Patent ID: 7780801

Claim:
A process comprising soldering together at least two surfaces, each of which comprises a metal area to which solder can adhere, and in any order: (a) applying solder to at least one of said metal areas; (b) aligning said metal areas so that they are superimposed over one another; (c) heating at least one of said areas to a temperature that comprises at least the melting temperature of said solder; followed by joining said superimposed areas to one another; wherein said soldering is conducted with a flux composition operatively associated with said solder, where said flux composition consists essentially of a combination of: (a) a fluxing agent; and (b) a solvent; wherein said fluxing agent: ( 1 ) comprises a keto acid; or ( 2 ) comprises an ester acid; or ( 3 ) comprises a mixture of said keto acid with said ester acid; and wherein said solvent consists essentially of a tacky solvent and a non-tacky solvent ( 1 ) wherein said tacky solvent is selected from, ethoxylated glycerol, propoxylated glycerol, or mixtures thereof; ( 2 ) said non-tacky solvent is selected from methanol, ethanol, 2-propanol, 1-methoxy-2-propanol, 2-methoxyethanol, 2-ethoxyethanol, 3-ethoxy 1-propanol, 2-butoxyethanol, ethylene glycol butyl ether, propylene glycol propyl ether, di(propylene glycol) propyl ether, di(propylene glycol) methyl ether, ethyl acetate, acetone, methyl ethyl ketone or mixtures thereof; and wherein said keto acid or ester acid or the mixtures thereof are present in an amount comprising from about 6 weight % to about 15 weight %, said tacky solvent in an amount comprising from about 50 weight % to about 80 weight %, and said non-tacky solvent in an amount comprising from about 10 weight % to about 30 weight %, all based on the weight of said flux composition.