Realization of μ-Vias in LTCC Tape

Today LTCC (Low Temperature Co-fired Ceramics) Technology is established as a key technology for ceramic based interconnects on modules and components. Known for their excellent thermal and high frequency electrical performance, LTCC Technology is gaining new applications e.g. in the automotive and telecommunications market. Over the last years, LTCC materials and production processes have been further developed to meet the needs of these applications. As a result, the layouts of LTCC-modules are characterized by increasing circuit complexity and packaging density. Accordingly, the numbers of layers and vias are increasing, while the dimensions of the circuitry (lines and spaces) are decreasing. On the other side, conventional screen printing is limited to approximately 100 mum of line width (in volume production). This is why photoimageable thick film technology is used in applications requiring high packaging density. Another consequence of shrinking circuit dimensions is the need to reduce the size of via holes, which are usually fabricated by punching or laser drilling. This paper reports results regarding the formation of vias in LTCC tapes. Different methods, i.e. mechanical punching and laser drilling, as well as different lasers (CO2, Nd-YAG and UV) are compared..