The influence of packaging materials on RF performance

At frequencies beyond 1 GHz, every component of the IC package contributes to the RF performance, whether required or not. In this work, we study the effects of packaging materials namely, the substrate and the globtop/underfill material on RF performance. We have measured interconnects on two area-array CSPs, the ball grid array and the polymer stud grid array using IMEC’s MCM-D technology. The measurements on the package interconnect show that the losses in the package substrate material account for about 50% of the total losses at 1.8 GHz and this drops to less than 20% at 5.2 GHz. The losses due to impedance mismatch dominate the losses especially below 10 GHz and considerable improvement in performance cannot be obtained by using an improved/expensive substrate. The other study is about the influence of globtop/underfill materials on wirebonds (through 3D EM simulations) as well as on standard 50 Ω MCM-D transmission lines (through experiments). While a higher value of dielectric constant of the globtop/underfill material is better on wirebonds, the influence of loss tangent is felt only above values of 0.1. The influence of seven different globtop/undefill materials on 50 Ω transmission lines has been used to extract their dielectric constant and loss tangent values at 30 GHz. These results are very valuable since one can hardly find the properties of globtop/underfill materials beyond 1 GHz.     

Determination of the complex permittivity of packaging materials at millimeter-wave frequencies

The focus of this paper is the determination of the complex permittivity of chip packaging materials at millimeter-wave frequencies. After a broad overview of existing measurement techniques, three methods will be presented that have been established for the dielectric property determination of substrate, as well as mold materials (encapsulants, under-fill, etc.) in the millimeter-wave frequency range. First, the open resonator used here will be briefly described. It allows accurate determination of the dielectric constant and loss of thin sheet substrate materials from below 20 GHz to above 100 GHz. Second, a filled waveguide method is explained in detail. The setup used here can determine the complex dielectric properties of mold materials from 70 to 100 GHz. Third, the method based on covered transmission lines will be described in detail. The used lines allow measurements from below 40 GHz to approximately 90 GHz. Verification of all three methods will be provided by inter-comparison and comparison to values from the literature. Additionally, results for several typical substrate and mold materials that are available for millimeter-wave packaging will be shown and discussed.     

Circularly polarised aperture antenna fed by CPW and built in MCM-Dtechnology

A new design for a circularly polarised aperture type antenna fed by a coplanar waveguide, is introduced. The antenna has been built in MCM-D technology which offers an easy way to reduce the leakage to the slotline mode of the CPW. The proposed antenna has been studied both theoretically and experimentally. The results show that the antenna has both a high impedance and high circular polarisation bandwidths. It is designed to operate around 25.5 GHz. Return loss, axial ratio, and radiation patterns are presented and briefly discussed     

Antenna arrays in MCM-D technology fed by coplanar CPW networks

In this paper, the design, fabrication, and characterization of planar antenna arrays in the MCM-D technology are presented. The arrays are fed by coplanar feeding networks built using coplanar-waveguide lines. 2×2 and 4×4 arrays of slot dipoles designed to work in K-band, around 25 GHz, are also presented. The analysis was carried out both theoretically and experimentally. The results include the return loss, radiation patterns, and antenna gain. The proposed arrays are compatible with the driving electronics technology, enjoying high-impedance bandwidth, low cross polarization, high gain, and high radiation efficiency     

X-band brick wall antenna fed by CPW

A brick wall antenna fed by a coplanar waveguide is introduced. This antenna can be considered as an eleven element array of reduced size. Analysis is carried out both theoretically and experimentally. The proposed antenna is designed to work in the X-band ~9.5 GHz. The return loss, radiation pattern, and antenna gain of the proposed antenna are presented and briefly discussed. The antenna has several advantages, such as ease of fabrication, good control of input impedance, small cross polarisation level, and high directivity     

Technologies for highly miniaturized autonomous sensor networks

Recent results of the autonomous sensor research program HUMAN++ will be summarized in this paper. The research program aims to achieve highly miniaturized and (nearly) autonomous sensor systems that assist our health and comfort. Although the application examples are dedicated to human monitoring/assistance, the necessary technology development for this program is generic and can serve many wireless sensor applications. This multi-disciplinary program combines research on wireless ultra-low-power communications, research on 2D/3D integration and packaging platforms, energy scavenging techniques, as well as low-power and ultra-low-power sensor circuit design. An example sensor system is the wearable wireless EEG system.     

RF probe influence study in millimeter‐wave antenna pattern measurements

A Radio Frequency (RF) probe has been fully modeled, and radiation pattern and realized gain of this probe at mm‐wave frequencies have been extracted. Simulation results prove that the probe radiates with a pattern like a dipole showing a realized gain of around ?8 dBi at 60 GHz, which is a huge leakage from a probe. The radiation pattern and the realized gain of the probe at 60 GHz have also been measured, confirming the simulation results. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Wafer-level package interconnect options

As integrated circuit technology enters the nanometer era, global interconnects are becoming a bottleneck for overall chip performance. In this paper, we show that wafer-level package interconnects are an effective alternative to conventional on-chip global wires. These interconnects behave as LC transmission lines and can be exploited for their near speed of light transmission and low attenuation characteristics. We compare performance measures such as bandwidth, bandwidth density, latency, and power consumption of the package-level transmission lines with conventional on-chip global interconnects for different International Technology Roadmap for Semiconductors (ITRS) technology nodes. Based on these results, we show that package-level interconnects are well suited for power demanding low-latency applications. We also analyze different interconnect options such as memory buses, long inter tile interconnects, clock, and power distribution.     

Retaliation as a response to procedural unfairness: A self-regulatory approach.

When does procedural unfairness result in retaliation, and why do recipients of unfair treatment sometimes pursue and other times inhibit retaliation? Five studies addressed these questions. The authors proposed and found that regulatory focus moderates retaliation against an unfairness-enacting authority: Promotion-focus participants were more likely to retaliate than prevention-focus participants. Promotion focus was associated with, and also heightened the accessibility of, the individual self. In turn, individual-self accessibility influenced retaliation. In fact, prevention-focus participants were as retaliatory as promotion-focus participants under conditions of high individual-self accessibility. Implications for the procedural fairness and regulatory focus literatures are discussed, and suggestions for future research are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)