Sophia Systems Co., Ltd.

Henry L Myers

Joram Diamant

A polymer-based solder paste composition having the strength and corrosion resistance of joints produced by conventional solder technology and the environmental and processing advantages of ICA technology comprises a powdered solder metal with a single component (single package) polymerizable flux composition. In one embodiment the polymerizable flux composition includes 55-70% by weight of an epoxy such as epoxy novolac, the diglycidyl ethers of bisphenol A and F, and mixtures thereof, 0-15% by weight of a dicarboxylic acid, 3-5% by weight of an amine thermal curing agent, and the balance may include a polyalcohol, a chelating agent, a defoamer, a thixotrope and a surfactant. In another embodiment the polymerizable flux composition includes approximately 55-70% by weight of an epoxy such as trifunctional epoxide of p-aminophenol, approximately 20-30% by weight of a liquid organic acid such as a carboxy-acrylate, and approximately 4-10% by weight of an amine thermal curing agent. Organic solvents such as linear hydrocarbons and esters of lactic acid may be added to decrease the viscosity as necessary. Upon heating, the solder metal spontaneously segregates from the flux composition, fuses, and forms a metallurgical joint, while the single-component polymerizable flux composition encapsulates the fused metal in a polymer coating which remains firm but pliable at reflow temperatures.

Polymerizable flux composition for encapsulating the solder in situ

A polymer-based solder paste composition having the strength and corrosion resistance of joints produced by conventional solder technology and the environmental and processing advantages of ICA technology comprises a powdered solder metal with a single component (single package) polymerizable flux composition. The polymerizable flux composition includes 55%-65% by weight of an epoxy such as epoxy novolac, the diglycidyl ethers of bisphenol A and F, and mixtures thereof, 0-15% by weight of a dicarboxylic acid, 9%-11% by weight of a polyalcohol, 3%-5% by weight of an amine thermal curing agent, and the balance including a chelating agent, a defoamer, a thixotrope and a surfactant. Upon heating, the solder metal spontaneously segregates from the flux composition, fuses, and forms a metallurgical joint, while the single-component polymerizable flux composition encapsulates the fused metal in a polymer coating which remains firm but pliable at reflow temperatures.

A dimensionally stable, UV hardenable polymeric composition is provided in which a conductive filler material is combined with a solventless resin formulation comprising a low viscosity epoxide compound, a photo initiator, and a thermal cure initiator. The properties of the polymeric composition may be adjusted through the addition of reactive diluents, poly alcohol flexiblizers, and acrylate based polymers, photo initiators, and thermal cure initiators. Conductive traces produced by extruding the polymeric composition through a syringe are subjected to a preliminary UV hardening step followed by deposition of an insulator layer and additional conductive traces, until all layers of conductive traces have been deposited. The structure is then subjected to heat until the conductive traces are fully cured. The formulation and the process described produce traces with bulk conductivity at least two times higher than any comparable conductive polymer, without using solvents. This process is purely additive, non-polluting and does not produce waste.

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San Jose, CA, United States of America

Henry L Myers