Metal treatment – Compositions – Fluxing
Patent
1990-09-17
1992-03-03
Rosenberg, Peter D.
Metal treatment
Compositions
Fluxing
148 24, 148 25, B23K 3534
Patent
active
050929437
ABSTRACT:
Solder pastes having vehicles including blends of low boiling point alcohols and relatively high boiling point alcohols are described which leave residues which may be cleaned using only water are described. The low boiling point alcohols have a boiling point range of between about 65.degree. and about 150.degree. C. whereas the high boiling point alcohols have a boiling point in rhe range of about 150.degree. to about 270.degree. C. The solder pastes also use water-soluble organic acids as fluxing agents such as compounds of the formula: ##STR1## where R is an electron withdrawing group such as fluorine, chlorine, bromine, iodine, sulfur, hydroxyl, nitrile, and benzyl. Other suitable formic-acid fluxing agents include, but are not limited to, adipic acid, polyacrylic acid, methacrylic acid and polymethacrylic acid. The compounds clean oxides from the printed circuit boards (PCBs) under assembly and then volatilze leaving a residue to be cleaned away. The cleaning step involves rinsing with water. No undesired residue remains indicating that the organic acids of the invention are effective in cleaning boards. Malic acid is a preferred organic acid fluxing agent.
REFERENCES:
patent: 2898255 (1959-08-01), Thompson
patent: 3436278 (1969-04-01), Poliak
patent: 3734791 (1973-05-01), Poliak
patent: 3796610 (1974-03-01), Sarnacki et al.
patent: 4460414 (1984-07-01), Hwang
patent: 4541876 (1985-09-01), Hwang
Absbract to J. Brous, "Effects of Water Soluble Flux Materials on Circuit Board Insulation Resistances", Proceedings of the Technical Program of the National Electronic Packaging and Production Conference, vol. 1, pp. 125-39, 1981.
Davis James L.
Landreth Bobby D.
Mulligan Robert J.
Nounou Fadia
Pennisi Robert W.
Motorola Inc.
Nichols Daniel K.
Rosenberg Peter D.
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