Use of the “Via-In-Pad” Method to Ensure the High-Density Layout of the Conductive Pattern when Designing Multilayer Switching Structures

Abstract

The application features of the Via-in-Pad method when implementing a high-density conductive pattern of multilayer switching structures in electronics is considered herein. The composition method for vias and contact pads for the tracing ability improvement is proposed, and the assessment methodology for the effective area utilization for BGA components is presented. The experimental study of the pressure sensor housing was carried out, which showed that the application of this method made it possible to reduce the number of vias by 40% and place more contact pads per unit area, which frees up the gaps for BGA tracing, reduces the pattern density and microwave signal paths. The obtained results confirmed the possibility of reduction of the usable space by 25%, which makes it possible to arrange more pads per unit area, to free up the gaps for BGA tracing, to reduce the time for drilling the workpieces, to reduce the number of used drills, and also provides the best heat removal from the components. The disadvantage is the large internal resistance of the transitions created by the Via-in-Pad method, in contrast to the standard ones, which can negatively affect the flow of critical signals. By comparing the resistances from the metallization layer of the via in the MPCB with a flexible flat cable and in the MPCB designed using the Via-in-Pad method, it was found that the Via-in-Pad method made it possible to increase the layout efficiency of multilayer printed circuit boards.