Performance of laser machined and metallized via holes in LTCC tape materials

This paper deals with analyses of laser-machined via interconnections in LTCC (Low Temperature Co-fired Ceramics) substrates with regard to geometrical performance of holes and electrical characteristics of metallized via holes. Tapes and compatible via filler pastes from different suppliers have been tested. In order to realize via interconnections with different diameters the optimal laser parameters have been determined experimentally for each selected tape. The smallest possible holes manufacturable with an optimized reliable laser machining process were determined experimentally for each tested tape material. The results of optimized via hole configurations are shown in the green state. Accordingly, qualification criteria are indicated. Electrical measurements have been carried out in order to determine the electrical resistance of metallized via interconnection depending on via diameter.