Pressure measuring device and method for producing a pressure measuring device
The pressure measuring device with a metallic support, glass base, and silicon sensor, utilizing an annular recess and laser ablation, addresses reproducibility issues by minimizing thermal stress and manufacturing irregularities, resulting in consistent and efficient pressure measurement.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ENDRESS & HAUSER GMBH & CO KG
- Filing Date
- 2025-11-24
- Publication Date
- 2026-06-18
AI Technical Summary
Existing pressure measuring devices face challenges in reproducibility due to manufacturing irregularities, material splintering during sawing, and material selection affecting pressure transfer, leading to inconsistent pressure measurement.
A pressure measuring device with a metallic support, glass base, and silicon pressure sensor, featuring a central axis, annular recess, and support extension for thermal decoupling, combined with laser ablation for precise contouring and stacking, ensuring minimal thermal stress and improved reproducibility.
The solution enhances reproducibility and reduces thermal stress, allowing for efficient production of pressure measuring devices with consistent performance and reduced manufacturing defects.
Smart Images
Figure EP2025083965_18062026_PF_FP_ABST
Abstract
Description
[0001] Pressure measuring device and method for manufacturing a pressure measuring device
[0002] The present invention relates to a pressure measuring device and a method for manufacturing a pressure measuring device.
[0003] DE 10 2015 117 736 A1 discloses in Fig. 2 a generic pressure measuring device with a centrally arranged recess in a base and two edge support feet.
[0004] Fig. 2 shows an idealized form. In reality, for example, a ceramic base cannot be manufactured with an optimally flat surface using a conventional ceramic pressing or sintering process. In practical applications, glass bodies are usually shaped by sawing. Sawing out a recess can lead to splintering and potentially material breakage if the sawing is too deep within the usual manufacturing precision. Compensation for unevenness and splintering can often be achieved by adjusting the thickness of the joint. Overall, the reproducibility of such a pressure measuring device is rather low.
[0005] Another design challenge illustrated in Fig. 2 arises from the fact that pressure is transferred via the extension to an underlying cavity. With an unfavorable material selection, the base can act like a second membrane. This can affect pressure measurement and reproducibility during manufacturing.
[0006] Based on the aforementioned prior art, the object of the present invention is to provide an improved pressure measuring device with higher reproducibility.
[0007] The present invention solves the problem by means of a pressure measuring device with the features of claim 1 and by means of a method for manufacturing such a pressure measuring device with the features of claim 10.
[0008] The pressure measuring device according to the invention can be used to determine an absolute pressure, a relative pressure or a differential pressure.
[0009] It comprises a support, in particular a metallic support, a base connected to the support and a pressure sensor mounted on a freestanding end of the base.
[0010] The pressure measuring device has a central axis. This central axis can also be designed as an axis of symmetry.
[0011] The base has an end face facing the support, which is connected to an end face of the support facing the base by means of a joint.
[0012] The side of the base facing the support has an annular recess located between the support and the base. This recess is bounded radially inwards by a support extension. The recess has a base surface that extends essentially in a plane perpendicular to the central axis. Manufacturing-related roughness, which may exhibit slight irregularities in the base surface, is negligible.
[0013] The end face of the base facing the support is at least partially provided by the support extension. The reduced thermal stress towards the support is achieved through this support extension. Simultaneously, the support extension is also thermally decoupled from the support along its radial edge surfaces by the recess. In the aforementioned SdT, however, the edge surfaces of the support (as shown in Fig. 3) rest against the base, or a minimal annular gap exists. This significantly increases the heat transfer between the support and the base compared to the variant according to the invention.
[0014] Further advantageous embodiments are the subject of the dependent claims.
[0015] In a particularly preferred embodiment, the ring-shaped recess is arranged in the base and opens towards the support.
[0016] It is bounded radially outwards from the central axis by a projection. Furthermore, as already explained, it is bounded radially inwards by a supporting extension.
[0017] The end face of the base facing the support is divided into at least two spatially separate sub-areas, with a first sub-area being provided by the projection and a second sub-area being provided by the support extension.
[0018] The spatial division of the end face achieves even more optimized thermal decoupling from the support structure. Furthermore, the recess is supported by the support extension, preventing any deflection under pressure on the pressure membrane.
[0019] It is advantageous if the outer contours of the base and the pressure sensor have an identical radial distance to the central axis, particularly on all sides. This allows for production-efficient cutting across multiple plate levels of the aforementioned components of the pressure measuring device. This cutting process can be combined with the contouring of the base's end face, resulting in particularly efficient manufacturing.
[0020] The projection and the ring-shaped recess can be designed as a square ring for particularly efficient support. This allows the pressure sensor to retain its previously used rectangular shape.
[0021] The support extension can be designed as a pipe extension, particularly for differential pressure measurement, wherein the pipe extension has an internal fluid line that is designed as a section of the pressure transmission line, which extends from a pressure chamber in the pressure sensor through the base and through the support.
[0022] The pressure sensor can be made primarily of silicon, and the carrier of stainless steel. For electrical insulation, the base is made of glass, preferably borosilicate glass, preferably with a borosilicate content of more than 50 wt.%. The borosilicate glass may contain typical additives to modify the properties of the glass, e.g., brittleness and hardness.
[0023] The pressure transmission line can have a uniform diameter along its route from the support to the pressure chamber.
[0024] Furthermore, at least one of the sections of the base's end face can have a minimum width or web width of less than 0.7 mm, preferably between 0.3 and 0.5 mm. The web width should be less than 0.7 mm for particularly efficient reduction of thermal stresses. Since material removal by laser ablation only allows the production of vertical web walls for the projection or support extension, these should have a minimum width of 0.3 mm.
[0025] To ensure sufficient mechanical stability during the laser ablation process and the associated heat input, the material thickness in the area of the projection should be at least 0.6 mm, preferably 0.7 to 2.5 mm. The depth tolerance resulting from the laser ablation can, particularly preferably, be less than ±150 µm in the area of the base surface.
[0026] The recess created by laser profiling can be formed with a positional accuracy of less than 30 pm, preferably 10-25 pm. This is associated with a certain surface roughness of the laser profiling.
[0027] Furthermore, according to the invention, a method for manufacturing a pressure measuring device, preferably a pressure measuring device according to one of the preceding claims, comprises a silicon-based semiconductor pressure sensor with a measuring membrane and a membrane carrier, a metallic carrier and a base made of glass, which is arranged in a stack for electrical insulation between the pressure sensor and the carrier, wherein the method comprises the following steps:
[0028] A. Providing and contouring a first and / or a second silicon plate, forming the end faces of a measuring membrane and a membrane carrier facing each other in the stacking direction to form a pressure chamber, wherein the contouring is carried out by a laser ablation process; and a glass plate, forming an end face of the base facing the carrier and a pressure sensor;
[0029] Contouring the end face of a glass plate was not possible using the previously common method of sawing. B. Stacking and joining the first silicon plate, the second silicon plate, and the glass plate to form a plate stack, including the formation of joining points for the pressure measuring device;
[0030] Previously, the individual layers of the pressure measuring device were manufactured separately and then stacked. A plate-by-plate arrangement followed by singulation reduces manufacturing effort and increases the dimensional accuracy of the individual layer positioning. This results in a pressure measuring device with improved measurement performance and reproducibility, while significantly reducing thermal stress.
[0031] C. Singling out a pressure sensor base assembly from the stack of plates and
[0032] Singulation can be achieved, for example, by sawing or laser cutting.
[0033] D. Material-locking fixing of an end face of a glass base of the pressure sensor base assembly onto the carrier, forming the pressure measuring device.
[0034] This fixing is achieved in a joining process, preferably by means of a thin adhesive layer between the carrier and the base.
[0035] Further advantageous embodiments of the method are the subject of the dependent claims.
[0036] It is advantageous if one or all silicon plates and / or the glass plate have positioning aids, such as openings, outside of a surface contoured area.
[0037] The contouring in step A is carried out using a laser ablation process to achieve better dimensional accuracy of the fine contouring of the front surface.
[0038] The singulation in step e can be carried out by sawing the stacked plates arranged on top of each other, providing a plurality of singulated pressure sensor base assemblies.
[0039] Further advantageous features are explained below.
[0040] The base can include a base mounted on the support; furthermore, the base can include an extension extending from the base towards the pressure sensor, encompassing the free end of the base; the base can have a surface area larger than the surface area of the extension; and the extension can have a surface area smaller than the surface area of the pressure sensor mounted on it. This allows for a reduction in thermal stress between the pressure sensor and the base.
[0041] A first embodiment provides that an end face of the base facing the support, in particular an end face of the base facing the support or an end face of a second extension of the base adjacent to the base facing the support, is connected by means of a joint to an end face of the support facing the base, in particular a bottom surface of a recess in the support, and an end face of the extension facing the pressure sensor is connected by means of a joint to an end face of the pressure sensor facing the base.
[0042] A further preferred embodiment of the first embodiment provides that at least one of the joints, in particular both joints, are adhesive joints, in particular adhesives made with an epoxy resin-based adhesive, a thermoplastic adhesive or a silicone adhesive, in particular a silicone rubber.
[0043] A second embodiment provides that the base is essentially disc- or ring-shaped, has a height on the order of 0.5 mm to 10 mm, and / or has an essentially circular base whose outer diameter is larger than an outer diameter of the extension and in particular is less than 10 mm, or has an essentially square or rectangular base whose side lengths are larger than an outer diameter of the extension and in particular are less than 10 mm.
[0044] A third embodiment provides that the extension is tubular or rod-shaped, wherein the extension has in particular a circular or annular base, in particular a base with an outer diameter in the range of 0.5 mm to 5 mm, and the extension has a freestanding length which is greater than or equal to a minimum length of a few tenths of millimeters, and in particular is on the order of 0.5 mm.
[0045] A fourth embodiment provides that the pressure transmission line, which runs through the support and the base, through which the pressure sensor can be subjected to a pressure or a reference pressure, and which in particular has an inner diameter in the range of 0.25 mm to 1 mm.
[0046] To achieve a particularly effective reduction of the contact area and, if necessary, thermal decoupling along the radial contact surfaces, it is advantageous if the base surface extends radially from the central axis over at least 5%, preferably at least 10%, and most preferably between 30-90% of the maximum radial extent of the base.
[0047] Initial training stipulates that the base is placed in an exclusion zone within the organization.
[0048] A further development of the second embodiment provides that the recess has a height of greater than or equal to 0.2 mm in an axial direction parallel to the longitudinal axis of the extension, in particular a height in the range of 0.2 mm to 0.5 mm. A further embodiment of the invention provides that a cavity is provided which surrounds a joint between the base and the support on all sides from the outside, wherein the cavity is formed in particular by an outer lateral surface of the base having a shape that reduces the cross-sectional area of the base in the direction of the support, in particular by a conically tapered shape, at least on its side facing the support.
[0049] A fourth further development stipulates that the pressure measuring device is a differential pressure measuring device or an absolute or relative pressure measuring device for measuring higher pressures, in particular pressures of greater than or equal to 4 MPa, and that the base is made of a material that has a modulus of elasticity of greater than or equal to 200000 MPa.
[0050] The invention and its advantages will now be explained in more detail using the figures. They show:
[0051] Fig. 1 shows a sectional view of a first pressure measuring device according to the invention;
[0052] Fig. 2 shows a block diagram of an embodiment of the method according to the invention;
[0053] Fig. 3 shows a sectional view of a second pressure measuring device according to the invention; and
[0054] Fig. 4 shows a sectional view of a third pressure measuring device according to the invention.
[0055] Figure 1 shows a pressure measuring device 1 according to the invention. It comprises a carrier 2, a base 3 connected to the carrier 2, and a pressure sensor 4 mounted on a free end of the base 3. The pressure sensor 4 is a so-called semiconductor pressure sensor, e.g., a silicon-based pressure sensor chip. It has, for example, a diaphragm carrier 5 and a measuring diaphragm 6 arranged thereon, beneath which a pressure chamber is enclosed. The pressure chamber is bounded at its bottom by a diaphragm carrier 5. The pressure measuring device 1 can be configured as a differential pressure, a relative pressure, or an absolute pressure measuring device. The measuring diaphragm 6 has, in a functionally typical manner, a peripheral support area 8 and a central segment 26 with a reduced wall thickness compared to the support area. The pressure measuring device has a central axis 100.This central axis 100 can also be designed as an axis of symmetry.
[0056] To measure differential pressures, a first side of the measuring diaphragm 6 is subjected to a first pressure p1, and its second side is subjected to a second pressure p2 via a pressure transmission line 9 (shown as a dashed line in Fig. 1) that runs through the support 2, the base 3, and the diaphragm support 5 and opens into the pressure chamber 7. In this embodiment, the pressure difference acting on the measuring diaphragm 6 between the first and second pressures p1, p2 causes a deflection of the measuring diaphragm 6 that depends on the differential pressure Ap to be measured.
[0057] To measure relative pressures, the first side of the measuring diaphragm 6 is subjected to the pressure p to be measured, and a reference pressure, e.g., ambient pressure, is applied to the second side of the measuring diaphragm 6 instead of the second pressure p2. This reference pressure serves as the reference against which the pressure p acting on the first side is to be measured. In this embodiment, the pressure difference acting on the measuring diaphragm 6 between the pressure p and the reference pressure causes a deflection of the measuring diaphragm 6 that depends on the relative pressure to be measured.
[0058] In both differential pressure measuring devices and relative pressure measuring devices, the pressure transmission line 9 preferably has an inner diameter on the order of 0.25 mm to 1 mm. Ideally, the inner diameter of the pressure transmission line is uniform or varies with minor deviations of less than 20% of the average inner diameter along its length.
[0059] To measure absolute pressures, the pressure chamber 7 enclosed beneath the measuring diaphragm 6 is evacuated and completely sealed off from the outside by the measuring diaphragm 6 and the diaphragm support 5. In this case, the pressure transmission line 9, which runs through the support 2, the base 3, and the diaphragm support 5 and opens into the pressure chamber 7, is omitted, and the pressure p acting on the first side of the measuring diaphragm 6 causes a deflection of the measuring diaphragm 6 that depends on the absolute pressure to be measured.
[0060] In all three cases, the resulting deflection of the measuring membrane 6 is detected by means of an electromechanical transducer and converted into an electrical output signal, which is then available for further processing and / or evaluation. For example, a piezoresistive transducer can be used as the transducer, comprising sensor elements 10 arranged on or in the measuring membrane 6, e.g., piezoresistive elements connected together to form a resistance measuring bridge.
[0061] The illustrated pressure measuring device is designed such that its base 3 comprises a base 12 arranged on the support 2 and a projection 13 extending from the base 12 towards the pressure sensor 4. The projection 13 encompasses the free end of the base 3 on which the pressure sensor 4 is mounted.
[0062] For measuring absolute pressures, the extension 13 is preferably rod-shaped, and the base 12 has a substantially disc-shaped geometry. For measuring relative or differential pressures, the extension 13 is preferably tubular, and the base 12 has a substantially annular disc-shaped geometry.
[0063] The extension 13 of the base 3 has an end face 15 facing the pressure sensor 4, which is connected to an end face 16 of the pressure sensor 4 facing the base 3 by means of a joint 14.
[0064] The aforementioned end face 15 of the extension 13 is smaller than the end face 16 of the pressure sensor 4. Semiconductor pressure sensors typically have an end face 16, usually square, the size of which is on the order of 1 mm², depending on the measuring range and sensitivity. 2 up to 100 mm 2The pressure sensor 4 preferably does not extend beyond a radial extent of 15 mm starting from the central axis 100 of the pressure sensor 4.
[0065] In contrast, the extension 13 preferably has a circular or annular end face 15. Depending on the size of the end face 16 of the pressure sensor 4, the outer diameter of the extension 13 is preferably in the range of 0.5 mm to 5 mm. For a rod-shaped extension 13, this corresponds to an end face 15 on the order of approximately 0.2 mm². 2 up to 20 mm 2 .
[0066] The rod- or tube-shaped extension 13 preferably has a free-standing length that is greater than or equal to a minimum length of a few tenths of a millimeter. For example, the extension 13 can have a length on the order of 0.5 mm.
[0067] This geometry, in particular the small base area of the joint 14 in relation to the front surface 16 of the pressure sensor 4, provides a decoupling of the measuring membrane 6 and the carrier 2, which protects the pressure sensor 4 from thermomechanical stresses.
[0068] In the pressure measuring device according to the invention, the base 12 has a base area 17 that is larger, preferably significantly larger, than the end face 16 of the extension 13. If the base 12 is substantially circular or annular disk-shaped, it has an outer diameter that is larger than the outer diameter of the extension 13 and preferably less than 10 mm. If the base 12 has a substantially rectangular or square base area 17, its side lengths are correspondingly larger than the outer diameter of the extension 13 and preferably less than 10 mm. The base 12 has a height H, which, in the substantially disk- or annular disk-shaped geometry shown here, is determined by the disk thickness and is preferably greater than or equal to 0.6 mm and less than or equal to 10 mm.
[0069] The base 3 of the illustrated pressure measuring device each has an end face 18 facing the carrier 2, which is connected to an end face 19 of the carrier 2 facing the base 3 by means of a joint 20.
[0070] Preferably, at least one of the two joints 14 or 20 is an adhesive bond, in particular the adhesive bond 20. In a particularly preferred embodiment, both joints 14 and 20 are adhesive bonds, or the joint between the base 3 and the pressure sensor 4 is eutectic and can be based on borosilicate. This is particularly advantageous if the base is also made of glass, in particular borosilicate glass. Epoxy resin-based adhesives, thermoplastic adhesives, or silicone adhesives, such as silicone rubber, are particularly suitable for producing the adhesive bonds. Other joining techniques, e.g., soldering, can also be used, but are less preferred due to the heat input. In Fig. 1, a recess 21, open towards the support 2, is provided in the base 12 of the base 3 on the side facing the support 2.
[0071] The recess 21 has a height h in the axial direction - i.e. parallel to the longitudinal axis of the extension 13 - which is on the order of 0.2 mm to 0.5 mm, depending on the height H of the base 12.
[0072] In contrast to the variant shown in Fig. 2 of DE 10 2015 117 736, the recess 21 is preferably substantially annular with an annular base 22. The annular recess may preferably have an outer diameter that is smaller than the outer diameter or the side lengths of the base 12. On its outer side, the base 22 is bounded by a projection 23 or several projections, which preferably extend parallel to the central axis 100 from the base in the direction of the support 2. The projection 23 or the assembly of projections forms a terminal portion 18a of the end face 18, which is provided for the joint 20 with the end face 19 of the support 2. Preferably, the projection 23 is arranged circumferentially around the base 22, so that a particularly good all-round seal is achieved by the joint 20.
[0073] Alternatively, the recess 21 can have a substantially square or rectangular annular base 22. The projection has a ring contour of a rectangular ring. This ensures more stable support under axial pressure.
[0074] The base surface 22 is bounded on the inside by a support extension 24, which projects parallel, and in particular concentrically, to the central axis 100 from the base surface 22 in the direction of the beam 2. The support extension 24 provides at its end a further area 18b of the end face 18 for the joint 20 with the end face 19 of the beam 2.
[0075] The outer contour of the support extension 24 can be either cylindrical or prismatic. In the case of an absolute pressure measuring device, the support extension 24 can be manufactured as a solid material element, thus achieving increased support under pressure in the central segment 11 of the base 3.
[0076] In the case of a differential pressure measuring device or relative pressure measuring device, as shown in Fig. 1, the support extension 24 is designed as a pipe extension with an internal fluid line 25 as a section of the pressure transmission line 9. The internal fluid line 25 preferably has a uniform cross-sectional area, which particularly preferably corresponds to the cross-section of the section of the pressure transmission line arranged in the support 2 or the cross-section of the section arranged in the pressure sensor 4.
[0077] In the case of differential pressure or relative pressure measurement, the pipe extension has the advantage of a two-stage seal compared to the variant shown in Fig. 2 of DE 10 2015 117 736 A1. It should be noted that a pressure transmission medium, e.g., oil, is typically arranged around the pressure measuring device. The same applies to the pressure transmission medium arranged in the pressure transmission line 9. These must be separated from each other in a medium-tight manner. Unlike in Fig. 1 of DE 10 2015 117 736 A1, the joints in Fig. 2 of this application are distributed over only a small area. Therefore, the joint is more susceptible to leaks and diffusion effects. By dividing the joints into two sub-areas 18a and 18b, the joint is provided in two spatially separated, preferably concentric, sealing positions, with the recess 21 serving as the spatial separation.Ideally, the recess 21 is designed to be free of damping medium.
[0078] At the same time, the sub-areas 18a and 18b of the support extension and the edge projection 23 can be further reduced to minimize thermomechanical stresses. The division into two spatially separate areas allows for a more optimal stress distribution across the entire joining surface. If, during operation of the pressure measuring device, the seal fails due to localized thermomechanical stresses or insufficient connection between the base 3 and the support 2, the second position 18b of the end face 18 provides a safeguard for the joint 20 between the two aforementioned components.
[0079] Another difference from Fig. 2 of DE 10 2015 117 736 A1 is that the radial extent of the base and the radial extent of the pressure sensor 4, starting from the central axis 100, are the same. This is advantageous from a manufacturing perspective, as it allows the pressure sensor 4 and the base 3 to be cut together, resulting in time savings.
[0080] In order to produce the aforementioned fine division of the end face, a laser ablation method for processing a cuboid blank is particularly preferred, taking into account the maximum radial extent of the pressure sensor 4 starting from the central axis 100 of a maximum of 15 mm.
[0081] Glass, in particular borosilicate glass, is the preferred material used for manufacturing base 3. The use of laser ablation in combination with glass enables particularly precise manufacturing.
[0082] Previously, the ceramic bases predominantly used were manufactured using a fundamentally different process: pressing them into a specific mold. Often, the contact surface was not perfectly flat due to shrinkage and similar factors. This resulted in sealing problems.
[0083] Stainless steel bases are used for connecting a silicon pressure sensor to the
[0084] The stainless steel surface of a support is unsuitable, as both the membrane support 5 and the
[0085] Measuring membrane 6 is made of silicon. Stainless steel is conductive and must be electrically decoupled from the steel surface of the support. Accordingly, an electrical insulator must be used.
[0086] Until now, glass in this application has been shaped by sawing. Surface profiling or contouring could only be achieved to a limited extent by sawing. Saw grooves or similar features are conceivable. High dimensional accuracy was only achievable to a limited degree with glass bases of the aforementioned size. There was an increased risk of splintering during fine-tuning by sawing.
[0087] The laser ablation process enables the production of recesses with a positional accuracy of 20 pm, with a minimum depth of 0.2 mm. The depth tolerance is + / - 100 pm. The glass thickness at the thinnest point of the base 12 in the area of the bottom surface 22 is between 0.6 mm and 3.3 mm.
[0088] The sub-areas 18a and / or 18b can each have a minimum width or a minimum web width of less than 0.7 mm, preferably between 0.3 - 0.5 mm.
[0089] To achieve a compact sensor design and to reduce inclined forces on the joint 20, the base 3 can, preferably completely, be inserted into a recess 27 of the carrier 3.
[0090] The circumferential annular projection 23 and / or the support extension 24 has a uniform rectangular cross-section and thus a uniform width over its entire extent. A projection with a conical cross-section would be mechanically more stable, but this cannot be manufactured using a laser ablation process.
[0091] Fig. 2 shows a process diagram for manufacturing a pressure measuring device according to the invention, in particular a pressure measuring device according to Fig. 1.
[0092] In a first step, 101, it comprises providing a glass plate and contouring an area of the glass plate to form the end faces 18a, 18b and 15, as well as the base surface 22 of the plinth 3, using a laser ablation process. The glass plate may be borosilicate-based and may contain further glass additives to improve its properties.
[0093] The method then comprises a second step 102, the provision of a first silicon plate for the production of a measuring membrane 5, contouring an area for the formation of the pressure chamber 7, preferably also by means of the laser ablation method.
[0094] The method then comprises, in a third step 103, providing a second silicon plate for the fabrication of a membrane support plate 6. The membrane support plate 6 can have grooves for the insertion of grooves, in particular on a side facing the support 2 or the base 3, preferably in a rectangular arrangement, analogous to Fig. 7 of DE 10 2017 127 704 A1, to reduce thermal stresses within the end face 16. The temporal sequence of steps 101-103 can be chosen arbitrarily, so that the third step can be carried out first and only then the first or second step.
[0095] In steps 101-103, pre-contouring or material weakening can also be carried out with regard to the outer circumference of the aforementioned individual components of the pressure measuring device.
[0096] The glass plates can have additional positioning aids for precise stacking. These positioning aids can be, for example, guide openings that can be fixed in position using a telescopic rod.
[0097] It is understood that several identical individual elements of the pressure measuring device 1 can be arranged side by side in a field on the respective glass and / or silicon plate in order to provide a plurality of pressure sensor and base arrangements in a subsequent singulation step.
[0098] The fourth step 104 is therefore the stacking of the aforementioned silicon and / or glass plates to form a pressure sensor and base arrangement.
[0099] The fifth step, 105, is the separation of the pressure sensor and base assembly from the sheet material. In this step, multiple pressure sensor and base assemblies can be separated from a single stack of sheets. This can be done by sawing or laser cutting.
[0100] In particular, a corresponding base 3 can be arranged manually or mechanically on the carrier 2. When arranged mechanically, the comparatively large surface area of the base 12 offers the advantage that the bases 3 can be more easily picked up by a pick-and-place machine and, once picked up, can be transported and subsequently positioned more securely.
[0101] Finally, in a sixth step 106, the respective pressure sensor and base arrangement can be connected to the carrier to form the pressure measuring device 1 by a joining method, in particular by gluing.
[0102] The aforementioned method is particularly well suited for the time-efficient production of the pressure measuring device 1 according to the invention in a mass production process with a low reject rate, while providing a pressure measuring device with consistently high reproducibility.
[0103] The pressure measuring device can, in particular, be part of a larger pressure gauge and be arranged in a sensor housing with a pressure medium. The remaining structure of such a pressure gauge can be found, for example, in DE 10 2007 053 859 A1, in particular in Fig. 2. This design of a pressure gauge has been known for many years in the context of pressure measuring devices per se and is fully disclosed in many other documents of the patent holder.
[0104] Figures 3 and 4 show two further variants of a pressure measuring device according to the invention. The reference numerals for functionally identical components were adopted identically from Figure 1.
[0105] In Fig. 3, the projections 23 on the underside of the base 3 are omitted. This allows for better decoupling to the radial outside when the base 3 is inserted into the recess 27 of the support 2. However, at the same time the support surface of the base 3 relative to the support 2 is reduced, and a double seal by means of a two-part joining surface 20 is omitted in favor of better thermal decoupling.
[0106] Fig. 4 then represents a compromise between Fig. 1 and Fig. 3. The projections 23 are offset closer to the central axis 100, while the radial dimensions of the base 3 remain the same. This creates an inner annular recess 21 and another outer annular recess beyond the projections 23 between the base 3 and the support 2. This results in improved thermal decoupling of the edge surfaces of the projections 23 from the support and simultaneously improved thermal decoupling in the area of sections 18a and 18b of the end face 18, while providing a dual sealing function through the joints on the projection 23 and the support extension 24.
[0107] Reference symbol list
[0108] 1 Pressure measuring device
[0109] 2 carriers
[0110] 3 sockets
[0111] 4 pressure sensor
[0112] 5 membrane carriers
[0113] 6 measuring membrane
[0114] 7 Pressure chamber
[0115] 8 Support area
[0116] 9 Pressure transmission line
[0117] 10 sensor elements
[0118] 11 Middle segment
[0119] 12 base
[0120] 13th continuation
[0121] 14. Providence
[0122] 15 Frontal surface (protrusion)
[0123] 16 Front surface (pressure sensor)
[0124] 17 Base area
[0125] 18 End face (base)
[0126] 18a Sub-area (projection)
[0127] 18b Sub-area (supporting process)
[0128] 19 End face (beam)
[0129] 20 Providence
[0130] 21 recess
[0131] 22 floor area
[0132] 23 lead
[0133] 24 Supporting process
[0134] 25 Internal fluid line
[0135] 26 Middle range
[0136] 27 Exclusion
[0137] 100 Center axis
[0138] 101 First Step - Preparing and Contouring (Base)
[0139] 102 Second step - Provision and contouring (measuring membrane)
[0140] 103 Third step - Preparation and contouring (membrane carrier)
[0141] 104 fourth step - stacking
[0142] 105 fifth step - separating
[0143] 106 sixth step - joining process
Claims
Patent claims 1. Pressure measuring device (1) comprising a support (2), in particular a metallic support (2), a base (3) connected to the support (2), and a pressure sensor (4) mounted on a free-standing end of the base (3), wherein the pressure measuring device (1) has a central axis (100), wherein the base (3) has an end face (18) facing the support (2), which is connected by means of a joint (20) to an end face (19) of the support (2) facing the base (3), characterized in that an annular recess (21) is provided on the side of the base (3) facing the support (2) between the support (2) and the base (3), which is bounded radially inwards by a support extension (24) and which has a bottom surface (22) that extends substantially on a plane perpendicular to the central axis (100), wherein the end face (18) is at least partially enclosed by the support extension (24) is provided.
2. Pressure measuring device according to claim 1, characterized in that the annular recess (21) is arranged in the base (3) and is provided open towards the support (2), which is limited radially outwards from the central axis (100) by a projection (23) of the base, wherein the end face (18) of the base (3) facing the support (2) is divided into at least two spatially separated sub-areas (18a, 18b), wherein a first sub-area (18a) is provided by the projection (23) and a second sub-area (18b) by the support extension (24).
3. Pressure measuring device according to claim 1 or 2, characterized in that the outer contours of a base (12) of the socket (3) and of the pressure sensor (4) have an identical radial distance to the central axis (100).
4. Pressure measuring device according to one of the preceding claims, characterized in that the projection (23) and the annular recess (21) are designed as a square ring shape.
5. Pressure measuring device according to one of the preceding claims, characterized in that the support extension (24) is designed as a pipe extension, wherein the pipe extension has an internal fluid line (25) which is designed as a section of the pressure transmission line (9) which extends from a pressure chamber (7) in the pressure sensor (4) through the base (3) and through the support (2).
6. Pressure measuring device according to one of the preceding claims, characterized in that the pressure sensor (4) is essentially made of silicon and that the carrier (2) is made of stainless steel, wherein the base (3) is made of glass, preferably borosilicate glass, preferably with a borosilicate content of more than 50 wt.%.
7. Pressure measuring device according to one of the preceding claims, characterized in that the pressure transmission line (9) has a uniform diameter over its course from the carrier (2) to the pressure chamber (7).
8. Pressure measuring device according to one of the preceding claims, characterized in that at least one of the partial areas (18a) and / or (18b) of the end face (18) has a minimum width of less than 0.7 mm, preferably between 0.3 - 0.5 mm.
9. Pressure measuring device according to one of the preceding claims, characterized in that the material thickness (H) in the area of the projection (23) is at least 0.6 mm and that the depth tolerance in the area of the base surface (22) is particularly preferably less than + / - 150 pm.
10. Pressure measuring device according to one of the preceding claims, characterized in that the recess (21) is formed by laser profiling with a positional accuracy of less than 30 pm, preferably 10-25 pm.
11. Pressure measuring device according to one of the preceding claims, characterized in that the base surface extends radially from the central axis (100) over at least 5%, preferably at least 10%, particularly preferably between 30-90% of the maximum radial extent of the base (3).
12. Method for manufacturing a pressure measuring device, preferably a pressure measuring device (1) according to one of the preceding claims, comprising a silicon-based semiconductor pressure sensor (4) with a measuring diaphragm (6) and a diaphragm support (5), a metallic support (2) and a base (3) made of glass, which is arranged in a stack for electrical insulation between the pressure sensor (4) and the support (2), wherein the method is characterized by the following steps: A. Providing and contouring a first and / or a second silicon plate, forming the end faces of a measuring membrane (6) and a membrane support (5) facing each other in the stacking direction to form a pressure chamber (7), wherein the contouring is carried out by a laser ablation process; and Providing and contouring a glass plate, forming a surface that is compatible with the support (2) and an end face (15, 18) of the base facing the pressure sensor (4) (3); B Stacking and joining the first silicon plate, the second silicon plate and the glass plate to form a plate stack with at least one joining point (14) of the pressure measuring device (1); C. Singling out a pressure sensor base assembly from the stack of plates and D. Material-bonded fixing of an end face (18) of a glass base (3) of the pressure sensor base assembly to the carrier (2) forming the pressure measuring device (1).
13. Method according to claim 10, characterized in that one or all Silicon plates and / or the glass plate have positioning aids, such as openings, outside of a surface contoured area.
14. Method according to one of the preceding claims, characterized in that singulation in step C is carried out by sawing the superimposed plates of the Stacks featuring a plurality of isolated pressure sensor base assemblies.