Issue link: https://iconnect007.uberflip.com/i/1104607
APRIL 2019 I PCB007 MAGAZINE 77 Additionally, copper-filled microvias have significant advantages over plugging technol- ogy. For instance, the material inside the mi- crovia is copper while other materials have the potential to outgas or introduce different CTE values. Moreover, voids in copper-filled micro- vias are far less common than with poorly con- trolled conventional plugging methods. The development and introduction of copper- filled microvias opened the door to introduce any layer HDI technology (Figure 4), which en- ables copper-filled through-holes by stacking the copper-filled microvias. This kind of fea- ture enables HDI board designers the flexibil- ity to create complex signal paths through the PCB by just using copper filled microvias. Today, almost all critical dimensions of mi- crovias may be filled inclusion-free with cop- per. Table 1 shows the microvia dimensions that can be filled in horizontal and vertical Figure 2: Plugged and capped microvia [2] . Figure 4: Any layer technology stacked and filled with electrolytic plated copper. Figure 3: TQFP footprint with vias and via-in-pads [3] . Table 1: Copper-filled microvias (dimensions that can be filled today).