Pl. Cavallotti et al., REACTIVITY OF NO-CLEAN PASTES AND FLUXES FOR THE SURFACE-MOUNT TECHNOLOGY PROCESS .1. CORROSION BEHAVIOR OF CU, SN, AND PB, Journal of electronic materials, 24(4), 1995, pp. 365-370
No-clean fluxes allow simplifications in the surface mount technology
process, but introduce reliability problems for electronic assemblies
during their service life. An electrochemical method is devised to stu
dy the anodic reactivity of Sn, Pb, eutectic Sn-Pb solder alloy and Cu
in aqueous solutions containing no-clean paste residues obtained duri
ng a reflow process. The potential corrosion risk of residues from two
different pastes is evaluated, and the corrosion behavior of the diff
erent metals assessed. Cu corrodes faster than Sn, Pb, and the solder
alloy in presence of the residues, but corrosion starts at higher over
voltages. Pb corrodes at low overvoltage; Sn is prone to oxidation and
passivation. The solder alloy has an intermediate behavior between th
ose of the pure metals.