Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G13/00—Apparatus specially adapted for manufacturing capacitors; Processes specially adapted for manufacturing capacitors not provided for in groups H01G4/00 - H01G11/00
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L1/00—Measuring force or stress, in general
  • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
  • G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
  • G01L1/148—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors using semiconductive material, e.g. silicon
• • 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
  • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
  • G01L9/0072—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance
  • G01L9/0073—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance using a semiconductive diaphragm
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/0802—Details
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/125—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by capacitive pick-up
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G5/00—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture
  • H01G5/16—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture using variation of distance between electrodes
  • H01G5/18—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture using variation of distance between electrodes due to change in inclination, e.g. by flexing, by spiral wrapping
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P2015/0805—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration
  • G01P2015/0822—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass
  • G01P2015/0825—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass for one single degree of freedom of movement of the mass
  • G01P2015/0828—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass for one single degree of freedom of movement of the mass the mass being of the paddle type being suspended at one of its longitudinal ends

Definitions

• the present invention relates to the technical field of methods or methods for mounting on a support, a mechanical part comprising a flexible element defining, with the support, a variable capacitor.
• Such parts are intended to constitute, preferably but not exclusively, a membrane or a sensor of mechanical quantities, of the capacitive type.
• a capacitive sensor of mechanical quantities such as force, pressure or acceleration, intended to deliver electrical signals representative of the quantities measured and to be applied to electronic processing chains, in order to allow automatic measurements, controls, regulations or controls.
• such a capacitive sensor is in the form of a cantilever beam, made of a monolithic semiconductor substrate and comprises, at least, a flexible element of determined thickness, attached to a anchor foot on the substrate.
• the flexible element determines a movable armature of a variable capacitor, the fixed armature of which consists of a conductive zone formed in the substrate.
• the interarmature space is constituted by the clear interval which separates the flexible element from the substrate.
• the manufacturing technique of these sensors presents a first particular difficulty which is that of determining, with precision.
• the thickness of the flexible element This dimensional characteristic must be determined with precision, so that allow Obtaining a given sensitivity sensor.
• a second production difficulty lies in respecting the difference in level existing between the substrate and the flexible element, insofar as this difference constitutes the interarmature space determining the initial capacity of the variable capacitor thus formed.
• a first method of manufacturing these sensors consists, in accordance with US Pat. No. 4,676,092, of attacking a base substrate to a determined depth, in relation to the initial thickness of the substrate, so as to leave a flexible element of corresponding thickness.
• a drawback of this technique lies in the fact that the flexible element cannot have reduced thicknesses, insofar as the substrate must have a relatively large thickness in order to have sufficient mechanical strength.
• this technique does not make it possible to obtain specific thicknesses for the flexible element, insofar as the base substrates have different initial thicknesses due to manufacturing tolerances.
• a second manufacturing process known from Le document
• a third manufacturing process has been developed, according to patent application EP 89-420 370.2, to overcome the drawbacks mentioned above and allowing the production of a sensor whose sensitive element has a thickness which can be determined, at will and precisely, regardless of the initial thickness of the base substrate.
• This manufacturing process consists in carrying out photogravure operations of sensitive layers deposited on the opposite faces of the substrate, so as, on the one hand, to form a peripheral zone delimiting the outline of the sensor and, on the other hand, to delimit the contour of the anchoring foot.
• the peripheral zone is attacked to form a groove of depth determined with respect to the corresponding face and equal to the thickness of the flexible element.
• the substrate is also attacked along its opposite face to the bottom of the groove, so that the sensor detaches from the substrate to be placed in a non-attack zone, making it possible to obtain a flexible element of determined thickness.
• the invention aims to solve this problem by proposing a method of mounting on a support of a mechanical part, comprising at least one flexible element defining, with the support, at least one variable capacitor making it possible to define, with precision, the interval between the flexible element of the part and the support.
• the invention also aims to offer a method of mounting a mechanical part on a support ensuring positioning of the reinforcements in substantially parallel planes.
• Fig. 1 is a perspective view illustrating an embodiment of a mechanical part suitable for implementing the mounting method according to the invention.
• Fig. 2 is a sectional view taken substantially along Line II-II of FIG. 1.
• Figs. 3A to 3H are sectional views showing an example of the various phases of production of a mechanical part according to the invention.
• Fig. 4 is a partial section view explaining the mounting method according to the invention.
• Fig. 5 is a sectional view showing a mechanical part mounted on a support.
• Fig. 6 is a sectional view showing another embodiment of a mechanical part adapted to be mounted on a support by means of the method according to the invention.
• Fig. 7 is a sectional view showing another embodiment of a mechanical part allowing the mounting method according to the invention to be implemented.
• Figs. 1 and 2 illustrate an exemplary embodiment of a mechanical part 1 adapted to constitute, in this example, an integrated sensor of mechanical quantities and capable of providing a level signal compatible with electronic processing techniques.
• the sensor 1, which can, in particular, constitute an accelerometer, is produced, preferably but not exclusively. into a basic substrate of monocrystalline silicon.
• the sensor 1 is constituted by at least one anchoring foot 2 having a planar connecting face 3 extending in a reference plane P_.
• the sensor 1 also comprises at least one and, in the example illustrated, two elements 4 which are deformable in bending and attached to the anchoring foot 2 while extending in overhang from the latter.
• the flexible elements 4 are connected together, at their free end, by an end portion 5.
• Each flexible element 4 has a face 6 extending in a plane P .. situated behind the reference plane P_ and defining, in relation of the end part 5, an armature 7 of a capacitor whose function and constitution will be detailed in the following description.
• each flexible element 4 is made of a material sufficiently doped to form electrodes or conductive armatures.
• each flexible element 4 has a determined thickness _E of between 10 and 100 microns, while the measurement j ⁇ , separating the planes P_ and P .., is of the order of a few microns.
• the sensor 1 is provided with an additional thickness 8 located substantially at. plumb with the connecting face 3 of the anchoring foot.
• the additional thickness 8 the function of which will appear more clearly in the following description, is intended to present at least one part which is established directly above the connecting face 3 and, in order to be salient with respect to the face 9 flexible elements 4, opposite the face 6.
• the overshoot 8 has a planar face 11 extending in a plane sensitly. parallel to the planes P_, P 1 and establishing itself almost completely in relation to the connecting face 3.
• the sensor 1 described above is preferably produced by the manufacturing process illustrated in FIGS. 3A to 3H.
• a substrate 12 of a type suitable for the part to be produced such as monocrystalline silicon in the example illustrated, a sensitive layer 13 is deposited on the reference face A of the substrate. (fig. 3A).
• the sensitive layer 13 is subjected to a photoengraving operation (FIG. 3B), intended to delimit the contour _ of the connecting face 3 of the anchoring foot 2.
• the face _A is then attacked to a determined depth corresponding to the measurement _e (fig. 3C).
• a sensitive layer 14 is then deposited on the face of the substrate which has just been attacked (FIG. 3D).
• the sensitive layer 14 is then subjected to a photoengraving operation (FIG. 3E) making it possible to form a peripheral zone delimiting the plane contour of the sensor, as defined at the level of the plane P ...
• the peripheral zone _ £ is subjected to an etching attack, so that a groove 15 of determined depth appears corresponding to the thickness _E of the flexible elements 4 (FIG. 3F).
• a photoetching operation of this layer 16 is carried out to delimit, in plan, the side 11 of the extra thickness 8 (fig. 3H).
• the face A is subjected to an etching attack which is continued to the bottom of the groove 15, so as to obtain the cutting of the sensor from the substrate 12.
• the sensor thus cut corresponding to that illustrated in FIGS. 1 and 2, is immediately placed in an etching stop zone, making it possible to obtain flexible elements 4 of determined thickness _E.
• the method of manufacturing the sensor described above can implement a plasma attack or an anisotropic or isotropic attack liquid bath.
• the sensor 1 thus manufactured is intended to be mounted, in accordance with the invention, on a support 18, so that each movable frame 7 of a flexible element 4 is positioned in relation to the distance of a fixed frame 19, to form a capacitor.
• the gap, separating the face of the fixed armature 19 and the face 6, constitutes the dielectric of the capacitors thus formed.
• the support 18 is constituted by an alumina substrate having a thickness of the order of 0.6 to 1 millimeter.
• the constituent of the eutectic deposited is gold, the thickness of the layer of which is on the order of a micron.
• the fixed frame 19 is also produced on the support, preferably by means of the deposition of a layer of gold.
• the fixed armature 19 are connected by conductive paths, not shown, to connections allowing access to the terminals of the fixed and mobile armatures.
• the sensor 1 is intended to be moved, by means of a gripping tool 22 cooperating with the additional thickness 8, so that the connecting face 3 of the anchoring foot 2 comes to cooperate with the fixing zone 21 of the support. . Furthermore, the gripping tool 22 exerts a localized force on the face 11 of the additional thickness 8, so as to ensure a planar contact between the connecting face 3 and the support 18.
• the plane positioning of the anchoring foot 2 on the support 18 makes it possible to guarantee a value given to the interval existing between the frames 1, 19.
• the sensor 1 and the support 18, which can be placed on a heating plate 24, are subjected to a rise in temperature to a point of eutectic eutectic, the first constituent of which is formed by the gold deposited in the zone 21 and the second constituent by the material constituting the sensor.
• the support 18 and / or the sensor 1 is simultaneously subjected to mechanical stresses making it possible to obtain an interdiffusion between the two constituents of the eutectic.
• Such mounting by brazing ensures effective attachment of the part on the support.
• the mounting method according to the invention therefore makes it possible, from a sensor having at least one flexible element 4, of given thickness E, to obtain a determined interval between the fixed armature 19 and the movable armature 7 of a capacitor, since the measurement i of the sensor corresponds exactly to this interarmature interval, due to the method of fixing used which ensures the positioning of the connecting face 3 directly at the surface 18a of the support, to the thickness close to Zone 21 and the frame 19.
• the plane support obtained, between the connecting face 3 and the surface 18_a_ of the support makes it possible to position the frames 1 , 19 in parallel planes. Compliance with the two characteristics set out above ensures a precise determination of the capacity of the capacitor or capacitors thus formed.
• FIG. 6 illustrates a mechanical part 1 forming a membrane consisting of a flexible element 4 attached to two anchoring feet 2 each provided with an additional thickness 8.
• the mechanical parts can be made of a given material, such as silicon or copper, depending on the intended application.
• the material constituting the support 18 " , t chosen so that the coefficient of expansion of this material is substantially of the same order as that of the material constituting the mechanical part 1.
• suppr ⁇ t must also provide insulation between the area 21 for fixing the anchoring foot and the fixed frame 19.
• the support 18 must also allow the deposition of layers of a material intended to form the fixing zone 21 and the fixed frame 19.
• a material which is particularly suitable for assuming all these functions attached to the support 18 is alumina.
• Fig. 4 illustrates, in a simplified manner, an exemplary embodiment of a gripping tool 22 allowing the implementation of the mounting method according to the invention.
• the tool 22 comprises a gripping head 26 in which is formed, on its transverse face 26a, an open recess 28 delimited by a peripheral edge 28a, preferably in relief, ensuring a support and centering function for the additional thickness 3 of sensor 1.
• the recess 28 has, for example, a cross section of polygonal shape to ensure centering of the overshoot 8 having an at least partially complementary contour.
• the head 26 is also provided with at least one suction duct 31 opening into the recess 28 to create a depression, between the bottom of the recess 28 and the face 11 of the extra thickness, so as to ensure the holding the sensor cooperating with the peripheral edge 28a_ of the recess.
• the gripping head 26 is also equipped with a pressing member 32 opening into the recess 28 so as to be able to exert a localized force on the overshoot 8.
• the pressing member 32 is provided with a ter ina part pointed 32a_ and is removably mounted in the head 26, while offering a possibility of adjusting the height of the terminal part 32a projecting inside the recess 28.
• the gripping head 26 is adapted on a conventional machine, not shown, capable of ensuring the movement of the sensor from its storage area to the mounting support 18.
• the gripping head can also be animated with linear reciprocating and / or rotating movements to submit
• the sensor has mechanical stresses when it is in contact with the support.
• the tool 22 can also be driven with alternating linear and / or rotary movements to subject the support to vibrations.
• the mechanical stresses exerted on the support or the sensor to obtain a suitable interdiffusion between the constituents of the eutectic are generated by ultrasound generated by a source not shown.
• Fig. 7 illustrates another embodiment of a gripping tool for implementing the mounting method according to the invention.
• the gripping head 26 is equipped with a stud 34 provided with suction ducts 31 and with a pressing member 32, such as a tip.
• the tenon 34 is intended to cooperate with a mortise 35 formed in the additional thickness 8 of the sensor, along an axis substantially perpendicular to the face 11.
• the tenon 34 has an external bearing and centering edge 34_ £ intended to cooperate with the edge ring road 35_a of La mortaise.
• the mortise 35 is produced by a conventional photoengraving process.
• the invention finds a preferred application to capacitive type mechanical magnitude sensors.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Manufacturing & Machinery (AREA)
• Measuring Fluid Pressure (AREA)
• Pressure Sensors (AREA)
• Fixed Capacitors And Capacitor Manufacturing Machines (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=9389221

Family Applications (1)

Country Status (4)

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Family Cites Families (5)

• 1989
  • 1989-12-28 FR FR8917545A patent/FR2656687B1/fr not_active Expired - Fee Related
• 1990
  • 1990-12-28 EP EP91901817A patent/EP0507826A1/de not_active Withdrawn
  • 1990-12-28 US US07/917,029 patent/US5297720A/en not_active Expired - Fee Related
  • 1990-12-28 WO PCT/FR1990/000962 patent/WO1991010347A2/fr not_active Application Discontinuation

Non-Patent Citations (1)

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