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

Abstract

The paper presents in the frame of an EU Project “Sustainably SMART” the first results on the development of ecofriendly PCB embedding technologies toward advanced electronic modularization and miniaturization. It focuses on the further development of embedding technologies deploying accurate “face-down” assembly techniques, lamination in epoxy prepreg layers and state-of-the-art PCB processes for the breakdown of complex electronic systems in functional modules with discrete functionalities that can be at the end assembled flexibly with non-permanent interconnection techniques on the mainboard. These embedding technologies offer the advantage of the heterogeneous integration of components — with different functionalities, thicknesses and already existing in the market as pre-packaged components with solder terminations (e.g BGA, CSP)- in the inner layer of PCBs as assembled components and then the redistribution of their signals in the outer layers through copper electroplated microvias and drilled through vias. Based on this concept, the digital voice recorder (DVR) of end user Speech has been split in base and functional modules. The new designs of the USB, power, and DSP modules will be presented and the manufacturing processes and results of the digital signal processing (DSP) module will be discussed in detail. This paper demonstrates miniaturized DSP modules, 15mm×15mm×2.8mm comprising 68 components with DSP and quartz crystals to be embedded and flash memory and passives to be assembled as SMT components on top. The creation of such modules with the right adjustment of their termination pads will lead to a reduction of the backbone from 6 to 4 or even 2 layers with a conspicuous positive economic and environmental impact.