Abstract: In a pressure sensing element made of piezoresistors formed into a silicon substrate, thermally-induced stresses on the piezoresistors and thermally-induced voltage offsets can be reduced by thinning the substrate prior to forming the resistors and then forming the resistors into the thinned-out recess. Forming a circular or disk-shaped recess in the substrate and then forming the resistors therein is believed to cause thermally-induced stresses to be evenly distributed and/or cancelled out on all four piezoresistors of a Wheatstone bridge circuit.

Abstract: A piezoresistive pressure sensor that uses a protective gel to protect the piezoresistive device is susceptible to lead wire failure by vibration-induced waves in the protective gel. Such waves can be reduced and the device made more robust by the use of three-dimensional structures in the gel, which are configured to reduce and/or re-direct vibration-induced pressure waves in the gel. The structures are referred to as “breakwaters” in that they protect lead wires and lead wire connections from wave fronts and the damage that wave-induced pressure on the lead wires causes.

Abstract: MEMS pressure sensing elements, the fabrication methods of the sensing elements, and the packaging methods using the new sensing elements are introduced to provide a way for a harsh media absolute pressure sensing and eliminating the negative effects caused by the gel used in the prior art. The invention uses vertical conductive vias to electrically connect the enclosed circuit to the outside, and uses a fusion bond method to attach a cap with the embedded conductive vias over a device die having a circuit for example a piezoresistive Wheatstone bridge to sense pressure. New packaging methods comprise a) a two-pocket housing structure and using a surface mounting method to attach a new sensing element into one pocket by a ball grid array (BGA), and b) a single pocket structure and using conventional die attach and wire bonding. Both methods can be used for harsh media pressure sensing but without the negative effects caused by the gel in prior art.

Abstract: Dual piezoresistive transducers formed into a single silicon die, are anodically bonded to a pedestal. Two separate pressure ports extend through a plastic housing. The port openings inside the housing are surrounded by a groove having a shape and size that accepts the pedestal. A thin, liquid adhesive is deposited into the groove and allowed to level out. The pedestal is placed into the adhesive and embeds itself therein. Adhesive overflow into the ports is avoided by dimensioning the groove and depositing an amount of adhesive that will fill the groove but not overflow when the pedestal is placed therein. Once the adhesive cures, the adhesive bond strength is greater due to the adhesive being in shear relative to the groove side walls and pedestal sidewalls. The grooved structure provides an apparatus and methodology for precise die mounting and media sealing.

Abstract: A MEMS differential pressure sensing element is provided by two separate silicon dies attached to opposite sides of a silicon or glass spacer, the sides of which are recessed and the recesses formed therein at least partially evacuated. The dies are attached to the spacer using silicon-to-silicon bonding provided in part by silicon oxide layers if a silicon spacer is used. The dies can be also attached to the spacer using anodic bonding if a glass spacer is used. Conductive vias extend through the layers and provide electrical connections between Wheatstone bridge circuits formed from piezoresistors in the silicon dies.

Abstract: Any two segments of a wire bonded on two bond pads at different elevations can be distinguished by a stationary node (or zero-displacement) during its second-mode vibration. In order to boost the natural frequency of such a bond wire to avoid a second-mode resonance occurring at the lowest frequency in the in-plane vibration, a wire can be optimized by connecting two equalized (shortest possible) wire segments to replace a wire consisting of a larger segment and a shorter segment. The purpose is to re-distribute a larger vibration movement in the longer segment with a lower stiffness of an arbitrary bond wire to two smaller equalized segments of an optimized wire to reduce an in-plane vibration to significantly improve the wire natural frequency and reliability in a harsh vibration environment such as over 30 kHz.

Abstract: Dual piezoresistive transducers formed into a single silicon die, are anodically bonded to a pedestal. Two separate pressure ports extend through a plastic housing. The port openings inside the housing are surrounded by a groove having a shape and size that accepts the pedestal. A thin, liquid adhesive is deposited into the groove and allowed to level out. The pedestal is placed into the adhesive and embeds itself therein. Adhesive overflow into the ports is avoided by dimensioning the groove and depositing an amount of adhesive that will fill the groove but not overflow when the pedestal is placed therein. Once the adhesive cures, the adhesive bond strength is greater due to the adhesive being in shear relative to the groove side walls and pedestal sidewalls. The grooved structure provides an apparatus and methodology for precise die mounting and media sealing.

Abstract: Pressure non-linearity in a low pressure sensor device formed from a silicon diaphragm with an embedded piezoresistive transducer is reduced by using a shallow boss or thin stiffener on an ultra-thin diaphragm while the pressure sensitivity of the device is increased with corner trenches.

Abstract: A piezoresistive pressure sensor that uses a protective gel to protect the piezoresistive device is susceptible to lead wire failure by vibration-induced waves in the protective gel. Such waves can be reduced and the device made more robust by the use of three-dimensional structures in the gel, which are configured to reduce and/or re-direct vibration-induced pressure waves in the gel. The structures are referred to as “breakwaters” in that they protect lead wires and lead wire connections from wave fronts and the damage that wave-induced pressure on the lead wires causes.

Abstract: Pressure non-linearity in a low pressure sensor device formed from a silicon diaphragm with an embedded piezoresistive transducer is reduced by using a shallow boss or thin stiffener on an ultra-thin diaphragm while the pressure sensitivity of the device is increased with corner trenches.

Abstract: MEMS pressure sensing elements, the fabrication methods of the sensing elements, and the packaging methods using the new sensing elements are introduced to provide a way for a harsh media absolute pressure sensing and eliminating the negative effects caused by the gel used in the prior art. The invention uses vertical conductive vias to electrically connect the enclosed circuit to the outside, and uses a fusion bond method to attach a cap with the embedded conductive vias over a device die having a circuit for example a piezoresistive Wheatstone bridge to sense pressure. New packaging methods comprise a) a two-pocket housing structure and using a surface mounting method to attach a new sensing element into one pocket by a ball grid array (BGA), and b) a single pocket structure and using conventional die attach and wire bonding. Both methods can be used for harsh media pressure sensing but without the negative effects caused by the gel in prior art.

Abstract: An acceleration switch and method therefor includes providing a conductive substrate and an insulating cap. A recessed area is formed in the insulating cap. An insulating layer is disposed on the conductive substrate. A conductive layer is disposed on the insulating layer. The conductive layer is etched to form a cantilever beam and an electrically isolated island. The insulating layer is etched around the cantilever beam to free the cantilever beam to move. Contacts are disposed on the cantilever beam and in the recessed area such that the contacts are able to electrically contact each other upon application of an acceleration to the switch. The cap is bonded to the conductive layer to hermetically seal the cantilever beam.

Abstract: There is a sensor element (24) for an electronic sensor device (20). The sensor element (24) may have a substrate (43), a pair of proof masses (34a, 34b), a set of drive beams (44), and at least one base beam (46). The pair of proof masses (34a, 34b) are suspended above the substrate (43) and attached to the substrate (43) at fixed anchor points (50). The set of drive beams (44) are positioned between the proof masses (34a, 34b) and the anchor points (50). Each drive beam (44) has a first longitudinal body portion (62) that extends in a first direction and a first flexible spring member (64) that extends along a second direction. The base beam (46) interconnects the set of drive beams (44) and has a second longitudinal body portion (72) and a second flexible spring member (74). The second longitudinal body portion (72) extends along the second direction and the second flexible spring member (74) extends along the first direction.