Heptanol flow in irregularly shaped surface grooves in Pd-coated Cu is shown to be an example of Poiseuille flow with simple Washburn kinetics of the form z 2 ) C(γ/µ)t, where γ is the liquid surface tension, µ is the viscosity, and C is a function of the groove dimensions and the contact angle θ. A shape independent expression is derived for the geometric factor, C(S,w,θ) ) (S cos(θ)w)/4π, where w is the width of the groove at the surface and S is the arc length, or total length of groove surface in a plane perpendicular to the groove axis. This expression is general for any groove shape and reduces to the form derived previously for V-shaped grooves. Along with scanning electron microscopy, three different techniques, stylus profilometry, laser profilometry, and optical interferometry, were used to characterize the groove geometry, especially to determine S and w. While reasonable agreement is obtained between literature values of γ/µ and values obtained from the experimental kinetics, the main conclusion is that measurement of the groove dimensions is the main limitation to experimental verification of the form of C and to the use of the kinetics of groove flow as an absolute measure of the factor γ/µ. However, we show that if C is calibrated for a specific groove with a known liquid, the kinetics of capillary flow in open surface grooves furnishes a simple, easily applied method for measurement of the surface tension-to-viscosity ratio, γ/µ. LA9712247

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Using Low-Density Fan-Out (LDFO) packaging technology, a radio frequency (RF) microelectromechanical systems (MEMS) tunable capacitor array composed of electrostatically actuated beams on 180nm high-voltage CMOS silicon was heterogeneously integrated with a single-pole four-terminal (SP4T) RF switch on 180nm CMOS silicon-on-insulator (SOI). The primary objective of this study was to determine the manufacturability of this System-in-Package (SiP) design, which is proven at time zero through survival of the MEMS device based on acceptable MEMS performance metrics. In addition, the RF SOI switch provides high-voltage electrostatic discharge (ESD) protection for the MEMS device. Capacitive MEMS structures are particularly sensitive to unpredictable electrostatic charging scenarios, such as handling after package assembly and printed circuit board (PCB) surface mount processing. Consequently, resistance to dielectric breakdown by means of robust ESD protection is a very desirable quality. Integrating the RF switch in close proximity with the MEMS device not only enables the ability to withstand charging scenarios in excess of 1kV (human body model), it mitigates the impact of parasitics on RF performance by minimizing interconnect lengths and complexity.