Interconnect Prototype Research Articles

Three-Dimensional Interconnection With Magnetically Coupled Transition for W-Band Integration Applications

In this article, a new class of 3-D interconnection with the magnetically coupled transition is proposed at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> -band. In contrast to planar approaches, it can connect different components or modules in a complex package with wideband and low-loss performance, even if in separate circuit boards. To overcome the radiation loss, the micromachined rectangular microcoaxial line ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{R}\mu $ </tex-math></inline-formula> CL) is chosen to be the 3-D signal line, owing to its low-weight robust structure and low-crosstalk transmission. The substrate integrated waveguide (SIW) is chosen to act as the common signal line around the components and modules. The soldering process will introduce the unpredictable parasitic reactance, which can deteriorate the transmission performance. To construct a nonsoldering field transformation structure from the TEM mode to the TE10 mode, the U-shaped magnetic slot is etched on the SIW through the direction orthogonal to the current field vector, and the tail of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{R}\mu $ </tex-math></inline-formula> CL is directly open. Meanwhile, the transmission characteristics is studied by analyzing the physics-based equivalent-circuit model of this interconnection. The extraction methods of the key parameters, such as turn ratios in the equivalent circuit, are studied for simplifying the synthesis approach. A back-to-back interconnection prototype is designed by the synthesis guideline. The prototypes are fabricated and measured to validate the correctness of this design. The measured results show that the proposed transition achieves a bandwidth from 85 to 100 GHz with the return loss better than 13 dB and the insertion loss around 1.5 dB, which make it promising for high-density interconnection applications at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> -band.

Fast estimation of RL-loaded microelectronic interconnections delay for the signal integrity prediction

This article presents a modelling method of the signal delays induced by microelectronic interconnections regarding RL impedance load. The method proposed is based on the RLC model of the transmission lines (TL) extracted from the equivalent S parameters. Formulation for estimating the interconnection propagation delay is established according to the behaviour of the TL unit step responses. The second order model is validated with a microstrip interconnect prototype with simulations and measurements in frequency and time domains. The developed propagation delay model was validated with SPICE computations. For that, a transient simulation was performed by considering input signals corresponding to high-speed data of some Gbits/s. Then, accurate results were found for interconnections with different lengths in order of millimetre and also by varying the load values. It was shown that the computed 50% propagation delays present of relative errors about 5%. Copyright © 2011 John Wiley & Sons, Ltd.

An Anchor-Board-Based Flexible Optoelectronic Harness for Off-Chip Optical Interconnects

A flexible optical interconnect prototype at board/card-level using a novel anchor-board-based optoelectronic (OE) harness is experimentally demonstrated at 2 Gb/s. The flexible OE harness comprises a thin polyimide film laminated on two narrow anchor boards where edge-emitting lasers (EELs) and p-i-n photodetectors (PDs) are positioned and integrated with polymer waveguides. High-speed electronics are surface-mounted on two separate printed-circuit boards, making the OE harness detachable and field-reparable. A large EEL-PD lateral alignment tolerance of >1.5 mm for a 15-cm interconnect distance is achieved without any microlens. One or multiple channels can be simultaneously aligned and formed during one single ultraviolet exposure. A cost-effective field repair strategy is thus envisioned.

Wide-bandwidth millimeter-wave bond-wire interconnects

A new type of interconnect has been developed that significantly extends the bandwidth of fixed-length bond-wire interconnects between microwave circuits. This interconnect maximizes bond-wire length, as well as landing pad size while simultaneously extending the cutoff frequency of the interconnect. The bond-wire interconnect is treated as a five-stage low-pass filter where basic filter theory is used to develop an interconnect prototype. Microstrip interconnects are designed using electromagnetic simulators, which match a specific low-pass filter response on a 5-mil thick (127 /spl mu/m) glass substrates. The measurements indicate a return loss greater than 12 dB and an insertion loss from 0.0 to 0.3 dB from DC to 80 GHz using two 17-mil-long (432 /spl mu/m) 1-mil-diameter (25 /spl mu/m) ball bonds with a tolerance of /spl plusmn/2 mil (50 /spl mu/m). For comparison, an uncompensated interconnect with two 17-mil-long (432 /spl mu/m) bond wires has 1-dB insertion loss and 10-dB return loss at 40 GHz and continues to degrade at higher frequencies.

Corrections to "description and evaluation of the fast-net smart pixel-based optical interconnection prototype"

Corrections to "description and evaluation of the fast-net smart pixel-based optical interconnection prototype"

Description and evaluation of the FAST-Net smart pixel-based optical interconnection prototype

The design, packaging approach, and experimental evaluation of the free-space accelerator for switching terabit networks (FAST-Net) smart-pixel-based optical interconnection prototype are described. FAST-Net is a high-throughput data-switching concept that uses a reflective optical system to globally interconnect a multichip array of smart pixel devices. The three-dimensional optical system links each chip directly to every other with a dedicated bidirectional parallel data path. in the experiments, several prototype smart-pixel devices were packaged on a common multichip module (MCM) with interchip registration accuracies of 5-10 /spl mu/m. The smart-pixel arrays (SPAs) consist of clusters of oxide-confined vertical-cavity surface-emitting lasers and photodetectors that are solder bump-bonded to Si integrated circuits. The optoelectronic elements are arranged within each cluster on a checkerboard pattern with 125-/spl mu/m pitch. The experimental global optical interconnection module consists of a mirror and lens array that are precisely aligned to achieve the required interchip parallel connections between up to 16 SPAs. Five prototype SPAs were placed on the MCM to allow the evaluation of a variety of interchip links. Measurements verified the global link pattern across several devices on the MCM with high optical resolution and registration. No crosstalk between adjacent channels was observed after alignment. The I/O density and efficiency results suggest that a multi-terabit switch module that incorporates global optical interconnection to overcome conventional interconnection bottlenecks is feasible.

Redistribution and bumping of a high I/O device for flip chip assembly

Redistribution and bumping of a high I/O device has been successfully achieved at Motorola's Interconnect Prototype Lab using a combination of photosensitive benzocyclobutene (BCB), electroless nickel underbump metallurgy, and photoresist defined solder printing technique. To take full advantage of flip chip packaging technology, redistribution is necessary to rewire bondpads to an area array. BCB was chosen as the interlayer dielectric between the redistributed metal traces and device circuitry. Advantages of BCB include high level of planarization, low moisture uptake, rapid thermal curing, high thermal stability, high solvent resistance, and a low dielectric constant. We successfully optimized many steps in the process flow to redistribute the bondpads. The BCB residue in vias was cleaned with a plasma descum comprised of an Ar/SF/sub 6/ mixture. BCB to BCB adhesion was improved by optimizing the curing time. The shear strength of the bumps was increased 80% by sputter-roughening of the BCB/Al interface. Sematech ATC04-2 functional wafers with 1004 bumps/die and a minimum pitch of 8 mils were successfully redistributed to a 10 mil and 16 mil mixed array pitch and solder bumped using a photodefined squeegee bump technology.

Design and implementation of a prototype optical deflection network

We describe the design and implementation of a packet-switched fiber optic interconnect prototype with a ShuffleNet topology, intended for use in shared-memory multiprocessors. Coupled with existing latency-hiding mechanisms, it can reduce latency to remote memory locations. Nodes use deflection routing to resolve contention. Each node contains a processor, memory, photonic switch, and packet routing processor. Payload remains in optical form from source to final destination. Each host processor is a commercial workstation with FIFO interfaces between its bus and the photonic switch. A global clock is distributed optically to each node to minimize skew. Component costs and network performance figures are presented for various node configurations including bit-per-wavelength and fiber-parallel packet formats. Our efforts to implement and test a practical interconnect including real host computers distinguishes our work from previous theoretical and experimental work. We summarize obstacles we encountered and discuss future work.