Conductive adhesives for through holes and blind vias metallization

In the paper we propose the idea of “metallization” of the mechanically drilled through holes and the laser drilled blind holes by isotropic conductive adhesives in PCB manufacturing. Such processes can be used instead of electrochemical plating processes and are environmentally friendly. The investigations show that the filled through holes have the average resistance of about 100 mΩ while filled blind vias have average resistance of about 1 Ω in the case of PCBs with pure Cu pads. Better results were obtained if the Au pads metallization was applied onto the Cu layer. In that case the average fill resistance for through holes diameter 0.5 mm and 0.8 mm are about 50 mΩ and for vias 0.3 mm about 150 mΩ. The results are very promising for practical application.