Fine line printing technologies for microwave and millimeter wave applications

Current microwave and mm-wave applications require fine lines (<100 micron). For example, Lange couplers and coupled line filters in microwave integrated circuits call for conductor lines with a width less than 100 micron. Conventional screen-printing technology can normally be used to achieve 100 micron lines and spaces. Several techniques have emerged, such as photo imaging, photo etching, and conventional screen printing using a mu-screen and a low,vibration screen printer, which achieve line widths of less than 100 micron. In this communication, several fine line technologies are reviewed The focus of this paper is the development of silver photoimageable paste for post-fired A6 LTCC. 30-micron fine lines have been. accomplished using the photoimaging technique. Adhesion, solderability, and solder leach resistance have been characterized for surface applications. Insertion loss measurements for photoimageable silver conductors with A 6 LTCC are also performed from 1 to 20 GHz using the microstrip ring resonator technique. The superior surface smoothness and line definition of the photoimageable silver conductor leads to lower losses despite of the thinner conductor thickness.