DE102016107238A1 - Method for joining a differential pressure measuring cell and differential pressure measuring cell - Google Patents

Abstract

The invention relates to a method for joining a differential pressure measuring cell (1) and a differential pressure measuring cell (1) produced by the method. In the method joining material (FM) on the measuring membrane (2) facing end face (13a) of the first support body (51) and / or on the measuring membrane (2) facing away from the end face (12a) of the first counter body (41) and on the the measuring membrane (2) facing the end face of the second support body (13b) and / or on the measuring membrane (2) facing away from end face (12b) of the second counter body (42) applied. On at least one of the end faces (12a; 12b; 13a; 13b), the joining material (FM) is applied in a structured manner during application so that the end face (12a; 12b; 13a; 13b) has areas with (32) and areas without (31) joining material (FM). In the pressure-tight connection of counter body (41; 42) and support body (51; 52), the enlargement (82) of the joining material (FM) in the plane parallel to the end face (12a; 12b; 13a; enlarged with joining material (FM) and the areas (31) without joining material (FM) reduced so that gradually a substantially single contiguous area (9) with joining material (FM) is formed, and counter-body (41; 42) and supporting body (51 ; 52) are joined substantially over the entire surface.

Description

The invention relates to a method for joining a differential pressure measuring cell and a differential pressure measuring cell produced by the method.

Differential pressure measuring cells have to measure the difference between two static pressures p1 and p2 on a measuring diaphragm, which is arranged to form two hermetically separated measuring chambers between two counter-bodies. The measuring chambers are each acted upon by the pressures p1 and p2 via pressure channels introduced into the counter-bodies. A deflection of the measuring diaphragm is thus a measure of the pressure difference | p1 - p2 |, whereby the deflection of the diaphragm is converted by means of a transducer into an electronic measuring signal. For example, forms in capacitive differential pressure measuring cells, the measuring diaphragm together with a measuring membrane facing and parallel to the measuring membrane and conductive plane of the counter body a capacitor. Thus, the deflection of the measuring diaphragm determines the distance between the condenser, so that the differential pressure acting on the measuring diaphragm can be converted into a measuring signal by means of capacitance measurements. Such a pressure difference measuring cell is for example in the patent DE 103 94 943 B3 described. Pressure difference measuring cells, which are used in the process and / or automation technology of industrial plants for monitoring process pressures, are manufactured and distributed by the E + H Group in a wide variety of designs.

Because differential pressure cells are designed to have low pressure differences | p1 - p2 | With simultaneous high static pressures p1, p2, the right balance between sensitivity and overload protection is of central importance. For example, for the measuring range of the pressure difference | p1 - p2 | the following relationship applies: | p1 - p2 | / p1 <1%. Not applicable in a process plant of either pressure (e.g., p2), | p1 - p2 | / p1 reaches nearly 100%. In this case, the differential pressure measuring cell is thus loaded with more than 100 times the measuring range, which corresponds to a very high unilateral pressure load. For differential pressure cells with a very fine measuring range of | p1 - p2 | ~ 10 mbar is the one-sided pressure load in relation to the measuring range correspondingly higher at a typical process pressure of 160 bar.

The prior art discloses various embodiments for overload protection of differential pressure measuring cells at high static pressures p1, p2, including, for example, overload membranes (US Pat. EP 1 299 701 B1 . DE 10 2006 040 325 A1 or DE 10 2006 057 828 A1 ) or membrane beds ( US 4,458,537 or DE 10 2009 046 229 A1 ).

A very high pressure load can also lead to a deformation of the counter body itself. As a result, the stability of the differential pressure measuring cell is significantly influenced, for example by the support function of the membrane beds is impaired. In the context of construction and connection technology of a differential pressure measuring cell, it is therefore intended to enclose the counter-body between two support body, wherein the support body is used for stabilization and can counteract a deformation of the counter body. Typically, the support body is made of a material having a modulus of elasticity which is at least as great as that of the counter body. For the best possible support of the counter body on the support body, it is advantageous if there is a stiff connection between the counter body and support body. Examples of a stiffening of the support body / counter body interface are in the JP 57040626 A1 or the DE 10 2012 113 033 A1 disclosed.

In the assembly and connection technology of silicon-based microelectromechanical systems (MEMS), the individual components are joined with a glass solder. In this process, referred to as glass solder bonding, the joining material is generally not applied over the entire surface, but applied in the form of a fine frame, the so-called bond frame. In this way, no full-surface connection between the individual components is achieved. In contrast, in a differential pressure measuring cell based on a MEMS sensor, it is desirable that the connecting plane between the mating body and the supporting body be joined over the entire surface. As a result, the most rigid possible connection between the mating body and the support body can be obtained, which is of great importance for the stability of the differential pressure measuring cell or the overload protection.

The invention is based on the object to provide a method for joining a differential pressure measuring cell in order to obtain a stable differential pressure measuring cell.

• – wobei zwischen der Messmembran und dem ersten Gegenkörper eine erste Messkammer und zwischen der Messmembran und dem zweiten Gegenkörper (42) eine zweite Messkammer gebildet wird,
• – wobei der erste Gegenkörper und erste Stützkörper sowie der zweite Gegenkörper und zweite Stützkörper einen Druckkanal aufweisen, durch den die erste Messkammer mit einem ersten Druck und die zweite Messkammer mit einem zweiten Druck beaufschlagbar ist und
• – wobei der Wandler dazu ausgestaltet ist, ein elektrisches Messsignal aus einer durch die Differenz zwischen dem ersten Druck und dem zweiten Druck bedingte Verformung der Messmembran zu erzeugen; wobei sich das Fügen in folgende Verfahrensschritte unterteilt:
• – Vorfertigung der beiden Gegenkörper und druckdichtes Verbinden der Messmembran mit den beiden Gegenkörpern
• – Aufbringen eines Fügematerials auf die der Messmembran zugewandte Stirnfläche des ersten Stützkörpers und/oder auf die der Messmembran abgewandte Stirnfläche des ersten Gegenkörpers und auf die der Messmembran zugewandte Stirnfläche des zweiten Stützkörpers und/oder auf die der Messmembran abgewandte Stirnfläche des zweiten Gegenkörpers, wobei auf mindestens einer der Stirnflächen das Fügematerial bereichsweise aufgetragen wird, so dass Bereiche mit Fügematerial und Bereiche ohne Fügematerial gebildet werden,
• – Druckdichtes Verbinden der jeweils der Messmembran abgewandten Stirnfläche des Gegenkörpers mit der der Messmembran zugewandten Stirnfläche des Stützkörpers, wobei während dem Verbinden von zumindest einem der Gegenkörper mit dem angrenzenden Stützkörper das Fügematerial in der Stirnfläche mit dem bereichsweise aufgetragenen Fügematerial in der zu der Stirnfläche senkrechten Richtung verkleinert und in mindestens einer zu der Stirnfläche ebenen Richtungen vergrößert wird, wobei durch die Vergrößerung des Fügematerials in der zu der Stirnfläche ebenen Richtung die Bereiche mit Fügematerial vergrößert und die Bereiche ohne Fügematerial verkleinert werden, so dass allmählich ein einziger zusammenhängender Bereich mit Fügematerial gebildet wird, welcher Bereich sich bis auf eine den Druckkanal umgebende innere Ausparung über die gesamte Stirnfläche erstreckt, so dass nach dem druckdichten Verbinden Gegenkörper und Stützkörper im Wesentlichen vollflächig gefügt sind.

The object is achieved by methods for joining a differential pressure measuring cell, which differential pressure measuring cell comprises: a measuring diaphragm; a transducer, a first and a second counter body and a first and a second support body wherein the measuring diaphragm between the first counter body and the second counter body is arranged and pressure-tightly connected to two counter-bodies,

• Wherein between the measuring diaphragm and the first mating body a first measuring chamber and between the measuring diaphragm and the second mating body ( 42 ) a second measuring chamber is formed,
• - Wherein the first counter-body and the first support body and the second counter-body and the second support body have a pressure channel through which the first measuring chamber with a first pressure and the second measuring chamber can be acted upon with a second pressure and
• - wherein the transducer is adapted to generate an electrical measurement signal from a caused by the difference between the first pressure and the second pressure deformation of the measuring diaphragm; wherein the joining is subdivided into the following method steps:
• - Prefabrication of the two counter-body and pressure-tight connection of the measuring membrane with the two counter-bodies
• Applying a joining material to the end face of the first support body facing the measuring membrane and / or to the end face of the first opposing body facing away from the measuring membrane and to the end face of the second support body facing the measuring membrane and / or to the end face of the second opposing body facing away from the measuring membrane at least one of the faces of the joining material is applied in areas, so that areas are formed with joining material and areas without joining material,
• - Pressure-tight connection of each of the measuring membrane facing away from the end face of the mating body with the measuring membrane facing end face of the support body, wherein during the joining of at least one of the mating body with the adjacent support body, the joining material in the end face with the partially applied joining material in the direction perpendicular to the end face direction is reduced in size and enlarged in at least one direction to the end face, wherein the enlargement of the joining material in the direction flat to the end face increases the areas with joining material and the areas are reduced without joining material, so that gradually a single contiguous area is formed with joining material , Which region extends up to an inner recess surrounding the pressure channel over the entire end face, so that, after the pressure-tight connection, the opposing body and the supporting body essentially cover the entire surface are joined.

In the first step of the method according to the invention, therefore, the two counter-bodies are first prefabricated. During the pressure-tight connection of the measuring diaphragm with the two counter-bodies, the measuring diaphragm is arranged between the two counter-bodies and the measuring chambers are formed. The prefabrication in the first method step also includes the arrangement of all those components between the counter bodies, which are required for the generation or conversion of the measurement signal, such as the membrane electrodes and the transducer. The two support bodies are prefabricated.

In the second step of the method according to the invention, the joining material is applied structured in the end face of a counter body and / or support body. The structuring is carried out so that there are separate areas with and without joining material after application of the joining material. The full-surface joined compound is not obtained by the fact that the joining material is applied flat, but the joining material is initially applied only in certain areas and then increased in the pressure-tight connection in a plane to the end face direction. In this way, in the connection of the mating body and the supporting body, finally, a single contiguous, very homogeneous area with joining material is formed in the connection between the mating body and the supporting body.

As a result, a surface which is essentially completely empty (except for a recess surrounding the pressure channel) is achieved between the mating body and the support body. As a result, a differential pressure measuring cell with a very stable connection between the mating body and the support body, and thus a total of a differential pressure measuring cell of high stability is obtained with the inventive method.

If the joining material is applied to the end face of the support body in the method according to the invention, then the pressure-tight connection between the support body and the counter body takes place in a subsequent method step. This is a point in time which lies before the process step of the pressure-tight connection. In the context of this application, in this case "the end face of the support body facing the measuring diaphragm" is that end face which is provided for connection to the end face of the counter body remote from the measuring diaphragm. The measuring membrane facing the end face of the support body is thus the one which is to be combined in the positioning of the counter body and support body with the measuring membrane facing away from the end face of the counter body. The end face of the mating body and the supporting body is substantially in a plane parallel to the measuring diaphragm plane.

In one embodiment of the method according to the invention, the joining material is at least partially in the form of at least one Annular ring applied, wherein the inner recess is located in the center of the annulus. A circular ring is defined in this application as the area bounded by two concentric circles. A circular ring has a circular ring width, which is given by the difference of the radii of the two concentric circles. In the case of several concentric circular rings, the circular rings can also be of different circular ring width. If the joining material is applied only in certain areas, segments of circular rings are present.

The aim in the procedure for achieving the full-surface joint connection of the counter body and support body is that the joining material by the enlargement of the joining material in the direction flat to the end surface forms the first only partially applied joining material substantially the shape of a circular surface, the inner Ausparung in the center the circular area lies. In the pressure-tight bonding, the joining material is then evenly distributed over the entire connecting plane between the mating body and the support body by the further enlargement of the circular surface-shaped joining material in the direction flat to the end face.

In a development of this embodiment of the method according to the invention, the joining material is applied in the form of several concentric circular rings on the end face, wherein the inner recess is located in the center of the circular surface.

In a further embodiment of the method, a region without joining material is provided as the venting region. The venting area extends from the inner recess to an edge area of the end face. During the pressure-tight connection, the ventilation area is continuously reduced in size by continuously filling the ventilation area from the inner recess to the edge area with joining material. In this advantageous embodiment, the ventilation area is gradually closed by the continuous filling with joining material starting from the inner recess. The air which is enclosed in the vent area can escape via the pressure channel and / or the edge area arranged inside the inner recess. This ensures that no air pockets form in the joining material. For example, the vent area is a wedge-shaped area without joining material between two circular ring sections of a circular ring of joining material.

In a particularly advantageous embodiment of the method according to the invention, the joining material is applied on the end face of the opposing body facing away from the measuring membrane in a first region and on the end face of the adjoining support body in a second region complementary to the first region. The two complementary areas complement each other to a given geometric shape. In the context of this application, the adjoining supporting body is that supporting body which is provided for positioning on the end face of the counter-body facing away from the measuring membrane. Since the two complementary areas complement each other to a predetermined shape, the first area represents the negative of the second area and vice versa.

In this particularly advantageous embodiment of the method counter-body and support body can be aligned with each other during pressure-tight connection by the mutually complementary regions of joining material snugly fit into each other to form the predetermined geometric shape. Depending on the nature of the joining material, the exact application and metering of the joining material is easier than the exact alignment of the mating body and support body to each other. On the basis of the structuring of the joining material in predetermined areas of the end face, a self-alignment of the counter body and the supporting body relative to one another can therefore be achieved with the method according to the invention.

In a further development, the mutually complementary regions have the form of concentric circular rings and / or sections of concentric circular rings. The given geometric shape is thus essentially a circular area or the totality of concentric circular rings.

The joining material is applied, for example, in the form of mutually complementary sections of concentric circular rings on the end face of the counterpart body facing away from the measuring diaphragm and on the end face of the adjacent supporting body facing the measuring diaphragm. In this way, complete concentric circular rings of joining material are formed by the fitting-like engagement of the mutually complementary sections of concentric circular rings. The complete concentric circular rings then form the coherent area with joining material during pressure-tight bonding.

It is also possible within the scope of the invention to apply first concentric circular rings on the end face of the mating body facing away from the measuring diaphragm and second concentric annular rings of the joining material on the end face of the adjacent mating body facing the diaphragm. The first and second concentric circular rings complement each other to form common concentric circular rings, wherein the annular width of the common concentric circles is the sum of the annular widths of the first and second is concentric circles. For example, the first concentric circular rings can be arranged within the second concentric circular rings. In this way, the common concentric circular rings are formed. In this case, areas without joining material can continue to be provided between the common concentric circular rings as long as a single contiguous area with joining material is formed during the pressure-tight bonding by the enlargement of the joining material in the direction flat to the end face, which extends substantially over the entire end face.

In a further embodiment of the method, the joining material is applied by means of a screen printing process. Since in screen printing process the metering and / or structuring of the joining material is very easily adjustable or controlled, these are particularly suitable for the inventive method. For example, in the screen-printing process, it is possible to use computer-aided methods to produce automatically produced screen-printing matrices. Thus, very well-defined patterns of joining material can be applied to the end face and a high degree of automation in the production of differential pressure measuring cells can be achieved by means of the method according to the invention.

As joining material, in one embodiment of the method according to the invention, a glass solder, adhesive or metallic solder is used. The glass solder is especially used when joining MEMS-based differential pressure cells.

In a further embodiment of the method, the joining material is applied with a predeterminable layer thickness, whereby in the pressure-tight bonding the predefinable layer thickness decreases in the direction perpendicular to the end face to a resulting predefinable layer thickness. The joining material has a layer thickness dv after application. For example, the layer thickness dv after the reduction of the joining material in the direction perpendicular to the end face by 20-40% smaller. Thus, the resulting layer thickness is 20-40% smaller than the predefinable layer thickness dv. The predeterminable resulting layer thickness dr is approximately between 5-50 micrometers. In the case of a glass solder, the resulting layer thickness of the joining material is substantially between 10-20 microns.

In a further embodiment of the method, the counterpart body is connected in a pressure-tight manner to the adjoining support body with an approximately homogeneous contact pressure distribution and with a predeterminable contact pressure Pf. If the contact pressure distribution is substantially homogeneous, a substantially constant resulting layer thickness of the joining material is achieved after the pressure-tight bonding. Since the contact pressure is usually even better adjustable or controllable than the layer thickness of the joining material during application and / or the surface structure of the prefabricated counter body and support body, a particularly homogeneous full-surface connection of the support body and the counter body is achieved in this embodiment.

In general, the counter body and / or the support body on at least one axis of symmetry, wherein the counter body and / or the support body is substantially symmetrical with respect to the axis of symmetry. The axis of symmetry may be, for example, the mirror axis of a mirror symmetry, or else the axis of rotation of a rotational symmetry. The symmetry axis can lie in the plane of the end face, or be perpendicular to the end face. In an advantageous development of the method, the joining material is structured in at least one of the end surfaces so that the joining material is arranged substantially symmetrically about at least one axis of symmetry. The axis of symmetry is thus a common axis of symmetry of the support body and / or counter-body and the joining material.

• – wobei die Messmembran zwischen dem ersten Gegenkörper und dem zweiten Gegenkörper angeordnet und mit beiden Gegenkörpern druckdicht verbunden ist,
• – wobei zwischen der Messmembran und dem ersten Gegenkörper eine erste Messkammer und zwischen der Messmembran und dem zweiten Gegenkörper eine zweite Messkammer gebildet ist,
• – wobei der erste Gegenkörper und Stützkörper und der zweite Gegenkörper und Stützkörper jeweils einen Druckkanal aufweisen, durch den die erste Messkammer mit einem ersten Druck (p1) und die zweite Messkammer mit einem zweiten Druck (p2) beaufschlagbar ist und
• – wobei der Wandler dazu ausgestaltet ist, ein elektrisches Messsignal aus einer durch die Differenz zwischen dem ersten Druck (p1) und dem zweiten Druck (p2) bedingte Verformung der Messmembran zu erzeugen;

wobei die der Messmembran abgewandte Stirnfläche von zumindest einem der Gegenkörper mit der der Messmembran zugewandten Stirnfläche des angrenzenden Stützkörpers druckdicht und im Wesentlichen vollflächig verbunden ist.The invention includes a differential pressure measuring cell, wherein the differential pressure measuring cell was obtained from the method according to the invention, comprising; a measuring membrane; a transducer, a first and a second counter body, and a first and a second support body,

• Wherein the measuring diaphragm is arranged between the first counter-body and the second counter-body and is pressure-tightly connected to both counter-bodies,
• Wherein a first measuring chamber is formed between the measuring diaphragm and the first counterbody and a second measuring chamber is formed between the measuring diaphragm and the second counterbody,
• - Wherein the first mating body and support body and the second mating body and support body each have a pressure channel through which the first measuring chamber with a first pressure (p1) and the second measuring chamber with a second pressure (p2) can be acted upon and
• - wherein the transducer is adapted to generate an electrical measurement signal from a caused by the difference between the first pressure (p1) and the second pressure (p2) deformation of the measuring diaphragm;

wherein the measuring membrane facing away from the end face of at least one of the counter-body with the measuring membrane facing the end face of the adjacent support body is pressure-tight and connected substantially over the entire surface.

In one embodiment of the invention, the support body and / or the counter body consists of a ceramic material.

In a further embodiment, the support body and / or the counter body consists essentially of silicon (Si), of an amorphous or crystalline oxide (SiO 2), carbide (SiC) and / or nitride (Si 3 N 4) of the silicon and / or of an amorphous or crystalline oxide (Al 2 O 3) and / or nitride of aluminum (AlN). The carbide of silicon, which can be present in many energetically almost equivalent polytopes, is suitable because of its high hardness. On the other hand, silicon nitride has a slightly lower hardness, but has a high breaking strength in combination with a low coefficient of thermal expansion and a relatively small modulus of elasticity. Silicon dioxide usually forms as a native, at least nanometer thick oxidation layer on silicon, silicon carbide or silicon nitride in contact with ambient air.

On the basis of the choice of the combination of materials, the modulus of elasticity of the components of the differential pressure measuring cell can be adjusted. In a further development of the invention, the modulus of elasticity of the support body is adjusted so that it is equal to or greater than the modulus of elasticity of the counter body. As an upper limit, the modulus of elasticity of the support body in this development should be at most three times as large as the modulus of elasticity of the counterpart body. In this embodiment, the support body is thus at least as stable as the counter body.

The invention will be explained in more detail with reference to the following figures. It shows:

1 : An embodiment of the method according to the invention and a differential pressure measuring cell obtained by the method according to the invention

2a , b: A obtained by the method according to the invention

Differential pressure measuring cell

3 : A further embodiment of the method according to the invention

4 : A further embodiment of the method according to the invention

In 1 is a plan view of the measuring membrane 2 opposite end face 12a of the first mating body 41 (left) and the measuring membrane 2 facing end face 13a of the first support body 51 (right) shown. The method step shown here is the application of the structured joining material FM to that of the measuring membrane 2 facing end face 13a of the first support body 51 , The first method step of the method according to the invention (the prefabrication of the two counter bodies 41 . 42 and the pressure-tight connection of the measuring membrane 2 with the two counter bodies 41 . 42 ) has preceded the process step of applying the joining material FM. The measuring diaphragm ME thus lies in the connection plane of the two counter-bodies 41 . 42 , The to the faces 12a . 12b vertical side surfaces of the mating body 41 . 42 are shown as hatched areas. In the center of the measuring membrane 2 facing end face 13a of the first support body 51 is the pressure channel 7 arranged over which the measuring chamber 61 can be acted upon by the pressure p1.

The joining material FM is applied to the measuring membrane 2 zugwandten face 13a of the support body 51 applied in a structured manner. In the case shown here, the joining material FM was applied in the form of concentric circular rings. Also, an axis of symmetry SA is shown, around which the joining material FM is arranged symmetrically. The process of pressure-tight connection is indicated by the dashed arrows in FIG 1 indicated.

2a is a schematic side view of a cross section of the differential pressure measuring cell according to the invention 1 during the pressure-tight connection according to the method according to the invention. For orientation were in 1 and 2a the straight line AB (dashed line) drawn. The concentric circular rings of the joining material FM 1 are in 2a now in profile. When pressure-tight connection, the counter body 41 and the support body 51 now connected to the contact pressure Pf a uniform contact pressure distribution. Thereby, the joining material FM becomes the end face 13a reduced in the vertical direction 81 and in the radial direction 82 the concentric circles increased. In this case, the predefinable initial layer thickness dv of the joining material FM is reduced to the resulting layer thickness dr of the joining material FM.

2 B is a schematic side view of a cross section of the differential pressure measuring cell according to the invention 1 , which with the inventive method 1 was obtained. The measuring membrane 2 , which has a diameter dM, is between the two counter bodies 41 . 42 arranged. The diameter dM in the context of this application is the diameter of the measuring diaphragm 2 in the area of the measuring chamber 61 ; 62 , The opposing bodies 41 . 42 are with the measuring diaphragm 2 forming the measuring chambers 61 . 62 pressure-tight connected to each other. The two measuring chambers 61 . 62 can each have a pressure channel 7 with the pressures p1 and p2 be applied. In the pressure-tight connection according to the invention in Essentially one to one the pressure channel 7 surrounding inner recess 15 full-surface joint between opposing body 41 and supporting body 51 reached.

In this embodiment was in both faces 13a . 13b structured the joining material FM. Nonetheless, the components described below may also be part of a differential pressure measuring cell according to the invention 1 in which the connection between both counter bodies 41 . 42 and the adjacent support body 51 . 52 were added according to the inventive method. It should be noted that the schematic representation shown here is by no means true to scale.

The differential pressure measuring cell 1 further comprises a capacitive transducer (not shown here) which receives one of a difference of the two pressures | p1 - p2 | dependent deflection of the measuring diaphragm 2 converts into an electrical signal. For this purpose, the two counter-bodies 41 . 42 For example, each at its diaphragm-side end face 11a . 11b at least one measuring electrode 10a . 10b on, with the measuring diaphragm 2 both sides a membrane electrode 14a . 14b having a measuring electrode 10a . 10b is facing. In a simple embodiment of the capacitive converter, the pressure difference | p1 - p2 | to be measured results from the difference between the reciprocal values of the capacitances between in each case one measuring electrode 10a . 10b and the opposite membrane electrode 14a . 14b , The sum of the capacity inversion values can be used to determine the static pressure p1, p2, to which the pressure difference | p1 - p2 | is superimposed. To increase the accuracy of measurement, the end faces of the counter body 41 . 42 each have a circular disk-shaped central electrode and a surrounding, in particular capacitance equal, ring electrode. Details of the wiring of such a capacitive transducer are known and, for example, in EP 1 883 797 B1 disclosed.

For detecting the static pressure p1, p2, at least one further capacitive transducer can be provided, which in each case has an electrode at the measuring diaphragm 2 opposite end face 12a . 12b of the opposite body 41 . 42 or the measuring membrane 2 facing end face 13a . 13b of the support body 51 . 52 having. Similarly, a resistive transducer for detecting the static pressure p1, p2 may be provided, wherein the support body 51 . 52 or counterbody 41 . 42 in this case has deformation-dependent resistance elements. The latter may for example comprise strain gauges, wherein in the case of a differential pressure measuring cell 1 comprising a semiconductor material, piezoresistive resistive elements are preferable.

In 3 is, analogous to 1 , the application of the joining material FM according to the inventive method in a plan view of the two end faces 12a . 13a shown. The reference numerals are identical to those in FIG 1 and 2 In this embodiment, the joining material FM became both on the measuring membrane 2 opposite end face 12a of the opposite body 41 as well as on the measuring membrane 2 facing end face 13a of the adjacent support body 51 applied. The joining material FM on the measuring membrane 2 opposite end face 12a of the opposite body 41 forms a first area 17a a predetermined geometric shape 18 , In both faces 12a . 13a are the areas with 32 and without 31 Joining FM is structured so that the two complementary areas 17a . 17b be formed. The predeterminable geometric shape 18 Here are concentric circular rings, and the two complementary areas 17a . 17b consist of circular ring sections of the concentric circular rings.

In 4 is the vent area 16 or the continuous filling of the venting area 16 shown with joining material FM. The ventilation area 16 is in this embodiment, a wedge-shaped opening in an otherwise circular area 32 with joining material FM. The wedge-shaped opening 16 extends from the inner recess 15 starting at the edge area RB. The otherwise circular area 32 with joining material FM is a contiguous area 32 with joining material FM. He can also from concentric circular rings (see. 1 ) with a common vent area 16 emerged. In the pressure-tight connection is through the joining material FM in the to the measuring membrane 2 facing end face 12a of the opposite body 51 plane directions increased, and so the vent area 16 gradually filled (from left to right) with joining material FM. In this way one becomes the inner Ausparung 15 surrounding area 32 formed with joining material FM without air pockets.

LIST OF REFERENCE NUMBERS

1

 Differential pressure measuring cell

2

 measuring membrane

31

 Area without joining material

32

 Area with joining material

41

 first counter body

42

 second counter body

51

 first support body

52

 second support body

61

 first measuring chamber

62

 second measuring chamber

7

 pressure channel

81

 Reduction of the joining material

82

 Enlargement of the joining material

9

 contiguous area with joining material

10a

 measuring electrode

10b

 measuring electrode

11a

 the measuring membrane facing end face of the first counter body

11b

 the measuring membrane facing end face of the second counter body

12a

 the measuring membrane facing away from the end face of the first counter body

12b

 the measuring membrane facing away from the end face of the second counter body

13a

 the measuring diaphragm facing end face of the first support body

13b

 the measuring membrane facing end face of the second support body

14a

 membrane electrode

14b

 membrane electrode

15

 inner cutout

16

 vent area

17a

 first area

17b

 second area

18

 specifiable geometric shape

p1

 first pressure

p2

 second pressure

FM

 Add material

RB

 border area

ME

 Measuring membrane level

SA

 axis of symmetry

dv

 predefinable layer thickness

dr

 predefinable resulting layer thickness

It

 Elastic modulus of the support body

Eg

 Young's modulus of the counter body

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 10394943 B3 [0002]
• EP 1299701 B1 [0004]
• DE 102006040325 A1 [0004]
• DE 102006057828 A1 [0004]
• US 4458537 [0004]
• DE 102009046229 A1 [0004]
• JP 57040626 A1 [0005]
• DE 102012113033 A1 [0005]
• EP 1883797 B1 [0041]

Claims (14)

Method for joining a differential pressure measuring cell ( 1 ), which differential pressure measuring cell ( 1 ) comprises: a measuring membrane ( 2 ); a transducer, a first and a second counter body ( 41 . 42 ), and a first and a second support body ( 51 . 52 ), - whereby the measuring membrane ( 2 ) between the first counterbody ( 41 ) and the second counter body ( 42 ) and with both counter bodies ( 41 . 42 ) is connected pressure-tight, - wherein between the measuring diaphragm ( 2 ) and the first counterbody ( 41 ) a first measuring chamber ( 61 ) and between the measuring membrane ( 2 ) and the second counter body ( 42 ) a second measuring chamber ( 62 ) is formed, - wherein the first counter body ( 41 ) and first support body ( 51 ) as well as the second counterbody ( 42 ) and second support body ( 51 ) a pressure channel ( 7 ) through which the first measuring chamber ( 61 ) with a first pressure (p1) and the second measuring chamber ( 62 ) is acted upon with a second pressure (p2) and - wherein the transducer is configured to an electrical measurement signal from a by the difference between the first pressure (p1) and the second pressure (p2) caused deformation of the measuring diaphragm ( 2 ) to create; wherein the joining is subdivided into the following method steps: - prefabrication of the two counter bodies ( 41 . 42 ) and pressure-tight connection of the measuring membrane ( 2 ) with the two counter bodies ( 41 . 42 ), - applying a joining material (FM) to the measuring membrane ( 2 ) facing end face ( 13a ) of the first support body ( 51 ) and / or on the measuring membrane ( 2 ) facing away from the end face ( 12a ) of the first counterbody ( 41 ) and on the measuring membrane ( 2 ) facing end face ( 13b ) of the second support body ( 51 ) and / or on the measuring membrane ( 2 ) facing away from the end face ( 12b ) of the second counter body ( 42 ), wherein on at least one of the end faces ( 12a ; 12b ; 13a ; 13b ) the joining material (FM) is applied in regions, so that areas ( 32 ) with joining material (FM) and areas ( 31 ) are formed without joining material (FM), - Pressure-tight connection of each of the measuring membrane ( 2 ) facing away from the end face ( 12a . 12b ) of the counterbody ( 41 . 42 ) with the measuring membrane ( 2 ) facing end face ( 13a . 13b ) of the supporting body ( 51 . 52 ), wherein during the connection of at least one of the counter bodies ( 41 ; 42 ) with the adjacent support body ( 51 ; 52 ) the joining material (FM) in the end face ( 12a ; 12b ; 13a ; 13b ) with the partially applied joining material (FM) • in the end face ( 12a ; 12b ; 13a ; 13b ) vertical direction ( 81 ) and • in at least one of the end face ( 12a ; 12b ; 13a ; 13b ) plane directions ( 82 ), whereby due to the magnification ( 82 ) of the joining material (FM) in the end face ( 12a ; 12b ; 13a ; 13b ) plane direction the areas ( 32 ) with joining material (FM) and the areas ( 31 ) without joining material (FM), so that gradually a single contiguous area ( 9 ) is formed with joining material (FM), which region ( 9 ) except for an inner gap surrounding the pressure channel ( 15 ) over the entire face ( 12a ; 12b ; 13a ; 13b ), so that after the pressure-tight connection, the opposing body ( 41 ; 42 ) and supporting body ( 51 ; 52 ) are joined substantially over the entire surface. Method according to claim 1, wherein the joining material (FM) is applied at least in regions in the form of at least one circular ring, and wherein the inner recess (FIG. 15 ) lies in the center of the annulus. Method according to claim 1 or 2, wherein the joining material (FM) is applied at least in regions in the form of a plurality of concentric circular rings, and wherein the inner recess (FIG. 15 ) lies in the common center of the concentric circular rings. Method according to at least one of the preceding claims, wherein an area ( 31 ) without joining material (FM) as vent area ( 16 ), which ventilation area ( 16 ) from the inner recess ( 15 ) starting up to an edge region (RB) of the end face ( 12a ; 12b ; 13a ; 13b ), and wherein during the pressure-tight connection the vent area ( 16 ) is continuously reduced by the vent area ( 16 ) from the inner recess ( 15 ) is continuously filled to the edge region (RB) with joining material (FM). Method according to at least one of the preceding claims, wherein the joining material (FM) on the measuring membrane ( 2 ) facing away from the end face ( 12a ; 12b ) of the counterbody ( 41 ; 42 ) in a first area ( 17a ) and on the face ( 13a ; 13b ) of the adjacent support body ( 51 ; 52 ) in a second, the first area ( 17a ) complementary area ( 17b ) is applied, and wherein the two mutually complementary areas ( 17a . 17b ) to a given geometric shape ( 18 ) complete. Method according to claim 5, where the complementary areas ( 17a . 17b ) have the form of concentric circular rings and / or sections of concentric circular rings, so that the given geometric shape ( 18 ) is substantially a circular area or concentric circular rings. Method according to at least one of the preceding claims, wherein the joining material (FM) is applied by means of a screen printing process. Method according to at least one of the preceding claims, wherein a glass solder, an adhesive, or a metallic solder is used as the joining material (FM). Method according to at least one of the preceding claims, wherein the joining material (FM) is applied with a predefinable layer thickness (dv), wherein in the pressure-tight bonding the predefinable layer thickness (dv) in the to the end face ( 12a ; 12b ; 13a ; 13b ) vertical direction to a resulting predefinable layer thickness (dr) reduced. Method according to at least one of the preceding claims, wherein the counterbody ( 41 . 42 ) with the adjacent support body ( 51 . 52 ) is pressure-tightly connected with an approximately homogeneous contact pressure distribution with a contact pressure (Pf). Differential pressure measuring cell ( 1 ) obtained from a method according to at least one of the preceding claims 1-10; a measuring membrane ( 2 ); a transducer, a first and a second counter body ( 41 . 42 ), and a first and a second support body ( 51 . 52 ), - whereby the measuring membrane ( 2 ) between the first counterbody ( 51 ) and the second counter body ( 52 ) and with both counter bodies ( 51 . 52 ) is connected pressure-tight, - wherein between the measuring diaphragm ( 2 ) and the first counterbody ( 51 ) a first measuring chamber ( 61 ) and between the measuring membrane ( 2 ) and the second counter body ( 52 ) a second measuring chamber ( 61 ), wherein the first counterbody ( 41 ) and first support body ( 51 ) and the second counter body ( 42 ) and second support body ( 52 ) each have a pressure channel ( 7 ) through which the first measuring chamber ( 61 ) with a first pressure (p1) and the second measuring chamber ( 62 ) is acted upon by a second pressure (p2) and - wherein the transducer is adapted to generate an electrical measurement signal from a caused by the difference between the first pressure (p1) and the second pressure (p2) deformation of the measuring diaphragm; where the measuring membrane ( 2 ) facing away from the end face ( 12a ; 12b ) of at least one of the counter bodies ( 41 ; 42 ) with the measuring membrane ( 2 ) facing end face ( 13a ; 13b ) of the adjacent support body ( 51 ; 52 ) is pressure-tight and connected substantially over the entire surface. Differential pressure measuring cell ( 1 ) according to claim 10 or 11, wherein the counterbody ( 41 ; 42 ) and / or the supporting body ( 51 ; 52 ) consists of a ceramic material. Differential pressure measuring cell ( 1 ) according to at least one of the preceding claims 11-12, wherein the counterbody ( 41 ; 42 ) and / or the supporting body ( 51 ; 52 ) - of silicon (Si), - of an amorphous or crystalline oxide of silicon (SiO2), amorphous or crystalline carbide (SiC) of silicon and / or amorphous or crystalline nitride (SiN) of silicon, - and / or of an amorphous or crystalline oxide of aluminum (Al 2 O 3) and / or nitride of aluminum (AlN). Differential pressure measuring cell ( 1 ) according to at least one of the preceding claims 11-13, wherein the modulus of elasticity (Es) of the supporting body ( 51 ; 52 ) equal to or greater than the elastic modulus (Eg) of the counter body ( 41 ; 42 ), wherein the elastic modulus (Es) of the supporting body ( 51 ; 52 ) at most three times as large as the elastic modulus (Eg) of the counter body ( 51 ; 52 ).

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