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WO1996003629A1 - Protective diaphragm for a silicon pressure sensor - Google Patents

Protective diaphragm for a silicon pressure sensor Download PDF

Info

Publication number
WO1996003629A1
WO1996003629A1 PCT/DE1995/000907 DE9500907W WO9603629A1 WO 1996003629 A1 WO1996003629 A1 WO 1996003629A1 DE 9500907 W DE9500907 W DE 9500907W WO 9603629 A1 WO9603629 A1 WO 9603629A1
Authority
WO
WIPO (PCT)
Prior art keywords
protective membrane
cover
membrane
silicon chip
pressure sensor
Prior art date
Application number
PCT/DE1995/000907
Other languages
German (de)
French (fr)
Inventor
Peter Bauer
Manfred Frimberger
Lorenz Pfau
Josef Dirmeyer
Günter EHRLER
Original Assignee
Siemens Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to JP8505349A priority Critical patent/JPH10503021A/en
Priority to KR1019970700391A priority patent/KR970705015A/en
Priority to EP95924852A priority patent/EP0771415A1/en
Publication of WO1996003629A1 publication Critical patent/WO1996003629A1/en

Links

Classifications

    • 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
    • G01L19/06—Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa
    • G01L19/0627—Protection against aggressive medium in general
    • G01L19/0645—Protection against aggressive medium in general using isolation membranes, specially adapted for protection
    • 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
    • G01L19/0061—Electrical connection means
    • G01L19/0084—Electrical connection means to the outside 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
    • G01L19/14—Housings
    • G01L19/142—Multiple part housings
    • G01L19/143—Two part housings
    • 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
    • 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

Definitions

  • the invention relates to a protective membrane for a silicon pressure sensor according to the preamble of patent claim 1.
  • connection wires of silicon pressure sensors such as Bond wires and connection areas such as Bond pads must be protected from environmental influences in order to ensure the functionality of silicon pressure sensors over a long period of time.
  • the document EP 0 059 488 A1 shows a stainless steel membrane arranged at a distance above a capacitive silicon pressure sensor.
  • the cavity between the silicon pressure sensor and the protective membrane is filled with silicone oil.
  • the mass of the silicon chip acting as a pressure sensor membrane is increased by the gel applied to the silicon chip, the oil as the transmission medium between the silicon chip and the protective membrane, or the protective membrane lying directly on the silicon chip.
  • the pressure sensor membrane is sluggish. As a result, the pressure sensor no longer only records pressure but also accelerations. If the pressure sensor is used in a vehicle, for example, it is subjected to accelerations, which are then incorporated into its output signal.
  • the object of the present invention is to create an inexpensive pressure sensor which is protected against environmental influences and which, in particular, has a low sensitivity to acceleration and a high sensitivity to pressure.
  • a protective membrane which is connected to a cover enclosing the silicon chip, is made of a weakly air-permeable and water-impermeable material and is arranged at a distance above the pressure-absorbing silicon chip, one through the membrane, the cover and the silicon chip formed closed cavity is filled with air.
  • the protective membrane protects the pressure sensor, its connection surfaces and its connection wires against environmental influences and prevents corrosion on these components.
  • the mass of the pressure sensor membrane is increased only slightly by the protective membrane according to the invention and its arrangement above the air-filled cavity, so that the pressure sensor is very responsive and almost only absorbs pressure fluctuations but not changes in acceleration.
  • the protective membrane has poor air permeability.
  • a pressure increase in the cavity caused by a temperature increase causes pressure equalization with the environment via the protective membrane.
  • the pressure equalization takes place in a large time interval - for example in the minute range - compared to the duration of significant pressure signals recorded. The recorded pressure signals are thus not weakened or falsified.
  • FIG. 1 shows a longitudinal section through a pressure sensor with a cover formed in one piece with the protective membrane
  • FIG. 2 shows a perspective illustration of a cover which is formed in one piece with the protective membrane
  • FIG. 3 shows a view of the cover according to FIG. 2 from below
  • FIG. 4 shows a longitudinal section through a cover formed in two pieces with the protective membrane
  • FIG. 5 shows a longitudinal section through a pressure sensor with cover and protective membrane built into a housing.
  • FIG. 1 shows a pressure sensor designed as a silicon chip 2 and arranged on a base plate 1.
  • the pressure sensor can work according to the piezoresistive, the piezoelectric, the capacitive or another principle.
  • the silicon chip 2 is connected to an evaluating control circuit via connecting wires 3 which are led out downward through the base plate 1.
  • the connecting wires 3 are guided in a known manner through glass tubes, not shown here, through the base plate, so that the leadthroughs are tight against the environment.
  • the connection wires 3 are connected above the silicon chip 2 via bond wires 4, schematically indicated, to bond pads 5 on the surface of the silicon chip 2.
  • the bond wires 4, the bond pads 5 and in particular the connection points between bond wires 4 and bond pads 5 are at risk of corrosion. Furthermore, the entire surface of the silicon chip 2 is at risk of corrosion, in particular if the sensor is used in a chemically aggressive environment such as, for example, an atmosphere with salt spray. The surface of the silicon chip 2 with the connection structures 4 and 5 is therefore shielded from the environment.
  • a cover 7 is placed on the silicon chip 2 according to FIG. 1 and encloses the silicon chip 2.
  • a protective membrane 8 made of a weakly air-permeable and water-impermeable material, preferably plastic, is connected to the cover 7.
  • the cover 7 is also preferably made of plastic.
  • the cover 7, the protective membrane 8 and the silicon chip 2 describe a cavity 6 which is filled with air and as a pressure-transmitting medium between the protective membrane 8 and
  • Silicon chip 2 is used.
  • a pressure equalization with the environment takes place via the weakly air-permeable protective membrane 8.
  • a pressure equalization between the cavity and the environment via the membrane can also be necessary if the pressure sensor is operated at different ambient pressures.
  • different ambient air pressures act on the vehicle depending on the height above sea level in which the vehicle is operated. Filling the cavity with a pressure-transmitting medium that has an almost temperature-independent expansion coefficient, such as oil is therefore superfluous.
  • a protective membrane made of elastic plastic, preferably silicone rubber, has these properties with a simultaneous water resistance to a particular degree.
  • a suitable silicone rubber is sold, for example, by Bayer (Leverkusen, DE) under the name "LSR".
  • the protective membrane 8 can, for example, also be made from a natural rubber or another elastomer which has the aforementioned properties.
  • Cover 7 and protective membrane 8 can, according to FIG. 1, be made in one piece from the same material - plastic, elastic plastic, elastomer, silicone rubber - for example by injection molding, or have two material components according to FIG.
  • cover 7 is made of a different material than the protective membrane 8, the cover 7 and the protective membrane 8 are sealingly connected to one another. Sealing lips 9 are preferably formed on the ends of the cover 7 and seal the cover 7 according to FIG. 5 against a housing enclosing an electronics module with the pressure sensor.
  • the protective membrane 8 preferably has a bead 10 in its outer peripheral part. If the pressure sensor is exposed to changing temperatures or changing ambient pressures, the protective membrane 8 can expand or contract within certain limits by means of the bead 10. Stresses in the protective membrane 8, which influence the sensitivity of the pressure sensor, are thus avoided. Furthermore, voltages in the protective membrane 8 that occur during their manufacture are compensated for.
  • the mobility 10 of the protective membrane 8 is also influenced by the bead 10. If, for example, the protective membrane 8 is thick, it nevertheless remains easily movable due to a thin bead area. If the protective membrane 8 has a bead, the protective membrane 8 has an almost constant restoring force over its entire deflection range.
  • the inertia and the damping behavior of the protective membrane 8 and thus also the sensitivity of the pressure sensor can be influenced by the thickness of the protective membrane 8, its material properties and the configuration of the bead 10.
  • the protective membrane 8 is preferably very soft in order to transmit a pressure wave to be recorded to the pressure sensor with as little loss as possible. If the cover 7 is also made of a very soft material, its handling causes difficulties during assembly. According to Figure 4, the cover 7 is therefore made of an easy-to-handle harder material, while the protective membrane 8 is made of a softer material.
  • FIG. 2 shows a perspective view of the cover 7 with the protective membrane 8 in one piece.
  • the inner circumference of the cover 7, with which the cover 7 is pushed onto the pressure sensor can be of a uniformly round shape or, according to FIG. 3, wavy.
  • FIG. 3 shows the cover 7 formed in one piece with the protective membrane 8 from below.
  • the waves 11 in the inner circumference 12 of the cover 7, when the cover 7 is attached to the pressure sensor cause small, semi-cylindrical cavities through which a superfluous air from the cavity 6 between the protective membrane 8 and the pressure sensor arises when the cover 7 is attached to the pressure sensor is discharged downwards.
  • the cavity 6 is also closed off next to the protective membrane 8, the cover 7 and the silicon chip 2 by a printed circuit board 13 carrying the silicon chip 2.
  • FIG. 5 shows a pressure sensor enclosed by a cover 7 with a protective membrane 8, which is mounted with its connecting wires 3 onto a printed circuit board 13.
  • a housing which has an upper wall 14 and a lower wall 15 encloses this arrangement.
  • In the upper wall 14 there is an opening 16 which connects the pressure sensor to the surroundings via a channel 17, so that the pressure fluctuations to be measured are channel 17 and the protective membrane 8 to the pressure sensor.
  • the channel 17 runs approximately parallel to the wall 14 of the housing. This prevents manual contact of the protective membrane 8 from the outside.
  • the cover 7 is fitted between the upper wall 14 and the printed circuit board 13 in such a way that it covers the silicon chip 2 in a sealing manner and at the same time encloses the opening 16 with its sealing lips 9 so that the opening 16 is completely sealed off from the rest of the housing interior.
  • the pressure sensor with the protective membrane according to the invention is preferably used for side impact detection in side parts of vehicles.

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

Abstract

The invention relates to a protective diaphragm for silicon pressure sensors to protect the silicon chip and its electrical connections against damaging environmental influences. The diaphragm has a bead on its outer periphery by means of which temperature and pressure stresses can be balanced and the inertia of the diaphragm can be influenced.

Description

Beschreibungdescription
Schutzmembran für einen SiliziumdrucksensorProtective membrane for a silicon pressure sensor
Die Erfindung betrifft eine Schutzmembran für einen Silizium¬ drucksensor gemäß Oberbegriff des Patentanspruchs 1.The invention relates to a protective membrane for a silicon pressure sensor according to the preamble of patent claim 1.
Insbesondere Anschlußdrähte von Siliziumdrucksensoren wie z.B. Bonddrähte sowie Anschlußflächen wie z.B. Bondpads müssen vor Umwelteinflüssen geschützt werden, um die Funk¬ tionstüchtigkeit von Siliziumdrucksensoren über einen langen Zeitraum zu gewährleisten.In particular connection wires of silicon pressure sensors such as Bond wires and connection areas such as Bond pads must be protected from environmental influences in order to ensure the functionality of silicon pressure sensors over a long period of time.
Die Druckschrift EP 0 059 488 AI zeigt eine in einem Abstand über einem kapazitiven Siliziumdrucksensor angeordnete Edel¬ stahlmembran. Der Hohlraum zwischen Siliziumdrucksensor und der Schutzmembran ist mit Silikonöl gefüllt.The document EP 0 059 488 A1 shows a stainless steel membrane arranged at a distance above a capacitive silicon pressure sensor. The cavity between the silicon pressure sensor and the protective membrane is filled with silicone oil.
Die Druckschrift US 4,843,454 offenbart eine Schutzmembran aus Aluminium oder Gummi, die auf einem piezoresistiven Siliziumdruckwandler aufliegt.The document US 4,843,454 discloses a protective membrane made of aluminum or rubber, which rests on a piezoresistive silicon pressure transducer.
Die Druckschrift US 3 088 323 offenbart einen Siliziumdruck¬ sensor, der mit einer Silikongelschicht bedeckt ist.The document US 3,088,323 discloses a silicon pressure sensor which is covered with a silicone gel layer.
Durch das auf den Siliziumchip aufgetragene Gel, das öl als Übertragungsmedium zwischen Siliziumchip und Schutzmembran, oder die direkt auf dem Siliziumchip aufliegende Schutzmem¬ bran wird die Masse des als Drucksensormembran wirkenden Siliziumchips erhöht. Die Drucksensormembran wird damit träger. Infolgedessen nimmt der Drucksensor nicht mehr nur Druck sondern auch Beschleunigungen auf. Wird der Drucksensor beispielsweise in einem Fahrzeug eingesetzt, ist er Beschleu¬ nigungen ausgesetzt, die dann in sein Ausgangssignal einge- hen. Aufgabe der vorliegenden Erfindung ist es, einen vor Umwelt¬ einflüssen geschützten, kostengünstigen Drucksensor zu schaf¬ fen, der insbesondere eine geringe Beschleunigungsempfind¬ lichkeit und dabei eine hohe Druckempfindlichkeit aufweist.The mass of the silicon chip acting as a pressure sensor membrane is increased by the gel applied to the silicon chip, the oil as the transmission medium between the silicon chip and the protective membrane, or the protective membrane lying directly on the silicon chip. The pressure sensor membrane is sluggish. As a result, the pressure sensor no longer only records pressure but also accelerations. If the pressure sensor is used in a vehicle, for example, it is subjected to accelerations, which are then incorporated into its output signal. The object of the present invention is to create an inexpensive pressure sensor which is protected against environmental influences and which, in particular, has a low sensitivity to acceleration and a high sensitivity to pressure.
Die Aufgabe wird gelöst durch die Merkmale des Patentan¬ spruchs 1.The object is achieved by the features of patent claim 1.
Eine Schutzmembran, die mit einer den Siliziumchip umschlie- ßenden Abdeckung verbunden ist, ist aus einem schwach luft¬ durchlässigen und wasserundurchlässigen Material hergestellt und in einem Abstand oberhalb des den Druck aufnehmenden Siliziumchips- angeordnet, wobei ein durch die Membran, die Abdeckung und den Siliziumchip gebildeter geschlossener Hohlraum mit Luft gefüllt ist.A protective membrane, which is connected to a cover enclosing the silicon chip, is made of a weakly air-permeable and water-impermeable material and is arranged at a distance above the pressure-absorbing silicon chip, one through the membrane, the cover and the silicon chip formed closed cavity is filled with air.
Die Schutzmembran schützt den Drucksensor, seine Anschlu߬ flächen und seine Anschlußdrähte vor Umwelteinflüssen und verhindert Korrosion an diesen Bauteilen. Die Masse der Drucksensormembran wird durch die erfindungsgemäße Schutzmem¬ bran und ihre Anordnung über dem mit Luft gefüllten Hohlraum nur geringfügig erhöht, sodaß der Drucksensor sehr reaktions¬ schnell ist und nahezu nur Druckschwankungen, nicht aber Beschleunigungsänderungen aufnimmt.The protective membrane protects the pressure sensor, its connection surfaces and its connection wires against environmental influences and prevents corrosion on these components. The mass of the pressure sensor membrane is increased only slightly by the protective membrane according to the invention and its arrangement above the air-filled cavity, so that the pressure sensor is very responsive and almost only absorbs pressure fluctuations but not changes in acceleration.
Die Schutzmembran weist eine schwache Luftdurchlässigkeit auf. Damit erfolgt bei einer z.B. durch eine Temperaturerhö¬ hung verursachten Druckerhöhung im Hohlraum ein Druckaus¬ gleich mit der Umgebung über die Schutzmembran. Der Druckaus- gleich erfolgt in einem großen Zeitintervall - etwa im Minu¬ tenbereich - verglichen mit der Dauer von aufgenommenen, signifikanten Drucksignalen. Damit werden die aufgenommenen Drucksignale nicht abgeschwächt oder verfälscht.The protective membrane has poor air permeability. With a e.g. a pressure increase in the cavity caused by a temperature increase causes pressure equalization with the environment via the protective membrane. The pressure equalization takes place in a large time interval - for example in the minute range - compared to the duration of significant pressure signals recorded. The recorded pressure signals are thus not weakened or falsified.
Vorteilhafte Weiterbildungen der Erfindung sind in den Unteransprüchen gekennzeichnet. Ausführungsbeispiele der Erfindung werden anhand der Zeich¬ nung erläutert. Es zeigenAdvantageous developments of the invention are characterized in the subclaims. Embodiments of the invention are explained with reference to the drawing. Show it
Figur 1 einen Längsschnitt durch einen Drucksensor mit einer mit der Schutzmembran einstückig ausgebildeten Ab¬ deckung,FIG. 1 shows a longitudinal section through a pressure sensor with a cover formed in one piece with the protective membrane,
Figur 2 eine perspektivische Darstellung einer einstückig mit der Schutzmembran ausgebildeten Abdeckung von oben,FIG. 2 shows a perspective illustration of a cover which is formed in one piece with the protective membrane,
Figur 3 eine Ansicht der Abdeckung gemäß Figur 2 von unten, Figur 4 einen Längsschnitt durch eine zweistückig mit der Schutzmembran ausgebildeten Abdeckung, und3 shows a view of the cover according to FIG. 2 from below, FIG. 4 shows a longitudinal section through a cover formed in two pieces with the protective membrane, and
Figur 5 einen Längsschnitt durch einen in ein Gehäuse einge¬ bauten Drucksensor mit Abdeckung und Schutzmembran.FIG. 5 shows a longitudinal section through a pressure sensor with cover and protective membrane built into a housing.
Figur 1 zeigt einen als Siliziumchip 2 ausgebildeten und auf einer Grundplatte 1 angeordneten Drucksensor. Der Drucksensor kann nach dem piezoresistiven, dem piezoelektrischen, dem kapazitiven oder einem anderen Prinzip arbeiten. Der Sili¬ ziumchip 2 ist über Anschlußdrähte 3, die nach unten durch die Grundplatte 1 herausgeführt sind, mit einer auswertenden Steuerschaltung verbunden. Die Anschlußdrähte 3 sind in bekannter Weise über hier nicht dargestellte Glasröhrchen durch die Grundplatte geführt, sodaß die Durchführungen dicht gegen die Umgebung sind. Die Anschlußdrähte 3 sind oberhalb des Siliziumchips 2 über schematisch angedeutete Bonddrähte 4 mit Bondpads 5 auf der Oberfläche des Siliziumchips 2 verbun¬ den.FIG. 1 shows a pressure sensor designed as a silicon chip 2 and arranged on a base plate 1. The pressure sensor can work according to the piezoresistive, the piezoelectric, the capacitive or another principle. The silicon chip 2 is connected to an evaluating control circuit via connecting wires 3 which are led out downward through the base plate 1. The connecting wires 3 are guided in a known manner through glass tubes, not shown here, through the base plate, so that the leadthroughs are tight against the environment. The connection wires 3 are connected above the silicon chip 2 via bond wires 4, schematically indicated, to bond pads 5 on the surface of the silicon chip 2.
Die Bonddrähte 4, die Bondpads 5 und insbesondere die Verbin- dungsstellen zwischen Bonddrähten 4 und Bondpads 5 sind korrosionsgefährdet. Ferner ist die gesamte Oberfläche des Siliziumchip 2 korrosionsgefährdet, insbesondere wenn der Sensor in einer chemisch aggressiven Umgebung wie beispiels¬ weise einer Atmosphäre mit Salznebeln eingesetzt wird. Die Oberfläche des Siliziumchip 2 mit den Anschlußstrukturen 4 und 5 wird deshalb gegen die Umgebung abgeschirmt. Eine Abdeckung 7 wird gemäß Figur 1 auf den Siliziumchip 2 aufgesetzt und umschließt den Siliziumchip 2. Eine Schutzmem¬ bran 8 aus einem schwach luftdurchlässigen und wasserundurch¬ lässigen Material, vorzugsweise Kunststoff, ist mit der Abdeckung 7 verbunden. Die Abdeckung 7 ist ebenfalls vorzugs¬ weise aus Kunsstoff hergestellt.The bond wires 4, the bond pads 5 and in particular the connection points between bond wires 4 and bond pads 5 are at risk of corrosion. Furthermore, the entire surface of the silicon chip 2 is at risk of corrosion, in particular if the sensor is used in a chemically aggressive environment such as, for example, an atmosphere with salt spray. The surface of the silicon chip 2 with the connection structures 4 and 5 is therefore shielded from the environment. A cover 7 is placed on the silicon chip 2 according to FIG. 1 and encloses the silicon chip 2. A protective membrane 8 made of a weakly air-permeable and water-impermeable material, preferably plastic, is connected to the cover 7. The cover 7 is also preferably made of plastic.
Die Abdeckung 7, die Schutzmembran 8 und der Siliziumchip 2 beschreiben einen Hohlraum 6, der mit Luft gefüllt ist und als druckübertragendes Medium zwischen Schutzmembran 8 undThe cover 7, the protective membrane 8 and the silicon chip 2 describe a cavity 6 which is filled with air and as a pressure-transmitting medium between the protective membrane 8 and
Siliziumchip 2 dient. Bei einer durch eine Temperaturerhöhung verursachten Druckerhöhung im Hohlraum 6 erfolgt ein Druck¬ ausgleich mit der Umgebung über die schwach luftdurchlässige Schutzmembran 8. Ein Druckausgleich zwischen Hohlraum und Umgebung über die Membran kann auch dann notwendig werden, wenn der Drucksensor bei unterschiedlichen Umgebungsdrücken betrieben wird. Bei einem beispielsweise in einem Fahrzeug angeordneten Drucksensor wirken je nach der Höhe über über dem Meeresspiegel, in der das Fahrzeug betrieben wird, unter- schiedliche Umgebungsluftdrücke auf das Fahrzeug. Eine Fül¬ lung des Hohlraums mit einem druckübertragenden Medium, das einen nahezu temperaturunabhängigen Ausdehnungskoeffizienten aufweist wie z.B. öl, ist damit überflüssig.Silicon chip 2 is used. In the event of a pressure increase in the cavity 6 caused by an increase in temperature, a pressure equalization with the environment takes place via the weakly air-permeable protective membrane 8. A pressure equalization between the cavity and the environment via the membrane can also be necessary if the pressure sensor is operated at different ambient pressures. In the case of a pressure sensor arranged, for example, in a vehicle, different ambient air pressures act on the vehicle depending on the height above sea level in which the vehicle is operated. Filling the cavity with a pressure-transmitting medium that has an almost temperature-independent expansion coefficient, such as oil is therefore superfluous.
Der Druckausgleich über die Membran erfolgt in einem großen Zeitintervall - etwa im Minutenbereich - verglichen mit der Dauer von aufgenommenen, signifikanten Drucksignalen. Damit werden die aufgenommenen Drucksignale nicht abgeschwächt oder verfälscht. Eine Schutzmembran aus elastischem Kunsstoff, vorzugsweise Silikongummi, weist diese Eigenschaften bei gleichzeitiger Wasserresistenz in besonderem Maße auf. Ein geeignetes Silikongummi wird beispielsweise von der Firma Bayer (Leverkusen, DE) unter der Bezeichnung "LSR" vertrie¬ ben. Die Schutzmembran 8 kann aber beispielsweise auch aus einem Naturkautschuk oder einem sonstigen Elastomer herge¬ stellt sein, der vorgenannte Eigenschaften aufweist. Abdeckung 7 und Schutzmembran 8 können gemäß Figur 1 ein¬ stückig aus demselben Material - Kunsstoff, elastischer Kunststoff, Elastomer, Silikongummi - beispielsweise im Spritzgußverfahren hergestellt werden, oder gemäß Figur 4 zwei Materialkomponenten aufweisen. Ist die Abdeckung 7 aus einem anderen Material als die Schutzmembran 8 hergestellt, so werden Abdeckung 7 und Schutzmembran 8 abdichtend miteinander verbunden. An den Abschlüssen der Abdeckung 7 sind vorzugsweise Dichtlippen 9 ausgeformt, die die Abdeckung 7 gemäß Figur 5 gegen ein eine Elektronikbaugruppe mit dem Drucksensor umschließendes Gehäuse abdichten.The pressure equalization across the membrane takes place in a large time interval - approximately in the minute range - compared to the duration of significant pressure signals recorded. The recorded pressure signals are thus not weakened or falsified. A protective membrane made of elastic plastic, preferably silicone rubber, has these properties with a simultaneous water resistance to a particular degree. A suitable silicone rubber is sold, for example, by Bayer (Leverkusen, DE) under the name "LSR". The protective membrane 8 can, for example, also be made from a natural rubber or another elastomer which has the aforementioned properties. Cover 7 and protective membrane 8 can, according to FIG. 1, be made in one piece from the same material - plastic, elastic plastic, elastomer, silicone rubber - for example by injection molding, or have two material components according to FIG. 4. If the cover 7 is made of a different material than the protective membrane 8, the cover 7 and the protective membrane 8 are sealingly connected to one another. Sealing lips 9 are preferably formed on the ends of the cover 7 and seal the cover 7 according to FIG. 5 against a housing enclosing an electronics module with the pressure sensor.
Die Schutzmembran 8 weist in ihrem äußeren Umfangsteil vor¬ zugsweise eine Sicke 10 auf. Ist der Drucksensor wechselnden Temperaturen oder wechselnden Umgebungsdrücken ausgesetzt, kann sich die Schutzmembran 8 mittels der Sicke 10 in gewis¬ sen Grenzen ausdehnen oder zusammenziehen. Damit werden Spannungen in der Schutzmembran 8 vermieden, die die Empfind¬ lichkeit des Drucksensors beeinflussen. Ferner werden Span- nungen in der Schutzmembran 8, die bei ihrer Herstellung auf¬ treten, ausgeglichen.The protective membrane 8 preferably has a bead 10 in its outer peripheral part. If the pressure sensor is exposed to changing temperatures or changing ambient pressures, the protective membrane 8 can expand or contract within certain limits by means of the bead 10. Stresses in the protective membrane 8, which influence the sensitivity of the pressure sensor, are thus avoided. Furthermore, voltages in the protective membrane 8 that occur during their manufacture are compensated for.
Durch die Sicke 10 wird auch die Beweglichkeit der Schutzmem¬ bran 8 beeinflußt. Ist die Schutzmembran 8 beispielsweise dick ausgebildet, so bleibt sie infolge eines dünnen Sicken- bereichs dennoch gut beweglich. Weist die Schutzmembran 8 eine Sicke auf, wirkt auf die Schutzmembran 8 eine nahezu konstante Rückstellkraft über ihren ganzen Auslenkungsbe¬ reich.The mobility 10 of the protective membrane 8 is also influenced by the bead 10. If, for example, the protective membrane 8 is thick, it nevertheless remains easily movable due to a thin bead area. If the protective membrane 8 has a bead, the protective membrane 8 has an almost constant restoring force over its entire deflection range.
Die Trägheit und das Dämpfungsverhalten der Schutzmembran 8 und damit auch die Empfindlichkeit des Drucksensors sind durch die Dicke der Schutzmembran 8, ihre Materialeigenschaf¬ ten sowie die Ausbildung der Sicke 10 beeinflußbar. Je härter und dicker die Schutzmembran 8 ist, desto stärker gedämpft ist sie. Mit zunehmender Dicke wird die Schutzmembran 8 träger. Ist die Schutzmembran 8 zu dick ausgebildet, reagiert sie nicht nur auf Druckänderungen, sondern auch auf Beschleu¬ nigungsänderungen.The inertia and the damping behavior of the protective membrane 8 and thus also the sensitivity of the pressure sensor can be influenced by the thickness of the protective membrane 8, its material properties and the configuration of the bead 10. The harder and thicker the protective membrane 8, the more damped it is. With increasing thickness, the protective membrane 8 becomes more sluggish. If the protective membrane 8 is too thick, it reacts not only on changes in pressure, but also on changes in acceleration.
Vorzugsweise ist die Schutzmembran 8 sehr weich ausgebildet, um eine aufzunehmende Druckwelle möglichst verlustfrei an den Drucksensor weiterzuleiten. Wird auch die Abdeckung 7 aus einem sehr weichen Material hergestellt, bereitet ihre Hand¬ habung bei der Montage Schwierigkeiten. Gemäß Figur 4 wird deshalb die Abdeckung 7 aus einem gut handhabbaren härteren Material gefertigt, während die Schutzmembran 8 aus einen weicheren Material hergestellt ist.The protective membrane 8 is preferably very soft in order to transmit a pressure wave to be recorded to the pressure sensor with as little loss as possible. If the cover 7 is also made of a very soft material, its handling causes difficulties during assembly. According to Figure 4, the cover 7 is therefore made of an easy-to-handle harder material, while the protective membrane 8 is made of a softer material.
Figur 2 zeigt eine perspektivische Ansicht der Abdeckung 7 mit der Schutzmembran 8 in einer einstückigen Ausbildung. Der innere Umfang der Abdeckung 7, mit dem die Abdeckung 7 auf den Drucksensor aufgeschoben wird, kann dabei gleichmäßig rund oder gemäß Figur 3 wellenförmig ausgebildet sein. Figur 3 zeigt dabei die einstückig mit der Schutzmembran 8 ausge¬ bildete Abdeckung 7 von unten. Die Wellen 11 im inneren Umfang 12 der Abdeckung 7 verursachen bei auf den Drucksensor aufgesteckter Abdeckung 7 kleine, halbzylindrische Hohlräume, durch die eine beim Aufstecken der Abdeckung 7 auf den Druck¬ sensor entstehende überflüssige Luft aus dem Hohlraum 6 zwischen der Schutzmembran 8 und dem Drucksensor nach unten abgeführt wird. Der Hohlraum 6 wird bei vollständig auf den Drucksensor aufgesteckter Abdeckung 7 neben der Schutzmembran 8, der Abdeckung 7 und dem Siliziumchip 2 ferner durch eine den Siliziumchip 2 tragende Leiterplatte 13 abgeschlossen.Figure 2 shows a perspective view of the cover 7 with the protective membrane 8 in one piece. The inner circumference of the cover 7, with which the cover 7 is pushed onto the pressure sensor, can be of a uniformly round shape or, according to FIG. 3, wavy. FIG. 3 shows the cover 7 formed in one piece with the protective membrane 8 from below. The waves 11 in the inner circumference 12 of the cover 7, when the cover 7 is attached to the pressure sensor, cause small, semi-cylindrical cavities through which a superfluous air from the cavity 6 between the protective membrane 8 and the pressure sensor arises when the cover 7 is attached to the pressure sensor is discharged downwards. When the cover 7 is completely attached to the pressure sensor, the cavity 6 is also closed off next to the protective membrane 8, the cover 7 and the silicon chip 2 by a printed circuit board 13 carrying the silicon chip 2.
Figur 5 zeigt einen von einer Abdeckung 7 mit einer Schutz¬ membran 8 umschlossenen Drucksensor, der mit seinen Anschlu߬ drähten 3 auf eine Leiterplatte 13 montiert ist. Ein Gehäuse, das eine obere Wandung 14 und eine untere Wandung 15 auf¬ weist, umschließt diese Anordnung. In der oberen Wandung 14 befindet sich ein Durchbruch 16, der über einen Kanal 17 den Drucksensor mit der Umgebung verbindet, sodaß die zu messen¬ den Druckschwankungen über den Kanal 17 und die Schutzmembran 8 zum Drucksensor geführt werden. Der Kanal 17 verläuft in etwa parallel zur Wandung 14 des Gehäuses. Dadurch wird eine manuelle Berührung der Schutzmembran 8 von außen verhindert. Die Abdeckung 7 ist derart zwichwn oberer Wandung 14 unnd Leiterplatte 13 eingepaßt, daß sie einerseits den Silizium¬ chip 2 abdichtend abdeckt und gleichzeitig den Durchbruch 16 mit ihren Dichtlippen 9 so umschließt, daß der Durchbruch 16 gegenüber dem übrigen Gehäuseinneren vollständig abgedichtet wird.FIG. 5 shows a pressure sensor enclosed by a cover 7 with a protective membrane 8, which is mounted with its connecting wires 3 onto a printed circuit board 13. A housing which has an upper wall 14 and a lower wall 15 encloses this arrangement. In the upper wall 14 there is an opening 16 which connects the pressure sensor to the surroundings via a channel 17, so that the pressure fluctuations to be measured are channel 17 and the protective membrane 8 to the pressure sensor. The channel 17 runs approximately parallel to the wall 14 of the housing. This prevents manual contact of the protective membrane 8 from the outside. The cover 7 is fitted between the upper wall 14 and the printed circuit board 13 in such a way that it covers the silicon chip 2 in a sealing manner and at the same time encloses the opening 16 with its sealing lips 9 so that the opening 16 is completely sealed off from the rest of the housing interior.
Der Drucksensor mit der erfindungsgemäßen Schutzmembran wird vorzugsweise zur Seitenaufprallerkennung in Seitenteilen von Fahrzeugen eingesetzt.The pressure sensor with the protective membrane according to the invention is preferably used for side impact detection in side parts of vehicles.
Die beschriebenen Eigenschaften von Silikonkautschuk wurden in Versuchsreihen nachgewiesen. The properties of silicone rubber described have been demonstrated in test series.

Claims

Patentansprüche Patent claims
1. Schutzmembran für Siliziumdrucksensoren, die in einem Abstand oberhalb eines den Druck aufnehmenden Siliziumchips (2) angeordnet und mit einer den Siliziumchip (2) umschließenden Abdeckung (7) verbunden ist, »dadurch gekenn¬ zeichnet, daß die Membran (8) aus einem schwach luftdurchläs¬ sigen und wasserundurchlässigen Material hergestellt ist, und daß durch die Membran (8), die Abdeckung (7) und den Siliziumchip (2) ein geschlossener Hohlraum (6) gebildet wird, der mit Luft gefüllt ist.1. Protective membrane for silicon pressure sensors, which is arranged at a distance above a pressure-receiving silicon chip (2) and is connected to a cover (7) surrounding the silicon chip (2), "characterized in that the membrane (8) consists of a slightly air-permeable and water-impermeable material is made, and that a closed cavity (6) which is filled with air is formed by the membrane (8), the cover (7) and the silicon chip (2).
2. Schutzmembran nach Anspruch 1, dadurch gekennzeichnet, daß die Membran (8) aus Kunststoff hergestellt ist.2. Protective membrane according to claim 1, characterized in that the membrane (8) is made of plastic.
3. Schutzmembran nach Anspruch 1, dadurch gekennzeichnet, daß die Membran (8) aus einem Elastomer hergestellt ist.3. Protective membrane according to claim 1, characterized in that the membrane (8) is made of an elastomer.
4. Schutzmembran nach Anspruch 1, dadurch gekennzeichnet, daß die Membran (8) aus Silikongummi hergestellt ist.4. Protective membrane according to claim 1, characterized in that the membrane (8) is made of silicone rubber.
5. Schutzmembran nach Anspruch 1, dadurch gekennzeichnet, daß die Schutzmembran (8) und die Abdeckung (7) aus demselben Material hergestellt und einstückig ausgebildet sind.5. Protective membrane according to claim 1, characterized in that the protective membrane (8) and the cover (7) are made of the same material and are formed in one piece.
6. Schutzmembran nach Anspruch 1, dadurch gekennzeichnet, daß die Abdeckung 6. Protective membrane according to claim 1, characterized in that the cover
(7) aus einem härteren Material als die Membran (8) hergestellt ist.(7) is made of a harder material than the membrane (8).
1 . Schutzmembran nach Anspruch 1, dadurch gekennzeichnet, daß die Membran (8) in ihrem äußeren Umfangsbereich eine Sicke (10) aufweist.1 . Protective membrane according to claim 1, characterized in that the membrane (8) has a bead (10) in its outer peripheral region.
8. Schutzmembran nach Anspruch 1 , dadurch gekennzeichnet, daß die Membran (8) im Bereich der Sicke (10) dünner ausgebildet ist als in ihren anderen Bereichen. 8. Protective membrane according to claim 1, characterized in that the membrane (8) is thinner in the area of the bead (10) than in its other areas.
9. Schutzmembran nach Anspruch 1, daurch gekennzeichnet, daß der innere Umfang (12) der Abdeckung (7) eine wellenförmige Struktur (11) aufweist und der Hohlraum (6) durch die Membran (8), die Abdeckung (7), den Siliziumchip (2) und eine den Siliziumchip (2) tragende Leiterplatte (13) beschrieben ist.9. Protective membrane according to claim 1, characterized in that the inner circumference (12) of the cover (7) has a wave-shaped structure (11) and the cavity (6) through the membrane (8), the cover (7), the silicon chip (2) and a circuit board (13) carrying the silicon chip (2) is described.
10. Elektronikbaustein mit einem Drucksensor nach Anspruch 1, der auf eine Leiterplatte (13) montiert ist, die in einem von zwei Wandungen (14, 15) umschlossenen Gehäuse angeordnet ist d a d u r c h g e k e n n z e i c h n e t , daß die Abdeckung (7) zwischen einer Wandung (14) und der Leiterplatte (13) dichtend eingespannt ist, und daß an den Abschlüssen der Abdeckung (7) angeordnete Dichtlippen (9) einen Durchbruch (16) in der Wandung (14) umschließen, wobei von dem Durchbruch (16) ein Kanal (17) nach außen führt, der in etwa parallel zur Wandung (14) verläuft. 10. Electronic component with a pressure sensor according to claim 1, which is mounted on a circuit board (13) which is arranged in a housing enclosed by two walls (14, 15) so that the cover (7) is between a wall (14) and the circuit board (13) is tightly clamped, and that sealing lips (9) arranged at the ends of the cover (7) enclose an opening (16) in the wall (14), with a channel (17) leading from the opening (16). leads to the outside, which runs approximately parallel to the wall (14).
PCT/DE1995/000907 1994-07-21 1995-07-11 Protective diaphragm for a silicon pressure sensor WO1996003629A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP8505349A JPH10503021A (en) 1994-07-21 1995-07-11 Protective diaphragm for silicon pressure sensor
KR1019970700391A KR970705015A (en) 1994-07-21 1995-07-11 Protective diaphragm for silicon pressure sensor
EP95924852A EP0771415A1 (en) 1994-07-21 1995-07-11 Protective diaphragm for a silicon pressure sensor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4425921.2 1994-07-21
DE4425921 1994-07-21

Publications (1)

Publication Number Publication Date
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WO (1) WO1996003629A1 (en)

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EP1096243A2 (en) * 1999-10-28 2001-05-02 Motorola, Inc. Physical sensor, in particular semiconductive pressure sensor
US6506110B1 (en) 1997-11-28 2003-01-14 Siemens Aktiengesellschaft Ventilation device, especially for electrical control devices
US6769319B2 (en) 2001-07-09 2004-08-03 Freescale Semiconductor, Inc. Component having a filter
FR2854023A1 (en) * 2003-04-16 2004-10-22 Valeo Systemes Dessuyage Electrical/electronic device e.g. electronic pump head, case for e.g. internal combustion engine, has membrane with cover fixed to external face of closing plate to extend upper end of channel to block channel in water-tight manner
EP1593478A1 (en) * 2004-05-05 2005-11-09 Schreiner Group GmbH & Co. KG Process for covering and venting a functional part and sheet arrangement for performing such process
DE102010022642A1 (en) 2010-06-04 2011-12-08 Rolls-Royce Deutschland Ltd & Co Kg Flow checking device for oil or fuel in aircraft engine by filter arrangement, has measuring conduit that is parallel to differential pressure sensor between two measuring conduit arms, and protective membrane arranged in connecting line
CN101179910B (en) * 2006-11-10 2012-11-14 罗伯特·博世有限公司 Pressure balancing device for housing
DE102012202038A1 (en) 2012-02-10 2013-08-14 Rolls-Royce Deutschland Ltd & Co Kg Measuring device with a pressure sensor
EP2848909A1 (en) * 2013-09-13 2015-03-18 Hella KGaA Hueck & Co. Gas sensor and motor vehicle with a gas sensor
CN105697001A (en) * 2016-03-31 2016-06-22 杭州乾景科技有限公司 Oil-submersible underground temperature measuring and pressure measuring device
CN107063324A (en) * 2017-04-21 2017-08-18 士彩材料科技（苏州）有限公司 A kind of sensor protection mechanism of waterproof and breathable

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JP2015025769A (en) * 2013-07-29 2015-02-05 ビフレステック株式会社 Test body information detection unit, test body information processing apparatus, and method of manufacturing test body information detection unit
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Cited By (18)

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Publication number Priority date Publication date Assignee Title
US6506110B1 (en) 1997-11-28 2003-01-14 Siemens Aktiengesellschaft Ventilation device, especially for electrical control devices
EP1096243A2 (en) * 1999-10-28 2001-05-02 Motorola, Inc. Physical sensor, in particular semiconductive pressure sensor
EP1096243A3 (en) * 1999-10-28 2002-06-12 Motorola, Inc. Physical sensor, in particular semiconductive pressure sensor
US6453749B1 (en) 1999-10-28 2002-09-24 Motorola, Inc. Physical sensor component
US6769319B2 (en) 2001-07-09 2004-08-03 Freescale Semiconductor, Inc. Component having a filter
FR2854023A1 (en) * 2003-04-16 2004-10-22 Valeo Systemes Dessuyage Electrical/electronic device e.g. electronic pump head, case for e.g. internal combustion engine, has membrane with cover fixed to external face of closing plate to extend upper end of channel to block channel in water-tight manner
WO2004093509A2 (en) * 2003-04-16 2004-10-28 Valeo Systemes D'essuyage Housing comprising an air flow conduit preventing all liquid accumulation
WO2004093509A3 (en) * 2003-04-16 2005-04-28 Valeo Systemes Dessuyage Housing comprising an air flow conduit preventing all liquid accumulation
EP1593478A1 (en) * 2004-05-05 2005-11-09 Schreiner Group GmbH & Co. KG Process for covering and venting a functional part and sheet arrangement for performing such process
CN101179910B (en) * 2006-11-10 2012-11-14 罗伯特·博世有限公司 Pressure balancing device for housing
DE102010022642A1 (en) 2010-06-04 2011-12-08 Rolls-Royce Deutschland Ltd & Co Kg Flow checking device for oil or fuel in aircraft engine by filter arrangement, has measuring conduit that is parallel to differential pressure sensor between two measuring conduit arms, and protective membrane arranged in connecting line
DE102012202038A1 (en) 2012-02-10 2013-08-14 Rolls-Royce Deutschland Ltd & Co Kg Measuring device with a pressure sensor
EP2848909A1 (en) * 2013-09-13 2015-03-18 Hella KGaA Hueck & Co. Gas sensor and motor vehicle with a gas sensor
CN104459027A (en) * 2013-09-13 2015-03-25 赫拉胡克公司 Gas sensor and motor vehicle with a gas sensor
US9372102B2 (en) 2013-09-13 2016-06-21 Hella Kgaa Hueck & Co. Gas sensor and motor vehicle with a gas sensor
CN105697001A (en) * 2016-03-31 2016-06-22 杭州乾景科技有限公司 Oil-submersible underground temperature measuring and pressure measuring device
CN105697001B (en) * 2016-03-31 2018-12-21 杭州乾景科技有限公司 Latent oil underground thermometric pressure measuring unit
CN107063324A (en) * 2017-04-21 2017-08-18 士彩材料科技（苏州）有限公司 A kind of sensor protection mechanism of waterproof and breathable

Also Published As

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JPH10503021A (en) 1998-03-17
KR970705015A (en) 1997-09-06
EP0771415A1 (en) 1997-05-07

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