Tin and tin - burble liquid null of lead alloy

摘要

PURPOSE:To obtain the soln. capable of releasing a tin or tin-lead alloy layer in a short time without eluting the base copper by incorporating an org. sulfonic acid, in aromatic nitro-substituted compd., thiourea, benzotriazole and catechol into the soln. CONSTITUTION:The aq. soln. which contains an aliphatic or aromatic org. sulfonic acid, an aromatic nitro-substituted compd., thiourea or its derivative, benzotriazole or its derivative and catechol is used for selectively releasing a tin or tin-lead alloy layer. In this case, the base copper is hardly eluted, and the deposition by substitution with the eluted tin or lead is not caused. The soln. appropriately contains about 1g/l of an org. sulfonic acid, about 0.5g/l of a saturated aromatic nitro compd., about 0.5 to 10g/l of a saturated thiourea, abut 0.1 to 5g/l benzotriazole and about 0.1-10g/l of catechol. The soln. having such a composition is used for a dipping or spraying method at about 30 to 45 deg.C, and the tin or tin-lead alloy layer is released in a short time without damaging the base copper.