Technological aspects of applying conductive adhesives for inner connections in PCB

In the paper it will be presented the idea of "metallization" of the through holes and the blind holes in PCBs by electrically conductive adhesives. The influence of adhesive rheology and stencil printing parameters for the quality of through hole filling, measured as the resistance of adhesive fill were investigated. The cross sections of hole filling were done to check the mechanism of filling. It was found that for the holes diameter O S and 0.8 mm in 1 mm laminate thick, the average joint resistance is significantly below I Ω and process has 100% efficiency. After establishing the stencil printing parameters for through bole filling, the adhesives were printing into the blind holes diameter 0.15, 0.30 and 0.45 mm. The good blind holes filling for diameters 0.30 and 0.45 mm were achieved. The fill resistance was stable and below 5 Ω. It was found that by changing the way of printing it is possible to decrease the fill resistance of blind holes.