Embedding technologies for heterogeneous integration of components in PCBs-an innovative modularisation approach with environmental impact

The proposed work is performed in the frame of the EU project ""sustainablySMART"" which aims to change the life cycle of mobile information and communication devices by developing new product design approaches for smartphones and tablet computers on the product and printed circuit board level, and by new re-/de-manufacturing processes with improved resource efficiency. In this context, the undertaken research activity on ""Eco-innovative approaches for advanced printed circuit boards"" aims to demonstrate that embedding technologies are environmentally and economically beneficial since they save much surface space on main boards by embedding components in PCB layers. The main outcome is the manufacturing of robust modules as sub-systems with specific functionalities. Based on this approach, the main board architecture of a voice recorder has been modified in order to be split in power, USB and DSP modules. This paper will describe the whole PCB embedding processing for the production of the digital signal processing (DSP) module. Initially, a 6-core layer with through vias and microvias is manufactured and then on its bottom side all the components are assembled which are going to be embedded. These components are the DSP BGA chip, voltage detector, bus buffer, etc. The components after embedding are routed to surface pads of the module. The rest of the components are assembled as SMT components on the surface of the DSP embedded module and these are the Flash memory as BGA package and 2-pad clock crystals. The DSP module together with the other two embedded modules will be assembled on the main board of the voice recorder. The right adjustment of all pads of the embedded modules will lead to a reduction of the 6-layer of the main board to 4 or even 2 layers with an apparent environmental and economical benefit. The embedding has resulted in a miniaturised DSP module of 1.5cmx1.5cmx2.8mm whose reliability and electrical performance will be also demonstrated