An investigation of lead-free thick-film resistors on LTCC substrates - preliminary results

Marko Hrovat , Konrad Kiełbasiński , K. Makarovic , Darko Belavic , Małgorzata Jakubowska


The lead-free thick-film resistors with different ratios of conductive and glass phases were investigated. Four resistor materials with nominal sheet resistivities from 50 ohm/sq. to 50 kohm/sq. were prepared with different combinations of two lead-free glasses with reflow temperatures at 940 \#x00B0;C and 1240 \#x00B0;C, respectively, and two RuO2 powders (fine grained and coarse grained RuO2). Thick-film resistors were printed and fired on alumina and LTCC substrates (Du Pont 951) with the aim to study the influence of interactions between resistor layers and rather glassy LTCC substrates on electrical and microstructural characteristics. The resistors were investigated by X-ray powder diffraction and by SEM/EDXS analyses. Sheet resistivities, TCRs, gauge factors and noise indices were measured. X.ray spectra indicated that the RuO2 do not react during firing with either of two evaluated glasses. The gauge factors were below or around 3, which indicates stable resistance characteristics. The resistivity vs. temperature dependences were remarkably linear with R-squared equal to or better than 0.99. For most resistors sheet resistivities were comparable to the nominal resistivities and noise indices were around or below 0.2 uV/V. However, resistors prepared from the coarse grained RuO2 and the glass with higher reflow temperature the resistivities were an order of magnitude too high and noise indices were between 7 and 10 uV/V.
Author Marko Hrovat
Marko Hrovat,,
, Konrad Kiełbasiński IMiO
Konrad Kiełbasiński,,
- The Institute of Microelectronics and Optoelectronics
, K. Makarovic
K. Makarovic,,
, Darko Belavic
Darko Belavic,,
, Małgorzata Jakubowska IMiO
Małgorzata Jakubowska,,
- The Institute of Microelectronics and Optoelectronics
Book Microelectronics and Packaging Conference (EMPC), 2011 18th European, 2011
Keywords in Englishaluminium compounds, ceramic packaging, gauge factor, glassy LTCC substrate, lead-free glass phase, lead-free thick-film resistor, nominal sheet resistivity, powders, reflow temperature, resistor material, RuO2-Al2O3, ruthenium compounds, scanning electron microscopy, SEM-EDXS analyses, sheet resistivity, TCRs, temperature 1240 degC, temperature 940 degC, thick film resistors, X-ray chemical analysis, X-ray diffraction, X-ray powder diffraction, X-ray spectra
Languageen angielski
Score (nominal)10
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