For hand-held communication products, like the DECT telephone system, flip-chip on board offers minimization of both the package size and the occupied area on the boards. As a result of the reduction in interconnection lengths, the self-inductance is reduced. For high volume production, the compatibility of the flip-chip mounting technique with standard surface mount technology (SMT) reflow is essential. During reflow, the eutectic PbSn bump wets along the copper track, so the stand-off between integrated circuits (IC's) and the board is accurately defined by the layout of the board and the dimensions of the bump. The eutectic PbSn flip-chip processing is evaluated by impedance and cross-talk measurements, and in several reliability tests. For the electrical measurements, a zero-IF front-end IC is used. Wide-band measurements of the input impedance showed that the residual parasitics associated with the eutectic PbSn bumps are negligible compared with the parameters of the internal IC components. To accommodate the residual stresses from differences in coefficient of thermal expansion (CTE), the gap between the IC and the substrate is underfilled. This underfill material marginally affects the electrical behavior of the IC at frequencies up to a few GHz. As expected, a slight increase in the residual capacitance is observed. The effect of the underfill is studied by both temperature cycle and shock tests; cumulative failure distributions have been plotted. Results show that the adhesion properties and flow characteristics of the underfill material are the dominating factors for the number of cycles to failure. By selecting the proper underfill and curing conditions, the eutectic PbSn flip-chip construction can meet the test requirements for consumer communication products

Coherent wideband frequency-domain measurements of the complex frequency response of millimeter wave indoor radio channels are discussed. In addition, results of measurements performed in a 2 GHz band centered around 58 GHz will be presented. It is shown that a 40 dB dynamic range and a 400 ns aliasing-free range are sufficient for a correct estimation of the rms delay spread from the measurement data.< >

For the DECT telephone system, a zero-IF front-end Integrated Circuit (UAA2078) has been designed in Philips' high speed QUBIC BiCMOS process. This IC contains all RF circuits required to directly down-convert the RF signal to the IF frequency around zero. At these high frequencies (1.8 GHz), it is advantageous to use flip-chip as mounting technique. Wide-band measurements of the input impedance showed that the residual parasitics associated with the eutectic solder bumps are negligible compared with the parameters of the internal IC components. To accomodate the residual stresses from differences in CTE, the gap between the IC and the substrate is underfilled. This underfill material does not affect chip behaviour too much at frequencies up to a few GHz. To study its mechanical behaviour, cumulative failure distributions have been investigated. The effect of the underfilling is studied by temperature shock-testing. From testing different types of underfill, it appears that the adhesion properties and flow characteristics of the underfill material are the dominating factors for the number of cycles to failure.

A method is presented for designing and dimensioning biconical horn antennas in such way that the level of received power does not depend strongly on the separation distance between a centralized base station and a remote radio terminal within an indoor pico-cell. Results of cell-coverage measurements at 58 GHz are presented using these antennas within eight different indoor environments. The measurement results show that, using biconical horn antennas, an overall uniform coverage can be achieved for both line-of-sight and obstructed line-of-sight topologies.

Coherent wide-band frequency-domain measurements of the complex frequency response of mm-wave indoor radio channels are discussed. In addition results of measurements performed in a 2 GHz band centered around 58 GHz in three different rooms at the Eindhoven University of Technology presented. With respect to the considered multipath radio channels it is shown that a 40 dB dynamic range and a 400 ns aliasing-free range are sufficient for a correct estimation of the RMS delay spread from the measurement data.

Wideband measurements of indoor radio channels operating in a 2 GHz frequency band centred around 58 GHz were performed using a frequency step sounding technique. The results are presented of cell coverage and RMS delay spreas under both line-of-sight (LOS) and obstructed (OBS) situations.

A method is presented for dimensioning biconical horn antennas which give a near uniform coverage within a picocell. This method is applied to the synthesis of a pair of millimetre-wave biconical horn antennas for operation in indoor picocells. Results of cell coverage measurements at 42 GHz are given.