Abstract: A pressure transducer of the type employing a pressure-responsive diaphragm (11) with silicon piezoresistive strain gauges epitaxially deposited thereon is provided with integral digital thermal compensation of span shift and zero shift. The strain gauges are connected in a bridge circuit (30), and a differential voltage across the bridge circuit is amplified by an instrumentation amplifier (46). A temperature sensitive resistor (36) is deposited on the pressure-responsive diaphragm. This resistor is connected in a bridge circuit (35) the output of which is connected to an analog-to-digital (A/D) converter (54) which generates a digital number corresponding to the measured temperature of the piezoresistive strain gauges. This digital number is used to address pre-programmed correction data stored in a programmable read only memory (PROM) (53). The numerical correction data from the PROM is converted by a digital-to-analog (D/A) converter (55) to an analog correction signal.

Abstract: A pressure transducing device in the form of a beam includes a monolithic chip of silicon or similar material which is mechanically supported at and near its two opposed ends and unsupported in a flexible region between the two ends. The flexible, unsupported region is one of maximized sensitivity to stresses produced by deflection or flexing of the beam due to, e.g., a differential pressure applied across it. An integral, pressure-responsive diaphragm is formed in the supported area of the chip near one of its mechanically-supported ends. This area of the chip is relatively insensitive to stresses produced by beam flexing or deflection; rather, it responds to stresses produced by a pressure (e.g., a static pressure) applied directly to its surface. A first set of strain gauges is provided in the flexible chip region, and a second set on the surface of the integral diaphragm.

Abstract: A method of etching a silicon diffused resistance pressure transducer assembly (13) of a transducer (10) mounted on a glass base (14) providing a thin flexible area on the transducer in the region of the diffused resistors (15) and a thick rigid area in the region where the transducer is mounted to the glass base (14). To accomplish this, the transducer (10) is first bonded to the glass base (14) which is tubular, thus providing a circular area on the backside (16) of the transducer (10) open to ambient. This open area is then filled with an isotropic etchant which etches silicon material but which has little effect on glass material. Thus, the region of the diffused resistors (15) is etched out to provide a thin flexible area while leaving a thick area where the transducer (10) is mounted to the glass base (14).

Abstract: A pressure sensitive Silicon chip is indirectly bonded to a Stainless Steel housing of an electronic pressure transmitter through an intermediate holder assembly. This indirect bonding prevents thermal cracking of the Silicon chip due to the difference in thermal expansion of the Stainless Steel housing and the Silicon chip. The holder assembly includes a Borosilicate glass tube having the Silicon chip bonded thereto which tube is soldered to a Nickel-Iron alloy holder by a eutectic alloy solder. In assembly, the Nickel-Iron holder is first brazed to the stainless Steel housing at a first temperature greater than the maximum non-destructive temperature of either the chip or the glass tube and the glass tube is then soldered to the Nickel-Iron holder at a lower temperature which will not destroy the chip or the tube holder.