Screen
printing is the most common method used for the production of printed
electronics. Formulating copper (Cu) inks that yield conductive fine
features with oxidation and mechanical robustness on low-temperature
substrates will open up opportunities to fabricate cost-effective
devices. We have formulated a screen-printable Cu metal-organic decomposition
(MOD) ink comprising Cu formate coordinated to 3-(diethylamino)-1,2-propanediol,
a fractional amount of Cu nanoparticles (CuNPs), and a binder. This
simple formulation enables ∼70–550 μm trace widths
with excellent electrical [∼8–15 mΩ/□/mil
or 20–38 μΩ·cm] and mechanical properties
with submicron-thick traces obtained by intense pulse light (IPL)
sintering on Kapton and poly(ethylene terephthalate) (PET) substrates.
These traces are mechanically robust to flexing and creasing where
less than 10% change in resistance is observed on Kapton and ∼20%
change is observed on PET. Solderable Cu traces were obtained only
with the combination of the Cu MOD precursor, CuNP, and polymer binder.
Both thermally and IPL sintered traces showed shelf stability (<10%
change in resistance) of over a month in ambient conditions and 10–70%
relative humidity, suitable for day-to-day fabrication. To demonstrate
utility, light-emitting diodes (LEDs) were directly soldered to IPL
sintered Cu traces in a reflow oven without the need for a precious
metal interlayer. The LEDs were functional not only during bending
and creasing of the Cu traces but even after 180 min at 140 °C
in ambient air without losing illumination intensity. High definition
television antennas printed on Kapton and PET were found to perform
well in the ultrahigh frequency region. Lastly, single-walled carbon
nanotube-based thin-film transistors on a silicon wafer were fabricated
with a screen-printed Cu source and drain electrodes, which performed
comparably to silver electrodes with mobility values of 12–15
cm2 V−1 s−1 and current
on/off ratios of ∼105 and as effective ammonia sensors
providing parts per billion-level detection.
We present a novel methodology for the design of miniature lumped element components embedded in a low-temperature co-fired ceramic (LTCC) package. The entire process, from initial schematic design, through individual element design, to complete device optimization is discussed. The design and fabrication of novel miniature lumped element LTCC filters is used to validate the proposed methodology. Commercial software tools are used to accurately model and simulate all aspects of the devices to ensure design success. In addition, the filters occupy only 0 03 0 05 0 004 of a conventional low-permittivity LTCC substrate, which is among the smallest sizes reported. An advantage of these filters is that they use a true third-order topology with three multilayer L-C resonators, leading to superior stopband performance. For the first time, measured results are shown for two new bandpass filters targeted for global positioning system applications. Measured results are in good agreement with the simulations and show an insertion loss of 2.8 dB and a return loss of 21.3 dB at the center frequency of 1.64 GHz.Index Terms-Bandpass filters, global positioning system (GPS), low-temperature co-fired ceramic (LTCC), lumped-element filter.
We present two novel ultra-wideband (UWB) antennas embedded in a low-temperature co-fired ceramic (LTCC) package designed to house the UWB transceiver chip. Given their planar topology, circuit integration possibilities, and compact size, a partial ground-plane triangular monopole antenna (PGP-TM) and an antipodal Vivaldi antenna (AVA) are fully characterized. The performance in both the frequency and time domain are presented. The PGP-TM employs parasitic elements for tuning of the antenna's return loss. The PGP-TM antenna's measured 3.5-6.5-GHz bandwidth and omnidirectional pattern with 0-dB gain is suitable for the direct-sequence UWB (DS-UWB) lower subband, while the AVA's measured bandwidth of 3.35 GHz from 6.65 to 10 GHz and 5-dB gain make it suitable for the DS-UWB upper subband. The complete LTCC module containing the PGP-TM measures only 30 mm 25 mm 1.2 mm, while the AVA module measures 50 mm 25 mm 1.2 mm. Both LTCC modules can accommodate transceiver electronics because of a specially designed circuit feature. The effects of path loss can be canceled by combining these antennas in a transmission system. These are believed to be the first demonstrations of system-in-package technology for UWB applications.Index Terms-Antipodal Vivaldi antenna (AVA), low-temperature co-fired ceramic (LTCC), path loss, system-in-package (SIP), ultra-wideband (UWB) antennas.
We present a new fully embedded lowtemperature co-fired ceramic (LTCC) bandpass filter with the highest reported stopband attenuation in its class. The filter occupies only 0.03 λ x 0.05 λ x 0.004 λ of conventional low permittivity LTCC substrate. An advantage of this filter is that it is a true fourth-order design utilizing four multilayer L-C resonators. For the first time, measured results are shown for this novel topology and indicate an insertion loss of 6.7 dB and a return loss of 17.2 dB at the center frequency of 1.64 GHz. The stopband attenuation is greater than 50 dB at frequencies beyond ±300 MHz of the passband, making this filter suitable for GPS environments with harsh spectral interference. This is believed to be the highest performing filter, in terms of out of band attenuation, realized in LTCC.Index Terms-Bandpass filters, global positioning system, low-temperature co-fired ceramic (LTCC), lumped-element filter.
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