Laser processing of materials for MCM-C applications

Application of lasers for MCM-C (ceramic multichip modules) technology offers an opportunity to miniaturize passive elements as well as whole substrates. At present, the laser processed thick-film conductive lines can be as small as 20 μm [1]. Processing of unfired LTCC tapes allows achieving hot-plate beams with widths of 250 μm [2]. To realize such fine structures by laser cutting, some understanding of the nature of interaction of the laser beam with the material is necessary. Application of different laser types for microelectronic packaging was discussed earlier, e.g. in [3–8]. In most cases however, Nd:YAG lasers were mainly applied for patterning PCBs, polymers, or silicon wafers, whereas for fired ceramics CO
2
-lasers were used. This paper discusses some phenomena that occur during processing of materials used in MCM-C applications: thick-film layers, fired and unfired ceramics with frequency-tripled Nd:YAG laser.