Studies were made on cleaning solvent systems for printed wiring board
s on which pricision parts are mounted by soldering them with flux con
sisting of rosin and a polar compound. We anticipated that a mixture o
f diethylene glycol monobutyl ether (DGB) and octamethylcyclotetrasilo
xane (D4) is a promising solvent system having solubility parameter si
milar to those for good solvents of rosin and a high dielectric consta
nt for dissolving the polar compound. As the subsequent cleaning proce
ss, D4 and perfluorooctane (PFO) were examined as rinsing and vapor-dr
ying solvents, respectively. As a result, this cleaning system was fou
nd to be superior to those using water, hydrocarbon or CFC113/ethanol
mixture. A comment was also made on ionic residues on the boards based
on quantitative analysis.