Abstract: A method for mixing magnetic particles and creating a liquid turbulence with a liquid medium in a reaction chamber is provided, comprising providing an external magnetic field to the reaction chamber causing the magnetic particles to move, such as swirl or oscillate, etc., substantially on a plane crossing the reaction chamber, and simultaneously controlling the magnetic particles to have a relative reciprocating movement at a non-zero angle to the plane. The magnetic field can be provided by rotating or reciprocating a magnet or an electromagnet array around the reaction chamber, or by coordinately activating at least two electromagnets. The relative reciprocating movement of the magnetic particles can be realized by moving the reaction chamber or the magnet array, or by alternately activating another magnetic field. An apparatus applying the method is further provided. The technology can be applied widely and has the potential for realizing true automation.

Abstract: A method or mixing magnetic particles with a liquid medium in a reaction chamber is provided, comprising providing an external magnetic field to the reaction chamber causing the magnetic particles to move, such as swirl or oscillate, etc., substantially on a plane crossing the reaction chamber; and simultaneously controlling the magnetic particles to have a relative reciprocating movement at a non-zero angle to the plane. The magnetic field can be provided by rotating or reciprocating a magnet or electromagnet array around the reaction chamber, or by coordinately activating at least two electromagnets in an electromagnet array. The relative reciprocating movement of the magnetic particles can be realized by moving the reaction chamber or the magnet array, or by alternately activating another magnetic field provided by another electromagnet array. An apparatus applying the method is further provided. The technology can be applied widely and has the potential for realizing true automation.

Abstract: The present invention teaches formulations, apparatus and a method of applying high thixotropic index polymer thick-film resistive pastes for making polymer thick-film resistors with improved tolerances by providing a squeegee with a blade tilted at an angle of 10° to 85° to the surface of the printed circuit board thus causing a fluid rotational motion within the bead of the polymer thick-film resistive paste as the squeegee blade moves relative to the printed circuit board. This rotational motion increases the shear strain rate experienced by the paste within the bead and results in a more effective filling of the resistor-shaped cavity without including air bubbles, experiencing elastic recovery of the paste and, without surface fractures of the paste.

Abstract: The present invention teaches formulations, apparatus and a method of applying high thixotropic index polymer thick-film resistive pastes for making polymer thick-film resistors with improved tolerances by providing a squeegee with a blade tilted at an angle of 10 to 85 to the surface of the printed circuit board thus causing a fluid rotational motion within the bead of the polymer thick-film resistive paste as the squeegee blade moves relative to the printed circuit board. This rotational motion increases the shear strain rate experienced by the paste within the bead and results in a more effective filling of the resistor-shaped cavity without including air bubbles, experiencing elastic recovery of the paste and, without surface fractures of the paste.

Abstract: A method of fabricating multi-layer circuit structure with embedded polymer resistors comprises forming a plurality of electrically conductive paths on a first substrate, forming polymer resistor paste between first and second of the electrically conductive paths on the first substrate, curing the polymer resistor paste by exposure to ultraviolet radiation to thereby solidify the shape of the polymer resistor paste, heating the polymer resistor paste to produce a first resistor, forming a plurality of electrically conductive paths on a second substrate, bonding the first and second substrates with an adhesive, wherein the first resistor is positioned between the first and second substrates.

Abstract: A method of fabricating a polymer resistor in an interconnection via in a printed circuit board includes forming a plurality of first conductive traces on a substrate, forming an interconnection via through one of the first conductive traces in the substrate and terminating at a second conductive trace, filling polymer resistor paste in the interconnection via so as to contact the second conductive trace, thermally treating the polymer resistor paste to produce a polymer resistor, and forming a conductive layer in contact with the resistor and the one first conductive trace.

Abstract: A process is disclosed for forming resistors on a printed circuit substrate. The method includes the step of applying a photoresist layer onto substrate, and forming openings in the photoresist layer to expose the preselected regions for resistors, such that polymer thick resist pastes as well as resistive metallic films can be applied onto the substrate through these openings with precise geometry. The process according to the invention has higher accuracy and greater processing flexibility than the prior art processes where the resistor pastes are directly applied onto the substrate by screen printing.

Abstract: Polymer thick film resistor pastes with dimensionally stability and excellent processibility, such as coating, printing, and extruding, are disclosed. The resistor paste composition in accordance with the present invention comprises a low-k cycloaliphatic epoxy resin vehicle loaded with electrically conductive particles, a cationic photoinitiator, a thermal catalyst, and optionally a reactive diluent.