Embedding of active and passive components into multilayer printed circuit boards

The common trend towards smaller and more powerful products causes great efforts in the whole electronic industry. In a first step space savings have been realized by using miniaturized components for assembly. In the area of active components this strategy leads to the development and the application of chip scale packages (CSPs) and flip chips. On the part of passive components a size reduction down to housings like 0201 (0.6 x 0.3mm) and currently even 01005 (0.4 x 0.2mm) has been done. It does not seem to be promising to follow up that direction because of technical and economical reasons. An attractive solution in this field could be the integration of active and passive components into the printed circuit board (PWB). In addition to the most obvious advantage of space savings on the surface of the PWB this technology leads to lower assembly costs, better reliability because of the reduced number of solder joints and a better signal integrity. In this paper the authors present a technical overview of the various ways to produce printed circuit boards with embedded active and passive components. Various processes (screen printing, etching, inkjetting) and materials for resistors and capacitors are described as well as reachable tolerances and the reliability of these components. In the area of active components the paper deals with the aspects of choosing the proper raw material to embed thinned dies as stress-free as possible into PWBs as well as the adequate interconnection technology and also the requirements regarding the surface of the die. In addition to that the needed assembly technology for the placement of these ultra thin dies on big production formats is mentioned.