Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
  • G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
  • G01L9/06—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of piezo-resistive devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
  • G01L19/14—Housings
  • G01L19/147—Details about the mounting of the sensor to support or covering means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
  • G01L19/0007—Fluidic connecting means
  • G01L19/0038—Fluidic connecting means being part of the housing
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
  • G01L19/0007—Fluidic connecting means
  • G01L19/0046—Fluidic connecting means using isolation membranes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
  • H01L2224/42—Wire connectors; Manufacturing methods related thereto
  • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
  • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
  • H01L2224/4805—Shape
  • H01L2224/4809—Loop shape
  • H01L2224/48091—Arched
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
  • H01L2224/732—Location after the connecting process
  • H01L2224/73251—Location after the connecting process on different surfaces
  • H01L2224/73265—Layer and wire connectors

Definitions

• the invention relates to a pressure sensor with a closed chip cavity comprising a piezoresistive sensor chip element for measuring the pressure of a chip flushing the print medium with an element bottom, and a carrier with a carrier top, on which the sensor chip element is attached to its underside, wherein this underside consists of an adhesive area and has an outer edge, and wherein the underside adheres to the carrier top in the adhesion area.
• Piezoresistive pressure sensors differ from others, in particular from piezoelectric pressure sensors in that they can reliably measure pressures over very long periods. Piezoelectric pressure sensors each need a "reset” to be ready for new measurements as they lose charge and "drift” over time.
• absolute pressure sensors are piezoresistive sensors, in particular oil-filled piezoresistive pressure sensors. They include a sensor chip element which is mounted on a support or on a bushing. As a rule, this is glued on with an adhesive. The sensor chip element is finally bathed under a membrane of oil. When pressure is applied outside the membrane, the oil under the membrane is also pressurized. The sensor chip generates a corresponding signal under pressure, which finally by two or more contacts with
• the pressure acts equally on the surface of the carrier or the bushing, on the center of the sensor chip element is mounted.
• the implementation bends slightly through, so that the center under the sensor chip element creates a slight depression.
• the adhesive creeps inwards between the bushing and the sensor chip element after some time to fill this well.
• the adhesive can be compressed by the pressure in the edge region of the sensor chip element and the carrier, as a result of which the sensor chip element is deformed. This upsetting evens out by creeping the adhesive after some time. This leads to a sig- nal drift, because the conditions of the back pressure change from below to the sensor chip element with time.
• the aforementioned problem of signal drift is thus not resolved, the sensor chip elements can also be compressed in this application. Even with the use of pasty adhesives that have little capillary action, the assembly is difficult. The pressure with which the sensor chip element 2 is attached to the adhesive can not be completely controlled. The adhesive is therefore squashed uncontrollably under the element 2, without it being possible to determine how far the adhesion region penetrates against the center of the element 5.
• differential pressure sensors are also known.
• the chip cavity of the differential pressure sensors is not closed but in pressure communication with a second pressure medium. Since the element determines the differential pressure between the ambient pressure and the cavity pressure, the carrier itself experiences no load.
• JP 61-226627 The element is fixed with clamps, which fix it by a spring force. Since no adhesive is used, no compression of the element can take place.
• the object of the invention is therefore to describe a novel attachment for the sensor chip element in a piezoresistive pressure sensor of the type described above, which has no signal drift result and which does not burden the contacts in shocks additionally.
• the dependent claims relate to particularly advantageous embodiments of the invention.
• the invention thus relates to a pressure sensor of the type described above, wherein the element underside has a non-adhesive region, and wherein the underside does not adhere to the carrier top surface in the non-adhesive region.
• the non-adhesive region extends at least over a circular area arranged centrally on the underside, which comprises one third of the total area of the element underside.
• the non-adhesive region comprises at least one connecting region from this central surface to the edge of the underside.
• the support of the pressure sensor has a depression in the center under the sensor chip element.
• a recess can be easily mounted as a bore. This ensures that the adhesive area comprises at most the region of the carrier top that is not arranged opposite this depression.
• the non-adhesive region accordingly comprises at least the region of the depression which lies opposite the element underside. It then forms at least the common area of depression and element sub-area.
• the adhesive can not spread through the capillary action on the central region of the underside of the sensor chip element, because the recessed area there is too large a distance from the carrier top.
• the depression should extend at least over a circular surface arranged centrally on the underside, which comprises one third of the total area of the element underside.
• the recess should at least form a connection region from the circular surface beyond the edge of the underside, so that the pressure in the pressure medium can spread through the connection region into a space below the non-adhesion region on the element underside.
• the pressure can act on all sides against the sensor chip element, even from below.
• the decisive factor is that the adhesion area is not in the middle region of the sensor chip element. It has been found that a central connection between the carrier and the sensor chip element can result in a deformation of the sensor chip element when the carrier bends itself under the high load of an applied pressure. Such deformation is not a problem in itself, as it also acts in the calibration of the pressure sensor.
• the middle connection loses its elasticity, as the adhesion usually declines slowly.
• the sensor chip element slowly deforms back into its original shape, which is in the data output of the measuring element falsely expressed as a pressure change.
• An attachment of the sensor chip element to the carrier according to the invention allows the sensor chip element to always retain its original shape and not be deformed by a deformation of the top side of the carrier itself.
• the adhesion area which is less than two thirds, preferably less than one third of the entire bottom surface of the sensor chip element, is located at the edge of this element. This is the least affected by the deflection of the carrier and therefore does not contribute to a deflection of the sensor chip element.
• the space between the non-adhesive region of the sensor chip element and the carrier is in pressure communication with the pressure chamber through the connection region and always results in a constant force on the underside of the sensor chip element.
• FIG. 1 shows an oil-filled piezoresistive pressure sensor according to the prior art, in cross-section
• Fig. 2 is a sensor chip element on a support with a
• a sensor chip adhesive according to the invention on the underside of a sensor chip element; an alternative sensor chip adhesive according to the invention on the underside of a sensor chip element; Another alternative sensor chip adhesive according to the invention on the underside of a sensor chip element; a sensor chip element on a support with a sensor chip adhesive according to the invention under pressure; a perspective view of a carrier with indication of the inventive sensor chip adhesive; a pressure sensor according to the invention.
• Fig. 1 shows a schematic representation of a pressure sensor 1 according to the prior art.
• a piezoresistive sensor chip element 2 which is mounted with its element bottom 5 on a support 6.
• the sensor chip element 2 comprises a piezoresistive chip 3 on a block-shaped chip base. 4.
• a chip cavity 27 is enclosed between this chip 3 and the base 4.
• the chip 3 measures the pressure difference between the reference pressure in the chip cavity 27 and the pressure acting on the chip 3 from the outside.
• the sensor chip element 2 is surrounded by a pressure medium 14 from all sides, except for its underside 5, and generates a measurement signal when pressure is applied, which is passed on through contacts 25. These run through the carrier 6, which is designed here as a passage.
• An insulation 11 ensures the sealing of the pressure chamber with the pressure medium 14.
• the measuring signals are finally further processed in an evaluation unit (not shown here).
• the housing 1 is closed with a membrane 13 against the pressure chamber 26.
• the contacts 25 and the sensor chip element 2 are protected against mechanical and chemical influences from the pressure chamber 26.
• the space around the sensor chip element 2 in these embodiments is usually filled with the pressure medium 14 oil, which always has the same pressure through the soft membrane 13 as the pressure chamber 26.
• Other, equivalent embodiments have no membrane 13 from.
• the sensor chip element 2 is exposed directly to the pressure medium 14 of the pressure chamber 26.
• the sensor chip element 2 has an element bottom 5, which is located on the chip pad 4 with respect to the chip 3. With this element bottom 5, it is mounted on the surface 7 of the carrier 6, which is directed against the pressure chamber 26.
• the adhesion region 8, with which the sensor chip element 2 adheres to the carrier 6, comprises the entire surface of the Element bottom 5.
• an adhesive 24 is used for the adhesion.
• FIG. 2 shows a known sensor chip element 2 according to FIG. 1 on a carrier 6 in cross section.
• the adhesive 24 is uniformly applied between the element bottom and the carrier surface. This figure 2 corresponds to an arrangement without pressurization.
• Figs. 3a and 3b show the same sensor chip element 2 of Fig. 2 under compressive loading at the time of pressurization (Fig. 3a) and long time later (Fig. 3b). Since this invention is a long-term pressure sensor that can reliably measure many months or years without requiring a "reset", the time between them may be correspondingly long.
• the carrier 6 is deflected by the compressive load, resulting in a curvature of the carrier top 7.
• the pressure load is on the bottom of the element 5 centered lower, because the adhesive 24 pulls this area towards the carrier top side 7. Therefore, the sensor chip element is slightly deformed, resulting in a slight increase in the measured value, which is detected by the chip 3. A dashed line on this shows exaggerated deflection.
• the pressure also acts laterally on the adhesive 24. Together with the negative pressure, which is formed centrally under the element bottom 5, the adhesive 24 creeps slowly over time towards the center, as shown in Fig. 3b. The pressure on the element bottom 5 changes as a result, and thus also the measuring signal, at constant pressure.
• the sensor chip element 2 relaxes and returns to its shape, which it had without pressure impact in Fig. 3.
• the arrows of the same length along a cross section of the sensor chip element indicate this accordingly.
• the element underside 5 does not adhere completely to the carrier 6 but only in a region which excludes the central region.
• an element bottom 5 is indicated with an outer edge 10. This element bottom 5 within the edge 10 is divided into a striped marked adhesion area 8 and an unmarked non-stick area 9. While the element bottom 5 may not adhere to the carrier 6 in the entire non-adhesive region 9, it does not necessarily have to adhere to the carrier 6 in the entire adhesion region. Adhesion has to be done within the detention area 8, but does not have to cover it completely.
• the carrier 6 has a depression 20 in the center. This ensures that the non-adhesive area 9 does not fill with adhesive during capillary assembly. Excess adhesive, which was at most applied too much, can flow into the depression 20, but without causing adhesion in the non-adhesion region 9.
• the non-adhesion region 9 comprises at least one third, preferably at least half, of the element underside 5, which defines a centrally arranged circular surface 15.
• the non-adhesion region 9 comprises at least one connection region 16 from this circular surface 15 to the edge 10 of the element bottom 5. This ensures that the pressure in the pressure medium 14 through the connection region 16 in the non-adhesive region 9, in particular in the space at the center Circular surface 15 on the element bottom 5 can spread.
• FIG. 5 shows a section of a sensor chip element 2 according to the invention under pressure load.
• the curvature of the carrier 6 is greatly exaggerated. Since the adhesive areas 8 are located only in the vicinity of the edge 10 and omit the central area, and in addition since the pressure also from the inside, i. From the center act on the compounds in the adhesion region 8, hardly affect forces on the sensor chip element 2, whereby this is hardly deformed. Accordingly, these negligible forces are hardly different even after a long time than at the beginning of the pressurization, whereby the measurement signal does not change even after a long time.
• the non-adhesive region 9 extends over a circular surface 15 arranged centrally on the element underside 5 and which comprises at least one third of the total area of the element underside 5. This ensures that, in the case of a deflection of the carrier upper side 7, scarcely more forces are transmitted to the sensor chip element 2 via the adhesion region 8. It is also important that the pressure medium 14 has at least one access through a connecting region 16 to the centrally arranged circular surface 15, so that the pressure can act on all sides.
• FIG. 4 b shows a further arrangement according to the invention of the adhesion region 8.
• the adhesive 24 is intended to be mounted substantially on a circular line 18, which runs concentrically to a sensor axis 17.
• the adhesion region 8 preferably consists of discrete points or discrete route sections, so that at least one connection to the non-adhesion region 9 is always ensured.
• the adhesion region 8 is advantageous to attach the adhesion region 8 to corner points 19 of the element bottom 5, as shown in FIGS. 4b and 4c.
• the adhesion region 8 should comprise less than 20%, preferably less than 5%, of the element bottom 5 as a whole. It has been found that this is completely sufficient to produce a sufficient adhesion between carrier 6 and sensor chip element 2.
• the inventive pressure sensor 1 for applications was aligned with very high pressures, in particular pressures above 50 bar. Typical applications include oceanography, oil and gas production, and gas transportation. However, it has been shown that even pressure sensors in the range of 1-5 bar already achieve significant improvements when the pressure sensor 1 according to the invention is designed. Particularly advantageous is the inventive pressure sensor 1, when the recess 20 is circular centrally formed under the generally rectangular sensor chip element, as shown in perspective in Fig. 6. Such a recess 20 can be easily mounted as a bore. According to the invention, here the diameter 21 of the recess 20 is greater than an edge length 22 and smaller than a diagonal 23 of the rectangular element underside 5. This ensures that there is always a connection region 16 which produces a pressure connection to the non-adhesion region 9, as is apparent from Fig. 4c and Fig. 5.
• the non-adhesive region 9 is therefore the common surface of the round recess 20 and the rectangular element lower surface 5. This is shown in Fig. 4c.
• the adhesion region extends over the corners 19 of the rectangular element lower surface 5 which lie outside the bore 20.
• a suitable adhesive 24 may be applied flat or punctiform on the element bottom surface 5 or on the carrier, before the sensor chip element 2 is placed on the Tröger 6. Thanks to the recess 20 of the required non-stick area and access of the print medium 14 to the sensor chip element underside 5 is always guaranteed.
• the sensor chip element 2 adheres to the carrier 6 by an adhesive 24.
• An adhesive 24 constitutes a medium which adheres to both surfaces. Soft, elastic adhesives have been found to give 24 better results than hard adhesives. In particular, adhesives 24 having a yield elongation of at least 100%, preferably 200%, transmit fewer forces and are therefore preferable to other adhesives 24. This is because the adhesive layers are usually applied very thinly. Tangential shifts are therefore possible even with thin layers.
• FIG. 7 shows a pressure sensor 1 according to the invention with a depression 20, for example along a diagonal 23 of the sensor chip element 2 in accordance with FIG. Fig. 4c. As shown, it may be configured without membrane 13 or, as shown in FIG. 1, with membrane 13.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Measuring Fluid Pressure (AREA)
• Pressure Sensors (AREA)

Priority Applications (4)

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Cited By (5)

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• 2010
  • 2010-09-13 CH CH01462/10A patent/CH703737A1/de not_active Application Discontinuation
• 2011
  • 2011-08-29 WO PCT/CH2011/000196 patent/WO2012027853A1/de not_active Ceased
  • 2011-08-29 US US13/819,450 patent/US8567256B2/en active Active
  • 2011-08-29 CN CN201180042379.7A patent/CN103080718B/zh active Active
  • 2011-08-29 EP EP11751529.6A patent/EP2612125B1/de active Active
  • 2011-08-29 JP JP2013526291A patent/JP5715698B2/ja active Active

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