corresponding strain gauge unit.

[0014] Thirdly, this utility model embodiment provides a pressure sensor, which is obtained by segmenting the packaging structure of the pressure sensor according to the second aspect.

[0015] This utility model provides a packaging structure for a strain gauge and a pressure sensor, as well as a pressure sensor. The strain gauge blind slit releases internal stress during the printing stage, ensuring uniform film thickness and high zero-point accuracy. The octagonal unit reduces warping by eliminating corners and maintaining flatness. The strain gauge blind slit also serves as a slitting line, ensuring accurate slitting dimensions in one go. Large-area printing does not sacrifice uniformity, thus increasing production capacity. Attached Figure Description

[0016] Figure 1 This is a schematic top view of a strain gauge according to an embodiment of the present invention; Figure 2 This is a schematic top view of the packaging structure according to an embodiment of the present invention; Figure 3This is a schematic top view of the base according to an embodiment of the present invention; Figure 4 This is a schematic top view of a base according to another embodiment of the present invention. Detailed Implementation

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0018] When mass-producing absolute pressure ceramic pressure sensors using thick film printing technology, the entire strain gauge needs to be printed onto the ceramic substrate, resulting in significant differences in the thickness of the paste between the edge and the center. This leads to large zero-point drift in the individual sensors obtained by subsequent segmentation. If the printing area per print is reduced, production efficiency must be decreased.

[0019] In view of this, see Figure 1 This utility model provides a strain gauge 10, which may include multiple strain gauge units 11, such as in... Figure 1 The example shown in the image depicts nine strain gauge units 11, which are used to obtain a corresponding plurality of pressure sensors 100 by printing onto a substrate 20, wherein the substrate 20 is... Figure 3 and Figure 4 The pressure sensor 100 is shown in the diagram and will be described in detail below. Figure 2 As shown in the diagram and described in detail below, the strain gauge 10 can be divided into multiple square regions SA corresponding to the plurality of strain gauge units 11. Figure 1 The area filled by the cross-section lines shows a single square region SA. The shape of each strain gauge unit 11 can be consistent with the shape of the four corners of the square region SA being removed, so that each strain gauge unit 11 is octagonal. The strain gauge 10 can form a strain gauge blind slot 12 at the boundary line of the multiple square regions SA. Here, "blind slot" refers to a gap in the thickness direction of the strain gauge 10 where the strain gauge 10 is cut to a certain extent but does not cut through the strain gauge 10.

[0020] With strain gauge blind slots 12 formed on the strain gauge 10, even with a large overall area, the local deformability margin provided by the strain gauge blind slots 12 can effectively absorb the internal stress caused by screen tension or paste shrinkage, avoiding film thickness differences. Under the same printing parameters, the strain gauge 10 with strain gauge blind slots 12 has a more uniform thick film resistance thickness, directly leading to improved accuracy of the zero-point output voltage. Each strain gauge unit 11 is octagonal by removing the four corners of the square region SA, eliminating high stress concentration points in the traditional right-angle region. After stress release, the warpage of the entire strain gauge 10 and individual strain gauge units 11 is reduced, and the flatness of the printed surface is improved. The strain gauge blind slots 12 maintain structural integrity during the printing stage, while becoming a "pre-set break line" during the sheet separation stage. The sheet separation tooling only needs to apply a small external force along the strain gauge blind slots 12 to achieve neat separation, ensuring dimensional consistency. Because the strain gauge blind slit 12 allows the entire strain gauge 10 to be screen-printed over a large area first, and then divided into pieces at once, the printing area of ​​a single batch is increased without sacrificing uniformity, and the number of sensors produced per unit time is increased.

[0021] In summary, through the structure of strain gauge 10 (including strain gauge blind slot 12) and octagonal strain gauge unit 11, this embodiment achieves an unprecedented balance between printing uniformity, stress control, segmentation accuracy and assembly reliability, significantly improving the accuracy of zero-point output voltage and reducing overall manufacturing costs.

[0022] According to the embodiments of this utility model, obtaining the strain gauge 10 can be divided into the following steps: initial preparation of the gauge body and processing of its shape and blind seam.

[0023] For the initial sheet preparation, high-purity alumina ceramic powder is selected, and square initial strain gauges with uniform thickness are obtained through one of two conventional processes. One process is the dry pressing method, in which the powder is filled into a mold and pressed into a green body of the required thickness under high pressure in one step, followed by high-temperature sintering for shaping. The other process is the solution casting method, in which ceramic slurry is uniformly coated onto a carrier film, and after drying, lamination, isostatic pressing, and high-temperature sintering, a dense and uniformly thick square ceramic sheet is obtained.

[0024] For the shape and blind seam processing, two tasks are completed on the sintered square initial strain gauge: corner removal and strain gauge blind seam 12 formation. For corner removal, the four corners of each preset square region SA are cut off, so that each future strain gauge unit 11 has an octagonal profile. For strain gauge blind seam 12 formation, non-penetrating or semi-penetrating cuts are made at the common boundary of each square region SA, leaving continuous grooves, which are the strain gauge blind seams 12. The strain gauge blind seams 12 maintain the integrity of the entire structure during printing and handling, and also serve as the preset break path during subsequent sheet separation.

[0025] Through the above steps, a strain gauge 10 with an octagonal strain gauge unit 11 and a built-in strain gauge blind slit 12 can be obtained in one go, providing a ceramic substrate with high consistency and high yield for subsequent thick film printing, packaging and slab separation processes.

[0026] In embodiments according to the present invention, such as in Figure 1 As shown, the plurality of strain gauge units 11 can be distributed in a 3×3 array.

[0027] With a 3×3 array (i.e., 9 strain gauge units 11), the printing area of ​​a single strain gauge 10 is controlled within an optimal range: large enough to print 9 sets of thick-film resistors simultaneously in one stroke, yet not too large to avoid uneven film thickness caused by paste dripping. Since each strain gauge unit 11 is octagonal, the stress concentration areas at the four corners are eliminated. Combined with the release of internal stress during the printing stage via the strain gauge blind slots 12, the warpage height of the entire strain gauge 10 is suppressed, meeting the stringent zero-drift requirements of high-end absolute pressure sensors. The strain gauge blind slots 12 corresponding to the 3×3 array are in a grid shape, dividing the entire strain gauge 10 into 9 independent but temporarily connected units. During separation, the tooling only needs to cut along the strain gauge blind slots 12 once to complete the simultaneous separation of the 9 units, reducing the separation time per unit. Simultaneously, the preset depth of the strain gauge blind slots 12 ensures a neat break line, keeping the separation size error within a small range, ensuring proper alignment with the substrate 20 and significantly improving assembly yield.

[0028] See Figure 2 This utility model embodiment also provides a pressure sensor packaging structure 1, which may include: According to the strain gauge 10 of the foregoing embodiments of this utility model, as in Figure 2 The area filled with dots is schematically shown, and its outline is shown as a dashed line; and The strain gauge 10 is printed onto the substrate 20, on Figure 2 The outline of the middle substrate 20 is shown by solid lines to distinguish it from the strain gauge 10.

[0029] The encapsulation structure 1 integrally encapsulates the strain gauge 10 and the substrate 20. After segmenting the encapsulation structure 1 of the pressure sensor, multiple independent pressure sensors 100 can be obtained, such as in... Figure 2 As shown in the diagram, nine independent pressure sensors 100 can be obtained.

[0030] In embodiments according to this utility model, see Figure 3 and combined Figure 2 The substrate 20 can be formed with: The first substrate blind slot 22 corresponding to the strain gauge blind slot 12; and Base through seam 23, Among them, the first base blind slit 22 and the base through slit 23 together divide the base 20 into a plurality of first base units 21 corresponding to the plurality of square regions SA of the strain gauge 10, as shown in Figure 3 The area filled by the cross-section lines shows a single first base unit 21.

[0031] Like the strain gauge blind slot 12, the first base blind slot 22 facilitates segmentation while maintaining the integrity of the base 20. The base through slot 23 directly corresponds to the area in the strain gauge 10 where the corners have been removed. During the segmentation of the packaging structure 1 to obtain independent pressure sensors 100, complete separation can be achieved without any additional laser or mechanical cutting, completely eliminating dimensional drift caused by secondary processing. Thus, the portion outlined by the base through slot 23 can be used as the mating part of the pressure sensor 100, ensuring assembly accuracy. Furthermore, when the first base blind slot 22 and the base through slot 23 together divide the base 20 into multiple first base units 21 corresponding to the multiple square regions SA of the strain gauge 10, the processing of the first base blind slot 22 and the base through slot 23 is easier to achieve because they are on the same straight line, reducing the need for adjustments to the processing path.

[0032] In embodiments of the present invention, the opening directions of the strain gauge blind slit 12 and the first substrate blind slit 22 may be the same.

[0033] The strain gauge blind slot 12 and the first substrate blind slot 22 have the same opening direction, forming a continuous weak line with the highest stress concentration coefficient in the thickness direction of the encapsulation structure 1. The segmentation tooling only needs to apply a bending moment in a single direction along this weak line to break the entire encapsulation structure 1 into multiple independent pressure sensors 100.

[0034] In embodiments according to this utility model, see Figure 3 The substrate 20 may have a second substrate blind seam 24, which is used to provide a positioning reference for the substrate 20.

[0035] Before thick film printing, the vision system of the screen printing machine can quickly identify the orientation of the substrate 20 and perform mechanical correction using the second substrate blind slit 24 as a coordinate reference. Since the relative positions of the second substrate blind slit 24 and the strain gauge blind slit 12 are fixed in the design, the subsequent pattern offset of the strain gauge unit 11 can be controlled through the second substrate blind slit 24, directly ensuring the symmetry of the resistance bridge circuit. The second substrate blind slit 24 is located at a specific position on the substrate 20, forming an asymmetrical geometric feature. The positioning unit on the segmentation fixture can cooperate with the second substrate blind slit 24, ensuring that the substrate 20 is fully positioned only when placed in the fixture in the correct orientation. For example, reversing or rotating 90° will be judged as incorrect positioning, completely eliminating batch mixing and orientation errors. The independent pressure sensor 100 can also retain the second substrate blind slit 24 as an orientation marker; for example, the installation orientation of the pressure sensor 100 can be confirmed by manual visual inspection. In summary, by introducing a second substrate blind seam 24 into the substrate 20, this embodiment achieves "one-time positioning and full-process error prevention" throughout the entire process of printing, slitting, assembly, and after-sales service. This significantly shortens the cycle time, improves the yield, and reduces labor and equipment debugging costs, providing key support for the large-scale, high-reliability manufacturing of the pressure sensor 100.

[0036] In an embodiment of the present invention, the substrate 20 may have a through hole 25 for inserting a conductive terminal.

[0037] In this embodiment, the substrate 20 has through holes 25 in each first substrate unit 21, allowing conductive terminals to be directly inserted and electrically connected to the thick-film resistor, thereby "activating" the independent pressure sensor 100 in one step. Specifically, after the conductive terminals are inserted into the through holes 25, they can be electrically connected to the thick-film resistor bridge on the strain gauge 10 by one-time sintering with glass solder or silver paste, without the need for additional wire bonding or patching, reducing process steps and thus lowering production costs. Combining "conductive terminal insertion" and "ceramic packaging" into one significantly improves the pressure sensor 100 in terms of functionality, size, reliability, and cost, truly realizing a highly efficient manufacturing mode of "one-time molding, plug and play".

[0038] In an embodiment of the present invention, the encapsulation structure 1 may further include a glass sealing layer between the strain gauge 10 and the substrate 20.

[0039] In this embodiment, the glass sealing layer is placed between the strain gauge 10 and the substrate 20, completing the traditional "adhesive" function. In addition, the glass sealing layer softens and fills the microscopic gaps between the strain gauge 10 and the substrate 20 during the sintering process, forming a continuous and dense glass-ceramic interface, which reduces the leakage rate, meets the airtight requirements for long-term operation under pressure, eliminates the need for additional metal welding rings, reduces the number of structural components, and shortens the assembly process.

[0040] In embodiments according to this utility model, see Figure 4 and combined Figure 1 The substrate 20 may be composed of a plurality of second substrate units 26, each of which has the same shape as the corresponding strain gauge unit 11.

[0041] In this case, the same function as the base through-slit 23 described above can be achieved by removing the corner. Specifically, in the process of dividing the packaging structure 1 into pieces to obtain the independent pressure sensor 100, the part where the corner is removed can be completely separated without any additional laser or mechanical cutting, completely eliminating dimensional drift caused by secondary processing. Similarly, the part where the corner is removed can be used as a mating part of the pressure sensor 100, which can ensure assembly accuracy.

[0042] The aforementioned substrate 20 can also be obtained in a similar manner to strain gauge 10. For example, the initial sheet body can be prepared by dry pressing or solution casting. The first substrate blind slit 22, the substrate through slit 23, the second substrate blind slit 24, and the through hole 25 can be obtained by laser cutting or mechanical cutting.

[0043] See Figure 2 This utility model embodiment also provides a pressure sensor 100, which can be obtained by segmenting the packaging structure 1 of the pressure sensor according to the foregoing embodiments of this utility model.

[0044] In this embodiment, the pressure sensor 100 is directly obtained from the packaging structure 1 through a single slab process. The strain gauge 10, glass sealing layer, and substrate 20 in the packaging structure 1 have been co-fired together at high temperature in one step. After slab separation, the pressure sensor 100 has an octagonal strain gauge unit 11, a first substrate unit 21, and a through hole 25, forming a three-in-one micro-module of "pressure sensing-sealing-electrical connection". It does not require secondary patching or adhesive application, and its thickness and overall volume are both small, providing a scalable miniaturized solution for absolute pressure detection scenarios.

[0045] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A strain gauge comprising a plurality of strain gauge units for obtaining a plurality of corresponding pressure sensors by printing onto a substrate, characterized in that, The strain gauge can be divided into multiple square regions corresponding to the plurality of strain gauge units. The shape of each strain gauge unit is consistent with the shape of the four corners of the square region after they have been removed, so that each strain gauge unit is octagonal. The strain gauge has a strain gauge blind slit at the boundary line of the multiple square areas.

2. The strain gage according to claim 1, wherein The multiple strain gauge units are distributed in a 3×3 array.

3. A packaging structure for a pressure sensor, characterized in that, The packaging structure include: The strain gauge according to claim 1 or 2; and The strain gauge is printed onto the substrate.

4. The package structure of claim 3, wherein, The substrate is formed with: The first substrate blind slot corresponding to the strain gauge blind slot; and Base through seam, The first base blind slit and the base through slit together divide the base into a plurality of first base units corresponding to the plurality of square regions of the strain gauge.

5. The package structure of claim 4, wherein, The strain gauge blind slit and the first substrate blind slit have the same opening direction.

6. The package structure of claim 3 or 4, wherein, The substrate has a second substrate blind seam, which is used to provide a positioning reference for the substrate.

7. The package structure of claim 3 or 4, wherein, The substrate has through holes for inserting conductive terminals.

8. The package structure of claim 3 or 4, wherein, The encapsulation structure also includes a glass sealing layer between the strain gauge and the substrate.

9. The package structure of claim 3, wherein, The substrate is composed of a plurality of second substrate units, each of which has the same shape as the corresponding strain gauge unit.

10. A pressure sensor, characterized by The pressure sensor is obtained by segmenting the packaging structure of the pressure sensor according to any one of claims 3 to 9.

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