| abstract |
A lead-free, cream solder composition that is printable includes a SnZn alloy which is lead-free and which is a powder; a solder flux including an epoxy resin; microcapsules that are organic carboxylic acid particles encapsulated with a resin selected from a group consisting of epoxy, polyimide, polycarbonate, polyamide, polyester, polyurea, polyolefin, and polysulfone resins; and a solvent which is a glycol. The presence of the organic carboxylic acid encapsulated with a resin as microcapsules suppresses reactivity of zinc in the SnZn alloy with the organic carboxylic acid Alternately, the solder flux may include the epoxy resin; an organic carboxylic acid; and the solvent; and microcapsules that are particles of a SnZn alloy encapsulated with the described resin. The presence of the SnZn alloy encapsulated with a resin as microcapsules suppresses reactivity of zinc in the SnZn alloy with the organic carboxylic acid so that viscosity and solderability are stabilized. |