DE102018108744A1 - Method for producing a pressure sensor - Google Patents

Abstract

It is a method for producing a pressure sensor, the at least one by means of at least one joint (9) with at least one metallic body (7) connected ceramic body (5) described, with the comparatively simple and cost-effective manner, a comparatively high compressive strength and / or tightness of the respective joint (9) can be achieved, in which as the metallic body (7) a body is used which comprises an active component which can be used as an active component of an active brazing active ceramic brazing active component, generates an array comprising the ceramic body (5), the metallic body (7) and a brazing filler metal (13), wherein the brazing material (13) used is free from active brazing active components, and the assembly is heated to a bonding temperature the hard solder (13) is melted, a proportion of the active component contained in the metallic body (7) NEN through the with the metallic body (7) in contact and / or coming into contact, molten brazing material (13) diffuses through to the ceramic of the ceramic body (5) and there reacts with the ceramic such that one comprising the active component forms chemical compound.

Description

The invention relates to a method for producing a pressure sensor which comprises at least one ceramic body connected by means of at least one joint to at least one metallic body, and to a pressure sensor produced by means of this method.

Pressure sensors are used in industrial metrology for the metrological detection of pressures.

Among others, ceramic pressure sensors are used which comprise at least one ceramic body, e.g. a base body and / or a measuring membrane, including a pressure chamber connected to the base body. Depending on the design, these pressure sensors require one or more ceramic bodies of the pressure sensor to be connected to a metallic body by means of at least one joint. Depending on their position, these joints may, under certain circumstances, have to meet high demands on their pressure resistance and / or their tightness.

An example of this are feedthroughs, each of which comprises a pin-shaped, pressure-tight manner connected by a joint to the body through the body extending through metallic body, via which a connected thereto sensor component of the pressure sensor through the body through electrically contacted and / or to a Measuring electronics can be connected.

For example, in the DE 10 2008 043 567 A1 a pressure sensor is described which comprises a ceramic base body, and a connected under inclusion of a pressure chamber connected to the base body, which can be acted upon by a pressure to be detected by the pressure sensor metrology ceramic measuring membrane. This pressure sensor is equipped with a capacitive, electromechanical transducer which is designed such that it converts a pressure acting on the measuring membrane pressure acting deflection of the measuring diaphragm into an electrical variable. In addition, the pressure sensor comprises a passage extending through the main body, via which an electrode of a capacitor of the capacitive transducer is electrically connectable. The bushing comprises a metallic body connected to the electrode and designed as a tantalum pin, which is inserted into a bore extending through the main body and opening into the pressure chamber. The tantalum pin is the end connected by means of Aktivhartlötung with the ceramic body, which closes an existing between the base body and the tantalum pin inserted therein end.

Thus, the compressive strength and the tightness of the active brazing is largely determined by the pressure resistance and tightness of the implementation. Since the bore opens into the pressure chamber, a high compressive strength of the active brazing is esp. Required when the pressure chamber may be exposed to very high pressures in the measuring operation under certain circumstances. This is especially the case with differential pressure sensors, which have a measuring diaphragm arranged between two basic bodies and connected to each of the basic bodies in each case enclosing a pressure chamber. A high tightness is e.g. esp. Required when the pressure sensor is designed as an absolute pressure sensor whose pressure chamber is evacuated.

Active brazes are made by means of an active braze comprising an active component which reacts with the ceramic during active brazing. In this case, a reduction of the ceramic causes a mechanically high-strength chemical bond between the ceramic and the active brazing material.

Active hard solders offer the advantage of being able to wet ceramic components and allow direct brazing of ceramic components without prior metallization of the ceramic due to the active component contained therein.

The disadvantage, however, is that the active component makes controlled melting of the active brazing material difficult, active brazing alloys have comparatively poor flow properties and wetting of the ceramic and / or the reaction leading to the formation of the high-strength chemical compound can not be promoted by capillary effects. Among other things, this leads to the fact that active hard solders are only able to penetrate into comparatively narrow gaps to a limited extent.

This problem can be found in the DE 10 2009 003 178 A1 described manner be met by the fact that the tantalum pin before insertion into the bore in the ceramic body outside on all sides with a zirconium, nickel and titanium comprehensive active brazing is coated such that the coating at the border to the ceramic body has a higher titanium content than on the border to the metallic tantalum pin. This can be achieved, for example, by virtue of the fact that an outer layer of the coating adjacent to the ceramic of the basic body consists of titanium. According to the DE 10 2009 003 178 A1 is by increasing the proportion of the active component of titanium in the immediately adjacent to the outside bore surrounding lateral surface of the ceramic region of the Active brazing increases the reactivity to the ceramic material.

However, the coating of the tantalum pin with the active hard solder represents an additional, comparatively complicated method step, which increases the manufacturing costs of these pressure sensors.

It is an object of the invention to specify a method for producing a pressure sensor which comprises at least one ceramic body connected by means of at least one joint to at least one metallic body, with which in comparatively simple and cost-effective manner a comparatively high pressure resistance and / or tightness of the respective Can be achieved.

This object is achieved by a method for producing a pressure sensor which comprises at least one connected by means of at least one joint with at least one metallic body ceramic body, in which
a metallic body is used which comprises an active component which can be used as an active component of an active brazing agent suitable for active brazing of the ceramic body,
producing an assembly comprising the ceramic body, the metallic body and a braze, the braze being free of active brazing active components, and
heating the assembly to a bonding temperature at which the braze is fused, a portion of the active component contained in the metallic body is diffused through the molten brazing material in contact and / or in contact with the ceramic body of the ceramic body there reacts with the ceramic in such a way that forms a chemical compound comprising the active component.

The method according to the invention has the advantage that the active component diffuses through the molten brazing alloy to form the ceramic, where a highly pressure-resistant, high-density connection is then formed by the chemical reaction that occurs there. In particular, joints can thus be produced that include joint areas that extend over surface areas of the ceramic body that were initially not in direct contact with the active component in the arrangement.

Another advantage is that the melting of the brazing process can be much easier and better controlled than the melting of active hard soldering. In addition, the molten brazing alloy has significantly better flow properties compared to alternative active brazing materials. The latter is esp. Advantageous when sealed with the method comparatively narrow, located between the ceramic body and the metallic body column end, can not be introduced into the solder before the execution of the joining process or only with considerable effort.

A first development of the invention comprises a method in which
the metallic body consists of the active component or of a material comprising the active component,
the active component consists of titanium, zirconium, hafnium or vanadium,
the ceramic body consists of an oxide ceramic or alumina (Al ₂ O ₃ ), and / or
as brazing a silver-copper brazing, a silver-copper-indium brazing, a silver-copper-tin brazing or another brazing is used.

According to a second development, the joining process is carried out at a joining temperature which is greater than or equal to a melting temperature of the brazing alloy and which is lower than a melting temperature of an active brazing alloy comprising the components contained in the brazing alloy and the active component contained in the metallic body.

A third development of the invention comprises a method in which
the metallic body consists of titanium or a material comprising titanium,
the ceramic body consists of an oxide ceramic or aluminum oxide (Al ₂ O ₃ ),
as a brazing alloy a silver-copper brazing alloy a silver-copper-indium brazing alloy or a silver-copper-tin brazing alloy is used, and
the assembly is heated to a bonding temperature of less than or equal to 860 ° C or a bonding temperature in the range of 830 ° C to 860 ° C.

A fourth development comprises a method in which
the arrangement is made such that the brazing material is in direct contact with a surface region of the metallic body, that the brazing material is in direct contact with a surface region of the ceramic body, and that the brazing material has an end region between the two surface regions between the metallic body and the ceramic body located gap covers the end,
a portion of the active component contained in the metallic body is diffused through the molten brazing material in contact and / or in contact with the metallic body up to the surface area of the ceramic body, where a chemical compound is formed by reduction of the ceramic,
molten brazing material enters the gap, and
a portion of the active component contained in the metallic body through the metallic body in contact and / or coming into contact, molten brazing through to a gap outside on all sides surrounding and / or the gap limiting lateral surface of the ceramic body diffuses where then forms a chemical compound by reducing the ceramic.

A development of the fourth development comprises a method in which the resulting joint comprises a first joint region,
which extends over the surface areas of the metallic body and the surface area of the ceramic body,
which is arranged outside the gap and covers the gap at the end, and / or
whose edge region extending over the surface region of an end face of the ceramic body has a substantially annular disk-shaped base surface and / or has an edge width of greater than or equal to 0.4 mm and / or less than or equal to 1 mm.

A development of the fourth development or its development comprises a method in which the resulting joint comprises a second joint area,
which extends into the gap up to a gap height,
which surrounds an end region of the metallic body on all sides on the outside,
which essentially completely fills the gap over a gap height, and / or which substantially completely fills the gap over a gap height of greater than or equal to 0.2 mm and / or over a gap height of less than or equal to 1 mm,
wherein the gap height (h) corresponds in each case to a penetration depth up to which the molten brazing alloy, together with the active component diffusing therethrough, has penetrated into the gap during the joining process.

A fifth development of the invention comprises a method in which
the metallic body or at least one of the metallic bodies is in each case designed as a pin,
the respective pin is inserted into a bore extending through the ceramic body, and
an existing between the respective pin and the ceramic body gap is sealed by the joining of the respective pin to the ceramic body joining end.

A sixth development of the invention comprises a method in which, wherever molten brazing material is in direct contact with the metallic body and / or comes into direct contact with the metallic body, an alloy containing the components of the brazing alloy and the active component is formed, which is hereafter solidified to a portion of the joint.

Furthermore, the invention comprises a pressure sensor produced by the method according to the invention,
comprising a connected under inclusion of a pressure chamber connected to a base body, which can be acted upon by a pressure to be detected by the pressure sensor pressure to be measured diaphragm, and
comprising an electromechanical transducer, which is designed such that it converts a dependent of the measuring membrane pressure acting deflection of the measuring diaphragm into an electrical variable, which can be detected by means of a to be connected to the transducer or connected to the transducer measuring technology and / or and in a signal representing the pressure to be measured can be converted.

• a) einen zwischen dem Stift und dem keramischen Körper bestehenden Spalt endseitig abdichtet,
• b) derart ausgebildet ist, dass sie eine Abdichtung eines zwischen dem Stift und dem keramischen Körper bestehenden Spalts mit einer Heliumleckdichtigkeit von kleiner gleich 5 * 10^-10 mbar l/s bewirkt,
• c) einen ersten Fügungsbereich umfasst, der sich über den Oberflächenbereich des metallischen Körpers und den Oberflächenbereich des keramischen Körpers erstreckt, der außerhalb des Spalts angeordnet ist und den Spalt endseitig überdeckt, und/oder dessen sich über den Oberflächenbereich der Stirnseite des keramischen Körpers erstreckender Randbereich eine im Wesentlichen kreisringscheibenförmige Grundfläche aufweist und/oder eine Randbreite von größer gleich 0,4 mm und/oder kleiner gleich 1 mm aufweist, und/oder
• d) einen zweiten Fügungsbereich umfasst, der sich bis zu einer Spalthöhe in den Spalt hinein erstreckt, der einen Endbereich des metallischen Körpers außenseitlich allseitig umgibt, der den Spalt über eine Spalthöhe hinweg im Wesentlichen vollständig ausfüllt, und/oder der den Spalt über eine Spalthöhe von größer gleich 0,2 mm und/oder über eine Spalthöhe von kleiner gleich 1 mm hinweg im Wesentlichen vollständig ausfüllt.

A first development of the pressure sensor comprises a pressure sensor, in which
the main body forms the ceramic body or one of the ceramic bodies of the pressure sensor,
the metallic body or at least one of the metallic bodies is in each case formed as a pin extending through the main body, and
which the respective pin with the ceramic body ( 5 ) joined together in each case

• a) seals a gap existing between the pin and the ceramic body at the end,
• b) is designed such that it seals off a gap between the pin and the ceramic body with a helium leak tightness of less than or equal to 5 * 10 ^-10 mbar l / s,
• c) comprises a first joining region which extends over the surface region of the metallic body and the surface region of the ceramic body which is arranged outside the gap and which covers the gap at the end, and / or its edge region extending over the surface region of the end face of the ceramic body has a substantially annular disk-shaped base surface and / or has an edge width of greater than or equal to 0.4 mm and / or less than 1 mm, and / or
• d) comprises a second joint region which extends into the gap up to a gap height, which surrounds an end region of the metallic body on all sides on the outside, the gap over a gap height in the Essentially completely fills, and / or substantially completely fills the gap over a gap height of greater than or equal to 0.2 mm and / or over a gap height of less than or equal to 1 mm away.

A first embodiment of the pressure sensor comprises a pressure sensor which comprises at least one sensor component which is electrically contactable, electrically contacted, via the metallic body connected thereto, connected by the join or at least one of the joints with the ceramic body, passing through the ceramic body a measuring electronics can be connected or connected to a measuring electronics.

A second embodiment of the pressure sensor comprises a pressure sensor, in which the metallic body, at least one of the metallic bodies or all metallic bodies are each designed as solid cylinders with an outer diameter of 0.5 mm to 0.8 mm.

A second development of the pressure sensor comprises a pressure sensor which comprises at least one gap which is sealed on the end by the joining or one of the joints and which has a gap width of less than or equal to 0.02 mm sealed by the respective joint.

A third embodiment of the pressure sensor comprises a pressure sensor, the
is designed as an absolute pressure sensor with evacuated pressure chamber,
is formed as a relative pressure sensor, the pressure chamber can be acted upon by a running through the main body pressure supply line with a reference pressure, or
is designed as a differential pressure sensor.

• 1 zeigt: einen Drucksensor;
• 2 zeigt: den eingekreisten Ausschnitt A des Drucksensors von 1 vor der Ausführung des Fügeverfahrens; und
• 3 zeigt: den eingekreisten Ausschnitt A des Drucksensors von 1 nach der Ausführung des Fügeverfahrens.

The invention and its advantages will now be explained in more detail with reference to the figures of the drawing, in which an embodiment is shown. Identical elements are provided in the figures with the same reference numerals.

• 1 shows: a pressure sensor;
• 2 shows: the circled section A of the pressure sensor of 1 before the execution of the joining process; and
• 3 shows: the circled section A of the pressure sensor of 1 after the execution of the joining process.

The invention relates to a method for producing a pressure sensor which comprises at least one ceramic body connected by means of at least one joint to at least one metallic body. The ceramic body consists of a ceramic material, for example of an oxide ceramic, such as alumina (Al ₂ O ₃ ).

1 shows an example of a pressure sensor produced by the method of the invention described in detail below. This includes a pressure to be detected metrologically by the pressure sensor p loadable diaphragm 1 , which included a pressure chamber 3 with a ceramic body formed here as a basic body 5 connected is. In addition, the pressure sensor comprises at least one metallic body 7 that by at least one addition 9 with the ceramic body 5 the pressure sensor is connected.

1 shows as an example for this purpose a trained as a pin metallic body 7 that goes into one through the ceramic body 5 through bore used and end by means of the joint 9 with the ceramic body 5 connected is. The pin shown here as an example is formed as part of an electrical feedthrough, via the one to the metallic body 7 to be connected or to the metallic body 7 connected sensor component of the pressure sensor through the ceramic body 5 is electrically contacted, electrically contacted, to a measuring electronics 11 can be connected or to a measuring electronics 11 connected.

However, the invention is not on the in 1 shown example, but can be used completely analogously in conjunction with pressure sensors having a different shape, function and / or arrangement having ceramic body and / or other shape, function and / or arrangement having metallic body.

According to the invention as a metallic body 7 a body is used, one as an active component of one for active brazing of the ceramic body 5 suitable active braids usable active component comprises. In that regard, the metallic body 7 eg consist of the active component or of a material comprising the active component. As the active component are active metals, as they are already used in known from the prior art active hard soldering. As a metallic body 7 For example, a body consisting of titanium or titanium is preferably used. Alternatively, the metallic body 7 consist of another active metal, such as zirconium, hafnium or vanadium, or from a zirconium, hafnium or vanadium comprehensive material.

According to the invention, the addition 9 by means of a braze 13 generated, free from to Active brazing usable active components is. As a braze 13 For example, a silver-copper brazing alloy or another brazing material which, unlike active brazing solders used in the prior art for joining ceramic, such as silver-copper active brazing alloys, for example, contains no active component. As silver-copper brazing alloys, for example, only brazing alloys comprising silver and copper as well as another non-active component comprising silver-copper brazing alloys such as silver-copper-indium brazing alloys or silver-copper-tin brazing alloys are suitable. It is deliberately no active brazing used, although it is known that contained in active hard solder active components promote the wetting of the ceramic and react with the ceramic so that a mechanically high-strength chemical compound is formed by reducing the ceramic.

To create the addition 9 an arrangement is created that the ceramic body 5 , the metallic body 7 and the braze 13 includes. Subsequently, the assembly is heated to a bonding temperature at which the braze 13 is melted, a proportion of the metallic body 7 contained active component through the molten brazing alloy 13 through to the ceramic of the ceramic body 5 diffuses and reacts there with the ceramic in such a way that forms a chemical compound comprising the active component.

This method has the advantages already mentioned at the outset.

Another advantage is that hard solders, such as silver-copper brazing alloys, without active component have a lower melting temperature than an active component comprising active hard solders, such as silver, copper and titanium as active component comprising active hard solders. This offers the advantage that the joining process can be carried out at a joining temperature which is greater than or equal to the melting temperature of the brazing alloy 13 is, and which is less than a melting temperature of an active brazing alloy, which is in the brazing 13 contained components and those in the metallic body 7 contains contained active component.

While active brazing soldering produced above the melting temperature of the active hard solder in the range of 870 ° C. to 950 ° C. is required for the production of active brazing materials comprising silver, copper and titanium as the active component, one above the melting temperature is sufficient to carry out the process according to the invention the braze 13 lying joining temperature, which is sufficient to the diffusion of the active component through the molten brazing alloy 13 through. Consists of the metallic component 7 made of titanium or a titanium-containing material, this is sufficient in conjunction with a silver-copper brazing alloy already a joining temperature of less than or equal to 860 ° C in the range of 830 ° C to 860 ° C. In connection with a silver-copper-indium brazing alloy or a silver-copper-tin brazing alloy, depending on the proportionate composition of these brazing alloys, an even lower joining temperature can be applied.

A lower joining temperature offers the advantage that fewer thermo-mechanical stresses due to the joining process are formed in the pressure sensor than would be the case at higher joining temperatures. As a result, manufacturing-related, contained in the pressure sensor voltages can be reduced, which otherwise leads to an increase in temperature dependence of the pressure-dependent deformability of the measuring membrane 1 and / or a temperature-dependent measurement error could result.

The process according to the invention is esp. Of particular advantage, if with the addition 9 a comparatively narrow, between the ceramic body 5 and the metallic body 7 befindliches gap is sealed at the end. In this case, the method according to the invention has the advantage that the gap which is produced in this way and which seals the gap 9 even then a very high degree of tightness and a high compressive strength, when the braze 13 in the arrangement such on the one another by the addition 9 to be connected body 5 . 7 Although it is applied in that it is in direct contact with a surface area 15 of the metallic body 7 and in direct contact with a surface area 17 of the ceramic body 5 stands, one between the two surface areas 15 . 17 located end portion of the gap but only covered at the end.

2 shows an enlarged view of the in 1 circled section A of the pressure sensor of 1 after applying the braze 13 , There was the braze 13 applied so that it is formed on the surface area formed by an end face of the pin inserted into the bore in the base body 15 of the metallic body 7 rests. At the same time, the braze 13 so applied that it is on that surface area 17 of the ceramic body 5 rests on one end face of the ceramic body 5 immediately adjacent to the end region of the gap existing between the pin and the outer side surrounding this on all sides main body.

The braze 13 For example, it can be applied as a paste or applied as a solder preform.

Subsequently, a joining process is carried out, in which the assembly is heated to the joining temperature and after completion of the Joining again cools or cooled. 3 shows an enlarged view of the in 1 circled section A of the pressure sensor of 1 after the execution of the joining process.

During the joining process, a proportion diffuses in the metallic body 7 contained active component by the with the metallic body 7 in contact and / or in contact, molten brazing alloy 13 through to the surface area 17 of the ceramic body 5 , There, a chemical compound is formed by reducing the ceramic. The resulting addition 9 thus comprises a first joining region containing the active component 19 that is above the surface area 17 the front side of the ceramic body 5 extends.

In addition, molten brazing solder penetrates 13 into the gap. This process is esp. By the flow properties of the liquid brazing 13 , Capillary forces, wetting and / or chemical reaction initiated, assisted, enhanced and / or promoted. Again, a proportion diffuses in the metallic body 7 contained active component by the with the metallic body 7 in contact and / or in contact, molten brazing alloy 13 through to a the outer side surrounding the end region of the gap on all sides and / or the gap limiting lateral surface of the ceramic body 5 , where then forms a chemical compound by reducing the ceramic. The resulting addition 9 thus comprises a second mating region containing the active component 21 which extends into the gap.

During the joining process, wherever molten brazing material is formed 13 in direct contact with the metallic body 7 stands and / or in direct contact with the metallic body 7 one of the components of the brazing alloy 13 and the active component-containing alloy following to a portion of the joint 9 stiffens.

In this case, both the solidified portions comprising partial areas, as well as the chemical compound comprising parts of the resulting addition 9 a high pressure resistance and a high tightness.

The formed as a pin metallic body 7 may be formed, for example, as a solid cylinder with an outer diameter of 0.5 mm to 0.8 mm. In this case, the pin may have, for example, a length corresponding to the height of the main body, such as a length of greater than or equal to several millimeters, in particular of 4 mm to 5 mm, or even more than 5 mm.

The bore has a shape adapted to the shape of the pin shape. For this purpose, it may be formed, for example, as a cylindrical bore whose inner diameter is dimensioned such that between the ceramic body 5 and the metallic body 7 existing gap has a gap width of less than or equal to 0.02 mm. In this case, the gap may, for example, have a gap width determined essentially by manufacturing tolerances or at least co-determined by manufacturing tolerances.

How out 3 It can already be seen through the surface area 15 of the metallic body 7 and the surface area 17 of the ceramic body 5 extending, located outside the gap first mating area 19 both a pressure-resistant connection between the ceramic body 5 and the metallic body 7 causes, as well as an end seal of the first joint area 19 end overlapped gap causes.

Here, the first mating area 19 eg one above the surface area 17 the front side of the ceramic body 5 extending edge area 23 comprise, which has a substantially annular disc-shaped base surface, and / or which has an edge width b of greater than or equal to 0.4 mm and / or less than or equal to 1 mm.

The already through the first mating area 19 caused compressive strength of the joint 9 is additionally by the through the second mating area 21 caused compressive strength of the joint 9 strengthened. The same applies to the first section of the section 19 caused sealing of the gap in addition by the through the second mating area 21 reinforced sealing reinforced.

This leads during the joining process in the gap penetrating, molten brazing alloy 13 to that the second mating area 21 extends into the gap and / or the gap over a gap height H substantially completely. The gap height H corresponds essentially to a penetration depth, up to the molten brazing alloy 13 has penetrated into the gap together with the thereby diffusing active component during the joining process. In this case, the gap with the method according to the invention by the second joint area 21 up to a comparatively large gap height H , esp. A gap height h of greater than or equal to 0, 2 mm and / or a gap height H be filled by less than or equal to 1 mm.

In the in 3 illustrated example forms the second mating area 21 a substantially tubular, one end portion of the pin on the outside on all sides surrounding, connected to the end portion of the pin and the body second mating area 21 who has the gap over the entire in 3 drawn gap height H seals off.

By the method according to the invention is a very high tightness of the gap sealing joint 9 achieved. In this case, a conventional manner in the form of a helium leak rate specified helium leak tightness of the joint 9 of less than or equal to 5 * 10 ^-10 mbar l / s.

At the same time, of course, the second mating area also contributes 21 over the whole of the gap height H corresponding length to increase the compressive strength of the joint 9 at.

Alternatively or in addition to the in 1 shown, that of the measuring diaphragm 1 opposite end of the gap end sealing joint 9 Of course, on the membrane-facing side in the manner described above, a metallic body 7 end with the ceramic body 5 be created connecting joining.

Individual constituents of pressure sensors produced by means of the method according to the invention may have different embodiments which can be used individually or in combination with one another. Examples of this are described below with reference to FIGS.

Thus, the pressure sensor shown here as an example, for example, be designed as an absolute pressure sensor, the one on an outer side of the measuring diaphragm 1 acting pressure p metrologically recorded. In that case it is under the measuring membrane 1 enclosed pressure chamber 3 evacuated. Alternatively, the pressure sensor may be formed as a relative pressure sensor, one on the outside of the measuring diaphragm 1 acting pressure p relative to one of the pressure chamber 3 via a running through the body through, in 1 as an alternative dashed line pressure supply 25 supplied reference pressure p _ref detected. In addition, the invention can also be used analogously in conjunction with ceramic differential pressure sensors.

Regardless of the relevant embodiment, the pressure sensor comprises an electromechanical transducer, which is designed such that it from the on the measuring diaphragm 1 acting pressure dependent deflection of the measuring diaphragm 1 converted into an electrical quantity, which then by means of the connected to the transducer or connected to the transducer measuring electronics 11 can be metrologically detected and / or converted into a signal representing the pressure to be measured, which can then be displayed, output as a measurement signal and / or can be made available for further processing available. As electromechanical transducers known from the prior art transducers, such as optical, capacitive, piezoelectric or resistive transducer can be used.

1 shows as an example for this purpose a capacitive transducer, which has a measuring capacitor with one of the pressure-dependent deflection of the measuring diaphragm 1 dependent measuring capacity. The measuring capacitor comprises a measuring electrode applied on a membrane-facing end side of the main body 27 and one on the main body facing the inside of the measuring diaphragm 1 arranged counter electrode 29 ,

Regardless of the choice of electromechanical transducer, the pressure sensor may include one or more sensor components, such as the sensing electrode shown here 27 , which, in the manner described above, by means of the connected thereto, by the ceramic body 5 passing, in each case by means of a joint produced in the manner described above 9 with the ceramic body 5 connected, metallic body 7 is electrically connected.

Optionally, not only the main body, but also the measuring membrane 1 made of ceramic, for example of an oxide ceramic, such as alumina (Al ₂ O ₃ ) exist. In the case, basic body and measuring membrane 1 eg by means of an outer edge of the measuring diaphragm 1 connecting with an outer edge of the body, the pressure chamber 3 on the outside surrounding all sides active brazing 31 For example, active brazing produced by an active brazing agent comprising zirconium, nickel and titanium 31 to be connected. In the manufacture of this pressure sensor, for example, a step-soldering method can be used, in which active brazing is carried out in an active brazing method carried out at a higher joining temperature 31 and subsequently by means of the previously described joining method carried out at a lower joining temperature 9 between the metallic body 7 and the ceramic body 5 is produced. In this pressure sensor, the electrical connection of the counter electrode 29 for example, about the adjacent Aktivhartlötung 31 respectively. Alternatively, the electrical connection of the counter electrode 29 not shown here, through the body through to Aktivhartlötung 31 or up to one to the Aktivhartlötung 31 connected connecting portion extending further metallic body are contacted, which then preferably also by means of a joint produced in the manner described above 9 with the ceramic body 5 is connected.

LIST OF REFERENCE NUMBERS

1

measuring membrane

3

pressure chamber

5

ceramic body

7

metallic body

9

coincidence

11

measuring electronics

13

braze

15

Front side of the metallic body

17

Surface area of an end face of the ceramic body

19

first mating area

21

second mating area

23

border area

25

pressure supply line

27

measuring electrode

29

counter electrode

31

Aktivhartlötung

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008043567 A1 [0005]
• DE 102009003178 A1 [0010]

Claims (15)

Method for producing a pressure sensor comprising at least one ceramic body (5) connected to at least one metallic body (7) by means of at least one joint (9), in which as a metallic body (7) a body is used which comprises an active component which can be used as an active component of an active brazing agent of the ceramic body (5), producing an assembly comprising the ceramic body (5), the metallic body (7) and a brazing material (13), the brazing material (13) used being free from active brazing active components, and the assembly is heated to a bonding temperature at which the brazing alloy (13) is melted, a portion of the active component contained in the metallic body (7) through the molten body in contact with and / or in contact with the metallic body (7) Hard solder (13) through to the ceramic of the ceramic body (5) diffused and there reacts with the ceramic, that forms a chemical compound comprising the active component. Method according to Claim 1 in which the metallic body (7) consists of the active component or of a material comprising the active component, the active component consists of titanium, zirconium, hafnium or vanadium, the ceramic body (5) consists of an oxide ceramic or alumina (Al ₂ O ₃ ), and / or as hard solder (13) a silver-copper brazing alloy, a silver-copper indium brazing alloy, a silver-copper-tin brazing alloy or another brazing material is used. Method according to Claim 1 to 2 in which the joining process is carried out at a joining temperature which is greater than or equal to a melting temperature of the brazing alloy (13) and which is less than a melting temperature of an active brazing alloy comprising the components contained in the brazing alloy (13) and in the metallic body (5). includes contained active component. Method according to Claim 1 to 3 in that the metallic body (7) consists of titanium or a material comprising titanium, the ceramic body (5) consists of an oxide ceramic or of aluminum oxide (Al ₂ O ₃ ), as hard solder (13) a silver-copper brazing alloy is a silver Copper indium brazing alloy or a silver-copper-tin brazing alloy is used, and the assembly is heated to a joining temperature of less than or equal to 860 ° C in the range of 830 ° C to 860 ° C. Method according to Claim 1 to 4 in which the arrangement is produced such that the brazing material (13) is in direct contact with a surface region (15) of the metallic body (7) such that the brazing material (13) is in direct contact with a surface region (17) of the ceramic body (5), and that the brazing material (13) covers an end region of a gap between the metallic body (7) and the ceramic body (5) between the two surface regions (15, 17), a portion of the latter in the metallic body (7) contained active component through the with the metallic body (7) in contact and / or in contact, molten brazing solder (13) through to the surface region (17) of the ceramic body (5) diffused, where then Reduction of the ceramic forms a chemical compound, molten brazing material (13) penetrates into the gap, and a proportion of the metallic component (7) contained active component through the molten brazing material (13) which comes into contact and / or comes into contact with the metallic body (7) and diffuses to a lateral surface of the ceramic body (5) surrounding the gap on all sides and / or bounding the gap then forms a chemical compound by reducing the ceramic. Method according to Claim 5 in that the resulting joint (9) comprises a first joint area (19) extending over the surface areas (15) of the metallic body (5) and the surface area (17) of the ceramic body (5) arranged outside the gap is and covers the gap at its end, and / or its edge region (23) extending over the surface region (17) of an end face of the ceramic body (5) has a substantially annular disk-shaped base surface and / or a rim width (b) greater than or equal to 0, 4 mm and / or less than 1 mm. Method according to Claim 5 to 6 in which the resulting joint (9) comprises a second joint region (21) which extends into the gap up to a gap height (h) which surrounds an end region of the metallic body (7) on all sides on the outside, which surrounds the gap over one Gap (h) substantially completely fills, and / or substantially completely fills the gap over a gap height (h) of greater than or equal to 0.2 mm and / or over a gap height (h) of less than or equal to 1 mm, wherein the gap height (h) corresponds in each case to a penetration depth, up to that of the molten brazing alloy (13) has penetrated into the gap along with the thereby diffusing active component during the joining process. Method according to Claim 1 to 7 in which the metallic body (7) or at least one of the metallic bodies (7) is in each case formed as a pin, the respective pin is inserted into a bore extending through the ceramic body (5), and between the respective pin and the gap between the ceramic body (5) and the joint (9) connecting the respective pin to the ceramic body (5) is sealed at its end. Method according to Claim 1 to 8th in which, wherever molten brazing material (13) is in direct contact with the metallic body (7) and / or in direct contact with the metallic body (7), an alloy containing the components of the brazing alloy (13) and the active component is obtained forms, which subsequently solidifies to a portion of the joint (9). With a method according to Claim 1 to 9 produced pressure sensor which comprises a measurement membrane (1) which can be acted upon by a pressure (p) to be detected by the pressure sensor under inclusion of a pressure chamber (3) and which comprises an electromechanical transducer which is designed such that it has a by the pressure acting on the measuring diaphragm (1) pressure deflection of the measuring diaphragm (1) converts into an electrical variable, by means of a connected to the transducer or connected to the transducer measuring electronics (11) detected by measurement and / or and in a pressure to be measured (p) reproducing signal is convertible. Pressure sensor according to Claim 10 in which the base body forms the ceramic body (5) or one of the ceramic bodies of the pressure sensor, the metallic body (7) or at least one of the metallic bodies (7) is in each case designed as a pin passing through the base body, and the a) a gap between the pin and the ceramic body (5) sealing ends end b) is formed such that it seals a between the pin and the ceramic Body (5) gap having a helium leakage of less than or equal to 5 * 10 ^-10 mbar l / s causes, c) a first joint area (19) extending over the surface area (15) of the metallic body (5) and the surface area (17) of the ceramic body (5) which is arranged outside the gap and covers the gap at the end, and / or which extends over the surface area (FIG. 17) of the end face of the ceramic body (5) extending edge region (23) has a substantially annular disc-shaped base surface and / or a rim width (b) of greater than or equal to 0.4 mm and / or less than 1 mm, and / or d) a second joint region (21) which extends into the gap up to a gap height (h), which surrounds an end region of the metallic body (7) on all sides on the outside, which substantially completely fills the gap over a gap height (h) , and / or substantially completely fills the gap over a gap height (h) of greater than or equal to 0.2 mm and / or over a gap height (h) of less than or equal to 1 mm. Pressure sensor according to Claim 10 to 11 comprising at least one sensor component connected to the metallic body (7) connected thereto by the join (9) or at least one of the joints (9) connected to the ceramic body (5) and passing through the ceramic body (5). electrically contacted, electrically contacted, to a measuring electronics (11) can be connected or connected to a measuring electronics (11). Pressure sensor according to Claim 10 to 12 in which the metallic body (5), at least one of the metallic bodies (5) or all metallic bodies (5) are each formed as solid cylinders with an outer diameter of 0.5 mm to 0.8 mm. Pressure sensor according to Claim 10 to 13 which comprises at least one gap sealed by the join (9) or one of the joints (9) and having a gap width of less than or equal to 0.02 mm sealed by the respective joint (9). Pressure sensor according to Claim 10 to 14 , which is formed as an absolute pressure sensor with evacuated pressure chamber (3), is designed as a relative pressure sensor, the pressure chamber (3) via a through the main body extending through the pressure supply line (25) with a reference pressure (p _ref ) can be acted upon, or is designed as a differential pressure sensor.

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