WO2009003826A1 - Pressure sensor - Google Patents

Pressure sensor Download PDF

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Publication number
WO2009003826A1
WO2009003826A1 PCT/EP2008/057490 EP2008057490W WO2009003826A1 WO 2009003826 A1 WO2009003826 A1 WO 2009003826A1 EP 2008057490 W EP2008057490 W EP 2008057490W WO 2009003826 A1 WO2009003826 A1 WO 2009003826A1
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WO
WIPO (PCT)
Prior art keywords
pressure sensor
pressure
sensor according
joint
measuring
Prior art date
Application number
PCT/EP2008/057490
Other languages
German (de)
French (fr)
Inventor
Ulfert Drewes
Frank Hegner
Andreas Rossberg
Elke Schmidt
Original Assignee
Endress+Hauser Gmbh+Co.Kg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Endress+Hauser Gmbh+Co.Kg filed Critical Endress+Hauser Gmbh+Co.Kg
Publication of WO2009003826A1 publication Critical patent/WO2009003826A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
    • G01L9/0072—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance
    • G01L9/0075—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance using a ceramic diaphragm, e.g. alumina, fused quartz, glass
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/0061—Electrical connection means
    • G01L19/0084—Electrical connection means to the outside of the housing

Definitions

  • the present invention relates to a pressure sensor, in particular a pressure sensor with a ceramic base body and a ceramic measuring membrane.
  • Pressure sensors in the sense used here include absolute pressure sensors and relative pressure sensors, which measure the absolute pressure of a medium against vacuum or the difference between the pressure in a medium and the current atmospheric pressure. Furthermore, the pressure sensors according to the invention comprise differential pressure sensors, which detect the pressure difference between a first and second media pressure.
  • a generic pressure sensor comprises a base body and at least one measuring diaphragm which is pressure-tightly connected to the main body by means of an active brazing to form a measuring chamber, and a transducer for converting a pressure-dependent deformation of the measuring diaphragm into an electrical primary signal, and a primary signal path extending itself extends through the body.
  • the converter may be, for example, a capacitive or a resistive converter.
  • the primary signal path usually comprises at least one electrical feedthrough through the main body.
  • Such pressure sensors are manufactured by the applicant under the name Cerabar and placed on the market.
  • Implementation may be, for example, a metal pin which extends through the base body, wherein an annular gap between the metal pin and the ceramic material is sealed by means of an active solder.
  • an active solder is used, which is compatible with a subsequent soldering process.
  • an Ag-Cu active solder is suitable.
  • such an active solder has a melting point that is more than 100K lower than the preferred active hard solder for joining the measuring membrane to the ceramic body.
  • the components of the active solder may evaporate to different extents due to their different vapor pressure values, whereby on the one hand the composition of the active solder can adversely change, and on the other hand a contamination of the active brazing material or the surfaces to be soldered can take place ,
  • the pressure sensor comprises a base body and at least one measuring diaphragm, which is pressure-tightly connected to form a measuring chamber with the base body by means of a first joint, which has an active brazing, and a transducer for converting a pressure-dependent deformation of the measuring diaphragm into a primary electrical signal, and a primary signal path; extending from the transducer through the body, the primary signal path comprising at least one electrical conductor passing through the body in a portion through an aperture, characterized in that the aperture is closed by a metallic body having a substantially planar surface has, which faces the measuring chamber, and which is joined by means of an opening enclosing the second joint by means of an active brazing pressure-tight with the body, wherein the active braze of the second joint has a melting point of not more than 50 ° C, preferably not more than 25 ° C lower than that of the Aktivhartlots the first joint.
  • the base body and / or the measuring membrane preferably have a ceramic material, in particular corundum.
  • the second joint on the same active brazing on the first joint.
  • ternary active hard solders which have a Zr / Ni alloy and Ti and are described in EP 0 490 807 B1.
  • the metallic body has a surface facing away from the measuring chamber, which is contactable by means of a soft solder.
  • the surface of the metallic body facing away from the measuring chamber may optionally have a metallic coating, for example a Ni layer, which may be gold plated for protection against oxidation.
  • the metallic coating or the Ni layer has, for example, a thickness of not less than 0.5 ⁇ m, preferably not less than 1 ⁇ m.
  • the layer thickness is about 2 microns.
  • the gold layer may have some 10 nm, for example 20 nm.
  • the metal body may comprise, for example, tungsten or an alloy containing molybdenum and copper or molybdenum, titanium and zirconium.
  • tungsten or an alloy containing molybdenum and copper or molybdenum, titanium and zirconium.
  • the thermal expansion coefficient matches that of the main body material or active brazing material, whereby a complete correspondence of the thermal expansion coefficients is not absolutely necessary. It is sufficient if the different thermal expansion does not lead to failure of the solder joint.
  • a Mo-Ti-Zr alloy available under the name TZM from Goodfellow and Plansee.
  • the metal body may be formed, for example, circular disk-shaped, and are inserted into a matching recess in a surface of the base body, wherein the opening opens into the recess.
  • the electrical conductor can be for example a metal pin, in particular a Ta pin, which extends from the transducer through the opening to the second joint.
  • the electrical conductor comprises a coating of the opening wall containing glass and at least one noble metal element. Notwithstanding the Choice of material of the electrical conductor is to ensure sufficient contact with the second joint, since the primary signal path extends over the second joint and the metallic body.
  • a line is connected to a circuit for signal preprocessing by means of a soft solder connection.
  • FIG. 1 shows a longitudinal section through a pressure sensor according to the invention.
  • the pressure sensor 1 shown in Fig. 1 comprises a cylindrical
  • Base body 2 and a circular disk-shaped measuring diaphragm 3, both having corundum as a material.
  • the main body 2 and the measuring diaphragm 3 are pressure-tightly joined together by means of a circumferential joint 4, wherein the gap between the measuring diaphragm and the base body is defined by the joint 4, which comprises an active brazing material.
  • a measuring chamber is formed, in which, depending on the objective of the pressure sensor, a different back pressure prevails to a force acting on the outside of the measuring diaphragm pressure.
  • the back pressure is the atmospheric pressure in the vicinity of the sensor, which is introduced into the measuring chamber via a channel, not shown here.
  • the back pressure should be negligible, the measuring chamber is evacuated accordingly.
  • the pressure sensor 1 comprises a capacitive transducer.
  • the capacitive transducer comprises a measuring electrode 5 on the measuring chamber side surface of the measuring membrane 3, which is contacted via the joint 4, and at least one counter electrode 6 on the measuring chamber side end face of the base body 2, which is contacted via an electrical conductor which extends through an opening 7 by the Measuring chamber extends substantially in the axial direction through the base body 2.
  • the electrical conductor comprises a conductive layer containing glass and at least one noble metal element, for example gold and / or platinum.
  • the layer material has been introduced as a paste in the opening 7 and baked in.
  • the measuring electrode and the counter electrode may have substantially the same material as the electrical conductor.
  • the opening 7 is closed with a means of a Aktivhartlotplättchens 8, circular disc-shaped metal plate 9, which has a thickness of about 200 microns and a diameter of about 4 mm.
  • the metal plate 9 comprises a Mo-Ti-Zr alloy.
  • a recess 10 is provided in the rear end face 11 of the base body 2, in which the opening 7 opens.
  • the metal plate 9 has as Weichlot. anyway on his
  • the pressure sensor according to the invention allows a simplified production, since the joints between the measuring membrane and the base body on the one hand and between the metal body to close the opening for the primary signal path and the main body on the other hand have similar or identical material properties. Furthermore, the pressure sensor according to the invention allows improved contacting of the primary signal path.

Abstract

A pressure sensor (1) comprises a basic body (2); and a measuring diaphragm (3) which is connected to the basic body (2) in a pressure-tight manner by means of a first joining point (4), which has an active brazing solder, so as to form a measuring chamber; and a converter (5, 6) for converting a pressure-dependent deformation of the measuring diaphragm into a primary electrical signal; and a primary signal path which extends from the converter through the basic body, wherein the primary signal path comprises at least one electrical conductor which runs in a section through an opening (7) through the basic body; wherein the opening is closed using a metal body (9) having a planar surface which faces the measuring chamber and is joined to the basic body (2) in a pressure-tight manner by means of a second joining point (8) which surrounds the opening (7) and has an active brazing solder, wherein the active brazing solder of the second joining point (8) has a melting point which is no more than 50°C or 25°C lower than that of the active brazing solder of the first joining point.

Description

Beschreibung description
Drucksensorpressure sensor
[0001] Die vorliegende Erfindung betrifft einen Drucksensor, insbesondere einen Drucksensor mit einem keramischen Grundkörper und einer keramischen Messmembran.The present invention relates to a pressure sensor, in particular a pressure sensor with a ceramic base body and a ceramic measuring membrane.
[0002] Drucksensoren im hier verwendeten Sinn umfassen Absolutdrucksensoren und Relativdrucksensoren, welche den absoluten Druck eines Messmediums gegen Vakuum bzw. die Differenz zwischen dem Druck in einem Messmedium und dem aktuellen Atmosphärendruck messen. Weiterhin umfassen die Drucksensoren im Sinne der Erfindung Differenzdrucksensoren, welche die Druckdifferenz zwischen einem ersten und zweiten Mediendruck erfassen.Pressure sensors in the sense used here include absolute pressure sensors and relative pressure sensors, which measure the absolute pressure of a medium against vacuum or the difference between the pressure in a medium and the current atmospheric pressure. Furthermore, the pressure sensors according to the invention comprise differential pressure sensors, which detect the pressure difference between a first and second media pressure.
[0003] Ein gattungsgemäßer Drucksensor umfasst einen Grundkörper und mindestens eine Messmembran, die unter Bildung einer Messkammer mit dem Grundkörper mittels eines Aktivhartlots druckdicht verbunden ist, und einen Wandler zum Wandeln einer druckabhängigen Verformung der Messmembran in ein elektrisches Primärsignal, sowie einen Primärsignalpfad, der sich durch den Grundkörper erstreckt. Der Wandler kann beispielsweise ein kapazitiver oder ein resistiver Wandler sein. Der Primärsignalpfad umfasst gewöhnlich mindestens eine elektrische Durchführung durch den Grundkörper.A generic pressure sensor comprises a base body and at least one measuring diaphragm which is pressure-tightly connected to the main body by means of an active brazing to form a measuring chamber, and a transducer for converting a pressure-dependent deformation of the measuring diaphragm into an electrical primary signal, and a primary signal path extending itself extends through the body. The converter may be, for example, a capacitive or a resistive converter. The primary signal path usually comprises at least one electrical feedthrough through the main body.
[0004] Derartige Drucksensoren werden von der Anmelderin unter der Bezeichnung Cerabar hergestellt und in Verkehr gebracht.Such pressure sensors are manufactured by the applicant under the name Cerabar and placed on the market.
[0005] Bei Drucksensoren mit keramischen Grundkörpern kann dieseIn pressure sensors with ceramic bodies this can
Durchführung beispielsweise ein Metallstift sein, der sich durch den Grundkörper erstreckt, wobei ein Ringspalt zwischen dem Metallstift und dem keramische Material mittels eines Aktivlots abgedichtet ist. Um die Kontaktierung der elektrischen Durchführung mittels einer Weichlotverbindung zu ermöglichen, wird ein Aktivlot eingesetzt, welches mit einem anschließenden Weichlotprozess kompatibel ist. Hierzu ist beispielsweise ein Ag-Cu-Aktivlot geeignet. Ein derartiges Aktivlot weist jedoch einen um mehr als 100K niedrigeren Schmelzpunkt auf, als die bevorzugten Aktivhartlote zum Fügen der Messmembran mit dem keramischen Grundkörper. Insoweit können in einem Hochvakuumlötprozess bis zum Erreichen der Schmelztemperatur des Aktivhartlots die Komponenten des Aktivlots aufgrund ihrer unterschiedlichen Dampfdruckwerte unterschiedlich stark abdampfen, wodurch einerseits die Zusammensetzung des Aktivlots sich nachteilig verändern kann, und andererseits eine Kontamination des Aktivhartlots bzw. der damit zu lötenden Oberflächen erfolgen kann.Implementation may be, for example, a metal pin which extends through the base body, wherein an annular gap between the metal pin and the ceramic material is sealed by means of an active solder. In order to enable the contacting of the electrical feedthrough by means of a soft solder connection, an active solder is used, which is compatible with a subsequent soldering process. For this purpose, for example, an Ag-Cu active solder is suitable. However, such an active solder has a melting point that is more than 100K lower than the preferred active hard solder for joining the measuring membrane to the ceramic body. In that regard, in a high vacuum soldering process, the components of the active solder may evaporate to different extents due to their different vapor pressure values, whereby on the one hand the composition of the active solder can adversely change, and on the other hand a contamination of the active brazing material or the surfaces to be soldered can take place ,
[0006] Es bleibt daher nur ein enges Fenster von Prozessparametern, bei denen die Herstellung der beschriebenen Drucksensoren im Hochvakuumlötprozess überhaupt erfolgen kann. Es ist daher die Aufgabe der Erfindung, einen gattungsgemäßen Drucksensor bereitzustellen, der einem robusteren Fertigungsverfahren zugänglich ist.Therefore, it remains only a narrow window of process parameters, in which the production of the pressure sensors described can be done in Hochvakuumlötprozess at all. It is therefore the object of the invention to provide a generic pressure sensor which is accessible to a more robust manufacturing process.
[0007] Die Aufgabe wird gelöst durch den Drucksensor gemäß des unabhängigen Patentanspruchs 1.The object is achieved by the pressure sensor according to the independent claim 1.
[0008] Der erfindungsgemäße Drucksensor umfasst einen Grundkörper und mindestens eine Messmembran, die unter Bildung einer Messkammer mit dem Grundkörper mittels einer ersten Fügestelle, die ein Aktivhartlot aufweist druckdicht verbunden ist, und einen Wandler zum Wandeln einer druckabhängigen Verformung der Messmembran in ein elektrisches Primärsignal, sowie einen Primärsignalpfad; der sich von dem Wandler durch den Grundkörper erstreckt, wobei der Primärsignalpfad mindestens einen elektrischen Leiter umfasst, der in einem Abschnitt durch eine Öffnung durch den Grundkörper verläuft, dadurch gekennzeichnet, dass die Öffnung mittels eines metallischen Körpers verschlossen ist, der eine im wesentlichen ebene Fläche aufweist, die der Messkammer zugewandt ist, und die mittels einer die Öffnung umschließenden zweiten Fügestelle mittels eines Aktivhartlots druckdicht mit dem Grundkörper gefügt ist, wobei das Aktivhartlot der zweiten Fügestelle einen Schmelzpunkt aufweist, der nicht mehr als 50°C, vorzugsweise nicht mehr als 25°C niedriger ist als jener des Aktivhartlots der ersten Fügestelle.The pressure sensor according to the invention comprises a base body and at least one measuring diaphragm, which is pressure-tightly connected to form a measuring chamber with the base body by means of a first joint, which has an active brazing, and a transducer for converting a pressure-dependent deformation of the measuring diaphragm into a primary electrical signal, and a primary signal path; extending from the transducer through the body, the primary signal path comprising at least one electrical conductor passing through the body in a portion through an aperture, characterized in that the aperture is closed by a metallic body having a substantially planar surface has, which faces the measuring chamber, and which is joined by means of an opening enclosing the second joint by means of an active brazing pressure-tight with the body, wherein the active braze of the second joint has a melting point of not more than 50 ° C, preferably not more than 25 ° C lower than that of the Aktivhartlots the first joint.
[0009] Der Grundkörper und/oder die Messmembran weisen vorzugsweise einen keramischen Werkstoff auf, insbesondere Korund.The base body and / or the measuring membrane preferably have a ceramic material, in particular corundum.
[0010] Vorzugsweise weist die zweite Fügestelle das gleiche Aktivhartlot auf wie die erste Fügestelle. Derzeit bevorzugt sind ternäre Aktivhartlote, die eine Zr/Ni-Legierung und Ti aufweisen und in EP 0 490 807 B1 beschrieben sind.Preferably, the second joint on the same active brazing on the first joint. Presently preferred are ternary active hard solders which have a Zr / Ni alloy and Ti and are described in EP 0 490 807 B1.
[0011] In einer Weiterbildung der Erfindung weist der metallische Körper eine der Messkammer abgewandte Oberfläche auf, die mittels eines Weichlots kontaktierbar ist. Hierzu kann die der Messkammer abgewandte Oberfläche des metallischen Körpers ggf. eine metallische Beschichtung aufweisen, beispielsweise eine Ni-Schicht, die zum Schutz vor Oxidation vergoldet sein kann. Die metallische Beschichtung bzw. die Ni-Schicht weist beispielsweise eine Stärke von nicht weniger als 0,5 μm, bevorzugt nicht weniger als 1 μm auf.In one embodiment of the invention, the metallic body has a surface facing away from the measuring chamber, which is contactable by means of a soft solder. For this purpose, the surface of the metallic body facing away from the measuring chamber may optionally have a metallic coating, for example a Ni layer, which may be gold plated for protection against oxidation. The metallic coating or the Ni layer has, for example, a thickness of not less than 0.5 μm, preferably not less than 1 μm.
[0012] In einer derzeit bevorzugten Ausgestaltung beträgt die Schichtstärke etwa 2 μm. Die Goldschicht kann einige 10 nm aufweisen, beispielsweise 20 nm.In a presently preferred embodiment, the layer thickness is about 2 microns. The gold layer may have some 10 nm, for example 20 nm.
[0013] Der Metallkörper kann beispielsweise Wolfram oder eine Legierung aufweisen, die Molybdän und Kupfer bzw. Molybdän, Titan und Zirkonium enthält. Bei der Materialwahl ist darauf zu achten, dass der Wärmeausdehnungskoeffizient zu dem des Grundkörpermaterials bzw. des Aktivhartlots passt, wobei eine vollständige Übereinstimmung der Wärmeausdehnungskoeffizienten nicht zwingend erforderlich ist. Es reicht aus, wenn die unterschiedliche Wärmeausdehnung nicht zum Versagen der Lötstelle führt. Derzeit bevorzugt ist eine Mo-Ti-Zr-Legierung, die unter der Bezeichnung TZM von den Firmen Goodfellow und Plansee erhältlich ist.The metal body may comprise, for example, tungsten or an alloy containing molybdenum and copper or molybdenum, titanium and zirconium. When choosing the material, it must be ensured that the thermal expansion coefficient matches that of the main body material or active brazing material, whereby a complete correspondence of the thermal expansion coefficients is not absolutely necessary. It is sufficient if the different thermal expansion does not lead to failure of the solder joint. Presently preferred is a Mo-Ti-Zr alloy available under the name TZM from Goodfellow and Plansee.
[0014] Der Metallkörper kann beispielsweise kreisscheibenförmig ausgebildet sein, und in eine passende Aussparung in einer Oberfläche des Grundkörpers eingelegt werden, wobei die Öffnung in der Aussparung mündet.The metal body may be formed, for example, circular disk-shaped, and are inserted into a matching recess in a surface of the base body, wherein the opening opens into the recess.
[0015] Der elektrische Leiter kann beispielsweise ein Metallstift sein, insbesondere ein Ta-Stift, der sich von dem Wandler durch die Öffnung bis zu der zweiten Fügestelle erstreckt. In einer anderen Ausgestaltung umfasst der elektrische Leiter eine Beschichtung der Öffnungswand, die Glas und mindestens ein Edelmetallelement enthält. Ungeachtet der Materialwahl des elektrischen Leiters ist eine ausreichende Kontaktierung der zweiten Fügestelle zu gewährleisten, da der Primärsignalpfad über die zweite Fügestelle und den metallischen Körper verläuft.The electrical conductor can be for example a metal pin, in particular a Ta pin, which extends from the transducer through the opening to the second joint. In another embodiment, the electrical conductor comprises a coating of the opening wall containing glass and at least one noble metal element. Notwithstanding the Choice of material of the electrical conductor is to ensure sufficient contact with the second joint, since the primary signal path extends over the second joint and the metallic body.
[0016] Auf der dem Wandler abgewandten Oberfläche des metallischen Körpers kann der Primärsignalpfad fortgesetzt werden, indem beispielsweise eine Leitung zu einer Schaltung zur Signalvorverarbeitung mittels einer Weichlotverbindung angeschlossen wird.On the side facing away from the transducer surface of the metallic body of the primary signal path can be continued by, for example, a line is connected to a circuit for signal preprocessing by means of a soft solder connection.
[0017] Die Erfindung wird nun anhand eines in der Zeichnung dargestellten Ausführungsbeispiels erläutert.The invention will now be explained with reference to an embodiment shown in the drawing.
Es zeigt: Fig. 1 : einen Längsschnitt durch einen erfindungsgemäßen Drucksensor.1 shows a longitudinal section through a pressure sensor according to the invention.
[0018] Der in Fig. 1 dargestellte Drucksensor 1 umfasst einen zylindrischenThe pressure sensor 1 shown in Fig. 1 comprises a cylindrical
Grundkörper 2, und eine kreisscheibenförmige Messmembran 3, wobei beide Korund als Werkstoff aufweisen. Der Grundkörper 2 und die Messmembran 3 sind mittels einer umlaufenden Fügestelle 4 druckdicht miteinander gefügt, wobei durch die Fügestelle 4, die ein Aktivhartlot umfasst, der Abstand zwischen der Messmembran und dem Grundkörper definiert ist.Base body 2, and a circular disk-shaped measuring diaphragm 3, both having corundum as a material. The main body 2 and the measuring diaphragm 3 are pressure-tightly joined together by means of a circumferential joint 4, wherein the gap between the measuring diaphragm and the base body is defined by the joint 4, which comprises an active brazing material.
[0019] Zwischen der Messmembran 3 und dem Grundkörper 2 ist eine Messkammer ausgebildet, in welcher je nach Zielsetzung des Drucksensors ein anderer Gegendruck zu einem auf die Außenseite der Messmembran einwirkenden Druck vorherrscht. Bei einem Relativdrucksensor ist der Gegendruck der Atmosphärendruck in der Umgebung des Sensors, der über einen hier nicht dargestellten Kanal in die Messkammer eingeleitet wird. Bei einem Absolutdrucksensor soll der Gegendruck vernachlässigbar gering sein, die Messkammer ist dementsprechend evakuiert.Between the measuring diaphragm 3 and the base body 2, a measuring chamber is formed, in which, depending on the objective of the pressure sensor, a different back pressure prevails to a force acting on the outside of the measuring diaphragm pressure. In a relative pressure sensor, the back pressure is the atmospheric pressure in the vicinity of the sensor, which is introduced into the measuring chamber via a channel, not shown here. In an absolute pressure sensor, the back pressure should be negligible, the measuring chamber is evacuated accordingly.
[0020] Der Drucksensor 1 umfasst einen kapazitiven Wandler. Der kapazitive Wandler umfasst eine Messelektrode 5 auf messkammerseitigen Oberfläche der Messmembran 3, die über die Fügestelle 4 kontaktiert ist, und mindestens eine Gegenelektrode 6 auf der messkammerseitigen Stirnfläche des Grundkörpers 2, die über einen elektrischen Leiter kontaktiert ist, der sich durch eine Öffnung 7 erstreckt, die von der Messkammer im wesentlichen in axialer Richtung durch den Grundkörper 2 verläuft.The pressure sensor 1 comprises a capacitive transducer. The capacitive transducer comprises a measuring electrode 5 on the measuring chamber side surface of the measuring membrane 3, which is contacted via the joint 4, and at least one counter electrode 6 on the measuring chamber side end face of the base body 2, which is contacted via an electrical conductor which extends through an opening 7 by the Measuring chamber extends substantially in the axial direction through the base body 2.
[0021] Der elektrische Leiter umfasst eine leitfähige Schicht, die Glas und mindestens ein Edelmetallelement enthält, beispielsweise Gold und/oder Platin. Das Schichtmaterial ist als Paste in die Öffnung 7 eingebracht und in eingebrannt worden. Die Messelektrode und die Gegenelektrode können im Wesentlichen das gleiche Material wie der elektrische Leiter aufweisen.The electrical conductor comprises a conductive layer containing glass and at least one noble metal element, for example gold and / or platinum. The layer material has been introduced as a paste in the opening 7 and baked in. The measuring electrode and the counter electrode may have substantially the same material as the electrical conductor.
[0022] Die Öffnung 7 ist mit einem mittels eines Aktivhartlotplättchens 8 gefügten, kreisscheibenförmigen Metallplättchen 9 verschlossen, welches eine Stärke von etwa 200 μm und einem Durchmesser von etwa 4 mm aufweist. Das Metallplättchen 9 umfasst eine Mo-Ti-Zr-Legierung.The opening 7 is closed with a means of a Aktivhartlotplättchens 8, circular disc-shaped metal plate 9, which has a thickness of about 200 microns and a diameter of about 4 mm. The metal plate 9 comprises a Mo-Ti-Zr alloy.
[0023] Um die Positionierung des Aktivhartlotrings 8, und des Metallplättchens 9 zu erleichtern, ist in der rückseitigen Stirnfläche 11 des Grundkörpers 2 eine Aussparung 10 vorgesehen, in welcher die Öffnung 7 mündet.In order to facilitate the positioning of the active brazing ring 8, and the metal plate 9, a recess 10 is provided in the rear end face 11 of the base body 2, in which the opening 7 opens.
[0024] Das Metallplättchen 9 weist als Weichlotkontaktpunkt auf seiner derThe metal plate 9 has as Weichlotkontaktpunkt on his
Öffnung 7 abgewandten Oberfläche eine 2 μm starke Ni-Schicht auf, die mit einer 10 nm starken Au-Schicht gegen Oxidation geschützt ist. Vor dem Aufbringen der Ni-Schicht wurde die Oberfläche mittels Plasmaätzen vorbehandelt. An den solchermaßen präparierten Weichlotkontaktpunkt, können weitere Schaltungen zur Aufbereitung des Primärsignals angeschlossen werden, wobei die Herstellung der Weichlotkontakte auch in automatisierten Verfahren erfolgen kann. Unter Schutzgas kann hierbei ggf. auf Flussmittel verzichtet werden.7 opening facing away from a 2 micron thick Ni layer, which is protected with a 10 nm thick Au layer against oxidation. Before applying the Ni layer, the surface was pretreated by plasma etching. At the thus prepared soft solder contact point, further circuits for the preparation of the primary signal can be connected, wherein the production of soft solder contacts can also be done in automated processes. Under protective gas can be dispensed with flux here if necessary.
[0025] Im Ergebnis erlaubt der erfindungsgemäße Drucksensor eine vereinfachte Herstellung, da die Fügestellen zwischen der Messmembran und dem Grundkörper einerseits sowie zwischen dem Metallkörper zum Verschluss der Öffnung für den Primärsignalpfad und dem Grundkörper andererseits ähnliche bzw. identische Materialeigenschaften aufweisen. Weiterhin erlaubt der erfindungsgemäße Drucksensor eine verbesserte Kontaktierung des Primärsignalpfads. As a result, the pressure sensor according to the invention allows a simplified production, since the joints between the measuring membrane and the base body on the one hand and between the metal body to close the opening for the primary signal path and the main body on the other hand have similar or identical material properties. Furthermore, the pressure sensor according to the invention allows improved contacting of the primary signal path.

Claims

Ansprüche claims
1. 1. Drucksensor (1), umfassend: einen Grundkörper (2); und eine Messmembran (3), die unter Bildung einer Messkammer mit dem Grundkörper (2) mittels einer ersten Fügestelle (4) die ein Aktivhartlot aufweist, druckdicht verbunden ist; und einen Wandler (5, 6) zum Wandeln einer druckabhängigen Verformung der Messmembran in ein elektrisches Primärsignal; sowie einen Primärsignalpfad, der sich von dem Wandler durch den Grundkörper erstreckt, wobei der Primärsignalpfad mindestens einen elektrischen Leiter umfasst, der in einem Abschnitt durch eine Öffnung (7) durch den Grundkörper verläuft; dadurch gekennzeichnet, dass die Öffnung mittels eines metallischen Körpers (9) verschlossen ist, der eine im wesentlichen ebene Fläche aufweist, die der Messkammer zugewandt ist, und die mittels einer die Öffnung (7) umschließenden zweiten Fügestelle (8), die ein Aktivhartlot aufweist, druckdicht mit dem Grundkörper (2) gefügt ist, wobei das Aktivhartlot der zweiten Fügestelle (8) einen Schmelzpunkt aufweist, der nicht mehr als 50°C, vorzugsweise nicht mehr als 25°C niedriger ist als jener des Aktivhartlots der ersten Fügestelle (4).A first pressure sensor (1) comprising: a body (2); and a measuring diaphragm (3) which is pressure-tightly connected to the base body (2) by forming a measuring chamber by means of a first joint (4) having an active brazing solder; and a transducer (5, 6) for converting a pressure-dependent deformation of the measuring diaphragm into a primary electrical signal; and a primary signal path extending from the transducer through the body, the primary signal path including at least one electrical conductor extending in a portion through an aperture (7) through the body; characterized in that the opening is closed by means of a metallic body (9) having a substantially planar surface facing the measuring chamber and by means of a second joint (8) enclosing the opening (7) and having an active brazing solder , pressure-tight with the base body (2) is joined, wherein the active brazing material of the second joint (8) has a melting point which is not more than 50 ° C, preferably not more than 25 ° C lower than that of the active braze of the first joint (4 ).
2. 2. Drucksensor nach Anspruch 1 , wobei der Grundkörper und/oder die Messmembran einen keramischen Werkstoff aufweisen, insbesondere Korund.2. Pressure sensor according to claim 1, wherein the base body and / or the measuring membrane comprise a ceramic material, in particular corundum.
3. 3. Drucksensor nach Anspruch 1 oder 2, wobei die erste und die zweite Fügestelle das gleiche Aktivhartlot aufweisen.3. 3. Pressure sensor according to claim 1 or 2, wherein the first and the second joint have the same active hard solder.
4. 4. Drucksensor nach einem der Ansprüche 1 bis 3, wobei der metallische Körper (9) eine der Messkammer abgewandte Oberfläche aufweist, die mittels eines Weichlots kontaktierbar ist.4. Pressure sensor according to one of claims 1 to 3, wherein the metallic body (9) has a measuring chamber facing away from the surface, which is contacted by means of a soft solder.
5. 5. Drucksensor nach einem der Ansprüche 1 bis 4, wobei die der Messkammer abgewandte Oberfläche des metallischen Körpers (9) eine Ni-Schicht aufweist.5. 5. Pressure sensor according to one of claims 1 to 4, wherein the measuring chamber facing away from the surface of the metallic body (9) has a Ni layer.
6. 6. Drucksensor nach Anspruch 5, wobei die Ni-Schicht zum Schutz vor Oxidation vergoldet ist.6. 6. Pressure sensor according to claim 5, wherein the Ni layer is gold-plated for protection against oxidation.
7. 7. Drucksensor nach einem der vorhergehenden Ansprüche, wobei der Metallkörper (9) eine Legierung aufweist, die Molybdän und Kupfer bzw. Molybdän, Titan und Zirkonium enthält.7. A pressure sensor according to any one of the preceding claims, wherein the metal body (9) comprises an alloy containing molybdenum and copper or molybdenum, titanium and zirconium.
8. 8. Drucksensor nach einem der vorhergehenden Ansprüche, wobei der elektrische Leiter einen Metallstift umfasst.8. 8. Pressure sensor according to one of the preceding claims, wherein the electrical conductor comprises a metal pin.
9. 9. Drucksensor nach einem der Ansprüche 1 bis 7, wobei der elektrische Leiter eine Beschichtung der Wand der Öffnung (7) umfasst, die Glas und mindestens ein Edelmetallelement enthält. 9. Pressure sensor according to one of claims 1 to 7, wherein the electrical conductor comprises a coating of the wall of the opening (7) containing glass and at least one noble metal element.
PCT/EP2008/057490 2007-07-03 2008-06-13 Pressure sensor WO2009003826A1 (en)

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