In the soldering reaction at 200 °C between eutectic SnPb and plated Pd/Ni on Cu leadframes, two thicknesses of Pd of 760 and 2500 Å were used. Even very thin Pd can lead to continuous spreading of the solder on the leadframe; no stable wetting angle can be observed. Anisotropic spreading and spike formation were found due to the mechanical effect of rolling of the leadframe, and they are more pronounced in the thinner Pd samples. In the interfacial reaction, we have observed the formation of a ternary Pd–Ni–Sn compound andNi3Sn4.While spalling of the ternary compound occurs, no spalling of theNi3Sn4was found. The latter forms a rather uniform layer consisting of small scallop-type grains. We found that the growth rate ofNi3Sn4is much slower, by a factor of about 10, than that ofCu6Sn5in the reaction between Cu and eutectic SnPb. ©1997 American Institute of Physics.