Manufacturing Reliability of LTCC Millimeter-Wave Passive Components

The manufacturing reliability of low-temperature co-fired ceramic circuits up to millimeter-wave frequencies and the associated tolerances are studied. The printing accuracy and software tools are initially verified. In the main part of this study, representative circuit elements are analyzed, i.e., a planar bandpass filter, buried filter, and vertical low-pass network, which take advantage of fine line printing and high-permittivity inclusions. The passive structures are investigated for deviations in the magnitude and phase of their scattering parameters, also analyzing temperature effects. A dispersion characteristic is introduced to the simulations in order to achieve the best match with measurements. All samples show very little manufacturing variations up to 67 GHz and a high reproducibility from run to run.