Texas Instruments Corporation

Sensata Technologies, Inc.

Stanley J Lukasiewicz

Vishwa N Shukla

Allan J Siuzdak

Robert P Bishop

Lawrence E Cooper

Charles M Anastasia

Gregg W Pestana

Keith W Kawate

Bernard M Kulwicki

Francois A Padovani

Steven Beringhause

Robert O Southworth

Paul L Hainey

Charles J Leedecke

David F Lynch

Peter H Frackelton

Robert E Luminello, Jr

A fluid pressure sensor ( ) has a generally polyhedron configured capacitive transducer ( ) electrically connected to a flexible circuit using interference fit U-shaped edge connectors ( ). The flexible circuit ( ) is received in an electronics chamber formed in a top end of a base member ( ) with the corners of the transducer disposed on the face surface ( ) of the top. A cover ( ) is formed with a circular fluid pressure opening ( ) through which a sealing gasket ( ) extends, the gasket having tabs ( ) received in a seat ( ) formed in the bottom surface of the top wall ( ) of the cover. A transducer receiving seat ( ) is also formed in the bottom surface of the cover for placement of transducer ( ). The cover is formed with opposing legs ( ) which interfit with notches ( ) in the base and a third leg ( ) slidingly received in a slot formed in the base through which conductive tails ( ) of the flexible circuit ( ) extend for electrical engagement with a hexport ( ) slidingly received over the cover and top portion of the base member.

Pressure sensor apparatus

A fluid pressure responsive capacitive transducer (20) having a lowered manufacturing cost is shown in which a sheet (10) of cast or roll compacted tape material having a selected thickness is partitioned into a multitude of rectangular substrates portions (16) and another sheet (12) having another selected thickness is partitioned into a like number and sized diaphragm portions (18) and are processed in sheet form to apply capacitor plates and associated conductive traces as well as a sealing and spacing glass layer. At least one sheet is then separated into groups, generally comprising one, two or four portions, and pairs of groups of substrates and diaphragms are held together and heated to seal the transducers. Groups of more than one portion of the first and second sheets are then separated into individual transducers.

Pressure transducer apparatus and method for making

A capacitive fluid pressure transducer is shown formed of a monolithic ceramic body (10) having a cavity located between a diaphragm portion (12) and a base portion (14). Opposed capacitor plates (22, 24) are disposed on opposed surfaces of the diaphragm portion and the base portion. The capacitor plates (22, 24) are formed of palladium oxide/silver having a ratio selected to create a fluid pressure level in the cavity as a result of oxygen evolution incident to the reduction of palladium oxide during the sintering cycle to offset the tendency of the diaphragm to bow inwardly due to shrinkage mismatch of the metal and ceramic materials.

Method for making a fluid pressure transducer

A monolithic capacitive pressure transducer is shown composed of ceramic material having a closed cavity formed near a surface thereof and having capacitor plates formed on two opposed surfaces defining the cavity. Vias are formed extending from the capacitor plates to permit electrical connection therewith. The transducer is made by separately forming under pressure a diaphragm and a base having a recess in the top surface using ceramic powder coated with an organic binder. A metal layer is deposited on the two pieces and the pieces are then joined together to form a single unit. A spacer may be inserted in the recess to ensure that a predetermined gap is maintained between the two parts during the joining operation. The parts are then debinderized by heating in air to a first temperature level to allow the binder organics, as well as the spacer organics if a spacer is employed, to be vaporized and/or decomposed and removed through the open pores of the diaphragm and base. The unit is then brought up to a sintering temperature in a reducing atmosphere to change it into a monolithic body and to convert the metallized layer into a conductive layer bonded to the ceramic.

Method of making a pressure transducer apparatus

A monolithic capacitive pressure transducer (12) is shown composed of ceramic material having a first closed cavity (12) separated from a surface thereof by a flexible wall member and a second closed cavity (16) defined by rigid wall members. Capacitor plates (32, 36; 40, 44) are formed on two opposed surfaces defining each cavity. Vias (33, 37; 41, 45) are formed extending from the capacitor plates to permit electrical connection therewith. The transducer is made by separately forming under pressure a diaphragm (20) and first and second base portions (22, 30) having recesses (24) in the top and bottom surfaces using ceramic powder coated with an organic binder. A metal layer is deposited on the pieces which are then joined together to form a single unit. A spacer (26) may be inserted in the recesses to ensure that a predetermined gap is maintained in each cavity during the joining operation. The parts are then debinderized by heating to a first temperature level to allow the binder organics, as well as the spacer organics if a spacer is employed, to be vaporized and/or decomposed and removed through the open pores of the diaphragm and base. The unit is then brought up to a sintering temperature to change it into a monolithic body and to convert the metallized layer into a conductive layer bonded to the ceramic.

Pressure transducer apparatus with monolithic body of ceramic material

A monolithic capacitive differential pressure transducer (10, 44,) is shown composed of ceramic material having first and second cavities formed adjacent to opposed face surfaces to form first and second flexible diaphragms (12, 14; 50, 52) and a motion transfer pin (24, 58) attached to and extending between the diaphragms. Capacitor plates are disposed on a surface of at least one flexible diaphragm and a stationary member to form a capacitive gap. Component parts are first pressed from ceramic powder and assembled into a unit using one of several methods including relatively high pressure to press them together or using a combination of low pressure along with raising the temperature of the material to soften the binder in the ceramic material at surfaces of the parts which are to be joined together. Selected gaps, both along the x-y direction and along the z direction may be obtained, particularly in assembling the parts using high pressure using consumable spacer material which is sublimated in a debinderization cycle prior to sintering of the unit to form a monolithic body.

Pressure transducer apparatus

An array of raised lands disposed in columns and rows formed of ceramic material, particularly barium strontium titanate, is formed by making a die of resist material having a negative image pattern of the array on a ceramic substrate and then forming a slurry having a high solid content of the ceramic material, filling the pattern with the slurry and firing the filled die to produce a sintered array of pixels. In a modified embodiment a pressing pad 18 of deformable ceramic tape is formed and pressed into the die after the die has been filled with slurry 16 in order to compact the material and wipe the ceramic material from the sidewalls 12. In another embodiment a ceramic tape of the type used for the pressing pad is pressed into the die and after a short time removed from the die with the pixel array formed in the tape which is then fired to sinter the array. In a modification of this embodiment that portion of the tape extending out of the die beyond the sidewalls 12 can be removed and the die then fired to form a pixel array which is confined essentially to vertical shrinkage upon firing.

Process for forming ceramic pixel array and pixel array formed thereby

Titanate ceramic materials are made by forming a common solution (10) of barium acetate, strontium acetate, isopropyl titanate, lactic acid and water, forming a mist of particles of approximately 50 um or smaller, directing a carrier stream of gas (14) through the mist into a reaction zone in a furnace (20) where the material is pyrolyzed and then collected as a powder in a filter (24) or deposited onto a substrate. The tetra-isopropyl titanate and lactic acid may be replaced by commercially available titanium ammonium lactate. In a first embodiment the carrier gas is an oxidizing gas while in a second embodiment it is an inert gas resulting in powder having greater density.

Method for producing titanate powder and product made thereby

A pressure sensor for providing an electrical signal corresponding to pressure in a cylinder of an automotive engine has a rigid load-spreading element rigidly secured to a first surface of a ceramic piezoelectric body by a rigid bonding material precisely conformed to the first surface to be in substantially uniform load-transferring relation to all parts of the first body surface, has a rigid support member rigidly secured to a parallel, opposite surface of the ceramic piezoelectric body by a rigid bonding material precisely conformed to the opposite surface to be in substantially uniform load-transferring relation to all parts of the opposite body surface to form a piezoelectric unit, and has a peripheral part of the rigid support member precisely mounted with an interference fit in a bore in a metal component of a mounting structure so that the body of piezoelectric material and the load-spreading element extend in cantilever relation at a precisely determined location to be engaged by force applied through a diaphragm in response to an applied pressure to provide an electrical signal precisely corresponding to the pressure.

Cylinder pressure sensor for an internal combustion engine

A presure sensor for providing an electrical signal corresponding to pressure in a cylinder of an automotive engine has a rigid load-spreading element rigidly secured to a first surface of a ceramic piezoelectric body by a rigid bonding material precisely conformed to the first surface to be in substantially uniform load-transferring relation to all parts of the first body surface, has a rigid support member rigidly secured to a parallel, opposite surface of the ceramic piezoelectric body by a rigid bonding material precisely conformed to the opposite surface to be in substantially uniform load-transferring relation to all parts of the opposite body surface to form a piezoelectric unit and has a peripheral part of the rigid support member precisely mounted with an interference fit in a bore in a metal component of a mounting structure so that the body of a piezoelectric material and the load-spreading element extend in a cantilever relation at a precisely determined location to be engaged by force applied through a diaphragm in response to an applied pressure to provide an electrical signal precisely corresponding to the pressure.

Growing community of inventors

North Attleboro, MA, United States of America

Stanley J Lukasiewicz