Contribution to realization of 3D structures

This paper describes design, construction and some recent test results of lead-free soldered three-dimensional structures based on combination of stacked thick-film Al2O3 or LTCC and FR-4 substrates. These various substrate configurations are realized in two ways, at first by lead-free solder bumps made by solder paste stencil printing, and at second by bumps using combination of paste and solder balls. This three dimensional technology offers great potential to very compact embedded structures which may include as hybrid integrated circuits (HIC) well as non-conventional applications (sensors, attenuators etc).