Using an electrodynamic-shaker-based test setup, experiments were performed on gold-plated contacts under a variety of fretting conditions, including different vibration frequencies, vibration amplitudes, and different environment temperatures. The variations in contact resistance with fretting cycles are recorded explicitly. The fretted surface is examined using a scanning electron microscope, energy-dispersive X-ray spectroscopy, and a con-focal laser scanning microscope to assess the surface morphology, extent of oxidation, and elemental distribution across the fretted zone. It was found that fretting damage is a complex phenomenon for electrical contact applications. Different fretting regimes, including the robust electrical contact performance, the oxidation-dominated failure, and the transient unstable conductivity failure are determined. Finally, the degradation mechanisms of gold-plated contacts are proposed.

IEEE transactions on components, packaging, and manufacturing technology
ISSN：2156-3950 volume：7 Issue：5 page：751-761
Jeffers, Nicholas
;
Stafford, Jason

This paper investigates the aerodynamic performance of a piezoelectrically actuated cantilever blade operating in the first mode of vibration. Bulk air-moving capability and local velocity field features have been experimentally measured for different operational conditions and blade confinement states. A testing facility has been developed to determine the pressure-flow rate characteristics of a vibrating blade and simultaneously conduct particle image velocimetry. Under high system resistance, similar to that found in densely packed electronics, flow reversal occurs at the blade outlet region analogous to stall. This is accompanied by increased local unsteadiness in the airflow being emitted. Local turbulence intensity increases by 50% between maximum flow rate and maximum efficiency operating points. The introduction of confinement around a vibrating blade reduces bulk air-moving capability significantly, with pressure rise and volumetric flow rate measured as low as 20% of what can be achieved for an unconfined blade. However, there is an accompanying change in spatial velocity distribution, which focuses the flow normal to the outlet. This has potentially beneficial uses for targeted electronics cooling applications. The findings identify the relationship between local and bulk airflow characteristics that ultimately provides information about the sensitivity of this type of air-moving device in practical installations.

This paper presents a slow-wave rat-race coupler using substrate integrated suspended line (SISL) technology. Double-sided interconnected strip line (DSISL) is utilized to further reduce the loss of the suspended line circuit. Using the DSISL concept, a slow-wave structure based on modified meander line configuration is proposed. Formed by simple circuit topology with only three parameters of one unit cell, the characteristic impedance and slow-wave factor of the proposed slow-wave DSISL can be controlled separately. Utilizing the proposed slow-wave DSISL, a rat-race coupler at 1.5 GHz has been designed and fabricated by standard printed circuit board process. A 90.5% size reduction is achieved, and the fractional bandwidth is 26.5%. Benefiting from SISL technology, the proposed slow-wave rat-race coupler is self-packaged and has advantages of low cost and light weight.

This paper presents the fabrication and characterization of radio frequency (RF) and microwave passive structures on an air substrate using additive manufacturing (3-D printing). The air substrate is realized by 3-D printing RF structures in two separate pieces and snapped together face to face using a LEGO-like process. Spacers printed on the periphery provide the desired air substrate thickness. Metal patterning on nonplanar printed plastic structures is carried out using a damascene-like process. Various RF structures such as low dispersion transmission line, T-line resonator, high-gain patch antenna, slot antenna, and cavity resonator are demonstrated using this process. Good performance is achieved; for example, measured 50-<inline-formula> <tex-math notation="LaTeX">\Omega </tex-math></inline-formula> transmission line shows low loss of 0.17 dB/cm at 4 GHz, and a patch antenna (center frequency of 4.5 GHz) shows gain and bandwidth of 7.6 dB and 0.2 GHz, respectively. Details of both measured and simulation results are presented.

Face-to-face (F2F)-bonded 3-D ICs provide higher vertical interconnection densities and cost-effective solutions compared to face-to-back-bonded 3-D ICs. With a bumpless direct-copper-bonding process, the die-to-die distance is significantly reduced to enable a finer F2F via pitch. Unfortunately, this increases interdie parasitic components that require careful extraction. Heterogeneous 3-D ICs are built using dies from different design houses and foundries, potentially using different technology nodes. They again require accurate parasitic extraction across multiple dies and thus call for new computer-aided design methodologies with intellectual property protection. We, for the first time, provide a comprehensive study of three full-chip parasitic extraction methods for homogeneous and heterogeneous F2F 3-D ICs. The traditional die-by-die extraction ignores any interdie coupling and underestimates the total coupling capacitance by 35%. The holistic extraction that takes all dies into account provides the most accurate results at the cost of high layout-versus-schematic (LVS) complexity. The in-context extraction, taking only the interface layers from the neighbor dies, offers tradeoffs between accuracy and complexity. Our study shows that with only two interface layers, in-context extraction offers highly accurate and efficient extraction results with 0.9% error for the total ground capacitance and 0.8% for the total coupling capacitance.

In this paper, a novel embedded dual-element rectangular dielectric resonator antenna (RDRA) combining Sierpinski and Minkowski fractals is proposed to reduce the size and for wideband applications. To enhance the impedance bandwidth, a DR 1 with dielectric material Rogers RT6010 <inline-formula> <tex-math notation="LaTeX">\varepsilon _{r1}= 10.2 </tex-math></inline-formula> is embedded concentrically inside the DR 2 . DR 2 is a rectangular ring with dielectric material FR-4 <inline-formula> <tex-math notation="LaTeX">\varepsilon _{r2}= 4.3 </tex-math></inline-formula> The proposed antenna offers a wide impedance bandwidth of around 3.52 GHz (66%) for <inline-formula> <tex-math notation="LaTeX">S_{11} < -10 dB </tex-math></inline-formula> at a resonant frequency of 3.85 GHz. Experiments have been conducted up to the second iteration of fractal with various indentation factors. Two modes have also been investigated that show presence of both <inline-formula> <tex-math notation="LaTeX">{T\!E}_{11\delta }^{Z}(0 < \delta </tex-math></inline-formula> ≤ 1) <inline-formula> <tex-math notation="LaTeX">{T\!E}_{11\delta }^{Z}(0 < \delta </tex-math></inline-formula> ≤ 1) like modes. The peak gain of proposed antenna is 6.74 dBi at 6.25 GHz. The measured gain is above 5.13 dBi in the frequency range from 3.5 to 7.02 GHz (impedance bandwidth) of operation.

Conventional model-order reduction techniques used in circuit simulation guarantee the passivity and, consequently, the stability of the reduced circuit provided that the original circuit is passive. This excludes a large class of circuits that are stable but not necessarily passive. In this paper, an algorithm is described that guarantees the stability of the reduced circuit by construction. Numerical examples are presented that validate the efficiency and accuracy of the proposed method.

This paper presents a detailed investigation of the differential bandpass filters with high performance using the popular TE<inline-formula> <tex-math notation="LaTeX">_{\mathrm {01\delta }} </tex-math></inline-formula>-mode ring-shaped dielectric resonator (DR). According to the field distribution of the TE<inline-formula> <tex-math notation="LaTeX">_{\mathrm {01\delta }} </tex-math></inline-formula> mode, the design principle for differentially exciting it is constructed, i.e., a pair of feeding probes should be face-to-face. Under this feeding scheme, it can be found that the resonant modes of the DR cavity can be divided into two kinds of responses, i.e., differential-mode and common-mode responses. Furthermore, the differential feeding scheme is flexible, and then two modified differentially fed structures by changing the positions of differential port pair are introduced to improve the filter selectivity by incorporating an additional transmission zero or to enable the filter to meet the requirement of integration with other differential devices. To validate the proposed idea, several design examples of the differential DR filters are presented, and their simulated and measured results are given.

Based on the recognition that near-end crosstalk propagating to the far end is the primary source of crosstalk noise in short unterminated channels, an approach to improve the signal integrity on such channels significantly is described and demonstrated. The basic physics of crosstalk reduction by matrix matching is described and illustrated numerically. Then, large potential gains for three on-package interconnect application examples are shown. A nominal strip-line configuration based on standard package design rules and including realistic modeling assumptions yields 50.4% reduced channel power at equal performance. The same design can be converted into microstrip without degrading the eye height and channel power. For a dense multichip package with design of experiment simulation, the worst-case eye width is improved by 114%.

In this paper, coaxial through-silicon via (C-TSV) is modeled and studied with the consideration of electrically floating inner silicon substrate. Nonlinear capacitances of the central via and the outer shielding shell are accurately captured by solving cylindrical Poisson equation. By employing symbolically defined device block, the nonlinear capacitances of the C-TSV with electrically floating inner silicon are combined into the equivalent circuit model, and their impacts on the electrical characteristics are examined.