Conductive adhesive for plated Sn or Sn/Pb electrode

New isotropic conductive adhesive (ICA) for plated Sn or Sn/Pb electrode was developed. The new ICA and our existing ICA were evaluated for SMT as lead containing solder replacement, using on-chip resistors with plated Sn/Pb (90/10) and fired Ag/Pd terminations, from contact resistance and adhesion strength points of view. The new ICA gave more stable contact resistance and adhesion strength through reliability testing, even in the case of using 0Ω chip resistor with plated Sn/Pb termination. Formation of boundaries or Sn grains on the surface and diffusion of Ni into Sn/Pb layer in the cross section, after chip resistors with plated Sn/Pb termination exposed to several reliability conditions, were observed by SEM and EDX. Though degree of these changes of plated Sn/Pb termination depends on each exposure condition, it can be estimated that the new ICA gets less influence by the changes of plated Sn/Pb termination and that it has some effect which prevents changing by plated Sn/Pb termination before it occurs