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F. Steinhäußer, A Talai, G. Sandulache, R. Weigel, A Koelpin, W. Hansal, A. Bittner, U. Schmid:
"Pulse plated silver metallization on porosified LTCC substrates for high frequency applications";
Microelectronics Reliability, 60 (2016), 93 - 100.

Advanced high frequency systems such as needed in modern radar applications, require high conductive
metallizations as well as substrates with areas of variable permittivity. This paper presents the combination of
the selective porosification technology of low temperature co-fired ceramics (LTCC) and electro pulse plated
silver microstrip lines. Bymeans of selective platingmethods, linewidths of 20 μmcan bemanufactured featuring
low resistivity values down to 2.33 μΩ cm, without detectable pore penetration. The substrate permittivity is
measured facilitating a combined method of ring resonator detuning and 3D field simulations resulting in a
reduction of 6.5% with a shift from approx. 7.52 to 7.03 at 66 GHz due to the porosification. As often outlined
in literature, the major challenge in using silver as a conductor lies in its high tendency of agglomeration and
microstructural transformation especially in oxygen containing atmosphere even at lowtemperatures. Therefore,
the effect of different temperature loads up to 500 °C on the dc film resistivity ismeasured using the van der Pauw
technique and is compared to scanning electron microscope analyses.

Advanced high frequency systems such as needed in modern radar applications, require high conductive
metallizations as well as substrates with areas of variable permittivity. This paper presents the combination of
the selective porosification technology of low temperature co-fired ceramics (LTCC) and electro pulse plated
silver microstrip lines. Bymeans of selective platingmethods, linewidths of 20 μmcan bemanufactured featuring
low resistivity values down to 2.33 μΩ cm, without detectable pore penetration. The substrate permittivity is
measured facilitating a combined method of ring resonator detuning and 3D field simulations resulting in a
reduction of 6.5% with a shift from approx. 7.52 to 7.03 at 66 GHz due to the porosification. As often outlined
in literature, the major challenge in using silver as a conductor lies in its high tendency of agglomeration and
microstructural transformation especially in oxygen containing atmosphere even at lowtemperatures. Therefore,
the effect of different temperature loads up to 500 °C on the dc film resistivity ismeasured using the van der Pauw
technique and is compared to scanning electron microscope analyses.

LTCC Porosification Galvanic deposition Permittivity reduction High frequency

http://dx.doi.org/10.1016/j.microrel.2016.02.010