DE102014115801A1 - Ceramic pressure sensor and method for its manufacture - Google Patents

Abstract

It is a ceramic pressure sensor with a pressure sensitive (p, p1, p2) acted upon, pressure-dependent elastically deformable ceramic measuring membrane (1), a base body (3, 29) and an outer edge of the measuring diaphragm (1) including a pressure chamber ( 5) with an outer edge of the measuring membrane (1) facing the end face of the base body (3, 29) connecting Aktivhartlötung (7) with improved measuring properties, and a method for its production described in which the improved measuring properties are achieved in that in a the measuring membrane (1) facing the edge region (17) of Aktivhartlötung (7) contained by targeted, spatially on the edge region (17) concentrated heating of the edge region (17) to an aftertreatment temperature (T), which is greater than or equal to a temperature at which the active brazing material is plastically deformable, can be reduced.

Description

The invention relates to a ceramic pressure sensor, with an acted upon by a pressure, pressure-dependent elastically deformable ceramic measuring membrane, a base body, and an outer edge of the measuring membrane, including a pressure chamber with an outer edge of the measuring membrane facing the end face of the body connecting Aktivhartlötung, and a Process for its preparation.

Ceramic pressure sensors comprise absolute pressure sensors which measure a pressure acting on the measuring diaphragm against vacuum, relative pressure sensors which measure the pressure acting on the measuring diaphragm relative to a reference pressure supplied to the pressure chamber, e.g. an atmospheric pressure, and differential pressure sensors that detect a pressure difference between two pressures acting thereon.

Ceramic pressure sensors of the type mentioned in the beginning are widely used today in almost all areas of industrial metrology.

• – einer mit einem Druck beaufschlagbaren, druckabhängig elastisch verformbaren keramischen Messmembran,
• – einem Grundkörper und
• – einer einen äußeren Rand der Messmembran unter Einschluss einer Druckkammer mit einem äußeren Rand einer der Messmembran zugewandten Stirnseite des Grundkörpers verbindenden Aktivhartlötung.

In the EP 490 807 A1 is a ceramic pressure sensor described with

• A pressure-sensitive elastically deformable ceramic measuring membrane which can be pressurized,
• - a basic body and
• - An active peripheral soldering connecting an outer edge of the measuring diaphragm with the inclusion of a pressure chamber with an outer edge of an end face of the base body facing the measuring diaphragm.

Measuring diaphragm and body of these pressure sensors consist e.g. of aluminum oxide and are pressure-tight joined by means of a Zr-Ni alloy and titanium ternary active brazing.

In the in the EP 490 807 A1 For this purpose, a solder layer between the measuring diaphragm and the base body is arranged, which is introduced as a prefabricated solder preform or alternatively applied as a solder paste. As an alternative, in the DE 10 2010 043 119 A1 described to apply the solder layer by vapor deposition on the outer edge of the measuring membrane and / or the base body.

The Aktivhartlötung takes place by the arrangement formed by the body, the solder layer and the measuring membrane is heated under vacuum in total to a lying above the melting temperature of the solder soldering soldering and held there for a longer period, esp. A period of 5 min to 15 min ,

Since the main body, the solder preform and the measuring diaphragm are heated to a total soldering temperature, it takes a correspondingly long time for the active brazing to cool down after the soldering operation. Long cooling periods favor the formation of coarse-grained structures by means of phase precipitations, which have a detrimental effect on the quality of active brazing, in particular its strength.

According to the DE 10 2011 005 665 A1 the quality of Aktivhartlötung of measuring diaphragm and body of ceramic pressure sensors can be improved by the solder layer disposed between the diaphragm and the base body is completely melted under vacuum by laser radiation. For this purpose, the laser radiation is directed through the outer edge of the measuring diaphragm onto the active hard solder. For complete melting of the solder layer, a laser is used for this purpose, which operates in a wavelength range in which the ceramic of the measuring membrane is substantially transparent. The molten active brazing material is kept at the brazing temperature by the laser irradiation for a period of not more than one minute. By the active brazing, only the solder layer is brought to the brazing temperature, the total heat energy supplied to the pressure sensor is lower, so that a faster cooling of Aktivhartlötung can be done. This provides less time for nucleation and growth of segregated phases.

The active hard solders used in the above known from the prior art method have a coefficient of thermal expansion, which is adapted to the thermal expansion coefficient of the ceramic body and measuring diaphragm. However, the coefficients of expansion are not identical, so that in spite of the comparatively good adaptation during cooling of the active brazing or of the pressure sensor from the brazing temperature to room temperature, mechanical stresses form in the pressure sensor. The largest voltages in terms of magnitude are formed where the materials with different thermal expansion coefficients meet. Accordingly, the stresses are concentrated both in an edge region of the active brazing facing the measuring membrane and in an edge region of the active brazing facing the base body.

While stresses in the edge region facing the base body have comparatively little effect with regard to the measuring properties, stresses in the edge region facing the measuring membrane have an effect directly on the pressure-dependent deformability of the measuring diaphragm and thus influence the measuring characteristics of the pressure sensor. These regularly variable voltages depending on the ambient temperature cause an additional temperature dependence of the measurement results. In addition, they can cause a dependent on the time course of the ambient temperature and / or the pressure to be measured hysteresis of the measurement results, which leads to a deterioration of the achievable measurement accuracy.

It is an object of the invention to provide a ceramic pressure sensor with improved measuring properties and a method for its production.

• – einer mit einem Druck beaufschlagbaren, druckabhängig elastisch verformbaren keramischen Messmembran,
• – einem Grundkörper, und
• – einer einen äußeren Rand der Messmembran unter Einschluss einer Druckkammer mit einem äußeren Rand einer der Messmembran zugewandten Stirnseite des Grundkörpers verbindenden Aktivhartlötung,

die sich dadurch auszeichnet, dass

• – die Aktivhartlötung einen der Messmembran zugewandten Randbereich aufweist, in dem darin enthaltene Spannungen durch gezieltes räumlich auf den Randbereich konzentriertes Erwärmen des Randbereichs auf eine Nachbehandlungstemperatur, die größer gleich einer Temperatur ist, bei der das Aktivhartlot plastisch verformbar ist, reduziert wurden.

To solve this problem, the invention comprises a ceramic pressure sensor, with

• A pressure-sensitive elastically deformable ceramic measuring membrane which can be pressurized,
• - a basic body, and
• An active brazing joining an outer edge of the measuring diaphragm, including a pressure chamber with an outer edge of an end face of the base body facing the measuring diaphragm,

which is characterized by the fact that

• - The Aktivhartlötung has a measuring membrane facing edge region in which stresses contained therein by targeted spatially focused on the edge region heating of the edge region to an aftertreatment temperature, which is greater than or equal to a temperature at which the active brazing material is plastically deformed, were reduced.

• – eine im Messbetrieb mit einem Druck beaufschlagbare, druckabhängig elastisch verformbare keramische Messmembran und ein Grundkörper vorgefertigt werden, und
• – ein äußerer Rand der Messmembran unter Einschluss einer Druckkammer mit einem äußeren Rand einer der Messmembran zugewandten Stirnseite des Grundkörpers mittels einer Aktivhartlötung verbunden wird,

das sich dadurch auszeichnet, dass

• – ein der Messmembran zugewandter Randbereich der Aktivhartlötung einer Nachbehandlung unterzogen wird, während der der Randbereich durch gezieltes, räumlich auf den Randbereich konzentriertes Erwärmen auf eine Nachbehandlungstemperatur aufgeheizt wird, die größer gleich einer Temperatur ist, bei der das Aktivhartlot plastisch verformbar ist.

The invention further includes a method for producing a ceramic pressure sensor, in particular a pressure sensor according to the invention, in which

• A pressure-sensitive, elastically deformable ceramic measuring membrane and a base body can be prefabricated during measurement operation, and
• An outer edge of the measuring diaphragm, including a pressure chamber, is connected to an outer edge of an end side of the main body facing the measuring diaphragm by means of active brazing,

which is characterized by the fact that

• - One of the measuring membrane facing edge region of Aktivhartlötung is subjected to a post-treatment, during which the edge region is heated by targeted, spatially concentrated on the edge region heating to an aftertreatment temperature which is greater than or equal to a temperature at which the active brazing material is plastically deformable.

A first variant of the method according to the invention provides that the edge region is heated to an aftertreatment temperature at which stresses existing in the edge region are essentially released by plastic deformation of the edge region.

According to one embodiment of the first variant, the after-treatment temperature is in a temperature range which includes temperatures which are greater than or equal to the solidus temperature of the active brazing alloy and exceed the solidus temperature by less than 50 ° C.

A second variant of the method according to the invention provides that the edge region is heated to an after-treatment temperature, in particular an aftertreatment temperature lying in the region of the soldering temperature of the active hard solder, at which the edge region melts.

According to a development of the method according to the invention, the heating of the edge region to the aftertreatment temperature is effected by laser irradiation by means of a laser aligned on the edge region, in particular of a pulse laser.

• – der Laser in einem Wellenlängenbereich arbeitet, in dem die Keramik der Messmembran im Wesentlichen transparent ist, und
• – die Laserbestrahlung des Randbereichs durch die Messmembran hindurch erfolgt.

A development of the latter training is characterized by the fact that

• The laser operates in a wavelength range in which the ceramic of the measuring diaphragm is substantially transparent, and
• - The laser irradiation of the edge region through the measuring membrane is carried out.

According to a development of the pressure sensor according to the invention, as well as the method according to the invention, the edge region has a layer thickness in the order of a few micrometers, esp. From 2 .mu.m to 3 .mu.m.

An advantage of the invention is that production-related stresses within the pressure sensor are deliberately reduced by the inventive spatially limited after-treatment of the measuring membrane facing edge region of Aktivhartlötung where they are particularly large and have a particularly adverse effect on the measurement properties of the pressure sensor. Not only are stresses within the edge region solved, but also an adaptation of the edge region to the stress conditions acting on the edge region takes place in its immediate surroundings.

In addition, the quality of the joint, in particular its strength, can be improved in the edge area by melting the edge area at the same time.

The heating of the edge region by means of a laser offers the advantage that the energy supply can be limited to a spatially very narrow range. In this case, the post-treatment temperature, the aftertreatment time and the dimensions of the edge region to be heated can be specified very precisely via a corresponding selection and activation of the laser.

A further advantage is that the end faces of the active soldering edge region to be heated are enclosed between the measuring diaphragm and the core area of the active hard soldering. While Aktivhartlötungen due to the reactivity of the active brazing must be performed regularly under vacuum or under a protective gas atmosphere, the aftertreatment can be due to the addition of the comparatively small edge surfaces complete inclusion of the edge region between the measuring membrane and the core region to atmosphere.

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

1 shows: a ceramic pressure sensor;

2 shows: an increase in active brazing of 1 ; and

3 shows: a ceramic differential pressure sensor.

1 shows a section through an embodiment of a ceramic pressure sensor. This comprises a pressure diaphragm p acted upon and pressure-dependent elastically deformable measuring diaphragm 1 on a base 3 is arranged.

The measuring membrane 1 and preferably also the basic body 3 consist of ceramics, for example of alumina (Al ₂ O ₃ ), and are together, including a pressure chamber 5 pressure-tight connected. For this purpose, an outer edge of the main body 3 facing side of the measuring diaphragm 1 including the pressure chamber 5 by means of active brazing 7 with an outer edge of one of the measuring membrane 1 facing end face of the body 3 connected. The active brazing material used for this purpose is preferably a ternary active brazing filler having a Zr-Ni alloy and titanium, as described, for example, in the aforementioned US Pat EP 490 807 A2 is described.

The illustrated pressure sensor can be designed as an absolute pressure sensor. In that case it is under the measuring membrane 1 enclosed pressure chamber 5 evacuated. Alternatively, it may be formed as a relative pressure sensor by the pressure chamber 5 about one through the main body 3 Leading through, in 1 dashed bore 9 a reference pressure p _ref , for example, an atmospheric pressure is supplied, based on the on the measuring diaphragm 1 acting pressure p is to be detected.

The pressure sensor comprises an electromechanical transducer, which serves to a pressure-dependent deformation of the measuring diaphragm 1 metrologically to capture. In the exemplary embodiments illustrated here, a capacitive converter is provided for this purpose, which has at least one capacitor with a function of the pressure-related deflection of the measuring diaphragm 1 having changing capacity. This includes one on a body 3 facing side of the measuring diaphragm 1 applied electrode 11 and one on one of the measuring membrane 1 facing end face of the body 3 applied counter electrode 13 , The pressure-dependent capacity of this capacitor or its changes are via a to the electrode 11 and the counter electrode 13 connected, not shown here measuring electronics detected and converted into a pressure-dependent measurement signal, which is then available for display, for further processing and / or evaluation.

The pressure sensor is made by measuring diaphragm 1 and basic body 3 prefabricated. For this purpose, for example, sintering methods can be used, in which measuring membrane 1 and basic body 3 are each made of a granulate, which is filled into a correspondingly shaped prefabricated mold, pressed in the mold and then sintered.

Subsequently, the sintered bodies obtained in this way, as far as e.g. is required due to the desired shape of these components or tolerances to be observed, be subjected to a corresponding mechanical hard machining. For this purpose, hard machining methods such as e.g. Turning, milling, drilling, sawing, lapping or grinding can be used.

Following, if necessary, hard machining of measuring diaphragm 1 and / or basic body 3 become the electrode 11 and the counter electrode 13 on the corresponding faces of measuring diaphragm 1 and basic body 3 applied, eg sputtered flat. It can at the same time a electrical connection of the counter electrode 13 be provided by a contact pin 15 , eg a tantalum pin, into one through the main body 3 leading bore is used, which is an electrically conductive connection to the counter electrode 13 manufactures.

Below are measuring diaphragm 1 and basic body 3 including the pressure chamber 5 actively bonded together by active brazing pressure-tight. This is between the by the active brazing 7 to be joined outer facing edges of body 3 and measuring membrane 1 arranged a solder layer. The solder layer can be applied, for example, as solder paste or in the form of a prefabricated solder preform, for example a solder ring. As solder preforms, for example, in the EP 490 807 A1 described Lotformteile be used. These have a minimum thickness of the order of 30 .mu.m due to the melt-spinning process used for their production.

A smaller minimum thickness of the measuring membrane 1 and basic body 3 connecting active brazing 7 and, concomitantly, a lower electrode spacing, which is more advantageous in order to achieve a higher measuring accuracy, can be carried out according to a method described in US Pat DE 10 2010 043 119 A1 be achieved described method. This is the one for active brazing 7 required active brazing material applied by vapor deposition on the joining surfaces. This allows Aktivhartlötungen 7 be made with a lower height h, for example, with a height h in the order of 10 microns.

After the introduction or application of the solder layer is through the body 3 , the solder layer and the measuring membrane 1 formed assembly under vacuum to a soldering temperature above the melting temperature of the active brazing heated and maintained there for a longer period, esp. A period of 5 min to 15 min.

Alternatively, the aforementioned in the DE 10 2011 005 665 A1 described Aktivhartlötverfahren be used in which the solder layer is completely melted under vacuum by laser radiation. The molten active brazing material is held by the laser irradiation for a period of not more than one minute at a brazing temperature which is greater than or equal to the liquidus temperature of the active brazing above which the active brazing material is completely liquefied.

At the soldering temperature, the active component of the active brazing material, here titanium, reacts with the ceramic. In this case, a reduction of the ceramic causes a mechanically high-strength chemical bond between the ceramic and the active brazing material.

Soldering temperatures above 800 ° C., in particular soldering temperatures in the range from 880 ° C. to 920 ° C., are regularly required in conjunction with the abovementioned Zr-Ni alloy and titanium-containing ternary active hard solder.

During the subsequent cooling of the Aktivhartlötung 7 or the pressure sensor from the soldering temperature to the ambient temperature form due to the similar, but not identical thermal expansion coefficients of active brazing and ceramic stresses. The greatest amount of stress arises where the two materials meet directly. Accordingly, the stresses concentrate both in one of the measuring membrane 1 facing edge area 17 active brazing 7 , as well as in one of the main body 3 facing edge area 19 active brazing 7 ,

2 shows a not to scale enlargement of the in 1 circled section of the measuring membrane 1 and basic body 3 connecting active brazing 7 , The two border areas 17 . 19 each comprise a tie layer 21 in which the chemical bond between the ceramic of the measuring membrane caused by active brazing 1 and the active brazing material or between the ceramic of the base body 3 and the active hard solder, and one to the respective connection layer 21 immediately adjacent active brazing layer 23 active brazing 7 ,

The border areas 17 . 19 in which form the largest tensions, have regularly compared to the height h of Aktivhartlötung 7 small layer thickness d in the order of a few micrometers, esp. In the order of 2 microns to 3 microns, on.

Tensions in the body 3 facing edge area 19 are relatively uncritical with regard to the measuring characteristics of the pressure sensor. On the other hand, stresses in the measuring membrane have an effect 1 facing edge area 17 active brazing 7 directly on the pressure-dependent deformability of the measuring membrane 1 out, and thus lead to the above-mentioned impairment of the measuring characteristics of the pressure sensor.

According to the invention, the active brazing 7 the pressure sensor subjected to a post-treatment, which serves to the voltages in the measuring diaphragm 1 facing edge area 17 to reduce. This is done by targeted spatially on the edge area 17 concentrated heating of the edge area 17 ,

For targeted spatially on the edge area 17 limited heating is preferably a laser 25 used. Particularly suitable for this are pulse lasers which generate laser pulses of short duration. The energy supply caused by the laser pulses is spatially even more limited, the shorter the pulse duration. In that regard, for example, picosecond lasers are suitable. An even higher spatial limit can be achieved by the use of femtosecond lasers.

The laser irradiation of the edge area 17 preferably takes place through the measuring membrane 1 therethrough. This will be a laser 25 used, which operates at a wavelength that is used to a large extent by the active brazing material, but not or at least only to a much lesser extent by the ceramic of the measuring diaphragm 1 , is absorbed. For example, CO ₂ or Nd-YAG lasers with wavelengths in the visible to near infrared range are suitable for this purpose in conjunction with the abovementioned aluminum oxide ceramic and the Zr-Ni alloy and titanium-containing ternary active hard solder. The measuring membrane 1 Insofar, it preferably consists of a ceramic, which is characterized by a low density of scattering centers in the visible wavelength range. For this purpose, esp. High purity alumina ceramics, such as those in the DE 10 2008 036 381 B3 are described.

The laser irradiation can, for example, on the in 2 manner shown by the laser 25 above the measuring membrane 1 arranged, and by means of a beam guiding device 27 on the edge area 17 active brazing 7 is aligned. Following are lasers 25 and pressure sensor is moved relative to each other such that the laser beam, the entire base of the edge region 17 sweeps. In this case, the laser power and irradiation time corresponding to the post-treatment temperature, on the edge area 17 should be heated, and the post-treatment period, while the edge area 17 is to be maintained at the post-treatment temperature. In addition, the temperature of the edge area 17 monitored by pyrometric temperature measurements.

According to the invention, the edge region 17 heated to an after-treatment temperature which is greater than or equal to that temperature from which the active brazing material used is plastically deformable.

Due to the introduced heat energy tensions dissolve in the edge area 17 , At the same time, the higher the aftertreatment temperature is, the faster the stress builds up 17 is heated. Accordingly, the aftertreatment time over which the edge area 17 is maintained at the after-treatment temperature, depending on the after-treatment temperature, wherein at higher post-treatment temperatures shorter after-treatment periods are required and vice versa. The after-treatment time is, depending on the post-treatment temperature, for example, in the order of a few seconds.

In order to reduce stresses caused by active brazing, it is sufficient to use the edge area 17 to heat to a post-treatment temperature T, in the edge region 17 plastic deformations occur. This is already the case in a near range below the solidus temperature of the active hard solder temperatures. Preferably, the post-treatment temperature is in a temperature range comprising temperatures greater than the solidus temperature of the active brazing alloy and exceeding the solidus temperature by less than 50 ° C. In connection with the abovementioned Zr-Ni alloy and titanium-containing ternary active hard solder, a temperature range of 800 ° C. to 850 ° C. results for this purpose.

With these after-treatment temperatures, which are low in comparison to the melting temperature of the active hard solder, the stress reduction essentially takes place due to plastic deformation within the edge region 17 instead of. In addition, the border area adjusts 17 by plastic deformation optimally to the stress conditions in its immediate vicinity, so that also on the measuring diaphragm 1 and the core area of active brazing 7 on the edge area 17 applied stresses due to plastic deformation of the edge area 17 be reduced. As a result, at least in part, such stresses are reduced by a previous hard machining of the measuring diaphragm 1 into the measuring membrane 1 and over the tie layer 21 on the edge area 17 Act.

At higher post-treatment temperatures, an increase in the structure within the edge region occurs to an increasing extent 17 ,

By the treatment according to the invention of the edge region 17 Thus, not only can stresses be reduced, but also targeted changes in the structure of the structure in the aftertreated edge area 17 be made. This is the border area 17 preferably heated to an aftertreatment temperature at which the edge region 17 melts. This is the case in the area of the soldering temperature of the active brazing material.

By melting the edge area 17 Tensions are in the border area 17 completely solved. During the subsequent solidification, the edge area also optimally adapts to the Tension conditions in the immediate vicinity, so that here too within the edge area 17 existing, as well as over the measuring membrane 1 and the core area of active brazing 7 in the border area 17 into it acting stresses are reduced by the aftertreatment.

As in the aftertreatment only the compared to the total volume of Aktivhartlötung 7 comparatively small border area 17 is melted, this much less heat energy is required than in the previously performed Aktivhartlötung. Accordingly, can be when cooling the edge area 17 achieve significantly higher cooling rates. High cooling rates cause the edge area 17 solidified to a finer grain structure with higher strength. As a result of the aftertreatment, not only are the stresses affecting the measuring characteristics reduced but at the same time the quality, in particular the strength, of the active brazing 7 in that due to its direct connection to the measuring membrane 1 mechanically most stressed edge area 17 improved.

The invention can be used completely analogously also in conjunction with ceramic pressure sensors designed as differential pressure sensors. 3 shows an embodiment of a differential pressure sensor with a ceramic body 23 , on whose opposite end faces in each case a measuring diaphragm 1 is arranged. Each of the measuring membranes 1 is in each case including a pressure chamber 5 via active brazing 7 with her facing end face of the body 29 connected. The pressure chambers 5 are filled with a pressure-transmitting liquid and a likewise filled with a pressure-transmitting liquid pressure transmission line 31 connected with each other. In measuring mode, the first measuring diaphragm 1 with a first pressure p ₁ and the second measuring diaphragm 1 subjected to a second pressure p ₂ and the resulting, depending on the pressure difference between the first and the second pressure p ₁ , p ₂ deflection of at least one of the two measuring membranes 1 detected by means of an electromechanical transducer, such as a capacitive transducer, metrologically, and converted into a corresponding differential pressure measurement signal.

In accordance with the invention, the respective measuring diaphragm is also used here 1 facing edge region of the two Aktivhartlötungen 7 the basis of 1 subjected to post-treatment described.

LIST OF REFERENCE NUMBERS

1

 measuring membrane

3

 body

5

 pressure chamber

7

 Aktivhartlötung

9

 drilling

11

 electrode

13

 counter electrode

15

 pin

17

 border area

19

 border area

21

 link layer

23

 Active braze layer

25

 laser

27

 Beam guiding device

29

 body

31

 Pressure transmission line

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

• EP 490807 A1 [0004, 0006, 0036]
• DE 102010043119 A1 [0006, 0037]
• DE 102011005665 A1 [0009, 0039]
• EP 490807 A2 [0030]
• DE 102008036381 B3 [0048]

Claims (9)

Ceramic pressure sensor, with - a pressure-dependent elastically deformable ceramic measuring membrane (p, p ₁ , p ₂ ) ( 1 ), - a basic body ( 3 . 29 ), and - one outer edge of the measuring membrane ( 1 ) including a pressure chamber ( 5 ) with an outer edge of one of the measuring membrane ( 1 ) facing end side of the base body ( 3 . 29 ) connecting active brazing ( 7 ), characterized in that - active brazing ( 7 ) one of the measuring membrane ( 1 ) facing edge region ( 17 ) in which stresses contained therein by targeted spatially on the edge area ( 17 ) concentrated heating of the edge area ( 17 ) were reduced to an after-treatment temperature (T) which is greater than or equal to a temperature at which the active brazing material is plastically deformable. A method for producing a ceramic pressure sensor, esp. A pressure sensor according to claim 1, wherein - a in the measuring operation with a pressure (p, p ₁ , p ₂ ) acted upon, pressure-dependent elastically deformable ceramic measuring membrane ( 1 ) and a basic body ( 3 . 29 ), and - an outer edge of the measuring membrane ( 1 ) including a pressure chamber ( 5 ) with an outer edge of one of the measuring membrane ( 1 ) facing end side of the base body ( 3 . 29 ) by means of active brazing ( 7 ), characterized in that - one of the measuring membranes ( 1 ) facing edge region ( 17 ) of active brazing ( 7 ) is subjected to an aftertreatment, while the 17 ) by targeted, spatially on the edge area ( 17 ) heated to a post-treatment temperature which is greater than or equal to a temperature at which the active brazing material is plastically deformable. Method according to claim 2, characterized in that the edge region ( 17 ) is heated to an aftertreatment temperature at which in the edge region ( 17 ) existing stresses essentially by plastic deformation of the edge region ( 17 ) to solve. A method according to claim 3, characterized in that the aftertreatment temperature is in a temperature range comprising temperatures which are greater than the solidus temperature of the active brazing alloy and exceed the solidus temperature by less than 50 ° C. Method according to claim 2, characterized in that the edge region ( 17 ) is heated to an after-treatment temperature, in particular an aftertreatment temperature lying in the region of the soldering temperature of the active hard solder, in which the edge region ( 17 ) melts. Method according to claim 2, characterized in that the heating of the edge region ( 17 ) on the post-treatment temperature by laser irradiation by means of a on the edge area ( 17 ) aligned laser ( 25 ), esp. Of a pulse laser, takes place. Method according to claim 6, characterized in that - the laser ( 25 ) works in a wavelength range in which the ceramic of the measuring membrane ( 1 ) is substantially transparent, and - the laser irradiation of the edge region ( 17 ) through the measuring membrane ( 1 ) through. Pressure sensor according to claim 1, characterized in that the edge region ( 17 ) has a layer thickness (d) in the order of a few micrometers, esp. From 2 .mu.m to 3 .mu.m. Method according to claim 2, characterized in that the edge region ( 17 ) has a layer thickness (d) in the order of a few micrometers, esp. From 2 .mu.m to 3 .mu.m.

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