On the application of 3D LTCC and flexible structures based on galvanized layers

This paper describes design, construction and some recent tests of three dimensional stacked structures. These structures have great potential to realize compact structures combining multiple different applications in one package. Interconnections used in these stacked structures pay important role in packaging. They not only provide electrical connection, but they also act as mechanical attachment between substrates and are supposed to be reliable as much as possible. Approach mentioned in this paper might lead to increase of 3D interconnection reliability. Goal of this work is development and implementation of reliable 3D stacked structures, where for example LTCC, Al₂O₃ and also flexible substrates can be connected together in one package by interconnections that are based on vacuum evaporated and galvanically reinforced conductive layers of several types - fixed planar and also elastic ones, both in connection with variable types of solder balls.