Motorola Corporation

Zenith Radio Corporation

William R Bratschun

John L Leicht

James A Wrezel

Solder pastes presently harden or congeal over time. This results in wasted solder paste and in production down time. This hardening is a result of the long polymer chains created by the dicarboxylic acid in the activator and the indium (In) or tin (Sn). A solder paste is described in which the metal alloy is coated by an agent that inhibits the reaction with the dicarboxylic acid. One solution involves coating the metal alloy powder with monocarboxylic acids, which truncate the polymer chain. Another manner for truncating the polymer is to coat the metal alloy powder with complexing agents. The metal alloy powder can also be coated by a stable metal such as lead (Pb), gold (Au), silver (Ag), bismuth (Bi), palladium (pd), platinum (Pt), a silver palladium alloy (AgPd) or a silver platinum alloy (AgPt).

Solder paste

An electronic assembly (100) includes multiple solder connections (101) coupling faying surfaces (202, 204) of two substrates (106, 108). A solder connection (201) is fabricated by reflow heating of a first, less compliant solder paste (312, 314) and a compliant preform (210) so as to cause compliant material of the preform (210) to dissolve into the solder paste (312, 314). Upon solidification of the solder paste (312, 314), blended regions (520, 522), having a gradual, changing concentration of compliant material form between resulting fillets (212, 214) and the preform (210). The blended regions (520, 522) transfer temperature induced shear stresses, caused by thermal cycling of the electronic assembly (100), from the fillets (212, 214) into the compliant preform (210).

Alloy solder connect assembly and method of connection

A method of welding two dissimilar metals of substantially different melting temperatures by passing an electric current through an interface created by biasing a projection located on the higher melting point metal into intimate contact with a surface located on the lower melting point material. The electrical current substantially liquifies a portion of only the second metal so that the projection is not substantially deformed by the welding operation.

Welding design for plated, dissimilar metals

A method of forming a connector assembly in association with a hybrid circuit by soldering a plurality of relatively rigid connectors thereto, the resulting assembly being capable of self-supporting the hybrid circuit without the use of ancillary mechanical supporting devices when plugged into a suitably configured printed circuit board or the like. According to the method, a predetermined amount of solder paste is deposited on each of the hybrid circuit substrate terminal pads and one end of each of the rigid connectors is positioned on a respective one of the thusly formed solder paste fillets. Heat is then applied to the substrate reflowing the solder paste fillets and thereby enveloping the terminal pads and their associated connectors for achieving a high strength non-mechanically supported solder connection between each of the connectors and its associated terminal pad. In one embodiment of the invention, two such hybrid circuit-connector assemblies are formed simultaneously.

Hybrid circuit connector assembly

An alumina substrate thick film circuit includes capacitors sealed with two intermediate layers of non-conductive material and two layers of sealing glass. The temperature coefficient of expansion of the sealing glass is less than that of the substrate. The temperature coefficient of expansion of the intermediate layer material is intermediate those of the substrate and the sealing glass, or equal to that of the sealing glass.

Growing community of inventors

La Grange, IL, United States of America

William R Bratschun