Motorola Corporation

Beltone Electronics Corporation

Bernard Greenstein

James Mrozack, Jr

A low noise miniature potentiometer utilizes thick film deposits of resistive material which extend adjacent to deposits of conductive material. The conductive region is sliced into a plurality of spaced-apart conductive elements. Electrical paths through resistive elements can be lengthen by laser trimming of the resistive material thereby providing for very precise incremental resistances between pairs of spaced apart conductive elements. If desired, an increased range of resistivity can be achieved by utilizing a second deposited thick film region extending along the conductive region and in contact therewith. Laser trimming can be used to increase conductive path lengths in the second resistive element thereby providing a broader range of resistance values.

Low noise precision resistor

A precision thick film resistor has a deposited thick film conducting layer which is adjacent to and in contact with a deposited thick film resistive layer. A laser scribed line, having a width on the order of 2 mils, separates the conductive region into two parts and then extends into the resistive layer. The value of the resistor is set based on the extent that the line extends into the resistive layer. A plurality of thick film conducting elements can be formed by depositing a continuously extending thick film conducting layer on a substrate. Laser scribed lines can be used to isolate various conducting elements in the deposited film from one another. Elements are separated from one another by 2 mil wide laser scribed lines.

Precision thick film elements

A solder bonding technique for bonding discrete circuit elements to conductors on an alumina substrate. The conductors are composed of palladium and silver, and atop each conductor at a bonding site, a layer of silver is provided. A layer of solder is disposed over the layer of silver. The compliancy of the silver layer absorbs stresses created by thermal cycles and thereby improves the peel strength of the solder bond.

Solder bonding with improved peel strength

A semiconductor die is mounted on a metal substrate via intermediate layers which permit the die to be readily soldered to the combination while yet reducing thermal stresses. A dielectric layer is formed over the substrate, followed by another layer of a selected metal, either molybdenum or tungsten. Atop the metal layer is another layer comprising a mixture of solder and the selected metal. A layer of only solder is formed over the mixture, and the semiconductor die is bonded thereto by means of the layer of solder.

Low stress heat sinking for semiconductors

A pressure sensor assembly includes a pressure transducer having a pressure displaceable diaphragm bonded to a base. Displacement of the diaphragm results in varying of electrical characterisitcs of the transducer in response to sensed pressure. Electrical output connections (wires) of the transducer extend from a central portion of a top surface of the base, which faces the diaphragm, to a central portion of a base bottom surface and peripheral portions of the diaphragm and base top surface are hermetically bonded together. The transducer is mounted on a carrier plate and integral extensions of the electrical output connections pass through holes in the carrier plate. A housing for the sensor assembly has an opening therein to provide access to the diaphragm by ambient atmosphere/fluid surrouding the housing. A first inner seal bonds at least the peripheral portions of the base bottom surface to the carrier plate, and a second outer seal is positioned between the carrier plate top surface and walls of the housing. The housing walls, carrier plate and first and second seals form an effective seal against ambient atmosphere/fluid which contacts the diaphragm and, therefore, seal and protect the electrical output connections of the transducer. The housing walls form an internal cavity which is isolated from the sensed ambient atmosphere/fluid. Within the internal cavity components are connected to the extensions of the clectrical output connections which pass through the carrier plate holes.

Growing community of inventors

Glenview, IL, United States of America

Bernard Greenstein