Package-Level EMI Shielding Technology with Silver Paste for Various Applications

A variety of shaped Ag particles was tested to obtain optimized electrical resistivity and mechanical reliability. We also studied the effect of the spray machine's parameters such as pressure, speed, and droplet size on uniformity of sprayed conductive film. The resulting Ag paste containing flake shaped Ag particles showed about 1×10-7m electrical conductivity. The aspect ratio of top to side coating thickness of the resulting conductive films on EMC mold was 1:0.5~1:0.7, which could be controllable. We found that the best electrical conductivity and mechanical reliability was achieved when only flake shaped Ag were used. Finally, shield effectiveness of resulting EMI shielding film made of Ag and matrix is as high as 60dB, 65dB, 70dB at 5um, 10um, 20um-thick film, respectively by ASTM method.