Delco Electronics Corporation

Gm Global Technolgoy Operations, Inc.

John M Hart, Jr

John Michael Matly

Mark Billings Kearney

Dennis Michael Koglin

Joseph M Ratell

Ronald E Brown

Donald E Lake

Michael J Luettgen

A media-compatible, high-pressure transducer cell (12), a rugged sensor assembly (10) incorporating the cell (12), and a method for its production. The pressure cell (12) generally includes a metal body having a diaphragm (26), at least one dielectric layer (28, 38) on the diaphragm (26), and at least one thick-film piezoresistive element (34) on the dielectric layer (28, 38) for sensing deflection of the diaphragm (26). For purposes of compatibility with a wide variety of media, the metal body is preferably formed of steel, most preferably a stainless steel alloy such as an AISI Type 300 or 400 Series. The diaphragm (26) can be formed by etching or machining the metal body. The dielectric layers (28, 38) are preferably formed by thick-film processing as done for the piezoresistive element (34), employing materials that will adhere to the metal diaphragm (26), withstand the strains induced as the diaphragm (26) deflects, and faithfully transmit such strains to the thick-film piezoresistor (34).

Method of making a thick film pressure sensor

A carrier frame has cells with inwardly extending thin flexible tabs. Pressure sensor housings are molded into the frame cells such that only the tips of the tabs penetrate the housing wall and after processing the housings are readily pushed out of the frame. A lead frame is insert molded at the same time. During molding the cells of the frame are open ended and after molding a reinforcing tie bar is attached across the open side of the frame to close the cells. A flange is bent up on the opposite side to lend rigidity to the frame. Preformed code flags are provided in the frame and selectively bent out for coding.

Method of manufacturing a pressure sensor assembly

Apparatus useful in the manufacture of a pressure sensor assembly

A pressure sensor includes a three part package including a housing member defining two spaced-apart chambers, a bottom member providing the bottom wall of one of the chambers, and a top cover member hermetically sealing the two chambers from one another and including a port for admission of gases into one of the chambers. A pressure sensing element is disposed in the chamber having the port and mounted on the bottom member, and a signal processing element is mounted in the other chamber. Electrical connections between the two elements are by means of leads which extend into each chamber and pass through a wall separating the chambers. A low temperature differential between the two elements is provided by extending one of the leads from the other one chamber to a position directly underlying and in intimate contact with the bottom surface of the processing element in the other chamber. Additionally, the bottom member is of a high thermal conductivity material and extends along the bottom of the housing member to beneath the other chamber.

Pressure sensor and method of fabrication thereof

A pressure sensor element comprising a silicon chip having a diaphragm formed therein with piezoresistive strain responsive resistors is mounted in a housing of molded polyester material having a much different temperature coefficient of expansion than the chip. The chip is protected from thermally induced and other stresses by a mounting arrangement comprising a glass base secured to the housing by a soft adhesive which largely prevents stress being transmitted from the housing to the base, wherein the base has a short pedestal on which a glass die is mounted which, in turn, supports the silicon chip. The short pedestal adds localized rigidity to the base so that any stresses in the base are taken up outside the region of the pedestal. One face of the glass die is bonded to the base by a relatively soft epoxy to further inhibit stress transmission and the silicon chip is securedly bonded to the opposite face of the die. Contacts on the silicon chip are wire bonded to conductors which are insert molded in the housing.

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Kokomo, IN, United States of America

John M Hart, Jr