An electrical interconnect includes a copper pillar and solder cap. The copper pillar and solder cap are formed onto a contact pad or an under bump metallurgy (UBM). In some applications, the contact pad or UBM is part of an electronic component, such as a semiconductor chip. In other cases, the contact pad is part of laminated substrate, such as a printed circuit board (PCB), or a ceramic substrate. The copper pillar and the solder cap are printed using an ink printer, such as an aerosol ink jet printer. A post heat treatment solidifies the interconnection between the contact pad or UBM, the copper pillar and the solder cap.