WO2015039811A1

WO2015039811A1 - Measuring instrument with a semiconductor sensor and a metallic supporting body

Info

Publication number: WO2015039811A1
Application number: PCT/EP2014/067181
Authority: WO
Inventors: Andreas Rossberg; Elke Schmidt
Original assignee: Endress+Hauser Gmbh+Co. Kg
Priority date: 2013-09-19
Filing date: 2014-08-11
Publication date: 2015-03-26
Also published as: DE102013110376A1

Abstract

A measuring instrument (100) comprises a semiconductor sensor with a sensor body (120) of a semiconductor material; and a metallic supporting body (131), which are connected by way of at least one intermediate body (110), which is formed as a compensating body and has first and second end regions (111, 113), with first and second materials and first and second effective coefficients of thermal expansion and comprises between the end regions (111, 113) a transitional region (112), in which the effective coefficient of thermal expansion changes from the first to the second coefficient of thermal expansion, wherein the transitional region has a series of layers with a mixture of at least the first material and the second material, wherein the mixing ratio of the layers varies in order to achieve a progressive change in the coefficient of thermal expansion, wherein the first end region (111) of the compensating body is facing the sensor body (110) and the second end region (113; 213) of the compensating body is facing the supporting body (131), wherein the effective coefficient of thermal expansion of the end regions deviates from those of the adjacent bodies by no more than 2 ppm/K.

Description

Measuring device with a semiconductor sensor and a metallic support body

The present invention relates to a measuring device, in particular pressure measuring device with a semiconductor sensor, in particular semiconductor pressure sensor.

Arrangements are given in metrology, in particular process measurement technology, in which a semiconductor sensor is arranged on a metallic support body in a metallic housing and is mechanically coupled to the metal support body. The mechanical coupling can in particular take place via intermediate bodies made of glass or Kovar and include joints, which serve in particular to stress due to the

different thermal expansion coefficients of, for example, about 15 ppm / K for the common stainless steels, and less than 4 ppm / K for silicon, to keep away from the semiconductor pressure sensor. The joints have in particular solders or adhesives. Although the described coupling of the semiconductor sensor to the housing via intermediate body quite fulfills its purpose, come to the

Interfaces between the bodies materials with different

Thermal expansion coefficient together, so that thermomechanical

Stresses due to different thermal expansion also from the

Joint, so a lot or an adhesive to be included. this leads to

Drift or hysteresis of the measurement signal. Furthermore, most pressure-sensitive adhesives swell under the influence of moisture, as a result of which drift and hysteresis problems can likewise occur. It is therefore the object of the present invention to remedy this situation.

The present invention is based on the idea that

Thermal expansion differences continuously or reduce in small steps. An approach to give body, which are prepared by sintering metallic-ceramic, metallic-glassy and / or ceramic glassy powder layers.

Sintered bodies are known, for example, from the IMW Industrial Communication No. 29 (2004) by Trenke entitled "Selective Laser Sintering of Metallic / Ceramic

It is therefore fundamentally possible to solidify powders in layers by means of laser sintering, these powders containing mixtures of metallic and ceramic particles, in which way solid bodies can be prepared by layerwise variation of the composition to prepare a compensating body which the production of a

Inventive measuring device according to claim 1 allows. The measuring device according to the invention comprises: a semiconductor sensor having a sensor body made of a semiconductor material, in particular Si, a metallic support body, and an intermediate body, wherein the sensor body via the at least one intermediate body, which is arranged between the sensor body and the support body, with the support body wherein the compensating body comprises: a first end portion having a first material having a first effective thermal expansion coefficient oii, a second end portion having a second material having a second effective thermal expansion coefficient a ₂ has, one

Transition region between the first end region and the second end region, in which the effective thermal expansion coefficient from the first effective coefficient of thermal expansion to the second effective

Thermal expansion coefficient changes, wherein the transition region comprises a series of layers with a mixture of at least the first material and the second material, wherein the mixing ratio of the layers varies to achieve a stepwise, in particular monotonous, change in the thermal expansion coefficient, wherein the first end of the

Balancing body the sensor body and the second end of the

Balancing body faces the support body, wherein the first effective

Coefficient of thermal expansion of the first end region of the balancing body from the coefficient of thermal expansion of a material of one to the first

End region of the balancing body adjacent body by not more than 2 ppm / K, in particular not more than 1 ppm / K differs, wherein the second effective thermal expansion coefficient of the second end portion of the balancing body substantially the coefficient of thermal expansion of the second

End region of the balancing body adjoining body deviates by not more than 2 ppm / K, in particular not more than 1 ppm / K, and wherein the second effective thermal expansion coefficient is greater than the first effective

Thermal expansion coefficient.

Insofar as regions or layers of particles sintered together can be composed, local variations in the thermal expansion coefficient can occur. An effective coefficient of thermal expansion of a region or layer designates the macroscopic coefficients of thermal expansion averaged over the region or layer. The measuring device according to the invention can in particular be a pressure measuring device, a flow measuring device, a density measuring device and / or a potentiometric

Measuring device, wherein the semiconductor sensor, a pressure sensor, a

Flow sensor, a density sensor, and / or a potentiometric sensor, such as an isFET includes.

In a development of the invention, the first end region of the

Balancing body a glass, in particular a borosilicate glass. A borosilicate glass, such as Pyrex, has a coefficient of thermal expansion that is compatible with that of silicon, which is the currently preferred material of the

Semiconductor sensor is.

In one development of the invention, the first end region of the compensation body is pressure-tightly joined to the sensor body, in particular by anodic bonding.

In a further development of the invention, the second end region of the compensating body is joined to the adjoining body in a pressure-tight manner, in particular by soldering, brazing or welding. The adjacent body may be either the Stützkorper or an intermediate body, which in turn is held by the support body. However, in terms of a simple construction, it is premature if the second end portion is joined directly to the support body.

In a development of the invention, the second end region is a

Intermediate body joined, which is arranged between the support body and the compensation body, wherein the intermediate body comprises Kovar.

In a development of the invention, the support body comprises steel. The support body may in particular be designed as a so-called T08 socket, with which the sensor body is held in a sensor chamber in the interior of a metallic housing.

In one development of the invention, the layers of the transition region of the compensation body are substantially parallel to one another. In one development of the invention, the transition region of the compensation body has a maximum perpendicular to a direction of the layer sequence

Extension d, wherein the transition region in the direction of the layer sequences has a height h, where:

where Δα is the difference between the first effective coefficient of thermal expansion and the second coefficient of thermal expansion, and where ξ is a constant of dimension 1 / K, for which

ξ <0.1% / K, in particular <500 ppm / K, preferably <250 ppm / K, more preferably <125 ppm / K and particularly preferably <60 ppm / K.

In one embodiment of this development of the invention, the following applies:

AT

where ΔΤ = (T _max -T _min ), is the size of a specified operating temperature range for the meter, and where C is a dimensionless deformation parameter for which C <4%, in particular C <2% and preferably C <1%.

This development of the invention implicitly defines minimum requirements for the height h of the transition region over which thermal expansion differences are to be reduced. The defined requirements are intended to ensure that the strength limits of the transitional area are not exceeded.

In one development of the invention, the transition region has a maximum extent d perpendicular to a direction of the layer sequence, wherein one layer has an average layer height s, where:

the

s

where Aas is the difference of the effective coefficients of thermal expansion of the layers adjacent to this layer, and where ξ is a constant with the

Dimension 1 / K, for which: ξ <0.1% / K, in particular <500 ppm / K,

preferably <250 ppm / K, more preferably <125 ppm / K and particularly preferably <60 ppm / K. In one embodiment of this development of the invention, the following applies:

where ΔΤ = (T _max -T _min ) is the size of a specified operating temperature range for the meter, and where Cs is a dimensionless deformation parameter for which C _s <4%, in particular <2% and preferably <1%. This development of the invention implicitly defines minimum requirements for the layer thickness S of the individual layers of the transitional region over which

Thermal expansion differences are to be reduced. The defined requirements are intended to ensure that the strength limits of the transitional area are not exceeded microscopically.

The specified operating temperature range ΔΤ may be, for example, about 100K to 200K or 250K. In a development of the invention, the first material is a ceramic

Material or a glass, in particular Pyrex, and has a thermal expansion coefficient of not more than 5 ppm / K, in particular not more than 4 ppm / K, wherein the second material is a metallic material having a coefficient of thermal expansion of not less than 10 ppm / K, in particular not less than 13 ppm / K and further not less than 15 ppm / K.

In one development of the invention, the layers in the transition region have a layer height h of not less than 10 μm, in particular not less than 20 μm, and preferably not less than 40 μm, wherein the layers in the

Transition region each have a layer height h of not more than 400 μιη, in particular not more than 200 μιη and preferably not more than 100 μιη have.

In one development of the invention, the transition region N has layers each having a different effective thermal expansion coefficient, the value of which lies between the first thermal expansion coefficient αι and the second thermal expansion coefficient a ₂ , the number N being not less than (Δα) / (2 ppm / K) , especially not less than (Δα) / (1 ppm / K) and preferably not less than (2Δα) / (1 ppm / K).

The given minimum number of layers in the transition region ensures that local stress peaks between the layers are limited.

In one development of the invention, the first and / or the second end region has or have a height that is at least half the height of the

Transitional area, in particular not less than the height of the

Transition region and preferably not less than twice the height of the transition region. A multiplicity of compensation bodies can be prepared in the wafer assembly, wherein, for example, mixtures of glass and metal particles are deposited in layers on a borosilicate glass wafer, which forms the first end region, and fixed by laser sintering. The proportion of glass particles XG decreases with the distance from the glass wafer, ie:

X _GI = 1 - Zi / h, where X _G i is the proportion of the glass particles in the i-th layer, z, the distance of the i-th layer from the glass wafer and h is the height of the transition region, and wherein for the proportion of Metal particles Χ _Μ , in the i-th layer of the transition region: XM _I = 1 - XGI- The transition region may be followed by one or more layers containing only metal particles to form the second end region.

The wafer prepared in this way can then be joined, for example by means of anodic bonding, with a silicon wafer containing the sensor bodies.

Subsequently, the sensor bodies are separated with adjoining balancing body, wherein the second end portion of the balancing body can then be joined with an intermediate body or a supporting body.

The invention will now be described with reference to the drawings

Embodiments explained.

It shows: schematically in longitudinal section a first embodiment of a measuring device according to the invention with a compensating body according to the invention; schematically in longitudinal section a second embodiment of a measuring device according to the invention with a compensating body according to the invention; and a schematic longitudinal section through an embodiment of a compensating body of a measuring device according to the invention. The compensating body 1 shown in FIG. 3 has an annular structure. It has a first end region 11 made of a ceramic material and / or glass, for example silicon carbide or silicon nitride and / or borosilicate glass, a transition region 12 and a second end region made of a metallic material, in particular steel. The transition region 12 has a

Composition, which changes in layers from a first inner boundary surface, which faces the first end portion 1 1, and which has the axial coordinate z = 0, to a second inner boundary surface, which faces the second end portion 13, and the axial Coordinate z = h, where h is the height of the transition region.

The composition of a layer with the mean axial coordinate z is XG ⁺ XM = 1 where XG (Z) = 1 -z / h and XM (Z) = z / h, where X _{G is} the glass component and XM is the component denote the metallic component.

The components are provided in particular in the form of microscale granules or powders, preferably with a particle size of not more than 20 μm and more preferably not more than 10 μm. For preparing a layer, the coordinate-dependent mixture of

Granules are applied to the already solidified layers and solidified by laser sintering, as described in the IMW Industry Communication No. 29 (2004) by Trenke entitled "Selective laser sintering of metallic / ceramic layer structures" or "Selective laser sintering of ceramic microcomponents", micro production 04 / 08, pp. 36-39.

The compensating body has, for example, a diameter of 4 mm. With a difference between the thermal expansion coefficients of the metallic material and the ceramic material of about 10 ppm / K and a height h = 0.25 mm, a value for the deformation parameter of d / h × Δα = 160 ppm / K follows. This value is in the middle range for the above requirements.

If the transition region is formed by N layers of the same layer thickness s = h / N, then d / sx Δα ₅ = 160 ppm / K applies correspondingly. The number N of layers may be, for example, 10 to 20.

One or both end regions of the compensation body can also be in

Lasersinterverfahren be prepared. On the other hand, an end region that after Another method is prepared as a substrate for the layered

Preparation of the transition region are prepared, the other

Either by continuing the laser sintering process with the composition of the end region, or can be provided as an independently manufactured body which is provided with an end face of the

Transition area is to add. Finally, both end regions can each serve as a substrate for the preparation of a part of the transition region, wherein subsequently the two parts of the transition region are joined together. It is currently preferred to use a glass wafer, in particular a borosilicate glass wafer, which forms a first end region of the compensation body as a substrate for the preparation of the layers of the transition region and the second end region. After the preparation of the layers, the glass wafer can be joined to a silicon wafer containing a plurality of sensor bodies, for example by anodic bonding. After joining the glass wafer with the silicon wafer, the semiconductor sensors are already attached

Balancing body isolated. The second end regions of the compensation body can then be joined in each case with a support body, for example by soldering, in particular brazing, or welding.

In Fig. 1 is a first embodiment of an inventive

Pressure gauge 100, which has a compensation body 1 10 for supporting a semiconductor sensor body 120 in a steel housing 130. The compensation body 1 10 includes a first end portion 1 1 1, which a

Borosilicate glass, such as Pyrex, has a transition region 1 12 and a second end portion 1 13, which has substantially sintered steel particles, wherein the transition region is a monotonously changing

Mixing ratio between glass and steel particles, wherein at the interface to the first end exclusively or almost exclusively

Glass particles and at the interface to the second edge region exclusively or almost exclusively steel particles exist. The transition region 12 comprises, for example, 20 layers of the same layer thickness, whereby the glass content X _G i of the layer decreases uniformly, ie: XGI + I = XGI - 0.05.

By means of the compensation body, a central compensation body channel 14 extends from an outer surface of the first end region 11 to an outer surface of the second end region 11. The semiconductor sensor body 120 includes a transducer element 121, and a pedestal 122, wherein the transducer element 121 and the pedestal 122 comprise monocrystalline silicon and are joined together with parallel-oriented crystal axes. The transducer element 121 comprises a measuring membrane 123 prepared by anisotropic etching, which piezoresistive not shown here

Having resistive elements in a Wheatstone bridge circuit to convert a pressure-dependent deformation of the measuring membrane into an electrical signal. Through the base 122 extends a central base channel 124, which is aligned with the compensation body channel 1 14 and communicates to supply a pressure formed between the base 122 and the measuring diaphragm 123 pressure chamber.

The steel housing 130 comprises a support body 131 made of steel, which may be designed as a so-called T08 socket, which has not shown here electrical feedthroughs for contacting the transducer element 121. Details for contacting the resistance elements via electrical feedthroughs through a support body 131 are known to a person skilled in the art and can be found, for example, in US Pat. No. 5,551,303. The second end portion 1 13 of the compensation body 1 10 has a

Thermal expansion coefficient, which is adapted to the thermal expansion coefficient of the support body 131. This makes it possible to add the second end region 1 13 of the compensating body 1 10 to the supporting body 131 by means of a brazed joint, because due to the adapted coefficients of thermal expansion, this is also the case with temperature fluctuations in measuring operation in the end region

Brazing hardly expect thermo-mechanical stresses that could affect the accuracy of the transducer element.

The housing 130 further comprises a housing body 132, in the interior of which a sensor chamber 134 is formed. The semiconductor sensor body 120 is arranged in the sensor chamber 134 and is held there by the support body 131 and the compensation body 1 10 in position, wherein the support body 131 is joined to the housing body 132, in particular welded, to close the sensor chamber 134 pressure-tight along this joint. The housing body 132 further has a first housing channel 136 which extends from a surface of the housing body 132 facing away from the support body 131 into the housing body 132

Sensor chamber 134 extends to a pressure chamber 125 facing away from the front side of the measuring diaphragm 123 to be able to act with a media pressure. Of the Support body 131 has a support body channel 138, which with the

Compensating body channel 1 14 communicates and is connected in a pressure-tight manner, so that a rear side of the measuring diaphragm 123 facing the pressure chamber 125 can be acted upon by the supporting body channel 14 with a second medium pressure or a reference pressure.

In Fig. 2 is a second embodiment of an inventive

Pressure gauge 200 having a balancing body 210 for supporting a semiconductor sensor body 220 in a steel housing 230. The essential difference between the exemplary embodiments is that in the second exemplary embodiment, an intermediate body 240 in the form of a Kovar tube is arranged between the compensation body 210 and a steel support body 231.

The balancing body 210 comprises a first end portion 21 1 comprising a borosilicate glass, such as Pyrex, a transition region 212 and a second end region 213, which comprises substantially sintered steel particles, the transition region being a monotonically varying one

Mixing ratio between glass and Kovar particles having at the interface to the first end exclusively or almost exclusively glass particles and at the interface to the second edge region exclusively or almost exclusively Kovarpartikel present. The transition region 212 comprises, for example, 15 layers of the same layer thickness, wherein the glass content X _G i of the layer decreases uniformly, ie: XGI ₊ I = XGI - 0.066, or 10 layers of the same layer thickness, whereby the glass content X _G i of the layer decreases uniformly, thus: X _{GI +} = X _G i - 0.1. Insofar as the difference between the

The coefficient of thermal expansion of Kovar and borosilicate glass is less than that between the coefficients of thermal expansion of steel and borosilicate glass, sufficient in the second embodiment, fewer layers than the first embodiment to reduce the thermal expansion difference.

The balancing body extends a central balancing body channel 214 from an outer surface of the first end portion 21 1 to an outer surface of the second end portion 213. The semiconductor sensor body 220 includes a transducer element 221, and a pedestal 222, wherein the transducer element 221 and the pedestal 222 are monocrystalline silicon have and are joined together with parallel oriented crystal axes. The transducer element 221 comprises a prepared by anisotropic etching Measuring diaphragm 223, which piezoresistive not shown here

Having resistive elements in a Wheatstone bridge circuit to convert a pressure-dependent deformation of the measuring membrane into an electrical signal. Through the base 222 extends a central base channel 224 which aligns with and communicates with the balancing body channel 214 to supply pressure to a pressure chamber formed between the base 222 and the measuring diaphragm 223.

The steel housing 230 comprises a support body 231 made of steel, which may be designed as a so-called T08 socket, which has not shown here electrical feedthroughs for contacting the transducer element 221.

The support body carries an intermediate body 240, which comprises a tube made of Kovar. The intermediate body 240 is inserted into a central bore 238 of the support body 231. The intermediate body 240 is connected to the support body 231 by

Welding or brazing pressure-tight along a circumferential joint.

The second end region 213 of the compensating body 210 has a coefficient of thermal expansion due to its composition of Kovar particles, which is adapted to the coefficient of thermal expansion of the formed as Kovar tube intermediate body 240. This allows the second end portion 213 of the balance body 210 to be brazed to the support body 231 without sacrificing the measurement characteristics of the transducer element

affecting thermomechanical stresses.

The steel housing 230 further comprises a housing body 232, in the interior of which a sensor chamber 234 is formed. The semiconductor sensor body 220 is arranged in the sensor chamber 234 and is held there by the support body 231, the intermediate body 240 and the compensation body 210 in position, the support body 231 is joined to the housing body 232, in particular welded, pressure-tight around the sensor chamber 234 along this joint to close. The housing body 232 furthermore has a first housing channel 236, which extends from a surface of the housing body 232 facing away from the support body 231 into the sensor chamber 234 in order to be able to pressurize a front side of the measuring diaphragm 223 facing away from the pressure chamber 225.

Through the tubular intermediate body 240 and thus communicating compensating body channel 214 is a pressure chamber 225 facing the back Measuring membrane 223 by the with a second media pressure or a

Reference pressure acted upon.

As a result, in both exemplary embodiments, a transducer element is mechanically coupled to metallic bodies via a compensating body, wherein

Thermal expansion differences between the transducer element and the metallic body can be reduced via the compensation body. In the entire coupling path can be dispensed with organic materials.

The common metallic material in the process industries is steel, especially stainless steel. As shown in the first embodiment, the

Thermal expansion difference between a transducer element made of silicon and a support body made of stainless steel are completely degraded by a compensation body. Alternatively, as explained with reference to the second exemplary embodiment, between the compensation body and a stainless steel housing, an intermediate body can still be used whose coefficient of thermal expansion matches the end region of the compensation body facing it, but which still has a different thermal expansion coefficient than that of the stainless steel housing. In this case, the connection between the stainless steel housing and the intermediate body is a source of thermo-mechanical stresses to be dissipated over a distance between the stainless steel housing and the balancing body.

Claims

claims

A measuring device (100; 200) comprising: a semiconductor sensor comprising a sensor body (120; 220) of a semiconductor material, in particular Si; a metallic support body (131; 231); and at least one intermediate body (110; 210; 240); wherein the sensor body via the at least one intermediate body (1 10; 210; 240), which between the sensor body (1 10; 220) and the

Support body (131, 231) is arranged, with the supporting body pressure-bearing mechanically connected, wherein at least one intermediate body (1 10, 210) as a balancing body (1 10, 210) is formed, wherein the balancing body comprises: a first end portion (1 1 1 21 1) having a first material having a first effective thermal expansion coefficient αι, a second end region (1 13; 213) having a second material with a second effective thermal expansion coefficient a ₂ , a transition region (1 12; 212) between the first end region (1 1 1; 21 1) and the second end region (1 13; 213), in which the effective thermal expansion coefficient of the first effective

Thermal expansion coefficient for the second effective

Coefficient of thermal expansion changes, wherein the transition region comprises a series of layers with a mixture of at least the first material and the second material, wherein the mixing ratio of the layers varies to a stepwise, in particular monotonous,

To achieve change in the coefficient of thermal expansion, wherein the first end region (1 1 1; 21 1) of the compensation body faces the sensor body (1 10; 210) and the second end region (1 13; 213) of the compensation body faces the support body (131; 231), wherein the first effective thermal expansion coefficient of the first

End region of the compensation body of the

Coefficient of thermal expansion of a material of a body adjoining the first end region of the compensating body does not deviate by more than 2 ppm / K, in particular not more than 1 ppm / K, the second effective thermal expansion coefficient of the second end region of the compensating body being substantially equal to

Coefficient of thermal expansion of a body adjacent to the second end region of the compensating body (1 10; 210) does not deviate by more than 2 ppm / K, in particular not more than 1 ppm / K, and wherein the second effective thermal expansion coefficient is greater than the first effective thermal expansion coefficient.

A measuring device according to claim 1, wherein the first end portion of the

Equalizing body comprises a glass, in particular a borosilicate glass.

Measuring device according to one of the preceding claims, wherein the first end region of the compensating body is joined to the sensor body pressure-tight, in particular by anodic bonding.

Measuring device according to one of the preceding claims, wherein the second end region of the compensating body is joined to the adjacent body pressure-tight, in particular by soldering, brazing or welding.

A meter according to claim 4, wherein the second end portion is joined to the support body.

Measuring device according to claim 4, wherein the second end portion is joined to a second intermediate body, which is arranged between the support body and the compensation body, wherein the second intermediate body in particular Kovar comprises. Measuring device according to one of the preceding claims, wherein the

Supporting body comprises steel.

Measuring device according to one of the preceding claims,

wherein the layers of the transition region of the compensation body i

Essentially parallel to each other.

Measuring device according to one of the preceding claims,

wherein the transition region of the compensation body perpendicular to a direction of the layer sequence has a maximum extent d, and wherein the transition region in the direction of the layer sequences has a height h, wherein:

where Δα is the difference between the first effective

Thermal expansion coefficient and the second

Thermal expansion coefficient is, and where ξ is a constant with the

Dimension 1 / K, for which applies: ξ <0.1% / K, in particular <500 ppm / K, preferably <250 ppm / K, more preferably <125 ppm / K and particularly preferably <60 ppm / K.

10. Measuring device according to claim 9, wherein the following applies:

where ΔΤ = (T _max -T _min ), the size of a specified

Operating temperature range for the measuring device, and where C is a dimensionless deformation parameter, for which applies: C <4%,

in particular C <2% and preferably C <1%.

Measuring device according to one of the preceding claims, wherein the

Transition region perpendicular to a direction of the layer sequence has a maximum extent d, and wherein a layer has a mean layer height s, where:

the

s

where Δα _{δ is} the difference of the effective thermal expansion coefficients of the layers adjacent to this layer. Thermal expansion coefficient is, and where ξ is a constant with the

Measuring device according to claim 1 1, wherein the following applies:

where ΔΤ = (T _max -T _min ), the size of a specified

Operating temperature range for the measuring device, and wherein C _{s is a} dimensionless deformation parameter, for which applies: Cs <4%, in particular <2% and preferably <1%.

Measuring device according to one of the preceding claims, wherein the first material is a ceramic material or a glass, and a

Has thermal expansion coefficient of not more than 5 ppm / K, especially not more than 4 ppm / K, and wherein the second material is a metallic material having a coefficient of thermal expansion of not less than 10 ppm / K, in particular not less than 13 ppm / K and further not less than 15 ppm / K.

Measuring device according to one of the preceding claims, wherein the layers in the transition region each have a layer height h of not less than 10 μιτι, in particular not less than 20 μιη and preferably not less than 40 μιη, and wherein the layers in the transition region in each case a layer height h of not more than 400 μιη, in particular not more than 200 μιτι and preferably not more than 100 μιη have.

Measuring device according to one of the preceding claims, wherein the

Transition region N layers each having a different effective thermal expansion coefficient, the value between the first coefficient of thermal expansion αι and the second

Coefficient of thermal expansion a ₂ , the number N being not less than (Δα) / (2 ppm / K), in particular not less than (Δα) / (1 ppm / K) and preferably not less than (2Δα) / (1 ppm / K) is. Measuring device according to one of the preceding claims, wherein the first and / or the second end region has a height which is at least half the height of the transition region, in particular not less than the height of the transition region and preferably not less than twice the height of the transition region is.

Measuring device according to one of the preceding claims, wherein the

Meter a pressure gauge, a density meter, a

Viscosity meter is a flow meter or a potentiometrischi meter.