SOLDER PASTE UTILIZING AROMATIC CARBOXYLIC ACIDS

摘要

A solder paste that maintains its original viscosity over time and avoids rheology deterioration is disclosed. The invention includes coating solder alloy particles with an aromatic carboxylic acid or a mixture of acids to protect the solder alloy from reacting chemically with the flux and maintain the paste viscosity and deposition capability. In one embodiment, solder powder is treated by soaking the solder particles in an aromatic carboxylic acid solution and heat drying. In an alternative embodiment, the coated particles are dried under vacuum. The coated solder particles are then mixed with flux and formed into a paste. The aromatic carboxylic acid coating, by bonding strongly to the metal powder surface, serves as a non-soluble protective barrier against flux at ambient temperature and a flux-aid at elevated temperature.