Semi-aqueous solvent cleaning of paste processing residue from substrates

The present invention relates generally to a new apparatus and method of semi-aqueous solvent cleaning of paste processing residue from substrates. More particularly, the invention encompasses an apparatus and a method that utilizes a semi-aqueous solvent cleaning method for cleaning of paste residue from screening objects comprising the use of at least one propylene-glycol alky-ether solvent. A process of cleaning of objects that relate to semiconductor fabrication processes, such as, for example, conductive paste screening in the production of multilayer ceramic substrates and composite solder paste by stencil printing in electronic circuit assembly. Specifically, the process removes a metal/polymer composite paste from screening masks and associated paste making and processing equipment used in printing conductive metal pattern onto ceramic green sheet in the fabrication of semiconductor packaging substrates. The process also cleans solder paste residue from stencil printing equipment used in electronic module assembly surface mount technology for SMT discretes, solder column attachment, and BGA (Ball Grid Array) attachment on ceramic chip carrier or for screening solder paste onto printed circuit board. More particularly, paste residue is cleaned from metal, ceramic, and plastic substrates by a non-alkaline semi-aqueous cleaning method employing high boiling propylene glycol alkyl ether or mixtures of propylene glycol alkyl ether and propylene glycol solvents.